Electroweak meson production reaction in the nucleon resonance region
Sato, Toru
2015-10-15
We report on our recent study of the the neutrino-nucleon reaction in the nucleon resonance region. The dynamical reaction model of meson production reaction on the nucleon for the pion and photon induced reaction has been developed in order to investigate the spectrum of nucleon excited state. We have extended this model in order to describe the weak meson production reactions with the πN, ηN, KΛ, KΣ and ππN final states. We also studied the role of the final state interaction in the photon and the neutrino induced pion production reaction on the deuteron around the Δ(1232) resonance region.
Photon- and meson-induced reactions on the nucleon
NASA Astrophysics Data System (ADS)
Feuster, T.; Mosel, U.
1999-01-01
Starting from a unitary effective Lagrangian model for the meson-nucleon scattering developed in T. Feuster and U. Mosel, Phys. Rev. 58, 457 (1998), we come to a unified description of both meson scattering and photon-induced reactions on the nucleon. To this end the photon is added perturbatively, yielding both Compton scattering and meson photoproduction amplitudes. In a simultaneous fit to all available data the parameters of the nucleon resonances are extracted. We find that a global fit to the data of the various channels involving the final states γN, πN, ππN, ηN, and KΛ is possible. Especially in eta photoproduction a readjustment of the masses and widths found in the fits to hadronic reactions alone is necessary to describe the data. Only for the D13(1520) do we find a possible disagreement for the helicity couplings extracted using the combined data set and pion photoproduction multipoles alone. The model dependence introduced by the restoration of gauge invariance is discussed and found to be significant mainly for resonances with small helicity couplings.
X (3872) production from reactions involving D and D* mesons
NASA Astrophysics Data System (ADS)
Martínez Torres, A.; Khemchandani, K. P.; Navarra, F. S.; Nielsen, M.; Abreu, Luciano M.
2015-07-01
In this proceeding we show the results found for the cross sections of the processes D → πX(3872), *D → πX(3872) and *D* → πX(3872), information needed for calculations of the X (3872) abundance in heavy ion collisions. Our formalism is based on the generation of X(3872) from the interaction of the hadrons 0D*0 — c.c, D-D*+ — c.c and D-sD*+s — c.c. The evaluation of the cross section associated with processes having D* meson(s) involves an anomalous vertex, X*D*, which we have determined by considering triangular loops motivated by the molecular nature of X (3872). We find that the contribution of this vertex is important. Encouraged by this finding we estimate the X*D* coupling, which turns out to be 1.95 ± 0.22. We then use it to obtain the cross section for the reaction *D* → πX and find that the X*D* vertex is also relevant in this case. We also discuss the role of the charged components of X in the determination of the production cross sections.
Effect of in-medium parameters of ρ meson in its photoproduction reactions on nuclei
Das, Swapan
2015-03-15
There exist model calculations showing the modification of the hadronic parameters of ρ meson in the nuclear environment. From these parameters, we extract the ρ-meson-nucleus optical potential and show the medium effect due to this potential on the ρ-meson mass distribution spectra in the photonuclear reactions. The calculated results reproduced reasonably the measured e{sup +}e{sup −} invariant mass, i.e., ρ-meson mass, distribution spectra in γ, ρ{sup 0} → e{sup +}e{sup −} reactions on nuclei.
Nucleon resonances in exclusive reactions of photo- and electroproduction of mesons
Skorodumina, Iu. A.; Burkert, V. D.; Golovach, E. N.; Gothe, R. W.; Isupov, E. L.; Ishkhanov, B. S.; Mokeev, V. I.; Fedotov, G. V.
2015-11-01
Methods for extracting nucleon resonance parameters from experimental data are reviewed. The formalism for the description of exclusive reactions of meson photo- and electroproduction off nucleons is discussed. Recent experimental data on exclusive meson production in the scattering of electrons and photons off protons are analyzed.
Experimental study of η meson photoproduction reaction at MAMI
NASA Astrophysics Data System (ADS)
Kashevarov, V. L.
2015-06-01
New data for the differential cross sections, polarization observables T, F, and E in the reaction of η photoproduction on proton from the threshold up to a center-of-mass energy of W=1.9 GeV are presented. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. The polarization measurements were made using a frozen-spin butanol target and circularly polarized photon beam. The results are compared to existing experimental data and different PWA predictions. The data solve a long-standing problem related the angular dependence of older T data close to threshold. The unexpected relative phase motion between s- and d-wave amplitudes required by the old data is not confirmed. At higher energies, all model predictions fail to reproduce the new polarization data indicating a significant impact on our understanding of the underlying dynamics of η meson photoproduction. Furthermore, we present a fit of the new data and existing data from GRAAL for ∑ asymmetry based on an expansion in terms of associated Legendre polynomials. A Legendre decomposition shows the sensitivity to small partialwave contributions. The sensitivity of the Legendre coefficients to the nucleon resonance parameters is shown using the ηMAID isobar model.
Dynamical coupled-channels study of meson production reactions from EBAC@Jlab
Hiroyuki Kamano
2011-10-01
We present the current status of a combined and simultaneous analysis of meson production reactions based on a dynamical coupled-channels (DCC) model, which is conducted at Excited Baryon Analysis Center (EBAC) of Jefferson Lab.
Dynamical coupled-channels study of meson production reactions from EBACatJLab
Kamano, Hiroyuki
2011-10-24
We present the current status of a combined and simultaneous analysis of meson production reactions based on a dynamical coupled-channels (DCC) model, which is conducted at Excited Baryon Analysis Center (EBAC) of Jefferson Lab.
