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Sample records for coulomb gauge qcd

  1. Numerical approach to Coulomb gauge QCD

    SciTech Connect

    Matevosyan, Hrayr H.; Szczepaniak, Adam P.; Bowman, Patrick O.

    2008-07-01

    We calculate the ghost two-point function in Coulomb gauge QCD with a simple model vacuum gluon wave function using Monte Carlo integration. This approach extends the previous analytic studies of the ghost propagator with this ansatz, where a ladder-rainbow expansion was unavoidable for calculating the path integral over gluon field configurations. The new approach allows us to study the possible critical behavior of the coupling constant, as well as the Coulomb potential derived from the ghost dressing function. We demonstrate that IR enhancement of the ghost correlator or Coulomb form factor fails to quantitatively reproduce confinement using Gaussian vacuum wave functional.

  2. Feynman rules for Coulomb gauge QCD

    SciTech Connect

    Andrasi, A.; Taylor, J.C.

    2012-10-15

    The Coulomb gauge in nonabelian gauge theories is attractive in principle, but beset with technical difficulties in perturbation theory. In addition to ordinary Feynman integrals, there are, at 2-loop order, Christ-Lee (CL) terms, derived either by correctly ordering the operators in the Hamiltonian, or by resolving ambiguous Feynman integrals. Renormalization theory depends on the sub-graph structure of ordinary Feynman graphs. The CL terms do not have a sub-graph structure. We show how to carry out renormalization in the presence of CL terms, by re-expressing these as 'pseudo-Feynman' integrals. We also explain how energy divergences cancel. - Highlights: Black-Right-Pointing-Pointer In Coulomb gauge QCD, we re-express Christ-Lee terms in the Hamiltonian as pseudo-Feynman integrals. Black-Right-Pointing-Pointer This gives a subgraph structure, and allows the ordinary renormalization process. Black-Right-Pointing-Pointer It also leads to cancellation of energy-divergences.

  3. Convergence of Feynman integrals in Coulomb gauge QCD

    SciTech Connect

    Andraši, A.; Taylor, J.C.

    2014-12-15

    At 2-loop order, Feynman integrals in the Coulomb gauge are divergent over the internal energy variables. Nevertheless, it is known how to calculate the effective action, provided that the external gluon fields are all transverse. We show that, for the two-gluon Greens function as an example, the method can be extended to include longitudinal external fields. The longitudinal Greens functions appear in the BRST identities. As an intermediate step, we use a flow gauge, which interpolates between the Feynman and Coulomb gauges.

  4. Finiteness of the Coulomb gauge QCD perturbative effective action

    SciTech Connect

    Andraši, A.; Taylor, J.C.

    2015-05-15

    At 2-loop order in the Coulomb gauge, individual Feynman graphs contributing to the effective action have energy divergences. It is proved that these cancel in suitable combinations of graphs. This has previously been shown only for transverse external fields. The calculation results in a generalization of the Christ–Lee term which was inserted into the Hamiltonian.

  5. Instantaneous interquark potential in generalized Landau gauge in SU(3) lattice QCD: A linkage between the Landau and the Coulomb gauges

    SciTech Connect

    Iritani, Takumi; Suganuma, Hideo

    2011-03-01

    We investigate in detail 'instantaneous interquark potentials', interesting gauge-dependent quantities defined from the spatial correlators of the temporal link-variable U{sub 4}, in generalized Landau gauge using SU(3) quenched lattice QCD. The instantaneous QQ potential has no linear part in the Landau gauge, and it is expressed by the Coulomb plus linear potential in the Coulomb gauge, where the slope is 2-3 times larger than the physical string tension. Using the generalized Landau gauge, we find that the instantaneous potential can be continuously described between the Landau and the Coulomb gauges, and its linear part rapidly grows in the neighborhood of the Coulomb gauge. We also investigate the instantaneous 3Q potential in the generalized Landau gauge, and obtain similar results to the QQ case. T-length terminated Polyakov-line correlators and their corresponding ''finite-time potentials'' are also investigated in generalized Landau gauge.

  6. Renormalization in the Coulomb gauge and order parameter for confinement in QCD

    NASA Astrophysics Data System (ADS)

    Zwanziger, Daniel

    1998-05-01

    Renormalization of the Coulomb gauge is studied in the phase space formalism, where one integrates over both the vector potential A, and its canonical momentum Π as well as the usual Faddeev-Popov auxiliary fields. A proof of renormalizability is not attempted. Instead, algebraic identities are derived from BRST invariance which renormalization must satisfy if the Coulomb gauge is renormalizable. In particular, a Ward identity is derived which holds at a fixed time t, and which is an analog of Gauss's law in the BRST formalism, and which we call the Gauss-BRST identity. The familiar Zinn-Justin equation results when this identity is integrated over all t. It is shown that in the Coulomb gauge, g2D0.0 is a renormalization-group invariant, as is its instantaneous part V( R), which we call the color-Coulomb potential. (Here D0.0 is the time-time component of the gluon propagator.) The contribution of V( R) to the Wilson loop exponentiates. It is proposed that the string tension defined by KCoul = lim R→∞ CV( R)/ R may serve as an order parameter for confinement, where C = (2 N) -1( N2 - 1) for SU( N) gauge theory. A remarkable consequence of the above-mentioned Ward identity is that the Fourier transform V( k) of V( R) is of the product form V( k) = [ k2D C,C ∗ ( k)] 2L( k) , where D C,C ∗ ( k) is the ghost propagator, and L( k) is a correlation function of longitudinal gluons. This exact equation combines with a previous analysis of the Gribov problem according to which k2D C,C ∗ ( k) diverges at k = 0 , to provide a scenario for confinement.

  7. Coulomb gauge approach for charmonium meson and hybrid radiative transitions

    SciTech Connect

    Gou, Peng; Yepez-Martínez, Tochtli; Szczepaniak, Adam P.

    2015-01-22

    We consider the lowest order interaction of the Foldy-Wouthuysen QED and QCD Hamiltonian in the Coulomb gauge approach, to describe radiative transitions between conventional and hybrids charmonium mesons. The results are compared to potential quark models and lattices calculations.

  8. Coulomb gauge ghost propagator and the Coulomb form factor

    NASA Astrophysics Data System (ADS)

    Quandt, M.; Burgio, G.; Chimchinda, S.; Reinhardt, H.

    The ghost propagator and the Coulomb potential are evaluated in Coulomb gauge on the lattice, using an improved gauge fixing scheme which includes the residual symmetry. This setting has been shown to be essential in order to explain the scaling violations in the instantaneous gluon propagator. We find that both the ghost propagator and the Coulomb potential are insensitive to the Gribov problem or the details of the residual gauge fixing, even if the Coulomb potential is evaluated from the A0 -propagator instead of the Coulomb kernel. In particular, no signs of scaling violations could be found in either quantity, at least to well below the numerical accuracy where these violations were visible for the gluon propagator. The Coulomb potential from the A0 -propagator is shown to be in qualitative agreement with the (formally equivalent) expression evaluated from the Coulomb kernel.

  9. Heavy quarks, gluons and the confinement potential in Coulomb gauge

    SciTech Connect

    Popovici, Carina; Watson, Peter; Reinhardt, Hugo

    2011-05-23

    We consider the heavy quark limit of Coulomb gauge QCD, with the truncation of the Yang-Mills sector to include only (dressed) two-point functions. We find that the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is nonperturbatively exact and moreover, we provide a direct connection between the temporal gluon propagator and the quark confinement potential. Further, we show that only bound states of color singlet quark-antiquark (meson) and quark-quark (SU(2) baryon) pairs are physically allowed.

  10. The ghost propagator in Coulomb gauge

    SciTech Connect

    Watson, P.; Reinhardt, H.

    2011-05-23

    We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until 'forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

  11. The ghost propagator in Coulomb gauge

    NASA Astrophysics Data System (ADS)

    Watson, P.; Reinhardt, H.

    2011-05-01

    We present results for a numerical study of the ghost propagator in Coulomb gauge whereby lattice results for the spatial gluon propagator are used as input to solving the ghost Dyson-Schwinger equation. We show that in order to solve completely, the ghost equation must be supplemented by a boundary condition (the value of the inverse ghost propagator dressing function at zero momentum) which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until `forced' to freeze out in the infrared to the value of the boundary condition. The boundary condition can be interpreted in terms of the Gribov gauge-fixing ambiguity; we also demonstrate that this is not connected to the renormalization. Further, the connection to the temporal gluon propagator and the infrared slavery picture of confinement is discussed.

  12. Coulomb gauge ghost Dyson-Schwinger equation

    NASA Astrophysics Data System (ADS)

    Watson, P.; Reinhardt, H.

    2010-12-01

    A numerical study of the ghost Dyson-Schwinger equation in Coulomb gauge is performed and solutions for the ghost propagator found. As input, lattice results for the spatial gluon propagator are used. It is shown that in order to solve completely, the equation must be supplemented by a nonperturbative boundary condition (the value of the inverse ghost propagator dressing function at zero momentum), which determines if the solution is critical (zero value for the boundary condition) or subcritical (finite value). The various solutions exhibit a characteristic behavior where all curves follow the same (critical) solution when going from high to low momenta until forced to freeze out in the infrared to the value of the boundary condition. The renormalization is shown to be largely independent of the boundary condition. The boundary condition and the pattern of the solutions can be interpreted in terms of the Gribov gauge-fixing ambiguity. The connection to the temporal gluon propagator and the infrared slavery picture of confinement is explored.

  13. Lattice gauge theory for QCD

    SciTech Connect

    DeGrand, T.

    1997-06-01

    These lectures provide an introduction to lattice methods for nonperturbative studies of Quantum Chromodynamics. Lecture 1: Basic techniques for QCD and results for hadron spectroscopy using the simplest discretizations; lecture 2: Improved actions--what they are and how well they work; lecture 3: SLAC physics from the lattice-structure functions, the mass of the glueball, heavy quarks and {alpha}{sub s} (M{sub z}), and B-{anti B} mixing. 67 refs., 36 figs.

  14. Coulomb gauge model for hidden charm tetraquarks

    NASA Astrophysics Data System (ADS)

    Xie, W.; Mo, L. Q.; Wang, Ping; Cotanch, Stephen R.

    2013-08-01

    The spectrum of tetraquark states with hidden charm is studied within an effective Coulomb gauge Hamiltonian approach. Of the four independent color schemes, two are investigated, the (qcbar)1(cqbar)1 singlet-singlet (molecule) and the (qc)3(qbarcbar)3 triplet-triplet (diquark), for selected JPC states using a variational method. The predicted masses of triplet-triplet tetraquarks are roughly a GeV heavier than the singlet-singlet states. There is also an interesting flavor dependence with (qqbar)1 (ccbar1) states about half a GeV lighter than (qcbar)1(qbarc)1. The lightest 1++ and 1-- predictions are in agreement with the observed X (3872) and Y (4008) masses suggesting they are molecules with ωJ / ψ and ηhc, rather than D*Dbar* and DDbar, type structure, respectively. Similarly, the lightest isovector 1++ molecule, having a ρJ / ψ flavor composition, has mass near the recently observed charged Zc (3900) value. These flavor configurations are consistent with observed X, Y and Zc decays to ππJ / ψ.

  15. Gauge Configurations for Lattice QCD from The Gauge Connection

    DOE Data Explorer

    The Gauge Connection is an experimental archive for lattice QCD and a repository of gauge configurations made freely available to the community. Contributors to the archive include the Columbia QCDSP collaboration, the MILC collaboration, and others. Configurations are stored in QCD archive format, consisting of an ASCII header which defines various parameters, followed by binary data. NERSC has also provided some utilities and examples that will aid users in handling the data. Users may browse the archive, but are required to register for a password in order to download data. Contents of the archive are organized under four broad headings: Quenched (more than 1200 configurations); Dynamical, Zero Temperature (more than 300 configurations); MILC Improved Staggered Asqtad Lattices (more than 7000 configurations); and Dynamical, Finite Temperature (more than 1200 configurations)

  16. Renormalizability of a generalized gauge fixing interpolating among the Coulomb, Landau and maximal Abelian gauges

    SciTech Connect

    Capri, M.A.L. . E-mail: marcio@dft.if.uerj.br; Sobreiro, R.F. . E-mail: sobreiro@uerj.br; Sorella, S.P. . E-mail: sorella@uerj.br; Thibes, R. . E-mail: thibes@dft.if.uerj.br

    2007-08-15

    A detailed discussion of the renormalization properties of a class of gauges which interpolates among the Landau, Coulomb and maximal Abelian gauges is provided in the framework of the algebraic renormalization in Euclidean Yang-Mills theories in four dimensions.

  17. Running Coulomb potential and Lamb shift in QCD

    SciTech Connect

    Hoang, Andre H.; Manohar, Aneesh V.; Stewart, Iain W.

    2001-07-01

    The QCD {beta} function and the anomalous dimensions for the Coulomb potential and the static potential first differ at three loop order. We evaluate the three loop ultrasoft anomalous dimension for the Coulomb potential and give the complete three loop running. Using this result, we calculate the leading logarithmic Lamb shift for a heavy-quark{endash}antiquark bound state, which includes all contributions to the binding energies of the form m{alpha}{sub s}{sup 4}({alpha}{sub s}ln{alpha}{sub s}){sup k}, k{ge}0.

  18. Gribov horizon and Gribov copies effect in lattice Coulomb gauge

    NASA Astrophysics Data System (ADS)

    Burgio, Giuseppe; Quandt, Markus; Reinhardt, Hugo; Vogt, Hannes

    2017-01-01

    Following a recent proposal by Cooper and Zwanziger, we investigate via S U (2 ) lattice simulations the effect on the Coulomb gauge propagators and on the Gribov-Zwanziger confinement mechanism of selecting the Gribov copy with the smallest nontrivial eigenvalue of the Faddeev-Popov operator, i.e., the one closest to the Gribov horizon. Although such choice of gauge drives the ghost propagator towards the prediction of continuum calculations, we find that it actually overshoots the goal. With increasing computer time, we observe that Gribov copies with arbitrarily small eigenvalues can be found. For such a method to work, one would therefore need further restrictions on the gauge condition to isolate the physically relevant copies, since, for example, the Coulomb potential VC defined through the Faddeev-Popov operator becomes otherwise physically meaningless. Interestingly, the Coulomb potential alternatively defined through temporal link correlators is only marginally affected by the smallness of the eigenvalues.

  19. On the Nonlocality of the Coulomb Gauge External Field Problem

    NASA Astrophysics Data System (ADS)

    Hraskó, Péter

    The apparent nonlocality of the Coulomb gauge external field problem in electrodynamics is illustrated with an example in which nonlocality is especially striking. Explanation of this apparent nonlocal behaviour based on a purely local picture is given. A gauge invariant decomposition of the Lorentz-force into two terms with clear physical meanings is pointed out. Based on this decomposition derivation of the Aharonov-Bohm effect in terms of field strengths alone is given.

  20. On the nonlocality of the Coulomb gauge external field problem

    NASA Astrophysics Data System (ADS)

    Hraskó, Péter

    2016-10-01

    The apparent nonlocality of the Coulomb gauge external field problem in electrodynamics is illustrated with an example in which nonlocality is especially striking. Explanation of this apparent nonlocal behaviour based on a purely local picture is given. A gauge invariant decomposition of the Lorentz-force into two terms with clear physical meanings is pointed out. Based on this decomposition derivation of the Aharonov-Bohm effect in terms of field strengths alone is given.

  1. Instabilities of Coulomb phases and quark confinement in QCD

    SciTech Connect

    Asorey, Manuel; Santagata, Alessandro

    2009-01-01

    The Gribov picture to quark confinement is based on the Coulomb phase instability due to the very large values that the effective α{sub s} coupling constant can reach in the infrared regime. The Gribov instability is driven by a vacuum decay into light quarks beyond a critical value of the coupling constant α{sub s}3π(1-√(2/3))/4 (for SU(3) gauge group). From first principles it has been shown the existence of an instability of the Coulomb phase in pure gauge theories for α≥√(2), much beyond the Gribov critical value. In this paper we analyze the effect of dynamical quarks in the instability of the Coulomb phase. We find a critical value of the coupling α=√(3) where a quark-antiquark pair creation mechanism leads to vacuum instability. However, the new critical value turns out to be larger than the pure gauge critical value α=√(2), unlike it is expected in the standard Gribov scenario. The result is analytically derived from first principles and provides further consistency to the picture where quark confinement is mainly driven by gluonic fluctuation instabilities.

  2. Hamiltonian flow in Coulomb gauge Yang-Mills theory

    SciTech Connect

    Leder, Markus; Reinhardt, Hugo; Pawlowski, Jan M.; Weber, Axel

    2011-01-15

    We derive a new functional renormalization group equation for Hamiltonian Yang-Mills theory in Coulomb gauge. The flow equations for the static gluon and ghost propagators are solved under the assumption of ghost dominance within different diagrammatic approximations. The results are compared to those obtained in the variational approach and the reliability of the approximations is discussed.

  3. Ice limit of Coulomb gauge Yang-Mills theory

    SciTech Connect

    Heinzl, T.; Ilderton, A.; Langfeld, K.; Lavelle, M.; McMullan, D.

    2008-10-01

    In this paper we describe gauge invariant multiquark states generalizing the path integral framework developed by Parrinello, Jona-Lasinio, and Zwanziger to amend the Faddeev-Popov approach. This allows us to produce states such that, in a limit which we call the ice limit, fermions are dressed with glue exclusively from the fundamental modular region associated with Coulomb gauge. The limit can be taken analytically without difficulties, avoiding the Gribov problem. This is illustrated by an unambiguous construction of gauge invariant mesonic states for which we simulate the static quark-antiquark potential.

  4. Gauge Theories on the Coulomb Branch

    NASA Astrophysics Data System (ADS)

    Schwarz, John H.

    We construct the world-volume action of a probe D3-brane in AdS5 × S5 with N units of flux. It has the field content, symmetries, and dualities of the U(1) factor of 𝒩 = 4 U(N + 1) super Yang-Mills theory, spontaneously broken to U(N) × U(1) by being on the Coulomb branch, with the massive fields integrated out. This motivates the conjecture that it is the exact effective action, called a highly effective action (HEA). We construct an SL(2, Z) multiplet of BPS soliton solutions of the D3-brane theory (the conjectured HEA) and show that they reproduce the electrically charged massive states that have been integrated out as well as magnetic monopoles and dyons. Their charges are uniformly spread on a spherical surface, called a soliton bubble, which is interpreted as a phase boundary.

  5. Infrared Behavior and Fixed Points in Landau-Gauge QCD

    NASA Astrophysics Data System (ADS)

    Pawlowski, Jan M.; Litim, Daniel F.; Nedelko, Sergei; von Smekal, Lorenz

    2004-10-01

    We investigate the infrared behavior of gluon and ghost propagators in Landau-gauge QCD by means of an exact renormalization group equation. We explain how, in general, the infrared momentum structure of Green functions can be extracted within this approach. An optimization procedure is devised to remove residual regulator dependences. In Landau-gauge QCD this framework is used to determine the infrared leading terms of the propagators. The results support the Kugo-Ojima confinement scenario. Possible extensions are discussed.

  6. Coulomb-Gauge Gluon Propagator and the Gribov Formula

    SciTech Connect

    Burgio, G.; Quandt, M.; Reinhardt, H.

    2009-01-23

    We analyze the lattice SU(2) Yang-Mills theory in the Coulomb gauge. We show that the static gluon propagator is multiplicative renormalizable and takes the simple form D(|p-vector|){sup -1}={radical}(|p-vector|{sup 2}+M{sup 4}/|p-vector|{sup 2}), proposed by Gribov through heuristic arguments many years ago. We find M=0.88(1) GeV{approx_equal}2{radical}({sigma})

  7. Infrared suppression of the Coulomb gauge gluon propagator in SU(3) Yang-Mills theory

    NASA Astrophysics Data System (ADS)

    Nakagawa, Y.

    We calculate the equal-time transverse gluon propagator in Coulomb gauge QCD using a SU(3) quenched lattice gauge simulation on large lattices, up to 114 [fm4 ]. We find that the equal-time gluon propagator shows scaling violation; namely, the data for different lattice spacings do not fall on top of one curve. This problem is cured by discarding data at large momenta, which suffer from discretization errors. In the infrared region, the transverse gluon propagator is strongly suppressed and shows a turnover at about 500 [MeV]. Fitting the power law ansatz to the data at small momenta predicts the vanishing gluon propagator at zero momentum, indicating the confinement of gluons.

  8. QCD, monopoles on the lattice and gauge invariance

    SciTech Connect

    Bonati, C.; Di Giacomo, A.; D'Elia, M.

    2011-05-23

    The number and the location of the monopoles observed on the lattice in QCD configurations happens to depend strongly on the choice of the gauge used to expose them, in contrast to the physical expectation that monopoles be gauge invariant objects. It is proved by use of the non abelian Bianchi identities (NABI) that monopoles are indeed gauge invariant, but the method used to detect them depends, in a controllable way, on the choice of the abelian projection. Numerical checks are presented.

  9. Volume Independence in Large Nc QCD-like Gauge Theories

    SciTech Connect

    Kovtun, Pavel; Unsal, Mithat; Yaffe, Laurence G.

    2007-02-06

    Volume independence in large N{sub c} gauge theories may be viewed as a generalized orbifold equivalence. The reduction to zero volume (or Eguchi-Kawai reduction) is a special case of this equivalence. So is temperature independence in confining phases. A natural generalization concerns volume independence in ''theory space'' of quiver gauge theories. In pure Yang-Mills theory, the failure of volume independence for sufficiently small volumes (at weak coupling) due to spontaneous breaking of center symmetry, together with its validity above a critical size, nicely illustrate the symmetry realization conditions which are both necessary and sufficient for large N{sub c} orbifold equivalence. The existence of a minimal size below which volume independence fails also applies to Yang-Mills theory with antisymmetric representation fermions [QCD(AS)]. However, in Yang-Mills theory with adjoint representation fermions [QCD(Adj)], endowed with periodic boundary conditions, volume independence remains valid down to arbitrarily small size. In sufficiently large volumes, QCD(Adj) and QCD(AS) have a large N{sub c} ''orientifold'' equivalence, provided charge conjugation symmetry is unbroken in the latter theory. Therefore, via a combined orbifold-orientifold mapping, a well-defined large N{sub c} equivalence exists between QCD(AS) in large, or infinite, volume and QCD(Adj) in arbitrarily small volume. Since asymptotically free gauge theories, such as QCD(Adj), are much easier to study (analytically or numerically) in small volume, this equivalence should allow greater understanding of large N{sub c} QCD in infinite volume.

  10. Gauge/String Duality, Hot QCD and Heavy Ion Collisions

    NASA Astrophysics Data System (ADS)

    Casalderrey-Solana, Jorge; Liu, Hong; Mateos, David; Rajagopal, Krishna; Wiedemann, Urs Achim

    2014-06-01

    1. Opening remarks; 2. A heavy ion phenomenology primer; 3. Results from lattice QCD at nonzero temperature; 4. Introducing the gauge/string duality; 5. A duality toolbox; 6. Bulk properties of strongly coupled plasma; 7. From hydrodynamics for far-from-equilibrium dynamics; 8. Probing strongly coupled plasma; 9. Quarkonium mesons in strongly coupled plasma; 10. Concluding remarks and outlook; Appendixes; References; Index.

  11. Coulomb gauge confinement in the heavy quark limit

    SciTech Connect

    Popovici, C.; Watson, P.; Reinhardt, H.

    2010-05-15

    The relationship between the nonperturbative Green's functions of Yang-Mills theory and the confinement potential is investigated. By rewriting the generating functional of quantum chromodynamics in terms of a heavy quark mass expansion in Coulomb gauge, restricting to leading order in this expansion and considering only the two-point functions of the Yang-Mills sector, the rainbow-ladder approximation to the gap and Bethe-Salpeter equations is shown to be exact in this case and an analytic, nonperturbative solution is presented. It is found that there is a direct connection between the string tension and the temporal gluon propagator. Further, it is shown that for the 4-point quark correlation functions, only confined bound states of color-singlet quark-antiquark (meson) and quark-quark (baryon) pairs exist.

  12. Gribov pendulum in the Coulomb gauge on curved spaces

    NASA Astrophysics Data System (ADS)

    Canfora, Fabrizio; Giacomini, Alex; Oliva, Julio

    2011-11-01

    In this paper the generalization of the Gribov pendulum equation in the Coulomb gauge for curved space-times is analyzed on static spherically symmetric backgrounds. A rigorous argument for the existence and uniqueness of solution is provided in the asymptotically AdS case. The analysis of the strong and weak boundary conditions is equivalent to analyzing an effective one-dimensional Schrödinger equation. Necessary conditions in order for spherically symmetric backgrounds to admit solutions of the Gribov pendulum equation representing copies of the vacuum satisfying the strong boundary conditions are given. It is shown that asymptotically flat backgrounds do not support solutions of the Gribov pendulum equation of this type, while on asymptotically AdS backgrounds such ambiguities can appear. Some physical consequences are discussed.

  13. Coulomb branches for rank 2 gauge groups in 3 d N=4 gauge theories

    NASA Astrophysics Data System (ADS)

    Hanany, Amihay; Sperling, Marcus

    2016-08-01

    The Coulomb branch of 3-dimensional N=4 gauge theories is the space of bare and dressed BPS monopole operators. We utilise the conformal dimension to define a fan which, upon intersection with the weight lattice of a GNO-dual group, gives rise to a collection of semi-groups. It turns out that the unique Hilbert bases of these semi-groups are a sufficient, finite set of monopole operators which generate the entire chiral ring. Moreover, the knowledge of the properties of the minimal generators is enough to compute the Hilbert series explicitly. The techniques of this paper allow an efficient evaluation of the Hilbert series for general rank gauge groups. As an application, we provide various examples for all rank two gauge groups to demonstrate the novel interpretation.

  14. Light-Front-Quantized QCD in Light-Cone Gauge

    SciTech Connect

    Brodsky, Stanley J.

    2000-11-30

    The light-front (LF) quantization of QCD in light-cone gauge has a number of remarkable advantages, including explicit unitarity, a physical Fock expansion, the absence of ghost degrees of freedom, and the decoupling properties needed to prove factorization theorems in high momentum transfer inclusive and exclusive reactions. We present a systematic study of LF-quantized gauge theory following the Dirac method and construct the Dyson-Wick S-matrix expansion based on LF-time-ordered products. The gauge field is shown to satisfy the Lorentz condition as an operator equation as well as the light-cone gauge condition. Its propagator is found to be transverse with respect to both its four-momentum and the gauge direction. The propagator of the dynamical + part of the free fermionic field is shown to be causal and to not contain instantaneous terms. The interaction Hamiltonian of QCD can be expressed in a form resembling that of covariant theory, except for additional instantaneous interactions which can be treated systematically. The renormalization factors are shown to be scalars and we find Z1 = Z3 at one loop order. The running coupling constant and QCD {beta} function are also computed in the noncovariant light-cone gauge. Some comments on the relationship of our LF framework to the analytic effective charge and renormalization scheme defined by the pinch technique are made. LF quantization thus provides a consistent formulation of gauge theory, despite the fact that the hyperplanes x{sup {+-}} = 0 used to impose boundary conditions constitute characteristic surfaces of a hyperbolic partial differential equation.

  15. Lattice QCD with the overlap fermions at strong gauge coupling

    NASA Astrophysics Data System (ADS)

    Ichinose, Ikuo; Nagao, Keiichi

    2000-06-01

    We generalize overlap fermion by Narayanan and Neuberger by introducing a hopping parameter t . This lattice fermion has desirable properties as the original overlap fermion. We expand "Dirac" operator of this fermion in powers of t . Higher-order terms of t are long-distance terms and this t -expansion is a kind of the hopping expansion. It is shown that the Ginsparg-Wilson relation is satisfied at each order of t . We show that this t -expansion is useful for study of the strong-coupling gauge theory. We apply this formalism to the lattice QCD and study its chiral phase structure at strong coupling. We find that there are (at least) two phases one of which has desired chiral properties of QCD. Possible phase structure of the lattice QCD with the overlap fermions is proposed.

  16. Light-front-quantized QCD in Covariant Gauge

    SciTech Connect

    Srivastava, Prem P.

    1999-06-17

    The light-front (LF) canonical quantization of quantum chromodynamics in covariant gauge is discussed. The Dirac procedure is used to eliminate the constraints in the gauge-fixed front form theory quantum action and to construct the LF Hamiltonian formulation. The physical degrees of freedom emerge naturally. The propagator of the dynamical {psi}{sub +} part of the free fermionic propagator in the LF quantized field theory is shown to be causal and not to contain instantaneous terms. Since the relevant propagators in the covariant gauge formulation are causal, rotational invariance--including the Coulomb potential in the static limit--can be recovered, avoiding the difficulties encountered in light-cone gauge. The Wick rotation may also be performed allowing the conversion of momentum space integrals into Euclidean space forms. Some explicit computations are done in quantum electrodynamics to illustrate the equivalence of front form theory with the conventional covariant formulation. LF quantization thus provides a consistent formulation of gauge theory, despite the fact that the hyperplanes x{sup {+-}} = 0 used to impose boundary conditions constitute characteristic surfaces of a hyperbolic partial differential equation.

  17. Direct evidence for a Coulombic phase in monopole-suppressed SU(2) lattice gauge theory

    NASA Astrophysics Data System (ADS)

    Grady, Michael

    2013-11-01

    Further evidence is presented for the existence of a non-confining phase at weak coupling in SU(2) lattice gauge theory. Using Monte Carlo simulations with the standard Wilson action, gauge-invariant SO(3)-Z2 monopoles, which are strong-coupling lattice artifacts, have been seen to undergo a percolation transition exactly at the phase transition previously seen using Coulomb gauge methods, with an infinite lattice critical point near β=3.2. The theory with both Z2 vortices and monopoles and SO(3)-Z2 monopoles eliminated is simulated in the strong-coupling (β=0) limit on lattices up to 604. Here, as in the high-β phase of the Wilson-action theory, finite size scaling shows it spontaneously breaks the remnant symmetry left over after Coulomb gauge fixing. Such a symmetry breaking precludes the potential from having a linear term. The monopole restriction appears to prevent the transition to a confining phase at any β. Direct measurement of the instantaneous Coulomb potential shows a Coulombic form with moderately running coupling possibly approaching an infrared fixed point of α˜1.4. The Coulomb potential is measured to 50 lattice spacings and 2 fm. A short-distance fit to the 2-loop perturbative potential is used to set the scale. High precision at such long distances is made possible through the use of open boundary conditions, which was previously found to cut random and systematic errors of the Coulomb gauge fixing procedure dramatically. The Coulomb potential agrees with the gauge-invariant interquark potential measured with smeared Wilson loops on periodic lattices as far as the latter can be practically measured with similar statistics data.

  18. Hamiltonian Approach to Yang-Mills Theory in Coulomb Gauge--Revisited

    SciTech Connect

    Reinhardt, Hugo; Campagnari, Davide R.; Leder, Markus; Burgio, Giuseppe; Quandt, Markus; Pawlowski, Jan M.; Weber, Axel

    2011-05-24

    I briefly review results obtained within the variational Hamiltonian approach to Yang-Mills theory in Coulomb gauge and confront them with recent lattice data. The variational approach is extended to non-Gaussian wave functionals including three- and four-gluon kernels in the exponential of the vacuum wave functional and used to calculate the three-gluon vertex. A new functional renormalization group flow equation for Hamiltonian Yang-Mills theory in Coulomb gauge is solved for the gluon and ghost propagator under the assumption of ghost dominance. The results are compared to those obtained in the variational approach.

  19. Hamiltonian Dyson-Schwinger and FRG Flow Equations of Yang-Mills Theory in Coulomb Gauge

    SciTech Connect

    Reinhardt, Hugo; Leder, Markus; Pawlowski, Jan M.; Weber, Axel

    2011-05-23

    A new functional renormalization group equation for Hamiltonian Yang-Mills theory in Coulomb gauge is presented and solved for the static gluon and ghost propagators under the assumption of ghost dominance. The results are compared to those obtained in the variational approach.

  20. Modified Coulomb and Lorenz gauges in the modeling of low- frequency electromagnetic processes

    NASA Astrophysics Data System (ADS)

    Kalinin, A. V.; Tiukhtina, A. A.; Lavrova, S. R.

    2016-11-01

    The boundary value problem for the quasistationary magnetic approximation of the time-harmonic Maxwell equations in inhomogeneous media is studied. The considered problem is reduced to the variational problem of determining vector magnetic and scalar electric potentials. The special gauges are discussed, that generalize the Coulomb and Lorenz gauges and allow to formulate the problems of the independent definitions of the vector magnetic potential. The correctness of the problems are established under general conditions on the coefficients. The relation between solutions of the problems with different gauges is studied. The equivalence of the problems for potentials to the original boundary value problem is proved.

  1. Perturbation theory in the Hamiltonian approach to Yang-Mills theory in Coulomb gauge

    SciTech Connect

    Campagnari, Davide R.; Reinhardt, Hugo; Weber, Axel

    2009-07-15

    We study the Hamiltonian approach to Yang-Mills theory in Coulomb gauge in Rayleigh-Schroedinger perturbation theory. The static gluon and ghost propagator as well as the potential between static color sources are calculated to one-loop order. Furthermore, the one-loop {beta} function is calculated from both the ghost-gluon vertex and the static potential and found to agree with the result of covariant perturbation theory.

  2. Scalar vertex operator for bound-state QED in the Coulomb gauge

    SciTech Connect

    Holmberg, Johan

    2011-12-15

    Adkins's result [Phys. Rev. D 34, 2489 (1986)] for the time component of the renormalized vertex operator in Coulomb-gauge QED is separated according to its tensor structure and some of the Feynman parameter integrals are carried out analytically, yielding a form suited for numerical bound-state QED calculations. This modified form is applied to the evaluation of the self-energy shift to the binding energy in hydrogenic ions of high nuclear charge.

  3. Twenty-first Century Lattice Gauge Theory: Results from the QCD Lagrangian

    SciTech Connect

    Kronfeld, Andreas S.; /Fermilab

    2012-03-01

    Quantum chromodynamics (QCD) reduces the strong interactions, in all their variety, to an elegant nonabelian gauge theory. It clearly and elegantly explains hadrons at short distances, which has led to its universal acceptance. Since its advent, however, many of its long-distance, emergent properties have been believed to be true, without having been demonstrated to be true. This paper reviews a variety of results in this regime that have been established with lattice gauge theory, directly from the QCD Lagrangian. This body of work sheds light on the origin of hadron masses, its interplay with dynamical symmetry breaking, as well as on other intriguing features such as the phase structure of QCD. In addition, nonperturbative QCD is quantitatively important to many aspects of particle physics (especially the quark flavor sector), nuclear physics, and astrophysics. This review also surveys some of the most interesting connections to those subjects.

  4. Generating SU(Nc) pure gauge lattice QCD configurations on GPUs with CUDA

    NASA Astrophysics Data System (ADS)

    Cardoso, Nuno; Bicudo, Pedro

    2013-03-01

    The starting point of any lattice QCD computation is the generation of a Markov chain of gauge field configurations. Due to the large number of lattice links and due to the matrix multiplications, generating SU(Nc) lattice QCD configurations is a highly demanding computational task, requiring advanced computer parallel architectures such as clusters of several Central Processing Units (CPUs) or Graphics Processing Units (GPUs). In this paper we present and explore the performance of CUDA codes for NVIDIA GPUs to generate SU(Nc) lattice QCD pure gauge configurations. Our implementation in one GPU uses CUDA and in multiple GPUs uses OpenMP and CUDA. We present optimized CUDA codes for SU(2), SU(3) and SU(4). We also show a generic SU(Nc) code for Nc≥4 and compare it with the optimized version of SU(4). Our codes are publicly available for free use by the lattice QCD community.

  5. Localizing gauge fields on a topological Abelian string and the Coulomb law

    SciTech Connect

    Torrealba S, Rafael S.

    2010-07-15

    The confinement of electromagnetic field is studied in axial symmetrical, warped, six-dimensional brane world, using a recently proposed topological Abelian string-vortex solution as background. It was found, that the massless gauge field fluctuations follow four-dimensional Maxwell equations in the Lorenz gauge. The massless zero mode is localized when the thickness of the string vortex is less than 5{beta}/4{pi}e{sup 2}v{sup 2} and there are no other localized massless modes. There is also an infinite of nonlocalized massive Fourier modes, that follow four-dimensional Proca equations with a continuous spectrum. To compute the corrections to the Coulomb potential, a radial cutoff was introduced, in order to achieve a discrete mass spectrum. As a main result, a (R{sub o}/{beta}R{sup 2}) correction was found for the four-dimensional effective Coulomb law; the result is in correspondence with the observed behavior of the Coulomb potential at today's measurable distances.

  6. Dimension two condensates in the Gribov-Zwanziger theory in Coulomb gauge

    NASA Astrophysics Data System (ADS)

    Guimaraes, M. S.; Mintz, B. W.; Sorella, S. P.

    2015-06-01

    We investigate the dimension two condensate ⟨ϕ¯ia bϕia b-ω¯ia bωia b⟩ within the Gribov-Zwanziger approach to Euclidean Yang-Mills theories in the Coulomb gauge, in both 3 and 4 dimensions. An explicit calculation shows that, at the first order, the condensate ⟨ϕ¯i a bϕia b-ω¯i a bωia b⟩ is plagued by a nonintegrable IR divergence in 3 D , while in 4 D it exhibits a logarithmic UV divergence, being proportional to the Gribov parameter γ2. These results indicate that in 3D the transverse spatial Coulomb gluon two-point correlation function exhibits a scaling behavior, in agreement with Gribov's expression. In 4D, however, they suggest that, next to the scaling behavior, a decoupling solution might emerge too.

  7. QCD and strongly coupled gauge theories: challenges and perspectives.

    PubMed

    Brambilla, N; Eidelman, S; Foka, P; Gardner, S; Kronfeld, A S; Alford, M G; Alkofer, R; Butenschoen, M; Cohen, T D; Erdmenger, J; Fabbietti, L; Faber, M; Goity, J L; Ketzer, B; Lin, H W; Llanes-Estrada, F J; Meyer, H B; Pakhlov, P; Pallante, E; Polikarpov, M I; Sazdjian, H; Schmitt, A; Snow, W M; Vairo, A; Vogt, R; Vuorinen, A; Wittig, H; Arnold, P; Christakoglou, P; Di Nezza, P; Fodor, Z; Garcia I Tormo, X; Höllwieser, R; Janik, M A; Kalweit, A; Keane, D; Kiritsis, E; Mischke, A; Mizuk, R; Odyniec, G; Papadodimas, K; Pich, A; Pittau, R; Qiu, J-W; Ricciardi, G; Salgado, C A; Schwenzer, K; Stefanis, N G; von Hippel, G M; Zakharov, V I

    We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to strongly coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.

  8. QCD and strongly coupled gauge theories: Challenges and perspectives

    DOE PAGES

    Brambilla, N.; Eidelman, S.; Foka, P.; ...

    2014-10-21

    We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to stongly-coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many researchmore » streams which flow into and out of QCD, as well as a vision for future developments.« less

  9. QCD and strongly coupled gauge theories: Challenges and perspectives

    SciTech Connect

    Brambilla, N.; Eidelman, S.; Foka, P.; Gardner, S.; Kronfeld, A. S.; Alford, M. G.; Alkofer, R.; Butenschoen, M.; Cohen, T. D.; Erdmenger, J.; Fabbietti, L.; Faber, M.; Goity, J. L.; Ketzer, B.; Lin, H. W.; Llanes-Estrada, F. J.; Meyer, H. B.; Pakhlov, P.; Pallante, E.; Polikarpov, M. I.; Sazdjian, H.; Schmitt, A.; Snow, W. M.; Vairo, A.; Vogt, R.; Vuorinen, A.; Wittig, H.; Arnold, P.; Christakoglou, P.; Di Nezza, P.; Fodor, Z.; Garcia i Tormo, X.; Höllwieser, R.; Janik, M. A.; Kalweit, A.; Keane, D.; Kiritsis, E.; Mischke, A.; Mizuk, R.; Odyniec, G.; Papadodimas, K.; Pich, A.; Pittau, R.; Qiu, J. -W.; Ricciardi, G.; Salgado, C. A.; Schwenzer, K.; Stefanis, N. G.; von Hippel, G. M.; Zakharov, V. I.

    2014-10-21

    We highlight the progress, current status, and open challenges of QCD-driven physics, in theory and in experiment. We discuss how the strong interaction is intimately connected to a broad sweep of physical problems, in settings ranging from astrophysics and cosmology to stongly-coupled, complex systems in particle and condensed-matter physics, as well as to searches for physics beyond the Standard Model. We also discuss how success in describing the strong interaction impacts other fields, and, in turn, how such subjects can impact studies of the strong interaction. In the course of the work we offer a perspective on the many research streams which flow into and out of QCD, as well as a vision for future developments.

  10. Brief remarks on the similarities of the infrared solutions for the ghost propagator Dyson-Schwinger equation in Landau and Coulomb gauges

    SciTech Connect

    Rodriguez-Quintero, J.

    2011-05-01

    This brief note is devoted to reconcile the conclusions from a recent analysis of the IR solutions for the ghost propagator Dyson-Schwinger equations in Coulomb gauge with previous studies in Landau gauge.

  11. Gauge-symmetric approach to effective lagrangians: The η' meson from QCD

    NASA Astrophysics Data System (ADS)

    Damgaard, P. H.; Nielsen, H. B.; Sollacher, R.

    1994-02-01

    We present a general scheme for extracting effective degrees of freedom from an underlying fundamental lagrangian, through a series of well-defined transformations in the functional integral of the cut-off theory. This is done by introducing collective fields in a gauge-symmetric manner. Through appropriate gauge fixings of this symmetry one can remove long-distance degrees of freedom from the underlying theory, replacing them by the collective fields. Applying this technique to QCD, we set out to extract the long-distance dynamics in the pseudoscalar flavour singlet sector through a gauging (and subsequent gauge fixing) of the U (1) A flavour symmetry which is broken by the anomaly. By this series of exact transformations of a cut-off generating functional for QCD, we arrive at a theory describing the long-distance physics of a pseudoscalar flavour singlet meson coupled to the residual quark-gluon degrees of freedom. As an example we show how to derive a Witten-Veneziano-like relation between the η' mass and the topological susceptibility. The resulting effective lagrangian contains an axial vector field, which shares the relevant features with the Veneziano ghost. This field is responsible for removing the η' degree of freedom from the fundamental QCD lagrangian.

  12. Metastable vacuum decay and θ dependence in gauge theory. Deformed QCD as a toy model

    NASA Astrophysics Data System (ADS)

    Bhoonah, Amit; Thomas, Evan; Zhitnitsky, Ariel R.

    2015-01-01

    We study a number of different ingredients related to the θ dependence, metastable excited vacuum states and other related subjects using a simplified version of QCD, the so-called "deformed QCD". This model is a weakly coupled gauge theory, which, however, preserves all the relevant essential elements allowing us to study hard and nontrivial features which are known to be present in real strongly coupled QCD. Our main focus in this work is to test the ideas related to the metastable vacuum states (which are known to be present in strongly coupled QCD in large N limit) in a theoretically controllable manner using the "deformed QCD" as a toy model. We explicitly show how the metastable states emerge in the system, why their lifetime is large, and why these metastable states must be present in the system for the self-consistency of the entire picture of the QCD vacuum. We also speculate on possible relevance of the metastable vacuum states in explanation of the violation of local P and CP symmetries in heavy ion collisions.

  13. The gauge invariant quark Green's function in two-dimensional QCD

    SciTech Connect

    Sazdjian, H.

    2010-12-22

    The gauge invariant quark Green's function, defined with a path-ordered phase factor along a straight-line, is studied in two-dimensional QCD in the large-N{sub c} limit by means of an exact integrodifferential equation. It is found to be infrared finite with singularities represented by an infinite number of threshold type branch points with a power of -3/2, starting at positive mass squared values. The Green's function is analytically determined.

  14. Coulomb-gauge ghost and gluon propagators in SU(3) lattice Yang-Mills theory

    NASA Astrophysics Data System (ADS)

    Nakagawa, Y.; Voigt, A.; Ilgenfritz, E.-M.; Müller-Preussker, M.; Nakamura, A.; Saito, T.; Sternbeck, A.; Toki, H.

    2009-06-01

    We study the momentum dependence of the ghost propagator and of the space and time components of the gluon propagator at equal time in pure SU(3) lattice Coulomb-gauge theory carrying out a joint analysis of data collected independently at the Research Center for Nuclear Physics, Osaka and Humboldt University, Berlin. We focus on the scaling behavior of these propagators at β=5.8,…,6.2 and apply a matching technique to relate the data for the different lattice cutoffs. Thereby, lattice artifacts are found to be rather strong for both instantaneous gluon propagators at a large momentum. As a byproduct we obtain the respective lattice scale dependences a(β) for the transversal gluon and the ghost propagator which indeed run faster with β than two-loop running, but slightly slower than what is known from the Necco-Sommer analysis of the heavy quark potential. The abnormal a(β) dependence as determined from the instantaneous time-time gluon propagator, D44, remains a problem, though. The role of residual gauge-fixing influencing D44 is discussed.

  15. A new, analytic, non-perturbative, gauge-invariant formulation of realistic QCD

    NASA Astrophysics Data System (ADS)

    Fried, H. M.; Grandou, T.; Gabellini, Y.; Sheu, Y.-M.

    2012-09-01

    This Formulation [1], [2], [3] is New, in the sense that it is less than 3 years old. But it could have been done decades ago, since the input information existed, but was overlooked. It is Analytic in the sense that physically-reasonable approximations can be estimated with paper and pencil; and exact amplitudes can be calculated as Meijer G-functions of various orders. It is Non-Perturbative in the sense that sums over all possible gluon exchanges between any pair of quarks and/or antiquarks, including cubic and quartic gluon interactions, are exactly performed. These multiple gluon exchanges combine into "Gluon Bundles" (GBs), as sums over Feynman graphs with finite numbers of exchanged gluons are replaced by "Bundle Graphs". In effect, gluons disappear from the formalism, and GBs remain as the effective carrier of all interactions between quark lines. A simple re-arrangement of the Schwinger/Symanzik functional solution for the Generating Functional of QCD - a rearrangement possible in QCD but not in QED - produces a formal statement of Gauge-Invariance, even though the formulation contains gauge-dependent gluon propagators. After the non-perturbative sums produce GBs, one sees explicit cancelation of all gauge-dependent gluon propagators; gauge-invariance is achieved as gauge-independence. A new insight into Realistic QCD appears in the non-perturbative domain, because quarks do not have individual asymptotic states; they are always asymptotically bound, and their transverse coordinates cannot, in principle, be measured exactly. "Transverse Imprecision" is introduced into the basic Lagrangian, and quark-binding potentials for the construction of mesons and nucleons can then be defined and evaluated. And the greatest surprise of all: A new, non-perturbative property appears, called Effective Locality, with the result that all functional integrals reduce to (a few) sets of ordinary integrals, easy to estimate approximately, or calculate on a desk-top computer. A

  16. A new, analytic, non-perturbative, gauge-invariant formulation of realistic QCD

    SciTech Connect

    Fried, H. M.; Grandou, T.; Gabellini, Y.; Sheu, Y.-M.

    2012-09-26

    This Formulation [1], [2], [3] is New, in the sense that it is less than 3 years old. But it could have been done decades ago, since the input information existed, but was overlooked. It is Analytic in the sense that physically-reasonable approximations can be estimated with paper and pencil; and exact amplitudes can be calculated as Meijer G-functions of various orders. It is Non-Perturbative in the sense that sums over all possible gluon exchanges between any pair of quarks and/or antiquarks, including cubic and quartic gluon interactions, are exactly performed. These multiple gluon exchanges combine into 'Gluon Bundles' (GBs), as sums over Feynman graphs with finite numbers of exchanged gluons are replaced by {sup B}undle Graphs{sup .} In effect, gluons disappear from the formalism, and GBs remain as the effective carrier of all interactions between quark lines. A simple re-arrangement of the Schwinger/Symanzik functional solution for the Generating Functional of QCD - a rearrangement possible in QCD but not in QED - produces a formal statement of Gauge-Invariance, even though the formulation contains gauge-dependent gluon propagators. After the non-perturbative sums produce GBs, one sees explicit cancelation of all gauge-dependent gluon propagators; gauge-invariance is achieved as gauge-independence. A new insight into Realistic QCD appears in the non-perturbative domain, because quarks do not have individual asymptotic states; they are always asymptotically bound, and their transverse coordinates cannot, in principle, be measured exactly. 'Transverse Imprecision' is introduced into the basic Lagrangian, and quark-binding potentials for the construction of mesons and nucleons can then be defined and evaluated. And the greatest surprise of all: A new, non-perturbative property appears, called Effective Locality, with the result that all functional integrals reduce to (a few) sets of ordinary integrals, easy to estimate approximately, or calculate on a desk

  17. Heavy quark free energy in QCD and in gauge theories with gravity duals

    SciTech Connect

    Noronha, Jorge

    2010-09-15

    Recent lattice results in pure glue SU(3) theory at high temperatures have shown that the expectation value of the renormalized Polyakov loop approaches its asymptotic limit at high temperatures from above. We show that this implies that the 'heavy quark free energy' obtained from the renormalized loop computed on the lattice does not behave like a true thermodynamic free energy. While this should be expected to occur in asymptotically free gauge theories such as QCD, we use the gauge/string duality to show that in a large class of strongly coupled gauge theories with nontrivial UV fixed points the Polyakov loop reaches its asymptotic value from above only if the dimension of the relevant operator used to deform the conformal field theory is greater than or equal to 3.

  18. Quenched domain wall QCD with DBW2 gauge action toward nucleon decay matrix element calculation

    NASA Astrophysics Data System (ADS)

    Aoki, Yasumichi

    2001-10-01

    The domain wall fermion action is a promising way to control chiral symmetry in lattice gauge theory. By the good chiral symmetry of this approach even at finite lattice spacing, one is able to extract hadronic matrix elements, like kaon weak matrix elements, for which the symmetry is extremely important. Ordinary fermions with poor chiral symmetry make calculation difficult because of the large mixing of operators with different chiral structure. Even though the domain wall fermion action with the simple Wilson gauge action has a good chiral symmetry, one can further improve the symmetry by using a different gauge action. We take a non-perturbatively improved action, the DBW2 action of the QCD Taro group. Hadron masses are systematically examined for a range of parameters. Application to nucleon decay matrix element is also discussed.

  19. A new approach to analytic, non-perturbative and gauge-invariant QCD

    SciTech Connect

    Fried, H.M.; Grandou, T.; Sheu, Y.-M.

    2012-11-15

    Following a previous calculation of quark scattering in eikonal approximation, this paper presents a new, analytic and rigorous approach to the calculation of QCD phenomena. In this formulation a basic distinction between the conventional 'idealistic' description of QCD and a more 'realistic' description is brought into focus by a non-perturbative, gauge-invariant evaluation of the Schwinger solution for the QCD generating functional in terms of the exact Fradkin representations of Green's functional G{sub c}(x,y|A) and the vacuum functional L[A]. Because quarks exist asymptotically only in bound states, their transverse coordinates can never be measured with arbitrary precision; the non-perturbative neglect of this statement leads to obstructions that are easily corrected by invoking in the basic Lagrangian a probability amplitude which describes such transverse imprecision. The second result of this non-perturbative analysis is the appearance of a new and simplifying output called 'Effective Locality', in which the interactions between quarks by the exchange of a 'gluon bundle'-which 'bundle' contains an infinite number of gluons, including cubic and quartic gluon interactions-display an exact locality property that reduces the several functional integrals of the formulation down to a set of ordinary integrals. It should be emphasized that 'non-perturbative' here refers to the effective summation of all gluons between a pair of quark lines-which may be the same quark line, as in a self-energy graph-but does not (yet) include a summation over all closed-quark loops which are tied by gluon-bundle exchange to the rest of the 'Bundle Diagram'. As an example of the power of these methods we offer as a first analytic calculation the quark-antiquark binding potential of a pion, and the corresponding three-quark binding potential of a nucleon, obtained in a simple way from relevant eikonal scattering approximations. A second calculation, analytic, non-perturbative and

  20. S U (2 ) gauge field theories, gauge-invariant angular momenta, and a Coulomb theorem: A new viewpoint on the resolution of the nucleon spin crisis

    NASA Astrophysics Data System (ADS)

    Huang, Changyu; Huang, Yong-Chang; Zhou, Bao-Hua

    2015-09-01

    We investigate the inner structure of a general S U (2 ) [naturally including S O (3 )] symmetry system—the fermion-gauge field interaction system—and achieve naturally a set of gauge-invariant spin and orbital angular momentum operators of fermion and gauge fields by Noether's theorem in general field theory. Some new relations concerning non-Abelian field strengths are discovered, e.g., the covariant transverse condition, covariant parallel condition (i.e., non-Abelian divergence, non-Abelian curl), and simplified S U (2 ) Coulomb theorem. And we show that the condition that Chen et al. obtained to construct their gauge-invariant angular momentum operators is a result of some fundamental equations in the general field theory. The results obtained in this paper present a new perspective for looking at the overall structure of the gauge field, and provide a new viewpoint to the final resolution of the nucleon spin crisis in the general field theory. Especially, the achieved theory in this paper can calculate the strong interactions with isospin symmetry and solves the serious problem without gauge-invariant angular momenta in strong interaction systems with isospin symmetry, and then the achieved predictions in the calculations can be exactly measured by particle physics experiments due to their gauge invariant properties.

  1. Discussion About the Magnetic Field Dimensionality, Invariant Axis Condition, and Coulomb Gauge to Solve the Grad-Shafranov Equation

    NASA Astrophysics Data System (ADS)

    González, A. Ojeda; Prestes, A.; Laurindo Sousa, A. Nilson

    2016-08-01

    We discuss the relationship between the Coulomb gauge, the existence of an invariant axis, and the dimensionality (2-D or 2frac {1}{2}-D) of the magnetic field in a mathematical-physical formalism that leads us to the Grad-Shafranov (GS) equation. In the literature, we found that a 2-D magnetic structure is used as a prerequisite to derive the GS equation from the Vlasov equation. However, other consulted works are based on a 2frac {1}{2}-D (two-and-a-half) magnetic structure as a prerequisite to derive the GS equation from the balance of forces between the pressure gradient and the magnetic force, respectively. We replaced the magnetic vector potential on Ampère's equation and used the Coulomb gauge to obtain a system of three Poisson equations, one for each component. We also used the same procedure explained above, but without the Coulomb gauge. Comparing z-component in both equation systems, we concluded that there are two possible solutions. We suggest using a 2frac {1}{2}-D magnetic field configuration instead of a 2-D, when working with kinetic theory or magnetostatic equilibrium to derive the GS equation. We clarified that there is no relationship between the Coulomb gauge and the magnetic field dimensionality. In this problem, the invariant axis condition is imposed, which means that ěc {nabla }\\cdot ěc {A} is independent of z, i.e., ěc {nabla }\\cdot ěc {A} could have any value in which an invariant axis is a sufficient condition to obtain the GS equation.

