Sample records for spurions

  1. Effective action of softly broken supersymmetric theories

    SciTech Connect

    Nibbelink, Stefan Groot; Nyawelo, Tino S.


    We study the renormalization of (softly) broken supersymmetric theories at the one loop level in detail. We perform this analysis in a superspace approach in which the supersymmetry breaking interactions are parametrized using spurion insertions. We comment on the uniqueness of this parametrization. We compute the one loop renormalization of such theories by calculating superspace vacuum graphs with multiple spurion insertions. To perform this computation efficiently we develop algebraic properties of spurion operators, that naturally arise because the spurions are often surrounded by superspace projection operators. Our results are general apart from the restrictions that higher super covariant derivative terms and some finite effects due to noncommutativity of superfield dependent mass matrices are ignored. One of the soft potentials induces renormalization of the Kaehler potential.

  2. Exotic nonrelativistic string

    SciTech Connect

    Casalbuoni, Roberto; Gomis, Joaquim; Longhi, Giorgio


    We construct a classical nonrelativistic string model in 3+1 dimensions. The model contains a spurion tensor field that is responsible for the noncommutative structure of the model. Under double-dimensional reduction the model reduces to the exotic nonrelativistic particle in 2+1 dimensions.

  3. General very special relativity in Finsler cosmology

    SciTech Connect

    Kouretsis, A. P.; Stathakopoulos, M.; Stavrinos, P. C.


    General very special relativity (GVSR) is the curved space-time of very special relativity (VSR) proposed by Cohen and Glashow. The geometry of general very special relativity possesses a line element of Finsler geometry introduced by Bogoslovsky. We calculate the Einstein field equations and derive a modified Friedmann-Robertson-Walker cosmology for an osculating Riemannian space. The Friedmann equation of motion leads to an explanation of the cosmological acceleration in terms of an alternative non-Lorentz invariant theory. A first order approach for a primordial-spurionic vector field introduced into the metric gives back an estimation of the energy evolution and inflation.

  4. Leptoquark flavor patterns & B decay anomalies

    NASA Astrophysics Data System (ADS)

    Hiller, Gudrun; Loose, Dennis; Schönwald, Kay


    Flavor symmetries that explain masses and mixings of the standard model fermions dictate flavor patterns for the couplings of scalar and vector leptoquarks to the standard model fermions. A generic feature is that couplings to SU(2)-doublet leptons are suppressed at least by one spurion of the discrete non-abelian symmetry breaking, responsible for neutrino mixing, while couplings to charged lepton singlets can be order one. We obtain testable patterns including those that predominantly couple to a single lepton flavor, or two, or in a skewed way. They induce lepton non-universality, which we contrast to current anomalies in B-decays. We find maximal effects in R D and {R_D}{^{ast }} at the level of ˜10 percent and few percent, respectively, while leptoquark effects in {R_K}{^{(ast )}} can reach order few×10 percent. Predictions for charm and kaon decays and μ - e conversion are worked out.

  5. Shortening anomalies in supersymmetric theories

    NASA Astrophysics Data System (ADS)

    Gomis, Jaume; Komargodski, Zohar; Ooguri, Hirosi; Seiberg, Nathan; Wang, Yifan


    We present new anomalies in two-dimensional N=(2,2) superconformal theories. They obstruct the shortening conditions of chiral and twisted chiral multiplets at coincident points. This implies that marginal couplings cannot be promoted to background superfields in short representations. Therefore, standard results that follow from N=(2,2) spurion analysis are invalidated. These anomalies appear only if supersymmetry is enhanced beyond N=(2,2) . These anomalies explain why the conformal manifolds of the K3 and T 4 sigma models are not Kähler and do not factorize into chiral and twisted chiral moduli spaces and why there are no N=(2,2) gauged linear sigma models that cover these conformal manifolds. We also present these results from the point of view of the Riemann curvature of conformal manifolds.

  6. Superconductivity due to soft super-symmetry breaking

    NASA Astrophysics Data System (ADS)

    S. Rajput, Balwant


    Revisiting the super-symmetric dyons in N = 2 super-symmetric theory and analyzing the possible soft breaking of N = 2 super-symmetric Yang Mills theory to N = 0 by making the dynamically generated mass scale ∧ a function of dilation spurion, it has been demonstrated that the scalar and auxiliary components of pre-potential, constructed in terms of dilation, are frozen to be constant to generate soft breaking of N = 2 theory and it has been shown that, as soon as these soft breaking terms are turned on, monopole condensation appears and we get a unique ground state and the superconducting phase. It is also shown that in this soft breaking of N = 2 super-symmetry, the superconductivity phase occurs due to condensation of monopoles only and the dyons do not condensate near the real u -plane.