Extraction of Nucleon Resonances From Global Analysis of Meson Production Reactions at EBAC
Hiroyuki Kamano
2011-10-01
We report the current status of exploring the dynamical aspect of the excited nucleon states through the comprehensive coupled-channels analysis of meson production reactions at the Excited Baryon Analysis Center of Jefferson Lab.
Light meson decays from photon-induced reactions with CLAS
NASA Astrophysics Data System (ADS)
Kunkel, Michael C.
2016-05-01
Photo-production experiments with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Laboratory produce data sets with unprecedented statistics for light mesons. With these data sets, measurements of transition form factors for η, ω, and η' mesons via conversion decays can be performed using the invariant mass distribution of the final state dileptons. Tests of fundamental symmetries and information on the light quark mass difference can be performed using a Dalitz plot analysis of the meson decay. An overview of the first results, from existing CLAS data, and future prospects within the newly upgraded CLAS12 apparatus are given.
Dynamical Coupled-Channel Model of Meson Production Reactions in the Nucleon Resonance Region
T.-S. H. Lee; A. Matsuyama; T. Sato
2006-11-15
A dynamical coupled-channel model is presented for investigating the nucleon resonances (N*) in the meson production reactions induced by pions and photons. Our objective is to extract the N* parameters and to investigate the meson production reaction mechanisms for mapping out the quark-gluon substructure of N* from the data. The model is based on an energy-independent Hamiltonian which is derived from a set of Lagrangians by using a unitary transformation method.
Light Meson Decays from Photon-Induced Reactions with CLAS
NASA Astrophysics Data System (ADS)
Kunkel, Michael; CLAS Collaboration; Light Meson Decay (LMD) Team
2015-04-01
Photo-production experiments with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Laboratory produce data sets with unprecedented statistics of light mesons. With these data sets, measurements of transition form factors for η, ω, and η ' via conversion decays can be performed using a line shape analysis on the invariant mass of the final state dileptons. Tests of fundamental symmetries and information on the light quark mass difference can be performed using a Dalitz plot analysis of the meson decay. In addition, the data allows for a search for dark matter, such as the heavy photon via conversion decays of light mesons and physics beyond the Standard Model can be searched for via invisible decays of η mesons. An overview of the first results and future prospects will be given.
Medium Modi cation on Vector Mesons Observed in 12 GeV p + A Reactions
NASA Astrophysics Data System (ADS)
Naruki, M.; En'yo, H.; Muto, R.; Tabaru, T.; Yokkaichi, S.; Fukao, Y.; Funahashi, H.; Ishino, M.; Kanda, H.; Kitaguchi, M.; Mihara, S.; Miwa, K.; Miyashita, T.; Murakami, T.; Nakura, T.; Sakuma, F.; Togawa, M.; Yamada, S.; Yoshimura, Y.; Chiba, J.; Ieiri, M.; Sasaki, O.; Sekimoto, M.; Tanaka, K. H.; Hamagaki, H.; Kek-Ps E325 Collaboration
2006-11-01
The invariant mass spectra of e+e- pairs produced in 12 GeV p+A reactions are measured at the KEK-PS. We observed a significant enhancement over the known hadronic sources on the low-mass side of the ω meson peak. The 95 % C.L. allowed parameter regions for ρ/ω ratio are obtained as ρ/ω < 0.15 and ρ/ω < 0.31 for C and Cu targets, respectively. As for the φ meson, the data obtained with a Cu target revealed a significant excess on the low-mass side of the φ meson peak mainly in the βγφ < 1.25 region.
Anisovich, V. V. Sarantsev, A. V.
2009-11-15
We present technical aspects of the fitting procedure given in the paper by V.V. Anisovich and A.V. Sarantsev 'The analysis of reactions {pi}N {yields} two mesons + N within reggeon exchanges. Fit and results.'
Meson structure in soft hadronic reactions at COMPASS
Colantoni, M.
2006-02-11
The measurement of the electric ({alpha}-bar{pi}) and magnetic ({beta}-bar{pi}) pion polarizabilities supplies a significant test of QCD predictions in particular in the framework of the chiral perturbation theory.In this perspective we have measured with the COMPASS spectrometer the t-dependence of the cross section for the reactions: {pi}- + Z {yields} {pi}- + Z + {gamma}, and {mu}- + Z {yields} {mu}- + Z + {gamma} selecting events corresponding to the Compton {pi}{gamma} and {mu}{gamma} scattering respectively. From a fit of the data of the first reaction we can extract {alpha}-bar{pi} and {beta}-bar{pi}, from those of the second the point-like contribution. This procedure minimizes the systematic errors. Details on the experiment and the present status of the analysis of the data collected in 2004 will be discussed.
Role of pentaquark components in ϕ meson production proton-antiproton annihilation reactions
NASA Astrophysics Data System (ADS)
Srisuphaphon, S.; Kaewsnod, A.; Limphirat, A.; Khosonthongkee, K.; Yan, Y.
2016-02-01
The pentaquark component uuds s ¯ is included in the proton wave functions to study ϕ meson production proton-antiproton annihilation reactions. With all possible configurations of the uuds subsystem proposed for describing the strangeness spin and magnetic moment of the proton, we estimate the branching ratios of the annihilation reactions at rest p p ¯→ϕ X (X =π0,η ,ρ0,ω ) from atomic p p ¯ S - and P -wave states by using effective quark line diagrams incorporating the 3P0 model. The best agreement of theoretical prediction with the experimental data is found when the pentaquark configuration of the proton wave function takes the flavor-spin symmetry [4] FS[22] F[22] S .