  2. Chiral quark dynamics and topological charge: The role of the Ramond-Ramond U(1) gauge field in holographic QCD

    NASA Astrophysics Data System (ADS)

    Thacker, H. B.; Xiong, Chi; Kamat, Ajinkya S.

    2011-11-01

    The Witten-Sakai-Sugimoto construction of holographic QCD in terms of D4 color branes and D8 flavor branes in type IIA string theory is used to investigate the role of topological charge in the chiral dynamics of quarks in QCD. The QCD theta term arises from a compactified five-dimensional Chern-Simons term on the D4 branes. This term couples the QCD topological charge to the Ramond-Ramond (RR) U(1) gauge field of type IIA string theory. For large Nc the contribution of instantons (D0 branes) is suppressed, and the nonzero topological susceptibility of pure-glue QCD is attributed to the presence of D6 branes, which constitute magnetic sources of the RR gauge field. The topological charge of QCD is required, by an anomaly inflow argument, to coincide in space-time with the intersection of the D6 branes and the D4 color branes. This clarifies the relation between D6 branes and the coherent, codimension-one topological charge membranes observed in QCD Monte Carlo calculations. Using open-string/closed-string duality, we interpret a quark loop (represented by a D4-D8 open-string loop) in terms of closed-string exchange between color and flavor branes. The role of the RR gauge field in quark-antiquark annihilation processes is discussed. RR exchange in the s-channel generates a 4-quark contact term which produces an η' mass insertion and provides an explanation for the observed spin-parity structure of the Okubo-Zweig-Iizuka rule. The (log⁡DetU)2 form of the U(1) anomaly emerges naturally. RR exchange in the t-channel of the qq¯ scattering amplitude produces a Nambu-Jona-Lasinio interaction which may provide a mechanism for spontaneous breaking of SU(Nf)×SU(Nf).

  3. Spectral properties of the gauge invariant quark Green's function in two-dimensional QCD

    SciTech Connect

    Sazdjian, H.

    2010-06-01

    The gauge invariant quark Green's function with a path-ordered phase factor along a straight line is studied in two-dimensional QCD in the large-N{sub c} limit by means of an exact integrodifferential equation. Its spectral functions are analytically determined. They are infrared finite and lie on the positive real axis of the complex plane of the momentum squared variable, corresponding to momenta in the forward light cone. Their singularities are represented by an infinite number of threshold type branch points with power-law -3/2, starting at positive mass values, characterized by an integer number n and increasing with n. The analytic expression of the Green's function for all momenta is presented. The appearance of strong threshold singularities is suggestive of the fact that quarks could not be observed as asymptotic states.

  4. Nonperturbative renormalization of meson decay constants in quenched QCD for a renormalization group improved gauge action

    SciTech Connect

    Ide, K.; Aoki, S.; Kanaya, K.; Taniguchi, Y.; Burkhalter, R.; Ishikawa, K.-I.; Ishizuka, N.; Iwasaki, Y.; Ukawa, A.; Yoshie, T.; Fukugita, M.; Hashimoto, S.; Kaneko, T.; Kuramashi, Y.; Ishikawa, T.; Lesk, V.; Umeda, T.; Okawa, M.

    2004-10-01

    Renormalization constants (Z-factors ) of vector and axial-vector currents are determined nonperturbatively in quenched QCD for a renormalization group improved gauge action and a tadpole-improved clover quark action using the Schroedinger functional method. Nonperturbative values of Z-factors turn out to be smaller than 1-loop perturbative values by O(15%) at a lattice spacing of a{sup -1}{approx_equal} 1 GeV. The pseudoscalar and vector meson decay constants calculated with the nonperturbative Z-factors show a much better scaling behavior compared to previous results obtained with tadpole-improved one-loop Z-factors. In particular, the nonperturbative Z-factors normalized at infinite physical volume show that the scaling violations of the decay constants are within about 10% up to the lattice spacing a{sup -1}{approx}1 GeV. The continuum estimates obtained from data in the range a{sup -1}{approx} 1-2 GeV agree with those determined from finer lattices (a{sup -1}{approx}2-4 GeV) with the standard action.

  5. Finite-temperature Yang-Mills theory in the Hamiltonian approach in Coulomb gauge from a compactified spatial dimension

    NASA Astrophysics Data System (ADS)

    Heffner, J.; Reinhardt, H.

    2015-04-01

    Yang-Mills theory is studied at finite temperature within the Hamiltonian approach in Coulomb gauge by means of the variational principle using a Gaussian-type Ansatz for the vacuum wave functional. Temperature is introduced by compactifying one spatial dimension. As a consequence the finite-temperature behavior is encoded in the vacuum wave functional calculated on the spatial manifold R2×S1(L ) where L-1 is the temperature. The finite-temperature equations of motion are obtained by minimizing the vacuum energy density to two-loop order. We show analytically that these equations yield the correct zero-temperature limit while at infinite temperature they reduce to the equations of the 2 +1 -dimensional theory in accordance with dimensional reduction. The resulting propagators are compared to those obtained from the grand canonical ensemble where an additional Ansatz for the density matrix is required.

  6. Holographic RG flows and universal structures on the Coulomb branch of supersymmetric large- gauge theory

    NASA Astrophysics Data System (ADS)

    Carlisle, James E.; Johnson, Clifford V.

    2003-07-01

    We report on our results of D3-brane probing a large class of generalised type~IIB supergravity solutions presented very recently in the literature. The structure of the solutions is controlled by a single non-linear differential equation. These solutions correspond to renormalisation group flows from pure supersymmetric gauge theory to an gauge theory with a massive adjoint scalar. The gauge group is with large. After presenting the general result, we focus on one of the new solutions, solving for the specific coordinates needed to display the explicit metric on the moduli space. We obtain an appropriately holomorphic result for the coupling. We look for the singular locus, and interestingly, the final result again manifests itself in terms of a square root branch cut on the complex plane, as previously found for a set of solutions for which the details are very different. This, together with the existence of the single simple non-linear differential equation, is further evidence in support of an earlier suggestion that there is a very simple model --- perhaps a matrix model with relation to the Calogero-Moser integrable system --- underlying this gauge theory physics.

  7. Lattice analysis for the energy scale of QCD phenomena.

    PubMed

    Yamamoto, Arata; Suganuma, Hideo

    2008-12-12

    We formulate a new framework in lattice QCD to study the relevant energy scale of QCD phenomena. By considering the Fourier transformation of link variable, we can investigate the intrinsic energy scale of a physical quantity nonperturbatively. This framework is broadly available for all lattice QCD calculations. We apply this framework for the quark-antiquark potential and meson masses in quenched lattice QCD. The gluonic energy scale relevant for the confinement is found to be less than 1 GeV in the Landau or Coulomb gauge.

  8. Gauge symmetry, chirality and parity effects in four-particle systems: Coulomb's law as a universal function for diatomic molecules.

    PubMed

    Van Hooydonk, G

    2000-11-01

    Following recent work in search for a universal function (Van Hooydonk, Eur. J. Inorg. Chem., (1999), 1617), we test four symmetric +/- a(n)Rn potentials for reproducing molecular potential energy curves (PECs). Classical gauge symmetry for 1/R-potentials results in generic left right asymmetric PECs. A pair of symmetric perturbed Coulomb potentials is quantitatively in accordance with observed PECs. For a bond, a four-particle system, charge inversion (a parity effect, atom chirality) is the key to explain this shape generically. A parity adapted Hamiltonian reduces from ten to two terms and to a soluble Bohr-like formula, a Kratzer (1 - Re/R)2 potential. The result is similar to the combined action of spin and wave function symmetry upon the Hamiltonian in Heitler-London theory. Analytical perturbed Coulomb functions varying with (1 - Re/R) scale attractive and repulsive branches of PECs for 13 bonds H2, HF, LiH, KH, AuH, Li2, LiF, KLi, NaCs, Rb2, RbCs, Cs2 and I2 in a single straight line. The 400 turning points for 13 bonds are reproduced with a deviation of 0.007 A at both branches. For 230 points at the repulsive side, the deviation is 0.003 A. The perturbed electrostatic Coulomb law is a universal molecular function. Ab initio zero molecular parameter functions give PECs of acceptable quality, just using atomic ionisation energies. The function can be used as a model potential for inverting levels and gives a first principle's comparison of short- and long-range interactions, important for the study of cold atoms. Wave-packet dynamics, femto-chemistry applied to the crossing of covalent and ionic curves, can provide evidence for this theory. We anticipate this scale/shape invariant scheme applies to smaller scales in nuclear and high-energy particle physics. For larger gravitational scales (Newton 1/R potentials), problems with super-unification are discussed. Reactions between hydrogen and antihydrogen, feasible in the near future, will probably produce

  9. Infrared Dynamics in vector-like gauge Theories: QCD and beyond

    NASA Astrophysics Data System (ADS)

    Elias, Victor

    2001-11-01

    Padé-approximant methods are used to extract information about leading positive zeros or poles of QCD and SQCD β-functions from the known terms of their perturbative series. For QCD, such methods are seen to corroborate the flavor-threshold behavior obtained via lattice approaches for the occurrence of infrared-stable fixed points. All possible Padé-approximant versions of the known (one- to four-loop) terms of the QCD MS β-function series are consistent with this threshold occurring at or above nf=6. This conclusion continues to be true even if higher-degree Padé-approximants are introduced to accommodate an arbitrary five-loop contribution to the QCD β-function for a given number of flavors. .

  10. Nonperturbative O(a) improvement of Wilson quark action in three-flavor QCD with plaquette gauge action

    SciTech Connect

    Yamada, N.; Hashimoto, S.; Kaneko, T.; Tsutsui, N.; Aoki, S.; Taniguchi, Y.; Fukugita, M.; Ishikawa, K-I.; Okawa, M.; Ishizuka, N.; Iwasaki, Y.; Kanaya, K.; Kuramashi, Y.; Ukawa, A.; Yoshie, T.

    2005-03-01

    We perform a nonperturbative determination of the O(a)-improvement coefficient c{sub SW} for the Wilson quark action in three-flavor QCD with the plaquette gauge action. Numerical simulations are carried out in a range of {beta}=12.0-5.2 on a single lattice size of 8{sup 3}x16 employing the Schroedinger functional setup of lattice QCD. As our main result, we obtain an interpolation formula for c{sub SW} and the critical hopping parameter K{sub c} as a function of the bare coupling. This enables us to remove the O(a) scaling violation from physical observables in future numerical simulation in the wide range of {beta}. Our analysis with a perturbatively modified improvement condition for c{sub SW} suggests that finite volume effects in c{sub SW} are not large on the 8{sup 3}x16 lattice. We investigate N{sub f} dependence of c{sub SW} by additional simulations for N{sub f}=4, 2, and 0 at {beta}=9.6. As a preparatory step for this study, we also determine c{sub SW} in two-flavor QCD at {beta}=5.2. At this {beta}, several groups have carried out large-scale calculations of the hadron spectrum, while no systematic determination of c{sub SW} has been performed.

  11. Continuous Advances in QCD 1996 - Proceedings of the ConfernceE

    NASA Astrophysics Data System (ADS)

    Polikarpov, M. I.

    1996-11-01

    Table of Contents for the full book PDF is as follows: * Foreword * SECTION 1. HEAVY QUARKS * Higher Moments of Heavy Quark Vacuum Polarization * Signatures of Color-Octet Quarkonium Production * Treating the Lifetimes of Charm and Beauty Hadrons with QCD Plus a Bit More! * Hadronic Spectral Moments in Inclusive B and D Decays * Measuring αs(Q2) in τ Decays * On Infrared Cancellations in Inclusive Heavy Particles Decays * Calculation of the B → π Transition Matrix Element in QCD * SECTION 2. HIGH ENERGY SCATTERING AND RENORMALONS * Leading 1/Q Power Corrections in QCD: Universality and KLN Cancellations * Effective Action for High-Energy Scattering in QCD * The Generalized Crewther Relation: The Peculiar Aspects of Analytical Perturbative QCD Calculations * Global QCD Analysis, the Gluon Distribution, αs, and New DIS & Inclusive Jet Data * Resummation of Threshold Corrections in QCD to Power Accuracy: The Drell-Yan Cross Section as a Case Study * SECTION 3. FINITE TEMPERATURE * Lifetime of Quasiparticle Excitations in Hot Gauge Theories * News About Instantons in QCD * The Intrinsic Glue Distribution at Very Small x and High Densities * Interfaces in Hot Gauge Theory * Cool Pions Move at Less Than the Speed of Light * Squeezed Gluons and Gauge Invariant Variational Wave Functional * SECTION 4. LATTICE * Evidence for the Observation of a Glueball * Testing Improved Actions * Perfect Lattice Actions for Quarks and Gluons * Dual Lattice Blockspin Transformation and Monopole Condensation in QCD * Properties of QCD Vacuum from Lattice * Dispersive Theory of Charmonium on the Lattice * SECTION 5. DYNAMICS OF GAUGE FIELDS * Higher Loops and Consistency Conditions in SUSY Gauge Theories * One-Loop QCD Amplitudes from Cutkosky Rules * On the Spectrum of the QCD Dirac Operator * Deep Inelastic Scattering and Light-Cone Wave Functions * Constituent Quark Model Versus Nonperturbative QCD * Phase Transitions in Non-Abelian Coulomb Gases at Large N * Non

  12. A new approach to analytic, non-perturbative, gauge-invariant QCD renormalization is described, with applications to high energy elastic pp-scattering.

    NASA Astrophysics Data System (ADS)

    Fried, H. M.; Tsang, P. H.; Gabellini, Y.; Grandou, T.; Sheu, Y.-M.

    2016-11-01

    A new non-perturbative, gauge-invariant model QCD renormalization is applied to high energy elastic pp-scattering. The differential cross-section deduced from this model displays a diffraction dip that resembles those of experiments. Comparison with ISR and LHC data is currently underway.

  13. String breaking in four dimensional lattice QCD

    SciTech Connect

    Duncan, A.; Eichten, E.; Thacker, H.

    2001-06-01

    Virtual quark pair screening leads to breaking of the string between fundamental representation quarks in QCD. For unquenched four dimensional lattice QCD, this (so far elusive) phenomenon is studied using the recently developed truncated determinant algorithm (TDA). The dynamical configurations were generated on a 650 MHz PC. Quark eigenmodes up to 420 MeV are included exactly in these TDA studies performed at low quark mass on large coarse [but O(a{sup 2}) improved] lattices. A study of Wilson line correlators in Coulomb gauge extracted from an ensemble of 1000 two-flavor dynamical configurations reveals evidence for flattening of the string tension at distances R{approx}>1 fm.

  14. Are the dressed gluon and ghost propagators in the Landau gauge presently determined in the confinement regime of QCD?

    SciTech Connect

    Pennington, M. R.; Wilson, D. J.

    2011-11-01

    The gluon and ghost propagators in Landau gauge QCD are investigated using the Schwinger-Dyson equation approach. Working in Euclidean spacetime, we solve for these propagators using a selection of vertex inputs, initially for the ghost equation alone and then for both propagators simultaneously. The results are shown to be highly sensitive to the choices of vertices. We favor the infrared finite ghost solution from studying the ghost equation alone where we argue for a specific unique solution. In order to solve this simultaneously with the gluon using a dressed-one-loop truncation, we find that a nontrivial full ghost-gluon vertex is required in the vanishing gluon momentum limit. The self-consistent solutions we obtain correspond to having a masslike term in the gluon propagator dressing, in agreement with similar studies supporting the long-held proposal of Cornwall.

  15. An exact, finite, gauge-invariant, non-perturbative approach to QCD renormalization

    SciTech Connect

    Fried, H.M.; Tsang, P.H.; Gabellini, Y.; Grandou, T.; Sheu, Y.-M.

    2015-08-15

    A particular choice of renormalization, within the simplifications provided by the non-perturbative property of Effective Locality, leads to a completely finite, non-perturbative approach to renormalized QCD, in which all correlation functions can, in principle, be defined and calculated. In this Model of renormalization, only the Bundle chain-Graphs of the cluster expansion are non-zero. All Bundle graphs connecting to closed quark loops of whatever complexity, and attached to a single quark line, provided no ‘self-energy’ to that quark line, and hence no effective renormalization. However, the exchange of momentum between one quark line and another, involves only the cluster-expansion’s chain graphs, and yields a set of contributions which can be summed and provide a finite color-charge renormalization that can be incorporated into all other QCD processes. An application to High Energy elastic pp scattering is now underway.

  16. Duality and Other Exotic Gauge Dynamics in Software Broken Supersymmetric QCD

    SciTech Connect

    Peskin, Michael E

    2003-06-11

    We analyze the theory of softly broken supersymmetric QCD. Exotic behavior like spontaneously broken baryon number, massless composite fermions and Seiberg's duality seems to persist also in the presence of (small) soft supersymmetry breaking. We argue that certain, specially tailored, lattice simulations may be able to detect the novel phenomena. Most of the exotic behavior does not survive the decoupling limit of large SUSY breaking parameters.

  17. Matrix elements and diquark correlations in quenched QCD with overlap fermions.

    NASA Astrophysics Data System (ADS)

    Rebbi, Claudio

    2006-12-01

    We present results for BK and selected matrix elements for beyond the standard model interactions obtained in quenched QCD with overlap fermions. We also illustrate results on baryon wave- functions and diquark correlations within baryons in the Coulomb and Landau gauge.

  18. Examining the identity of Yukawa with gauge couplings in supersymmetric QCD at LHC

    SciTech Connect

    Freitas, Ayres; Skands, Peter Z.; Spira, M.; Zerwas, P.M.; /DESY

    2007-03-01

    The identity of the quark-squark-gluino Yukawa coupling with the corresponding quark-quark-gluon QCD coupling in supersymmetric theories can be examined experimentally at the Large Hadron Collider (LHC). Extending earlier investigations of like-sign di-lepton final states, we include jets in the analysis of the minimal supersymmetric standard model, adding squark-gluino and gluino-pair production to squark-pair production. Moreover we expand the method towards model-independent analyses which cover more general scenarios. In all cases, squark decays to light charginos and neutralinos persist to play a dominant role.

  19. Baryonic States in QCD From Gauge/String Duality at Large N{sub C}

    SciTech Connect

    De Teramond, G.

    2004-09-08

    We have computed the baryon spectrum in the framework of {Nu} = 4 super-conformal Yang-Mills theory using AdS/CFT duality. Baryons are included in the theory by adding an open string sector, corresponding to quarks in the fundamental representation of {Nu} = 4. The hadron mass scale is introduced by imposing boundary conditions at the AdS{sub 5} coordinate r{sub 0} = {Lambda}{sub QCD} R{sup 2}, which is the only parameter. The quantum numbers of each baryon, are identified by matching the fall-off of the string wavefunction {Psi}(x,r) at the asymptotic 3+1 boundary to the operator dimension of the lowest three-quark Fock state, subject to appropriate boundary conditions. Higher Fock states are matched quanta to quanta with quantum fluctuations of the bulk geometry about the AdS background. We limit our discussion to massless quarks. The resulting four-dimensional spectrum displays a remarkable resemblance to the physical baryon spectrum of QCD, including the suppression of spin-orbit interactions.

  20. Color superconductivity in the strong-coupling regime of Landau gauge QCD

    SciTech Connect

    Nickel, D.; Wambach, J.; Alkofer, R.

    2006-06-01

    The chirally unbroken and the color-superconducting 2SC and CFL phases are investigated in the chiral limit within a Dyson-Schwinger approach for the quark propagator in QCD. The hierarchy of Green's functions is truncated such that at vanishing density known results for the vacuum and at asymptotically high densities the corresponding weak-coupling expressions are recovered. The anomalous dimensions of the gap functions are analytically calculated. Based on the quark propagator the phase structure is studied, and results for the gap functions, occupation numbers, coherence lengths, and pressure differences are given and compared with the corresponding expressions in the weak-coupling regime. At moderate chemical potentials the quasiparticle pairing gaps are several times larger than the extrapolated weak-coupling results.

  1. Low-energy effective worldsheet theory of a non-Abelian vortex in high-density QCD revisited: A regular gauge construction

    NASA Astrophysics Data System (ADS)

    Chatterjee, Chandrasekhar; Nitta, Muneto

    2017-04-01

    Color symmetry is spontaneously broken in quark matter at high density as a consequence of di-quark condensations with exhibiting color superconductivity. Non-Abelian vortices or color magnetic flux tubes stably exist in the color-flavor locked phase at asymptotically high density. The effective worldsheet theory of a single non-Abelian vortex was previously calculated in the singular gauge to obtain the C P2 model [1,2]. Here, we reconstruct the effective theory in a regular gauge without taking a singular gauge, confirming the previous results in the singular gauge. As a byproduct of our analysis, we find that non-Abelian vortices in high-density QCD do not suffer from any obstruction for the global definition of a symmetry breaking.

  2. Effects of the quark field on the ghost propagator of lattice Landau gauge QCD

    SciTech Connect

    Furui, Sadataka; Nakajima, Hideo

    2006-05-01

    Infrared features of the ghost propagator of color-diagonal and color antisymmetric ghost propagator of quenched SU(2) and quenched SU(3) are compared with those of unquenched Kogut-Susskind fermion SU(3) lattice Landau gauge. We compare (i) the fluctuation of the ghost propagator (ii) the ghost condensate parameter v of the local composite operator (LCO) approach, and (iii) the Binder cumulant of color antisymmetric ghost propagator between quenched and unquenched configurations. The color-diagonal SU(3) ghost dressing function of unquenched configurations has weaker singularity than the quenched configurations. In both cases fluctuations become large in q<0.5 GeV. The ghost condensate parameter v in the ghost propagator of the unquenched MILC{sub c} configuration samples is {approx}0.002-0.04 GeV{sup 2} while that of the SU(2) parallel tempering samples is consistent with 0. The Binder cumulant defined as U(q)=1-(1/3)(<{phi}-vector{sup 4}>/(<{phi}-vector{sup 2}>){sup 2}), where {phi}-vector(q) is the color antisymmetric ghost propagator measured by the sample average of gauge fixed configurations via parallel tempering method, becomes {approx}4/9 in all the momentum region. The Binder cumulant of the color antisymmetric ghost propagator of quenched SU(2) can be explained by the 3D Gaussian distribution, but that of the unquenched MILC{sub c} deviates slightly from that of the eight-dimensional Gaussian distribution. The stronger singularity and large fluctuation in the quenched configuration could be the cause of the deviation of the Kugo-Ojima confinement parameter c from 1, and the presence of ordering in the ghost propagator of unquenched configurations makes it closer to 1.

  3. Gauge cooling for the singular-drift problem in the complex Langevin method — a test in Random Matrix Theory for finite density QCD

    NASA Astrophysics Data System (ADS)

    Nagata, Keitaro; Nishimura, Jun; Shimasaki, Shinji

    2016-07-01

    Recently, the complex Langevin method has been applied successfully to finite density QCD either in the deconfinement phase or in the heavy dense limit with the aid of a new technique called the gauge cooling. In the confinement phase with light quarks, however, convergence to wrong limits occurs due to the singularity in the drift term caused by small eigenvalues of the Dirac operator including the mass term. We propose that this singular-drift problem should also be overcome by the gauge cooling with different criteria for choosing the complexified gauge transformation. The idea is tested in chiral Random Matrix Theory for finite density QCD, where exact results are reproduced at zero temperature with light quarks. It is shown that the gauge cooling indeed changes drastically the eigenvalue distribution of the Dirac operator measured during the Langevin process. Despite its non-holomorphic nature, this eigenvalue distribution has a universal diverging behavior at the origin in the chiral limit due to a generalized Banks-Casher relation as we confirm explicitly.

  4. Behavior of the S parameter in the crossover region between walking and QCD-like regimes of an SU(N) gauge theory

    SciTech Connect

    Kurachi, Masafumi; Shrock, Robert

    2006-09-01

    We consider a vectorial, confining SU(N) gauge theory with a variable number, N{sub f}, of massless fermions transforming according to the fundamental representation. Using the Schwinger-Dyson and Bethe-Salpeter equations, we calculate the S parameter in terms of the current-current correlation functions. We focus on values of N{sub f} such that the theory is in the crossover region between the regimes of walking behavior and QCD-like (nonwalking) behavior. Our calculations indicate that the contribution to S from a given fermion decreases as one moves from the QCD-like to the walking regimes. The implications of this result for technicolor theories are discussed.

  5. Model for QCD ground state with magnetic disorder

    NASA Astrophysics Data System (ADS)

    Szczepaniak, Adam P.; Matevosyan, Hrayr H.

    2010-05-01

    We explore an ansatz for the QCD vacuum in the Coulomb gauge that describes gauge field fluctuations in the presence of a weakly interacting gas of Abelian monopoles. Such magnetic disorder leads to long-range correlations which are manifested through the area law for the Wilson loop. In particular we focus on the role of the residual monopole-monopole interactions in providing the mechanism for suppression of the gluon propagator at low momenta which also leads to low-momentum enhancement in the ghost propagator.

  6. QCD for Postgraduates (1/5)

    ScienceCinema

    None

    2016-07-12

    Modern QCD - Lecture 1 Starting from the QCD Lagrangian we will revisit some basic QCD concepts and derive fundamental properties like gauge invariance and isospin symmetry and will discuss the Feynman rules of the theory. We will then focus on the gauge group of QCD and derive the Casimirs CF and CA and some useful color identities.

  7. High-loop perturbative renormalization constants for Lattice QCD (III): three-loop quark currents for Iwasaki gauge action and Wilson fermions

    NASA Astrophysics Data System (ADS)

    Brambilla, M.; Di Renzo, F.; Hasegawa, M.

    2014-07-01

    This is the third of a series of papers on three-loop computation of renormalization constants for Lattice QCD. Our main points of interest are results for the regularization defined by the Iwasaki gauge action and Wilson fermions. Our results for quark bilinears renormalized according to the RI'-MOM scheme can be compared to non-perturbative results. The latter are available for twisted mass QCD: being defined in the chiral limit, the renormalization constants must be the same. We also address more general problems. In particular, we discuss a few methodological issues connected to summing the perturbative series such as the effectiveness of boosted perturbation theory and the disentanglement of irrelevant and finite-volume contributions. Discussing these issues we consider not only the new results of this paper, but also those for the regularization defined by the tree-level Symanzik improved gauge action and Wilson fermions, which we presented in a recent paper of ours. We finally comment on the extent to which the techniques we put at work in the NSPT context can provide a fresher look into the lattice version of the RI'-MOM scheme.

  8. MS overline -on-shell quark mass relation up to four loops in QCD and a general SU (N ) gauge group

    NASA Astrophysics Data System (ADS)

    Marquard, Peter; Smirnov, Alexander V.; Smirnov, Vladimir A.; Steinhauser, Matthias; Wellmann, David

    2016-10-01

    We compute the relation between heavy quark masses defined in the modified minimal subtraction and the on-shell schemes. Detailed results are presented for all coefficients of the SU (Nc) color factors. The reduction of the four-loop on-shell integrals is performed for a general QCD gauge parameter. Altogether there are about 380 master integrals. Some of them are computed analytically, others with high numerical precision using Mellin-Barnes representations, and the rest numerically with the help of FIESTA. We discuss in detail the precise numerical evaluation of the four-loop master integrals. Updated relations between various short-distance masses and the MS ¯ quark mass to next-to-next-to-next-to-leading order accuracy are provided for the charm, bottom and top quarks. We discuss the dependence on the renormalization and factorization scale.

  9. SO(4) group structure for a motivated QCD Hamiltonian: Analytic and Tamm-Dancoff solutions

    NASA Astrophysics Data System (ADS)

    Yepez-Martinez, Tochtli; Civitarese, Osvaldo; Hess, Peter O.

    2016-08-01

    Starting from the QCD Hamiltonian written in the canonical Coulomb gauge formalism, we developed a mapping onto an SO(4) representation which is suitable for the description of the QCD spectra at low energies. The mapping does not break the flavor symmetry and it preserves the singlet-colorless structure of the states. We present and discuss the structure of integer and half-integer-spin states with masses below 2 GeV. Finally, we extend the formalism in order to include particle-hole-like correlations in building excitations.

  10. Gluon-propagator functional form in the Landau gauge in SU(3) lattice QCD: Yukawa-type gluon propagator and anomalous gluon spectral function

    SciTech Connect

    Iritani, Takumi; Suganuma, Hideo; Iida, Hideaki

    2009-12-01

    We study the gluon propagator D{sub {mu}}{sub {nu}}{sup ab}(x) in the Landau gauge in SU(3) lattice QCD at {beta}=5.7, 5.8, and 6.0 at the quenched level. The effective gluon mass is estimated as 400-600 MeV for r{identical_to}(x{sub {alpha}}x{sub {alpha}}){sup 1/2}=0.5-1.0 fm. Through the functional-form analysis of D{sub {mu}}{sub {nu}}{sup ab}(x) obtained in lattice QCD, we find that the Landau-gauge gluon propagator D{sub {mu}}{sub {mu}}{sup aa}(r) is well described by the Yukawa-type function e{sup -mr}/r with m{approx_equal}600 MeV for r=0.1-1.0 fm in the four-dimensional Euclidean space-time. In the momentum space, the gluon propagator D-tilde{sub {mu}}{sub {mu}}{sup aa}(p{sup 2}) with (p{sup 2}){sup 1/2}=0.5-3 GeV is found to be well approximated with a new-type propagator of (p{sup 2}+m{sup 2}){sup -3/2}, which corresponds to the four-dimensional Yukawa-type propagator. Associated with the Yukawa-type gluon propagator, we derive analytical expressions for the zero-spatial-momentum propagator D{sub 0}(t), the effective mass M{sub eff}(t), and the spectral function {rho}({omega}) of the gluon field. The mass parameter m turns out to be the effective gluon mass in the infrared region of {approx}1 fm. As a remarkable fact, the obtained gluon spectral function {rho}({omega}) is almost negative definite for {omega}>m, except for a positive {delta}-functional peak at {omega}=m.

  11. Interface tension between order-order domains in pure gauge QCD phase interfaces in QCD adn spin models: A video presentation

    NASA Astrophysics Data System (ADS)

    Kärkkäinen, Leo; Rummukainen, Kari

    1991-05-01

    This paper summarizes the contents of two talks presented at the conference. We compute the interface tension αoo of the interface between two ordered domains having different Z(3) values in Nt = 2 lattice SU(3) gauge theory. The interface is created dynamically by a twist along one plane of the lattice. We also study the variation of the order parameter < L> and of thermodynamic quantities across the interface. The formation of the interface and its fluctuations in Monte Carlo time were shown in a video presented at the conference.

  12. Scale of dark QCD

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Schwaller, Pedro

    2014-03-01

    Most of the mass of ordinary matter has its origin from quantum chromodynamics (QCD). A similar strong dynamics, dark QCD, could exist to explain the mass origin of dark matter. Using infrared fixed points of the two gauge couplings, we provide a dynamical mechanism that relates the dark QCD confinement scale to our QCD scale, and hence provides an explanation for comparable dark baryon and proton masses. Together with a mechanism that generates equal amounts of dark baryon and ordinary baryon asymmetries in the early Universe, the similarity of dark matter and ordinary matter energy densities can be naturally explained. For a large class of gauge group representations, the particles charged under both QCD and dark QCD, necessary ingredients for generating the infrared fixed points, are found to have masses at 1-2 TeV, which sets the scale for dark matter direct detection and novel collider signatures involving visible and dark jets.

  13. New insights into properties of large- N holographic thermal QCD at finite gauge coupling at (the non-conformal/next-to) leading order in N

    NASA Astrophysics Data System (ADS)

    Sil, Karunava; Misra, Aalok

    2016-11-01

    It is believed that large- N thermal QCD laboratories like strongly coupled QGP (sQGP) require not only a large `t Hooft coupling but also a finite gauge coupling (Natsuume, String theory and quark-gluon plasma. arXiv:hep-ph/0701201, 2007). Unlike almost all top-down holographic models in the literature, holographic large- N thermal QCD models, based on this assumption, therefore necessarily require addressing this limit from M-theory. This was initiated in Dhuria and Misra (JHEP 1311:001, 2013) which presented a local M-theory uplift of the string theoretic dual of large- N thermal QCD-like theories at finite gauge/string coupling of Mia et al. (Nucl. Phys. B 839:187, arXiv:0902.1540 [hep-th], 2010) (g_s gauge coupling, have been entirely missing in the literature. In this paper we largely address the following two non-trivial issues pertaining to the same. First, up to LO in N (the number of D3-branes), by calculating the temperature dependence of the thermal (and electrical) conductivity and the consequent deviation from the Wiedemann-Franz law, upon comparison with Garg et al. (Phys. Rev. Lett. 103:096402, 2009), we show that, remarkably, the results qualitatively mimic a 1+1-dimensional Luttinger liquid with impurities. Second, by looking at, respectively, the scalar, vector, and tensor modes of metric perturbations and using the prescription of Kovtun and Starinets (Phys. Rev. D 72:086009, arXiv:hep-th/0506184, 2005) for constructing appropriate gauge-invariant perturbations, we obtain the non-conformal corrections to the conformal results (but at finite g_s), respectively, for the speed of sound, the shear mode diffusion constant, and the shear viscosity η (and η /s). The new insight gained is that it turns out that these

  14. Instanton effects in three-dimensional supersymmetric gauge theories with matter

    NASA Astrophysics Data System (ADS)

    Dorey, Nick; Tong, David; Vandoren, Stefan

    1998-04-01

    Using standard field theory techniques we compute perturbative and instanton contributions to the Coulomb branch of three-dimensional supersymmetric QCD with N = 2 and N = 4 supersymmetry and gauge group SU(2). For the N = 4 theory with one massless flavor, we confirm the proposal of Seiberg and Witten that the Coulomb branch is the double-cover of the centered moduli space of two BPS monopoles constructed by Atiyah and Hitchin. Introducing a hypermultiplet mass term, we show that the asymptotic metric on the Coulomb branch coincides with the metric on Dancer's deformation of the monopole moduli space. For the N = 2 theory with Nf flavors, we compute the one-loop corrections to the metric and complex structure on the Coulomb branch. We then determine the superpotential including one-loop effects around the instanton background. These calculations provide an explicit check of several results previously obtained by symmetry and holomorphy arguments.

  15. QCD In Extreme Conditions

    NASA Astrophysics Data System (ADS)

    Wilczek, Frank

    Introduction Symmetry and the Phenomena of QCD Apparent and Actual Symmetries Asymptotic Freedom Confinement Chiral Symmetry Breaking Chiral Anomalies and Instantons High Temperature QCD: Asymptotic Properties Significance of High Temperature QCD Numerical Indications for Quasi-Free Behavior Ideas About Quark-Gluon Plasma Screening Versus Confinement Models of Chiral Symmetry Breaking More Refined Numerical Experiments High-Temperature QCD: Phase Transitions Yoga of Phase Transitions and Order Parameters Application to Glue Theories Application to Chiral Transitions Close Up on Two Flavors A Genuine Critical Point! (?) High-Density QCD: Methods Hopes, Doubts, and Fruition Another Renormalization Group Pairing Theory Taming the Magnetic Singularity High-Density QCD: Color-Flavor Locking and Quark-Hadron Continuity Gauge Symmetry (Non)Breaking Symmetry Accounting Elementary Excitations A Modified Photon Quark-Hadron Continuity Remembrance of Things Past More Quarks Fewer Quarks and Reality

  16. Study for the Pentaquark Potential in SU(3) Lattice QCD

    SciTech Connect

    Okiharu, Fumiko; Suganuma, Hideo; Takahashi, Toru T.

    2005-05-20

    We perform the first study of the static pentaquark (5Q) potential V{sub 5Q} in SU(3) quenched lattice QCD with 16{sup 3}x32 and {beta}=6.0. From the 5Q Wilson loop, V{sub 5Q} is calculated in a gauge-invariant manner, with the smearing method to enhance the ground-state component. V{sub 5Q} is well described by the OGE-plus-multi-Y ansatz: a sum of the one-gluon-exchange (OGE) Coulomb term and the multi-Y-type linear term proportional to the minimal total length of the flux tube linking the five quarks. Comparing with QQ and 3Q potentials, we find a universality of the string tension, {sigma}{sub QQ}{approx_equal}{sigma}{sub 3Q}{approx_equal}{sigma}{sub 5Q}, and the OGE result for Coulomb coefficients.

  17. Coulomb string tension, asymptotic string tension, and the gluon chain

    SciTech Connect

    Greensite, Jeff; Szczepaniak, Adam P.

    2015-02-01

    We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  18. Coulomb string tension, asymptotic string tension, and the gluon chain

    DOE PAGES

    Greensite, Jeff; Szczepaniak, Adam P.

    2015-02-01

    We compute, via numerical simulations, the non-perturbative Coulomb potential and position-space ghost propagator in pure SU(3) gauge theory in Coulomb gauge. We find that that the Coulomb potential scales nicely in accordance with asymptotic freedom, that the Coulomb potential is linear in the infrared, and that the Coulomb string tension is about four times larger than the asymptotic string tension. We explain how it is possible that the asymptotic string tension can be lower than the Coulomb string tension by a factor of four.

  19. Glueball physics in QCD

    NASA Astrophysics Data System (ADS)

    Cho, Y. M.; Pham, X. Y.; Zhang, Pengming; Xie, Ju-Jun; Zou, Li-Ping

    2015-06-01

    The Abelian decomposition of QCD which decomposes the gluons to the color neutral binding gluons and the colored valence gluons shows that QCD can be viewed as the restricted QCD (RCD) made of the binding gluons which has the valence gluons as colored source, and simplifies the QCD dynamics greatly. In particular, it tells that the gauge covariant valence gluons can be treated as the constituents of hadrons, and generalizes the quark model to the quark and valence gluon model. So it provides a comprehensive picture of glueballs and their mixing with quarkoniums, and predicts new hybrid hadrons made of quarks and valence gluons. We discuss how these predictions could be confirmed experimentally. In particular we present a systematic search for the ground state glueballs and their mixing with quarkoniums below 2 GeV in 0++ , 2++, and 0-+ channels within the framework of QCD, and predict the relative branching ratios of the radiative decay of ψ to the physical states.

  20. Deconfinement on {{R}}^2× {S}_L^1× {S}_{β}^1 for all gauge groups and duality to double Coulomb gas

    NASA Astrophysics Data System (ADS)

    Teeple, Brett

    2016-04-01

    I study finite-temperature {N}=1 super Yang-Mills for any gauge group G = A N , B N , C N , D N , E 6,7,8, F 4, G 2, compactified from four dimensions on a torus, {{R}}^2× {S}_L^1× {S}_{β}^1 . I examine in particular the low temperature regime L ≪ β = 1/ T, where L is the length of the spatial circle with periodic boundary conditions and with anti-periodic boundary conditions for the adjoint gauginos along the thermal cycle S β 1 . For small such L we are in a regime were semiclassical calculations can be performed and a transition occurs at T c much smaller than 1/ NL. The transition is mediated by the competition between non-perturbative objects including `exotic' topological molecules: neutral and magnetic bions composed of BPS and KK monopole constituents, with r = rank( G) different charges in the co-root lattice of the gauge group G, and the perturbative electrically charged W-bosons (along with their wino superpartners).

  1. Baryonic flux in quenched and two-flavor dynamical QCD after Abelian projection

    SciTech Connect

    Bornyakov, V.G.; Ichie, H.; Mori, Y.; Suzuki, T.; Pleiter, D.; Schierholz, G.; Streuer, T.; Stueben, H.

    2004-09-01

    We study the distribution of color electric flux of the three-quark system in quenched and full QCD (with N{sub f}=2 flavors of dynamical quarks) at zero and finite temperature. To reduce ultraviolet fluctuations, the calculations are done in the Abelian projected theory fixed to the maximally Abelian gauge. In the confined phase we find clear evidence for a Y-shape flux tube surrounded and formed by the solenoidal monopole current, in accordance with the dual superconductor picture of confinement. In the deconfined, high temperature phase monopoles cease to condense, and the distribution of the color electric field becomes Coulomb-like.

  2. Coulomb Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

    Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

  3. Coulomb Damping

    ERIC Educational Resources Information Center

    Fay, Temple H.

    2012-01-01

    Viscous damping is commonly discussed in beginning differential equations and physics texts but dry friction or Coulomb friction is not despite dry friction being encountered in many physical applications. One reason for avoiding this topic is that the equations involve a jump discontinuity in the damping term. In this article, we adopt an energy…

  4. Lattice QCD

    SciTech Connect

    Bornyakov, V.G.

    2005-06-01

    Possibilities that are provided by a lattice regularization of QCD for studying nonperturbative properties of QCD are discussed. A review of some recent results obtained from computer calculations in lattice QCD is given. In particular, the results for the QCD vacuum structure, the hadron mass spectrum, and the strong coupling constant are considered.

  5. Static quark-antiquark potential in the quark-gluon plasma from lattice QCD.

    PubMed

    Burnier, Yannis; Kaczmarek, Olaf; Rothkopf, Alexander

    2015-02-27

    We present a state-of-the-art determination of the complex valued static quark-antiquark potential at phenomenologically relevant temperatures around the deconfinement phase transition. Its values are obtained from nonperturbative lattice QCD simulations using spectral functions extracted via a novel Bayesian inference prescription. We find that the real part, both in a gluonic medium, as well as in realistic QCD with light u, d, and s quarks, lies close to the color singlet free energies in Coulomb gauge and shows Debye screening above the (pseudo)critical temperature T_{c}. The imaginary part is estimated in the gluonic medium, where we find that it is of the same order of magnitude as in hard-thermal loop resummed perturbation theory in the deconfined phase.

  6. Two-loop master integrals for the leading QCD corrections to the Higgs coupling to a W pair and to the triple gauge couplings ZW W and γ∗ W W

    NASA Astrophysics Data System (ADS)

    Di Vita, Stefano; Mastrolia, Pierpaolo; Primo, Amedeo; Schubert, Ulrich

    2017-04-01

    We compute the two-loop master integrals required for the leading QCD corrections to the interaction vertex of a massive neutral boson X 0, e.g. H, Z or γ∗, with a pair of W bosons, mediated by a SU(2) L quark doublet composed of one massive and one massless flavor. All the external legs are allowed to have arbitrary invariant masses. The Magnus exponential is employed to identify a set of master integrals that, around d = 4 space-time dimensions, obey a canonical system of differential equations. The canonical master integrals are given as a Taylor series in ɛ = (4 - d) /2, up to order four, with coefficients written as combination of Goncharov polylogarithms, respectively up to weight four. In the context of the Standard Model, our results are relevant for the mixed EW-QCD corrections to the Higgs decay to a W pair, as well as to the production channels obtained by crossing, and to the triple gauge boson vertices ZWW and γ∗ WW.

  7. Coulomb flux tube on the lattice

    NASA Astrophysics Data System (ADS)

    Chung, Kristian; Greensite, Jeff

    2017-08-01

    In Coulomb gauge a longitudinal electric field is generated instantaneously with the creation of a static quark-antiquark pair. The field due to the quarks is a sum of two contributions, one from the quark and one from the antiquark, and there is no obvious reason that this sum should fall off exponentially with distance from the sources. We show here, however, from numerical simulations in pure SU(2) lattice gauge theory, that the color Coulomb electric field does in fact fall off exponentially with transverse distance away from a line joining static quark-antiquark sources, indicating the existence of a color Coulomb flux tube, and the absence of long-range Coulomb dipole fields.

  8. A new approach to radial and axial gauges

    NASA Astrophysics Data System (ADS)

    Weigert, Heribert; Heinz, Ulrich

    1992-03-01

    We develop a new path integral formulation of QCD in radial and axial gauges. This formalism yields free propagators which are free of gauge poles. We find that radial gauges are ghost free. In axial gauges ghosts cannot generally be excluded from the formalism due to the need to fix the residual gauge freedom.

  9. Lattice gauge theories

    NASA Astrophysics Data System (ADS)

    Weisz, Peter; Majumdar, Pushan

    2012-03-01

    Lattice gauge theory is a formulation of quantum field theory with gauge symmetries on a space-time lattice. This formulation is particularly suitable for describing hadronic phenomena. In this article we review the present status of lattice QCD. We outline some of the computational methods, discuss some phenomenological applications and a variety of non-perturbative topics. The list of references is severely incomplete, the ones we have included are text books or reviews and a few subjectively selected papers. Kronfeld and Quigg (2010) supply a reasonably comprehensive set of QCD references. We apologize for the fact that have not covered many important topics such as QCD at finite density and heavy quark effective theory adequately, and mention some of them only in the last section "In Brief". These topics should be considered in further Scholarpedia articles.

  10. Lattice QCD and High Baryon Density State

    SciTech Connect

    Nagata, Keitaro; Nakamura, Atsushi; Motoki, Shinji; Nakagawa, Yoshiyuki; Saito, Takuya

    2011-10-21

    We report our recent studies on the finite density QCD obtained from lattice QCD simulation with clover-improved Wilson fermions of two flavor and RG-improved gauge action. We approach the subject from two paths, i.e., the imaginary and chemical potentials.

  11. QCD at nonzero chemical potential: Recent progress on the lattice

    SciTech Connect

    Aarts, Gert; Jäger, Benjamin; Attanasio, Felipe; Seiler, Erhard; Sexty, Dénes; Stamatescu, Ion-Olimpiu

    2016-01-22

    We summarise recent progress in simulating QCD at nonzero baryon density using complex Langevin dynamics. After a brief outline of the main idea, we discuss gauge cooling as a means to control the evolution. Subsequently we present a status report for heavy dense QCD and its phase structure, full QCD with staggered quarks, and full QCD with Wilson quarks, both directly and using the hopping parameter expansion to all orders.

  12. Some comments on unitarity gauge

    NASA Astrophysics Data System (ADS)

    Lopez-Osorio, M. A.; Martinez-Pascual, E.; Toscano, J. J.

    2004-04-01

    A pedagogical discussion on the unitarity gauge within the context of Hamiltonian path integral formalism is presented. A model based on the group O(N), spontaneously broken down to the subgroup O(N - 1), is used to illustrate the main aspects of this gauge-fixing procedure. Among the issues, discussed with some extent, are: (1) the structure of model's constraints following the Dirac's method, (2) the gauge-fixing procedure, using the unitarity gauge for the massive gauge fields and the Coulomb one for the massless gauge fields, (3) the absence of BRST symmetry in this gauge-fixing procedure and its implications on the renormalizability of the theory, and (4) the static role of the ghost and anti-ghost fields associated with the massive gauge fields and how their contributions can be eliminated by using the dimensional regularization scheme.

  13. Induced QCD I: theory

    NASA Astrophysics Data System (ADS)

    Brandt, Bastian B.; Lohmayer, Robert; Wettig, Tilo

    2016-11-01

    We explore an alternative discretization of continuum SU( N c ) Yang-Mills theory on a Euclidean spacetime lattice, originally introduced by Budzcies and Zirnbauer. In this discretization the self-interactions of the gauge field are induced by a path integral over N b auxiliary boson fields, which are coupled linearly to the gauge field. The main progress compared to earlier approaches is that N b can be as small as N c . In the present paper we (i) extend the proof that the continuum limit of the new discretization reproduces Yang-Mills theory in two dimensions from gauge group U( N c ) to SU( N c ), (ii) derive refined bounds on N b for non-integer values, and (iii) perform a perturbative calculation to match the bare parameter of the induced gauge theory to the standard lattice coupling. In follow-up papers we will present numerical evidence in support of the conjecture that the induced gauge theory reproduces Yang-Mills theory also in three and four dimensions, and explore the possibility to integrate out the gauge fields to arrive at a dual formulation of lattice QCD.

  14. Novel QCD Phenomena

    SciTech Connect

    Brodsky, Stanley J.; /SLAC

    2007-07-06

    I discuss a number of novel topics in QCD, including the use of the AdS/CFT correspondence between Anti-de Sitter space and conformal gauge theories to obtain an analytically tractable approximation to QCD in the regime where the QCD coupling is large and constant. In particular, there is an exact correspondence between the fifth-dimension coordinate z of AdS space and a specific impact variable {zeta} which measures the separation of the quark constituents within the hadron in ordinary space-time. This connection allows one to compute the analytic form of the frame-independent light-front wavefunctions of mesons and baryons, the fundamental entities which encode hadron properties and allow the computation of exclusive scattering amplitudes. I also discuss a number of novel phenomenological features of QCD. Initial- and final-state interactions from gluon-exchange, normally neglected in the parton model, have a profound effect in QCD hard-scattering reactions, leading to leading-twist single-spin asymmetries, diffractive deep inelastic scattering, diffractive hard hadronic reactions, the breakdown of the Lam Tung relation in Drell-Yan reactions, and nuclear shadowing and non-universal antishadowing--leading-twist physics not incorporated in the light-front wavefunctions of the target computed in isolation. I also discuss tests of hidden color in nuclear wavefunctions, the use of diffraction to materialize the Fock states of a hadronic projectile and test QCD color transparency, and anomalous heavy quark effects. The presence of direct higher-twist processes where a proton is produced in the hard subprocess can explain the large proton-to-pion ratio seen in high centrality heavy ion collisions.

  15. Interquark Potential with Finite Quark Mass from Lattice QCD

    SciTech Connect

    Kawanai, Taichi; Sasaki, Shoichi

    2011-08-26

    We present an investigation of the interquark potential determined from the qq Bethe-Salpeter (BS) amplitude for heavy quarkonia in lattice QCD. The qq potential at finite quark mass m{sub q} can be calculated from the equal-time and Coulomb gauge BS amplitude through the effective Schroedinger equation. The definition of the potential itself requires information about a kinetic mass of the quark. We then propose a self-consistent determination of the quark kinetic mass on the same footing. To verify the proposed method, we perform quenched lattice QCD simulations with a relativistic heavy-quark action at a lattice cutoff of 1/a{approx_equal}2.1 GeV in a range 1.0{<=}m{sub q}{<=}3.6 GeV. Our numerical results show that the qq potential in the m{sub q}{yields}{infinity} limit is fairly consistent with the conventional one obtained from Wilson loops. The quark-mass dependence of the qq potential and the spin-spin potential are also examined.

  16. Interquark potential with finite quark mass from lattice QCD.

    PubMed

    Kawanai, Taichi; Sasaki, Shoichi

    2011-08-26

    We present an investigation of the interquark potential determined from the q ̄q Bethe-Salpeter (BS) amplitude for heavy quarkonia in lattice QCD. The q ̄q potential at finite quark mass m(q) can be calculated from the equal-time and Coulomb gauge BS amplitude through the effective Schrödinger equation. The definition of the potential itself requires information about a kinetic mass of the quark. We then propose a self-consistent determination of the quark kinetic mass on the same footing. To verify the proposed method, we perform quenched lattice QCD simulations with a relativistic heavy-quark action at a lattice cutoff of 1/a≈2.1  GeV in a range 1.0≤m(q)≤3.6 GeV. Our numerical results show that the q ̄q potential in the m(q)→∞ limit is fairly consistent with the conventional one obtained from Wilson loops. The quark-mass dependence of the q ̄q potential and the spin-spin potential are also examined. © 2011 American Physical Society

  17. Relevant energy scale of color confinement from lattice QCD

    SciTech Connect

    Yamamoto, Arata; Suganuma, Hideo

    2009-03-01

    We propose a new lattice framework to extract the relevant gluonic energy scale of QCD phenomena which is based on a 'cut' on link variables in momentum space. This framework is expected to be broadly applicable to all lattice QCD calculations. Using this framework, we quantitatively determine the relevant energy scale of color confinement, through the analyses of the quark-antiquark potential and meson masses. The relevant energy scale of color confinement is found to be below 1.5 GeV in the Landau gauge. In fact, the string tension is almost unchanged even after cutting off the high-momentum gluon component above 1.5 GeV. When the relevant low-energy region is cut, the quark-antiquark potential is approximately reduced to a Coulomb-like potential, and each meson becomes a quasifree quark pair. As an analytical model calculation, we also investigate the dependence of the Richardson potential on the cut, and find the consistent behavior with the lattice result.