  7. N=2 supersymmetric Yang-Mills theories and Whitham integrable hierarchies

    NASA Astrophysics Data System (ADS)

    Edelstein, José D.; Mas, Javier


    We review recent work on the study of N=2 super Yang-Mills theory with gauge group SU(N) from the point of view of the Whitham hierarchy, mainly focusing on three main results: (i) We develop a new recursive method to compute the whole instanton expansion of the low-energy effective prepotential; (ii) We interpret the slow times of the hierarchy as additional couplings and promote them to spurion superfields that softly break N=2 supersymmetry down to N=0 through deformations associated to higher Casimir operators of the gauge group; (iii) We show that the Seiberg-Witten-Whitham equations provide a set of non-trivial constraints on the form of the strong coupling expansion in the vicinity of the maximal singularities. We use them to check a proposal that we make for the value of the off-diagonal couplings at those points of the moduli space.

  8. Comments on Gaugino Screening

    SciTech Connect

    Cohen, Timothy; Hook, Anson; Wecht, Brian


    Gauge mediated models of supersymmetry breaking often exhibit 'gaugino screening,' where to leading order in F, gaugino masses are unaffected by higher dimensional Kahler potential interactions between the supersymmetry breaking spurion and the messengers. We provide a derivation of this phenomenon which utilizes the gaugino counterterm originally proposed in the context of anomaly mediation by Dine and Seiberg. We argue that this counterterm is present when there are non-zero messenger F-terms, and can cancel the leading order Feynman diagram contribution to the gaugino mass. We provide a nontrivial check of the regulator independence of our results by performing the computation using both dimensional reduction and Pauli-Villars. This analysis reconciles an apparent contradiction between diagrammatics and analytic continuation into superspace.

  9. Standard model fermions and N =8 supergravity

    NASA Astrophysics Data System (ADS)

    Meissner, Krzysztof A.; Nicolai, Hermann


    In a scheme originally proposed by Gell-Mann, and subsequently shown to be realized at the SU (3 )×U (1 ) stationary point of maximal gauged SO(8) supergravity by Warner and one of the present authors, the 48 spin-1/2 fermions of the theory remaining after the removal of eight Goldstinos can be identified with the 48 quarks and leptons (including right-chiral neutrinos) of the Standard model, provided one identifies the residual SU(3) with the diagonal subgroup of the color group SU (3 )c and a family symmetry SU (3 )f . However, there remained a systematic mismatch in the electric charges by a spurion charge of ±1/6 . We here identify the "missing" U(1) that rectifies this mismatch, and that takes a surprisingly simple, though unexpected form.

  10. Universal contributions to scalar masses from five dimensional supergravity

    NASA Astrophysics Data System (ADS)

    Dudas, Emilian; von Gersdorff, Gero


    We compute the effective Kahler potential for matter fields in warped compactifications, starting from five dimensional gauged supergravity, as a function of the matter fields localization. We show that truncation to zero modes is inconsistent and the tree-level exchange of the massive gravitational multiplet is needed for consistency of the four-dimensional theory. In addition to the standard Kahler coming from dimensional reduction, we find the quartic correction coming from integrating out the gravity multiplet. We apply our result to the computation of scalar masses, by assuming that the SUSY breaking field is a bulk hypermultiplet. In the limit of extreme opposite localization of the matter and the spurion fields, we find zero scalar masses, consistent with sequestering arguments. Surprisingly enough, for all the other cases the scalar masses are tachyonic. This suggests the holographic interpretation that a CFT sector always generates operators contributing in a tachyonic way to scalar masses. Viability of warped supersymmetric compactifications necessarily asks then for additional contributions. We discuss the case of additional bulk vector multiplets with mixed boundary conditions, which is a particularly simple and attractive way to generate large positive scalar masses. We show that in this case successful fermion mass matrices implies highly degenerate scalar masses for the first two generations of squarks and sleptons.

  11. Minimally allowed beta beata 0_nu rates from approximate flavor symmetries

    SciTech Connect

    Jenkins, James


    Neutrinoless double beta decay ({beta}{beta}0{nu}) is the only realistic probe of Majorana neutrinos. In the standard scenario, dominated by light neutrino exchange, the process amplitude is proportional to m{sub ee} , the e - e element of the Majorana mass matrix. This is expected to hold true for small {beta}{beta}{nu} rates ({Gamma}{sub {beta}{beta}0{nu}}), even in the presence of new physics. Naively, current data allows for vanishing m{sub ee} , but this should be protected by an appropriate flavor symmetry. All such symmetries lead to mass matrices inconsistent with oscillation phenomenology. Hence, Majorana neutrinos imply nonzero {Gamma}{sub {beta}{beta}0{nu}}. I perform a spurion analysis to break all possible abelian symmetries that guarantee {Gamma}{sub {beta}{beta}0{nu}} = 0 and search for minimally allowed m{sub ee} values. Specifically, I survey 259 broken structures to yield m{sub ee} values and current phenomenological constraints under a variety of scenarios. This analysis also extracts predictions for both neutrino oscillation parameters and kinematic quantities. Assuming reasonable tuning levels, I find that m{sub ee} > 4 x 10{sup -6} eV at 99% confidence. Bounds below this value would indicate the Dirac neutrino nature or the existence of new light (eV-MeV scale) degrees of freedom that can potentially be probed elsewhere. This limit can be raised by improvements in neutrino parameter measurements, particularly of the reactor mixing angle, depending on the best fit parameter values. Such improvements will also significantly constrain the available model space and aid in future constructions.