Nakayama, K.; Love, W.G.
2005-09-01
The most general spin structures of the spin-1/2 baryon and spinless meson production operator for both photon and nucleon induced reactions are derived from the partial-wave expansions of these reaction amplitudes. The present method provides the coefficients multiplying each spin operator in terms of the partial-wave matrix elements. The result should be useful in studies of these reactions based on partial-wave analyses, especially, when spin observables are considered.
Extraction of Meson Resonances from Three-pions Photo-production Reactions
S. X. Nakamura, H. Kamano, T.-S. H. Lee, T. Sato
2012-12-01
We have investigated the model dependence of meson resonance properties extracted from the Dalitz-plot analysis of the three-pions photoproduction reactions on the nucleon. Within a unitary model developed in Phys. Rev. D 84, 114019 (2011), we generate Dalitz-plot distributions as data to perform an isobar model fit that is similar to most of the previous analyses of three-pion production reactions. It is found that the resonance positions from the two models agree well when both fit the data accurately, except for the resonance poles near branch points. The residues of the resonant amplitudes extracted from the two models and by the usual Breit-Wigner procedure agree well only for the isolated resonances with narrow widths. For overlapping resonances, most of the extracted residues could be drastically different. Our results suggest that even with high precision data, the resonance extraction should be based on models within which the amplitude parametrization is constrained by three-particle unitarity condition.
Medium modifications of light vector mesons in photoproduction reactions at Jlab
Djalali, Chaden; Wood, Michael; Nasseripour, Rakhsha; Weygand, Dennis
2008-10-01
DOI: http://dx.doi.org/10.1088/0954-3899/35/10/104035
Theoretical calculations predict the modification of properties of vector mesons, such as a shift in their masses and/or broadening of their widths in dense nuclear matter. These effects can be related to partial restoration of chiral symmetry at high density or temperature. The light vector mesons (rho, omega, and phi) were photo-produced on H-2, C, Ti, Fe, and Pb targets at the Thomas Jefferson National Laboratory using the CEBAF Large Acceptance Spectrometer (CLAS). The data were taken with a beam of tagged photons with energies up to 4 GeV . The properties of the rho vector meson at normal nuclear densities and zero temperature,were investigated via their rare leptonic decay to e+e?. This decay channel is preferred over hadronic modes in order to eliminate final state interactions in the nuclear matter. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing techn
Search for φ-Meson Nuclear Bound States in the overline{p} + ^{A}Z → φ + ^{A-1}_{φ}(Z-1) Reaction
NASA Astrophysics Data System (ADS)
Bühler, P.; Curceanu, C.; Guaraldo, C.; Hartmann, O.; Hicks, K.; Iwasaki, M.; Ishiwatari, T.; Kienle, P.; Marton, J.; Muto, R.; Niiyama, M.; Noumi, H.; Ohnishi, H.; Okada, S.; Vidal, A.; Sakaguchi, A.; Sakuma, F.; Sawada, S.; Sirghi, D.; Sirghi, F.; Suzuki, K.; Tsukada, K.; Tedeschi, D. J.; Doce, O.; Widmann, E.; Yokkaichi, S.; Zmeskal, J.; J-Parc P29 Collaboration
We propose to study in-medium mass modification of the φ mesonusing the formation of φ meson bound state. We demonstrate that a clear missing-mass spectrum can be obtained efficiently by (overline{p}, φ) spectroscopy together with the Λ tagging, using the primary reaction channel overline{p} p → φ φ. A systematic study over several nuclear targets will yield a unique, definitive and precise determination of the in-medium mass modification of the vector meson φ (s overline{s}).
Investigation of near-threshold eta-meson production in the reaction {pi}{sup -}p{yields} {eta}n
Bayadilov, D. E.; Beloglazov, Yu. A.; Gridnev, A. B.; Kozlenko, N. G.; Kruglov, S. P.; Kulbardis, A. A.; Lopatin, I. V.; Novinskiy, D. V.; Radkov, A. K.; Sumachev, V. V.; Filimonov, E. A.; Shvedchikov, A. V.
2012-08-15
Differential and total cross sections for eta-meson production in the reaction {pi}{sup -}p {yields} {eta}n were measured within the experimental program eta-meson physics implemented in the pion channel of the synchrocyclotron of the Petersburg Nuclear Physics Institute (PNPI, Gatchina). These measurements were performed at incident-pion momenta (700, 710, 720, and 730 MeV/c) in the vicinity of the threshold for the process under study by using the neutral-meson spectrometer designed and created at the Meson Physics Laboratory of PNPI. It is shown that, in the immediate vicinity of the threshold (685 MeV/c), the process of eta-meson production proceeds predominantly via S{sub 11}(1535)-resonance formation followed by the decay S{sub 11}(1535) {yields} {eta}n (the respective branching fraction is Br Almost-Equal-To 60%), but that, as the momentum of incident pions increases, the role of the D wave becomes ever more important. A detailed analysis of this effect indicates that it is due to the increasing contribution of the D{sub 13}(1520) resonance. Although the branching fraction of the decay of this resonance through the {eta}n channel is assumed to be very small (BR Almost-Equal-To 0.24%), the effect is enhanced owing to the interference between the D wave and the dominant resonance S{sub 11}(1535).