  18. QCD as a Theory of Hadrons

    NASA Astrophysics Data System (ADS)

    Narison, Stephan

    2007-07-01

    About Stephan Narison; Outline of the book; Preface; Acknowledgements; Part I. General Introduction: 1. A short flash on particle physics; 2. The pre-QCD era; 3. The QCD story; 4. Field theory ingredients; Part II. QCD Gauge Theory: 5. Lagrangian and gauge invariance; 6. Quantization using path integral; 7. QCD and its global invariance; Part III. MS scheme for QCD and QED: Introduction; 8. Dimensional regularization; 9. The MS renormalization scheme; 10. Renormalization of operators using the background field method; 11. The renormalization group; 12. Other renormalization schemes; 13. MS scheme for QED; 14. High-precision low-energy QED tests; Part IV. Deep Inelastic Scattering at Hadron Colliders: 15. OPE for deep inelastic scattering; 16. Unpolarized lepton-hadron scattering; 17. The Altarelli-Parisi equation; 18. More on unpolarized deep inelastic scatterings; 19. Polarized deep-inelastic processes; 20. Drell-Yan process; 21. One 'prompt photon' inclusive production; Part V. Hard Processes in e+e- Collisions: Introduction; 22. One hadron inclusive production; 23. gg scatterings and the 'spin' of the photon; 24. QCD jets; 25. Total inclusive hadron productions; Part VI. Summary of QCD Tests and as Measurements; Part VII. Power Corrections in QCD: 26. Introduction; 27. The SVZ expansion; 28. Technologies for evaluating Wilson coefficients; 29. Renormalons; 30. Beyond the SVZ expansion; Part VIII. QCD Two-Point Functions: 31. References guide to original works; 32. (Pseudo)scalar correlators; 33. (Axial-)vector two-point functions; 34. Tensor-quark correlator; 35. Baryonic correlators; 36. Four-quark correlators; 37. Gluonia correlators; 38. Hybrid correlators; 39. Correlators in x-space; Part IX. QCD Non-Perturbative Methods: 40. Introduction; 41. Lattice gauge theory; 42. Chiral perturbation theory; 43. Models of the QCD effective action; 44. Heavy quark effective theory; 45. Potential approaches to quarkonia; 46. On monopole and confinement; Part X. QCD

  19. QCD as a Theory of Hadrons

    NASA Astrophysics Data System (ADS)

    Narison, Stephan

    2004-05-01

    About Stephan Narison; Outline of the book; Preface; Acknowledgements; Part I. General Introduction: 1. A short flash on particle physics; 2. The pre-QCD era; 3. The QCD story; 4. Field theory ingredients; Part II. QCD Gauge Theory: 5. Lagrangian and gauge invariance; 6. Quantization using path integral; 7. QCD and its global invariance; Part III. MS scheme for QCD and QED: Introduction; 8. Dimensional regularization; 9. The MS renormalization scheme; 10. Renormalization of operators using the background field method; 11. The renormalization group; 12. Other renormalization schemes; 13. MS scheme for QED; 14. High-precision low-energy QED tests; Part IV. Deep Inelastic Scattering at Hadron Colliders: 15. OPE for deep inelastic scattering; 16. Unpolarized lepton-hadron scattering; 17. The Altarelli-Parisi equation; 18. More on unpolarized deep inelastic scatterings; 19. Polarized deep-inelastic processes; 20. Drell-Yan process; 21. One 'prompt photon' inclusive production; Part V. Hard Processes in e+e- Collisions: Introduction; 22. One hadron inclusive production; 23. gg scatterings and the 'spin' of the photon; 24. QCD jets; 25. Total inclusive hadron productions; Part VI. Summary of QCD Tests and as Measurements; Part VII. Power Corrections in QCD: 26. Introduction; 27. The SVZ expansion; 28. Technologies for evaluating Wilson coefficients; 29. Renormalons; 30. Beyond the SVZ expansion; Part VIII. QCD Two-Point Functions: 31. References guide to original works; 32. (Pseudo)scalar correlators; 33. (Axial-)vector two-point functions; 34. Tensor-quark correlator; 35. Baryonic correlators; 36. Four-quark correlators; 37. Gluonia correlators; 38. Hybrid correlators; 39. Correlators in x-space; Part IX. QCD Non-Perturbative Methods: 40. Introduction; 41. Lattice gauge theory; 42. Chiral perturbation theory; 43. Models of the QCD effective action; 44. Heavy quark effective theory; 45. Potential approaches to quarkonia; 46. On monopole and confinement; Part X. QCD

  20. Groupthink and the Blunder of the Gauges

    DTIC Science & Technology

    2011-12-01

    uncritical acceptance of this concept, all textbooks (until very recently) have attributed the concept to H.A. Lorentz rather than its rightful...author, L. Lorenz [1]. The first two editions of Jackson’s “Electrodynamics”, for example, attribute this gauge to H.A. Lorentz . This error is...hidden gauge I =0 and the conflicting Coulomb gauge . One cannot select conflicting gauge choices without violating the laws of physics. 8

  1. Variable flavor number parton distributions and weak gauge and Higgs boson production at hadron colliders at next-to-next-to-leading order of QCD

    SciTech Connect

    Jimenez-Delgado, P.; Reya, E.

    2009-12-01

    Based on our recent next-to-next-to-leading order (NNLO) dynamical parton distributions as obtained in the 'fixed flavor number scheme', we generate radiatively parton distributions in the 'variable flavor number scheme' where the heavy-quark flavors (c,b,t) also become massless partons within the nucleon. Only within this latter factorization scheme are NNLO calculations feasible at present, since the required partonic subprocesses are only available in the approximation of massless initial-state partons. The NNLO predictions for gauge boson production are typically larger (by more than 1{sigma}) than the next-to-leading order (NLO) ones, and rates at LHC energies can be predicted with an accuracy of about 5%, whereas at Tevatron they are more than 2{sigma} above the NLO ones. The NNLO predictions for standard model Higgs-boson production via the dominant gluon fusion process have a total (parton distribution function and scale) uncertainty of about 10% at LHC which almost doubles at the lower Tevatron energies; they are typically about 20% larger than the ones at NLO but the total uncertainty bands overlap.

  2. The QCD running coupling

    DOE PAGES

    Deur, Alexandre; Brodsky, Stanley J.; de Téramond, Guy F.

    2016-05-09

    Here, we review present knowledge onmore » $$\\alpha_{s}$$, the Quantum Chromodynamics (QCD) running coupling. The dependence of $$\\alpha_s(Q^2)$$ on momentum transfer $Q$ encodes the underlying dynamics of hadron physics --from color confinement in the infrared domain to asymptotic freedom at short distances. We will survey our present theoretical and empirical knowledge of $$\\alpha_s(Q^2)$$, including constraints at high $Q^2$ predicted by perturbative QCD, and constraints at small $Q^2$ based on models of nonperturbative dynamics. In the first, introductory, part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain. In the second, more technical, part of the review, we discuss $$\\alpha_s(Q^2)$$ in the high momentum transfer domain of QCD. We review how $$\\alpha_s$$ is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as `` Commensurate Scale Relations" which connect the various definitions of the QCD coupling without renormalization scale ambiguity. We also report recent important experimental measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the ``Principle of Maximum Conformality" which enhances QCD's predictive power by removing the dependence of the predictions for physical observables on the choice of the gauge and renormalization scheme. In last part of the review, we discuss $$\\alpha_s(Q^2)$$ in the low momentum transfer domain, where there has been no consensus on how to define $$\\alpha_s(Q^2)$$ or its analytic behavior. We will discuss the various approaches used for low energy calculations. Among them, we will discuss the light-front holographic approach to QCD in the strongly coupled

  3. The QCD running coupling

    SciTech Connect

    Deur, Alexandre; Brodsky, Stanley J.; de Téramond, Guy F.

    2016-05-09

    Here, we review present knowledge on $\\alpha_{s}$, the Quantum Chromodynamics (QCD) running coupling. The dependence of $\\alpha_s(Q^2)$ on momentum transfer $Q$ encodes the underlying dynamics of hadron physics --from color confinement in the infrared domain to asymptotic freedom at short distances. We will survey our present theoretical and empirical knowledge of $\\alpha_s(Q^2)$, including constraints at high $Q^2$ predicted by perturbative QCD, and constraints at small $Q^2$ based on models of nonperturbative dynamics. In the first, introductory, part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain. In the second, more technical, part of the review, we discuss $\\alpha_s(Q^2)$ in the high momentum transfer domain of QCD. We review how $\\alpha_s$ is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as `` Commensurate Scale Relations" which connect the various definitions of the QCD coupling without renormalization scale ambiguity. We also report recent important experimental measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the ``Principle of Maximum Conformality" which enhances QCD's predictive power by removing the dependence of the predictions for physical observables on the choice of the gauge and renormalization scheme. In last part of the review, we discuss $\\alpha_s(Q^2)$ in the low momentum transfer domain, where there has been no consensus on how to define $\\alpha_s(Q^2)$ or its analytic behavior. We will discuss the various approaches used for low energy calculations. Among them, we will discuss the light-front holographic approach to QCD in the strongly coupled regime and its prediction

  4. The QCD running coupling

    SciTech Connect

    Deur, Alexandre; Brodsky, Stanley J.; de Téramond, Guy F.

    2016-05-09

    Here, we review present knowledge on $\\alpha_{s}$, the Quantum Chromodynamics (QCD) running coupling. The dependence of $\\alpha_s(Q^2)$ on momentum transfer $Q$ encodes the underlying dynamics of hadron physics --from color confinement in the infrared domain to asymptotic freedom at short distances. We will survey our present theoretical and empirical knowledge of $\\alpha_s(Q^2)$, including constraints at high $Q^2$ predicted by perturbative QCD, and constraints at small $Q^2$ based on models of nonperturbative dynamics. In the first, introductory, part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain. In the second, more technical, part of the review, we discuss $\\alpha_s(Q^2)$ in the high momentum transfer domain of QCD. We review how $\\alpha_s$ is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as `` Commensurate Scale Relations" which connect the various definitions of the QCD coupling without renormalization scale ambiguity. We also report recent important experimental measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the ``Principle of Maximum Conformality" which enhances QCD's predictive power by removing the dependence of the predictions for physical observables on the choice of the gauge and renormalization scheme. In last part of the review, we discuss $\\alpha_s(Q^2)$ in the low momentum transfer domain, where there has been no consensus on how to define $\\alpha_s(Q^2)$ or its analytic behavior. We will discuss the various approaches used for low energy calculations. Among them, we will discuss the light-front holographic approach to QCD in the strongly coupled regime and its prediction

  5. Quenched hadron spectrum of QCD

    SciTech Connect

    Kim, Seyong.

    1992-12-01

    We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32[sup 3] [times] 64 lattice volume at [beta] = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the [triangle] masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.

  6. Quenched hadron spectrum of QCD

    SciTech Connect

    Kim, Seyong

    1992-12-01

    We calculate hadron spectrum of quantum chromodynamics without dynamical fermions on a 32{sup 3} {times} 64 lattice volume at {beta} = 6.5. Using two different wall sources of staggered fermion whose mass is 0.01, 0.005 and 0.0025 under the background gauge configurations, we extract local light hadron masses and the {triangle} masses and compare these hadron masses with those from experiments. The numerical simulation is executed on the Intel Touchstone Delta computer. We employ multihit metropolis algorithm with over-relaxation method steps to update gauge field configuration and gauge field configuration are collected at every 1000 sweeps. After the gauge field configuration is fixed to Coulomb gauge, the conjugate gradient method is used for Dirac matrix inversion.

  7. QCD, with strings attached

    NASA Astrophysics Data System (ADS)

    Güijosa, Alberto

    2016-10-01

    In the nearly 20 years that have elapsed since its discovery, the gauge-gravity correspondence has become established as an efficient tool to explore the physics of a large class of strongly-coupled field theories. A brief overview is given here of its formulation and a few of its applications, emphasizing attempts to emulate aspects of the strong-coupling regime of quantum chromodynamics (QCD). To the extent possible, the presentation is self-contained, and does not presuppose knowledge of string theory.

  8. Reliable semiclassical computations in QCD

    NASA Astrophysics Data System (ADS)

    Dine, Michael; Festuccia, Guido; Pack, Lawrence; Wu, Weitao

    2010-09-01

    We revisit the question of whether or not one can perform reliable semiclassical QCD computations at zero temperature. We study correlation functions with no perturbative contributions, and organize the problem by means of the operator product expansion, establishing a precise criterion for the validity of a semiclassical calculation. For Nf>N, a systematic computation is possible; for NfQCD lattice gauge theory computations in the chiral limit.

  9. Glue Spin and Helicity in the Proton from Lattice QCD

    NASA Astrophysics Data System (ADS)

    Yang, Yi-Bo; Sufian, Raza Sabbir; Alexandru, Andrei; Draper, Terrence; Glatzmaier, Michael J.; Liu, Keh-Fei; Zhao, Yong; χ QCD Collaboration

    2017-03-01

    We report the first lattice QCD calculation of the glue spin in the nucleon. The lattice calculation is carried out with valence overlap fermions on 2 +1 flavor domain-wall fermion gauge configurations on four lattice spacings and four volumes including an ensemble with physical values for the quark masses. The glue spin SG in the Coulomb gauge in the modified minimal subtraction (MS ¯ ) scheme is obtained with one-loop perturbative matching. We find the results fairly insensitive to lattice spacing and quark masses. We also find that the proton momentum dependence of SG in the range 0 ≤|p → |<1.5 GeV is very mild, and we determine it in the large-momentum limit to be SG=0.251 (47 )(16 ) at the physical pion mass in the MS ¯ scheme at μ2=10 GeV2 . If the matching procedure in large-momentum effective theory is neglected, SG is equal to the glue helicity measured in high-energy scattering experiments.

  10. A Study of the H-dibaryon in Holographic QCD

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kohei; Nakagawa, Yuya; Suganuma, Hideo

    We study the H-dibaryon (uuddss) in holographic QCD for the first time. Holographic QCD is derived from a QCD-equivalent D-brane system (S1-compactified D4/D8/overline{D8}) in the superstring theory via the gauge/gravity correspondence. In holographic QCD, all baryons appear as topological chiral solitons of Nambu-Goldstone bosons and (axial) vector mesons. In this framework, the H-dibaryon can be described as an SO(3)-type hedgehog state. We present the formalism of the H-dibaryon in holographic QCD, and perform the calculation to investigate its properties in the chiral limit.

  11. Lattice QCD and the Jefferson Laboratory Program

    SciTech Connect

    Jozef Dudek, Robert Edwards, David Richards, Konstantinos Orginos

    2011-06-01

    Lattice gauge theory provides our only means of performing \\textit{ab initio} calculations in the non-perturbative regime. It has thus become an increasing important component of the Jefferson Laboratory physics program. In this paper, we describe the contributions of lattice QCD to our understanding of hadronic and nuclear physics, focusing on the structure of hadrons, the calculation of the spectrum and properties of resonances, and finally on deriving an understanding of the QCD origin of nuclear forces.

  12. Holographic QCD for H-dibaryon (uuddss)

    NASA Astrophysics Data System (ADS)

    Suganuma, Hideo; Matsumoto, Kohei

    2017-03-01

    The H-dibaryon (uuddss) is studied in holographic QCD for the first time. In holographic QCD, four-dimensional QCD, i.e., SU(Nc) gauge theory with chiral quarks, can be formulated with S1-compactified D4/D8/\\overline {{{D8}}} -brane system. In holographic QCD with large (Nc, all the baryons appear as topological chiral solitons of Nambu-Goldstone bosons and (axial) vector mesons, and the H-dibaryon can be described as an SO(3)-type topological soliton with B = 2. We derive the low-energy effective theory to describe the H-dibaryon in holographic QCD. The H-dibaryon mass is found to be twice of the B = 1 hedgehog-baryon mass, MH ≃ 2.00MB=1HH, and is estimated about 1.7GeV, which is smaller than mass of two nucleons (flavor-octet baryons), in the chiral limit.

  13. QCD mechanisms for heavy particle production

    SciTech Connect

    Brodsky, S.J.

    1985-09-01

    For very large pair mass, the production of heavy quarks and supersymmetric particles is expected to be governed by ACD fusion subprocesses. At lower mass scales other QCD mechanisms such as prebinding distortion and intrinsic heavy particle Fock states can become important, possibly accounting for the anomalies observed for charm hadroproduction. We emphasize the importance of final-state Coulomb interactions at low relative velocity in QCD and predict the existence of heavy narrow four quark resonances (c c-bar u u-bar) and (cc c-bar c-bar) in ..gamma gamma.. reactions. Coherent QCD contributions are discussed as a contribution to the non-additivity of nuclear structure functions and heavy particle production cross sections. We also predict a new type of amplitude zero for exclusive heavy meson pair production which follows from the tree-graph structure of QCD. 35 refs., 8 figs., 1 tab.

  14. The QCD vacuum, hadrons and superdense matter

    SciTech Connect

    Shuryak, E.

    1986-01-01

    This is probably the only textbook available that gathers QCD, many-body theory and phase transitions in one volume. The presentation is pedagogical and readable. Contents: The QCD Vacuum: Introduction; QCD on the Lattice Topological Effects in Gauges Theories. Correlation Functions and Microscopic Excitations: Introduction; Operator Product Expansion; The Sum Rules beyond OPE; Nonpower Contributions to Correlators and Instantons; Hadronic Spectroscopy on the Lattice. Dense Matter: Hadronic Matter; Asymptotically Dense Quark-Gluon Plasma; Instantons in Matter; Lattice Calculations at Finite Temperature; Phase Transitions; Macroscopic Excitations and Experiments: General Properties of High Energy Collisions; ''Barometers'', ''Thermometers'', Interferometric ''Microscope''; Experimental Perspectives.

  15. QCD Phase Transitions, Volume 15

    SciTech Connect

    Schaefer, T.; Shuryak, E.

    1999-03-20

    The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.

  16. Gauged Q-balls

    NASA Technical Reports Server (NTRS)

    Lee, Kimyeong; Stein-Schabes, Jaime A.; Watkins, Richard; Widrow, Lawrence M.

    1988-01-01

    Classical non-topological soliton configurations are considered within the theory of a complex scalar field with a gauged U symmetry. Their existence and stability against dispersion are demonstrated and some of their properties are investigated analytically and numerically. The soliton configuration is such that inside the soliton the local U symmetry is broken, the gauge field becomes massive and for a range of values of the coupling constants the soliton becomes a superconductor pushing the charge to the surface. Furthermore, because of the repulsive Coulomb force, there is a maximum size for these objects, making impossible the existence of Q-matter in bulk form. Also briefly discussed are solitons with fermions in a U gauge theory.

  17. Mechanisms of chiral symmetry breaking in QCD: A lattice perspective

    NASA Astrophysics Data System (ADS)

    Giusti, Leonardo

    2016-01-01

    I briefly review two recent studies on chiral symmetry breaking in QCD: (a) a computation of the spectral density of the Dirac operator in QCD Lite, (b) a precise determination of the topological charge distribution in the SU(3) Yang-Mills theory as defined by evolving the fundamental gauge field with the Yang-Mills gradient flow equation.

  18. The Coulomb Branch of 3d N= 4 Theories

    NASA Astrophysics Data System (ADS)

    Bullimore, Mathew; Dimofte, Tudor; Gaiotto, Davide

    2017-09-01

    We propose a construction for the quantum-corrected Coulomb branch of a general 3d gauge theory with N=4 supersymmetry, in terms of local coordinates associated with an abelianized theory. In a fixed complex structure, the holomorphic functions on the Coulomb branch are given by expectation values of chiral monopole operators. We construct the chiral ring of such operators, using equivariant integration over BPS moduli spaces. We also quantize the chiral ring, which corresponds to placing the 3d theory in a 2d Omega background. Then, by unifying all complex structures in a twistor space, we encode the full hyperkähler metric on the Coulomb branch. We verify our proposals in a multitude of examples, including SQCD and linear quiver gauge theories, whose Coulomb branches have alternative descriptions as solutions to Bogomolnyi and/or Nahm equations.

  19. QCD thermodynamics on a lattice

    NASA Astrophysics Data System (ADS)

    Levkova, Ludmila A.

    Numerical simulations of full QCD on anisotropic lattices provide a convenient way to study QCD thermodynamics with fixed physics scales and reduced lattice spacing errors. We report results from calculations with two flavors of dynamical staggered fermions, where all bare parameters and the renormalized anisotropy are kept constant and the temperature is changed in small steps by varying only the number of time slices. Including results from zero-temperature scale setting simulations, which determine the Karsch coefficients, allows for the calculation of the Equation of State at finite temperatures. We also report on studies of the chiral properties of dynamical domain-wall fermions combined with the DBW2 gauge action for different gauge couplings and fermion masses. For quenched theories, the DBW2 action gives a residual chiral symmetry breaking much smaller than what was found with more traditional choices for the gauge action. Our goal is to investigate the possibilities which this and further improvements provide for the study of QCD thermodynamics and other simulations at stronger couplings.

  20. Investigating Coulomb's Law.

    ERIC Educational Resources Information Center

    Noll, Ellis; Koehlinger, Mervin; Kowalski, Ludwik; Swackhamer, Gregg

    1998-01-01

    Describes the use of a computer-linked camera to demonstrate Coulomb's law. Suggests a way of reducing the difficulties in presenting Coulomb's law by teaching the inverse square law of gravity and the inverse square law of electricity in the same unit. (AIM)

  1. Diffusion in Coulomb crystals.

    PubMed

    Hughto, J; Schneider, A S; Horowitz, C J; Berry, D K

    2011-07-01

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions "hop" in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter Γ=175 to Coulomb parameters up to Γ=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

  2. Diffusion in Coulomb crystals

    SciTech Connect

    Hughto, J.; Schneider, A. S.; Horowitz, C. J.; Berry, D. K.

    2011-07-15

    Diffusion in Coulomb crystals can be important for the structure of neutron star crusts. We determine diffusion constants D from molecular dynamics simulations. We find that D for Coulomb crystals with relatively soft-core 1/r interactions may be larger than D for Lennard-Jones or other solids with harder-core interactions. Diffusion, for simulations of nearly perfect body-centered-cubic lattices, involves the exchange of ions in ringlike configurations. Here ions ''hop'' in unison without the formation of long lived vacancies. Diffusion, for imperfect crystals, involves the motion of defects. Finally, we find that diffusion, for an amorphous system rapidly quenched from Coulomb parameter {Gamma}=175 to Coulomb parameters up to {Gamma}=1750, is fast enough that the system starts to crystalize during long simulation runs. These results strongly suggest that Coulomb solids in cold white dwarf stars, and the crust of neutron stars, will be crystalline and not amorphous.

  3. On the decoupling between classical Coulomb matter and radiation

    NASA Astrophysics Data System (ADS)

    Alastuey, Angel; Appel, Walter

    2000-02-01

    We consider a model of matter coupled to radiation at equilibrium. Matter is described by a one-component plasma of classical point charges with Coulomb interactions, while radiation is represented by the classical transverse potential vector in Coulomb gauge. Using a straightforward generalization of the Bohr-van Leeuwen theorem, we show that the equilibrium properties of classical Coulomb matter remain unaffected by the presence of the classical radiation. As far as the real world is concerned, this decoupling does survive at large distances where both matter and radiation can be treated classically. This invalidates all the large-distances predictions, for the charge correlations, of the so-called Darwin models which incorporate retarded electromagnetic interactions beyond the instantaneous Coulomb potential. A second related important consequence is that the first relativistic corrections to the Coulomb thermodynamical quantities must be evaluated within the theory of quantum electrodynamics at finite temperature, even in a weakly relativistic and almost classical regime for matter.

  4. Continuous Advances in QCD 2008

    NASA Astrophysics Data System (ADS)

    Peloso, Marco M.

    2008-12-01

    1. High-order calculations in QCD and in general gauge theories. NLO evolution of color dipoles / I. Balitsky. Recent perturbative results on heavy quark decays / J. H. Piclum, M. Dowling, A. Pak. Leading and non-leading singularities in gauge theory hard scattering / G. Sterman. The space-cone gauge, Lorentz invariance and on-shell recursion for one-loop Yang-Mills amplitudes / D. Vaman, Y.-P. Yao -- 2. Heavy flavor physics. Exotic cc¯ mesons / E. Braaten. Search for new physics in B[symbol]-mixing / A. J. Lenz. Implications of D[symbol]-D[symbol] mixing for new physics / A. A. Petrov. Precise determinations of the charm quark mass / M. Steinhauser -- 3. Quark-gluon dynamics at high density and/or high temperature. Crystalline condensate in the chiral Gross-Neveu model / G. V. Dunne, G. Basar. The strong coupling constant at low and high energies / J. H. Kühn. Quarkyonic matter and the phase diagram of QCD / L. McLerran. Statistical QCD with non-positive measure / J. C. Osborn, K. Splittorff, J. J. M. Verbaarschot. From equilibrium to transport properties of strongly correlated fermi liquids / T. Schäfer. Lessons from random matrix theory for QCD at finite density / K. Splittorff, J. J. M. Verbaarschot -- 4. Methods and models of holographic correspondence. Soft-wall dynamics in AdS/QCD / B. Batell. Holographic QCD / N. Evans, E. Threlfall. QCD glueball sum rules and vacuum topology / H. Forkel. The pion form factor in AdS/QCD / H. J. Kwee, R. F. Lebed. The fast life of holographic mesons / R. C. Myers, A. Sinha. Properties of Baryons from D-branes and instantons / S. Sugimoto. The master space of N = 1 quiver gauge theories: counting BPS operators / A. Zaffaroni. Topological field congurations. Skyrmions in theories with massless adjoint quarks / R. Auzzi. Domain walls, localization and confinement: what binds strings inside walls / S. Bolognesi. Static interactions of non-abelian vortices / M. Eto. Vortices which do not abelianize dynamically: semi

  5. 'T hooft anomaly matching for QCD

    SciTech Connect

    Terning, John

    1998-03-03

    I present a set of theories which display non-trivial 'tHooft anomaly matching for QCD with F flavors. The matching theories arenon-Abelian gauge theories with "dual" quarks and baryons, rather thanthe purely confining theories of baryons that 't Hooft originallysearched for. The matching gauge groups are required to have an Fpm 6dimensional representation. Such a correspondence is reminiscent ofSeiberg's duality for supersymmetric (SUSY) QCD, and these theories arecandidates for non-SUSY duality. However anomaly matching by itself isnot sufficiently restrictive, and duality for QCD cannot be establishedat present. At the very least, the existence of multiple anomaly matchingsolutions should provide a note of caution regarding conjectured non-SUSYdualities.

  6. Massively Parallel QCD

    SciTech Connect

    Soltz, R; Vranas, P; Blumrich, M; Chen, D; Gara, A; Giampap, M; Heidelberger, P; Salapura, V; Sexton, J; Bhanot, G

    2007-04-11

    The theory of the strong nuclear force, Quantum Chromodynamics (QCD), can be numerically simulated from first principles on massively-parallel supercomputers using the method of Lattice Gauge Theory. We describe the special programming requirements of lattice QCD (LQCD) as well as the optimal supercomputer hardware architectures that it suggests. We demonstrate these methods on the BlueGene massively-parallel supercomputer and argue that LQCD and the BlueGene architecture are a natural match. This can be traced to the simple fact that LQCD is a regular lattice discretization of space into lattice sites while the BlueGene supercomputer is a discretization of space into compute nodes, and that both are constrained by requirements of locality. This simple relation is both technologically important and theoretically intriguing. The main result of this paper is the speedup of LQCD using up to 131,072 CPUs on the largest BlueGene/L supercomputer. The speedup is perfect with sustained performance of about 20% of peak. This corresponds to a maximum of 70.5 sustained TFlop/s. At these speeds LQCD and BlueGene are poised to produce the next generation of strong interaction physics theoretical results.

  7. The Bayesian reconstruction of the in-medium heavy quark potential from lattice QCD and its stability

    SciTech Connect

    Burnier, Yannis; Kaczmarek, Olaf; Rothkopf, Alexander

    2016-01-22

    We report recent results of a non-perturbative determination of the static heavy-quark potential in quenched and dynamical lattice QCD at finite temperature. The real and imaginary part of this complex quantity are extracted from the spectral function of Wilson line correlators in Coulomb gauge. To obtain spectral information from Euclidean time numerical data, our study relies on a novel Bayesian prescription that differs from the Maximum Entropy Method. We perform simulations on quenched 32{sup 3} × N{sub τ} (β = 7.0, ξ = 3.5) lattices with N{sub τ} = 24, …, 96, which cover 839MeV ≥ T ≥ 210MeV. To investigate the potential in a quark-gluon plasma with light u,d and s quarks we utilize N{sub f} = 2 + 1 ASQTAD lattices with m{sub l} = m{sub s}/20 by the HotQCD collaboration, giving access to temperatures between 286MeV ≥ T ≥ 148MeV. The real part of the potential exhibits a clean transition from a linear, confining behavior in the hadronic phase to a Debye screened form above deconfinement. Interestingly its values lie close to the color singlet free energies in Coulomb gauge at all temperatures. We estimate the imaginary part on quenched lattices and find that it is of the same order of magnitude as in hard-thermal loop perturbation theory. From among all the systematic checks carried out in our study, we discuss explicitly the dependence of the result on the default model and the number of datapoints.

  8. QCD and the BlueGene

    SciTech Connect

    Vranas, P

    2007-06-18

    Quantum Chromodynamics is the theory of nuclear and sub-nuclear physics. It is a celebrated theory and one of its inventors, F. Wilczek, has termed it as '... our most perfect physical theory'. Part of this is related to the fact that QCD can be numerically simulated from first principles using the methods of lattice gauge theory. The computational demands of QCD are enormous and have not only played a role in the history of supercomputers but are also helping define their future. Here I will discuss the intimate relation of QCD and massively parallel supercomputers with focus on the Blue Gene supercomputer and QCD thermodynamics. I will present results on the performance of QCD on the Blue Gene as well as physics simulation results of QCD at temperatures high enough that sub-nuclear matter transitions to a plasma state of elementary particles, the quark gluon plasma. This state of matter is thought to have existed at around 10 microseconds after the big bang. Current heavy ion experiments are in the quest of reproducing it for the first time since then. And numerical simulations of QCD on the Blue Gene systems are calculating the theoretical values of fundamental parameters so that comparisons of experiment and theory can be made.

  9. Gauged supergravities

    NASA Astrophysics Data System (ADS)

    Trigiante, Mario

    2017-03-01

    We give a general review of extended supergravities and their gauging using the duality-covariant embedding tensor formalism. Although the focus is on four-dimensional theories, an overview of the gauging procedure and the related tensor hierarchy in the higher-dimensional models is given. The relation of gauged supergravities to flux compactifications is discussed and examples are worked out in detail.

  10. Electromagnetic instability in holographic QCD

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Oka, Takashi; Sonoda, Akihiko

    2015-06-01

    Using the AdS/CFT correspondence, we calculate the vacuum decay rate for the Schwinger effect in confining large N c gauge theories. The instability is induced by thecorrespondence, we calculate the vacuum quark antiquark pair creation triggered by strong electromagnetic fields. The decay rate is obtained as the imaginary part of the Euler-Heisenberg effective Lagrangian evaluated from the D-brane action with a constant electromagnetic field in holographic QCD models such as the Sakai-Sugimoto model and the deformed Sakai-Sugimoto model. The decay rate is found to increase with the magnetic field parallel to the electric field, while it decreases with the magnetic field perpendicular to the electric field. We discuss generic features of a critical electric field as a function of the magnetic field and the QCD string tension in the Sakai-Sugimoto model.

  11. Bottom-up holographic approach to QCD

    SciTech Connect

    Afonin, S. S.

    2016-01-22

    One of the most known result of the string theory consists in the idea that some strongly coupled gauge theories may have a dual description in terms of a higher dimensional weakly coupled gravitational theory — the so-called AdS/CFT correspondence or gauge/gravity correspondence. The attempts to apply this idea to the real QCD are often referred to as “holographic QCD” or “AdS/QCD approach”. One of directions in this field is to start from the real QCD and guess a tentative dual higher dimensional weakly coupled field model following the principles of gauge/gravity correspondence. The ensuing phenomenology can be then developed and compared with experimental data and with various theoretical results. Such a bottom-up holographic approach turned out to be unexpectedly successful in many cases. In the given short review, the technical aspects of the bottom-up holographic approach to QCD are explained placing the main emphasis on the soft wall model.

  12. Solution of the Gribov problem from gauge invariance

    NASA Astrophysics Data System (ADS)

    Langfeld, K.

    A new approach to gauge fixed Yang-Mills theory is derived using the Polyakov-Susskind projec- tion techniques to build gauge invariant states. In our approach, in contrast to the Faddeev-Popov method, the Gribov problem does not prevent the gauge group from being factored out of the partition function. Lattice gauge theory is used to illustrate the method via a calculation of the static quark-antiquark potential generated by the gauge fields in the fundamental modular region of Coulomb gauge.

  13. Flux tubes in the QCD vacuum

    NASA Astrophysics Data System (ADS)

    Cea, Paolo; Cosmai, Leonardo; Cuteri, Francesca; Papa, Alessandro

    2017-06-01

    The hypothesis that the QCD vacuum can be modeled as a dual superconductor is a powerful tool to describe the distribution of the color field generated by a quark-antiquark static pair and, as such, can provide useful clues for the understanding of confinement. In this work we investigate, by lattice Monte Carlo simulations of the S U (3 ) pure gauge theory and of (2 +1 )-flavor QCD with physical mass settings, some properties of the chromoelectric flux tube at zero temperature and their dependence on the physical distance between the static sources. We draw some conclusions about the validity domain of the dual superconductor picture.

  14. Six dimensional QCD at two loops

    NASA Astrophysics Data System (ADS)

    Gracey, J. A.

    2016-01-01

    We construct the six-dimensional quantum chromodynamics (QCD) Lagrangian in a linear covariant gauge and subsequently renormalize it at two loops in the modified minimal subtraction (MS ¯ ) scheme. The coupling constant corresponding to the gauge interaction is asymptotically free for all numbers of quark fields, Nf. Analyzing the β functions yields a rich spectrum of fixed points. For instance, the conformal window in the six-dimensional theory is at Nf=16 for the S U (3 ) color group. The critical theory structure is similar to that of an O (N ) scalar theory in eight dimensions. Using the large-N expansion the latter is shown to be in the same universality class as the Heisenberg ferromagnet. Similarly using the large-Nf expansion, six-dimensional QCD is shown to be in the same class as the two-dimensional non-Abelian Thirring model and four-dimensional QCD. Abelian gauge theories are also renormalized at high loops in six and eight dimensions. It is shown that the gauge parameter only appears in the electron anomalous dimension at one loop, similar to four dimensions.

  15. Toward large N thermal QCD from dual gravity: The heavy quarkonium potential

    SciTech Connect

    Mia, Mohammed; Dasgupta, Keshav; Gale, Charles; Jeon, Sangyong

    2010-07-15

    We continue our study on the gravity duals for strongly coupled large N QCD with fundamental flavors both at zero and nonzero temperatures. The gravity dual at zero temperature captures the logarithmic runnings of the coupling constants at far IR and the almost conformal, albeit strongly coupled, behavior at the UV. The full UV completion of gauge theory is accomplished in the gravity side by attaching an anti-de Sitter cap to the IR geometry described in our previous work. Attaching such an anti-de Sitter cap is highly nontrivial because it amounts to finding the right interpolating geometry and sources that take us from a gravity solution with nonzero three-form fluxes to another one that has almost vanishing three-form fluxes. In this paper we give a concrete realization of such a scenario, completing the program advocated in our earlier paper. One of the main advantages of having such a background, in addition to providing a dual description of the required gauge theory, is the absence of Landau poles and consequently the UV divergences of the Wilson loops. The potential for the heaviest fundamental quark-antiquark pairs, which are like the heavy quarkonium states in realistic QCD, can be computed and their linear behavior at large separations and zero temperature could be demonstrated. At small separations the expected Coulombic behavior appears to dominate. On the other hand, at nonzero temperatures interesting properties like heavy quarkonium-type suppressions and melting are shown to emerge from our gravity dual. We provide some discussions of the melting temperature and compare our results with the charmonium spectrum and lattice simulations. We argue that, in spite of the large N nature of our construction, certain model-independent predictions can be made.

  16. Jet quenching and gluon to hadron fragmentation function in non-equilibrium QCD at RHIC and LHC

    NASA Astrophysics Data System (ADS)

    Nayak, Gouranga C.

    2017-01-01

    Theoretical understanding of the observed jet quenching measurements at RHIC and LHC is challenging in QCD because it requires understanding of parton to hadron fragmentation function in non-equilibrium QCD. In this paper, by using closed-time path integral formalism, we derive the gauge invariant definition of the gluon to hadron fragmentation function in non-equilibrium QCD which is consistent with factorization theorem in non-equilibrium QCD from first principles.

  17. National Computational Infrastructure for Lattice Gauge Theory

    SciTech Connect

    Brower, Richard C.

    2014-04-15

    SciDAC-2 Project The Secret Life of Quarks: National Computational Infrastructure for Lattice Gauge Theory, from March 15, 2011 through March 14, 2012. The objective of this project is to construct the software needed to study quantum chromodynamics (QCD), the theory of the strong interactions of sub-atomic physics, and other strongly coupled gauge field theories anticipated to be of importance in the energy regime made accessible by the Large Hadron Collider (LHC). It builds upon the successful efforts of the SciDAC-1 project National Computational Infrastructure for Lattice Gauge Theory, in which a QCD Applications Programming Interface (QCD API) was developed that enables lattice gauge theorists to make effective use of a wide variety of massively parallel computers. This project serves the entire USQCD Collaboration, which consists of nearly all the high energy and nuclear physicists in the United States engaged in the numerical study of QCD and related strongly interacting quantum field theories. All software developed in it is publicly available, and can be downloaded from a link on the USQCD Collaboration web site, or directly from the github repositories with entrance linke http://usqcd-software.github.io

  18. QCD instantons and inflation

    NASA Astrophysics Data System (ADS)

    Pack, Lawrence

    In the first half of this dissertation, after giving a pedagogical introduction to quantum chromodynamics, we revisit the question of whether or not one can perform reliable semiclassical QCD computations at zero temperature. We study correlation functions with no perturbative contributions, and organize the problem by means of the operator product expansion, establishing a precise criterion for the validity of a semiclassical calculation. For N ƒ > N, a systematic computation is possible; for Nƒ < N, it is not. N ƒ = N is a borderline case. In our analysis, we see explicitly the exponential suppression of instanton effects at large N. As an application, we describe a test of QCD lattice gauge theory computations in the chiral limit. For the second half, we turn our attention to inflation. Once again, a pedagogical overview of inflation is given, after which we explore some issues in slow roll inflation in situations where field excursions are small compared to Mp. We argue that for small field inflation, minimizing fine tuning requires low energy supersymmetry and a tightly constrained structure. Hybrid inflation is almost an inevitable outcome. The resulting theory can be described in terms of a supersymmetric low energy effective action and inflation completely characterized in terms of a small number of parameters. Demanding slow roll inflation significantly constrains these parameters. In this context, the generic level of fine tuning can be described as a function of the number of light fields, there is an upper bound on the scale of inflation, and an (almost) universal prediction for the spectral index. Models of this type need not suffer from a cosmological moduli problem.

  19. Altered Maxwell equations in the length gauge

    NASA Astrophysics Data System (ADS)

    Reiss, H. R.

    2013-09-01

    The length gauge uses a scalar potential to describe a laser field, thus treating it as a longitudinal field rather than as a transverse field. This distinction is manifested by the fact that the Maxwell equations that relate to the length gauge are not the same as those for transverse fields. In particular, a source term is necessary in the length-gauge Maxwell equations, whereas the Coulomb-gauge description of plane waves possesses the basic property of transverse fields that they propagate with no source terms at all. This difference is shown to be importantly consequential in some previously unremarked circumstances; and it explains why the Göppert-Mayer gauge transformation does not provide the security that might be expected of full gauge equivalence.

  20. SU{sub {ital q}}(2) lattice gauge theory

    SciTech Connect

    Bimonte, G.; Stern, A.; Vitale, P.

    1996-07-01

    We reformulate the Hamiltonian approach to lattice gauge theories such that, at the classical level, the gauge group does not act canonically, but instead as a Poisson-Lie group. At the quantum level, the symmetry gets promoted to a quantum group gauge symmetry. The theory depends on two parameters: the deformation parameter {lambda} and the lattice spacing {ital a}. We show that the system of Kogut and Susskind is recovered when {lambda}{r_arrow}0, while QCD is recovered in the continuum limit (for any {lambda}). We, thus, have the possibility of having a two-parameter regularization of QCD. {copyright} {ital 1996 The American Physical Society.}

  1. Supercoductivity in extended gauge theories

    NASA Astrophysics Data System (ADS)

    Rajput, B. S.; Kumar, Sandeep

    2011-02-01

    Extending the restricted quantum chromodynamics in SU(2) and SU(3) gauge theories by including quarks and gluons and also by reactivating the suppressed dynamical gauge degrees of freedom, the study of dyonic condensation, quark confinement and superconductivity (dual superconductivity as well as color superconductivity) has been undertaken in extended RCD. It has been shown that the global structure of the underlying gauge symmetry of this extended theory exhibits more information than the conventional QCD may do. It has also been shown that at sufficiently high baryon densities, when nucleons get converted into quark matter, the extended RCD is expected to be in one kind or other of the many different possible color superconductivity phases at low temperature.

  2. New QCD sum rules based on canonical commutation relations

    NASA Astrophysics Data System (ADS)

    Hayata, Tomoya

    2012-04-01

    New derivation of QCD sum rules by canonical commutators is developed. It is the simple and straightforward generalization of Thomas-Reiche-Kuhn sum rule on the basis of Kugo-Ojima operator formalism of a non-abelian gauge theory and a suitable subtraction of UV divergences. By applying the method to the vector and axial vector current in QCD, the exact Weinberg’s sum rules are examined. Vector current sum rules and new fractional power sum rules are also discussed.

  3. Holographic models and the QCD trace anomaly

    SciTech Connect

    Jose L. Goity, Roberto C. Trinchero

    2012-08-01

    Five dimensional dilaton models are considered as possible holographic duals of the pure gauge QCD vacuum. In the framework of these models, the QCD trace anomaly equation is considered. Each quantity appearing in that equation is computed by holographic means. Two exact solutions for different dilaton potentials corresponding to perturbative and non-perturbative {beta}-functions are studied. It is shown that in the perturbative case, where the {beta}-function is the QCD one at leading order, the resulting space is not asymptotically AdS. In the non-perturbative case, the model considered presents confinement of static quarks and leads to a non-vanishing gluon condensate, although it does not correspond to an asymptotically free theory. In both cases analyses based on the trace anomaly and on Wilson loops are carried out.

  4. Topological resolution of gauge theory singularities

    SciTech Connect

    Saracco, Fabio; Tomasiello, Alessandro; Torroba, Gonzalo

    2013-08-21

    Some gauge theories with Coulomb branches exhibit singularities in perturbation theory, which are usually resolved by nonperturbative physics. In string theory this corresponds to the resolution of timelike singularities near the core of orientifold planes by effects from F or M theory. We propose a new mechanism for resolving Coulomb branch singularities in three-dimensional gauge theories, based on Chern-Simons interactions. This is illustrated in a supersymmetric S U ( 2 ) Yang-Mills-Chern-Simons theory. We calculate the one-loop corrections to the Coulomb branch of this theory and find a result that interpolates smoothly between the high-energy metric (that would exhibit the singularity) and a regular singularity-free low-energy result. We suggest possible applications to singularity resolution in string theory and speculate a relationship to a similar phenomenon for the orientifold six-plane in massive IIA supergravity.

  5. Vortical susceptibility of finite-density QCD matter

    DOE PAGES

    Aristova, A.; Frenklakh, D.; Gorsky, A.; ...

    2016-10-07

    Here, the susceptibility of finite-density QCD matter to vorticity is introduced, as an analog of magnetic susceptibility. It describes the spin polarization of quarks and antiquarks in finite-density QCD matter induced by rotation. We estimate this quantity in the chirally broken phase using the mixed gauge-gravity anomaly at finite baryon density. It is proposed that the vortical susceptibility of QCD matter is responsible for the polarization of Λ and Λ¯ hyperons observed recently in heavy ion collisions at RHIC by the STAR collaboration.

  6. Lattice QCD for Baryon Rich Matter - Beyond Taylor Expansions

    NASA Astrophysics Data System (ADS)

    Bornyakov, V.; Boyda, D.; Goy, V.; Molochkov, A.; Nakamura, A.; Nikolaev, A.; Zakharov, V. I.

    2016-12-01

    We discuss our study for exploring the QCD phase diagram based on the lattice QCD. To go beyond the Taylor expansion and to reach higher density regions, we employ the canonical approach. In order to produce lattice data which meet experimental situation as much as possible, we propose a canonical approach with the charge and baryon number. We present our lattice QCD GPU code for this project which employs the clover improved Wilson fermions and Iwasaki gauge action to investigate pure imaginary chemical potential.

  7. QCD, unification and the road to asymptopia

    SciTech Connect

    Lindenbaum, S.J.

    1980-11-01

    Attempts to describe interactions at extremely high energies are addressed. Previous beliefs that asymptopia - the theoretically promised land where all asymptotic theorems come true - was reached have always proven false. Present estimates of asymptopia range from 10/sup 5/ GeV to 10/sup 16/ GeV. In the author's opinion it is premature to believe that the universe is described by a hierarchy of nested gauge groups. The establishment of QCD as the nonabelian gauge group describing strong interactions has not yet been accomplished. 2 figures. (RWR)

  8. QCD PHASE TRANSITIONS-VOLUME 15.

    SciTech Connect

    SCHAFER,T.

    1998-11-04

    The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some. efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.

  9. Visualization Tools for Lattice QCD - Final Report

    SciTech Connect

    Massimo Di Pierro

    2012-03-15

    Our research project is about the development of visualization tools for Lattice QCD. We developed various tools by extending existing libraries, adding new algorithms, exposing new APIs, and creating web interfaces (including the new NERSC gauge connection web site). Our tools cover the full stack of operations from automating download of data, to generating VTK files (topological charge, plaquette, Polyakov lines, quark and meson propagators, currents), to turning the VTK files into images, movies, and web pages. Some of the tools have their own web interfaces. Some Lattice QCD visualization have been created in the past but, to our knowledge, our tools are the only ones of their kind since they are general purpose, customizable, and relatively easy to use. We believe they will be valuable to physicists working in the field. They can be used to better teach Lattice QCD concepts to new graduate students; they can be used to observe the changes in topological charge density and detect possible sources of bias in computations; they can be used to observe the convergence of the algorithms at a local level and determine possible problems; they can be used to probe heavy-light mesons with currents and determine their spatial distribution; they can be used to detect corrupted gauge configurations. There are some indirect results of this grant that will benefit a broader audience than Lattice QCD physicists.

  10. Hadron physics as Seiberg dual of QCD

    SciTech Connect

    Kitano, Ryuichiro

    2012-07-27

    We try to identify the light hadron world as the magnetic picture of QCD. We take both phenomenological and theoretical approaches to this hypothesis, and find that the interpretation seems to show interesting consistencies. In particular, one can identify the {rho} and {omega} mesons as the magnetic gauge bosons, and the Higgs mechanism for them provides a dual picture of the color confinement{sup 1}.

  11. Velocity-induced heavy quarkonium dissociation using the gauge-gravity correspondence

    NASA Astrophysics Data System (ADS)

    Patra, Binoy Krishna; Khanchandani, Himanshu; Thakur, Lata

    2015-10-01

    Using the gauge-gravity duality, we have obtained the potential between a heavy quark and an antiquark pair, which is moving perpendicular to the direction of orientation, in a strongly coupled supersymmetric hot plasma. For this purpose we work on a metric in the gravity side, viz. Ouyang-Klebanov-Strassler black hole geometry, of which the dual in the gauge theory side runs with the energy and hence proves to be a better background for thermal QCD. The potential obtained has a confining term both in the vacuum and in a medium, in addition to the Coulomb term alone, usually reported in the literature. As the velocity of the pair is increased, the screening of the potential gets weakened, which may be understood by the decrease of the effective temperature with the increase of the velocity. The crucial observation of our work is that, beyond a critical separation of the heavy quark pair, the potential develops an imaginary part which is nowadays understood to be the main source of dissociation. The imaginary part is found to vanish at small r , thus agreeing with the perturbative result. Finally we have estimated the thermal width for the ground and first excited states and found that nonzero rapidities lead to an increase of thermal width. This implies that the moving quarkonia dissociate more easily than the static ones, which agrees with other calculations. However, the width in our case is larger than other calculations due to the presence of confining terms.

  12. Light-Front Holographic QCD

    SciTech Connect

    Brodsky, Stanley J.; de Teramond, Guy F.; /Costa Rica U.

    2012-02-16

    The relation between the hadronic short-distance constituent quark and gluon particle limit and the long-range confining domain is yet one of the most challenging aspects of particle physics due to the strong coupling nature of Quantum Chromodynamics, the fundamental theory of the strong interactions. The central question is how one can compute hadronic properties from first principles; i.e., directly from the QCD Lagrangian. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time. Lattice numerical results follow from computation of frame-dependent moments of distributions in Euclidean space and dynamical observables in Minkowski spacetime, such as the time-like hadronic form factors, are not amenable to Euclidean lattice computations. The Dyson-Schwinger methods have led to many important insights, such as the infrared fixed point behavior of the strong coupling constant, but in practice, the analyses are limited to ladder approximation in Landau gauge. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. New theoretical tools are thus of primary interest for the interpretation of the results expected at the new mass scale and kinematic regions accessible to the JLab 12 GeV Upgrade Project. The AdS/CFT correspondence between gravity or string theory on a higher-dimensional anti-de Sitter (AdS) space and conformal field theories in physical space-time has led to a semiclassical approximation for strongly-coupled QCD, which provides physical insights into its nonperturbative dynamics. The correspondence is holographic in the sense that it determines a duality between theories in different number of space-time dimensions. This geometric approach leads in fact to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light

  13. QCD propagators and vertices from lattice QCD (in memory of Michael Müller-Preußker)

    NASA Astrophysics Data System (ADS)

    Sternbeck, André

    2017-03-01

    We review lattice calculations of the elementary Greens functions of QCD with a special emphasis on the Landau gauge. These lattice results have been of interest to continuum approaches to QCD over the past 20 years. They are used as reference for Dyson-Schwinger- and functional renormalization group equation calculations as well as for hadronic bound state equations. The lattice provides low-energy data for propagators and three-point vertices in Landau gauge at zero and finite temperature even including dynamical fermions. We summarize Michael Müller-Preußker's important contributions to this field and put them into the perspective of his other research interests.

  14. Semiclassical Coulomb field

    SciTech Connect

    Polonyi, J.

    2008-06-15

    The contribution of different modes of the Coulomb field to decoherence and to the dynamical breakdown of the time reversal invariance is calculated in the one-loop approximation for nonrelativistic electron gas. The dominant contribution was found to come from the usual collective modes in the plasma, namely, the zero-sound and the plasmon oscillations. The length scale of the quantum-classical transition is found to be close to the Thomas-Fermi screening length. It is argued that the extension of these modes to the whole Fock space yields optimal pointer states.

  15. QCD as a topologically ordered system

    SciTech Connect

    Zhitnitsky, Ariel R.

    2013-09-15

    We argue that QCD belongs to a topologically ordered phase similar to many well-known condensed matter systems with a gap such as topological insulators or superconductors. Our arguments are based on an analysis of the so-called “deformed QCD” which is a weakly coupled gauge theory, but nevertheless preserves all the crucial elements of strongly interacting QCD, including confinement, nontrivial θ dependence, degeneracy of the topological sectors, etc. Specifically, we construct the so-called topological “BF” action which reproduces the well known infrared features of the theory such as non-dispersive contribution to the topological susceptibility which cannot be associated with any propagating degrees of freedom. Furthermore, we interpret the well known resolution of the celebrated U(1){sub A} problem where the would be η{sup ′} Goldstone boson generates its mass as a result of mixing of the Goldstone field with a topological auxiliary field characterizing the system. We then identify the non-propagating auxiliary topological field of the BF formulation in deformed QCD with the Veneziano ghost (which plays the crucial role in resolution of the U(1){sub A} problem). Finally, we elaborate on relation between “string-net” condensation in topologically ordered condensed matter systems and long range coherent configurations, the “skeletons”, studied in QCD lattice simulations. -- Highlights: •QCD may belong to a topologically ordered phase similar to condensed matter (CM) systems. •We identify the non-propagating topological field in deformed QCD with the Veneziano ghost. •Relation between “string-net” condensates in CM systems and the “skeletons” in QCD lattice simulations is studied.

  16. Coulomb branch Hilbert series and Hall-Littlewood polynomials

    NASA Astrophysics Data System (ADS)

    Cremonesi, Stefano; Hanany, Amihay; Mekareeya, Noppadol; Zaffaroni, Alberto

    2014-09-01

    There has been a recent progress in understanding the chiral ring of 3d = 4 superconformal gauge theories by explicitly constructing an exact generating function (Hilbert series) counting BPS operators on the Coulomb branch. In this paper we introduce Coulomb branch Hilbert series in the presence of background magnetic charges for flavor symmetries, which are useful for computing the Hilbert series of more general theories through gluing techniques. We find a simple formula of the Hilbert series with background magnetic charges for T ρ ( G) theories in terms of Hall-Littlewood polynomials. Here G is a classical group and ρ is a certain partition related to the dual group of G. The Hilbert series for vanishing background magnetic charges show that Coulomb branches of T ρ ( G) theories are complete intersections. We also demonstrate that mirror symmetry maps background magnetic charges to baryonic charges.

  17. Bethe-Salpeter wave functions of ηc(2 S ) and ψ (2 S ) states from full lattice QCD

    NASA Astrophysics Data System (ADS)

    Nochi, Kazuki; Kawanai, Taichi; Sasaki, Shoichi

    2016-12-01

    We discuss the internal structure of radially excited charmonium mesons based on the equal-time and Coulomb gauge Bethe-Salpeter (BS) amplitudes, which are obtained in lattice QCD. Our simulations are performed with a relativistic heavy-quark action for the charm quark on the (2 +1 )-flavor PACS-CS gauge configurations at the lightest pion mass, Mπ=156 (7 ) MeV . The variational method is applied to the study of the optimal charmonium operators for ground and first excited states of S -wave charmonia. We successfully calculate the BS wave functions of ηc(2 S ) and ψ (2 S ) states, as well as ηc(1 S ) and J /ψ states, and then estimate the root-mean-square radii of both the 1 S and 2 S charmonium states. We also examine whether a series of the BS wave functions from the ground state to excited states can be described by a single set of the spin-independent and spin-dependent interquark potentials with a unique quark mass. It is found that the quark kinetic mass and both the central and the spin-spin charmonium potentials, determined from the 2 S wave functions, fairly agree with the ones from the 1 S wave functions. This strongly supports the validity of the potential description for the charmonium system—at least, below the open-charm threshold.

  18. On gauge independence for gauge models with soft breaking of BRST symmetry

    NASA Astrophysics Data System (ADS)

    Reshetnyak, Alexander

    2014-12-01

    A consistent quantum treatment of general gauge theories with an arbitrary gauge-fixing in the presence of soft breaking of the BRST symmetry in the field-antifield formalism is developed. It is based on a gauged (involving a field-dependent parameter) version of finite BRST transformations. The prescription allows one to restore the gauge-independence of the effective action at its extremals and therefore also that of the conventional S-matrix for a theory with BRST-breaking terms being additively introduced into a BRST-invariant action in order to achieve a consistency of the functional integral. We demonstrate the applicability of this prescription within the approach of functional renormalization group to the Yang-Mills and gravity theories. The Gribov-Zwanziger action and the refined Gribov-Zwanziger action for a many-parameter family of gauges, including the Coulomb, axial and covariant gauges, are derived perturbatively on the basis of finite gauged BRST transformations starting from Landau gauge. It is proved that gauge theories with soft breaking of BRST symmetry can be made consistent if the transformed BRST-breaking terms satisfy the same soft BRST symmetry breaking condition in the resulting gauge as the untransformed ones in the initial gauge, and also without this requirement.