  12. A Domino Theory of Flavor

    SciTech Connect

    Graham, Peter W.; Rajendran, Surjeet


    We argue that the fermion masses and mixings are organized in a specific pattern. The approximately equal hierarchies between successive generations, the sizes of the mixing angles, the heaviness of just the top quark, and the approximate down-lepton equality can all be accommodated by many flavor models but can appear ad hoc. We present a simple, predictive mechanism to explain these patterns. All generations are treated democratically and the flavor symmetries are broken collectively by only two allowed couplings in flavor-space, a vector and matrix, with arbitrary {Omicron}(1) entries. Repeated use of these flavor symmetry breaking spurions radiatively generates the Yukawa couplings with a natural hierarchy. We demonstrate this idea with two models in a split supersymmetric grand unified framework, with minimal additional particle content at the unification scale. Although flavor is generated at the GUT scale, there are several potentially testable predictions. In our minimal model the usual prediction of exact b-{tau} unification is replaced by the SU(5) breaking relation m{sub {tau}}/m{sub b} = 3/2, in better agreement with observations. Other SU(5) breaking effects in the fermion masses can easily arise directly from the flavor model itself. The symmetry breaking that triggers the generation of flavor necessarily gives rise to an axion, solving the strong CP problem. These theories contain long-lived particles whose decays could give striking signatures at the LHC and may solve the primordial Lithium problems. These models also give novel proton decay signatures which can be probed by the next generation of experiments. Measurement of the various proton decay channels directly probes the flavor symmetry breaking couplings. In this scenario the Higgs mass is predicted to lie in a range near 150 GeV.

  13. Techni-Dilaton Signatures at LHC

    NASA Astrophysics Data System (ADS)

    Matsuzaki, S.; Yamawaki, K.


    We explore discovery signatures of techni-dilaton (TD) at LHC. The TD was predicted long ago as a composite pseudo Nambu-Goldstone boson (pNGB) associated with the spontaneous breaking of the approximate scale symmetry in the walking technicolor (WTC) (initially dubbed ``scale-invariant technicolor''). Being pNGB, whose mass arises from the explicit scale-symmetry breaking due to the spontaneous breaking itself (dynamical mass generation), the TD as a composite scalar should have a mass M_{TD} lighter than other techni-hadrons, say M_{TD} ≃ 600 GeV for the typical WTC model, which is well in the discovery range of the ongoing LHC experiment. We develop a spurion method of nonlinear realization to calculate the TD couplings to the standard model (SM) particles and explicitly evaluate the TD LHC production cross sections at √{s} = 7 TeV times the branching ratios in terms of M_{TD} as an input parameter for the region 200 GeV < M_{TD} < 1000 GeV in the typical WTC models. It turns out that the TD signatures are quite different from those of the SM Higgs: In the one-doublet model (1DM) all the cross sections including the WW/ZZ mode are suppressed compared to those of the SM Higgs due to the suppressed TD couplings, while in the one-family model (1FM) all those cross sections get highly enhanced because of the presence of extra colored fermion (techni-quark) contributions. We compare the {TD} → WW/ZZ signature with the recent ATLAS and CMS bounds and find that in the case of 1DM the signature is consistent over the whole mass range 200 GeV < M_{TD} < 1000 GeV due to the large suppression of TD couplings, and by the same token the signal is too tiny for the TD to be visible through this channel at LHC. As for the 1FMs, on the other hand, a severe constraint is given on the TD mass to exclude the TD with mass ≲ 600 GeV, which, however, would imply an emergence of somewhat dramatic excess as the TD signature at 600 GeV ≲ M_{TD} < 1000 GeV in the near future. We

  14. Adventures in high energy theory and phenomenology

    NASA Astrophysics Data System (ADS)

    Robinson, Dean Jonathan

    -zero widths of the particles. We derive explicit formulae for differential decay rates involving both non-zero widths and oscillation, and show that in the case where the mass difference between the intermediate particles is of the order of their widths, both oscillation and width effects are important. An examination of the physical observables contained in these differential decay rates is also provided. We calculate differential decay rates for cases in which the intermediate particles are either scalars or fermions. Finally, we present flavor SU(3) sum rules for D → PP and D → PV decay amplitudes, that are valid to second order in symmetry breaking by the strange quark mass spurion. Decay rate sum rules are also computed to this order. Particular attention is given to sum rules arising from the isospin and U-spin subgroups, the former providing sensitive tests for alternative sources of SU(3) breaking. We apply the latter together with the postulated DeltaU = 0 rule for the large penguin picture to predict the ratio and difference of the direct CP asymmetries for D → KK* and D → pirho.