B. Julia-Diaz, H. Kamano, T.-S. H. Lee, A. Matsuyama, T. Sato, N. Suzuki
2009-04-01
Within the relativistic quantum field theory, we analyze the differences between the $\\pi N$ reaction models constructed from using (1) three-dimensional reductions of Bethe-Salpeter Equation, (2) method of unitary transformation, and (3) time-ordered perturbation theory. Their relations with the approach based on the dispersion relations of S-matrix theory are dicusssed.
Z. Bar-Yam; Amiran Tomaradze; A.A. Yershov; Alexander Ostrovidov; A.V. Popov; C. Olchanski; David Joffe; D.B. White; D.I. Ryabchikov; Doran Stienike; D.S. Brown; Dennis Weygand; E. King; Gary Adams; Hans Willutzki; I.A. Kachaev; I.N. Vardanian; J.A. Smith; James Bishop; John LoSecco; John P. Dowd; James Napolitano; Joachim Kuhn; Joseph Manak; John Cummings; K. Danyo; Kamal Seth; Ludmilla Sarycheva; M. Hayek; M.A. Kostin; Michael Witkowski; Mina Nozar; N. Shenhav; N.B. Sinev; Neal Cason; O.L. Kodolova; Paul Eugenio; R.W. Hackenburg; Sydney Taegar; Sergey Denisov; Suh-Urk Chung; Todd Adams; Todd Pedlar; V.A. Bodyagin; V.A. Dorofeev; V.L. Korotkikh; V.V. Lipaev; W. Kern; William Shephard; Xiao Shen; X.L. Fan
2001-04-01
An amplitude analysis of an exclusive sample of 5765 events from the reaction {pi}{sup -} p {yields} {eta}{prime}{pi}{sup -} p at 18 GeV/c is described. The {eta}{prime}{pi}{sup -} production is dominated by natural parity exchange and by three partial waves: those with J{sup PC} = 1{sup -+}, 2{sup ++}, and 4{sup ++}. A mass-dependent analysis of the partial-wave amplitudes indicates the production of the a{sub 2}(1320) meson as well as the a{sub 4}(2040) meson, observed for the first time decaying to {eta}{prime}{pi}{sup -}. The dominant, exotic (non-q{bar q}) 1{sup -+} partial wave is shown to be resonant with a mass of 1.597 {+-} 0.010{sub -0.010}{sup +0.045} GeV/c{sup 2} and a width of 0.340 {+-} 0.040 {+-} 0.050 GeV/c{sup 2}. This exotic state, the {pi}{sub 1}(1600), is produced with a t dependence which is different from that of the a{sub 2}(1320) meson, indicating differences between the production mechanisms for the two states.
NASA Astrophysics Data System (ADS)
Higashi, Yuko; Ikeno, Natumi; Nagahiro, Hideko; Hirenzaki, Satoru; Fujioka, Hiroyuki; Itahashi, Kenta; Tanaka, Yoshiki
2014-09-01
We study theoretically the 12C(p , d) reaction for the formation of the η' mesonic nucleus to optimize the experiments at GSI and FAIR, where the missing mass spectroscopy of the 12C(p , d) reaction is adopted to measure η' meson bound states in 11C. This method was proposed in Ref. and the peak structures are expected in the inclusive spectra of the deuteron in case that the discrete states exist. The semi-exclusive measurements are also considered at FAIR to reduce the background, where protons/charged pions are measured in coincidence with the deuteron. We present the theoretical distributions of the emitted charged particle in the (p , d) reaction. The charged particles produced by the η' absorption are expected to have uniform angular distribution with the specific energy of the absorption process, while those by the background distribute in the forward directions. Thus, we can reduce the background largely by the differences of the charged particle distributions from these processes. We use the microscopic transport model and we report the advantages of the semi-exclusive measurements.
Techniques in meson spectroscopy
Longacre, R.S.
1991-12-31
This report contains lectures on the following topics: the quark model and beyond using quantum chromodynamics; analysis of formation reactions; energy dependence of the partial wave amplitudes; where the data for the t-matrix analysis comes from; and coupled channel analysis of isoscalar mesons.
NASA Astrophysics Data System (ADS)
Hovdebo, Jordan L.; Kruczenski, Martín; Mateos, David; Myers, Robert C.; Winters, David J.
We study mesons in an {N} = 2 super Yang-Mills theory with fundamental matter from its dual string theory on AdS5 × S5 with a D7-brane probe. For quarks with a finite mass mq, the meson spectrum is discrete and exhibits a mass gap of order mq/√ {g2YM N}. The spectrum of mesons with large spin J is obtained from semiclassical rotating open strings attached to the D7-brane. It displays Regge behaviour for J << √ {g2YM N} whereas for J >> √ {g2YM N} it corresponds to that of two non-relativistic quarks bound by a Coulomb potential. We calculate
Physics opportunities with meson beams
Briscoe, William J.; Doring, Michael; Haberzettl, Helmut; Manley, D. Mark; Naruki, Megumi; Strakovsky, Igor I.; Swanson, Eric S.
2015-10-20
Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. Furthermore, the present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.