  19. Aging gauge

    DOEpatents

    Betts, Robert E.; Crawford, John F.

    1989-04-04

    An aging gauge comprising a container having a fixed or a variable sized t opening with a cap which can be opened to control the sublimation rate of a thermally sublimational material contained within the container. In use, the aging gauge is stored with an item to determine total heat the item is subjected to and also the maximum temperature to which the item has been exposed. The aging gauge container contains a thermally sublimational material such as naphthalene or similar material which has a low sublimation rate over the temperature range from about 70.degree. F. to about 160.degree. F. The aging products determined by analyses of a like item aged along with the aging gauge for which the sublimation amount is determined is employed to establish a calibration curve for future aging evaluation. The aging gauge is provided with a means for determining the maximum temperature exposure (i.e., a thermally indicating material which gives an irreversible color change, Thermocolor pigment). Because of the relationship of doubling reaction rates for increases of 10.degree. C., equivalency of item used in accelerated aging evaluation can be obtained by referring to a calibration curve depicting storage temperature on the abscissa scale and multiplier on the ordinate scale.

  20. Aging gauge

    DOEpatents

    Betts, Robert E.; Crawford, John F.

    1989-01-01

    An aging gauge comprising a container having a fixed or a variable sized t opening with a cap which can be opened to control the sublimation rate of a thermally sublimational material contained within the container. In use, the aging gauge is stored with an item to determine total heat the item is subjected to and also the maximum temperature to which the item has been exposed. The aging gauge container contains a thermally sublimational material such as naphthalene or similar material which has a low sublimation rate over the temperature range from about 70.degree. F. to about 160.degree. F. The aging products determined by analyses of a like item aged along with the aging gauge for which the sublimation amount is determined is employed to establish a calibration curve for future aging evaluation. The aging gauge is provided with a means for determining the maximum temperature exposure (i.e., a thermally indicating material which gives an irreversible color change, Thermocolor pigment). Because of the relationship of doubling reaction rates for increases of 10.degree. C., equivalency of item used in accelerated aging evaluation can be obtained by referring to a calibration curve depicting storage temperature on the abscissa scale and multiplier on the ordinate scale.

  1. Improved methods for the study of hadronic physics from lattice QCD

    SciTech Connect

    Orginos, Konstantinos; Richards, David G.

    2015-03-01

    The solution of quantum chromodynamics (QCD) on a lattice provides a first-principles method for understanding QCD in the low-energy regime, and is thus an essential tool for nuclear physics. The generation of gauge configurations, the starting point for lattice calculations, requires the most powerful leadership-class computers available. However, to fully exploit such leadership-class computing requires increasingly sophisticated methods for obtaining physics observables from the underlying gauge ensembles. In this paper, we describe a variety of recent methods that have been used to advance our understanding of the spectrum and structure of hadrons through lattice QCD.

  2. Improved methods for the study of hadronic physics from lattice QCD

    SciTech Connect

    Orginos, Kostas; Richards, David

    2015-02-05

    The solution of QCD on a lattice provides a first-principles method for understanding QCD in the low-energy regime, and is thus an essential tool for nuclear physics. The generation of gauge configurations, the starting point for lattice calculations, requires the most powerful leadership-class computers available. However, to fully exploit such leadership-class computing requires increasingly sophisticated methods for obtaining physics observables from the underlying gauge ensembles. In this study, we describe a variety of recent methods that have been used to advance our understanding of the spectrum and structure of hadrons through lattice QCD.

  3. Traceable Coulomb blockade thermometry

    NASA Astrophysics Data System (ADS)

    Hahtela, O.; Mykkänen, E.; Kemppinen, A.; Meschke, M.; Prunnila, M.; Gunnarsson, D.; Roschier, L.; Penttilä, J.; Pekola, J.

    2017-02-01

    We present a measurement and analysis scheme for determining traceable thermodynamic temperature at cryogenic temperatures using Coulomb blockade thermometry. The uncertainty of the electrical measurement is improved by utilizing two sampling digital voltmeters instead of the traditional lock-in technique. The remaining uncertainty is dominated by that of the numerical analysis of the measurement data. Two analysis methods are demonstrated: numerical fitting of the full conductance curve and measuring the height of the conductance dip. The complete uncertainty analysis shows that using either analysis method the relative combined standard uncertainty (k  =  1) in determining the thermodynamic temperature in the temperature range from 20 mK to 200 mK is below 0.5%. In this temperature range, both analysis methods produced temperature estimates that deviated from 0.39% to 0.67% from the reference temperatures provided by a superconducting reference point device calibrated against the Provisional Low Temperature Scale of 2000.

  4. Energies of Screened Coulomb Potentials.

    ERIC Educational Resources Information Center

    Lai, C. S.

    1979-01-01

    This article shows that, by applying the Hellman-Feynman theorem alone to screened Coulomb potentials, the first four coefficients in the energy series in powers of the perturbation parameter can be obtained from the unperturbed Coulomb system. (Author/HM)

  5. Consistent Perturbative Fixed Point Calculations in QCD and Supersymmetric QCD.

    PubMed

    Ryttov, Thomas A

    2016-08-12

    We suggest how to consistently calculate the anomalous dimension γ_{*} of the ψ[over ¯]ψ operator in finite order perturbation theory at an infrared fixed point for asymptotically free theories. If the n+1 loop beta function and n loop anomalous dimension are known, then γ_{*} can be calculated exactly and fully scheme independently in a Banks-Zaks expansion through O(Δ_{f}^{n}), where Δ_{f}=N[over ¯]_{f}-N_{f}, N_{f} is the number of flavors, and N[over ¯]_{f} is the number of flavors above which asymptotic freedom is lost. For a supersymmetric theory, the calculation preserves supersymmetry order by order in Δ_{f}. We then compute γ_{*} through O(Δ_{f}^{2}) for supersymmetric QCD in the dimensional reduction scheme and find that it matches the exact known result. We find that γ_{*} is astonishingly well described in perturbation theory already at the few loops level throughout the entire conformal window. We finally compute γ_{*} through O(Δ_{f}^{3}) for QCD and a variety of other nonsupersymmetric fermionic gauge theories. Small values of γ_{*} are observed for a large range of flavors.

  6. Consistent Perturbative Fixed Point Calculations in QCD and Supersymmetric QCD

    NASA Astrophysics Data System (ADS)

    Ryttov, Thomas A.

    2016-08-01

    We suggest how to consistently calculate the anomalous dimension γ* of the ψ ¯ ψ operator in finite order perturbation theory at an infrared fixed point for asymptotically free theories. If the n +1 loop beta function and n loop anomalous dimension are known, then γ* can be calculated exactly and fully scheme independently in a Banks-Zaks expansion through O (Δfn) , where Δf=N¯ f-Nf , Nf is the number of flavors, and N¯f is the number of flavors above which asymptotic freedom is lost. For a supersymmetric theory, the calculation preserves supersymmetry order by order in Δf. We then compute γ* through O (Δf2) for supersymmetric QCD in the dimensional reduction scheme and find that it matches the exact known result. We find that γ* is astonishingly well described in perturbation theory already at the few loops level throughout the entire conformal window. We finally compute γ* through O (Δf3) for QCD and a variety of other nonsupersymmetric fermionic gauge theories. Small values of γ* are observed for a large range of flavors.

  7. Miracles in Scattering Amplitudes: from QCD to Gravity

    SciTech Connect

    Volovich, Anastasia

    2016-10-09

    The goal of my research project "Miracles in Scattering Amplitudes: from QCD to Gravity" involves deepening our understanding of gauge and gravity theories by exploring hidden structures in scattering amplitudes and using these rich structures as much as possible to aid practical calculations.

  8. Transverse momentum dependent quark densities from Lattice QCD

    SciTech Connect

    Musch, B. U.; Haegler, Ph.; Negele, J. W.; Schaefer, A.

    2011-10-24

    We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. We discuss the basic concepts of the method, including renormalization of the gauge link. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.

  9. Transverse momentum dependent quark densities from Lattice QCD

    SciTech Connect

    Bernhard Musch,Philipp Hagler,John Negele,Andreas Schafer

    2011-10-01

    We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. We discuss the basic concepts of the method, including renormalization of the gauge link. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities.

  10. Coulomb blockade and Coulomb staircase behavior observed at room temperature

    NASA Astrophysics Data System (ADS)

    Uky Vivitasari, Pipit; Azuma, Yasuo; Sakamoto, Masanori; Teranishi, Toshiharu; Majima, Yutaka

    2017-02-01

    A single-electron transistor (SET) consists of source, drain, Coulomb island, and gate to modulate the number of electrons and control the current. For practical applications, it is important to operate a SET at room temperature. One proposal towards the ability to operate at room temperature is to decrease Coulomb island size down to a few nanometres. We investigate a SET using Sn-porphyrin (Sn-por) protected gold nanoparticles (AuNPs) with 1.4 nm in core diameter as a Coulomb island. The fabrication method of nanogap electrodes uses the combination of a top-down technique by electron beam lithography (EBL) and a bottom-up process through electroless gold plating (ELGP) as our group have described before. The electrical measurement was conducted at room temperature (300 K). From current-voltage (I d-V d) characteristics, we obtained clear Coulomb blockade phenomena together with a Coulomb staircase due to a Sn-por protected gold NP as a Coulomb island. Experimental results of I d-V d characteristics agree with a theoretical curve based on using the orthodox model. Clear dI d/dV d peaks are observed in the Coulomb staircase at 9 K which suggest the electron transports through excited energy levels of Au NPs. These results are a big step for obtaining SETs that can operate at room temperature.

  11. Quenching parameter in a holographic thermal QCD

    NASA Astrophysics Data System (ADS)

    Patra, Binoy Krishna; Arya, Bhaskar

    2017-01-01

    We have calculated the quenching parameter, q ˆ in a model-independent way using the gauge-gravity duality. In earlier calculations, the geometry in the gravity side at finite temperature was usually taken as the pure AdS black hole metric for which the dual gauge theory becomes conformally invariant unlike QCD. Therefore we use a metric which incorporates the fundamental quarks by embedding the coincident D7 branes in the Klebanov-Tseytlin background and a finite temperature is switched on by inserting a black hole into the background, known as OKS-BH metric. Further inclusion of an additional UV cap to the metric prepares the dual gauge theory to run similar to thermal QCD. Moreover q ˆ is usually defined in the literature from the Glauber model perturbative QCD evaluation of the Wilson loop, which has no reasons to hold if the coupling is large and is thus against the main idea of gauge-gravity duality. Thus we use an appropriate definition of q ˆ : q ˆ L- = 1 /L2, where L is the separation for which the Wilson loop is equal to some specific value. The above two refinements cause q ˆ to vary with the temperature as T4 always and to depend linearly on the light-cone time L- with an additional (1 /L-) correction term in the short-distance limit whereas in the long-distance limit, q ˆ depends only linearly on L- with no correction term. These observations agree with other holographic calculations directly or indirectly.

  12. Phenomenology of strongly coupled chiral gauge theories

    SciTech Connect

    Bai, Yang; Berger, Joshua; Osborne, James; Stefanek, Ben A.

    2016-11-25

    A sector with QCD-like strong dynamics is common in models of non-standard physics. Such a model could be accessible in LHC searches if both confinement and big-quarks charged under the confining group are at the TeV scale. Big-quark masses at this scale can be explained if the new fermions are chiral under a new U(1)' gauge symmetry such that their bare masses are related to the U(1)'-breaking and new confinement scales. Here we present a study of a minimal GUT-motivated and gauge anomaly-free model with implications for the LHC Run 2 searches. We find that the first signatures of such models could appear as two gauge boson resonances. The chiral nature of the model could be confirmed by observation of a Z'γ resonance, where the Z' naturally has a large leptonic branching ratio because of its kinetic mixing with the hypercharge gauge boson.

  13. Gauge-invariant approach to quark dynamics

    NASA Astrophysics Data System (ADS)

    Sazdjian, H.

    2016-02-01

    The main aspects of a gauge-invariant approach to the description of quark dynamics in the nonperturbative regime of quantum chromodynamics (QCD) are first reviewed. The role of the parallel transport operation in constructing gauge-invariant Green's functions is then presented, and the relevance of Wilson loops for the representation of the interaction is emphasized. Recent developments, based on the use of polygonal lines for the parallel transport operation, are presented. An integro-differential equation, obtained for the quark Green's function defined with a phase factor along a single, straight line segment, is solved exactly and analytically in the case of two-dimensional QCD in the large- N c limit. The solution displays the dynamical mass generation phenomenon for quarks, with an infinite number of branch-cut singularities that are stronger than simple poles.

  14. World Sheet Dynamics of Effective String Theory and the Gribov Ambiguity in QCD

    NASA Astrophysics Data System (ADS)

    Cooper, Patrick

    This PhD thesis consists of a collection of results pertaining to effective string theory and quantum chromodynamics. A bijection is proven between manifestly ISO(1, p) x SO(D - p - 1) actions whose gapless degrees of freedom consist of Goldstone fields realizing the coset ISO(1, D - 1)/ISO(1, p) x SO(D - p - 1) non-linearly, and effective actions describing p + 1 dimensional surfaces embedded in a D dimensional Minkowskian target space. Continuing with effective strings, an interesting UV complete, albeit acausal theory is analyzed whose low energy effective action has a 'wrong sign' leading irrelevant operator. The constraints integrability puts on branon scattering is also catalogued in various dimensions, and in the presence of goldstini non-linearly realizing target space supersymmetry. An interesting hidden supersymmetry is discovered, for Green-Schwarz-like actions with an arbitrary coefficient preceding the Wess-Zumino term. Lastly, with regards to QCD, techniques from the program initiated by Vladimir Gribov in 1978 to investigate the effects of a non-perturbative residual gauge ambiguity are refined and applied to the Gribov-Zwanziger confinement scenario, showing an enhanced ghost propagator and divergent color coulomb potential. I then provide a careful analysis of how to correctly implement periodic boundary conditions in the finite temperature theory, which naively would be contradictory with the Maggiore-Schaden shift which is crucial to using familiar BRST cohomology techniques to define the subset of physical states of the Hilbert space.

  15. Conformal Symmetry as a Template for QCD

    SciTech Connect

    Brodsky, S

    2004-08-04

    Conformal symmetry is broken in physical QCD; nevertheless, one can use conformal symmetry as a template, systematically correcting for its nonzero {beta} function as well as higher-twist effects. For example, commensurate scale relations which relate QCD observables to each other, such as the generalized Crewther relation, have no renormalization scale or scheme ambiguity and retain a convergent perturbative structure which reflects the underlying conformal symmetry of the classical theory. The ''conformal correspondence principle'' also dictates the form of the expansion basis for hadronic distribution amplitudes. The AdS/CFT correspondence connecting superstring theory to superconformal gauge theory has important implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for hard exclusive processes as well as determining essential aspects of hadronic light-front wavefunctions. Theoretical and phenomenological evidence is now accumulating that QCD couplings based on physical observables such as {tau} decay become constant at small virtuality; i.e., effective charges develop an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. The near-constant behavior of effective couplings also suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer. The importance of using an analytic effective charge such as the pinch scheme for unifying the electroweak and strong couplings and forces is also emphasized.

  16. Finite-size effects of hadron masses in lattice QCD: A comparative study for quenched and full QCD simulations

    SciTech Connect

    Aoki, S.; Umemura, T.; Fukugita, M.; Ishizuka, N.; Mino, H.; Okawa, M.; Ukawa, A. Yukawa Institute, Kyoto University, Kyoto 606 Faculty of Engineering, Yamanashi University, Kofu 404 National Laboratory for High Energy Physics , Tsukuba, Ibaraki 305 )

    1994-07-01

    A study of finite-size effects is carried out for hadron masses in the quenched simulation of lattice QCD using the Kogut-Susskind quark action. It is found that finite-size effects for quenched QCD are much smaller than those for full QCD, when hadron masses for the two cases are compared at the same physical lattice size and lattice spacing. Based on an extensive study of the boundary condition dependence of hadron masses we ascribe the origin of the difference to a partial cancellation of the finite-size effects among the [ital Z](3)-related gauge configurations in quenched QCD; such a cancellation does not take place in full QCD due to [ital Z](3) breaking effects of dynamical quarks. However, this does not mean finite-size errors are negligible in quenched QCD for lattice sizes of 2 to 3 fm used in current simulations; a still significant finite-size shift of hadron masses, especially of the nucleon mass, would pose a serious hindrance to obtaining the hadron mass spectrum at the few percent level aimed at in current quenched QCD simulations.

  17. QCD results at CDF

    SciTech Connect

    Norniella, Olga; /Barcelona, IFAE

    2005-01-01

    Recent QCD measurements from the CDF collaboration at the Tevatron are presented, together with future prospects as the luminosity increases. The measured inclusive jet cross section is compared to pQCD NLO predictions. Precise measurements on jet shapes and hadronic energy flows are compared to different phenomenological models that describe gluon emissions and the underlying event in hadron-hadron interactions.

  18. Proton spin structure from lattice QCD

    SciTech Connect

    Fukugita, M.; Kuramashi, Y.; Okawa, M.; Ukawa, A. ||

    1995-09-11

    A lattice QCD calculation of the proton matrix element of the flavor singlet axial-vector current is reported. Both the connected and disconnected contributions are calculated, for the latter employing the variant method of wall source without gauge fixing. From simulations in quenched QCD with the Wilson quark action on a 16{sup 3}{times}20 lattice at {beta}=5.7 (the lattice spacing {ital a}{approx}0.14 fm), we find {Delta}{Sigma}={Delta}{ital u}+{Delta}{ital d}+{Delta}{ital s}=+0.638(54){minus}0.347(46){minus}0.109(30)=+0.18(10) with the disconnected contribution to {Delta}{ital u} and {Delta}{ital d} equal to {minus}0.119(44), which is reasonably consistent with the experiment.

  19. eta and eta' Mesons from Lattice QCD

    SciTech Connect

    Christ, N.H.; Izubuchi, T.; Dawson, C.; Jung, C.; Liu, Q.; Mawhinney, R.D.; Sachrajda, C.T.; Soni, A.; Zhou, R.

    2010-12-08

    The large mass of the ninth pseudoscalar meson, the {eta}{prime}, is believed to arise from the combined effects of the axial anomaly and the gauge field topology present in QCD. We report a realistic, 2+1-flavor, lattice QCD calculation of the {eta} and {eta}{prime} masses and mixing which confirms this picture. The physical eigenstates show small octet-singlet mixing with a mixing angle of {theta} = -14.1(2.8){sup o}. Extrapolation to the physical light quark mass gives, with statistical errors only, m{sub {eta}} = 573(6) MeV and m{sub {eta}} = 947(142) MeV, consistent with the experimental values of 548 and 958 MeV.

  20. η and η' mesons from lattice QCD.

    PubMed

    Christ, N H; Dawson, C; Izubuchi, T; Jung, C; Liu, Q; Mawhinney, R D; Sachrajda, C T; Soni, A; Zhou, R

    2010-12-10

    The large mass of the ninth pseudoscalar meson, the η', is believed to arise from the combined effects of the axial anomaly and the gauge field topology present in QCD. We report a realistic, 2+1-flavor, lattice QCD calculation of the η and η' masses and mixing which confirms this picture. The physical eigenstates show small octet-singlet mixing with a mixing angle of θ=-14.1(2.8)°. Extrapolation to the physical light quark mass gives, with statistical errors only, mη=573(6) MeV and mη'=947(142) MeV, consistent with the experimental values of 548 and 958 MeV.

  1. Classification of QCD defects via holography

    NASA Astrophysics Data System (ADS)

    Gorsky, Alexander S.; Zakharov, Valentin I.; Zhitnitsky, Ariel R.

    2009-05-01

    We discuss classification of defects of various codimensions within a holographic model of pure Yang-Mills theories or gauge theories with fundamental matter. We focus on their role below and above the phase transition point as well as their weights in the partition function. The general result is that objects which are stable and heavy in one phase are becoming very light (tensionless) in the other phase. We argue that the θ dependence of the partition function drastically changes at the phase transition point, and therefore it correlates with stability properties of configurations. We also explore the possibility that novel stable glueballlike particles, with mass which scales like Nc and which are analogous to carbon Fullerenes, may exist in nature on the QCD scale. Some possible applications for studying the QCD vacuum properties above and below the phase transition are also discussed.

  2. An Analytic Approach to Perturbative QCD

    NASA Astrophysics Data System (ADS)

    Magradze, B. A.

    The two-loop invariant (running) coupling of QCD is written in terms of the Lambert W function. The analyticity structure of the coupling in the complex Q2-plane is established. The corresponding analytic coupling is reconstructed via a dispersion relation. We also consider some other approximations to the QCD β-function, when the corresponding couplings are solved in terms of the Lambert function. The Landau gauge gluon propagator has been considered in the renormalization group invariant analytic approach (IAA). It is shown that there is a nonperturbative ambiguity in determination of the anomalous dimension function of the gluon field. Several analytic solutions for the propagator at the one-loop order are constructed. Properties of the obtained analytical solutions are discussed.

  3. Hadronization of QCD and effective interactions

    SciTech Connect

    Frank, M.R.

    1994-07-01

    An introductory treatment of hadronization through functional integral calculus and bifocal Bose fields is given. Emphasis is placed on the utility of this approach for providing a connection between QCD and effective hadronic field theories. The hadronic interactions obtained by this method are nonlocal due to the QCD substructure, yet, in the presence of an electromagnetic field, maintain the electromagnetic gauge invariance manifest at the quark level. A local chiral model which is structurally consistent with chiral perturbation theory is obtained through a derivative expansion of the nonlocalities with determined, finite coefficients. Tree-level calculations of the pion form factor and {pi} {minus} {pi} scattering, which illustrate the dual constituent-quark-chiral-model nature of this approach, are presented.

  4. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule

    NASA Astrophysics Data System (ADS)

    Cloët, Ian C.; Bentz, Wolfgang; Thomas, Anthony W.

    2016-01-01

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q |≳0.5 GeV . The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei.

  5. Relativistic and Nuclear Medium Effects on the Coulomb Sum Rule.

    PubMed

    Cloët, Ian C; Bentz, Wolfgang; Thomas, Anthony W

    2016-01-22

    In light of the forthcoming high precision quasielastic electron scattering data from Jefferson Lab, it is timely for the various approaches to nuclear structure to make robust predictions for the associated response functions. With this in mind, we focus here on the longitudinal response function and the corresponding Coulomb sum rule for isospin-symmetric nuclear matter at various baryon densities. Using a quantum field-theoretic quark-level approach which preserves the symmetries of quantum chromodynamics, as well as exhibiting dynamical chiral symmetry breaking and quark confinement, we find a dramatic quenching of the Coulomb sum rule for momentum transfers |q|≳0.5  GeV. The main driver of this effect lies in changes to the proton Dirac form factor induced by the nuclear medium. Such a dramatic quenching of the Coulomb sum rule was not seen in a recent quantum Monte Carlo calculation for carbon, suggesting that the Jefferson Lab data may well shed new light on the explicit role of QCD in nuclei.

  6. Lattice QCD simulation with the overlap Dirac operator

    NASA Astrophysics Data System (ADS)

    Howard, Joseph

    A complete understanding of the predictions of Quantum Chromodynamics (QCD) will be an important part of moving particle physics beyond the current Standard Model. At the energy scales relevant to bound QCD systems, such as the pion and the proton, non-perturbative techniques must be used to estimate QCD predictions. The non-perturbative method used to investigate QCD is lattice QCD, or QCD on a discrete spacetime lattice. One aspect of continuum QCD that should be preserved in lattice QCD is chiral symmetry. The inability of maintaining such symmetry in the discretization of the Dirac equation has for years been a shortcoming of lattice QCD. Recently, however, Neuberger has introduced the overlap Dirac operator, which preserves exact chiral symmetry, even at finite lattice spacing. This dissertation describes a simulation of lattice QCD using the Wilson gauge action and the overlap Dirac operator, performed on two separate lattices. The first was an 183 x 64 lattice (where the first number represents the spatial extent and the second the extent in time) with coupling beta = 6.0 (lattice spacing a-1 ≃ 2.0 GeV), and the second a 143 x 48 lattice with coupling beta = 5.85 (lattice spacing a-1 ≃ 1.5 GeV). The finer 183 x 64 lattice size was chosen in order to allow a large enough extent in time for prediction of QCD observables that previous investigations using smaller lattices were unable to predict. The coarser 143 x 48 lattice was chosen to have roughly the same physical volume as the finer lattice, allowing for an investigation into scaling effects. The dissertation begins with a review of the basics of QCD and lattice QCD, including descriptions of the overlap Dirac operator and chiral symmetry on the lattice. Next, the results from the two simulations are presented. The chiral nature of the overlap Dirac operator is confirmed. The light hadron spectrum is presented, along with decay constants and other observables. An investigation is described on the use

  7. Interpolating the Coulomb phase of little string theory

    SciTech Connect

    Lin, Ying -Hsuan; Shao, Shu -Heng; Wang, Yifan; Yin, Xi

    2015-12-03

    We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.

  8. Interpolating the Coulomb phase of little string theory

    DOE PAGES

    Lin, Ying -Hsuan; Shao, Shu -Heng; Wang, Yifan; ...

    2015-12-03

    We study up to 8-derivative terms in the Coulomb branch effective action of (1,1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity onmore » the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k=2,3,4,5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. As a result, we also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2,0) little string theory.« less

  9. Extracting electric polarizabilities from lattice QCD

    SciTech Connect

    Detmold, W.; Tiburzi, B. C.; Walker-Loud, A.

    2009-05-01

    Charged and neutral, pion and kaon electric polarizabilities are extracted from lattice QCD using an ensemble of anisotropic gauge configurations with dynamical clover fermions. We utilize classical background fields to access the polarizabilities from two-point correlation functions. Uniform background fields are achieved by quantizing the electric field strength with the proper treatment of boundary flux. These external fields, however, are implemented only in the valence quark sector. A novel method to extract charge particle polarizabilities is successfully demonstrated for the first time.

  10. Extracting Electric Polarizabilities from Lattice QCD

    SciTech Connect

    Will Detmold, William Detmold, Brian Tiburzi, Andre Walker-Loud

    2009-05-01

    Charged and neutral, pion and kaon electric polarizabilities are extracted from lattice QCD using an ensemble of anisotropic gauge configurations with dynamical clover fermions. We utilize classical background fields to access the polarizabilities from two-point correlation functions. Uniform background fields are achieved by quantizing the electric field strength with the proper treatment of boundary flux. These external fields, however, are implemented only in the valence quark sector. A novel method to extract charge particle polarizabilities is successfully demonstrated for the first time.

  11. Three loop cusp anomalous dimension in QCD.

    PubMed

    Grozin, Andrey; Henn, Johannes M; Korchemsky, Gregory P; Marquard, Peter

    2015-02-13

    We present the full analytic result for the three loop angle-dependent cusp anomalous dimension in QCD. With this result, infrared divergences of planar scattering processes with massive particles can be predicted to that order. Moreover, we define a closely related quantity in terms of an effective coupling defined by the lightlike cusp anomalous dimension. We find evidence that this quantity is universal for any gauge theory and use this observation to predict the nonplanar n(f)-dependent terms of the four loop cusp anomalous dimension.

  12. Lattice QCD in rotating frames.

    PubMed

    Yamamoto, Arata; Hirono, Yuji

    2013-08-23

    We formulate lattice QCD in rotating frames to study the physics of QCD matter under rotation. We construct the lattice QCD action with the rotational metric and apply it to the Monte Carlo simulation. As the first application, we calculate the angular momenta of gluons and quarks in the rotating QCD vacuum. This new framework is useful to analyze various rotation-related phenomena in QCD.

  13. Predictive Lattice QCD

    SciTech Connect

    Kronfeld, Andreas

    2005-09-21

    Quantum chromodynamics (QCD) is the quantum field theory describing the strong interactions of quarks bound inside hadrons. It is marvelous theory, which works (mathematically) at all distance scales. Indeed, for thirty years, theorists have known how to calculate short-distance properties of QCD, thanks to the (Nobel-worthy) idea of asymptotic freedom. More recently, numerical techniques applied to the strong-coupling regime of QCD have enabled us to compute long-distance bound-state properties. In this colloquium, we review these achievements and show how the new-found methods of calculation will influence high-energy physics.

  14. Lattice QCD for nuclei

    NASA Astrophysics Data System (ADS)

    Beane, Silas

    2016-09-01

    Over the last several decades, theoretical nuclear physics has been evolving from a very-successful phenomenology of the properties of nuclei, to a first-principles derivation of the properties of visible matter in the Universe from the known underlying theories of Quantum Chromodynamics (QCD) and Electrodynamics. Many nuclear properties have now been calculated using lattice QCD, a method for treating QCD numerically with large computers. In this talk, some of the most recent results in this frontier area of nuclear theory will be reviewed.

  15. Lattice QCD computations: Recent progress with modern Krylov subspace methods

    SciTech Connect

    Frommer, A.

    1996-12-31

    Quantum chromodynamics (QCD) is the fundamental theory of the strong interaction of matter. In order to compare the theory with results from experimental physics, the theory has to be reformulated as a discrete problem of lattice gauge theory using stochastic simulations. The computational challenge consists in solving several hundreds of very large linear systems with several right hand sides. A considerable part of the world`s supercomputer time is spent in such QCD calculations. This paper presents results on solving systems for the Wilson fermions. Recent progress is reviewed on algorithms obtained in cooperation with partners from theoretical physics.

  16. Application of Fixed Scale Approach to Static Quark Free Energies in Quenched and 2+1 Flavor Lattice QCD with Improved Wilson Quark Action

    NASA Astrophysics Data System (ADS)

    Maezawa, Y.; Umeda, T.; Aoki, S.; Ejiri, S.; Hatsuda, T.; Kanaya, K.; Ohno, H.; WHOT-QCD Collaboration

    2012-11-01

    The free energies of static quarks and the Debye screening masses in the quark gluon plasma are studied using Polyakov-line correlation functions in lattice QCD adopting the fixed-scale approach in which temperature is varied without changing the spatial volume and the renormalization factors. We calculate static-quark free energies in various color channels in the high temperature phase up to about 3.5 times the (pseudo-)critical temperature, performing lattice simulations both in quenched and 2 + 1 flavor QCD. For the quenched simulations, we adopt the plaquette gauge action on anisotropic 20^3 × N_t lattices with N_t = 8-26 at the renormalized anisotropy a_s / a_t ≃ 4. For 2 + 1 flavor QCD, we adopt the renormalization-group improved Iwasaki gluon action and the non-perturbatively O(a)-improved Wilson quark action on isotropic 32^3 × N_t lattices with N_t = 4-12 at m_{PS}/m_{V} = 0.63 (0.74) for the light (strange) flavors. We find that the color-singlet free energies at high temperatures converge to the zero-temperature static-quark potential evaluated from the Wilson-loop at short distances. This is in accordance with the theoretical expectation that the short distance physics is insensitive to the temperature. At long distances, the free energies approach twice the single-quark free energies, implying that the interaction between static quarks is fully screened. We find that the static-quark free energies for various color channels turn out to be well described by the screened Coulomb form, and the color-channel dependence of the inter-quark interaction can be described by the kinetic Casimir factor inspired from the lowest order perturbation theory. We also discuss comparison with a prediction of the thermal perturbation theory and flavor dependence of the screening masses.

  17. Orbital ice: An exact Coulomb phase on the diamond lattice

    SciTech Connect

    Chern Giawei; Wu Congjun

    2011-12-15

    We demonstrate the existence of an orbital Coulomb phase as the exact ground state of a p-orbital exchange Hamiltonian on the diamond lattice. The Coulomb phase is an emergent state characterized by algebraic dipolar correlations and a gauge structure resulting from local constraints (ice rules) of the underlying lattice models. For most ice models on the pyrochlore lattice, these local constraints are a direct consequence of minimizing the energy of each individual tetrahedron. On the contrary, the orbital ice rules are emergent phenomena resulting from the quantum orbital dynamics. We show that the orbital ice model exhibits an emergent geometrical frustration by mapping the degenerate quantum orbital ground states to the spin-ice states obeying the 2-in-2-out constraints on the pyrochlore lattice. We also discuss possible realization of the orbital ice model in optical lattices with p-band fermionic cold atoms.

  18. Advances in Light-Front QCD and New Perspectives for QCD from AdS/CFT

    SciTech Connect

    Brodsky, Stanley J.; de Teramond, Guy F.; /Costa Rica U.

    2005-10-26

    The light-front quantization of gauge theories in light-cone gauge provides a frame-independent wavefunction representation of relativistic bound states, simple forms for current matrix elements, explicit unitarity, and a Fock space built on a trivial vacuum. The AdS/CFT correspondence has led to important insights into the properties of quantum chromodynamics even though QCD is a broken conformal theory. We have recently shown how a model based on a truncated AdS space can be used to obtain the hadronic spectrum of q{bar q}, qqq and gg bound states, as well as their respective light-front wavefunctions. Specific hadrons are identified by the correspondence of string modes with the dimension of the interpolating operator of the hadron's valence Fock state, including orbital angular momentum excitations. The predicted mass spectrum is linear M {proportional_to} L at high orbital angular momentum, in contrast to the quadratic dependence M{sup 2}/L found in the description of spinning strings. Since only one parameter, the QCD scale {Lambda}{sub QCD}, is introduced, the agreement with the pattern of physical states is remarkable. In particular, the ratio of {Delta} to nucleon trajectories is determined by the ratio of zeros of Bessel functions. As a specific application of QCD dynamics from AdS/CFT duality, we describe a computation of the proton magnetic form factor in both the space-like and time-like regions. The extended AdS/CFT space-time theory also provides an analytic model for hadronic light-front wavefunctions, thus providing a relativistic description of hadrons in QCD at the amplitude level. The model wavefunctions display confinement at large inter-quark separation and conformal symmetry at short distances. In particular, the scaling and conformal properties of the LFWFs at high relative momenta agree with perturbative QCD. These AdS/CFT model wavefunctions could be used as an initial ansatz for a variational treatment of the light-front QCD Hamiltonian.

  19. Strong Coupling Gauge Theories in LHC ERA

    NASA Astrophysics Data System (ADS)

    Fukaya, H.; Harada, M.; Tanabashi, M.; Yamawaki, K.

    2011-01-01

    AdS/QCD, light-front holography, and the nonperturbative running coupling / Stanley J. Brodsky, Guy de Teramond and Alexandre Deur -- New results on non-abelian vortices - Further insights into monopole, vortex and confinement / K. Konishi -- Study on exotic hadrons at B-factories / Toru Iijima -- Cold compressed baryonic matter with hidden local symmetry and holography / Mannque Rho -- Aspects of baryons in holographic QCD / T. Sakai -- Nuclear force from string theory / K. Hashimoto -- Integrating out holographic QCD back to hidden local symmetry / Masayasu Harada, Shinya Matsuzaki and Koichi Yamawaki -- Holographic heavy quarks and the giant Polyakov loop / Gianluca Grignani, Joanna Karczmarek and Gordon W. Semenoff -- Effect of vector-axial-vector mixing to dilepton spectrum in hot and/or dense matter / Masayasu Harada and Chihiro Sasaki -- Infrared behavior of ghost and gluon propagators compatible with color confinement in Yang-Mills theory with the Gribov horizon / Kei-Ichi Kondo -- Chiral symmetry breaking on the lattice / Hidenori Fukaya [for JLQCD and TWQCD collaborations] -- Gauge-Higgs unification: Stable Higgs bosons as cold dark matter / Yutaka Hosotani -- The limits of custodial symmetry / R. Sekhar Chivukula ... [et al.] -- Higgs searches at the tevatron / Kazuhiro Yamamoto [for the CDF and D[symbol] collaborations] -- The top triangle moose / R. S. Chivukula ... [et al.] -- Conformal phase transition in QCD like theories and beyond / V. A. Miransky -- Gauge-Higgs unification at LHC / Nobuhito Maru and Nobuchika Okada -- W[symbol]W[symbol] scattering in Higgsless models: Identifying better effective theories / Alexander S. Belyaev ... [et al.] -- Holographic estimate of Muon g - 2 / Deog Ki Hong -- Gauge-Higgs dark matter / T. Yamashita -- Topological and curvature effects in a multi-fermion interaction model / T. Inagaki and M. Hayashi -- A model of soft mass generation / J. Hosek -- TeV physics and conformality / Thomas Appelquist -- Conformal

  20. Soft QCD at Tevatron

    SciTech Connect

    Rangel, Murilo; /Orsay, LAL

    2010-06-01

    Experimental studies of soft Quantum Chromodynamics (QCD) at Tevatron are reported in this note. Results on inclusive inelastic interactions, underlying events, double parton interaction and exclusive diffractive production and their implications to the Large Hadron Collider (LHC) physics are discussed.

  1. Resonances in QCD

    SciTech Connect

    Lutz, Matthias F. M.; Lange, Jens Sören; Pennington, Michael; Bettoni, Diego; Brambilla, Nora; Crede, Volker; Eidelman, Simon; Gillitzer, Albrecht; Gradl, Wolfgang; Lang, Christian B.; Metag, Volker; Nakano, Takashi; Nieves, Juan; Neubert, Sebastian; Oka, Makoto; Olsen, Stephen L.; Pappagallo, Marco; Paul, Stephan; Pelizäus, Marc; Pilloni, Alessandro; Prencipe, Elisabetta; Ritman, Jim; Ryan, Sinead; Thoma, Ulrike; Uwer, Ulrich; Weise, Wolfram

    2016-04-01

    We report on the EMMI Rapid Reaction Task Force meeting 'Resonances in QCD', which took place at GSI October 12-14, 2015 (Fig.~1). A group of 26 people met to discuss the physics of resonances in QCD. The aim of the meeting was defined by the following three key questions; what is needed to understand the physics of resonances in QCD?; where does QCD lead us to expect resonances with exotic quantum numbers?; and what experimental efforts are required to arrive at a coherent picture? For light mesons and baryons only those with up, down and strange quark content were considered. For heavy-light and heavy-heavy meson systems, those with charm quarks were the focus.This document summarizes the discussions by the participants, which in turn led to the coherent conclusions we present here.

  2. QCD Evolution 2016

    NASA Astrophysics Data System (ADS)

    The QCD Evolution 2016 workshop was held at the National Institute for Subatomic Physics (Nikhef) in Amsterdam, May 30 - June 3, 2016. The workshop is a continuation of a series of workshops held during five consecutive years, in 2011, 2012, 2013, 2015 at Jefferson Lab, and in 2014 in Santa Fe, NM. With the rapid developments in our understanding of the evolution of parton distributions including low-x, TMDs, GPDs, higher-twist correlation functions, and the associated progress in perturbative QCD, lattice QCD and effective field theory techniques, we look forward to yet another exciting meeting in 2016. The program of QCD Evolution 2016 will pay special attention to the topics of importance for ongoing experiments, in the full range from Jefferson Lab energies to LHC energies or future experiments such as a future Electron Ion Collider, recently recommended as a highest priority in U.S. Department of Energy's 2015 Long Range Plan for Nuclear Science.

  3. The QCD running coupling

    NASA Astrophysics Data System (ADS)

    Deur, Alexandre; Brodsky, Stanley J.; de Téramond, Guy F.

    2016-09-01

    We review the present theoretical and empirical knowledge for αs, the fundamental coupling underlying the interactions of quarks and gluons in Quantum Chromodynamics (QCD). The dependence of αs(Q2) on momentum transfer Q encodes the underlying dynamics of hadron physics-from color confinement in the infrared domain to asymptotic freedom at short distances. We review constraints on αs(Q2) at high Q2, as predicted by perturbative QCD, and its analytic behavior at small Q2, based on models of nonperturbative dynamics. In the introductory part of this review, we explain the phenomenological meaning of the coupling, the reason for its running, and the challenges facing a complete understanding of its analytic behavior in the infrared domain. In the second, more technical, part of the review, we discuss the behavior of αs(Q2) in the high momentum transfer domain of QCD. We review how αs is defined, including its renormalization scheme dependence, the definition of its renormalization scale, the utility of effective charges, as well as "Commensurate Scale Relations" which connect the various definitions of the QCD coupling without renormalization-scale ambiguity. We also report recent significant measurements and advanced theoretical analyses which have led to precise QCD predictions at high energy. As an example of an important optimization procedure, we discuss the "Principle of Maximum Conformality", which enhances QCD's predictive power by removing the dependence of the predictions for physical observables on the choice of theoretical conventions such as the renormalization scheme. In the last part of the review, we discuss the challenge of understanding the analytic behavior αs(Q2) in the low momentum transfer domain. We survey various theoretical models for the nonperturbative strongly coupled regime, such as the light-front holographic approach to QCD. This new framework predicts the form of the quark-confinement potential underlying hadron spectroscopy and

  4. QCD (&) event generators

    SciTech Connect

    Skands, Peter Z.; /Fermilab

    2005-07-01

    Recent developments in QCD phenomenology have spurred on several improved approaches to Monte Carlo event generation, relative to the post-LEP state of the art. In this brief review, the emphasis is placed on approaches for (1) consistently merging fixed-order matrix element calculations with parton shower descriptions of QCD radiation, (2) improving the parton shower algorithms themselves, and (3) improving the description of the underlying event in hadron collisions.

  5. Radiative capture versus Coulomb dissociation.

    SciTech Connect

    Esbensen, H.; Physics

    2006-01-01

    Measurements of the Coulomb dissociation of {sup 8}B have been used to infer the rate of the inverse radiative proton capture on {sup 7}Be. The analysis is usually based on the assumptions that the two processes are related by detailed balance and described by E1 transitions. However, there are corrections to this relation. The Coulomb form factors for the two processes, for example, are not identical. There are also E2 transitions and higher-order effects in the Coulomb dissociation, and the nuclear induced breakup cannot always be ignored. While adding first-order E2 transitions enhances the decay energy spectrum, the other mechanisms cause a suppression at low relative energies. The net result may accidentally be close to the conventional first-order E1 calculation, but there are differences which cannot be ignored if accuracies of 10% or better are needed.

  6. Above-threshold ionization with highly charged ions in superstrong laser fields. I. Coulomb-corrected strong-field approximation

    NASA Astrophysics Data System (ADS)

    Klaiber, Michael; Yakaboylu, Enderalp; Hatsagortsyan, Karen Z.

    2013-02-01

    Aiming at the investigation of above-threshold ionization in superstrong laser fields with highly charged ions, we develop a Coulomb-corrected strong-field approximation (SFA). The influence of the Coulomb potential of the atomic core on the ionized electron dynamics in the continuum is taken into account via the eikonal approximation, treating the Coulomb potential perturbatively in the phase of the quasiclassical wave function of the continuum electron. In this paper the formalism of the Coulomb-corrected SFA for the nonrelativistic regime is discussed, employing velocity and length gauge. Direct ionization of a hydrogenlike system in a strong linearly polarized laser field is considered. The relation of the results in the different gauges to the Perelomov-Popov-Terent'ev imaginary-time method is discussed.

  7. Coulomb interactions in particle beams

    SciTech Connect

    Jansen, G.H. )

    1990-01-01

    This book develops analytical and computer models for beams in which Coulomb interactions are important. The research into the different phenomena of Coulomb interactions in particle beams is stimulated by developments in the field of electron beam lithography for VLSI electronics. The standard theory of charged particle optics breaks down for intense beams in which interactions between particles are significant. This monograph is devoted to the theory of these intense beams, which are not only used in VLSI electronics but also in scanning electron microscopes. The theory is also applicable to focused ion beams, which are used in VLSI mask repair.

  8. Maximal Abelian and Curci-Ferrari gauges in momentum subtraction at three loops

    NASA Astrophysics Data System (ADS)

    Bell, J. M.; Gracey, J. A.

    2015-12-01

    The vertex structure of QCD fixed in the maximal Abelian gauge (MAG) and Curci-Ferrari gauge is analyzed at two loops at the fully symmetric point for the 3-point functions corresponding to the three momentum subtraction (MOM) renormalization schemes. Consequently, the three-loop renormalization group functions are determined for each of these three schemes in each gauge using properties of the renormalization group equation.

  9. Motivations for AdS/QCD from 10D supergravity solutions.

    NASA Astrophysics Data System (ADS)

    de Paula, Wayne

    2016-04-01

    We discuss some attempts for the construction of gravity duals of QCD-like theories. It is analysed some properties of solutions of 10D Type IIB supergravity theory that attempt to be dual to N=1 gauge theories, in particular the solutions that belong to Papadoulos-Tseytlin ansatz. We argue that one could obtain 5D effective theories from 10d solutions and it motivates the use of phenomenological AdS/QCD models.

  10. Generalizing twisted gauge invariance

    SciTech Connect

    Duenas-Vidal, Alvaro; Vazquez-Mozo, Miguel A.

    2009-05-01

    We discuss the twisting of gauge symmetry in noncommutative gauge theories and show how this can be generalized to a whole continuous family of twisted gauge invariances. The physical relevance of these twisted invariances is discussed.

  11. Full CKM matrix with lattice QCD

    SciTech Connect

    Okamoto, Masataka; /Fermilab

    2004-12-01

    The authors show that it is now possible to fully determine the CKM matrix, for the first time, using lattice QCD. |V{sub cd}|, |V{sub cs}|, |V{sub ub}|, |V{sub cb}| and |V{sub us}| are, respectively, directly determined with the lattice results for form factors of semileptonic D {yields} {pi}lv, D {yields} Klv, B {yields} {pi}lv, B {yields} Dlv and K {yields} {pi}lv decays. The error from the quenched approximation is removed by using the MILC unquenced lattice gauge configurations, where the effect of u, d and s quarks is included. The error from the ''chiral'' extrapolation (m{sub l} {yields} m{sub ud}) is greatly reduced by using improved staggered quarks. The accuracy is comparable to that of the Particle Data Group averages. In addition, |V{sub ud}|, |V{sub ts}|, |V{sub ts}| and |V{sub td}| are determined by using unitarity of the CKM matrix and the experimental result for sin (2{beta}). In this way, they obtain all 9 CKM matrix elements, where the only theoretical input is lattice QCD. They also obtain all the Wolfenstein parameters, for the first time, using lattice QCD.

  12. Applications of Light-Front QCD

    SciTech Connect

    Brodsky, S

    2004-08-04

    Light-front Fock state wavefunctions encode the bound state properties of hadrons in terms of their quark and gluon degrees of freedom at the amplitude level. The freedom to choose the light-like quantization four-vector provides an explicitly covariant formulation of light-front quantization and can be used to determine the analytic structure of light-front wave functions. The AdS/CFT correspondence of large N{sub C} supergravity theory in higher-dimensional anti-de Sitter space with supersymmetric QCD in 4-dimensional space-time has interesting implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for exclusive processes. String/gauge duality also predicts the QCD power-law behavior of light-front Fock-state hadronic wavefunctions with arbitrary orbital angular momentum at high momentum transfer. The form of these near-conformal wavefunctions can be used as an initial ansatz for a variational treatment of the light-front QCD Hamiltonian. I also briefly review recent work which shows that some leading-twist phenomena such as the diffractive component of deep inelastic scattering, single spin asymmetries, nuclear shadowing and antishadowing cannot be computed from the LFWFs of hadrons in isolation.

  13. QCD in heavy quark production and decay

    SciTech Connect

    Wiss, J.

    1997-06-01

    The author discusses how QCD is used to understand the physics of heavy quark production and decay dynamics. His discussion of production dynamics primarily concentrates on charm photoproduction data which are compared to perturbative QCD calculations which incorporate fragmentation effects. He begins his discussion of heavy quark decay by reviewing data on charm and beauty lifetimes. Present data on fully leptonic and semileptonic charm decay are then reviewed. Measurements of the hadronic weak current form factors are compared to the nonperturbative QCD-based predictions of Lattice Gauge Theories. He next discusses polarization phenomena present in charmed baryon decay. Heavy Quark Effective Theory predicts that the daughter baryon will recoil from the charmed parent with nearly 100% left-handed polarization, which is in excellent agreement with present data. He concludes by discussing nonleptonic charm decay which is traditionally analyzed in a factorization framework applicable to two-body and quasi-two-body nonleptonic decays. This discussion emphasizes the important role of final state interactions in influencing both the observed decay width of various two-body final states as well as modifying the interference between interfering resonance channels which contribute to specific multibody decays. 50 refs., 77 figs.

  14. Color-kinematics duality for QCD amplitudes

    NASA Astrophysics Data System (ADS)

    Johansson, Henrik; Ochirov, Alexander

    2016-01-01

    We show that color-kinematics duality is present in tree-level amplitudes of quantum chromodynamics with massive flavored quarks. Starting with the color structure of QCD, we work out a new color decomposition for n-point tree amplitudes in a reduced basis of primitive amplitudes. These primitives, with k quark-antiquark pairs and ( n - 2 k) gluons, are taken in the ( n - 2)! /k! Melia basis, and are independent under the color-algebra Kleiss-Kuijf relations. This generalizes the color decomposition of Del Duca, Dixon, and Maltoni to an arbitrary number of quarks. The color coefficients in the new decomposition are given by compact expressions valid for arbitrary gauge group and representation. Considering the kinematic structure, we show through explicit calculations that color-kinematics duality holds for amplitudes with general configurations of gluons and massive quarks. The new (massive) amplitude relations that follow from the duality can be mapped to a well-defined subset of the familiar BCJ relations for gluons. They restrict the amplitude basis further down to ( n - 3)!(2 k - 2) /k! primitives, for two or more quark lines. We give a decomposition of the full amplitude in that basis. The presented results provide strong evidence that QCD obeys the color-kinematics duality, at least at tree level. The results are also applicable to supersymmetric and D-dimensional extensions of QCD.

  15. Schwinger effect for non-Abelian gauge bosons

    NASA Astrophysics Data System (ADS)

    Ragsdale, Michael; Singleton, Douglas

    2017-08-01

    We investigate the Schwinger effect for the gauge bosons in an unbroken non-Abelian gauge theory (e.g. the gluons of QCD). We consider both constant “color electric” fields and “color magnetic” fields as backgrounds. As in the Abelian Schwinger effect we find there is production of “gluons” for the color electric field, but no particle production for the color magnetic field case. Since the non-Abelian gauge bosons are massless there is no exponential suppression of particle production due to the mass of the electron/positron that one finds in the Abelian Schwinger effect. Despite the lack of an exponential suppression of the gluon production rate due to the masslessness of the gluons, we find that the critical field strength is even larger in the non-Abelian case as compared to the Abelian case. This is the result of the confinement phenomenon on QCD.

  16. Two loop QCD vertices at the symmetric point

    SciTech Connect

    Gracey, J. A.

    2011-10-15

    We compute the triple gluon, quark-gluon and ghost-gluon vertices of QCD at the symmetric subtraction point at two loops in the MS scheme. In addition we renormalize each of the three vertices in their respective momentum subtraction schemes, MOMggg, MOMq and MOMh. The conversion functions of all the wave functions, coupling constant and gauge parameter renormalization constants of each of the schemes relative to MS are determined analytically. These are then used to derive the three loop anomalous dimensions of the gluon, quark, Faddeev-Popov ghost and gauge parameter as well as the {beta} function in an arbitrary linear covariant gauge for each MOM scheme. There is good agreement of the latter with earlier Landau gauge numerical estimates of Chetyrkin and Seidensticker.

  17. Holographic study of the QCD matter under external conditions

    NASA Astrophysics Data System (ADS)

    Katanaeva, Alisa; Afonin, Sergey

    2017-03-01

    Holographic QCD is based on the AdS/CFT duality and offers new nonperturbative approaches to understand the strongly interacting regime of gauge theories. One of the primary questions in Quantum Chromodynamics is the clarification of the whole phase diagram of matter out of quarks and gluons as a function of temperature, baryon or quark chemical potential, and other external parameters. We use methods of the bottom-up AdS/QCD approach to bring out the phase structure of several holographic models in which transition to a deconfined phase is related to a (first order) Hawking-Page phase transition. The impact of phenomenological model parameters on the critical temperature and chemical potential is studied in detail. Comparison of the model predictions with results of experimental investigations, lattice QCD simulations and other methods is also done.

  18. TDA and RPA pseudoscalar and vector solutions for the low energy regime of a motivated QCD Hamiltonian.

    NASA Astrophysics Data System (ADS)

    Yépez-Martínez, T.; Amor Quiroz, D. A.; Hess, P. O.; Civitarese, O.

    2017-07-01

    We present the low energy meson spectrum of a Coulomb gauge QCD motivated Hamiltonian for light and strange quarks. We have used the harmonic oscillator as a trial basis and performed a pre-diagonalization of the kinetic energy term in order to get an effective basis where quark and anti-quark degrees of freedom are defined. For the relevant interactions between quarks and anti-quarks, we have implemented a confining interaction between color sources, in order to account in an effective way for the gluonic degrees of freedom. The low energy meson spectrum is obtained from the implementation of the TDA and RPA many-body-methods. The physical states have been described as TDA and RPA collective states with a relatively good agreement. Particularly, the particle-hole correlations of the RPA ground state improve the RPA pion-like state (159.7 MeV) close to its physical value while the TDA one remains at a higher energy (269.2 MeV).

  19. FOREWORD: Extreme QCD 2012 (xQCD)

    NASA Astrophysics Data System (ADS)

    Alexandru, Andrei; Bazavov, Alexei; Liu, Keh-Fei

    2013-04-01

    The Extreme QCD 2012 conference, held at the George Washington University in August 2012, celebrated the 10th event in the series. It has been held annually since 2003 at different locations: San Carlos (2011), Bad Honnef (2010), Seoul (2009), Raleigh (2008), Rome (2007), Brookhaven (2006), Swansea (2005), Argonne (2004), and Nara (2003). As usual, it was a very productive and inspiring meeting that brought together experts in the field of finite-temperature QCD, both theoretical and experimental. On the experimental side, we heard about recent results from major experiments, such as PHENIX and STAR at Brookhaven National Laboratory, ALICE and CMS at CERN, and also about the constraints on the QCD phase diagram coming from astronomical observations of one of the largest laboratories one can imagine, neutron stars. The theoretical contributions covered a wide range of topics, including QCD thermodynamics at zero and finite chemical potential, new ideas to overcome the sign problem in the latter case, fluctuations of conserved charges and how they allow one to connect calculations in lattice QCD with experimentally measured quantities, finite-temperature behavior of theories with many flavors of fermions, properties and the fate of heavy quarkonium states in the quark-gluon plasma, and many others. The participants took the time to write up and revise their contributions and submit them for publication in these proceedings. Thanks to their efforts, we have now a good record of the ideas presented and discussed during the workshop. We hope that this will serve both as a reminder and as a reference for the participants and for other researchers interested in the physics of nuclear matter at high temperatures and density. To preserve the atmosphere of the event the contributions are ordered in the same way as the talks at the conference. We are honored to have helped organize the 10th meeting in this series, a milestone that reflects the lasting interest in this

  20. Comparative Study of Algorithms for the Numerical Simulation of Lattice QCD

    SciTech Connect

    Luz, Fernando H. P.; Mendes, Tereza

    2010-11-12

    Large-scale numerical simulations are the prime method for a nonperturbative study of QCD from first principles. Although the lattice simulation of the pure-gauge (or quenched-QCD) case may be performed very efficiently on parallel machines, there are several additional difficulties in the simulation of the full-QCD case, i.e. when dynamical quark effects are taken into account. We discuss the main aspects of full-QCD simulations, describing the most common algorithms. We present a comparative analysis of performance for two versions of the hybrid Monte Carlo method (the so-called R and RHMC algorithms), as provided in the MILC software package. We consider two degenerate flavors of light quarks in the staggered formulation, having in mind the case of finite-temperature QCD.

  1. Lattice QCD calculation of the {rho} meson decay width

    SciTech Connect

    Aoki, S.; Fukugita, M.; Ishikawa, K-I.; Okawa, M.; Ishizuka, N.; Kuramashi, Y.; Ukawa, A.; Yoshie, T.; Kanaya, K.; Namekawa, Y.; Sasaki, K.

    2007-11-01

    We present a lattice QCD calculation of the {rho} meson decay width via the P-wave scattering phase shift for the I=1 two-pion system. Our calculation uses full QCD gauge configurations for N{sub f}=2 flavors generated using a renormalization group improved gauge action and an improved Wilson fermion action on a 12{sup 3}x24 lattice at m{sub {pi}}/m{sub {rho}}=0.41 and the lattice spacing 1/a=0.92 GeV. The phase shift calculated with the use of the finite size formula for the two-pion system in the moving frame shows a behavior consistent with the existence of a resonance at a mass close to the vector meson mass obtained in spectroscopy. The decay width estimated from the phase shift is consistent with the experiment, when the quark mass is scaled to the realistic value.

  2. Cosmologically Safe QCD Axion without Fine-Tuning

    NASA Astrophysics Data System (ADS)

    Yamada, Masaki; Yanagida, Tsutomu T.; Yonekura, Kazuya

    2016-02-01

    Although QCD axion models are widely studied as solutions to the strong C P problem, they generically confront severe fine-tuning problems to guarantee the anomalous Peccei-Quinn (PQ) symmetry. In this Letter, we propose a simple QCD axion model without any fine-tunings. We introduce an extra dimension and a pair of extra quarks living on two branes separately, which is also charged under a bulk Abelian gauge symmetry. We assume a monopole condensation on our brane at an intermediate scale, which implies that the extra quarks develop chiral symmetry breaking and the PQ symmetry is broken. In contrast to Kim's original model, our model explains the origin of the PQ symmetry thanks to the extra dimension and avoids the cosmological domain wall problem because of chiral symmetry breaking in Abelian gauge theory.

  3. Cosmologically Safe QCD Axion without Fine-Tuning.

    PubMed

    Yamada, Masaki; Yanagida, Tsutomu T; Yonekura, Kazuya

    2016-02-05

    Although QCD axion models are widely studied as solutions to the strong CP problem, they generically confront severe fine-tuning problems to guarantee the anomalous Peccei-Quinn (PQ) symmetry. In this Letter, we propose a simple QCD axion model without any fine-tunings. We introduce an extra dimension and a pair of extra quarks living on two branes separately, which is also charged under a bulk Abelian gauge symmetry. We assume a monopole condensation on our brane at an intermediate scale, which implies that the extra quarks develop chiral symmetry breaking and the PQ symmetry is broken. In contrast to Kim's original model, our model explains the origin of the PQ symmetry thanks to the extra dimension and avoids the cosmological domain wall problem because of chiral symmetry breaking in Abelian gauge theory.

  4. Local Momenta and a Three-Body Gauge

    NASA Astrophysics Data System (ADS)

    Schillaci, Michael

    2001-05-01

    In recent years researchers have attempted to improve the continuum state three-body wavefunction for three, mutually interacting Coulomb particles by including, so called, phlocal momentum effects, which depend upon the logarithmic gradient of continuum, two-body Coulomb waves. Numerical calculations confirm that while ignoring these local effects for phlight-ion--atom processes, may be appropriate, three-body effects may dominate in the reaction zone for phheavy-ion--atom processes. Preliminary calculations show a deviation of less than 10% between the predicted and observed asymmetries in the data collected by Wiese, phet. al.,[ PRL 79, 4982] on the correlated breakup of three massive, Coulomb interacting particles. While treating the local momenta as a formal gauge constraint for three-body interactions, it is shown that a real-valued, position-dependent phase is added to the wavefunction and may be detectable in continued studies of massive Coulomb systems.

  5. Running coupling constant of ten-flavor QCD with the Schroedinger functional method

    SciTech Connect

    Hayakawa, M.; Uno, S.; Ishikawa, K.-I.; Osaki, Y.; Takeda, S.; Yamada, N.

    2011-04-01

    The walking technicolor theory attempts to realize electroweak symmetry breaking as the spontaneous chiral symmetry breakdown caused by the gauge dynamics with slowly varying gauge coupling constant and large mass anomalous dimension. Many-flavor QCD theories are candidates owning these features. We focus on the SU(3) gauge theory with ten flavors of massless fermions in the fundamental representation, and compute the gauge coupling constant in the Schroedinger functional scheme. Numerical simulation is performed with O(a)-unimproved lattice action, and the continuum limit is taken in linear in lattice spacing. We observe evidence that this theory possesses an infrared fixed point.

  6. Perfect Abelian dominance of confinement in mesons and baryons in SU(3) lattice QCD

    NASA Astrophysics Data System (ADS)

    Sakumichi, Naoyuki; Suganuma, Hideo

    2016-11-01

    For a long time, the quark confinement mechanism has been one of the most difficult problems in theoretical physics. In particular, there is no clear correspondence between the confinement and non-Abelian nature of QCD. We study the static interquark potential and its Abelian projection in both mesons and baryons in the maximally Abelian (MA) gauge in SU(3) quenched lattice QCD. Remarkably, we find that the quark confining force in QCD can be perfectly described only with Abelian variables in theMAgauge, which we call "perfect Abelian dominance" of the quark confinement.

  7. Lattice QCD solution to the U(1) problem

    SciTech Connect

    Fukugita, M. ); Kuramashi, Y.; Okawa, M. , Tsukuba, Ibaraki 305 ); Ukawa, A. )

    1995-04-01

    It is shown in quenched lattice QCD that the mass splitting between [eta][prime] and a pion arises from gauge configurations with a nonzero topological charge [ital Q], its magnitude increasing for larger values of [vert bar][ital Q][vert bar]; the contribution from the disconnected quark loop is strongly hindered unless the topological charge is excited. This demonstrates the explicit relation between the large [eta][prime] meson mass and gauge field topology, which is in the line of the argument in the continuum of instantons and the 1/[ital N] expansion.

  8. Coulomb interaction in multiple scattering theory

    NASA Astrophysics Data System (ADS)

    Ray, L.; Hoffmann, G. W.; Thaler, R. M.

    1980-10-01

    The treatment of the Coulomb interaction in the multiple scattering theories of Kerman-McManus-Thaler and Watson is examined in detail. By neglecting virtual Coulomb excitations, the lowest order Coulomb term in the Watson optical potential is shown to be a convolution of the point Coulomb interaction with the distributed nuclear charge, while the equivalent Kerman-McManus-Thaler Coulomb potential is obtained from an averaged, single-particle Coulombic T matrix. The Kerman-McManus-Thaler Coulomb potential is expressed as the Watson Coulomb term plus additional Coulomb-nuclear and Coulomb-Coulomb cross terms, and the omission of the extra terms in usual Kerman-McManus-Thaler applications leads to negative infinite total reaction cross section predictions and incorrect pure Coulomb scattering limits. Approximations are presented which eliminate these anomalies. Using the two-potential formula, the full projectile-nucleus T matrix is separated into two terms, one resulting from the distributed nuclear charge and the other being a Coulomb distorted nuclear T matrix. It is shown that the error resulting from the omission of the Kerman-McManus-Thaler Coulomb terms is effectively removed when the pure Coulomb T matrix in Kerman-McManus-Thaler is replaced by the analogous quantity in the Watson approach. Using the various approximations, theoretical angular distributions are obtained for 800 MeV p+208Pb elastic scattering and compared with experimental data. NUCLEAR REACTIONS 208Pb(p, p), E=0.8 GeV, Kerman, McManus, and Thaler, and Watson multiple scattering theories, Coulomb correction terms, high momentum transfer.

  9. Unified models of the QCD axion and supersymmetry breaking

    NASA Astrophysics Data System (ADS)

    Harigaya, Keisuke; Leedom, Jacob M.

    2017-08-01

    Similarities between the gauge meditation of supersymmetry breaking and the QCD axion model suggest that they originate from the same dynamics. We present a class of models where supersymmetry and the Peccei-Quinn symmetry are simultaneously broken. The messengers that mediate the effects of these symmetry breakings to the Standard Model are identical. Since the axion resides in the supersymmetry breaking sector, the saxion and the axino are heavy. We show constraints on the axion decay constant and the gravitino mass.

  10. Semileptonic decays of D mesons in unquenched lattice QCD

    SciTech Connect

    Masataka Okamoto et al.

    2004-03-17

    We present our preliminary results for semileptonic form factors of D mesons in unquenched lattice QCD. Simulations are carried out with n{sub f} = 2 + 1 dynamical quarks using gauge configurations generated by the MILC collaboration. For the valence quarks, we adopt an improved staggered light quark action and the clover heavy quark action. Our results for D {yields} K and D {yields} {pi} form factors at q{sup 2} = 0 are in agreement with the experimental values.

  11. Transverse momentum dependent quark densities from Lattice QCD

    SciTech Connect

    Bernhard Musch,Philipp Hagler,John Negele,Andreas Schafer

    2011-02-01

    We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. Results obtained with a simpli?ed operator geometry show visible dipole de- formations of spin-dependent quark momentum densities. We discuss the basic concepts of the method, including renormalization of the gauge link, and an ex- tension to a more elaborate operator geometry that would allow us to analyze process-dependent TMDs such as the Sivers-function.

  12. Transverse momentum distributions inside the nucleon from Lattice QCD

    SciTech Connect

    Bernhard Musch, Philipp Hagler, John Negele, Andreas Schafer

    2010-06-01

    We study transverse momentum dependent parton distribution functions (TMDs) with non-local operators in lattice QCD, using MILC/LHPC lattices. Results obtained with a simplified operator geometry show visible dipole deformations of spin-dependent quark momentum densities. We discuss the basic concepts of the method, including renormalization of the gauge link, and an extension to a more elaborate operator geometry that would allow us to analyze process-dependent TMDs such as the Sivers-function.

  13. R evolution: Improving perturbative QCD

    SciTech Connect

    Hoang, Andre H.; Jain, Ambar; Stewart, Iain W.; Scimemi, Ignazio

    2010-07-01

    Perturbative QCD results in the MS scheme can be dramatically improved by switching to a scheme that accounts for the dominant power law dependence on the factorization scale in the operator product expansion. We introduce the ''MSR scheme'' which achieves this in a Lorentz and gauge invariant way and has a very simple relation to MS. Results in MSR depend on a cutoff parameter R, in addition to the {mu} of MS. R variations can be used to independently estimate (i.) the size of power corrections, and (ii.) higher-order perturbative corrections (much like {mu} in MS). We give two examples at three-loop order, the ratio of mass splittings in the B*-B and D*-D systems, and the Ellis-Jaffe sum rule as a function of momentum transfer Q in deep inelastic scattering. Comparing to data, the perturbative MSR results work well even for Q{approx}1 GeV, and power corrections are reduced compared to MS.

  14. QCD Evolution 2015

    NASA Astrophysics Data System (ADS)

    These are the proceedings of the QCD Evolution 2015 Workshop which was held 26-30 May, 2015 at Jefferson Lab, Newport News, Virginia, USA. The workshop is a continuation of a series of workshops held during four consecutive years 2011, 2012, 2013 at Jefferson Lab, and in 2014 in Santa Fe, NM. With the rapid developments in our understanding of the evolution of parton distributions including low-x, TMDs, GPDs, higher-twist correlation functions, and the associated progress in perturbative QCD, lattice QCD and effective field theory techniques we look forward with great enthusiasm to the 2015 meeting. A special attention was also paid to participation of experimentalists as the topics discussed are of immediate importance for the JLab 12 experimental program and a future Electron Ion Collider.

  15. Ionization in an intense field considering Coulomb correction

    NASA Astrophysics Data System (ADS)

    Li, Jian; Huo, Yi-Ning; Tang, Zeng-Hua; Ma, Feng-Cai

    2017-01-01

    We derive a simple ionization rate formula for the ground state of a hydrogen atom in the velocity gauge under the conditions: ω \\ll 1 a.u. (a.u. is short for atomic unit) and γ \\ll 1 (ω is the laser frequency and γ is the Keldysh parameter). Comparisons are made among the different versions of the Keldysh–Faisal–Reiss (KFR) theory. The numerical study shows that with considering the quasi-classical (WKB) Coulomb correction in the final state of the ionized electron, the photoionization rate is enhanced compared with without considering the Coulomb correction, and the Reiss theory with the WKB Coulomb correction gives the correct result in the tunneling regime. Our concise formula of the ionization rate may provide an insight into the ionization mechanism for the ground state of a hydrogen atom. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274149 and 11304185) and the Program of Shenyang Key Laboratory of Optoelectronic Materials and Technology, China (Grant No. F12-254-1-00).

  16. Gauge theories in anti-selfdual variables

    NASA Astrophysics Data System (ADS)

    Bochicchio, Marco; Pilloni, Alessandro

    2013-09-01

    Some years ago the Nicolai map, viewed as a change of variables from the gauge connection in a fixed gauge to the anti-selfdual part of the curvature, has been extended by the first named author to pure Yang-Mills from its original definition in = 1 supersymmetric Yang-Mills. We study here the perturbative one-particle irreducible effective action in the anti-selfdual variables of any gauge theory, in particular pure Yang-Mills, QCD and = 1 supersymmetric Yang-Mills. We prove that the one-loop one-particle irreducible effective action of a gauge theory mapped to the anti-selfdual variables in any gauge is identical to the one of the original theory. This is due to the conspiracy between the Jacobian of the change to the anti-selfdual variables and an extra functional determinant that arises from the non-linearity of the coupling of the anti-selfdual curvature to an external source in the Legendre transform that defines the one-particle irreducible effective action. Hence we establish the one-loop perturbative equivalence of the mapped and original theories on the basis of the identity of the one-loop one-particle irreducible effective actions. Besides, we argue that the identity of the perturbative one-particle irreducible effective actions extends order by order in perturbation theory.

  17. Coulomb dissociation of N,2120

    NASA Astrophysics Data System (ADS)

    Röder, Marko; Adachi, Tatsuya; Aksyutina, Yulia; Alcantara, Juan; Altstadt, Sebastian; Alvarez-Pol, Hector; Ashwood, Nicholas; Atar, Leyla; Aumann, Thomas; Avdeichikov, Vladimir; Barr, M.; Beceiro, Saul; Bemmerer, Daniel; Benlliure, Jose; Bertulani, Carlos; Boretzky, Konstanze; Borge, Maria J. G.; Burgunder, G.; Caamaño, Manuel; Caesar, Christoph; Casarejos, Enrique; Catford, Wilton; Cederkäll, Joakim; Chakraborty, S.; Chartier, Marielle; Chulkov, Leonid; Cortina-Gil, Dolores; Crespo, Raquel; Datta Pramanik, Ushasi; Diaz-Fernandez, Paloma; Dillmann, Iris; Elekes, Zoltan; Enders, Joachim; Ershova, Olga; Estrade, A.; Farinon, F.; Fraile, Luis M.; Freer, Martin; Freudenberger, M.; Fynbo, Hans; Galaviz, Daniel; Geissel, Hans; Gernhäuser, Roman; Göbel, Kathrin; Golubev, Pavel; Gonzalez Diaz, D.; Hagdahl, Julius; Heftrich, Tanja; Heil, Michael; Heine, Marcel; Heinz, Andreas; Henriques, Ana; Holl, Matthias; Ickert, G.; Ignatov, Alexander; Jakobsson, Bo; Johansson, Hâkan; Jonson, Björn; Kalantar-Nayestanaki, Nasser; Kanungo, Rituparna; Kelic-Heil, Aleksandra; Knöbel, Ronja; Kröll, Thorsten; Krücken, Reiner; Kurcewicz, J.; Kurz, Nikolaus; Labiche, Marc; Langer, Christoph; Le Bleis, Tudi; Lemmon, Roy; Lepyoshkina, Olga; Lindberg, Simon; Machado, Jorge; Marganiec, Justyna; Mostazo Caro, Magdalena; Movsesyan, Alina; Najafi, Mohammad Ali; Nilsson, Thomas; Nociforo, Chiara; Panin, Valerii; Paschalis, Stefanos; Perea, Angel; Petri, Marina; Pietri, S.; Plag, Ralf; Prochazka, A.; Rahaman, Md. Anisur; Rastrepina, Ganna; Reifarth, Rene; Ribeiro, Guillermo; Ricciardi, M. Valentina; Rigollet, Catherine; Riisager, Karsten; Rossi, Dominic; Sanchez del Rio Saez, Jose; Savran, Deniz; Scheit, Heiko; Simon, Haik; Sorlin, Olivier; Stoica, V.; Streicher, Branislav; Taylor, Jon; Tengblad, Olof; Terashima, Satoru; Thies, Ronja; Togano, Yasuhiro; Uberseder, Ethan; Van de Walle, J.; Velho, Paulo; Volkov, Vasily; Wagner, Andreas; Wamers, Felix; Weick, Helmut; Weigand, Mario; Wheldon, Carl; Wilson, G.; Wimmer, Christine; Winfield, J. S.; Woods, Philip; Yakorev, Dmitry; Zhukov, Mikhail; Zilges, Andreas; Zuber, Kai; R3B Collaboration

    2016-06-01

    Neutron-rich light nuclei and their reactions play an important role in the creation of chemical elements. Here, data from a Coulomb dissociation experiment on N,2120 are reported. Relativistic N,2120 ions impinged on a lead target and the Coulomb dissociation cross section was determined in a kinematically complete experiment. Using the detailed balance theorem, the 19N (n ,γ )20N and 20N (n ,γ ) 21N excitation functions and thermonuclear reaction rates have been determined. The 19 (n ,γ )20N rate is up to a factor of 5 higher at T <1 GK with respect to previous theoretical calculations, leading to a 10% decrease in the predicted fluorine abundance.

  18. Coulomb blockade in graphene nanoribbons.

    PubMed

    Sols, F; Guinea, F; Neto, A H

    2007-10-19

    We propose that recent transport experiments revealing the existence of an energy gap in graphene nanoribbons may be understood in terms of Coulomb blockade. Electron interactions play a decisive role at the quantum dots which form due to the presence of necks arising from the roughness of the graphene edge. With the average transmission as the only fitting parameter, our theory shows good agreement with the experimental data.

  19. Infrared features of unquenched finite temperature lattice Landau gauge QCD

    SciTech Connect

    Furui, Sadataka; Nakajima, Hideo

    2007-09-01

    The color diagonal and color antisymmetric ghost propagators slightly above T{sub c} of N{sub f}=2 MILC 24{sup 3}x12 lattices are measured and compared with zero-temperature unquenched N{sub f}=2+1 MILC{sub c} 20{sup 3}x64 and MILC{sub f} 28{sup 3}x96 lattices and zero-temperature quenched 56{sup 4} {beta}=6.4 and 6.45 lattices. The expectation value of the color antisymmetric ghost propagator {phi}{sup c}(q) is zero, but its Binder cumulant, which is consistent with that of N{sub c}{sup 2}-1 dimensional Gaussian distribution below T{sub c}, decreases above T{sub c}. Although the color diagonal ghost propagator is temperature independent, the l{sup 1} norm of the color antisymmetric ghost propagator is temperature dependent. The expectation value of the ghost condensate observed at zero-temperature unquenched configuration is consistent with 0 in T>T{sub c}. We also measure transverse, magnetic, and electric gluon propagator and extract gluon screening masses. The running coupling measured from the product of the gluon dressing function and the ghost dressing function are almost temperature independent, but the effect of A{sup 2} condensate observed at zero temperature is consistent with 0 in T>T{sub c}. The transverse gluon dressing function at low temperature has a peak in the infrared at low temperature, but it becomes flatter at high temperature. The magnetic gluon propagator at high momentum depends on the temperature. These data imply that the magnetic gluon propagator and the color antisymmetric ghost propagator are affected by the presence of dynamical quarks, and there are strong nonperturbative effects through the temperature-dependent color antisymmetric ghost propagator.

  20. Boson mapping techniques applied to constant gauge fields in QCD

    NASA Technical Reports Server (NTRS)

    Hess, Peter Otto; Lopez, J. C.

    1995-01-01

    Pairs of coordinates and derivatives of the constant gluon modes are mapped to new gluon-pair fields and their derivatives. Applying this mapping to the Hamiltonian of constant gluon fields results for large coupling constants into an effective Hamiltonian which separates into one describing a scalar field and another one for a field with spin two. The ground state is dominated by pairs of gluons coupled to color and spin zero with slight admixtures of color zero and spin two pairs. As color group we used SU(2).

  1. Ordering in classical Coulombic systems.

    SciTech Connect

    Schiffer, J. P.

    1998-01-22

    The author discusses the properties of classical Coulombic matter at low temperatures. It has been well known for some time [1,2] that infinite Coulombic matter will crystallize in body-centered cubic form when the quantity {Lambda} (the dimensionless ratio of the average two-particle Coulomb energy to the kinetic energy per particle) is larger than {approximately}175. But the systems of such particles that have been produced in the laboratory in ion traps, or ion beams, are finite with surfaces defined by the boundary conditions that have to be satisfied. This results in ion clouds with sharply defined curved surfaces, and interior structures that show up as a set of concentric layers that are parallel to the outer surface. The ordering does not appear to be cubic, but the charges on each shell exhibit a ''hexatic'' pattern of equilateral triangles that is the characteristic of liquid crystals. The curvature of the surfaces prevents the structures on successive shells from interlocking in any simple fashion. This class of structures was first found in simulations [3] and later in experiments [4].

  2. Problems with vector confinement in 4d QCD

    NASA Astrophysics Data System (ADS)

    Simonov, Yu. A.

    2017-07-01

    It is shown that vector confinement does not support bound state spectrum in the 4d Dirac equation. The same property is confirmed in the heavy-light and light-light QCD systems. This situation is compared with the confinement in the 2d system, which is generated by the gluon exchange. Considering the existing theories of confinement, it is shown that both the field correlator approach and the dual superconductor model ensure the scalar confinement in contrast to the Gribov-Zwanziger model, where the confning Coulomb potential does not support bound states in the Dirac equation..

  3. The phase structure of QCD

    NASA Astrophysics Data System (ADS)

    Schmidt, Christian; Sharma, Sayantan

    2017-10-01

    We review recent results on the phase structure of quantum chromodynamics (QCD) and bulk QCD thermodynamics. In particular, we discuss how universal critical scaling related to spontaneous breaking of the chiral symmetry manifests itself in recent lattice QCD simulations and how the knowledge on non-universal scaling parameters can be utilized in the exploration of the QCD phase diagram. We also show how various (generalized) susceptibilities can be employed to characterize properties of QCD matter at low and high temperatures, related to deconfining aspects of the QCD transition. Finally, we highlight the recent efforts towards understanding how lattice QCD calculation can provide input for our understanding of the matter created in heavy ion collisions and in particular on the freeze-out conditions met in the hydrodynamic evolution of this matter.

  4. PRELIMINARY RESULTS FROM A SIMULATION OF QUENCHED QCD WITH OVERL AP FERMIONS ON A LARGE LATTICE.

    SciTech Connect

    BERRUTO,F.GARRON,N.HOELBLING,D.LELLOUCH,L.REBBI,C.SHORESH,N.

    2003-07-15

    We simulate quenched QCD with the overlap Dirac operator. We work with the Wilson gauge action at {beta} = 6 on an 18{sup 3} x 64 lattice. We calculate quark propagators for a single source point and quark mass ranging from am{sub 4} = 0.03 to 0.75. We present here preliminary results based on the propagators for 60 gauge field configurations.

  5. Diagrammatic proof of the BCFW recursion relation for gluon amplitudes in QCD

    NASA Astrophysics Data System (ADS)

    Draggiotis, P. D.; Kleiss, R. H. P.; Lazopoulos, A.; Papadopoulos, C. G.

    2006-06-01

    We present a proof of the Britto Cachazo Feng Witten tree-level recursion relation for gluon amplitudes in QCD, based on a direct equivalence between BCFW decompositions and Feynman diagrams. We demonstrate that this equivalence can be made explicit when working in a convenient gauge. We exhibit that gauge invariance and the particular structure of Yang Mills vertices guarantee the validity of the BCFW construction.

  6. Baryons and QCD

    SciTech Connect

    Nathan Isgur

    1997-03-01

    The author presents an idiosyncratic view of baryons which calls for a marriage between quark-based and hadronic models of QCD. He advocates a treatment based on valence quark plus glue dominance of hadron structure, with the sea of q pairs (in the form of virtual hadron pairs) as important corrections.

  7. QCD: Quantum Chromodynamics

    ScienceCinema

    Lincoln, Don

    2016-07-12

    The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilab’s Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.

  8. QCD and Hadron Physics

    SciTech Connect

    Brodsky, Stanley J.; Deshpande, Abhay L.; Gao, Haiyan; McKeown, Robert D.; Meyer, Curtis A.; Meziani, Zein-Eddine; Milner, Richard G.; Qiu, Jianwei; Richards, David G.; Roberts, Craig D.

    2015-02-26

    This White Paper presents the recommendations and scientific conclusions from the Town Meeting on QCD and Hadronic Physics that took place in the period 13-15 September 2014 at Temple University as part of the NSAC 2014 Long Range Planning process. The meeting was held in coordination with the Town Meeting on Phases of QCD and included a full day of joint plenary sessions of the two meetings. The goals of the meeting were to report and highlight progress in hadron physics in the seven years since the 2007 Long Range Plan (LRP07), and present a vision for the future by identifying the key questions and plausible paths to solutions which should define the next decade. The introductory summary details the recommendations and their supporting rationales, as determined at the Town Meeting on QCD and Hadron Physics, and the endorsements that were voted upon. The larger document is organized as follows. Section 2 highlights major progress since the 2007 LRP. It is followed, in Section 3, by a brief overview of the physics program planned for the immediate future. Finally, Section 4 provides an overview of the physics motivations and goals associated with the next QCD frontier: the Electron-Ion-Collider.

  9. Hadronic laws from QCD

    NASA Astrophysics Data System (ADS)

    Cahill, R. T.

    1992-06-01

    A review is given of progress in deriving the effective action for hadronic physics, S[π, ϱ, ω,.., overlineN, N,..] , from the fundamental defining action of QCD, S[ overlineq, q, A μa] . This is a problem in quantum field theory and the most success so far has been achieved using functional integral calculus (FIC) techniques. This formulates the problem as an exercise in changing the variables of integration in the functional integrals, from those of the quark and gluon fields to those of the (bare) meson and baryon fields. The appropriate variables are determined by the dynamics of QCD, and the final hadronic variables (essentially the 'normal modes' of QCD) are local fields describing the 'centre-of-mass' motion of extended bound states of quarks. The quarks are extensively dressed by the gluons, and the detailed aspects of the hidden chiral symmetry emerge naturally from the formalism. Particular attention is given to covariant integral equations which determine bare nucleon structure (i.e. in the quenched approximation). These equations, which arise from the closed double-helix diagrams of the FIC analysis, describe the baryons in terms of quark-diquark structure, in the form of Faddeev equations. This hadronisation of QCD also generates the dressing of these baryons by the pions, and the non-local πNN coupling.

  10. REGGE TRAJECTORIES IN QCD

    SciTech Connect

    Radyushkin, Anatoly V.; Efremov, Anatoly Vasilievich; Ginzburg, Ilya F.

    2013-04-01

    We discuss some problems concerning the application of perturbative QCD to high energy soft processes. We show that summing the contributions of the lowest twist operators for non-singlet $t$-channel leads to a Regge-like amplitude. Singlet case is also discussed.

  11. QCD results from CDF

    SciTech Connect

    Plunkett, R.; The CDF Collaboration

    1991-10-01

    Results are presented for hadronic jet and direct photon production at {radical}{bar s} = 1800 GeV. The data are compared with next-to-leading QCD calculations. A new limit on the scale of possible composite structure of the quarks is also reported. 12 refs., 4 figs.

  12. QCD physics at CDF

    SciTech Connect

    Devlin, T.; CDF Collaboration

    1996-10-01

    The CDF collaboration is engaged in a broad program of QCD measurements at the Fermilab Tevatron Collider. I will discuss inclusive jet production at center-of-mass energies of 1800 GeV and 630 GeV, properties of events with very high total transverse energy and dijet angular distributions.

  13. Progress in lattice QCD

    SciTech Connect

    Andreas S. Kronfeld

    2002-09-30

    After reviewing some of the mathematical foundations and numerical difficulties facing lattice QCD, I review the status of several calculations relevant to experimental high-energy physics. The topics considered are moments of structure functions, which may prove relevant to search for new phenomena at the LHC, and several aspects of flavor physics, which are relevant to understanding CP and flavor violation.

  14. QCD: Quantum Chromodynamics

    SciTech Connect

    Lincoln, Don

    2016-06-17

    The strongest force in the universe is the strong nuclear force and it governs the behavior of quarks and gluons inside protons and neutrons. The name of the theory that governs this force is quantum chromodynamics, or QCD. In this video, Fermilab’s Dr. Don Lincoln explains the intricacies of this dominant component of the Standard Model.

  15. Phenomenology Using Lattice QCD

    NASA Astrophysics Data System (ADS)

    Gupta, R.

    2005-08-01

    This talk provides a brief summary of the status of lattice QCD calculations of the light quark masses and the kaon bag parameter BK. Precise estimates of these four fundamental parameters of the standard model, i.e., mu, md, ms and the CP violating parameter η, help constrain grand unified models and could provide a window to new physics.

  16. Phenomenology Using Lattice QCD

    NASA Astrophysics Data System (ADS)

    Gupta, R.

    This talk provides a brief summary of the status of lattice QCD calculations of the light quark masses and the kaon bag parameter BK. Precise estimates of these four fundamental parameters of the standard model, i.e., mu, md, ms and the CP violating parameter η, help constrain grand unified models and could provide a window to new physics.

  17. Quantum Gauge Symmetry of Reducible Gauge Theory

    NASA Astrophysics Data System (ADS)

    Dwivedi, Manoj Kumar

    2017-05-01

    We derive the gaugeon formalism of the Kalb-Ramond field theory, a reducible gauge theory, which discusses the quantum gauge freedom. In gaugeon formalism, theory admits quantum gauge symmetry which leaves the action form-invariant. The BRST symmetric gaugeon formalism is also studied which introduces the gaugeon ghost fields and gaugeon ghosts of ghosts fields. To replace the Yokoyama subsidiary conditions by a single Kugo-Ojima type condition the virtue of BRST symmetry is utilized. Under generalized BRST transformations, we show that the gaugeon fields appear naturally in the reducible gauge theory.

  18. Conformal Aspects of QCD

    SciTech Connect

    Brodsky, S

    2003-11-19

    Theoretical and phenomenological evidence is now accumulating that the QCD coupling becomes constant at small virtuality; i.e., {alpha}{sub s}(Q{sup 2}) develops an infrared fixed point in contradiction to the usual assumption of singular growth in the infrared. For example, the hadronic decays of the {tau} lepton can be used to determine the effective charge {alpha}{sub {tau}}(m{sub {tau}{prime}}{sup 2}) for a hypothetical {tau}-lepton with mass in the range 0 < m{sub {tau}{prime}} < m{sub {tau}}. The {tau} decay data at low mass scales indicates that the effective charge freezes at a value of s = m{sub {tau}{prime}}{sup 2} of order 1 GeV{sup 2} with a magnitude {alpha}{sub {tau}} {approx} 0.9 {+-} 0.1. The near-constant behavior of effective couplings suggests that QCD can be approximated as a conformal theory even at relatively small momentum transfer and why there are no significant running coupling corrections to quark counting rules for exclusive processes. The AdS/CFT correspondence of large N{sub c} supergravity theory in higher-dimensional anti-de Sitter space with supersymmetric QCD in 4-dimensional space-time also has interesting implications for hadron phenomenology in the conformal limit, including an all-orders demonstration of counting rules for exclusive processes and light-front wavefunctions. The utility of light-front quantization and light-front Fock wavefunctions for analyzing nonperturbative QCD and representing the dynamics of QCD bound states is also discussed.

  19. Baryons in holographic QCD

    NASA Astrophysics Data System (ADS)

    Nawa, Kanabu; Suganuma, Hideo; Kojo, Toru

    2007-04-01

    We study baryons in holographic QCD with D4/D8/D8¯ multi-D-brane system. In holographic QCD, the baryon appears as a topologically nontrivial chiral soliton in a four-dimensional effective theory of mesons. We call this topological soliton brane-induced Skyrmion. Some review of D4/D8/D8¯ holographic QCD is presented from the viewpoints of recent hadron physics and QCD phenomenologies. A four-dimensional effective theory with pions and ρ mesons is uniquely derived from the non-Abelian Dirac-Born-Infeld (DBI) action of D8 brane with D4 supergravity background at the leading order of large Nc, without small amplitude expansion of meson fields to discuss chiral solitons. For the hedgehog configuration of pion and ρ-meson fields, we derive the energy functional and the Euler-Lagrange equation of brane-induced Skyrmion from the meson effective action induced by holographic QCD. Performing the numerical calculation, we obtain the soliton solution and figure out the pion profile F(r) and the ρ-meson profile G˜(r) of the brane-induced Skyrmion with its total energy, energy density distribution, and root-mean-square radius. These results are compared with the experimental quantities of baryons and also with the profiles of standard Skyrmion without ρ mesons. We analyze interaction terms of pions and ρ mesons in brane-induced Skyrmion, and find a significant ρ-meson component appearing in the core region of a baryon.

  20. Novel QCD Phenomenology

    SciTech Connect

    Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

    2011-08-12

    I review a number of topics where conventional wisdom in hadron physics has been challenged. For example, hadrons can be produced at large transverse momentum directly within a hard higher-twist QCD subprocess, rather than from jet fragmentation. Such 'direct' processes can explain the deviations from perturbative QCD predictions in measurements of inclusive hadron cross sections at fixed x{sub T} = 2p{sub T}/{radical}s, as well as the 'baryon anomaly', the anomalously large proton-to-pion ratio seen in high centrality heavy ion collisions. Initial-state and final-state interactions of the struck quark, the soft-gluon rescattering associated with its Wilson line, lead to Bjorken-scaling single-spin asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam-Tung relation in Drell-Yan reactions, as well as nuclear shadowing and antishadowing. The Gribov-Glauber theory predicts that antishadowing of nuclear structure functions is not universal, but instead depends on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence measured in deep-inelastic neutrino scattering. Since shadowing and antishadowing arise from the physics of leading-twist diffractive deep inelastic scattering, one cannot attribute such phenomena to the structure of the nucleus itself. It is thus important to distinguish 'static' structure functions, the probability distributions computed from the square of the target light-front wavefunctions, versus 'dynamical' structure functions which include the effects of the final-state rescattering of the struck quark. The importance of the J = 0 photon-quark QCD contact interaction in deeply virtual Compton scattering is also emphasized. The scheme-independent BLM method for setting the renormalization scale is discussed. Eliminating the renormalization scale ambiguity greatly improves the precision of QCD predictions and increases the sensitivity of searches for new physics at the LHC

  1. Novel QCD Phenomenology

    NASA Astrophysics Data System (ADS)

    Brodsky, Stanley J.

    2011-04-01

    I review a number of topics where conventional wisdom in hadron physics has been challenged. For example, hadrons can be produced at large transverse momentum directly within a hard QCD subprocess, rather than from jet fragmentation. Such "direct" higher-twist processes can explain the deviations from perturbative QCD predictions in measurements of inclusive hadron cross sections at fixed {xT} = 2{pT}/√ s , as well as the "baryon anomaly, the anomalously large proton-to-pion ratio seen in high centrality heavy ion collisions. Initial-state and final-state interactions of the struck quark, soft-gluon rescattering associated with its Wilson line lead to Bjorken-scaling single-spin asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam-Tung relation in Drell-Yan reactions, as well as nuclear shadowing and antishadowing. The Gribov-Glauber theory predicts that antishadowing of nuclear structure functions is not universal, but instead depends on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence measured in deep-inelastic neutrino scattering. Since shadowing and antishadowing arise from the physics of leading-twist diffractive deep inelastic scattering, one cannot attribute such phenomena to the structure of the nucleus itself. It is thus important to distinguish "static" structure functions, the probability distributions computed from the square of the target light-front wavefunctions, versus "dynamical" structure functions which include the effects of the final-state rescattering of the struck quark. The importance of the J = 0 photon-quark QCD contact interaction in deeply virtual Compton scattering is also emphasized. The scheme-independent BLM method for setting the renormalization scale is discussed. The elimination of the renormalization scale ambiguity would greatly improve the precision of QCD predictions and increase the sensitivity of searches for new physics at the LHC. Other novel

  2. Baryons in holographic QCD

    SciTech Connect

    Nawa, Kanabu; Suganuma, Hideo; Kojo, Toru

    2007-04-15

    We study baryons in holographic QCD with D4/D8/D8 multi-D-brane system. In holographic QCD, the baryon appears as a topologically nontrivial chiral soliton in a four-dimensional effective theory of mesons. We call this topological soliton brane-induced Skyrmion. Some review of D4/D8/D8 holographic QCD is presented from the viewpoints of recent hadron physics and QCD phenomenologies. A four-dimensional effective theory with pions and {rho} mesons is uniquely derived from the non-Abelian Dirac-Born-Infeld (DBI) action of D8 brane with D4 supergravity background at the leading order of large N{sub c}, without small amplitude expansion of meson fields to discuss chiral solitons. For the hedgehog configuration of pion and {rho}-meson fields, we derive the energy functional and the Euler-Lagrange equation of brane-induced Skyrmion from the meson effective action induced by holographic QCD. Performing the numerical calculation, we obtain the soliton solution and figure out the pion profile F(r) and the {rho}-meson profile G-tilde(r) of the brane-induced Skyrmion with its total energy, energy density distribution, and root-mean-square radius. These results are compared with the experimental quantities of baryons and also with the profiles of standard Skyrmion without {rho} mesons. We analyze interaction terms of pions and {rho} mesons in brane-induced Skyrmion, and find a significant {rho}-meson component appearing in the core region of a baryon.

  3. Detailed analysis of the tetraquark potential and flip-flop in SU(3) lattice QCD

    SciTech Connect

    Okiharu, Fumiko; Suganuma, Hideo; Takahashi, Toru T.

    2005-07-01

    We perform the detailed study of the tetraquark (4Q) potential V{sub 4Q} for various QQ-QQ systems in SU(3) lattice QCD with {beta}=6.0 and 16{sup 3}x32 at the quenched level. For about 200 different patterns of 4Q systems, V{sub 4Q} is extracted from the 4Q Wilson loop in 300 gauge configurations, with the smearing method to enhance the ground-state component. We calculate V{sub 4Q} for planar, twisted, asymmetric, and large-size 4Q configurations, respectively. Here, the calculation for large-size 4Q configurations is done by identifying 16{sup 2}x32 as the spatial size and 16 as the temporal one, and the long-distance confinement force is particularly analyzed in terms of the flux-tube picture. When QQ and QQ are well separated, V{sub 4Q} is found to be expressed as the sum of the one-gluon-exchange Coulomb term and multi-Y-type linear term based on the flux-tube picture. When the nearest quark and antiquark pair is spatially close, the system is described as a 'two-meson' state. We observe a flux-tube recombination called a 'flip-flop' between the connected 4Q state and the two-meson state around the level-crossing point. This leads to infrared screening of the long-range color forces between (anti)quarks belonging to different mesons, and results in the absence of the color van der Waals force between two mesons.

  4. Conceptual Aspects of Gauge/Gravity Duality

    NASA Astrophysics Data System (ADS)

    De Haro, Sebastian; Mayerson, Daniel R.; Butterfield, Jeremy N.

    2016-11-01

    We give an introductory review of gauge/gravity duality, and associated ideas of holography, emphasising the conceptual aspects. The opening sections gather the ingredients, viz. anti-de Sitter spacetime, conformal field theory and string theory, that we need for presenting, in Sect. 5, the central and original example: Maldacena's AdS/CFT correspondence. Sections 6 and 7 develop the ideas of this example, also in applications to condensed matter systems, QCD, and hydrodynamics. Sections 8 and 9 discuss the possible extensions of holographic ideas to de Sitter spacetime and to black holes. Section 10 discusses the bearing of gauge/gravity duality on two philosophical topics: the equivalence of physical theories, and the idea that spacetime, or some features of it, are emergent.

  5. Exact Solution of the One-Dimensional Non-Abelian Coulomb Gas at Large {ital N}

    SciTech Connect

    Semenoff, G.W.; Tirkkonen, O.; Zarembo, K. |

    1996-09-01

    The problem of computing the thermodynamic properties of a one-dimensional gas of particles which transform in the adjoint representation of the gauge group and interact through non-Abelian electric fields is formulated and solved in the large {ital N} limit. The explicit solution exhibits a first order confinement-deconfinement phase transition with computable properties and describes two-dimensional adjoint QCD in the limit where matter field masses are large. {copyright} {ital 1996 The American Physical Society.}

  6. Strain gauge installation tool

    DOEpatents

    Conard, Lisa Marie

    1998-01-01

    A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  7. PREFACE: Strongly Coupled Coulomb Systems Strongly Coupled Coulomb Systems

    NASA Astrophysics Data System (ADS)

    Neilson, David; Senatore, Gaetano

    2009-05-01

    This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS), held from 29 July-2 August 2008 at the University of Camerino. Camerino is an ancient hill-top town located in the Apennine mountains of Italy, 200 kilometres northeast of Rome, with a university dating back to 1336. The Camerino conference was the 11th in a series which started in 1977: 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (hosted by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (hosted by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, New York, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) 2005: Moscow, Russia (hosted by Vladimir E Fortov and Vladimir Vorob'ev). The name of the series was changed in 1996 from Strongly Coupled Plasmas to Strongly Coupled Coulomb Systems to reflect a wider range of topics. 'Strongly Coupled Coulomb Systems' encompasses diverse many-body systems and physical conditions. The purpose of the conferences is to provide a regular international forum for the presentation and discussion of research achievements and ideas relating to a variety of plasma, liquid and condensed matter systems that are dominated by strong Coulomb interactions between their constituents. Each meeting has seen an evolution of topics and emphases that have followed new discoveries and new techniques. The field has continued to see new experimental tools and access to new strongly coupled conditions, most recently in the areas of warm matter, dusty plasmas

  8. The quark propagator in QCD and G2 QCD

    NASA Astrophysics Data System (ADS)

    Contant, Romain; Huber, Markus Q.

    2017-03-01

    QCD-like theories provide testing grounds for truncations of functional equations at non-zero density, since comparisons with lattice results are possible due to the absence of the sign problem. As a first step towards such a comparison, we determine for QCD and G2 QCD the chiral and confinement/deconfinement transitions from the quark propagator Dyson-Schwinger equation at zero chemical potential by calculating the chiral and dual chiral condensates, respectively.

  9. Quark propagation in the instantons of lattice QCD

    NASA Astrophysics Data System (ADS)

    Trewartha, Daniel; Kamleh, Waseem; Leinweber, Derek; Roberts, Dale S.

    2013-08-01

    We quantitatively examine the extent to which instanton degrees of freedom, contained within standard Monte-Carlo generated gauge-field configurations, can maintain the characteristic features of the mass and renormalization functions of the nonperturbative quark propagator. We use over-improved stout-link smearing to isolate instanton effects on the lattice. Using a variety of measures, we illustrate how gauge fields consisting almost solely of instantonlike objects are produced after only 50 sweeps of smearing. We find a full vacuum, with a packing fraction more than three times larger than phenomenological models predict. We calculate the overlap quark propagator on these smeared configurations, and find that even at high levels of smearing the majority of the characteristic features of the propagator are reproduced. We thus conclude that instantons contained within standard Monte-Carlo generated gauge-field configurations are the degrees of freedom responsible for the dynamical generation of mass observed in lattice QCD.

  10. Noncommutative QED+QCD and the {beta} function for QED

    SciTech Connect

    Ettefaghi, M. M.; Haghighat, M.; Mohammadi, R.

    2010-11-15

    QED based on {theta}-unexpanded noncomutative space-time in contrast with the noncommutative QED based on {theta}-expanded U(1) gauge theory via the Seiberg-Witten map is one-loop renormalizable. Meanwhile it suffers from asymptotic freedom that is not in agreement with the experiment. We show that the QED part of the U{sub *}(3)xU{sub *}(1) gauge group as an appropriate gauge group for the noncommutative QED+QCD is not only one-loop renormalizable but also has a {beta} function that can be positive, negative and even zero. In fact the {beta} function depends on the mixing parameter {delta}{sub 13} as a free parameter and it will be equal to its counterpart in the ordinary QED for {delta}{sub 13}=0.367{pi}.

  11. A holographic study of the gauged NJL model

    NASA Astrophysics Data System (ADS)

    Clemens, Will; Evans, Nick

    2017-08-01

    The Nambu Jona-Lasinio model of chiral symmetry breaking predicts a second order chiral phase transition. If the fermions in addition have non-abelian gauge interactions then the transition is expected to become a crossover as the NJL term enhances the IR chiral symmetry breaking of the gauge theory. We study this behaviour in the holographic Dynamic AdS/QCD description of a non-abelian gauge theory with the NJL interaction included using Witten's multi-trace prescription. We study the behaviour of the mesonic spectrum as a function of the NJL coupling and the ratio of the UV cut off scale to the dynamical scale of the gauge theory.

  12. Full QCD hadron spectroscopy with two flavors of dynamical Kogut-Susskind quarks on the lattice

    SciTech Connect

    Fukugita, M. ); Ishizuka, N. , Ibaraki 305 ); Mino, H. ); Okawa, M. , Ibaraki 305 ); Ukawa, A. )

    1993-05-15

    A full lattice QCD simulation is carried out with two flavors of Kogut-Susskind staggered dynamical quarks using lattices of a size ranging from 4[sup 4] to 20[sup 4] at the gauge coupling constant [beta]=6/[ital g][sup 2]=5.7 with the quark mass of [ital m][sub [ital q

  13. Euler-Lagrange Equations for the Gribov Reggeon Calculus in QCD and in Gravity

    NASA Astrophysics Data System (ADS)

    Lipatov, L. N.

    The theory of the high energy scattering in QCD and gravity is based on the reggeization of gluons and gravitons, respectively. We discuss the corresponding effective actions for reggeized particle interactions. The Euler-Lagrange equations in these theories are constructed with a variational approach for the effective actions and by using their invariance under the gauge and general coordinate transformations.

  14. Euler-Lagrange equations for the Gribov reggeon calculus in QCD and in gravity

    NASA Astrophysics Data System (ADS)

    Lipatov, L. N.

    2016-10-01

    The theory of the high energy scattering in QCD and gravity is based on the reggeization of gluons and gravitons, respectively. We discuss the corresponding effective actions for reggeized particle interactions. The Euler-Lagrange equations in these theories are constructed with a variational approach for the effective actions and by using their invariance under the gauge and general coordinate transformations.

  15. Gauge engineering and propagators

    NASA Astrophysics Data System (ADS)

    Maas, Axel

    2017-03-01

    Beyond perturbation theory gauge-fixing becomes more involved due to the Gribov-Singer ambiguity: The appearance of additional gauge copies requires to define a procedure how to handle them. For the case of Landau gauge the structure and properties of these additional gauge copies will be investigated. Based on these properties gauge conditions are constructed to account for these gauge copies. The dependence of the propagators on the choice of these complete gauge-fixings will then be investigated using lattice gauge theory for Yang-Mills theory. It is found that the implications for the infrared, and to some extent mid-momentum behavior, can be substantial. In going beyond the Yang-Mills case it turns out that the influence of matter can generally not be neglected. This will be briefly discussed for various types of matter.

  16. Higgsed Gauge-flation

    NASA Astrophysics Data System (ADS)

    Adshead, Peter; Sfakianakis, Evangelos I.

    2017-08-01

    We study a variant of Gauge-flation where the gauge symmetry is spontaneously broken by a Higgs sector. We work in the Stueckelberg limit and demonstrate that the dynamics remain (catastrophically) unstable for cases where the gauge field masses satisfy γ < 2, where γ = g 2 ψ 2/ H 2, g is the gauge coupling, ψ is the gauge field vacuum expectation value, and H is the Hubble rate. We compute the spectrum of density fluctuations and gravitational waves, and show that the model can produce observationally viable spectra. The background gauge field texture violates parity, resulting in a chiral gravitational wave spectrum. This arises due to an exponential enhancement of one polarization of the spin-2 fluctuation of the gauge field. Higgsed Gauge-flation can produce observable gravitational waves at inflationary energy scales well below the GUT scale.

  17. Phenomenology of strongly coupled chiral gauge theories

    DOE PAGES

    Bai, Yang; Berger, Joshua; Osborne, James; ...

    2016-11-25

    A sector with QCD-like strong dynamics is common in models of non-standard physics. Such a model could be accessible in LHC searches if both confinement and big-quarks charged under the confining group are at the TeV scale. Big-quark masses at this scale can be explained if the new fermions are chiral under a new U(1)' gauge symmetry such that their bare masses are related to the U(1)'-breaking and new confinement scales. Here we present a study of a minimal GUT-motivated and gauge anomaly-free model with implications for the LHC Run 2 searches. We find that the first signatures of suchmore » models could appear as two gauge boson resonances. The chiral nature of the model could be confirmed by observation of a Z'γ resonance, where the Z' naturally has a large leptonic branching ratio because of its kinetic mixing with the hypercharge gauge boson.« less

  18. Cosmological properties of a gauged axion

    SciTech Connect

    Coriano, Claudio; Mariano, Antonio; Guzzi, Marco; Lazarides, George

    2010-09-15

    We analyze the most salient cosmological features of axions in extensions of the standard model with a gauged anomalous extra U(1) symmetry. The model is built by imposing the constraint of gauge invariance in the anomalous effective action, which is extended with Wess-Zumino counterterms. These generate axionlike interactions of the axions to the gauge fields and a gauged shift symmetry. The scalar sector is assumed to acquire a nonperturbative potential after inflation, at the electroweak phase transition, which induces a mixing of the Stueckelberg field of the model with the scalars of the electroweak sector, and at the QCD phase transition. We discuss the possible mechanisms of sequential misalignments which could affect the axions of these models, and generated, in this case, at both transitions. We compute the contribution of these particles to dark matter, quantifying their relic densities as a function of the Stueckelberg mass. We also show that models with a single anomalous U(1) in general do not account for the dark energy, due to the presence of mixed U(1)-SU(3) anomalies.

  19. Lattice Landau Gauge via Stereographic Projection

    NASA Astrophysics Data System (ADS)

    von Smekal, L.; Mehta, D.; Sternbeck, A.

    alexander.jorkowski@student.adelaide.edu.au, dhagash.mehta@adelaide.edu.au, andre.sternbeck@adelaide.edu.au The complete cancellation of Gribov copies and the Neuberger 0/0 problem of lattice BRST can be avoided in modified lattice Landau gauge. In compact U(1), where the problem is a lattice artifact, there remain to be Gribov copies but their number is exponentially reduced. Moreover, there is no cancellation of copies there as the sign of the Faddeev-Popov determinant is posi- tive. Applied to the maximal Abelian subgroup this avoids the perfect cancellation amongst the remaining Gribov copies for SU(N) also. In addition, based on a definition of gauge fields on the lattice as stereographically-projected link variables, it provides a framework for gauge fixed Monte-Carlo simulations. This will include all Gribov copies in the spirit of BRST. Their average is not zero, as demonstrated explicitly in simple models. This might resolve present discrepancies between gauge-fixed lattice and continuum studies of QCD Green’s functions.

  20. National Computational Infrastructure for Lattice Gauge Theory

    SciTech Connect

    Reed, Daniel, A

    2008-05-30

    In this document we describe work done under the SciDAC-1 Project National Computerational Infrastructure for Lattice Gauge Theory. The objective of this project was to construct the computational infrastructure needed to study quantim chromodynamics (QCD). Nearly all high energy and nuclear physicists in the United States working on the numerical study of QCD are involved in the project, as are Brookhaven National Laboratory (BNL), Fermi National Accelerator Laboratory (FNAL), and Thomas Jefferson National Accelerator Facility (JLab). A list of the serior participants is given in Appendix A.2. The project includes the development of community software for the effective use of the terascale computers, and the research and development of commodity clusters optimized for the study of QCD. The software developed as part of this effort is pubicly available, and is being widely used by physicists in the United States and abroad. The prototype clusters built with SciDAC-1 fund have been used to test the software, and are available to lattice guage theorists in the United States on a peer reviewed basis.

  1. Subcritical string and large N QCD

    SciTech Connect

    Thorn, Charles B.

    2008-10-15

    We pursue the possibility of using subcritical string theory in 4 spacetime dimensions to establish a string dual for large N QCD. In particular we study the even G-parity sector of the 4 dimensional Neveu-Schwarz dual resonance model as the natural candidate for this string theory. Our point of view is that the open string dynamics given by this model will determine the appropriate subcritical closed string theory, a tree level background of which should describe the sum of planar multiloop open string diagrams. We examine the one-loop open string diagram, which contains information about the closed string spectrum at weak coupling. Higher loop open string diagrams will be needed to determine closed string interactions. We also analyze the field theory limit of the one-loop open string diagram and recover the correct running coupling behavior of the limiting gauge theory.