Formation of Slow Heavy Mesons in Nuclei
NASA Astrophysics Data System (ADS)
Hirenzaki, Satoru
2009-10-01
Meson - nucleus systems such as mesic atoms and mesic nuclei have been studied systematically for a long time. The binding energies and widths of these bound states provide us unique and valuable information on the meson-nucleus interactions. In addition, the measurements of light vector meson spectra in nucleus as the invariant mass of lepton pairs have also provided interesting information. So far, the properties of relatively light mesons have been studied well both theoretically and experimentally. In this contribution, to extend our studies to a domain of heavier mesons, we would like to report recent research activities on the formation of heavy mesons in nuclei with small momenta. We think it is very interesting to consider the in-medium properties of heavier mesons including heavy quark contents. As a first step to heavier mesons, we will report our studies on formation of slow phi meson in nuclei. In-medium properties of phi meson have been studied theoretically, which have close relation to K and K-bar meson properties in medium because of the strong coupling of phi to K and K-bar. The study of QCD sum rule and the data taken at KEK suggested 3 percent mass reduction of phi at the normal nuclear density, while the phi meson selfenergy calculated in some effective models indicated a significantly smaller attractive potential for phi. We will show the calculated spectra for some reactions.
Production of the {omega} meson in the pd{yields}{sup 3}He{omega} reaction at 1450 MeV and 1360 MeV
Schoenning, K.; Calen, H.; Fransson, K.; Gustafsson, L.; Hoeistad, B.; Jacewicz, M.; Johansson, T.; Keleta, S.; Kullander, S.; Kupsc, A.; Marciniewski, P.; Petren, H.; Ruber, R. J. M. Y.; Engblom, P. Thoerngren; Zlomanczuk, J.; Bargholtz, Chr.; Geren, L.; Lindberg, K.; Tegner, P.-E.; Zartova, I.
2009-04-15
The production of {omega} mesons in the pd{yields}{sup 3}He{omega} reaction has been studied at two energies near the kinematic threshold, T{sub p}=1450 MeV and T{sub p}=1360 MeV. The differential cross section was measured as a function of the {omega} c.m. angle at both energies over the whole angular range. Whereas the results at 1360 MeV are consistent with isotropy, strong rises are observed near both the forward and backward directions at 1450 MeV. Calculations made using a two-step model with an intermediate pion fail to reproduce the shapes of the measured angular distributions and also underestimate the total cross sections.
Evidence for a scalar meson resonance in the {pi}{sup -}p{yields}n{omega}{phi} reaction
Ivashin, A.; Ekimov, A.; Gouz, Yu.; Kachaev, I.; Karyukhin, A.; Konstantinov, V.; Makouski, M.; Matveev, V.; Myagkov, A.; Polyakov, B.; Ryabchikov, D.; Shalanda, N.; Soldatov, M.; Solodkov, A. A.; Solodkov, A. V.; Solovianov, O.; Sugonyaev, V.; Salomatin, Yu.; Volkov, E.; Khokhlov, Yu.
2010-08-05
The charge-exchange reaction {pi}{sup -}p{yields}n{omega}(780){phi}(1020) is studied with the VES setup. The ({omega}{phi}) system is observed at relatively low background. Its invariant mass distribution peaks near threshold. The two-particles partial wave analyses shows that the J{sup pc} = 0{sup ++} state dominates. This wave is compared with 0{sup ++} component in the ({omega}{omega}) system at the comparable mass, which was measured earlier.
Physics opportunities with meson beams
Briscoe, William J.; Doring, Michael; Haberzettl, Helmut; Manley, D. Mark; Naruki, Megumi; Strakovsky, Igor I.; Swanson, Eric S.
2015-10-20
Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledgemore » in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. Furthermore, the present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.« less
Korchin, A.Y.; Shebeko, A.V.
1984-01-01
The dependence of the cross section near the deuteron electrodisintegration threshold on the choice of the model for the NN interaction and for the form factors entering into the meson exchange current operator is studied. The results of the calculations are compared with new experimental data in a broad momentum-transfer range.
Meson-baryon interaction in the meson exchange picture
Doering, M.
2011-10-24
Elastic {pi}N scattering and the reaction {pi}{sup +}p{yields}K{sup +}{Sigma}{sup +} are described simultaneously in a unitary coupled-channels approach which respects analyticity. SU(3) flavor symmetry is used to relate the t- and u- channel exchanges that drive the meson-baryon interaction in the different channels. Angular distributions, polarizations, and spin-rotation parameters are compared with available experimental data. The pole structure of the amplitudes is extracted from the analytic continuation.
NASA Astrophysics Data System (ADS)
Battaglieri, Marco
The CLAS Collaboration is operating the CLAS detector at theThomas Jefferson National Laboratory (JLab) in USA. The unique combination of the detector large acceptance and high intensity of the continuous electron beam of CEBAF has opened the way to a comprehensive study of the hadrons structure in a kinematic domain between nuclear and particle physics. Meson spectroscopy plays a central role in the physics program of the Collaboration. Many exclusive channels have been studied with virtual and real photon beams in a wide kinematic domain providing key information about the hadron structure as well as the reactions dynamic. In this contribution, the rich physics program covered by present and future experiments will be reviewed.
Meson-meson interactions and Regge propagators
Beveren, Eef van Rupp, George
2009-08-15
By a reformulation of the loop expansion in the Resonance-Spectrum Expansion amplitude for meson-meson scattering, in terms of s-channel exchange of families of propagator modes, we obtain a formalism which allows for a wider range of applications. The connection with the unitarized amplitudes employed in some chiral theories is discussed. We also define an alternative for the Regge spectra and indicate how this may be observed in experiment.