  2. Baryon number current in holographic noncommutative QCD

    NASA Astrophysics Data System (ADS)

    Nakajima, Tadahito; Ohtake, Yukiko; Suzuki, Kenji

    2017-08-01

    We consider the noncommutative deformation of the finite-temperature holographic QCD (Sakai-Sugimoto) model in external electric and magnetic field and evaluate the effect of the noncommutativity on the properties of the conductor-insulator phase transition associated with a baryon number current. Although the noncommutative deformation of the gauge theory does not change the phase structure with respect to the baryon number current, the transition temperature Tc, the transition electric field ec, and magnetic field bc in the conductor-insulator phase transition depend on the noncommutativity parameter θ . Namely, the noncommutativity of space coordinates have an influence on the shape of the phase diagram for the conductor-insulator phase transition. On the other hand, the allowed range of the noncommutativity parameter can be restricted by the reality condition of the constants of motion.

  3. Cut-constructible part of QCD amplitudes

    SciTech Connect

    Britto, Ruth; Feng Bo; Mastrolia, Pierpaolo

    2006-05-15

    Unitarity cuts are widely used in analytic computation of loop amplitudes in gauge theories such as QCD. We expand upon the technique introduced in hep-ph/0503132 to carry out any finite unitarity cut integral. This technique naturally separates the contributions of bubble, triangle and box integrals in one-loop amplitudes and is not constrained to any particular helicity configurations. Loop momentum integration is reduced to a sequence of algebraic operations. We discuss the extraction of the residues at higher-order poles. Additionally, we offer concise algebraic formulas for expressing coefficients of three-mass triangle integrals. As an application, we compute all remaining coefficients of bubble and triangle integrals for nonsupersymmetric six-gluon amplitudes.

  4. Hadron Resonances from QCD

    SciTech Connect

    Dudek, Jozef

    2016-03-01

    I describe how hadron-hadron scattering amplitudes are related to the eigenstates of QCD in a finite cubic volume. The discrete spectrum of such eigenstates can be determined from correlation functions computed using lattice QCD, and the corresponding scattering amplitudes extracted. I review results from the Hadron Spectrum Collaboration who have used these finite volume methods to study ππ elastic scattering, including the ρ resonance, as well as coupled-channel πK, ηK scattering. The very recent extension to the case where an external current acts is also presented, considering the reaction πγ* → ππ, from which the unstable ρ → πγ transition form factor is extracted. Ongoing calculations are advertised and the outlook for finite volume approaches is presented.

  5. Hybrid baryons in QCD

    SciTech Connect

    Dudek, Jozef J.; Edwards, Robert G.

    2012-03-21

    In this study, we present the first comprehensive study of hybrid baryons using lattice QCD methods. Using a large basis of composite QCD interpolating fields we extract an extensive spectrum of baryon states and isolate those of hybrid character using their relatively large overlap onto operators which sample gluonic excitations. We consider the spectrum of Nucleon and Delta states at several quark masses finding a set of positive parity hybrid baryons with quantum numbers $N_{1/2^+},\\,N_{1/2^+},\\,N_{3/2^+},\\, N_{3/2^+},\\,N_{5/2^+},\\,$ and $\\Delta_{1/2^+},\\, \\Delta_{3/2^+}$ at an energy scale above the first band of `conventional' excited positive parity baryons. This pattern of states is compatible with a color octet gluonic excitation having $J^{P}=1^{+}$ as previously reported in the hybrid meson sector and with a comparable energy scale for the excitation, suggesting a common bound-state construction for hybrid mesons and baryons.

  6. QCD tests at CDF

    SciTech Connect

    Kovacs, E.; CDF Collaboration

    1996-02-01

    We present results for the inclusive jet cross section and the dijet mass distribution. The inclusive cross section and dijet mass both exhibit significant deviations from the predictions of NLO QCD for jets with E{sub T}>200 GeV, or dijet masses > 400 GeV/c{sup 2}. We show that it is possible, within a global QCD analysis that includes the CDF inclusive jet data, to modify the gluon distribution at high x. The resulting increase in the jet cross-section predictions is 25-35%. Owing to the presence of k{sub T} smearing effects, the direct photon data does not provide as strong a constraint on the gluon distribution as previously thought. A comparison of the CDF and UA2 jet data, which have a common range in x, is plagued by theoretical and experimental uncertainties, and cannot at present confirm the CDF excess or the modified gluon distribution.

  7. Introduction to lattice QCD

    SciTech Connect

    Gupta, R.

    1998-12-31

    The goal of the lectures on lattice QCD (LQCD) is to provide an overview of both the technical issues and the progress made so far in obtaining phenomenologically useful numbers. The lectures consist of three parts. The author`s charter is to provide an introduction to LQCD and outline the scope of LQCD calculations. In the second set of lectures, Guido Martinelli will discuss the progress they have made so far in obtaining results, and their impact on Standard Model phenomenology. Finally, Martin Luescher will discuss the topical subjects of chiral symmetry, improved formulation of lattice QCD, and the impact these improvements will have on the quality of results expected from the next generation of simulations.

  8. Gauge Messenger Models

    SciTech Connect

    Kim, Hyung Do

    2006-11-28

    We consider gauge messenger models in which X and Y gauge bosons and gauginos are messengers of supersymmetry breaking. In simple gauge messenger models, all the soft parameters except {mu} and B{mu} are calculated in terms of a single scale parameter MSUSY which is proportional to F / MGUT. Unique prediction on dark matter in gauge messenger models is discussed. (Based on hep-ph/0601036 and hep-ph/0607169)

  9. Direct gauge mediation of uplifted metastable supersymmetry breaking in supergravity

    SciTech Connect

    Maru, Nobuhito

    2010-10-01

    We propose a direct gauge mediation model based on an uplifted metastable supersymmetry (SUSY) breaking coupled to supergravity. A constant superpotential plays an essential role to fix the moduli as well as breaking SUSY and R symmetry and the cancellation of the cosmological constant. Gaugino masses are generated at leading order of SUSY breaking scale, and comparable to the sfermion masses as in the ordinary gauge mediation. The Landau pole problem for QCD coupling can be easily solved since more than half of messengers become superheavy, which are heavier than the grand unified theory (GUT) scale.

  10. Charmonium from Lattice QCD

    SciTech Connect

    Jozef Dudek

    2007-08-05

    Charmonium is an attractive system for the application of lattice QCD methods. While the sub-threshold spectrum has been considered in some detail in previous works, it is only very recently that excited and higher-spin states and further properties such as radiative transitions and two-photon decays have come to be calculated. I report on this recent progress with reference to work done at Jefferson Lab.

  11. Future directions for QCD

    SciTech Connect

    Bjorken, J.D.

    1996-10-01

    New directions for exploring QCD at future high-energy colliders are sketched. These include jets within jets. BFKL dynamics, soft and hard diffraction, searches for disoriented chiral condensate, and doing a better job on minimum bias physics. The new experimental opportunities include electron-ion collisions at HERA, a new collider detector at the C0 region of the TeVatron, and the FELIX initiative at the LHC.

  12. Minijets, QCD, and unitarity

    SciTech Connect

    Capella, A.; Tran Thanh Van, J.; Kwiecinski, J.

    1987-05-18

    We introduce the minijet cross section, computed from QCD, together with a standard soft component, into a unitarizaton scheme (eikonal model) and show that most of the increase of the inelastic cross section between CERN ISR and SPS collider energies is due to the soft component. We also show that the main properties of minijet production, observed by the UA1 collaboration, can be understood by the introduction of semihard scattering in the dual parton model.

  13. QCD tests with CDF

    SciTech Connect

    Flaugher, B.

    1992-09-01

    Measurement of scaling violations, the inclusive photon and diphoton cross sections as well as the photon-jet and jet-jet angular distributions are discussed and compared to leading order and next-to-leading order QCD. A study of four-jet events is described, with a limit on the cross section for double parton scattering. The multiplicity of jets in W boson events is compared to theoretical predictions.

  14. QCD results from the Tevatron

    SciTech Connect

    C. Mesropian

    2002-07-12

    The Tevatron hadron collider provides the unique opportunity to study Quantum Chromodynamics, QCD, at the highest energies. The results summarized in this talk, although representing different experimental objects, as hadronic jets and electromagnetic clusters, serve to determine the fundamental input ingredients of QCD as well as to search for new physics. The authors present results from QCD studies at the Tevatron from Run 1 data, including jet and direct photon production, and a measurement of the strong coupling constant.

  15. Hadronic Resonances from Lattice QCD

    SciTech Connect

    John Bulava; Robert Edwards; George Fleming; K. Jimmy Juge; Adam C. Lichtl; Nilmani Mathur; Colin Morningstar; David Richards; Stephen J. Wallace

    2007-06-16

    The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

  16. Hadronic Resonances from Lattice QCD

    SciTech Connect

    Lichtl, Adam C.; Bulava, John; Morningstar, Colin; Edwards, Robert; Mathur, Nilmani; Richards, David; Fleming, George; Juge, K. Jimmy; Wallace, Stephen J.

    2007-10-26

    The determination of the pattern of hadronic resonances as predicted by Quantum Chromodynamics requires the use of non-perturbative techniques. Lattice QCD has emerged as the dominant tool for such calculations, and has produced many QCD predictions which can be directly compared to experiment. The concepts underlying lattice QCD are outlined, methods for calculating excited states are discussed, and results from an exploratory Nucleon and Delta baryon spectrum study are presented.

  17. Chaos in Chiral Condensates in Gauge Theories

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Murata, Keiju; Yoshida, Kentaroh

    2016-12-01

    Assigning a chaos index for dynamics of generic quantum field theories is a challenging problem because the notion of a Lyapunov exponent, which is useful for singling out chaotic behavior, works only in classical systems. We address the issue by using the AdS /CFT correspondence, as the large Nc limit provides a classicalization (other than the standard ℏ→0 ) while keeping nontrivial quantum condensation. We demonstrate the chaos in the dynamics of quantum gauge theories: The time evolution of homogeneous quark condensates ⟨q ¯q ⟩ and ⟨q ¯γ5q ⟩ in an N =2 supersymmetric QCD with the S U (Nc) gauge group at large Nc and at a large 't Hooft coupling λ ≡NcgYM2 exhibits a positive Lyapunov exponent. The chaos dominates the phase space for energy density E ≳(6 ×1 02)×mq4(Nc/λ2), where mq is the quark mass. We evaluate the largest Lyapunov exponent as a function of (Nc,λ ,E ) and find that the N =2 supersymmetric QCD is more chaotic for smaller Nc.

  18. Confinement and deconfinement in gauge theories

    NASA Astrophysics Data System (ADS)

    Holland, Kieran

    In this thesis, we examine properties of the confined and deconfined phases of non-Abelian gauge theories. In one part of the thesis, we examine a String Theory prediction made for Supersymmetric Yang-Mills theory. The prediction is that a QCD string emanating from a quark and carrying color flux can end on a domain wall which has no color charge. Using effective field theoretic methods, we explain how the domain wall carries the color flux of the QCD string to spatial infinity. We use this explanation to predict the phase structure of Supersymmetric Yang- Mills theory. We also examine universal critical phenomena associated with these domain walls. In the rest of the thesis, we show analytically how static test quarks call be confined, even in the deconfined bulk phase. We observe this unusual confinement numerically in an effective field theory for the gauge theory using highly efficient cluster techniques. This is also a new method to determine the energy cost of domain walls separating bulk phases. (Copies available exclusively from MIT Libraries, Rm. 14-0551, Cambridge, MA 02139- 4307. Ph. 617-253-5668; Fax 617-253-1690.)

  19. Non-perturbative study of QCD correlators

    NASA Astrophysics Data System (ADS)

    Lokhov, A. Y.

    2006-07-01

    This PhD dissertation is devoted to a non-perturbative study of QCD correlators. The main tool that we use is lattice QCD. We concentrated our efforts on the study of the main correlators of the pure Yang - Mills theory in the Landau gauge, namely the ghost and the gluon propagators. We are particularly interested in determining the Lqcd parameter. It is extracted by means of perturbative predictions available up to NNNLO. The related topic is the influence of non-perturbative effects that show up as appearance of power-corrections to the low-momentum behaviour of the Green functions. A new method of removing these power corrections allows a better estimate of Lqcd. Our result is Lambda^{n_f=0}_{ms} = 269(5)^{+12}_{-9} MeV. Another question that we address is the infrared behaviour of Green functions, at momenta of order and below Lqcd. At low energy the momentum dependence of the propagators changes considerably, and this is probably related to confinement. The lattice approach allows to check the predictions of analytical methods because it gives access to non-perturbative correlators. According to our analysis the gluon propagator is finite and non-zero at vanishing momentum, and the power-law behaviour of the ghost propagator is the same as in the free case.

  20. Lattice-motivated holomorphic nearly perturbative QCD

    NASA Astrophysics Data System (ADS)

    Ayala, César; Cvetič, Gorazd; Kögerler, Reinhart

    2017-07-01

    Newer lattice results indicate that, in the Landau gauge at low spacelike momenta, the gluon propagator and the ghost dressing function are finite nonzero. This leads to a definition of the QCD running coupling, in a specific scheme, that goes to zero at low spacelike momenta. We construct a running coupling which fulfills these conditions, and at the same time reproduces to a high precision the perturbative behavior at high momenta. The coupling is constructed in such a way that it reflects qualitatively correctly the holomorphic (analytic) behavior of spacelike observables in the complex plane of the squared momenta, as dictated by the general principles of quantum field theories. Further, we require the coupling to reproduce correctly the nonstrange semihadronic decay rate of tau lepton which is the best measured low-momentum QCD observable with small higher-twist effects. Subsequent application of the Borel sum rules to the V + A spectral functions of tau lepton decays, as measured by OPAL Collaboration, determines the values of the gluon condensate and of the V + A six-dimensional condensate, and reproduces the data to a significantly higher precision than the usual \\overline{{MS}} running coupling.

  1. Hadron potentials within the gauge/string correspondence

    SciTech Connect

    Jugeau, Frederic

    2010-08-15

    It is known, since the 70s, that the large N 't Hooft limit of gauge theories is related to string theories. In 1998, J. M. Maldacena identified precisely such a relation: the so-called AdS/CFT correspondence which speculates a duality between a large N strongly-coupled supersymmetric and conformal Yang-Mills theory in four dimensions and a weakly-coupled string theory defined in a five-dimensional anti-de Sitter AdS{sub 5} space-time. This review aims at introducing concepts and methods used to derive, in the framework of the gauge/string correspondence, the interaction potentials of mesons and baryons at zero and finite temperature. The dual string configurations associated with the different kinds of hadrons are described and their behaviours at short and large distances are understood. Although the application of Maldacena's AdS/CFT conjecture to QCD is not straightforward, QCD being neither supersymmetric nor conformal, the AdS/QCD correspondence approach attempts to identify the dual theory of QCD. Especially, the study of heavy quark-antiquark bound-states leads to establish general dual criteria for the confinement.

  2. Dynamics for QCD on an Infinite Lattice

    NASA Astrophysics Data System (ADS)

    Grundling, Hendrik; Rudolph, Gerd

    2017-02-01

    We prove the existence of the dynamics automorphism group for Hamiltonian QCD on an infinite lattice in R^3, and this is done in a C*-algebraic context. The existence of ground states is also obtained. Starting with the finite lattice model for Hamiltonian QCD developed by Kijowski, Rudolph (cf. J Math Phys 43:1796-1808 [15], J Math Phys 46:032303 [16]), we state its field algebra and a natural representation. We then generalize this representation to the infinite lattice, and construct a Hilbert space which has represented on it all the local algebras (i.e., kinematics algebras associated with finite connected sublattices) equipped with the correct graded commutation relations. On a suitably large C*-algebra acting on this Hilbert space, and containing all the local algebras, we prove that there is a one parameter automorphism group, which is the pointwise norm limit of the local time evolutions along a sequence of finite sublattices, increasing to the full lattice. This is our global time evolution. We then take as our field algebra the C*-algebra generated by all the orbits of the local algebras w.r.t. the global time evolution. Thus the time evolution creates the field algebra. The time evolution is strongly continuous on this choice of field algebra, though not on the original larger C*-algebra. We define the gauge transformations, explain how to enforce the Gauss law constraint, show that the dynamics automorphism group descends to the algebra of physical observables and prove that gauge invariant ground states exist.

  3. Renormalization of Extended QCD2

    NASA Astrophysics Data System (ADS)

    Fukaya, Hidenori; Yamamura, Ryo

    2015-10-01

    Extended QCD (XQCD), proposed by Kaplan [D. B. Kaplan, arXiv:1306.5818], is an interesting reformulation of QCD with additional bosonic auxiliary fields. While its partition function is kept exactly the same as that of original QCD, XQCD naturally contains properties of low-energy hadronic models. We analyze the renormalization group flow of 2D (X)QCD, which is solvable in the limit of a large number of colors N_c, to understand what kind of roles the auxiliary degrees of freedom play and how the hadronic picture emerges in the low-energy region.

  4. Recent QCD results from CDF

    SciTech Connect

    I. Gorelov

    2001-12-28

    Experimental results on QCD measurements obtained in recent analyses and based on data collected with CDF Detector from the Run 1b Tevatron running cycle are presented. The scope of the talk includes major QCD topics: a measurement of the strong coupling constant {alpha}{sub s}, extracted from inclusive jet spectra and the underlying event energy contribution to a jet cone. Another experimental object of QCD interest, prompt photon production, is also discussed and the updated measurements by CDF of the inclusive photon cross section at 630 GeV and 1800 GeV, and the comparison with NLO QCD predictions is presented.

  5. An Anderson-like model of the QCD chiral transition

    NASA Astrophysics Data System (ADS)

    Giordano, Matteo; Kovács, Tamás G.; Pittler, Ferenc

    2016-06-01

    We study the problems of chiral symmetry breaking and eigenmode localisation in finite-temperature QCD by looking at the lattice Dirac operator as a random Hamiltonian. We recast the staggered Dirac operator into an unconventional three-dimensional Anderson Hamiltonian ("Dirac-Anderson Hamiltonian") carrying internal degrees of freedom, with disorder provided by the fluctuations of the gauge links. In this framework, we identify the features relevant to chiral symmetry restoration and localisation of the low-lying Dirac eigenmodes in the ordering of the local Polyakov lines, and in the related correlation between spatial links across time slices, thus tying the two phenomena to the deconfinement transition. We then build a toy model based on QCD and on the Dirac-Anderson approach, replacing the Polyakov lines with spin variables and simplifying the dynamics of the spatial gauge links, but preserving the above-mentioned relevant dynamical features. Our toy model successfully reproduces the main features of the QCD spectrum and of the Dirac eigenmodes concerning chiral symmetry breaking and localisation, both in the ordered (deconfined) and disordered (confined) phases. Moreover, it allows us to study separately the roles played in the two phenomena by the diagonal and the off-diagonal terms of the Dirac-Anderson Hamiltonian. Our results support our expectation that chiral symmetry restoration and localisation of the low modes are closely related, and that both are triggered by the deconfinement transition.

  6. Color Confinement and Screening in the θ Vacuum of QCD.

    PubMed

    Kharzeev, Dmitri E; Levin, Eugene M

    2015-06-19

    QCD perturbation theory ignores the compact nature of the SU(3) gauge group that gives rise to the periodic θ vacuum of the theory. We propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the θ vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a "glost." We evaluate the glost propagator and find that it has the form G(p)=(p(2)+χ(top)/p(2))(-1) where χ(top) is the Yang-Mills topological susceptibility related to the η' mass by the Witten-Veneziano relation; this propagator describes the confinement of gluons at distances ∼χ(top)(-1/4)≃1  fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at p(2)≫√[χ(top)], but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. Our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.

  7. The local structure of topological charge fluctuations in QCD

    SciTech Connect

    I. Horvath; S.J. Dong; T. Draper; Frank Lee; K.F. Liu; J.B. Zhang; H.B. Thacker

    2002-06-01

    We introduce the Dirac eigenmode filtering of topological charge density associated with Ginsparg-Wilson fermions as a tool to investigate the local structure of topological charge fluctuations in QCD. The resulting framework is used to demonstrate that the bulk of topological charge in QCD does not appear in the form of unit quantized lumps. This means that the mixing of ''would-be'' zeromodes associated with such lumps is probably not the prevalent microscopic mechanism for spontaneous chiral symmetry breaking in QCD. To characterize the coherent local behavior in topological charge density at low energy, we compute the charges contained in maximal coherent spheres enclosing non-overlapping peaks. We find a continuous distribution essentially ending at {approx}0.5. Finally, we study, for the first time, the overlap-operator topological-charge-density correlators and find consistency with non-positivity at nonzero physical distance. This represents a non-trivial check on the locality (in gauge paths) of the overlap Dirac operator for realistic gauge backgrounds.

  8. Dual Superconductivity in Abelian Higgs Model of QCD

    NASA Astrophysics Data System (ADS)

    Rajput, B. S.

    2017-04-01

    The study of generalized field associated with Abelian dyons has been undertaken and it has been demonstrated that topologically, a non-Abelian gauge theory is equivalent to a set of Abelian gauge theories supplemented by dyons which undergo condensation leading to confinement and consequently to superconducting model of QCD vacuum, where the Higgs field plays the role of a regulator only. Constructing the effective action for dyonic field in Abelian projection of QCD, it has been demonstrated that any charge (electrical or magnetic) of dyon screens its own direct potential to which it minimally couples and anti-screens the dual potential leading to dual superconductivity in accordance with generalized Meissner effect. In this Abelian projection of QCD an Abelian Higgs model (AHM) has been successfully constructed and it has been shown to incorporate dual superconductivity and confinement as the consequence of dyonic condensation. It has been demonstrated that in AHM t' Hooft loop creates the string (AHM-string) around which the monopole current under London limit leads to vanishing coherence length in the chromo-magnetic superconductor. It has also been shown that in London limit the squared density of monopole current around AHM-string has a maximum at the distance of the order of penetration length.

  9. Gauged linear sigma model and pion-pion scattering

    SciTech Connect

    Fariborz, Amir H.; Schechter, Joseph; Shahid, M. Naeem

    2009-12-01

    A simple gauged linear sigma model with several parameters to take the symmetry breaking and the mass differences between the vector meson and the axial vector meson into account is considered here as a possibly useful 'template' for the role of a light scalar in QCD as well as for (at a different scale) an effective Higgs sector for some recently proposed walking technicolor models. An analytic procedure is first developed for relating the Lagrangian parameters to four well established (in the QCD application) experimental inputs. One simple equation distinguishes three different cases: i. QCD with axial vector particle heavier than vector particle, ii. possible technicolor model with vector particle heavier than the axial vector one, iii. the unphysical QCD case where both the Kawarabayashi-Suzuki-Riazuddin-Fayazuddin and Weinberg relations hold. The model is applied to the s-wave pion-pion scattering in QCD. Both the near threshold region and (with an assumed unitarization) the 'global' region up to about 800 MeV are considered. It is noted that there is a little tension between the choice of 'bare' sigma mass parameter for describing these two regions. If a reasonable 'global' fit is made, there is some loss of precision in the near threshold region.

  10. PREFACE: Strongly Coupled Coulomb Systems

    NASA Astrophysics Data System (ADS)

    Fortov, Vladimir E.; Golden, Kenneth I.; Norman, Genri E.

    2006-04-01

    This special issue contains papers presented at the International Conference on Strongly Coupled Coulomb Systems (SCCS) which was held during the week of 20 24 June 2005 in Moscow, Russia. The Moscow conference was the tenth in a series of conferences. The previous conferences were organized as follows. 1977: Orleans-la-Source, France, as a NATO Advanced Study Institute on Strongly Coupled Plasmas (organized by Marc Feix and Gabor J Kalman) 1982: Les Houches, France (organized by Marc Baus and Jean-Pierre Hansen) 1986: Santa Cruz, California, USA (hosted by Forrest J Rogers and Hugh E DeWitt) 1989: Tokyo, Japan (hosted by Setsuo Ichimaru) 1992: Rochester, NY, USA (hosted by Hugh M Van Horn and Setsuo Ichimaru) 1995: Binz, Germany (hosted by Wolf Dietrich Kraeft and Manfred Schlanges) 1997: Boston, Massachusetts, USA (hosted by Gabor J Kalman) 1999: St Malo, France (hosted by Claude Deutsch and Bernard Jancovici) 2002: Santa Fe, New Mexico, USA (hosted by John F Benage and Michael S Murillo) After 1995 the name of the series was changed from `Strongly Coupled Plasmas' to the present name in order to extend the topics of the conferences. The planned frequency for the future is once every three years. The purpose of these conferences is to provide an international forum for the presentation and discussion of research accomplishments and ideas relating to a variety of plasma liquid and condensed matter systems, dominated by strong Coulomb interactions between their constituents. Strongly coupled Coulomb systems encompass diverse many-body systems and physical conditions. Each meeting has seen an evolution of topics and emphasis as new discoveries and new methods appear. This year, sessions were organized for invited presentations and posters on dense plasmas and warm matter, astrophysics and dense hydrogen, non-neutral and ultracold plasmas, dusty plasmas, condensed matter 2D and layered charged-particle systems, Coulomb liquids, and statistical theory of SCCS. Within

  11. Coulombic contribution and fat center vortex model

    SciTech Connect

    Rafibakhsh, Shahnoosh; Deldar, Sedigheh

    2007-02-27

    The fat (thick) center vortex model is one of the phenomenological models which is fairly successful to interpret the linear potential between static sources. However, the Coulombic part of the potential has not been investigated by the model yet. In an attempt to get the Coulombic contribution and to remove the concavity of the potentials, we are studying different vortex profiles and vortex sizes.

  12. Supersymmetric gauge theories on the five-sphere

    NASA Astrophysics Data System (ADS)

    Hosomichi, Kazuo; Seong, Rak-Kyeong; Terashima, Seiji

    2012-12-01

    We construct Euclidean 5d supersymmetric gauge theories on the five-sphere with vector and hypermultiplets. The SUSY transformation and the action are explicitly determined from the standard Noether procedure as well as from off-shell supergravity. Using localization techniques, the path-integral is shown to be restricted to the integration over a generalization of instantons on CP2 and the Coulomb moduli.

  13. QCD: Questions, challenges, and dilemmas

    SciTech Connect

    Bjorken, J.

    1996-11-01

    An introduction to some outstanding issues in QCD is presented, with emphasis on work by Diakonov and co-workers on the influence of the instanton vacuum on low-energy QCD observables. This includes the calculation of input valence-parton distributions for deep-inelastic scattering. 35 refs., 3 figs.

  14. QCD coupling constants and VDM

    SciTech Connect

    Erkol, G.; Ozpineci, A.; Zamiralov, V. S.

    2012-10-23

    QCD sum rules for coupling constants of vector mesons with baryons are constructed. The corresponding QCD sum rules for electric charges and magnetic moments are also derived and with the use of vector-meson-dominance model related to the coupling constants. The VDM role as the criterium of reciprocal validity of the sum rules is considered.

  15. Recent Developments in Perturbative QCD

    SciTech Connect

    Dixon, Lance J.; /SLAC

    2005-07-11

    I review recent progress in perturbative QCD on two fronts: extending next-to-next-to-leading order QCD corrections to a broader range of collider processes, and applying twistor-space methods (and related spinoffs) to computations of multi-parton scattering amplitudes.

  16. Non-perturbative effects in quantum field theory: QCD, supersymmetric QCD and axions

    NASA Astrophysics Data System (ADS)

    Wu, Weitao

    In the study of non-perturbative effects in four dimenstional non-Abelian gauge theories, instantons have played an important conceptual role. However, their role in the quantitative understanding these theories has remained obscure. In the first part of this thesis, we revisit the question of whether or not one can perform reliable semiclassical QCD computation at zero temperature. We study correlation functions with no perturbative contributions, and organize the problem by means of the operator product expansion, establishing a precise criterion for the validity of semiclassical calculation. For N f > Nc, a systematic computation is possible; for Nf < Nc, it is not. Nf = Nc is a borderline case. As an application, we describe a test of QCD lattice gauge theory computations in the chiral limit. Supersymmetry has provided a tool with which to obtain a range of exact results in field theory and string theory. Arguably the first inkling that one could obtain such results was the work of Novikov, Shifman, Vainshtein, and Zakharov (NSVZ). They argued for two exact results in gauge theories using instanton computation. First, that one could compute certain correlation functions exactly at weak coupling, and extend the results to strong coupling; second, that one could obtain exact expressions for beta-functions. However, each of these results raised questions. As methods exploiting systematic weak coupling expansions and holomorphy were developed, it became clear that the strong coupling instanton computation was incorrect. This in turn called the exact beta-function into question. In the second part of this thesis, we will provide resolutions to both of these questions. First, we explain why the instanton computation in the pure supersymmetric gauge theory is not reliable, even at short distances. The semiclassical expansion about the instanton is purely formal; if infrared divergences appear, they spoil arguments based on holomorphy. For the question of the NSVZbeta

  17. Reply to Isgur's comments on valence QCD

    SciTech Connect

    Liu, K.F.

    2000-01-12

    With the goal of understanding the complexity of QCD and the role of symmetry in dynamics, the authors studied a field theory called Valence QCD (VQCD) in which the Z graphs are forbidden so that the Fock space is limited to the valence quarks. The authors calculated nucleon form factors, matrix elements, and hadron masses both with this theory and with quenched QCD on a set of lattices with the same gauge background. Comparing the results of the lattice calculations in these two theories, the authors drew conclusions regarding the SU(6) valence quark model and chiral symmetry. While recognizing the goal of VQCD, Nathan Isgur disagrees on some of the conclusions the authors have drawn. The foremost objection raised in section 2 is to their suggestion that the major part of the hyperfine splittings in baryons is due to Goldstone boson exchange and not one-gluon-exchange (OGE) interactions. The logic of Isgur's objection is that VQCD yields a spectroscopy vastly different from quenched QCD and therefore the structure of the hadrons (to which hyperfine splittings in a quark model are intimately tied) is also suspect so no definite conclusions are possible. To put this into perspective it should be emphasized at the outset that spectroscopy is only one aspect of hadron physics examined in section 1. The authors have studied the axial and scalar couplings of nucleon in terms of F{sub A}/D{sub A} and F{sub S}/D{sub S}, the neutron to proton magnetic moment ratio {mu}n/{mu}p, and various form factors. None of these results reveal any pathologies of hadron structure and turn out to be close to the SU(6) relations, as expected. In fact this is what motivated the study of valence degrees of freedom via VQCD. In section 2 the authors address specific issues related to spectroscopy in VQCD. Isgur also presented more general arguments against the idea of boson exchange as a contributor to hyperfine effects. A cornerstone of his discussion is the unifying aspect of OGE in a

  18. QCD gluon vertices from the string-inspired formalism

    NASA Astrophysics Data System (ADS)

    Ahmadiniaz, Naser; Schubert, Christian

    2016-06-01

    The Bern-Kosower formalism, developed around 1990 as a novel way of obtaining QCD amplitudes as the limit of infinite string tension of the corresponding string amplitudes, was originally designed as an on-shell formalism. Building on early work by Strassler, the authors have recently shown that this “string-inspired formalism” is extremely efficient also as a tool for the study of off-shell amplitudes in QCD, and in particular for achieving compact form factor decompositions of the N-gluon vertices. Among other things, this formalism allows one to achieve a manifestly gauge invariant decomposition of these vertices by way of integration-by-parts, rather than the usual tedious analysis of the non-abelian off-shell Ward identities, and to combine the spin zero, half and one cases. Here, we will provide a summary of the method, as well as its application to the three- and four-gluon vertices.

  19. {eta} and {eta}{sup '} Mesons from Lattice QCD

    SciTech Connect

    Christ, N. H.; Liu, Q.; Mawhinney, R. D.; Dawson, C.; Izubuchi, T.; Jung, C.; Soni, A.; Sachrajda, C. T.; Zhou, R.

    2010-12-10

    The large mass of the ninth pseudoscalar meson, the {eta}{sup '}, is believed to arise from the combined effects of the axial anomaly and the gauge field topology present in QCD. We report a realistic, 2+1-flavor, lattice QCD calculation of the {eta} and {eta}{sup '} masses and mixing which confirms this picture. The physical eigenstates show small octet-singlet mixing with a mixing angle of {theta}=-14.1(2.8) deg. Extrapolation to the physical light quark mass gives, with statistical errors only, m{sub {eta}}=573(6) MeV and m{sub {eta}{sup '}}=947(142) MeV, consistent with the experimental values of 548 and 958 MeV.

  20. Localization and chiral symmetry in three flavor domain wall QCD

    SciTech Connect

    Antonio, David J.; Bowler, Kenneth C.; Boyle, Peter A.; Hart, Alistair; Kenway, Richard D.; Tweedie, Robert J.; Christ, Norman H.; Cohen, Saul D.; Li, Shu; Lin, Meifeng; Mawhinney, Robert D.; Clark, Michael A.; Dawson, Chris; Joo, Balint; Jung, Chulwoo; Maynard, Christopher M.; Ohta, Shigemi; Yamaguchi, Azusa

    2008-01-01

    We present results for the dependence of the residual mass of domain wall fermions on the size of the fifth dimension and its relation to the density and localization properties of low-lying eigenvectors of the corresponding Hermitian Wilson Dirac operator in three flavor domain wall QCD. Using the DBW2 and Iwasaki gauge actions, we generate ensembles of configurations with a 16{sup 3}x32 space-time volume and an extent of 8 in the fifth dimension for the sea quarks. We demonstrate the existence of a regime where the degree of locality, the size of chiral symmetry breaking, and the rate of topology change can be acceptable for inverse lattice spacings a{sup -1}{>=}1.6 GeV, enabling a programme of simulations of 2+1 flavor QCD to be conducted safely in this region of parameter space.

  1. Spontaneous supersymmetry breaking in two dimensional lattice super QCD

    DOE PAGES

    Catterall, Simon; Veernala, Aarti

    2015-10-02

    We report on a non-perturbative study of two dimensional N=(2,2) super QCD. Our lattice formulation retains a single exact supersymmetry at non-zero lattice spacing, and contains Nf fermions in the fundamental representation of a U(Nc) gauge group. The lattice action we employ contains an additional Fayet-Iliopoulos term which is also invariant under the exact lattice supersymmetry. This work constitutes the first numerical study of this theory which serves as a toy model for understanding some of the issues that are expected to arise in four dimensional super QCD. As a result, we present evidence that the exact supersymmetry breaks spontaneouslymore » when Nf < Nc in agreement with theoretical expectations.« less

  2. Spontaneous supersymmetry breaking in two dimensional lattice super QCD

    SciTech Connect

    Catterall, Simon; Veernala, Aarti

    2015-10-02

    We report on a non-perturbative study of two dimensional N=(2,2) super QCD. Our lattice formulation retains a single exact supersymmetry at non-zero lattice spacing, and contains Nf fermions in the fundamental representation of a U(Nc) gauge group. The lattice action we employ contains an additional Fayet-Iliopoulos term which is also invariant under the exact lattice supersymmetry. This work constitutes the first numerical study of this theory which serves as a toy model for understanding some of the issues that are expected to arise in four dimensional super QCD. As a result, we present evidence that the exact supersymmetry breaks spontaneously when Nf < Nc in agreement with theoretical expectations.

  3. Report of the 2005 Snowmass Top/QCD Working Group

    SciTech Connect

    Juste, A.; Kiyo, Y.; Petriello, F.; Teubner, T.; Agashe, K.; Batra, P.; Baur, U.; Berger, C.F.; Cembranos, J.A.R.; Gehrmann-De Ridder, A.; Gehrmann, T.; Glover, E.W.N.; Godfrey, S.; Hoang, A.; Perelstein, M.; Sullivan, Z.; Tait, T.; Zhu, S.; /Johns Hopkins U. /Princeton, Inst. Advanced Study /Syracuse U. /Argonne /SUNY, Buffalo /SLAC /UC, Irvine /Zurich, ETH /Zurich U. /Durham U., IPPP /Ottawa Carleton Inst. Phys. /Munich, Max Planck Inst. /Cornell U., CIHEP /Peking U.

    2006-01-17

    This report discusses several topics in both top quark physics and QCD at an International Linear Collider (ILC). Issues such as measurements at the t tbar threshold, including both theoretical and machine requirements, and the determination of electroweak top quark couplings are reviewed. New results concerning the potential of a 500 GeV e+e collider for measuring Wtb couplings and the top quark Yukawa coupling are presented. The status of higher order QCD corrections to jet production cross sections, heavy quark form factors, and longitudinal gauge boson scattering, needed for percent-level studies at the ILC, are reviewed. A new study of the measurement of the hadronic structure of the photon at a gamma gamma collider is presented. The effects on top quark properties from several models of new physics, including composite models, Little Higgs theories, and CPT violation, are studied.

  4. D-branes and coherent topological charge structure in QCD

    NASA Astrophysics Data System (ADS)

    Thacker, Hank

    2006-12-01

    Monte Carlo studies of pure glue SU(3) gauge theory using the overlap-based topological charge operator have revealed a laminar structure in the QCD vacuum consisting of extended, thin, co- herent, locally 3-dimensional sheets of topological charge embedded in 4D space, with opposite sign sheets interleaved. Studies of localization properties of Dirac eigenmodes have also shown evidence for the delocalization of low-lying modes on effectively 3-dimensional surfaces. In this talk, I review some theoretical ideas which suggest the possibility of 3-dimensionally coherent topological charge structure in 4-dimensional gauge theory and provide a possible interpretation of the observed structure. I begin with Luscher's "Wilson bag" integral over the 3-index Chern- Simons tensor. The analogy with a Wilson loop as a charged world line in 2-dimensional CP N-1 sigma models suggests that the Wilson bag surface represents the world volume of a physical membrane. The large-N chiral Lagrangian arguments of Witten also indicate the existence of multiple "k-vacuum" states with discontinuous transitions between k-vacua at θ = odd multi- ples of π. The domain walls between these vacua have the properties of a Wilson bag surface. Finally, I review the AdS/CFT duality view of θ dependence in QCD. The dual realtionship be- tween topological charge in gauge theory and Ramond-Ramond charge in type IIA string theory suggests that the coherent topological charge sheets observed on the lattice are the holographic image of wrapped D6 branes.

  5. The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.

    ERIC Educational Resources Information Center

    Francisco, E.; And Others

    1988-01-01

    Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

  6. The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.

    ERIC Educational Resources Information Center

    Francisco, E.; And Others

    1988-01-01

    Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

  7. QCD Measurements at ATLAS

    NASA Astrophysics Data System (ADS)

    Hubacek, Z.; Atlas Collaboration

    2017-07-01

    This paper presents recent QCD related measurements from the ATLAS Experiment at the LHC at CERN. The results on the total inelastic cross-section, charged particle production, jet production, photon production, and W -, Z -bosons productions are briefly summarized. The measurments are performed at different center-of-mass energies √{s}=7, 8, and 13 TeV . The measured cross-sections are generally found to be in agreement with the expectations from the Standard Model within the estimated uncertainties.

  8. Narrow pentaquarks in QCD

    SciTech Connect

    Navarra, F. S.; Nielsen, M.; Rodrigues da Silva, R.

    2006-02-11

    We study the decay {theta} {yields} K+n within the framework of QCD sum rules and compute the coupling g{theta}nK, which is directly related to the pentaquark width. Restricting the decay diagrams to those with color exchange between the meson-like and baryon-like clusters reduces the coupling constant by a factor of four. Whereas a small decay width might be possible for a positive parity pentaquark, it seems difficult to explain the measured width for a pentaquark with negative parity.

  9. QCD and strings

    SciTech Connect

    Sakai, Tadakatsu; Sugimoto, Shigeki

    2005-12-02

    We propose a holographic dual of QCD with massless flavors on the basis of a D4/D8-brane configuration within a probe approximation. We are led to a five-dimensional Yang-Mills theory on a curved space-time along with a Chern-Simons five-form on it, both of which provide us with a unifying framework to study the massless pion and an infinite number of massive vector mesons. We make sample computations of the physical quantities that involve the mesons and compare them with the experimental data. It is found that most of the results of this model are compatible with the experiments.

  10. Gauge fields in spintronics

    NASA Astrophysics Data System (ADS)

    Fujita, T.; Jalil, M. B. A.; Tan, S. G.; Murakami, S.

    2011-12-01

    We present an overview of gauge fields in spintronics, focusing on their origin and physical consequences. Important topics, such as the Berry gauge field associated with adiabatic quantum evolution as well as gauge fields arising from other non-adiabatic considerations, are discussed. We examine the appearance and effects of gauge fields across three spaces, namely real-space, momentum-space, and time, taking on a largely semiclassical approach. We seize the opportunity to study other "spin-like" systems, including graphene, topological insulators, magnonics, and photonics, which emphasize the ubiquity and importance of gauge fields. We aim to provide an intuitive and pedagogical insight into the role played by gauge fields in spin transport.

  11. Gauge symmetry from decoupling

    NASA Astrophysics Data System (ADS)

    Wetterich, C.

    2017-02-01

    Gauge symmetries emerge from a redundant description of the effective action for light degrees of freedom after the decoupling of heavy modes. This redundant description avoids the use of explicit constraints in configuration space. For non-linear constraints the gauge symmetries are non-linear. In a quantum field theory setting the gauge symmetries are local and can describe Yang-Mills theories or quantum gravity. We formulate gauge invariant fields that correspond to the non-linear light degrees of freedom. In the context of functional renormalization gauge symmetries can emerge if the flow generates or preserves large mass-like terms for the heavy degrees of freedom. They correspond to a particular form of gauge fixing terms in quantum field theories.

  12. Strain gauge installation tool

    DOEpatents

    Conard, L.M.

    1998-06-16

    A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.

  13. Closed String Tachyons, AdS/CFT, and QCD

    SciTech Connect

    Silverstein, Eva M

    2001-07-25

    We find that tachyonic orbifold examples of AdS/CFT have corresponding instabilities at small radius, and can decay to more generic gauge theories. We do this by computing a destabilizing Coleman-Weinberg effective potential for twisted operators of the corresponding quiver gauge theories, generalizing calculations of Tseytlin and Zarembo and interpreting them in terms of the large-N behavior of twisted-sector modes. The dynamically generated potential involves double-trace operators, which affect large-N correlators involving twisted fields but not those involving only untwisted fields, in line with large-N inheritance arguments. We point out a simple reason that no such small radius instability exists in gauge theories arising from freely acting orbifolds, which are tachyon-free at large radius. When an instability is present, twisted gauge theory operators with the quantum numbers of the large-radius tachyons acquire VEVs, leaving a gauge theory with fewer degrees of freedom in the infrared, analogous to but less extreme than ''decays to nothing'' studied in other systems with broken supersymmetry. In some cases one is left with pure glue QCD plus decoupled matter and U(1) factors in the IR, which we thus conjecture is described by the corresponding (possibly strongly coupled) endpoint of tachyon condensation in the M/String-theory dual.

  14. SUq( n) gauge theory

    NASA Astrophysics Data System (ADS)

    Sudbery, Anthony

    1996-02-01

    A field theory with local transformations belonging to the quantum group SUq( n) is defined on a classical spacetime, with gauge potentials belonging to a quantum Lie algebra. Gauge transformations are defined for the potentials which lead to the appropriate quantum-group transformations for field strengths and covariant derivatives, defined for all elements of SUq( n) by means of the adjoint action. This guarantees a non-trivial deformation. Gauge-invariant commutation relations are identified.

  15. High temperature pressure gauge

    DOEpatents

    Echtler, J. Paul; Scandrol, Roy O.

    1981-01-01

    A high temperature pressure gauge comprising a pressure gauge positioned in fluid communication with one end of a conduit which has a diaphragm mounted in its other end. The conduit is filled with a low melting metal alloy above the diaphragm for a portion of its length with a high temperature fluid being positioned in the remaining length of the conduit and in the pressure gauge.

  16. QCD and Supernovas

    NASA Astrophysics Data System (ADS)

    Barnes, T.

    2005-12-01

    In this contribution we briefly summarize aspects of the physics of QCD which are relevant to the supernova problem. The topic of greatest importance is the equation of state (EOS) of nuclear and strongly-interacting matter, which is required to describe the physics of the proto-neutron star (PNS) and the neutron star remnant (NSR) formed during a supernova event. Evaluation of the EOS in the regime of relevance for these systems, especially the NSR, requires detailed knowledge of the spectrum and strong interactions of hadrons of the accessible hadronic species, as well as other possible phases of strongly interacting matter, such as the quark-gluon plasma (QGP). The forces between pairs of baryons (both nonstrange and strange) are especially important in determining the EOS at NSR densities. Predictions for these forces are unfortunately rather model dependent where not constrained by data, and there are several suggestions for the QCD mechanism underlying these short-range hadronic interactions. The models most often employed for determining these strong interactions are broadly of two types, 1) meson exchange models (usually assumed in the existing neutron star and supernova literature), and 2) quark-gluon models (mainly encountered in the hadron, nuclear and heavy-ion literature). Here we will discuss the assumptions made in these models, and discuss how they are applied to the determination of hadronic forces that are relevant to the supernova problem.

  17. Tetraquarks in holographic QCD

    NASA Astrophysics Data System (ADS)

    Gutsche, Thomas; Lyubovitskij, Valery E.; Schmidt, Ivan

    2017-08-01

    Using a soft-wall AdS/QCD approach we derive the Schrödinger-type equation of motion for the tetraquark wave function, which is dual to the dimension-4 AdS bulk profile. The latter coincides with the number of constituents in the leading Fock state of the tetraquark. The obtained equation of motion is solved analytically, providing predictions for both the tetraquark wave function and its mass. A low mass limit for possible tetraquark states is given by M ≥2 κ =1 GeV , where κ =0.5 GeV is the typical value of the scale parameter in soft-wall AdS/QCD. We confirm results of the COMPASS Collaboration recently reported on the discovery of the a1(1414 ) state, interpreted as a tetraquark state composed of light quarks and having JP C=1++. Our prediction for the mass of this state, Ma1=√{2 } GeV ≃1.414 GeV , is in good agreement with the COMPASS result Ma1=1.41 4-0.013+0.015 GeV . Next we included finite quark mass effects, which are essential for the tetraquark states involving heavy quarks.

  18. Hybrid baryons in QCD

    DOE PAGES

    Dudek, Jozef J.; Edwards, Robert G.

    2012-03-21

    In this study, we present the first comprehensive study of hybrid baryons using lattice QCD methods. Using a large basis of composite QCD interpolating fields we extract an extensive spectrum of baryon states and isolate those of hybrid character using their relatively large overlap onto operators which sample gluonic excitations. We consider the spectrum of Nucleon and Delta states at several quark masses finding a set of positive parity hybrid baryons with quantum numbersmore » $$N_{1/2^+},\\,N_{1/2^+},\\,N_{3/2^+},\\, N_{3/2^+},\\,N_{5/2^+},\\,$$ and $$\\Delta_{1/2^+},\\, \\Delta_{3/2^+}$$ at an energy scale above the first band of `conventional' excited positive parity baryons. This pattern of states is compatible with a color octet gluonic excitation having $$J^{P}=1^{+}$$ as previously reported in the hybrid meson sector and with a comparable energy scale for the excitation, suggesting a common bound-state construction for hybrid mesons and baryons.« less

  19. Novel Spin Effects in QCD

    SciTech Connect

    Brodsky, S

    2004-01-15

    Measurements from HERMES, SMC, and Jlab show a significant single-spin asymmetry in semi-inclusive pion leptoproduction {gamma}*(q)p {yields} {pi}X when the proton is polarized normal to the photon-to-pion production plane. Hwang, Schmidt, and I [1] have shown that final-state interactions from gluon exchange between the outgoing quark and the target spectator system lead to such single-spin asymmetries at leading twist in perturbative QCD; i.e., the rescattering corrections are not power-law suppressed at large photon virtuality Q{sup 2} at fixed x{sub bj}. The existence of such single-spin asymmetries (the Sivers effect) requires a phase difference between two amplitudes coupling the proton target with J{sub p}{sup z} = {+-} 1/2 to the same final-state, the same amplitudes which are necessary to produce a nonzero proton anomalous magnetic moment. The single-spin asymmetry which arises from such final-state interactions is in addition to the Collins effect which measures the transversity distribution {delta}q(x, Q). The Sivers effect also leads to a leading-twist target single-spin asymmetry for jet production in electroproduction where the thrust axis is used to define the production plane. More generally, Hoyer, Marchal, Peigne, Sannino, and I [2] have shown that one cannot neglect the interactions which occur between the times of the currents in the current correlator even in light-cone gauge. For example, the final-state interactions lead to the Bjorken-scaling diffractive component {gamma}*p {yields} pX of deep inelastic scattering. Since the gluons exchanged in the final state carry negligible k{sup +}, the Pomeron structure function closely resembles that of the primary gluon. The diffractive scattering of the fast outgoing quarks on spectators in the target in turn causes shadowing in the DIS cross section. These effects highlight the unexpected importance of final- and initial-state interactions in QCD observables, they lead to leading-twist single

  20. Implementing general gauge mediation

    SciTech Connect

    Carpenter, Linda M.; Dine, Michael; Festuccia, Guido; Mason, John D.

    2009-02-01

    Recently there has been much progress in building models of gauge mediation, often with predictions different than those of minimal gauge mediation. Meade, Seiberg, and Shih have characterized the most general spectrum which can arise in gauge-mediated models. We discuss some of the challenges of building models of general gauge mediation, especially the problem of messenger parity and issues connected with R symmetry breaking and CP violation. We build a variety of viable, weakly coupled models which exhibit some or all of the possible low energy parameters.

  1. Discrete Gauge Theories

    NASA Astrophysics Data System (ADS)

    Alford, Mark G.; March-Russell, John

    In this review we discuss the formulation and distinguishing characteristics of discrete gauge theories, and describe several important applications of the concept. For the abelian (ℤN) discrete gauge theories, we consider the construction of the discrete charge operator F(Σ*) and the associated gauge-invariant order parameter that distinguishes different Higgs phases of a spontaneously broken U(1) gauge theory. We sketch some of the important thermodynamic consequences of the resultant discrete quantum hair on black holes. We further show that, as a consequence of unbroken discrete gauge symmetries, Grand Unified cosmic strings generically exhibit a Callan-Rubakov effect. For non-abelian discrete gauge theories we discuss in some detail the charge measurement process, and in the context of a lattice formulation we construct the non-abelian generalization of F(Σ*). This enables us to build the order parameter that distinguishes the different Higgs phases of a non-abelian discrete lattice gauge theory with matter. We also describe some of the fascinating phenomena associated with non-abelian gauge vortices. For example, we argue that a loop of Alice string, or any non-abelian string, is super-conducting by virtue of charged zero modes whose charge cannot be localized anywhere on or around the string (“Cheshire charge”). Finally, we discuss the relationship between discrete gauge theories and the existence of excitations possessing exotic spin and statistics (and more generally excitations whose interactions are purely “topological”).

  2. Singlet-stabilized minimal gauge mediation

    SciTech Connect

    Curtin, David; Tsai, Yuhsin

    2011-04-01

    We propose singlet-stabilized minimal gauge mediation as a simple Intriligator, Seiberg and Shih-based model of direct gauge mediation which avoids both light gauginos and Landau poles. The hidden sector is a massive s-confining supersymmetric QCD that is distinguished by a minimal SU(5) flavor group. The uplifted vacuum is stabilized by coupling the meson to an additional singlet sector with its own U(1) gauge symmetry via nonrenormalizable interactions suppressed by a higher scale {Lambda}{sub UV} in the electric theory. This generates a nonzero vacuum expectation value for the singlet meson via the inverted hierarchy mechanism, but requires tuning to a precision {approx}({Lambda}/{Lambda}{sub UV}){sup 2}, which is {approx}10{sup -4}. In the course of this analysis we also outline some simple model-building rules for stabilizing uplifted-ISS models, which lead us to conclude that meson deformations are required (or at least heavily favored) to stabilize the adjoint component of the magnetic meson.

  3. Light-Front Quantization of Gauge Theories

    SciTech Connect

    Brodskey, Stanley

    2002-12-01

    Light-front wavefunctions provide a frame-independent representation of hadrons in terms of their physical quark and gluon degrees of freedom. The light-front Hamiltonian formalism provides new nonperturbative methods for obtaining the QCD spectrum and eigensolutions, including resolvant methods, variational techniques, and discretized light-front quantization. A new method for quantizing gauge theories in light-cone gauge using Dirac brackets to implement constraints is presented. In the case of the electroweak theory, this method of light-front quantization leads to a unitary and renormalizable theory of massive gauge particles, automatically incorporating the Lorentz and 't Hooft conditions as well as the Goldstone boson equivalence theorem. Spontaneous symmetry breaking is represented by the appearance of zero modes of the Higgs field leaving the light-front vacuum equal to the perturbative vacuum. I also discuss an ''event amplitude generator'' for automatically computing renormalized amplitudes in perturbation theory. The importance of final-state interactions for the interpretation of diffraction, shadowing, and single-spin asymmetries in inclusive reactions such as deep inelastic lepton-hadron scattering is emphasized.

  4. Singlet-stabilized minimal gauge mediation

    NASA Astrophysics Data System (ADS)

    Curtin, David; Tsai, Yuhsin

    2011-04-01

    We propose singlet-stabilized minimal gauge mediation as a simple Intriligator, Seiberg and Shih-based model of direct gauge mediation which avoids both light gauginos and Landau poles. The hidden sector is a massive s-confining supersymmetric QCD that is distinguished by a minimal SU(5) flavor group. The uplifted vacuum is stabilized by coupling the meson to an additional singlet sector with its own U(1) gauge symmetry via nonrenormalizable interactions suppressed by a higher scale ΛUV in the electric theory. This generates a nonzero vacuum expectation value for the singlet meson via the inverted hierarchy mechanism, but requires tuning to a precision ˜(Λ/ΛUV)2, which is ˜10-4. In the course of this analysis we also outline some simple model-building rules for stabilizing uplifted-ISS models, which lead us to conclude that meson deformations are required (or at least heavily favored) to stabilize the adjoint component of the magnetic meson.

  5. RIKEN BNL RESEARCH CENTER WORKSHOP ON GAUGE-INVARIANT VARIABLES IN GAUGE THEORIES, VOLUME 20

    SciTech Connect

    VAN BAAL,P.; ORLAND,P.; PISARSKI,R.

    2000-06-01

    This four-day workshop focused on the wide variety of approaches to the non-perturbative physics of QCD. The main topic was the formulation of non-Abelian gauge theory in orbit space, but some other ideas were discussed, in particular the possible extension of the Maldacena conjecture to nonsupersymmetric gauge theories. The idea was to involve most of the participants in general discussions on the problem. Panel discussions were organized to further encourage debate and understanding. Most of the talks roughly fell into three categories: (1) Variational methods in field theory; (2) Anti-de Sitter space ideas; (3) The fundamental domain, gauge fixing, Gribov copies and topological objects (both in the continuum and on a lattice). In particular some remarkable progress in three-dimensional gauge theories was presented, from the analytic side by V.P. Nair and mostly from the numerical side by O. Philipsen. This work may ultimately have important implications for RHIC experiments on the high-temperature quark-gluon plasma.

  6. The Gauge-Field Propagator in Light-Cone Gauge: Which is the Correct One?

    NASA Astrophysics Data System (ADS)

    Mantovani, L.; Bacchetta, A.; Pasquini, B.; Xiong, X.

    2017-03-01

    In the literature one can find two different expressions for the gauge-field propagator in light-cone gauge, containing the sum of three rather than two terms. The question of which of the two is the correct one has been a subject of debate. We propose a solution to this question by evaluating one-loop level processes in QED, both in the covariant approach in the light-cone gauge and in the light-front time-ordered perturbation theory (TOPT) approach, proving the equivalence between the two formulations of the theory. The form of the propagator turns out to be crucial in the proof, in particular as concerns its relation with the diagrams containing instantaneously propagating photons and instantaneous interactions. We show that the diagrams in light-front TOPT with instantaneous photons can be recovered in the covariant approach starting from the propagators with only two terms. Our proof of the equivalence clarifies which form should be used for the gauge-field propagator in the covariant approach. This result naturally applies to the QCD case also.

  7. The K+ K+ scattering length from Lattice QCD

    SciTech Connect

    Silas Beane; Thomas Luu; Konstantinos Orginos; Assumpta Parreno; Martin Savage; Aaron Torok; Andre Walker-Loud

    2007-09-11

    The K+K+ scattering length is calculated in fully-dynamical lattice QCD with domain-wall valence quarks on the MILC asqtad-improved gauge configurations with fourth-rooted staggered sea quarks. Three-flavor mixed-action chiral perturbation theory at next-to-leading order, which includes the leading effects of the finite lattice spacing, is used to extrapolate the results of the lattice calculation to the physical value of mK + /fK + . We find mK^+ aK^+ K^+ = â~0.352 ± 0.016, where the statistical and systematic errors have been combined in quadrature.

  8. Charmed meson decay constants in three-flavor lattice QCD

    SciTech Connect

    Aubin, C.; Bernard, C.; DeTar, C.; Di Pierro, M.; Freeland, Elizabeth D.; Gottlieb, Steven; Heller, U.M.; Hetrick, J.E.; El-Khadra, Aida X.; Kronfeld, Andreas S.; Levkova, L.; Mackenzie, P.B.; Menscher, D.; Maresca, F.; Nobes, M.; Okamoto, M.; Renner, D.B.; Simone, J.; Sugar, R.; Toussaint, D.; Trottier, H.D.; /Art Inst. of Chicago /Columbia U. /Washington U., St. Louis /Utah U. /DePaul U. /Indiana U. /APS, New York /U. Pacific, Stockton /Illinois U., Urbana /Fermilab /Cornell U., LEPP /Arizona U. /UC, Santa Barbara /Simon Fraser U.

    2005-06-01

    The authors present the first lattice QCD calculation with realistic sea quark content of the D{sup +}-meson decay constant f{sub D+}. They use the MILC Collaboration's publicly available ensembles of lattice gauge fields, which have a quark sea with two flavors (up and down) much lighter than a third (strange). They obtain f{sub D+} = 201 {+-} 3 {+-} 17 MeV, where the errors are statistical and a combination of systematic errors. They also obtain f{sub D{sub s}} = 249 {+-} 3 {+-} 16 MeV for the D{sub s} meson.

  9. Hyperon-Nulceon Scattering from Fully-Dynamical Lattice QCD

    SciTech Connect

    Silas Beane; Paulo Bedaque; Thomas Luu; Konstantinos Orginos; Elizabetta Pallante; Assumpta Parreno; Martin Savage

    2007-10-01

    We present results of the first fully-dynamical lattice QCD determination of hyperon-nucleon scattering. One s-wave phase shift was determined for n{Lambda} scattering in both spin-channels at pion masses of 350, 490, and 590 MeV, and for n{Sigma}^- scattering in both spin channels at pion masses of 490, and 590 MeV. The calculations were performed with domain-wall valence quarks on dynamical, staggered gauge configurations with a lattice spacing of b ~0.125 fm.

  10. Exploring quark transverse momentum distributions with lattice QCD

    SciTech Connect

    Bernhard U. Musch, Philipp Hagler, John W. Negele, Andreas Schafer

    2011-05-01

    We discuss in detail a method to study transverse momentum dependent parton distribution functions (TMDs) using lattice QCD. To develop the formalism and to obtain first numerical results, we directly implement a bi-local quark-quark operator connected by a straight Wilson line, allowing us to study T-even, "process-independent" TMDs. Beyond results for x-integrated TMDs and quark densities, we present a study of correlations in x and transverse momentum. Our calculations are based on domain wall valence quark propagators by the LHP collaboration calculated on top of gauge configurations provided by MILC with 2+1 flavors of asqtad-improved staggered sea quarks.

  11. Group theoretical construction of extended baryon operators in lattice QCD

    SciTech Connect

    Subhasish Basak; Robert Edwards; George Fleming; Urs Heller; Colin Morningstar; David Richards; Ikuro Sato; Stephen Wallace

    2005-06-01

    The design and implementation of large sets of spatially-extended, gauge-invariant operators for use in determining the spectrum of baryons in lattice QCD computations are described. Group theoretical projections onto the irreducible representations of the symmetry group of a cubic spatial lattice are used in all isospin channels. The operators are constructed to maximize overlaps with the low-lying states of interest, while minimizing the number of sources needed in computing the required quark propagators. Issues related to the identification of the spin quantum numbers of the states in the continuum limit are addressed.

  12. Single-Sector Supersymmetry Breaking in Supersymmetric QCD

    SciTech Connect

    Franco, Sebastian; Kachru, Shamit; /Santa Barbara, KITP /UC, Santa Barbara /Stanford U., Phys. Dept. /SLAC

    2010-08-26

    We construct examples of single-sector supersymmetry breaking based on simple deformations of supersymmetric QCD with (weakly) gauged flavor group. These theories are calculable in a weakly coupled Seiberg dual description. In these models, some of the particles in the first two generations of quarks and leptons are composites of the same strong dynamics which leads to dynamical supersymmetry breaking. Such models can explain the hierarchies of Yukawa couplings in the Standard Model, in a way that predictively correlates with the spectrum of SUSY-breaking soft terms.

  13. Full lattice QCD study of the κ scalar meson

    NASA Astrophysics Data System (ADS)

    Fu, Zi-Wen; Carleton, DeTar

    2011-12-01

    We studied the κ light scalar meson in 2+1 flavor full QCD with sufficiently light u and d quarks. Via lattice simulation we measured the correlators for the κ channel in the “Asqtad" improved staggered fermion formulation. After chiral extrapolation we obtained the mass of the κ meson with 826 ± 119 MeV, which is within recent experimental values of 800-900 MeV. The simulations were carried out with the MILC 2+1 flavor gauge configurations at lattice spacing a≈0.15 fm.

  14. Viscous quark-gluon plasma model through fluid QCD approach

    SciTech Connect

    Djun, T. P.; Soegijono, B.; Mart, T.; Handoko, L. T. E-mail: Laksana.tri.handoko@lipi.go.id

    2014-09-25

    A Lagrangian density for viscous quark-gluon plasma has been constructed within the fluid-like QCD framework. Gauge symmetry is preserved for all terms inside the Lagrangian, except for the viscous term. The transition mechanism from point particle field to fluid field, and vice versa, are discussed. The energy momentum tensor that is relevant to the gluonic plasma having the nature of fluid bulk of gluon sea is derived within the model. By imposing conservation law in the energy momentum tensor, shear viscosity appears as extractable from the equation.

  15. Fluctuations of conserved charges at finite temperature from lattice QCD

    NASA Astrophysics Data System (ADS)

    Borsányi, Szabolcs; Fodor, Zoltán; Katz, Sándor D.; Krieg, Stefan; Ratti, Claudia; Szabó, Kálman

    2012-01-01

    We present the full results of the Wuppertal-Budapest lattice QCD collaboration on flavor diagonal and non-diagonal quark number susceptibilities with 2 + 1 staggered quark flavors, in a temperature range between 125 and 400 MeV. The light and strange quark masses are set to their physical values. Lattices with N t = 6, 8, 10, 12, 16 are used. We perform a continuum extrapolation of all observables under study. A Symanzik improved gauge and a stout-link improved staggered fermion action is utilized. All results are compared to the Hadron Resonance Gas model predictions: good agreement is found in the temperature region below the transition.

  16. Chiral logarithms in quenched QCD

    SciTech Connect

    Y. Chen; S. J. Dong; T. Draper; I. Horvath; F. X. Lee; K. F. Liu; N. Mathur; and J. B. Zhang

    2004-08-01

    The quenched chiral logarithms are examined on a 163x28 lattice with Iwasaki gauge action and overlap fermions. The pion decay constant fpi is used to set the lattice spacing, a = 0.200(3) fm. With pion mass as low as {approx}180 MeV, we see the quenched chiral logarithms clearly in mpi2/m and fP, the pseudoscalar decay constant. The authors analyze the data to determine how low the pion mass needs to be in order for the quenched one-loop chiral perturbation theory (chiPT) to apply. With the constrained curve-fitting method, they are able to extract the quenched chiral logarithmic parameter delta together with other low-energy parameters. Only for mpi<=300 MeV do we obtain a consistent and stable fit with a constant delta which they determine to be 0.24(3)(4) (at the chiral scale Lambdachi = 0.8 GeV). By comparing to the 123x28 lattice, they estimate the finite volume effect to be about 2.7% for the smallest pion mass. They also fitted the pion mass to the form for the re-summed cactus diagrams and found that its applicable region is extended farther than the range for the one-loop formula, perhaps up to mpi {approx}500-600 MeV. The scale independent delta is determined to be 0.20(3) in this case. The authors study the quenched non-analytic terms in the nucleon mass and find that the coefficient C1/2 in the nucleon mass is consistent with the prediction of one-loop chiPT. They also obtain the low energy constant L5 from fpi. They conclude from this study that it is imperative to cover only the range of data with the pion mass less than {approx}300 MeV in order to examine the chiral behavior of the hadron masses and decay constants in quenched QCD and match them with quenched one-loop chiPT.

  17. Lattice QCD and Nuclear Physics

    SciTech Connect

    Konstantinos Orginos

    2007-03-01

    A steady stream of developments in Lattice QCD have made it possible today to begin to address the question of how nuclear physics emerges from the underlying theory of strong interactions. Central role in this understanding play both the effective field theory description of nuclear forces and the ability to perform accurate non-perturbative calculations in lo w energy QCD. Here I present some recent results that attempt to extract important low energy constants of the effective field theory of nuclear forces from lattice QCD.

  18. Theta angle in holographic QCD

    NASA Astrophysics Data System (ADS)

    Järvinen, Matti

    2017-03-01

    V-QCD is a class of effective holographic models for QCD which fully includes the backreaction of quarks to gluon dynamics. The physics of the θ-angle and the axial anomaly can be consistently included in these models. We analyze their phase diagrams over ranges of values of the quark mass, Nf/Nc, and θ, computing observables such as the topological susceptibility and the meson masses. At small quark mass, where effective chiral Lagrangians are reliable, they agree with the predictions of V-QCD.

  19. The QCD equation of state with charm quarks from lattice QCD

    NASA Astrophysics Data System (ADS)

    Cheng, Michael

    Recently, there have been several calculations of the QCD equation of state (EoS) on the lattice. These calculations take into account the two light quarks and the strange quark, but have ignored the effects of the charm quark, assuming that the charm mass (mc ≈ 1300 MeV) is exponentially suppressed at the temperatures which are explored. However, future heavy ion collisions, such as those planned at the LHC, may well probe temperature regimes where the charm quarks play an important role in the dynamics of the QGP. We present a calculation of the charm quark contribution to the QCD EoS using p4-improved staggered fermions at Nt = 4, 6, 8. This calculation is done with a quenched charm quark, i.e. the relevant operators are measured using a valence charm quark mass on a 2+1 flavor gauge field background. The charm quark masses are determined by calculating charmonium masses (metac and mJ/Psi) and fixing these mesons to their physical masses. The interaction measure, pressure, energy density, and entropy density are calculated. We find that the charm contribution makes a significant contribution, even down to temperatures as low as the pseudo-critical temperature, Tc. However, there are significant scaling corrections at the lattice spacings that we use, preventing a reliable continuum extrapolation.

  20. Rain Gauges Handbook

    SciTech Connect

    Bartholomew, M. J.

    2016-01-01

    To improve the quantitative description of precipitation processes in climate models, the Atmospheric Radiation Measurement (ARM) Climate Research Facility deployed rain gauges located near disdrometers (DISD and VDIS data streams). This handbook deals specifically with the rain gauges that make the observations for the RAIN data stream. Other precipitation observations are made by the surface meteorology instrument suite (i.e., MET data stream).

  1. Crystallization in two-component Coulomb systems.

    PubMed

    Bonitz, M; Filinov, V S; Fortov, V E; Levashov, P R; Fehske, H

    2005-12-02

    The analysis of Coulomb crystallization is extended from one-component to two-component plasmas. Critical parameters for the existence of Coulomb crystals are derived for both classical and quantum crystals. In the latter case, a critical mass ratio of the two charged components is found, which is of the order of 80. Thus, holes in semiconductors with sufficiently flat valence bands are predicted to spontaneously order into a regular lattice. Such hole crystals are intimately related to ion Coulomb crystals in white dwarf and neutron stars as well as to ion crystals produced in the laboratory. A unified phase diagram of two-component Coulomb crystals is presented and is verified by first-principles computer simulations.

  2. Analytic form for the nonrelativistic Coulomb propagator

    NASA Astrophysics Data System (ADS)

    Blinder, S. M.

    1991-01-01

    An analytic form for the nonrelativistic Coulomb propagator is derived, thus resolving a long-standing problem in Feynman's path-integral formulation of quantum mechanics. Hostler's formula for the Coulomb Green's function is expanded according to the theorem of Mittag-Leffler, then Fourier transformed term by term to give the Coulomb propagator. The result is a discrete summation over the principal quantum number n, involving Whittaker, Laguerre, Hermite, and error functions. As is the case for other nonquadratic potentials, the Coulomb propagator does not have the canonical structure K=F exp(iS/ħ). Part of the expansion resembles a form derived by Crandall [J. Phys. A 16, 3005 (1983)] for the case of reflectionless potentials.

  3. The Symmetries of QCD

    ScienceCinema

    Sekhar Chivukula

    2016-07-12

    The symmetries of a quantum field theory can be realized in a variety of ways. Symmetries can be realized explicitly, approximately, through spontaneous symmetry breaking or, via an anomaly, quantum effects can dynamically eliminate a symmetry of the theory that was present at the classical level.  Quantum Chromodynamics (QCD), the modern theory of the strong interactions, exemplify each of these possibilities. The interplay of these effects determine the spectrum of particles that we observe and, ultimately, account for 99% of the mass of ordinary matter. 

  4. Recent developments in Coulomb breakup calculations

    SciTech Connect

    Capel, P.

    2008-05-12

    The theory of reactions applied to Coulomb breakup of loosely-bound projectiles is reviewed. Both the Continuum Discretized Coupled Channel (CDCC) and time-dependent models are described. Recent results about sensitivity of breakup calculations to the projectile wave function are reviewed. Analyses of the extraction of radiative-capture cross section from Coulomb breakup measurements are presented. Current developments in breakup theory are also mentioned.

  5. Transient anomalous charge production in strong-field QCD

    NASA Astrophysics Data System (ADS)

    Tanji, Naoto; Mueller, Niklas; Berges, Jürgen

    2016-04-01

    We investigate axial charge production in two-color QCD out of equilibrium. We compute the real-time evolution starting with spatially homogeneous strong gauge fields, while the fermions are in vacuum. The idealized class of initial conditions is motivated by glasma flux tubes in the context of heavy-ion collisions. We focus on axial charge production at early times, where important aspects of the anomalous dynamics can be derived analytically. This is compared to real-time lattice simulations. Quark production at early times leading to anomalous charge generation is investigated using Wilson fermions. Our results indicate that coherent gauge fields can transiently produce significant amounts of axial charge density, while part of the induced charges persist to be present even well beyond characteristic decoherence times. The comparisons to analytic results provide stringent tests of real-time representations of the axial anomaly on the lattice.

  6. Asymmetric dark matter and the hadronic spectra of hidden QCD

    NASA Astrophysics Data System (ADS)

    Lonsdale, Stephen J.; Schroor, Martine; Volkas, Raymond R.

    2017-09-01

    The idea that dark matter may be a composite state of a hidden non-Abelian gauge sector has received great attention in recent years. Frameworks such as asymmetric dark matter motivate the idea that dark matter may have similar mass to the proton, while mirror matter and G ×G grand unified theories provide rationales for additional gauge sectors which may have minimal interactions with standard model particles. In this work we explore the hadronic spectra that these dark QCD models can allow. The effects of the number of light colored particles and the value of the confinement scale on the lightest stable state, the dark matter candidate, are examined in the hyperspherical constituent quark model for baryonic and mesonic states.

  7. Vertex Sensitivity in the Schwinger-Dyson Equations of QCD

    SciTech Connect

    David J. Wilson, Michael R. Pennington

    2012-01-01

    The nonperturbative gluon and ghost propagators in Landau gauge QCD are obtained using the Schwinger-Dyson equation approach. The propagator equations are solved in Euclidean space using Landau gauge with a range of vertex inputs. Initially we solve for the ghost alone, using a model gluon input, which leads us to favour a finite ghost dressing in the nonperturbative region. In order to then solve the gluon and ghost equations simultaneously, we find that non-trivial vertices are required, particularly for the gluon propagator in the small momentum limit. We focus on the properties of a number vertices and how these differences influence the final solutions. The self-consistent solutions we obtain are all qualitatively similar and contain a mass-like term in the gluon propagator dressing in agreement with related studies, supporting the long-held proposal of Cornwall.

  8. Off-shell Jost solutions for Coulomb and Coulomb-like interactions in all partial waves

    SciTech Connect

    Laha, U.; Bhoi, J.

    2013-01-15

    By exploiting the theory of ordinary differential equations, with judicious use of boundary conditions, interacting Green's functions and their integral transforms together with certain properties of higher transcendental functions, useful analytical expressions for the off-shell Jost solutions for motion in Coulomb and Coulomb-nuclear potentials are derived in maximal reduced form through different approaches to the problem in the representation space. The exact analytical expressions for the off-shell Jost solutions for Coulomb and Coulomb-like potentials are believed to be useful for the description of the charged particle scattering/reaction processes.

  9. Highly effective action from large N gauge fields

    NASA Astrophysics Data System (ADS)

    Yang, Hyun Seok

    2014-10-01

    Recently Schwarz put forward a conjecture that the world-volume action of a probe D3-brane in an AdS5×S5 background of type IIB superstring theory can be reinterpreted as the highly effective action (HEA) of four-dimensional N =4 superconformal field theory on the Coulomb branch. We argue that the HEA can be derived from the noncommutative (NC) field theory representation of the AdS/CFT correspondence and the Seiberg-Witten (SW) map defining a spacetime field redefinition between ordinary and NC gauge fields. It is based only on the well-known facts that the master fields of large N matrices are higher-dimensional NC U(1) gauge fields and the SW map is a local coordinate transformation eliminating U(1) gauge fields known as the Darboux theorem in symplectic geometry.

  10. Parallel Molecular Dynamics of Coulomb Clusters

    NASA Astrophysics Data System (ADS)

    Kishimoto, Tokunari; Totsuji, Chieko; Tsuruta, Kenji; Totsuji, Hiroo

    2000-10-01

    Using parallel computers, we perform large-scale molecular dynamics (MD) simulations of Coulomb clusters in a spherical trapping field. Long-range Coulomb forces are calculated efficiently using the fast multipole method (FMM). Previously Hasse and Avilov [1] have performed numerical analysis of Coulomb clusters, and predicted a crossover between the energy curve of Coulomb clusters and that of finite bcc crystals around N = 10^6. Another prediction [2] has been reported around N = 10^5. Recently, experimental observation of Be^+ clusters in ion trap [3] indicated that structure of N = 8 *10^4 was similar to bcc single crystal. We perform direct simulations of Coulomb clusters of system sizes N = 10^5-10^6. We report preliminary results on 10^5 system: Radial distribution and the Laue-pattern analysis indicates structural evolution of the cluster. The correlation energy of the cluster is found to be lower than finite bcc crystal of the same size. We will show results for larger systems (10^6) and the N dependence of structure and energy of the Coulomb clusters around the crossover region. [1] R. W. Hasse and V. V. Avilov, Phys. Rev. A 44, 4506 (1991). [2] D. H. E. Dubin, Phys. Rev. A 40, 1140 (1989). [3] W. M. Itano et al., Science 279, 686 (1998).

  11. LATTICE QCD AT FINITE TEMPERATURE.

    SciTech Connect

    PETRECZKY, P.

    2005-03-12

    I review recent progress in lattice QCD at finite temperature. Results on the transition temperature will be summarized. Recent progress in understanding in-medium modifications of interquark forces and quarkonia spectral functions at finite temperatures is discussed.

  12. Excited Baryons in Holographic QCD

    SciTech Connect

    de Teramond, Guy F.; Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins

    2011-11-08

    The light-front holographic QCD approach is used to describe baryon spectroscopy and the systematics of nucleon transition form factors. Baryon spectroscopy and the excitation dynamics of nucleon resonances encoded in the nucleon transition form factors can provide fundamental insight into the strong-coupling dynamics of QCD. The transition from the hard-scattering perturbative domain to the non-perturbative region is sensitive to the detailed dynamics of confined quarks and gluons. Computations of such phenomena from first principles in QCD are clearly very challenging. The most successful theoretical approach thus far has been to quantize QCD on discrete lattices in Euclidean space-time; however, dynamical observables in Minkowski space-time, such as the time-like hadronic form factors are not amenable to Euclidean numerical lattice computations.

  13. Coulomb's law corrections and fermion field localization in a tachyonic de Sitter thick braneworld

    NASA Astrophysics Data System (ADS)

    Cartas-Fuentevilla, Roberto; Escalante, Alberto; Germán, Gabriel; Herrera-Aguilar, Alfredo; Rigel Mora-Luna, Refugio

    2016-05-01

    Following recent studies which show that it is possible to localize gravity as well as scalar and gauge vector fields in a tachyonic de Sitter thick braneworld, we investigate the solution of the gauge hierarchy problem, the localization of fermion fields in this model, the recovering of the Coulomb law on the non-relativistic limit of the Yukawa interaction between bulk fermions and gauge bosons localized in the brane, and confront the predicted 5D corrections to the photon mass with its upper experimental/observational bounds, finding the model physically viable since it passes these tests. In order to achieve the latter aims we first consider the Yukawa interaction term between the fermionic and the tachyonic scalar fields MF(T)ΨΨ̅ in the action and analyze four distinct tachyonic functions F(T) that lead to four different structures of the respective fermionic mass spectra with different physics. In particular, localization of the massless left-chiral fermion zero mode is possible for three of these cases. We further analyze the phenomenology of these Yukawa interactions among fermion fields and gauge bosons localized on the brane and obtain the crucial and necessary information to compute the corrections to Coulomb's law coming from massive KK vector modes in the non-relativistic limit. These corrections are exponentially suppressed due to the presence of the mass gap in the mass spectrum of the bulk gauge vector field. From our results we conclude that corrections to Coulomb's law in the thin brane limit have the same form (up to a numerical factor) as far as the left-chiral massless fermion field is localized on the brane. Finally we compute the corrections to the Coulomb's law for an arbitrarily thick brane scenario which can be interpreted as 5D corrections to the photon mass. By performing consistent estimations with brane phenomenology, we found that the predicted corrections to the photon mass, which are well bounded by the experimentally observed or

  14. A Unitary and Renormalizable Theory of the Standard Model in Ghost-Free Light-Cone Gauge

    SciTech Connect

    Brodsky, Stanley J.

    2002-02-15

    Light-front (LF) quantization in light-cone (LC) gauge is used to construct a unitary and simultaneously renormalizable theory of the Standard Model. The framework derived earlier for QCD is extended to the Glashow, Weinberg, and Salam (GWS) model of electroweak interaction theory. The Lorentz condition is automatically satisfied in LF-quantized QCD in the LC gauge for the free massless gauge field. In the GWS model, with the spontaneous symmetry breaking present, we find that the 't Hooft condition accompanies the LC gauge condition corresponding to the massive vector boson. The two transverse polarization vectors for the massive vector boson may be chosen to be the same as found in QCD. The non-transverse and linearly independent third polarization vector is found to be parallel to the gauge direction. The corresponding sum over polarizations in the Standard model, indicated by K{sub {mu}{nu}}(k); has several simplifying properties similar to the polarization sum D{sub {mu}{nu}}(k) in QCD. The framework is ghost-free, and the interaction Hamiltonian of electroweak theory can be expressed in a form resembling that of covariant theory, except for few additional instantaneous interactions which can be treated systematically. The LF formulation also provides a transparent discussion of the Goldstone Boson (or Electroweak) Equivalence Theorem, as the illustrations show.

  15. Approximate Coulomb distortion effects in (e,e{sup {prime}}p) reactions

    SciTech Connect

    Kim, K.S.; Wright, L.E.

    1997-07-01

    In this paper we apply a well-tested approximation of electron Coulomb distortion effects to the exclusive reaction (e,e{sup {prime}}p) in the quasielastic region. We compare the approximate treatment of Coulomb distortion effects to the exact distorted wave Born approximation evaluated by means of partial wave analysis to gauge the quality of our approximate treatment. We show that the approximate Mo/ller potential has a plane-wave-like structure and hence permits the separation of the cross section into five terms which depend on bilinear products of transforms of the transition four current elements. These transforms reduce to Fourier transforms when Coulomb distortion is not present, but become modified with the inclusion of Coulomb distortion. We investigate the application of the approximate formalism to a model of {sup 208}Pb(e,e{sup {prime}}p) using Dirac-Hartree single particle wave functions for the ground state and relativistic optical model wave functions for the continuum proton. We show that it is still possible to extract, albeit with some approximation, the various structure functions from the experimentally measured data even for heavy nuclei. {copyright} {ital 1997} {ital The American Physical Society}

  16. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MaCarthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  17. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  18. Optical heat flux gauge

    DOEpatents

    Noel, Bruce W.; Borella, Henry M.; Cates, Michael R.; Turley, W. Dale; MacArthur, Charles D.; Cala, Gregory C.

    1991-01-01

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises a plurality of respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  19. Optical heat flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

    1991-06-25

    A heat flux gauge is described comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator wherein each thermographic layer comprises respective thermographic phosphors. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable.

  20. Optical heat flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

    1989-06-07

    A heat flux gauge comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figs.

  1. Optical heat flux gauge

    SciTech Connect

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MaCarthur, C.D.; Cala, G.C.

    1991-09-03

    A heat flux gauge is described comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.

  2. Rod examination gauge

    SciTech Connect

    Bacvinskas, W.S.; Bayer, J.E.; Davis, W.W.; Fodor, G.; Kikta, T.J.; Matchett, R.L.; Nilsen, R.J.; Wilczynski, R.

    1991-12-31

    The present invention is directed to a semi-automatic rod examination gauge for performing a large number of exacting measurements on radioactive fuel rods. The rod examination gauge performs various measurements underwater with remote controlled machinery of high reliability. The rod examination gauge includes instruments and a closed circuit television camera for measuring fuel rod length, free hanging bow measurement, diameter measurement, oxide thickness measurement, cladding defect examination, rod ovality measurement, wear mark depth and volume measurement, as well as visual examination. A control system is provided including a programmable logic controller and a computer for providing a programmed sequence of operations for the rod examination and collection of data.

  3. Supersymmetric QCD on the lattice: An exploratory study

    NASA Astrophysics Data System (ADS)

    Costa, M.; Panagopoulos, H.

    2017-08-01

    We perform a pilot study of the perturbative renormalization of a supersymmetric gauge theory with matter fields on the lattice. As a specific example, we consider supersymmetric N =1 QCD (SQCD). We study the self-energies of all particles which appear in this theory, as well as the renormalization of the coupling constant. To this end we compute, perturbatively to one-loop, the relevant two-point and three-point Green's functions using both dimensional and lattice regularizations. Our lattice formulation involves the Wilson discretization for the gluino and quark fields; for gluons we employ the Wilson gauge action; for scalar fields (squarks) we use naïve discretization. The gauge group that we consider is S U (Nc), while the number of colors, Nc, the number of flavors, Nf, and the gauge parameter, α , are left unspecified. We obtain analytic expressions for the renormalization factors of the coupling constant (Zg) and of the quark (Zψ), gluon (Zu), gluino (Zλ), squark (ZA ±), and ghost (Zc) fields on the lattice. We also compute the critical values of the gluino, quark and squark masses. Finally, we address the mixing which occurs among squark degrees of freedom beyond tree level: we calculate the corresponding mixing matrix which is necessary in order to disentangle the components of the squark field via an additional finite renormalization.

  4. {rho} meson decay in 2+1 flavor lattice QCD

    SciTech Connect

    Aoki, S.; Ishizuka, N.; Taniguchi, Y.; Ukawa, A.; Yoshie, T.; Ishikawa, K-I.; Okawa, M.; Kanaya, K.; Kuramashi, Y.; Namekawa, Y.; Ukita, N.; Yamazaki, T.

    2011-11-01

    We perform a lattice QCD study of the {rho} meson decay from the N{sub f}=2+1 full QCD configurations generated with a renormalization group improved gauge action and a nonperturbatively O(a)-improved Wilson fermion action. The resonance parameters, the effective {rho}{yields}{pi}{pi} coupling constant and the resonance mass, are estimated from the P-wave scattering phase shift for the isospin I=1 two-pion system. The finite size formulas are employed to calculate the phase shift from the energy on the lattice. Our calculations are carried out at two quark masses, m{sub {pi}=}410 MeV (m{sub {pi}/}m{sub {rho}=}0.46) and m{sub {pi}=}300 MeV (m{sub {pi}/}m{sub {rho}=}0.35), on a 32{sup 3}x64 (La=2.9 fm) lattice at the lattice spacing a=0.091 fm. We compare our results at these two quark masses with those given in the previous works using N{sub f}=2 full QCD configurations and the experiment.

  5. All Tree-level Amplitudes in Massless QCD

    SciTech Connect

    Dixon, Lance J.; Henn, Johannes M.; Plefka, Jan; Schuster, Theodor; /Humboldt U., Berlin

    2010-10-25

    We derive compact analytical formulae for all tree-level color-ordered gauge theory amplitudes involving any number of external gluons and up to three massless quark-anti-quark pairs. A general formula is presented based on the combinatorics of paths along a rooted tree and associated determinants. Explicit expressions are displayed for the next-to-maximally helicity violating (NMHV) and next-to-next-to-maximally helicity violating (NNMHV) gauge theory amplitudes. Our results are obtained by projecting the previously-found expressions for the super-amplitudes of the maximally supersymmetric Yang-Mills theory (N = 4 SYM) onto the relevant components yielding all gluon-gluino tree amplitudes in N = 4 SYM. We show how these results carry over to the corresponding QCD amplitudes, including massless quarks of different flavors as well as a single electroweak vector boson. The public Mathematica package GGT is described, which encodes the results of this work and yields analytical formulae for all N = 4 SYM gluon-gluino trees. These in turn yield all QCD trees with up to four external arbitrary-flavored massless quark-anti-quark-pairs.

  6. Canonical quantization theory of general singular QED system of Fermi field interaction with generally decomposed gauge potential

    SciTech Connect

    Zhang, Zhen-Lu; Huang, Yong-Chang

    2014-03-15

    Quantization theory gives rise to transverse phonons for the traditional Coulomb gauge condition and to scalar and longitudinal photons for the Lorentz gauge condition. We describe a new approach to quantize the general singular QED system by decomposing a general gauge potential into two orthogonal components in general field theory, which preserves scalar and longitudinal photons. Using these two orthogonal components, we obtain an expansion of the gauge-invariant Lagrangian density, from which we deduce the two orthogonal canonical momenta conjugate to the two components of the gauge potential. We then obtain the canonical Hamiltonian in the phase space and deduce the inherent constraints. In terms of the naturally deduced gauge condition, the quantization results are exactly consistent with those in the traditional Coulomb gauge condition and superior to those in the Lorentz gauge condition. Moreover, we find that all the nonvanishing quantum commutators are permanently gauge-invariant. A system can only be measured in physical experiments when it is gauge-invariant. The vanishing longitudinal vector potential means that the gauge invariance of the general QED system cannot be retained. This is similar to the nucleon spin crisis dilemma, which is an example of a physical quantity that cannot be exactly measured experimentally. However, the theory here solves this dilemma by keeping the gauge invariance of the general QED system. -- Highlights: •We decompose the general gauge potential into two orthogonal parts according to general field theory. •We identify a new approach for quantizing the general singular QED system. •The results obtained are superior to those for the Lorentz gauge condition. •The theory presented solves dilemmas such as the nucleon spin crisis.

  7. The Dynamics and Thermodynamics of Soft-Wall AdS/QCD

    NASA Astrophysics Data System (ADS)

    Kelley, Thomas Matthew

    Gauge/Gravity dualities open the non-perturbative realms of strongly-coupled gauge theories to analytic treatment. Anti-de Sitter Space/Conformal Field Theory, one way of connecting gravity dual models to gauge theories, is a correspondence between a ten-dimensional Type IIB superstring theory in AdS5 x S5 and a N=4 super Yang Mills theory. To describe systems that are experimentally accessible, however, the formal correspondence is modified into a phenomenological duality between a five-dimensional gravity model and a strongly coupled QCD-like gauge theory. This duality is referred to as AdS/QCD. This work explores aspects of the soft-wall AdS/QCD model. The phrase 'soft wall' refers to the means of breaking the conformal symmetry and introducing a mass scale to the gauge side of the duality. We add higher-order terms to the soft-wall Lagrangian and calculate the effect on physical observables. Meson mass spectra gain a more complex structure, exhibiting a better match with the experimental values than previous models. The Gell-Mann--Oakes--Renner relation naturally emerges from the model. We calculate the form factor Fpi and the coupling grhopipi as a non-trivial test on the limits of our soft-wall model. Introducing a black brane into the gravity dual metric allows us to derive thermodynamic quantities in the gauge theory. As expected at high temperatures, the entropy scales as the cube of the temperature, and the speed of sound reaches its conformal limit of one-third. Thermal condensates contribute leading-order terms, modifying the temperature, entropy, and free energy behavior. We find that the system undergoes a phase transition from hadronic matter to a strongly coupled quark-gluon plasma at a critical temperature.

  8. Spectrum and mass anomalous dimension of SU(2) adjoint QCD with two Dirac flavors

    NASA Astrophysics Data System (ADS)

    Bergner, Georg; Giudice, Pietro; Münster, Gernot; Montvay, Istvan; Piemonte, Stefano

    2017-08-01

    In this work we present the results of our investigation of SU(2) gauge theory with two Dirac fermions in the adjoint representation (aQCD2), which belongs to the class of strongly interacting gauge theories that are of basic interest for extensions of the Standard Model. We have done numerical lattice simulations of this theory at two different values of the gauge coupling and several fermion masses. Our results include the particle spectrum and the mass anomalous dimension. The spectrum contains new exotic fermion-gluon states and flavor-singlet mesons. The mass anomalous dimension is determined from the scaling of the masses and the mode number. The remnant dependence of the universal mass ratios and mass anomalous dimension on the gauge coupling indicates the relevance of scaling corrections, such that earlier estimations for the universal fixed point value of the mass anomalous dimension are incomplete without their inclusion.

  9. QCD measurements at the Tevatron

    SciTech Connect

    Bandurin, Dmitry; /Florida State U.

    2011-12-01

    Selected quantum chromodynamics (QCD) measurements performed at the Fermilab Run II Tevatron p{bar p} collider running at {radical}s = 1.96 TeV by CDF and D0 Collaborations are presented. The inclusive jet, dijet production and three-jet cross section measurements are used to test perturbative QCD calculations, constrain parton distribution function (PDF) determinations, and extract a precise value of the strong coupling constant, {alpha}{sub s}(m{sub Z}) = 0.1161{sub -0.0048}{sup +0.0041}. Inclusive photon production cross-section measurements reveal an inability of next-to-leading-order (NLO) perturbative QCD (pQCD) calculations to describe low-energy photons arising directly in the hard scatter. The diphoton production cross-sections check the validity of the NLO pQCD predictions, soft-gluon resummation methods implemented in theoretical calculations, and contributions from the parton-to-photon fragmentation diagrams. Events with W/Z+jets productions are used to measure many kinematic distributions allowing extensive tests and tunes of predictions from pQCD NLO and Monte-Carlo (MC) event generators. The charged-particle transverse momenta (p{sub T}) and multiplicity distributions in the inclusive minimum bias events are used to tune non-perturbative QCD models, including those describing the multiple parton interactions (MPI). Events with inclusive production of {gamma} and 2 or 3 jets are used to study increasingly important MPI phenomenon at high p{sub T}, measure an effective interaction cross section, {sigma}{sub eff} = 16.4 {+-} 2.3 mb, and limit existing MPI models.

  10. Canonical quantization of four- and five-dimensional U(1) gauge theories

    NASA Astrophysics Data System (ADS)

    Shnerb, N.; Horwitz, L. P.

    1993-12-01

    We discuss the canonical quantization of an interacting massless U(1) gauge field using a bosonic gauge-fixing method. We present a way to make the transformation between the Lorentz and the Coulomb gauge of such theories, without using an explicit representation of the fields in terms of creation-annihilation operators. We demonstrate this method in the case of Maxwell photons interacting with Schrödinger electrons and then we treat, with the same methods, a system of higher-dimensional equations appearing in the framework of a manifestly covariant relativistic quantum theory. The nonrelativistic limit of the Coulomb term for such a theory is discussed and compared to the Fokker action appearing in the Wheeler-Feynman action-at-a-distance theory for electromagnetic interactions.

  11. Natural Poincare gauge model

    SciTech Connect

    Aldrovandi, R.; Pereira, J.G.

    1986-05-15

    Because it acts on space-time and is not semisimple, the Poincare group cannot lead to a gauge theory of the usual kind. A candidate model is discussed which keeps itself as close as possible to the typical gauge scheme. Its field equations are the Yang-Mills equations for the Poincare group. It is shown that there exists no Lagrangian for these equations.

  12. Chiral limit of QCD

    SciTech Connect

    Gupta, R.

    1994-12-31

    This talk contains an analysis of quenched chiral perturbation theory and its consequences. The chiral behavior of a number of quantities such as the pion mass m{sub pi}{sup 2}, the Bernard-Golterman ratios R and {sub X}, the masses of nucleons, and the kaon B-parameter are examined to see if the singular terms induced by the additional Goldstone boson, {eta}{prime}, are visible in present data. The overall conclusion (different from that presented at the lattice meeting) of this analysis is that even though there are some caveats attached to the indications of the extra terms induced by {eta}{prime} loops, the standard expressions break down when extrapolating the quenched data with m{sub q} < m{sub s}/2 to physical light quarks. I then show that due to the single and double poles in the quenched {eta}{prime}, the axial charge of the proton cannot be calculated using the Adler-Bell-Jackiw anomaly condition. I conclude with a review of the status of the calculation of light quark masses from lattice QCD.

  13. QCD at collider energies

    NASA Astrophysics Data System (ADS)

    Nicolaidis, A.; Bordes, G.

    1986-05-01

    We examine available experimental distributions of transverse energy and transverse momentum, obtained at the CERN pp¯ collider, in the context of quantum chromodynamics. We consider the following. (i) The hadronic transverse energy released during W+/- production. This hadronic transverse energy is made out of two components: a soft component which we parametrize using minimum-bias events and a semihard component which we calculate from QCD. (ii) The transverse momentum of the produced W+/-. If the transverse momentum (or the transverse energy) results from a single gluon jet we use the formalism of Dokshitzer, Dyakonov, and Troyan, while if it results from multiple-gluon emission we use the formalism of Parisi and Petronzio. (iii) The relative transverse momentum of jets. While for W+/- production quarks play an essential role, jet production at moderate pT and present energies is dominated by gluon-gluon scattering and therefore we can study the Sudakov form factor of the gluon. We suggest also how through a Hankel transform of experimental data we can have direct access to the Sudakov form factors of quarks and gluons.

  14. Hadroquarkonium from lattice QCD

    NASA Astrophysics Data System (ADS)

    Alberti, Maurizio; Bali, Gunnar S.; Collins, Sara; Knechtli, Francesco; Moir, Graham; Söldner, Wolfgang

    2017-04-01

    The hadroquarkonium picture [S. Dubynskiy and M. B. Voloshin, Phys. Lett. B 666, 344 (2008), 10.1016/j.physletb.2008.07.086] provides one possible interpretation for the pentaquark candidates with hidden charm, recently reported by the LHCb Collaboration, as well as for some of the charmoniumlike "X , Y , Z " states. In this picture, a heavy quarkonium core resides within a light hadron giving rise to four- or five-quark/antiquark bound states. We test this scenario in the heavy quark limit by investigating the modification of the potential between a static quark-antiquark pair induced by the presence of a hadron. Our lattice QCD simulations are performed on a Coordinated Lattice Simulations (CLS) ensemble with Nf=2 +1 flavors of nonperturbatively improved Wilson quarks at a pion mass of about 223 MeV and a lattice spacing of about a =0.0854 fm . We study the static potential in the presence of a variety of light mesons as well as of octet and decuplet baryons. In all these cases, the resulting configurations are favored energetically. The associated binding energies between the quarkonium in the heavy quark limit and the light hadron are found to be smaller than a few MeV, similar in strength to deuterium binding. It needs to be seen if the small attraction survives in the infinite volume limit and supports bound states or resonances.

  15. Color Confinement and Screening in the θ Vacuum of QCD

    DOE PAGES

    Kharzeev, Dmitri E.; Levin, Eugene M.

    2015-06-16

    QCD perturbation theory ignores the compact nature of the SU(3) gauge group that gives rise to the periodic θ vacuum of the theory. In this paper, we propose to modify the gluon propagator to reconcile perturbation theory with the anomalous Ward identities for the topological current in the θ vacuum. As a result, the gluon couples to the Veneziano ghost describing the tunneling transitions between different Chern-Simons sectors of the vacuum; we call the emerging gluon dressed by ghost loops a “glost.” We evaluate the glost propagator and find that it has the form G(p)=(p2+χtop/p2)-1 where χtop is the Yang-Millsmore » topological susceptibility related to the η" mass by the Witten-Veneziano relation; this propagator describes the confinement of gluons at distances ~χtop-1/4≃1 fm. The same functional form of the propagator was originally proposed by Gribov as a solution to the gauge copies problem that plagues perturbation theory. The resulting running coupling coincides with the perturbative one at p2>>√χtop, but in the infrared region either freezes (in pure Yang-Mills theory) or vanishes (in full QCD with light quarks), in accord with experimental evidence. In conclusion, our scenario makes explicit the connection between confinement and topology of the QCD vacuum; we discuss the implications for spin physics, high energy scattering, and the physics of quark-gluon plasma.« less

  16. Perturbative aspects of the phase diagram of QCD with heavy quarks

    NASA Astrophysics Data System (ADS)

    Serreau, Julien; Reinosa, Urko

    2017-03-01

    We report on recent progress in the description of the phase diagram of QCD with heavy quarks at nonzero temperature and chemical potential in the context of a modified perturbative approach. The latter is based on a simple massive extension of the QCD Lagrangian in the Landau-DeWitt gauge, the background field generalization of the Landau gauge. Here, the background field plays the role of an order parameter for the center symmetry, relevant for confinement-deconfinement transition. One-loop results in this approach give a fairly accurate description of the phase diagram both at real and imaginary chemical potential. We comment on issues related to the sign problem in continuum approaches. Based on works in collaboration with Matthieu Tissier and Nicolás Wschebor.

  17. LHC signals for warped electroweak charged gauge bosons

    SciTech Connect

    Agashe, Kaustubh; Gopalakrishna, Shrihari; Soni, Amarjit; Han Tao; Huang Guiyu

    2009-10-01

    We study signals at the LHC for the Kaluza-Klein (KK) excitations of electroweak charged gauge bosons in the framework of the standard model (SM) fields propagating in the bulk of a warped extra dimension. Such a scenario can solve both the Planck-weak and flavor hierarchy problems of the SM. There are two such charged states in this scenario with couplings to light quarks and leptons being suppressed relative to those in the SM, whereas the couplings to top/bottom quarks are enhanced, similar to the case of electroweak neutral gauge bosons previously studied. However, unlike the case of electroweak neutral gauge bosons, there is no irreducible QCD background (including pollution from possibly degenerate KK gluons) for decays to top+bottom final states so that this channel is useful for the discovery of the charged states. Moreover, decays of electroweak charged gauge bosons to longitudinal W, Z and Higgs are enhanced just as for the neutral bosons. However, unlike for the neutral gauge bosons, the purely leptonic (and hence clean) decay mode of the WZ is fully reconstructible so that the ratio of the signal to the SM (electroweak) background can potentially be enhanced by restricting to the resonance region more efficiently. We show that such final states can give sensitivity to 2(3) TeV masses with an integrated luminosity of 100(300) fb{sup -1}. We emphasize that improvements in discriminating a QCD jet from a highly boosted hadronically decaying W, and a highly boosted top jet from a bottom jet will enhance the reach for these KK particles, and that the signals we study for the warped extra dimensional model might actually be applicable also to a wider class of nonsupersymmetric models of electroweak symmetry breaking.

  18. RIKEN WINTER SCHOOL: STRUCTURE OF HADRONS - INTRODUCTION TO QCD HARD PROCESSES. PROCEEDINGS OF RIKEN BNL RESEARCH CENTER WORKSHOP, DECEMBER 9-12, 1998.

    SciTech Connect

    SAITO,N.

    1999-12-09

    In this lecture I give a pedagogical introduction to the Perturbative QCD to understand the short-distance dynamics of the strong interaction. Starting with fundamental concepts such as the color degree of freedom of QCD, non-abelian gauge field theory, renormalization group equation etc., I explain a basic idea of the perturbative QCD and apply this idea to the e{sup +}e{sup {minus}} processes and the structure functions. The notion of mass singularity and the necessity of its factorization is discussed in some detail.

  19. Microcanonical determination of effective-spin models for finite-temperature QCD

    NASA Astrophysics Data System (ADS)

    Gocksch, A.; Ogilvie, M.

    1985-04-01

    The microcanonical-reorganization-group techniques developed by Creutz, et al. (1984) are applied to computer-simulation effective-spin models for finite-temperature QCD in SU(3) gauge theory. The effective-spin-model coupling coefficient J is plotted against the gauge-field coupling coefficient lambda; the results are compared with the predictions of strong-coupling (Green and Karsch, 1984) and weak-coupling (Kadanoff, 1977) theory; and the implications of the transition to a new phase of deconfined quarks and gluons for cosmology are indicated.

  20. Recent QCD results from the Tevatron

    SciTech Connect

    Pickarz, Henryk; CDF and DO collaboration

    1997-02-01

    Recent QCD results from the CDF and D0 detectors at the Tevatron proton-antiproton collider are presented. An outlook for future QCD tests at the Tevatron collider is also breifly discussed. 27 refs., 11 figs.

  1. Bethe ansatz for QCD pomeron

    NASA Astrophysics Data System (ADS)

    Korchemsky, G. P.

    1995-02-01

    The equivalence is found between high-energy QCD in the generalized leading logarithmic approximation and the one-dimensional Heisenberg magnet. According to Regge theory, the high-energy asymptotics of hadronic scattering amplitudes are related to singularities of partial waves in the complex angular momentum plane. In QCD, the partial waves are determined by nontrivial two-dimensional dynamics of the transverse gluonic degrees of freedom. The "bare" gluons interact with each other to form a collective excitation, the Reggeon. The partial waves of the scattering amplitude satisfy the Bethe-Salpeter equation whose solutions describe the color singlet compound states of Reggeons - Pomeron, Odderon and higher Reggeon states. We show that the QCD Hamiltonian for reggeized gluons coincides in the multi-color limit with the Hamiltonian of XXX Heisenberg magnet for spin s = 0 and spin operators being the generators of the conformal SL(2,C) group. As a result, the Schrödinger equation for the compound states of Reggeons has a sufficient number of conservation laws to be completely integrable. A generalized Bethe ansatz is developed for the diagonalization of the QCD Hamiltonian and for the calculation of hadron-hadron scattering. Using the Bethe Ansatz solution of high-energy QCD we investigate the properties of the Reggeon compound states which govern the Regge behavior of the total hadron-hadron cross sections and the small-x behavior of the structure functions deep inelastic scattering.

  2. Coulomb explosion of “hot spot”

    SciTech Connect

    Oreshkin, V. I.; Oreshkin, E. V.; Chaikovsky, S. A.; Artyomov, A. P.

    2016-09-15

    The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed, and the estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

  3. Coulomb wave functions in momentum space

    SciTech Connect

    Eremenko, V.; Upadhyay, N. J.; Thompson, I. J.; Elster, Ch.; Nunes, F. M.; Arbanas, G.; Escher, J. E.; Hlophe, L.

    2015-10-15

    We present an algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space. The arguments are the Sommerfeld parameter η, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p → q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of vertical bar eta vertical bar in the range of 10-1 to 10, and thus is particularly suited for momentum space calculations of nuclear reactions.

  4. Coulomb wave functions in momentum space

    DOE PAGES

    Eremenko, V.; Upadhyay, N. J.; Thompson, I. J.; ...

    2015-10-15

    We present an algorithm to calculate non-relativistic partial-wave Coulomb functions in momentum space. The arguments are the Sommerfeld parameter η, the angular momentum l, the asymptotic momentum q and the 'running' momentum p, where both momenta are real. Since the partial-wave Coulomb functions exhibit singular behavior when p → q, different representations of the Legendre functions of the 2nd kind need to be implemented in computing the functions for the values of p close to the singularity and far away from it. The code for the momentum-space Coulomb wave functions is applicable for values of vertical bar eta vertical barmore » in the range of 10-1 to 10, and thus is particularly suited for momentum space calculations of nuclear reactions.« less

  5. Counterintuitive Coulomb hole around the bond midplane.

    PubMed

    Wang, Jian; Kim, Kwang S; Baerends, Evert Jan

    2010-05-28

    The Coulomb hole does not have its largest depth around an electron in or near the bond midplane. It splits into two parts, localized on both nuclear sites forming the bond. Even counterintuitive positive values of the "hole" around such a position may be observed. This happens when the Fermi hole is deeper than the total exchange-correlation hole at the reference electron position. This Coulomb "heap" is shown to arise from correlation effects on the one-electron density rather than correlation effects in the pair density. Left-right correlation tends to enhance the effect of the nuclear attraction, contracting the electron density around the nuclear positions and depleting the bond center region. Possible alternative definitions of the Coulomb hole are discussed, including one based on the exact Kohn-Sham exchange hole. Approximate density functional theory methods (generalized gradient approximation) are not accurate enough to realize the advantages of this definition.

  6. Coulomb bound states of strongly interacting photons

    SciTech Connect

    Maghrebi, M. F.; Choi, S.; Martin, I.; Firstenberg, O.; Lukin, M. D.; Büchler, H. P.; Gorshkov, A. V.

    2015-09-16

    We show that two photons coupled to Rydberg states via electromagnetically induced transparency (EIT) can interact via an effective Coulomb potential. The interaction then gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb problem, thus obtaining a photonic analogue of the hydrogen atom. These states propagate with a negative group velocity in the medium, which allows for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms. As a result, we verify the metastability and backward propagation of these Coulomb bound states with exact numerical simulations.

  7. Coulomb bound states of strongly interacting photons

    DOE PAGES

    Maghrebi, M. F.; Gullans, Michael J.; Bienias, P.; ...

    2015-09-16

    We show that two photons coupled to Rydberg states via electromagnetically induced transparency (EIT) can interact via an effective Coulomb potential. The interaction then gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasi-bound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb problem, thus obtaining a photonic analogue of the hydrogen atom. These states propagate with a negative group velocity in the medium, which allows for a simple preparation and detection scheme, before they slowlymore » decay to pairs of bound Rydberg atoms. As a result, we verify the metastability and backward propagation of these Coulomb bound states with exact numerical simulations.« less

  8. A ghost story (II): Ghost, Gluons and the Gluon Condensate beyond the IR of QCD

    NASA Astrophysics Data System (ADS)

    Rodriguez-Quintero, J.; Pene, O.; Boucaud, P.; Micheli, J.; Le Yaouanc, A.; Leroy, J. P.; de Soto, F.

    Beyond the deep IR, the analysis of ghost and gluon propagators still keeps very interesting non-perturbative information. The Taylor-scheme coupling can be computed and applied to obtain the $\\Lambda_{\\rm QCD}$ parameter from Landau gauge lattice simulations. Furthermore, a dimension-two gluon condensate, that can be understood in the instanton liquid model, plays an important role in the game.

  9. QCD diffraction: a critical phenomenon reflecting both confinement and chiral-symmetry breaking

    SciTech Connect

    White, A.R.

    1982-07-01

    Arguments are presented for studying soft diffractive physics at anti p-p colliders in terms of Critical Pomeron Reggeon Field Theory. It is emphasized that both confinement and chiral-symmetry breaking play a vital role in the occurrence of the Critical Pomeron in QCD. SU(3) is the unique strong-interaction gauge group giving the Critical Pomeron and the maximum number of quarks allowed by asymptotic freedom is required for criticality.