Meson Photoproduction Experiments with CLAS
Eugene Pasyuk
2012-12-01
A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to light baryon spectroscopy. Meson photoprodcution experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams and frozen spin polarized targets provide unique conditions for this type of experiments. This combination of experimental tools gives a remarkable opportunity to measure double polarization observables for different pseudo-scalar meson photoproduction processes. For the first time, a complete or nearly complete measurement became possible and will facilitate model independent extraction of the reaction amplitude. An overview of the experimental program and its current status together with recent results on double polarization measurements in π{sup +} photoproduction are presented.
The Meson Spectroscopy Program at the Jefferson Laboratory
Filippi, Alessandro
2015-06-01
The experimental techniques that will be applied by the next generation meson spectroscopy experiments at JLab are described. For the first time, these experiments will be able to exploit the features of a photon beam of unprecedented intensity and momentum resolution, that will allow to perform precision studies of meson states with masses below 3 GeV/c^{2}. Photon induced reactions will enhance the production of spin-1 mesons, that are of particular interest according to the most recent Lattice QCD calculations of the lightest exotic hybrid meson.
Shklyar, V.; Lenske, H.; Mosel, U.; Penner, G.
2005-05-01
The pion- and photon-induced reactions for the final states {gamma}N,{pi}N,2{pi}N,{eta}N, and {omega}N are studied within a coupled-channel effective Lagrangian approach in the energy region from the pion threshold up to 2 GeV. To investigate the role of the nucleon resonances in the different reactions we include all known states with spin -1/2, -3/2, and -5/2 and masses below 2 GeV. We find a strong contribution from the D{sub 15}(1675) resonance to the {pi}N{yields}{omega}N reaction. While the F{sub 15}(1680) state only slightly influences the {omega} meson production in the {pi}N scattering its role is enhanced in the {omega} photoproduction due to the large electromagnetic coupling of this resonance. We predict the beam asymmetry {sigma}{sub X} to be a negative in the {gamma}p{yields}{omega}p reaction near to the threshold. Above the 1.85 GeV the asymmetry is found to change its sign and becomes positive at forward directions. The presented findings can be experimentally tested at GRAAL, CLAS, and CB-ELSA facilities.
Charged {rho}-meson production in neutrino-induced reactions at
Agababyan, N. M.; Ammosov, V. V.; Grigoryan, N.; Gulkanyan, H.; Ivanilov, A. A.; Karamyan, Zh.; Korotkov, V. A.
2011-02-15
The production of charged {rho} mesons on nuclei and nucleons is investigated in charged current neutrino interactions at moderate energies (
Monte Carlo Nucleon Meson Transport Code System.
Energy Science and Technology Software Center (ESTSC)
2000-11-17
Version 00 NMTC/JAERI97 is an upgraded version of the code system NMTC/JAERI, which was developed in 1982 at JAERI and is based on the CCC-161/NMTC code system. NMTC/JAERI97 simulates high energy nuclear reactions and nucleon-meson transport processes.
Barnes, T.
2001-04-26
This short contribution is a lite MESON2000 conference summary. As appropriate for the 600th anniversary of the Jagellonian University, it begins with a brief summary of the last 600 years of European history and its place in hadron physics. Next a ''physicist chirality'' order parameter PC is introduced. When applied to MESON2000 plenary speakers this order parameter illustrates the separation of hadron physicists into disjoint communities. The individual plenary talks in MESON2000 are next sorted according to the subconference associated with each of the 36 plenary speakers. Finally, I conclude with a previously unreported Feynman story regarding the use of models in hadron physics.
Semay, Claude; Buisseret, Fabien; Silvestre-Brac, Bernard
2009-05-01
A hybrid meson is a quark-antiquark pair in which, contrary to ordinary mesons, the gluon field is in an excited state. In the framework of constituent models, the interaction potential is assumed to be the energy of an excited string. An approximate, but accurate, analytical solution of the Schroedinger equation with such a potential is presented. When applied to hybrid charmonia and bottomonia, towers of states are predicted in which the masses are a linear function of a harmonic oscillator band number for the quark-antiquark pair. Such a formula could be a reliable guide for the experimental detection of heavy hybrid mesons.
Low-energy {omega} ({yields}{pi}{sup 0}{gamma}) meson photoproduction in the nucleus
Das, Swapan
2011-06-15
The {pi}{sup 0{gamma}} invariant mass distribution spectra in the ({gamma},{pi}{sup 0{gamma}}) reaction were measured by the TAPS/ELSA Collaboration to look for the hadron parameters of the {omega} meson in the Nb nucleus. We study the mechanism for this reaction, where we consider that the elementary reaction in the Nb nucleus proceeds as {gamma}N{yields}{omega}N;{omega}{yields}{pi}{sup 0}{gamma}. The {omega}-meson photoproduction amplitude for this reaction is extracted from the measured four-momentum transfer distribution in the {gamma}p{yields}{omega}p reaction. The propagation of the {omega} meson and the distorted wave function for the {pi}{sup 0} meson in the final state are described by the eikonal form. The {omega} and {pi}{sup 0} mesons' nucleus optical potentials, appearing in the {omega} meson propagator and {pi}{sup 0} meson distorted wave function respectively, are estimated using the t{rho} approximation. The effects of pair correlation and color transparency are also studied. The calculated results do not show medium modification for the {omega} meson produced in the nucleus for momentum greater than 200 MeV. It occurs because the {omega} meson predominantly decays outside the nucleus. The dependence of the cross section on the final-state interaction is also investigated. The broadening of the {omega}-meson mass distribution spectra is shown to occur due to the large resolution width associated with the detector used in the experiment.