  10. Spectrum of the QCD Dirac operator and chiral random matrix theory

    SciTech Connect

    Verbaarschot, J. )

    1994-04-18

    We argue that the spectrum of the QCD Dirac operator near zero virtuality can be described by random matrix theory. As in the case of the classical random matrix ensembles of Dyson we have three different cases: the chiral orthogonal ensemble, the chiral unitary ensemble, and the chiral symplectic ensemble. They correspond to gauge groups SU(2) in the fundamental representation, SU([ital N][sub [ital c

  11. Doubly heavy baryons in a Salpeter model with AdS/QCD inspired potential

    SciTech Connect

    Giannuzzi, Floriana

    2009-05-01

    The spectrum of baryons with two heavy quarks is predicted, assuming a configuration of a light quark and a heavy diquark. The masses are computed within a semirelativistic quark model, using a potential obtained in a gauge-gravity (anti-de Sitter/QCD) framework. All the parameters defining the model are determined fitting the meson spectrum. The obtained mass of {xi}{sub cc} is in agreement with the measurements.

  12. Non-Abelian strings in N =1 supersymmetric QCD

    NASA Astrophysics Data System (ADS)

    Ievlev, E.; Yung, A.

    2017-06-01

    Non-Abelian flux tubes (strings) are well studied in N =2 supersymmetric QCD in (3 +1 ) dimensions. In addition to translational zero modes they have also orientational moduli associated with rotations of their fluxes inside a non-Abelian group. The dynamics of the orientational moduli is described by the two-dimensional C P (N -1 ) model living on the world sheet of the non-Abelian string. In this paper we consider a deformation of N =2 supersymmetric QCD with the U (N ) gauge group and Nf=N quark flavors with a mass term μ of the adjoint matter. In the limit of large μ the theory flows to an N =1 supersymmetric QCD. We study the solution for the non-Abelian string in this limit and derive an effective theory on the string world sheet. The bosonic sector of this theory is still given by the C P (N -1 ) model but its scale is exponentially small as compared to the scale of the four-dimensional bulk theory in contrast to the N =2 case where these scales are equal. We study also the fermionic sector of the world sheet theory. Upon the deformation, the non-Abelian string is no longer Bogomol'nyi-Prasad-Sommerfield (BPS) state and we show that the fermionic superorientational zero modes are all lifted. This leaves us with the pure bosonic C P (N -1 ) model on the string world sheet in the limit of N =1 QCD. We also discuss what happens to confined monopoles at large μ .

  13. Twisted mass QCD for weak matrix elements

    NASA Astrophysics Data System (ADS)

    Pena, Carlos

    2006-12-01

    I report on the application of tmQCD techniques to the computation of hadronic matrix elements of four-fermion operators. Emphasis is put on the computation of BK in quenched QCD performed by the ALPHA Collaboration. The extension of tmQCD strategies to the study of neutral B- meson mixing is briefly discussed. Finally, some remarks are made concerning proposals to apply tmQCD to the computation of K → ππ amplitudes.

  14. Three-body Coulomb continuum problem

    NASA Astrophysics Data System (ADS)

    Berakdar, J.; Briggs, J. S.

    1994-06-01

    A symmetric representation of the three-body Coulomb continuum wave function as a product of three two-body Coulomb wave functions is modified to allow for three-body effects whereby the Sommerfeld parameter describing the strength of interaction of any two particles is affected by the presence of the third particle. This approach gives excellent agreement with near-threshold absolute (e,2e) ionization cross sections. In particular a recently observed deep minimum in noncoplanar geometry is reproduced for the first time.

  15. Observation of ionic Coulomb blockade in nanopores

    NASA Astrophysics Data System (ADS)

    Feng, Jiandong; Liu, Ke; Graf, Michael; Dumcenco, Dumitru; Kis, Andras; di Ventra, Massimiliano; Radenovic, Aleksandra

    2016-08-01

    Emergent behaviour from electron-transport properties is routinely observed in systems with dimensions approaching the nanoscale. However, analogous mesoscopic behaviour resulting from ionic transport has so far not been observed, most probably because of bottlenecks in the controlled fabrication of subnanometre nanopores for use in nanofluidics. Here, we report measurements of ionic transport through a single subnanometre pore junction, and the observation of ionic Coulomb blockade: the ionic counterpart of the electronic Coulomb blockade observed for quantum dots. Our findings demonstrate that nanoscopic, atomically thin pores allow for the exploration of phenomena in ionic transport, and suggest that nanopores may also further our understanding of transport through biological ion channels.

  16. Nonlocal Coulomb drag in Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Baum, Yuval; Stern, Ady

    2017-02-01

    Nonlocality is one of the most striking signatures of the topological nature of Weyl semimetals. We propose to probe the nonlocality in these materials via a measurement of a magnetic-field-dependent Coulomb drag between two sheets of graphene which are separated by a three-dimensional slab of Weyl semimetal. We predict a mechanism of Coulomb drag, based on cyclotron orbits that are split between opposite surfaces of the semimetal. In the absence of impurity scattering between different Weyl nodes, this mechanism does not decay with the thickness of the semimetal.

  17. Transverse structure of the QCD string

    SciTech Connect

    Meyer, Harvey B.

    2010-11-15

    The characterization of the transverse structure of the QCD string is discussed. We formulate a conjecture as to how the stress-energy tensor of the underlying gauge theory couples to the string degrees of freedom. A consequence of the conjecture is that the energy density and the longitudinal-stress operators measure the distribution of the transverse position of the string, to leading order in the string fluctuations, whereas the transverse-stress operator does not. We interpret recent numerical measurements of the transverse size of the confining string and show that the difference of the energy and longitudinal-stress operators is a particularly natural probe at next-to-leading order. Second, we derive the constraints imposed by open-closed string duality on the transverse structure of the string. We show that a total of three independent ''gravitational'' form factors characterize the transverse profile of the closed string, and obtain the interpretation of recent effective string theory calculations: the square radius of a closed string of length {beta} defined from the slope of its gravitational form factor, is given by (d-1/2{pi}{sigma})log({beta}/4r{sub 0}) in d space dimensions. This is to be compared with the well-known result that the width of the open string at midpoint grows as (d-1/2{pi}{sigma})log(r/r{sub 0}). We also obtain predictions for transition form factors among closed-string states.

  18. Heavy-Baryon Spectroscopy from Lattice QCD

    SciTech Connect

    Huey-Wen Lin, Saul D. Cohen, Liuming Liu, Nilmani Mathur, Konstantinos Orginos, Andre Walker-Loud

    2011-01-01

    We use a four-dimensional lattice calculation of the full-QCD (quantum chromodynamics, the non-abliean gauge theory of the strong interactions of quarks and gluons) path integrals needed to determine the masses of the charmed and bottom baryons. In the charm sector, our results are in good agreement with experiment within our systematics, except for the spin-1/2 $\\Xi_{cc}$, for which we found the isospin-averaged mass to be $\\Xi_{cc}$ to be $3665\\pm17\\pm14^{+0}_{-78}$ MeV. We predict the mass of the (isospin-averaged) spin-1/2 $\\Omega_{cc}$ to be $3763\\pm19\\pm26^{+13}_{-79}$ {MeV}. In the bottom sector, our results are also in agreement with experimental observations and other lattice calculations within our statistical and systematic errors. In particular, we find the mass of the $\\Omega_b$ to be consistent with the recent CDF measurement. We also predict the mass for the as yet unobserved $\\Xi^\\prime_b$ to be 5955(27) MeV.

  19. Nonperturbative comparison of QCD effective charges

    SciTech Connect

    Aguilar, A. C.; Binosi, D.; Papavassiliou, J.; Rodriguez-Quintero, J.

    2009-10-15

    We study the nonperturbative behavior of two versions of the QCD effective charge, one obtained from the pinch technique gluon self-energy, and one from the ghost-gluon vertex. Despite their distinct theoretical origin, due to a fundamental identity relating various ingredients appearing in their respective definitions, the two effective charges are almost identical in the entire range of physical momenta, and coincide exactly in the deep infrared, where they freeze at a common finite value. Specifically, the dressing function of the ghost propagator is related to the two form factors in the Lorentz decomposition of a certain Green's function, appearing in a variety of field-theoretic contexts. The central identity, which is valid only in the Landau gauge, is derived from the Schwinger-Dyson equations governing the dynamics of the aforementioned quantities. The renormalization procedure that preserves the validity of the identity is carried out, and various relevant kinematic limits and physically motivated approximations are studied in detail. A crucial ingredient in this analysis is the infrared finiteness of the gluon propagator, which is inextricably connected with the aforementioned freezing of the effective charges. Some important issues related to the consistent definition of the effective charge in the presence of such a gluon propagator are resolved. We finally present a detailed numerical study of a special set of Schwinger-Dyson equations, whose solutions determine the nonperturbative dynamics of the quantities composing the two effective charges.

  20. LATTICE QCD THERMODYNAMICS WITH WILSON QUARKS.

    SciTech Connect

    EJIRI,S.

    2007-11-20

    We review studies of QCD thermodynamics by lattice QCD simulations with dynamical Wilson quarks. After explaining the basic properties of QCD with Wilson quarks at finite temperature including the phase structure and the scaling properties around the chiral phase transition, we discuss the critical temperature, the equation of state and heavy-quark free energies.

  1. Quantum chromodynamics (QCD) and collider physics

    SciTech Connect

    Ellis, R.K. ); Stirling, W.J. )

    1990-08-14

    This report discusses: fundamentals of perturbative QCD; QCD in e{sup +}e{sup {minus}} {yields} hadrons; deep inelastic scattering and parton distributions; the QCD parton model in hadron-hadron collisions; large p{sub T} jet production in hadron-hadron collisions; the production of vector bosons in hadronic collisions; and the production of heavy quarks.

  2. PDF uncertainties at large x and gauge boson production

    SciTech Connect

    Accardi, Alberto

    2012-10-01

    I discuss how global QCD fits of parton distribution functions can make the somewhat separated fields of high-energy particle physics and lower energy hadronic and nuclear physics interact to the benefit of both. In particular, I will argue that large rapidity gauge boson production at the Tevatron and the LHC has the highest short-term potential to constrain the theoretical nuclear corrections to DIS data on deuteron targets necessary for up/down flavor separation. This in turn can considerably reduce the PDF uncertainty on cross section calculations of heavy mass particles such as W' and Z' bosons.

  3. Scattering of composite particles in a gauge theory with confinement

    SciTech Connect

    Briere, J.F.; Kroger, H. )

    1989-08-21

    In order to model positronium-positronium scattering in QED or meson-meson scattering in QCD, we consider QED{sub 1+1}, which is a gauge theory and confines single fermions. We present first numerical results of a lattice calculation on scattering of two composite particles. The composite particles are taken as neutral, fermion-antifermion, lowest-mass eigenstates of the Hamiltonian. We use the light-cone momentum representation on a lattice and employ a nonperturbative time-dependent method to compute the {ital S} matrix.

  4. Lattice QCD Calculation of Nucleon Structure

    SciTech Connect

    Liu, Keh-Fei; Draper, Terrence

    2016-08-30

    It is emphasized in the 2015 NSAC Long Range Plan that "understanding the structure of hadrons in terms of QCD's quarks and gluons is one of the central goals of modern nuclear physics." Over the last three decades, lattice QCD has developed into a powerful tool for ab initio calculations of strong-interaction physics. Up until now, it is the only theoretical approach to solving QCD with controlled statistical and systematic errors. Since 1985, we have proposed and carried out first-principles calculations of nucleon structure and hadron spectroscopy using lattice QCD which entails both algorithmic development and large-scale computer simulation. We started out by calculating the nucleon form factors -- electromagnetic, axial-vector, πNN, and scalar form factors, the quark spin contribution to the proton spin, the strangeness magnetic moment, the quark orbital angular momentum, the quark momentum fraction, and the quark and glue decomposition of the proton momentum and angular momentum. The first round of calculations were done with Wilson fermions in the `quenched' approximation where the dynamical effects of the quarks in the sea are not taken into account in the Monte Carlo simulation to generate the background gauge configurations. Beginning in 2000, we have started implementing the overlap fermion formulation into the spectroscopy and structure calculations. This is mainly because the overlap fermion honors chiral symmetry as in the continuum. It is going to be more and more important to take the symmetry into account as the simulations move closer to the physical point where the u and d quark masses are as light as a few MeV only. We began with lattices which have quark masses in the sea corresponding to a pion mass at ~ 300 MeV and obtained the strange form factors, charm and strange quark masses, the charmonium spectrum and the Ds meson decay constant fDs, the strangeness and charmness, the meson mass decomposition and the

  5. A Coulomb-Like Off-Shell T-Matrix with the Correct Coulomb Phase Shift

    NASA Astrophysics Data System (ADS)

    Oryu, Shinsho; Watanabe, Takashi; Hiratsuka, Yasuhisa; Togawa, Yoshio

    2017-03-01

    We confirm the reliability of the well-known Coulomb renormalization method (CRM). It is found that the CRM is only available for a very-long-range screened Coulomb potential (SCP). However, such an SCP calculation in momentum space is considerably difficult because of the cancelation of significant digits. In contrast to the CRM, we propose a new method by using an on-shell equivalent SCP and the rest term. The two-potential theory with r-space is introduced, which defines fully the off-shell Coulomb amplitude.

  6. Archeology and evolution of QCD

    NASA Astrophysics Data System (ADS)

    De Rújula, A.

    2017-03-01

    These are excerpts from the closing talk at the "XIIth Conference on Quark Confinement and the Hadron Spectrum", which took place last Summer in Thessaloniki -an excellent place to enjoy an interest in archeology. A more complete personal view of the early days of QCD and the rest of the Standard Model is given in [1]. Here I discuss a few of the points which -to my judgement- illustrate well the QCD evolution (in time), both from a scientific and a sociological point of view.

  7. Lattice QCD: Status and Prospect

    SciTech Connect

    Ukawa, Akira

    2006-02-08

    A brief review is given of the current status and near-future prospect of lattice QCD studies of the Standard Model. After summarizing a bit of history, we describe current attempts toward inclusion of dynamical up, down and strange quarks. Recent results on the light hadron mass spectrum as well as those on the heavy quark quantities are described. Recent work on lattice pentaquark search is summarized. We touch upon the PACS-CS Project for building our next machine for lattice QCD, and conclude with a summary of computer situation and the physics possibilities over the next several years.

  8. Neutron star structure from QCD

    NASA Astrophysics Data System (ADS)

    Fraga, Eduardo S.; Kurkela, Aleksi; Vuorinen, Aleksi

    2016-03-01

    In this review article, we argue that our current understanding of the thermodynamic properties of cold QCD matter, originating from first principles calculations at high and low densities, can be used to efficiently constrain the macroscopic properties of neutron stars. In particular, we demonstrate that combining state-of-the-art results from Chiral Effective Theory and perturbative QCD with the current bounds on neutron star masses, the Equation of State of neutron star matter can be obtained to an accuracy better than 30% at all densities.

  9. Hadron scattering, resonances, and QCD

    SciTech Connect

    Briceno, Raul

    2016-12-01

    The non-perturbative nature of quantum chromodynamics (QCD) has historically left a gap in our understanding of the connection between the fundamental theory of the strong interactions and the rich structure of experimentally observed phenomena. For the simplest properties of stable hadrons, this is now circumvented with the use of lattice QCD (LQCD). In this talk I discuss a path towards a rigorous determination of few-hadron observables from LQCD. I illustrate the power of the methodology by presenting recently determined scattering amplitudes in the light-meson sector and their resonance content.

  10. The supercritical pomeron in QCD.

    SciTech Connect

    White, A. R.

    1998-06-29

    Deep-inelastic diffractive scaling violations have provided fundamental insight into the QCD pomeron, suggesting a single gluon inner structure rather than that of a perturbative two-gluon bound state. This talk outlines a derivation of a high-energy, transverse momentum cut-off, confining solution of QCD. The pomeron, in first approximation, is a single reggeized gluon plus a ''wee parton'' component that compensates for the color and particle properties of the gluon. This solution corresponds to a super-critical phase of Reggeon Field Theory.

  11. QCD inequalities for hadron interactions.

    PubMed

    Detmold, William

    2015-06-05

    We derive generalizations of the Weingarten-Witten QCD mass inequalities for particular multihadron systems. For systems of any number of identical pseudoscalar mesons of maximal isospin, these inequalities prove that near threshold interactions between the constituent mesons must be repulsive and that no bound states can form in these channels. Similar constraints in less symmetric systems are also extracted. These results are compatible with experimental results (where known) and recent lattice QCD calculations, and also lead to a more stringent bound on the nucleon mass than previously derived, m_{N}≥3/2m_{π}.

  12. Some Qcd/gravity Intersections

    NASA Astrophysics Data System (ADS)

    Teryaev, O. V.

    Gravitational form factors are the matrix elements of the Belinfante energy momentum tensor (EMT) which naturally incorporate the hadron structure and the equivalence principle. The relocalization property allowing to transform EMT to the Belinfante form provides the "kinematical" counterpart of the famous UA(1) problem. The equivalence principle may be approximately valid for quarks and gluons separately in non-perturbative (NP)QCD, and this conjecture is supported by the experimental and lattice data. The extradimensional gravity leading to holographic AdS/QCD is supporting the relation of quark transverse momentum to the Regge slope, discovered by V.N. Gribov.

  13. Some QCD/gravity intersections

    NASA Astrophysics Data System (ADS)

    Teryaev, O. V.

    2016-10-01

    Gravitational form factors are the matrix elements of the Belinfante energy momentum tensor (EMT) which naturally incorporate the hadron structure and the equivalence principle. The relocalization property allowing to transform EMT to the Belinfante form provides the “kinematical” counterpart of the famous UA(1) problem. The equivalence principle may be approximately valid for quarks and gluons separately in non-perturbative (NP)QCD, and this conjecture is supported by the experimental and lattice data. The extra-dimensional gravity leading to holographic AdS/QCD is supporting the relation of quark transverse momentum to the Regge slope, discovered by V.N. Gribov.

  14. Recent QCD results from CDF

    SciTech Connect

    Yun, J.C.

    1990-10-10

    In this paper we report recent QCD analysis with the new data taken from CDF detector. CDF recorded an integrated luminosity of 4.4 nb{sup {minus}1} during the 1988--1989 run at center of mass system (CMS) energy of 1.8 TeV. The major topics of this report are inclusive jet, dijet, trijet and direct photon analysis. These measurements are compared of QCD predictions. For the inclusive jet an dijet analysis, tests of quark compositeness are emphasized. 11 refs., 6 figs.

  15. Glueball decay in holographic QCD

    SciTech Connect

    Hashimoto, Koji; Tan, C.-I; Terashima, Seiji

    2008-04-15

    Using holographic QCD based on D4-branes and D8-anti-D8-branes, we have computed couplings of glueballs to light mesons. We describe glueball decay by explicitly calculating its decay widths and branching ratios. Interestingly, while glueballs remain less well understood both theoretically and experimentally, our results are found to be consistent with the experimental data for the scalar glueball candidate f{sub 0}(1500). More generally, holographic QCD predicts that decay of any glueball to 4{pi}{sup 0} is suppressed, and that mixing of the lightest glueball with qq mesons is small.

  16. Hadron masses and baryonic scales in G2-QCD at finite density

    NASA Astrophysics Data System (ADS)

    Wellegehausen, Björn H.; Maas, Axel; Wipf, Andreas; von Smekal, Lorenz

    2014-03-01

    The QCD phase diagram at densities relevant to neutron stars remains elusive, mainly due to the fermion-sign problem. At the same time, a plethora of possible phases has been predicted in models. Meanwhile G2-QCD, for which the SU(3) gauge group of QCD is replaced by the exceptional Lie group G2, does not have a sign problem and can be simulated at such densities using standard lattice techniques. It thus provides benchmarks to models and functional continuum methods, and it serves to unravel the nature of possible phases of strongly interacting matter at high densities. Instrumental in understanding these phases is that G2-QCD has fermionic baryons, and that it can therefore sustain a baryonic Fermi surface. Because the baryon spectrum of G2-QCD also contains bosonic diquark and probably other more exotic states, it is important to understand this spectrum before one can disentangle the corresponding contributions to the baryon density. Here we present a first systematic classification of this spectrum. The qualitative features of this spectrum are reflected in our simulation results at different quark masses although our lattices are still rather coarse. This allows us to relate the mass hierarchy, ranging from scalar would-be-Goldstone bosons and intermediate vector bosons to the G2 nucleons and deltas, to individual structures observed in the total baryon density at finite chemical potential.

  17. Two-color QCD at high density

    SciTech Connect

    Boz, Tamer; Skullerud, Jon-Ivar; Giudice, Pietro; Hands, Simon; Williams, Anthony G.

    2016-01-22

    QCD at high chemical potential has interesting properties such as deconfinement of quarks. Two-color QCD, which enables numerical simulations on the lattice, constitutes a laboratory to study QCD at high chemical potential. Among the interesting properties of two-color QCD at high density is the diquark condensation, for which we present recent results obtained on a finer lattice compared to previous studies. The quark propagator in two-color QCD at non-zero chemical potential is referred to as the Gor’kov propagator. We express the Gor’kov propagator in terms of form factors and present recent lattice simulation results.

  18. Effective Coulomb logarithm for one component plasma

    NASA Astrophysics Data System (ADS)

    Khrapak, Sergey A.

    2013-05-01

    An expression for the effective Coulomb logarithm in one-component-plasma is proposed, which allows to extend the applicability of the classical formula for the self-diffusion coefficient to the strongly coupled regime. The proposed analytical approximation demonstrates reasonable agreement with previous numerical simulation results. Relevance to weakly screened Yukawa systems (and, in particular, complex plasmas) is discussed.

  19. Bound states of screened coulomb potentials

    NASA Astrophysics Data System (ADS)

    Dutt, Ranabir; Ray, Aparna; Ray, Pritam P.

    1981-05-01

    We propose an extension of the Ecker-Weizel approximation to treat the non-zero angular momentum bound states of a class of screened Coulomb potentials. As an illustration of our prescription, we have calculated the discrete energies Enl of the Yukawa potential, which are in excellent agreement with those of Rogers et al.

  20. Electric-hexadecapole (24-pole) Coulomb integrals

    NASA Astrophysics Data System (ADS)

    Chidichimo, Marita C.; Stastna, Marek

    1996-03-01

    We obtain the quantal zero-energy-loss limit of the radial integrals arising in the nonrelativistic atomic excitation of electric-hexadecapole transitions. We compare these results to the classical limit and the WKB approximation. We show the different behavior of the Coulomb integrals in the WKB approximation in the cases of repulsive and attractive potentials as functions of the Sommerfeld number η.

  1. Coulomb drag between helical Luttinger liquids

    NASA Astrophysics Data System (ADS)

    Kainaris, N.; Gornyi, I. V.; Levchenko, A.; Polyakov, D. G.

    2017-01-01

    We theoretically study Coulomb drag between two helical edges with broken spin-rotational symmetry, such as would occur in two capacitively coupled quantum spin Hall insulators. For the helical edges, Coulomb drag is particularly interesting because it specifically probes the inelastic interactions that break the conductance quantization for a single edge. Using the kinetic equation formalism, supplemented by bosonization, we find that the drag resistivity ρD exhibits a nonmonotonic dependence on the temperature T . In the limit of low T ,ρD vanishes with decreasing T as a power law if intraedge interactions are not too strong. This is in stark contrast to Coulomb drag in conventional quantum wires, where ρD diverges at T →0 irrespective of the strength of repulsive interactions. Another unusual property of Coulomb drag between the helical edges concerns higher T for which, unlike in the Luttinger liquid model, drag is mediated by plasmons. The special type of plasmon-mediated drag can be viewed as a distinguishing feature of the helical liquid—because it requires peculiar umklapp scattering only available in the presence of a Dirac point in the electron spectrum.

  2. Solution of Coulomb system in momentum space

    SciTech Connect

    Lin, D.-H.

    2008-02-15

    The solution of D-dimensional Coulomb system is solved in momentum space by path integral. From which the topological effect of a magnetic flux in the system is given. It is revealed that the flux effect represented by the two-dimensional field of Aharonov-Bohm covers any space-dimensions.

  3. Molecular Dynamics Simulations of Coulomb Explosion

    SciTech Connect

    Bringa, E M

    2002-05-17

    A swift ion creates a track of electronic excitations in the target material. A net repulsion inside the track can cause a ''Coulomb Explosion'', which can lead to damage and sputtering of the material. Here we report results from molecular-dynamics (MD) simulations of Coulomb explosion for a cylindrical track as a function of charge density and neutralization/quenching time, {tau}. Screening by the free electrons is accounted for using a screened Coulomb potential for the interaction among charges. The yield exhibits a prompt component from the track core and a component, which dominates at higher excitation density, from the heated region produced. For the cases studied, the number of atoms ejected per incident ion, i.e. the sputtering yield Y, is quadratic with charge density along the track as suggested by simple models. Y({tau} = 0.2 Debye periods) is nearly 20% of the yield when there is no neutralization ({tau} {yields} {infinity}). The connections between ''Coulomb explosions'', thermal spikes and measurements of electronic sputtering are discussed.

  4. Effective Coulomb logarithm for one component plasma

    SciTech Connect

    Khrapak, Sergey A.

    2013-05-15

    An expression for the effective Coulomb logarithm in one-component-plasma is proposed, which allows to extend the applicability of the classical formula for the self-diffusion coefficient to the strongly coupled regime. The proposed analytical approximation demonstrates reasonable agreement with previous numerical simulation results. Relevance to weakly screened Yukawa systems (and, in particular, complex plasmas) is discussed.

  5. Coulomb's Electrical Measurements. Experiment No. 14.

    ERIC Educational Resources Information Center

    Devons, Samuel

    Presented is information related to the life and work of Charles Coulomb as well as detailed notes of his measurements of the distribution of electricity on conductors. The two methods that he used (the large torsion balance, and the timing of "force" oscillations) are described. (SA)

  6. The Pioneer Anomaly as a Coulomb Attraction

    NASA Astrophysics Data System (ADS)

    Morris, Steven

    2016-06-01

    The anomalous acceleration of the Pioneer 10 and Pioneer 11 spacecraft can be explained as a Coulomb attraction between the positively-charged Solar System (due to cosmic rays) and the negatively-charged spacecraft (due to alpha-particle emission from the radioisotope thermoelectric generators).

  7. Coulomb Logarithm, Version 1.0

    SciTech Connect

    Singleton, Robert

    2016-11-23

    Clog is a library of charged particle stopping powers and related Coulomb logarithm processes in a plasma. The stopping power is a particularly useful quantity for plasma physics, as it measures the energy loss of per unit length of charged particle as it traverses a plasma. Clog's primary stopping power is the BPS (Brown-Preston-Singleton) theory.

  8. Gravity, gauges and clocks

    NASA Astrophysics Data System (ADS)

    Teyssandier, Pierre; Tucker, Robin W.

    1996-01-01

    We discuss the definitions of standard clocks in theories of gravitation. These definitions are motivated by the invariance of actions under different gauge symmetries. We contrast the definition of a standard Weyl clock with that of a clock in general relativity and argue that the historical criticisms of theories based on non-metric compatible connections by Einstein, Pauli and others must be considered in the context of Weyl's original gauge symmetry. We argue that standard Einsteinian clocks can be defined in non-Riemannian theories of gravitation by adopting the Weyl group as a local gauge symmetry that preserves the metric and discuss the hypothesis that atomic clocks may be adopted to measure proper time in the presence of non-Riemannian gravitational fields. These ideas are illustrated in terms of a recently developed model of gravitation based on a non-Riemannian spacetime geometry.

  9. Optical heat flux gauge

    DOEpatents

    Noel, B.W.; Borella, H.M.; Cates, M.R.; Turley, W.D.; MacArthur, C.D.; Cala, G.C.

    1991-04-09

    A heat flux gauge is disclosed comprising first and second thermographic phosphor layers separated by a layer of a thermal insulator, wherein each thermographic layer comprises a plurality of respective thermographic sensors in a juxtaposed relationship with respect to each other. The gauge may be mounted on a surface with the first thermographic phosphor in contact with the surface. A light source is directed at the gauge, causing the phosphors to luminesce. The luminescence produced by the phosphors is collected and its spectra analyzed in order to determine the heat flux on the surface. First and second phosphor layers must be different materials to assure that the spectral lines collected will be distinguishable. 9 figures.

  10. Holographic Gauge Mediation

    SciTech Connect

    Benini, Francesco; Dymarsky, Anatoly; Franco, Sebastian; Kachru, Shamit; Simic, Dusan; Verlinde, Herman; /Princeton, Inst. Advanced Study

    2009-06-19

    We discuss gravitational backgrounds where supersymmetry is broken at the end of a warped throat, and the SUSY-breaking is transmitted to the Standard Model via gauginos which live in (part of) the bulk of the throat geometry. We find that the leading effect arises from splittings of certain 'messenger mesons,' which are adjoint KK-modes of the D-branes supporting the Standard Model gauge group. This picture is a gravity dual of a strongly coupled field theory where SUSY is broken in a hidden sector and transmitted to the Standard Model via a relative of semi-direct gauge mediation.

  11. Remote Spacecraft Attitude Control by Coulomb Charging

    NASA Astrophysics Data System (ADS)

    Stevenson, Daan

    The possibility of inter-spacecraft collisions is a serious concern at Geosynchronous altitudes, where many high-value assets operate in proximity to countless debris objects whose orbits experience no natural means of decay. The ability to rendezvous with these derelict satellites would enable active debris removal by servicing or repositioning missions, but docking procedures are generally inhibited by the large rotational momenta of uncontrolled satellites. Therefore, a contactless means of reducing the rotation rate of objects in the space environment is desired. This dissertation investigates the viability of Coulomb charging to achieve such remote spacecraft attitude control. If a servicing craft imposes absolute electric potentials on a nearby nonspherical debris object, it will impart electrostatic torques that can be used to gradually arrest the object's rotation. In order to simulate the relative motion of charged spacecraft with complex geometries, accurate but rapid knowledge of the Coulomb interactions is required. To this end, a new electrostatic force model called the Multi-Sphere Method (MSM) is developed. All aspects of the Coulomb de-spin concept are extensively analyzed and simulated using a system with simplified geometries and one dimensional rotation. First, appropriate control algorithms are developed to ensure that the nonlinear Coulomb torques arrest the rotation with guaranteed stability. Moreover, the complex interaction of the spacecraft with the plasma environment and charge control beams is modeled to determine what hardware requirements are necessary to achieve the desired electric potential levels. Lastly, the attitude dynamics and feedback control development is validated experimentally using a scaled down terrestrial testbed. High voltage power supplies control the potential on two nearby conductors, a stationary sphere and a freely rotating cylinder. The nonlinear feedback control algorithms developed above are implemented to

  12. Three-loop calculations in non-abelian gauge theories

    NASA Astrophysics Data System (ADS)

    Tarasov, O. V.; Vladimirov, A. A.

    2013-09-01

    A detailed description of the method for analytical evaluation of the three-loop contributions to renormalization group functions is presented. This method is employed to calculate the charge renormalization function and anomalous dimensions for non-Abelian gauge theories with fermions in the three-loop approximation. A three-loop expression for the effective charge of QCD is given. Charge renormalization effects in the SU(4)-supersymmetric gauge model is shown to vanish at this level. A complete list of required formulas is given in Appendix. The above-mentioned results of three-loop calculations were published by the present authors (with A.Yu. Zharkov and L.V. Avdeev) in 1980 in Physics Letters B. The present text, which treats the subject in more details and contains a lot of calculational techniques, was also published in 1980 as the JINR Communication E2-80-483.

  13. Infrared finite ghost propagator in the Feynman gauge

    SciTech Connect

    Aguilar, A. C.; Papavassiliou, J.

    2008-06-15

    We demonstrate how to obtain from the Schwinger-Dyson equations of QCD an infrared finite ghost propagator in the Feynman gauge. The key ingredient in this construction is the longitudinal form factor of the nonperturbative gluon-ghost vertex, which, contrary to what happens in the Landau gauge, contributes nontrivially to the gap equation of the ghost. The detailed study of the corresponding vertex equation reveals that in the presence of a dynamical infrared cutoff this form factor remains finite in the limit of vanishing ghost momentum. This, in turn, allows the ghost self-energy to reach a finite value in the infrared, without having to assume any additional properties for the gluon-ghost vertex, such as the presence of massless poles. The implications of this result and possible future directions are briefly outlined.

  14. Gauge invariant gluon spin operator for spinless nonlinear wave solutions

    NASA Astrophysics Data System (ADS)

    Lee, Bum-Hoon; Kim, Youngman; Pak, D. G.; Tsukioka, Takuya; Zhang, P. M.

    2017-04-01

    We consider nonlinear wave type solutions with intrinsic mass scale parameter and zero spin in a pure SU(2) quantum chromodynamics (QCD). A new stationary solution which can be treated as a system of static Wu-Yang monopole dressed in off-diagonal gluon field is proposed. A remarkable feature of such a solution is that it possesses a finite energy density everywhere. All considered nonlinear wave type solutions have common features: presence of the mass scale parameter, nonvanishing projection of the color fields along the propagation direction and zero spin. The last property requires revision of the gauge invariant definition of the spin density operator which is supposed to produce spin one states for the massless vector gluon field. We construct a gauge invariant definition of the classical gluon spin density operator which is unique and Lorentz frame independent.

  15. Stability of the Electroweak Vacuum: Gauge Independence and Advanced Precision

    NASA Astrophysics Data System (ADS)

    Bednyakov, A. V.; Kniehl, B. A.; Pikelner, A. F.; Veretin, O. L.

    2015-11-01

    We perform a manifestly gauge-independent analysis of the vacuum stability in the standard model including two-loop matching, three-loop renormalization group evolution, and pure QCD corrections through four loops. All these ingredients are exact, except that light-fermion masses are neglected. We in turn apply the criterion of nullifying the Higgs self-coupling and its beta function in the modified minimal-subtraction scheme and a recently proposed consistent method for determining the true minimum of the effective Higgs potential that also avoids gauge dependence. Exploiting our knowledge of the Higgs-boson mass, we derive an upper bound on the pole mass of the top quark by requiring that the standard model be stable all the way up to the Planck mass scale and conservatively estimate the theoretical uncertainty. This bound is compatible with the Monte Carlo mass quoted by the Particle Data Group at the 1.3 σ level.

  16. Pauli-Villars Regularization of Non-Abelian Gauge Theories

    NASA Astrophysics Data System (ADS)

    Hiller, J. R.

    2016-07-01

    As an extension of earlier work on QED, we construct a BRST-invariant Lagrangian for SU(N) Yang-Mills theory with fundamental matter, regulated by the inclusion of massive Pauli-Villars (PV) gluons and PV quarks. The underlying gauge symmetry for massless PV gluons is generalized to accommodate the PV-index-changing currents that are required by the regularization. Auxiliary adjoint scalars are used, in a mechanism due to Stueckelberg, to attribute mass to the PV gluons and the PV quarks. The addition of Faddeev-Popov ghosts then establishes a residual BRST symmetry. Although there are drawbacks to the approach, in particular the computational load of a large number of PV fields and a nonlocal interaction of the ghost fields, this formulation could provide a foundation for renormalizable nonperturbative solutions of light-front QCD in an arbitrary covariant gauge.

  17. Bound states in gauge theories as the Poincare group representations

    SciTech Connect

    Cherny, A. Yu.; Dorokhov, A. E.; Han, Nguyen Suan; Pervushin, V. N. Shilin, V. I.

    2013-03-15

    The bound-state generating functional is constructed in gauge theories. This construction is based on the Dirac Hamiltonian approach to gauge theories, the Poincare group classification of fields and their nonlocal bound states, and the Markov-Yukawa constraint of irreducibility. The generating functional contains additional anomalous creations of pseudoscalar bound states: para-positronium in QED and mesons inQCDin the two-gamma processes of the type of {gamma} + {gamma} {yields} {pi}{sub 0} +para-positronium. The functional allows us to establish physically clear and transparent relations between the perturbativeQCD to its nonperturbative low-energy model by means of normal ordering and the quark and gluon condensates. In the limit of small current quark masses, the Gell-Mann-Oakes-Renner relation is derived from the Schwinger-Dyson and Bethe-Salpeter equations. The constituent quark masses can be calculated from a self-consistent nonlinear equation.

  18. New results in perturbative QCD

    SciTech Connect

    Ellis, R.K.

    1985-11-01

    Three topics in perturbative QCD important for Super-collider physics are reviewed. The topics are: (2 2) jet phenomena calculated in O( sT); new techniques for the calculation of tree graphs; and colour coherence in jet phenomena. 31 refs., 6 figs.

  19. Heavy quark production and QCD

    SciTech Connect

    Purohit, M.V.

    1988-12-01

    Recent results on charm and beauty production in fixed target experiments are reviewed. Particular emphasis is placed on the recent results, on the trend favored by the data, on companies with the recently improved QCD predictions and on what may be expected in the near future. 35 refs., 5 figs.

  20. Nuclear reactions from lattice QCD

    DOE PAGES

    Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.

    2015-01-13

    In this study, one of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculationsmore » of some of the low-energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.« less

  1. Meson Resonances from Lattice QCD

    SciTech Connect

    Edwards, Robert G.

    2016-06-01

    There has been recent, significant, advances in the determination of the meson spectrum of QCD. Current efforts have focused on the development and application of finite-volume formalisms that allow for the determination of scattering amplitudes as well as resonance behavior in coupled channel systems. I will review some of these recent developments, and demonstrate the viability of the method in meson systems.

  2. QCD Spin Physics: Theoretical Overview

    SciTech Connect

    Vogelsang,W.

    2008-11-09

    We give an overview of some of the current activities and results in QCD spin physics. We focus on the helicity structure of the nucleon, where we highlight the results of a recent first global analysis of the helicity parton distributions, and on single-transverse spin asymmetries.

  3. Nuclear reactions from lattice QCD

    SciTech Connect

    Briceño, Raúl A.; Davoudi, Zohreh; Luu, Thomas C.

    2015-01-13

    In this study, one of the overarching goals of nuclear physics is to rigorously compute properties of hadronic systems directly from the fundamental theory of strong interactions, Quantum Chromodynamics (QCD). In particular, the hope is to perform reliable calculations of nuclear reactions which will impact our understanding of environments that occur during big bang nucleosynthesis, the evolution of stars and supernovae, and within nuclear reactors and high energy/density facilities. Such calculations, being truly ab initio, would include all two-nucleon and three- nucleon (and higher) interactions in a consistent manner. Currently, lattice QCD provides the only reliable option for performing calculations of some of the low-energy hadronic observables. With the aim of bridging the gap between lattice QCD and nuclear many-body physics, the Institute for Nuclear Theory held a workshop on Nuclear Reactions from Lattice QCD on March 2013. In this review article, we report on the topics discussed in this workshop and the path planned to move forward in the upcoming years.

  4. Lattice QCD in Background Fields

    SciTech Connect

    William Detmold, Brian Tiburzi, Andre Walker-Loud

    2009-06-01

    Electromagnetic properties of hadrons can be computed by lattice simulations of QCD in background fields. We demonstrate new techniques for the investigation of charged hadron properties in electric fields. Our current calculations employ large electric fields, motivating us to analyze chiral dynamics in strong QED backgrounds, and subsequently uncover surprising non-perturbative effects present at finite volume.

  5. Recent progress in lattice QCD

    SciTech Connect

    Sharpe, S.R.

    1992-12-01

    A brief overview of the status of lattice QCD is given, with emphasis on topics relevant to phenomenology. The calculation of the light quark spectrum, the lattice prediction of {alpha} {sub {ovr MS}} (M {sub Z}), and the calculation of f{sub B} are discussed. 3 figs., 3 tabs., 40 refs.

  6. Basics of QCD perturbation theory

    SciTech Connect

    Soper, D.E.

    1997-06-01

    This is an introduction to the use of QCD perturbation theory, emphasizing generic features of the theory that enable one to separate short-time and long-time effects. The author also covers some important classes of applications: electron-positron annihilation to hadrons, deeply inelastic scattering, and hard processes in hadron-hadron collisions. 31 refs., 38 figs.

  7. Cotunneling Drag Effect in Coulomb-Coupled Quantum Dots

    NASA Astrophysics Data System (ADS)

    Keller, A. J.; Lim, J. S.; Sánchez, David; López, Rosa; Amasha, S.; Katine, J. A.; Shtrikman, Hadas; Goldhaber-Gordon, D.

    2016-08-01

    In Coulomb drag, a current flowing in one conductor can induce a voltage across an adjacent conductor via the Coulomb interaction. The mechanisms yielding drag effects are not always understood, even though drag effects are sufficiently general to be seen in many low-dimensional systems. In this Letter, we observe Coulomb drag in a Coulomb-coupled double quantum dot and, through both experimental and theoretical arguments, identify cotunneling as essential to obtaining a correct qualitative understanding of the drag behavior.

  8. Holographic QCD integrated back to hidden local symmetry

    SciTech Connect

    Harada, Masayasu; Matsuzaki, Shinya; Yamawaki, Koichi

    2010-10-01

    We develop a previously proposed gauge-invariant method to integrate out an infinite tower of Kaluza-Klein (KK) modes of vector and axial-vector mesons in a class of models of holographic QCD (HQCD). The HQCD is reduced by our method to chiral perturbation theory with hidden local symmetry (HLS), having only the lowest KK mode identified as the HLS gauge boson. We take the Sakai-Sugimoto model as a concrete HQCD, and completely determine the O(p{sup 4}) terms as well as the O(p{sup 2}) terms from the Dirac-Born-Infeld part and the anomaly-related (intrinsic-parity odd) gauge-invariant terms from the Chern-Simons part. Effects of higher KK modes are fully included in these terms. To demonstrate the power of our method, we compute momentum dependences of several form factors, such as the pion electromagnetic form factors, and the {pi}{sup 0}-{gamma} and {omega}-{pi}{sup 0} transition form factors, compared with experiment, which was not achieved before due to the complication of handling infinite sums. We also study other anomaly-related quantities like {gamma}{sup *}-{pi}{sup 0}-{pi}{sup +}-{pi}{sup -} and {omega}-{pi}{sup 0}-{pi}{sup +}-{pi}{sup -} vertex functions.

  9. Vector meson electroproduction in QCD

    NASA Astrophysics Data System (ADS)

    Lu, Juan; Cai, Xian-Hao; Zhou, Li-Juan

    2012-08-01

    Based on the generalized QCD vector meson dominance model, we study the electroproduction of a vector meson off a proton in the QCD inspired eikonalized model. Numerical calculations for the total cross section σtot and differential cross section dσ/dt are performed for ρ, ω and varphi meson electroproduction in this paper. Since gluons interact among themselves (self-interaction), two gluons can form a glueball with quantum numbers IG, JPC = 0+,2++, decay width Γt ≈ 100 MeV, and mass of mG = 2.23 GeV. The three gluons can form a three-gluon colorless bound state with charge conjugation quantum number C = -1, called the Odderon. The mediators of interactions between projectiles (the quark and antiquark pair fluctuated from the virtual photon) and the proton target (a three-quark system) are the tensor glueball and the Odderon. Our calculated results in the tensor glueball and Odderon exchange model fit to the existing data successfully, which evidently shows that our present QCD mechanism is a good description of meson electroproduction off a proton. It should be emphasized that our mechanism is different from the theoretical framework of Block et al. We also believe that the present study and its success are important for the investigation of other vector meson electro- and photoproduction at high energies, as well as for searching for new particles such as tensor glueballs and Odderons, which have been predicted by QCD and the color glass condensate model (CGC). Therefore, in return, it can test the validity of QCD and the CGC model.

  10. An NLO QCD effective field theory analysis of W+W- production at the LHC including fermionic operators

    DOE PAGES

    Baglio, Julien; Dawson, Sally; Lewis, Ian M.

    2017-10-01

    We study the impact of anomalous gauge boson and fermion couplings on the production of W+W- pairs at the LHC. Helicity amplitudes are presented separately to demonstrate the sources of new physics contributions and the impact of QCD and electroweak corrections. The QCD corrections have important effects on the fits to anomalous couplings, in particular when one W boson is longitudinally polarized and the other is transversely polarized. In effective field theory language, we demonstrate that the dimension-6 approximation to constraining new physics effects in W+W- pair production fails at pT ~ 500 - 1000 GeV.

  11. Comparing the drag force on heavy quarks in N=4 super-Yang-Mills theory and QCD

    SciTech Connect

    Gubser, Steven S.

    2007-12-15

    Computations of the drag force on a heavy quark moving through a thermal state of strongly coupled N=4 super-Yang-Mills theory have appeared recently. I compare the strength of this effect between N=4 gauge theory and QCD, using the static force between external quarks to normalize the 't Hooft coupling. Comparing N=4 and QCD at fixed energy density then leads to a relaxation time of roughly 2 fm/c for charm quarks moving through a quark-gluon plasma at T=250 MeV. This estimate should be regarded as preliminary because of the difficulties of comparing two such different theories.

  12. Digital lattice gauge theories

    NASA Astrophysics Data System (ADS)

    Zohar, Erez; Farace, Alessandro; Reznik, Benni; Cirac, J. Ignacio

    2017-02-01

    We propose a general scheme for a digital construction of lattice gauge theories with dynamical fermions. In this method, the four-body interactions arising in models with 2 +1 dimensions and higher are obtained stroboscopically, through a sequence of two-body interactions with ancillary degrees of freedom. This yields stronger interactions than the ones obtained through perturbative methods, as typically done in previous proposals, and removes an important bottleneck in the road towards experimental realizations. The scheme applies to generic gauge theories with Lie or finite symmetry groups, both Abelian and non-Abelian. As a concrete example, we present the construction of a digital quantum simulator for a Z3 lattice gauge theory with dynamical fermionic matter in 2 +1 dimensions, using ultracold atoms in optical lattices, involving three atomic species, representing the matter, gauge, and auxiliary degrees of freedom, that are separated in three different layers. By moving the ancilla atoms with a proper sequence of steps, we show how we can obtain the desired evolution in a clean, controlled way.

  13. Extended gauge sectors

    SciTech Connect

    Rizzo, T.G.

    1995-02-01

    Present and future prospects for the discovery of new gauge bosons, Z{prime} and W{prime}, are reviewed. Particular attention is paid to hadron and e{sup +}e{sup {minus}} collider searches for the W{prime} of the Left-Right Symmetric Model.

  14. Neutron electric dipole moment from lattice QCD

    SciTech Connect

    Shintani, E.; Kanaya, K.; Aoki, S.; Ishizuka, N.; Kuramashi, Y.; Taniguchi, Y.; Ukawa, A.; Yoshie, T.; Kikukawa, Y.; Okawa, M.

    2005-07-01

    We carry out a feasibility study for the lattice QCD calculation of the neutron electric dipole moment (NEDM) in the presence of the {theta} term. We develop the strategy to obtain the nucleon EDM from the CP-odd electromagnetic form factor F{sub 3} at small {theta}, in which NEDM is given by lim{sub q{sup 2}}{sub {yields}}{sub 0}{theta}F{sub 3}(q{sup 2})/(2m{sub N}), where q is the momentum transfer and m{sub N} is the nucleon mass. We first derive a formula which relates F{sub 3}, a matrix element of the electromagnetic current between nucleon states, with vacuum expectation values of nucleons and/or the current. In the expansion of {theta}, the parity-odd part of the nucleon-current-nucleon three-point function contains contributions not only from the parity-odd form factors but also from the parity-even form factors multiplied by the parity-odd part of the nucleon two-point function, and, therefore, the latter contribution must be subtracted to extract F{sub 3}. We then perform an explicit lattice calculation employing the domain-wall quark action with the renormalization group improved gauge action in quenched QCD at a{sup -1}{approx_equal}2 GeV on a 16{sup 3}x32x16 lattice. At the quark mass m{sub f}a=0.03, corresponding to m{sub {pi}}/m{sub {rho}}{approx_equal}0.63, we accumulate 730 configurations, which allow us to extract the parity-odd part in both two- and three-point functions. Employing two different Dirac {gamma} matrix projections, we show that a consistent value for F{sub 3} cannot be obtained without the subtraction described above. We obtain F{sub 3}(q{sup 2}{approx_equal}0.58 GeV{sup 2})/(2m{sub N})=-0.024(5)e{center_dot}fm for the neutron and F{sub 3}(q{sup 2}{approx_equal}0.58 GeV{sup 2})/(2m{sub N})=0.021(6)e{center_dot}fm for the proton.

  15. Phases of N=1 Supersymmetric Chiral Gauge Theories

    SciTech Connect

    Craig, Nathaniel; Essig, Rouven; Hook, Anson; Torroba, Gonzalo; /SLAC /Stanford U., Phys. Dept.

    2012-02-17

    We analyze the phases of supersymmetric chiral gauge theories with an antisymmetric tensor and (anti)fundamental flavors, in the presence of a classically marginal superpotential deformation. Varying the number of flavors that appear in the superpotential reveals rich infrared chiral dynamics and novel dualities. The dualities are characterized by an infinite family of magnetic duals with arbitrarily large gauge groups describing the same fixed point, correlated with arbitrarily large classical global symmetries that are truncated nonperturbatively. At the origin of moduli space, these theories exhibit a phase with confinement and chiral symmetry breaking, an interacting nonabelian Coulomb phase, and phases where an interacting sector coexists with a sector that either s-confines or is in a free magnetic phase. Properties of these intriguing 'mixed phases' are studied in detail using duality and a-maximization, and the presence of superpotential interactions provides further insights into their formation.

  16. The story of the gauge.

    PubMed

    Pöll, J S

    1999-06-01

    Gauges are old measures of thickness. They originated in the British iron wire industry at a time when there was no universal unit of thickness. The sizes of the gauge numbers were the result of the process of wire-drawing and the nature of iron as a substance. Gauges were measured and described in fractions of an inch during the 19th century. In the UK, one gauge was standardised and legally enforced as the Standard Wire Gauge. One important reason for the standardisation of the gauge was the convenience of craftsmen. In the 20th century, the gauge was to be replaced with the introduction of the International System of Units. However, within the field of anaesthesia at the threshold of the 21st century, the gauge seems hard to remove from the minds of craftsmen like anaesthetists.

  17. Setting the Renormalization Scale in QCD: The Principle of Maximum Conformality

    SciTech Connect

    Brodsky, Stanley J.; Di Giustino, Leonardo; /SLAC

    2011-08-19

    A key problem in making precise perturbative QCD predictions is the uncertainty in determining the renormalization scale {mu} of the running coupling {alpha}{sub s}({mu}{sup 2}): The purpose of the running coupling in any gauge theory is to sum all terms involving the {beta} function; in fact, when the renormalization scale is set properly, all non-conformal {beta} {ne} 0 terms in a perturbative expansion arising from renormalization are summed into the running coupling. The remaining terms in the perturbative series are then identical to that of a conformal theory; i.e., the corresponding theory with {beta} = 0. The resulting scale-fixed predictions using the 'principle of maximum conformality' (PMC) are independent of the choice of renormalization scheme - a key requirement of renormalization group invariance. The results avoid renormalon resummation and agree with QED scale-setting in the Abelian limit. The PMC is also the theoretical principle underlying the BLM procedure, commensurate scale relations between observables, and the scale-setting method used in lattice gauge theory. The number of active flavors nf in the QCD {beta} function is also correctly determined. We discuss several methods for determining the PMC/BLM scale for QCD processes. We show that a single global PMC scale, valid at leading order, can be derived from basic properties of the perturbative QCD cross section. The elimination of the renormalization scheme ambiguity using the PMC will not only increase the precision of QCD tests, but it will also increase the sensitivity of collider experiments to new physics beyond the Standard Model.

  18. Spin chains in {N} = {2} superconformal theories from the {{Z}_2} quiver to superconformal QCD

    NASA Astrophysics Data System (ADS)

    Gadde, Abhijit; Pomoni, Elli; Rastelli, Leonardo

    2012-06-01

    In this paper we find preliminary evidence that {N} = {2} superconformal QCD, the SU( N c ) SYM theory with N f = 2 N c fundamental hypermultiplets, might be integrable in the large N Veneziano limit. We evaluate the one-loop dilation operator in the scalar sector of the {N} = {2} superconformal quiver with SU( N c ) × SU( N č ) gauge group, for N c ≡ N č . Both gauge couplings g and ǧ are exactly marginal. This theory interpolates between the {{Z}_2} orbifold of {N} = {4} SYM, which corresponds to ǧ = g, and {N} = {2} superconformal QCD, which is obtained for ǧ → 0. The planar one-loop dilation operator takes the form of a nearest-neighbor spin-chain Hamiltonian. For superconformal QCD the spin chain is of novel form: besides the color-adjoint fields φ_b^a, which occupy individual sites of the chain, there are "dimers" Q_i^aoverline Q_b^i of flavor-contracted fundamental fields, which occupy two neighboring sites. We solve the two-body scattering problem of magnon excitations and study the spectrum of bound states, for general ǧ/g. The dimeric excitations of superconformal QCD are seen to arise smoothly for ǧ → 0 as the limit of bound wavefunctions of the interpolating theory. Finally we check the Yang-Baxter equation for the two-magnon S-matrix. It holds as expected at the orbifold point ǧ = g. While violated for general ǧ ≠ g, it holds again in the limit ǧ → 0, hinting at one-loop integrability of planar {N} = {2} superconformal QCD.

  19. Deep inelastic scattering cross sections from the gauge/string duality

    NASA Astrophysics Data System (ADS)

    Koile, Ezequiel; Kovensky, Nicolas; Schvellinger, Martin

    2015-12-01

    Differential cross sections of deep inelastic scattering of charged leptons from hadrons are investigated by using the gauge/string duality. We consider vector mesons derived from different holographic dual models obtaining a general expression. We focus on the strongly coupled regime of dual gauge theories for different values of the Bjorken parameter. We find new predictions which are particularly interesting for differential scattering cross sections of polarized leptons scattered off polarized vector mesons. We also carry out a detailed comparison of the moments of the structure functions with lattice QCD results.

  20. Envelope representations for screened Coulomb potentials

    NASA Astrophysics Data System (ADS)

    Hall, Richard L.

    1985-07-01

    We study the discrete eigenvalues Enl of the Schrödinger Hamiltonian H=-(1/2)Δ+V(r), where V(r)=g(-1/r) is an increasing concave transformation of the Coulomb potential, and n is the principal (radial) quantum number. It is demonstrated by the method of potential envelopes that upper bounds are provided by the simple formula Enl<= mins>0 \\{(1/2)s+V((n+l)/s1/2)\\}, where s is a real variable. Numerical results are compared with previous work for two specific screened Coulomb potentials. In the case of the Yukawa potential V(r)=-(v/r)exp(-λr), it is shown that the inequality (n+l)2λ/v<2/e is sufficient to guarantee the existence of the eigenvalue Enl: In the case of S states, sharp upper and lower bounds are also provided by a different method.