Observation of the {chi}{sub c2}(2P) meson in the reaction {gamma}{gamma}{yields}DD at BABAR
Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D. N.; Hooberman, B.; Kerth, L. T.; Kolomensky, Yu. G.
2010-05-01
A search for the Z(3930) resonance in {gamma}{gamma} production of the DD system has been performed using a data sample corresponding to an integrated luminosity of 384 fb{sup -1} recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The DD invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8{sigma}. We determine mass and width values of (3926.7{+-}2.7{+-}1.1) MeV/c{sup 2} and (21.3{+-}6.8{+-}3.6) MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C parity (J{sup PC}=2{sup ++}); therefore we identify the Z(3930) state as the {chi}{sub c2}(2P) meson. The value of the partial width {Gamma}{sub {gamma}{gamma}x}B(Z(3930){yields}DD) is found to be (0.24{+-}0.05{+-}0.04) keV.
Observation of the chi_c2(2P) meson in the reaction gamma gamma -> D Dbar at BaBar
Aubert, B.; Karyotakis, Y.; Lees, J.P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D.N.; Hooberman, B.; Kerth, L.T.; Kolomensky, Yu.G.; Lynch, G. /UC, Berkeley /Birmingham U. /Ruhr U., Bochum /British Columbia U. /Brunel U. /Novosibirsk, IYF /UC, Irvine /UC, Riverside /UC, San Diego /UC, Santa Barbara /UC, Santa Cruz /Caltech /Cincinnati U. /Colorado U. /Colorado State U. /Dortmund U. /Dresden, Tech. U. /Ecole Polytechnique /Edinburgh U. /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /INFN, Ferrara /INFN, Ferrara /Ferrara U. /Frascati /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /INFN, Genoa /INFN, Genoa /Genoa U. /Harvard U. /Heidelberg U. /Humboldt U., Berlin /Imperial Coll., London /Iowa State U. /Iowa State U. /Johns Hopkins U. /Paris U., VI-VII /LLNL, Livermore /Liverpool U. /Queen Mary, U. of London /Royal Holloway, U. of London /Louisville U. /Mainz U., Inst. Kernphys. /Manchester U. /Maryland U. /Massachusetts U., Amherst /MIT /McGill U. /INFN, Milan /Milan U. /INFN, Milan /INFN, Milan /Milan U. /Mississippi U. /Montreal U. /Mt. Holyoke Coll. /INFN, Naples /Naples U. /INFN, Naples /INFN, Naples /Naples U. /NIKHEF, Amsterdam /NIKHEF, Amsterdam /Notre Dame U. /Ohio State U. /Oregon U. /INFN, Padua /Padua U. /INFN, Padua /INFN, Padua /Padua U. /Paris U., VI-VII /Pennsylvania U. /INFN, Perugia /Perugia U. /INFN, Pisa /Pisa U. /INFN, Pisa /Pisa, Scuola Normale Superiore /INFN, Pisa /Pisa U. /INFN, Pisa /Princeton U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /INFN, Rome /Rome U. /INFN, Rome /Rostock U. /Rutherford /DAPNIA, Saclay /SLAC /South Carolina U. /Stanford U., Phys. Dept. /SUNY, Albany /Tel Aviv U. /Tennessee U. /Texas Nuclear Corp., Austin /Texas U., Dallas /INFN, Turin /Turin U. /INFN, Trieste /Trieste U. /Valencia U. /Victoria U. /Warwick U. /Wisconsin U., Madison
2010-05-26
A search for the Z(3930) resonance in {gamma}{gamma} production of the D{bar D} system has been performed using a data sample corresponding to an integrated luminosity of 384 fb{sup -1} recorded by the BABAR experiment at the PEP-II asymmetric-energy electron-positron collider. The D{bar D} invariant mass distribution shows clear evidence of the Z(3930) state with a significance of 5.8{sigma}. We determine mass and width values of (3926.7 {+-} 2.7 {+-} 1.1)MeV/c{sup 2} and (21.3 {+-} 6.8 {+-} 3.6)MeV, respectively. A decay angular analysis provides evidence that the Z(3930) is a tensor state with positive parity and C-parity (J{sup PC} = 2{sup ++}); therefore we identify the Z(3930) state as the {chi}{sub c2}(2P) meson. The value of the partial width {Lambda}{sub {gamma}{gamma}} x {Beta}(Z(3930) {yields} D{bar D}) is found to be (0.24 {+-} 0.05 {+-} 0.04) keV.
ρ meson decays of heavy hybrid mesons
NASA Astrophysics Data System (ADS)
Zhang, Liang; Huang, Peng-Zhi
2016-07-01
We calculate the ρ meson couplings between the heavy hybrid doublets Hh/Sh/Mh/Th and the ordinary qQ̅ doublets in the framework of the light-cone QCD sum rule. The sum rules obtained rely mildly on the Borel parameters in their working regions. The resulting coupling constants are rather small in most cases. Supported by National Natural Science Foundation of China (11105007)
Absorption of the omega and phi mesons in nuclei
Chaden Djalali, Michael H. Wood, Michael Paolone, Rakhsha Nasseripour, Dennis P. Weygand
2012-04-01
The properties of hadrons, such as their masses and widths, are predicted to be modified in dense and/or hot nuclear matter. Particular attention has been given to the modifications of vector-meson properties in ordinary nuclear matter where chiral symmetry is predicted to be partially restored due to a change in the quark condensate. Different models predict relatively large measurable changes in the mass and/or the width of these mesons. The e{sup +}e{sup -} decay channel of these mesons has negligible final-state interactions (FSI), providing an ideal tool to study their possible in-medium modifications Due to its short lifetime, the {rho} meson has a substantial probability of decaying in the nucleus and its study has been previously reported. Due to their long lifetimes, the {omega} and {phi} mesons are ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. These mesons have been photo-produced in several targets ranging from deuterium to lead. Nuclear transparencies ratios have been derived for different decay channels. These ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the {omega} meson is stronger than that reported by the CBELSATAPS experiment. These results are compared to recent theoretical models.
Meson Spectroscopy in the Light Quark Sector
de Vita, Raffaella
2014-04-01
Understanding the hadron spectrum is one of the fundamental issues in modern particle physics. We know that existing hadron configurations include baryons, made of three quarks, and mesons, made of quark-antiquark pairs. However most of the mass of the hadrons is not due to the mass of these elementary constituents but to their binding force. Studying the hadron spectrum is therefore a tool to understand one of the fundamental forces in nature, the strong force, and Quantum Chromo Dynamics (QCD), the theory that describes it. This investigation can provide an answer to fundamental questions as what is the origin of the mass of hadrons, what is the origin of quark confinement, what are the relevant degrees of freedom to describe these complex systems and how the transition between the elementary constituents, quarks and gluons, and baryons and mesons occurs. In this field a key tool is given by meson spectroscopy. Mesons, being made by a quark and an anti-quark, are the simplest quark bound system and therefore the ideal benchmark to study the interaction between quarks and understand what the role of gluons is. In this investigation, it is fundamental to precisely determine the spectrum and properties of mesons but also to search for possible unconventional states beyond the configuration q{anti q} as tetraquarks (qq{anti qq}), hybrids (q{anti q}g) and glueballs. These states can be distinguished unambiguously from regular mesons when they have exotic quantum numbers, i.e. combinations of total angular momentum, spin and parity that are not allowed for q{anti q} states. These are called exotic quantum numbers and the corresponding states are referred to as exotics. The study of the meson spectrum and the search for exotics is among the goals of several experiments in the world that exploit different reaction processes, as e{sup +}e{sup −} annihilation, p{anti p} annihilation, pion scattering, proton-proton scattering and photo-production, to produce meson states
Coherent ω-Meson Photoproduction off Deuteron
NASA Astrophysics Data System (ADS)
Chetry, Taya; Hicks, Kenneth; CLAS Collaboration
2016-03-01
Coherent ω photoproduction from the deuteron has been studied using CLAS at Jefferson Lab, Virginia, as a function of the photon energy and the 4-momentum transfer. Tagged photons with beam energies between 0.8 and 3.6 GeV were produced using the bremsstrahlung process incident on a deuterium target, during the run period g10. The final state particles detected are an energetic deuteron and a pair of charged pions. These events were constrained to have neutral pion missing mass, to ensure an exclusive reaction where an ω-meson decays into a π+, a π- and a π0. This study allows to test models of hadronic scattering of ω-mesons from the nucleon, as it is not possible to produce beams of ω-mesons. A preliminary differential cross section of the ω-meson in the coherent process is presented. In addition, this final state is useful to investigate a possible d* dibaryon resonance that has been seen in other reaction channels at CLAS, as well as being seen earlier in partial-wave analysis of pion-deuteron scattering at a mass of about 2145 MeV.
Absorption of the omega and phi Mesons in Nuclei
M. H. Wood, R. Nasseripour, M. Paolone, C. Djalali, D. P. Weygand, the CLAS Collaboration
2010-09-01
Due to their long lifetimes, the $\\omega$ and $\\phi$ mesons are the ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. During the E01-112 experiment at the Thomas Jefferson National Accelerator Facility, the mesons were photoproduced from $^{2}$H, C, Ti, Fe, and Pb targets. This paper reports the first measurement of the ratio of nuclear transparencies for the $e^{+}e^{-}$ channel. The ratios indicate larger in-medium widths compared with what have been reported in other reaction channels.
Liu Yunhu; Shao Jianxin; Wang Xiaogang; Zhang Ziying; Li Demin
2008-02-01
Based on the main assumption that the D{sub sJ}(2860) belongs to the 2{sup 3}P{sub 0} qq multiplet, the masses of the scalar meson nonet are estimated in the framework of the relativistic independent quark model, Regge phenomenology, and meson-meson mixing. We suggest that the a{sub 0}(1005), K{sub 0}*(1062), f{sub 0}(1103), and f{sub 0}(564) constitute the ground scalar meson nonet; it is supposed that these states would likely correspond to the observed states a{sub 0}(980), {kappa}(900), f{sub 0}(980), and f{sub 0}(600)/{sigma}, respectively. Also a{sub 0}(1516), K{sub 0}*(1669), f{sub 0}(1788), and f{sub 0}(1284) constitute the first radial scalar meson nonet, it is supposed that these states would likely correspond to the observed states a{sub 0}(1450), K{sub 0}*(1430), f{sub 0}(1710), and f{sub 0}(1370), respectively. The scalar state f{sub 0}(1500) may be a good candidate for the ground scalar glueball. The agreement between the present findings and those given by other different approaches is satisfactory.
Nuclear photoproduction of vector mesons within a Monte Carlo approach
NASA Astrophysics Data System (ADS)
González, I.; Guzmán, F.; Deppman, A.
2014-05-01
We present recent improvements in the crisp code for nuclear reaction simulation. The photoproduction of vector mesons was included in the code, which can evaluate also final state interaction of these mesons with the nucleus. Effects such as shadowing, subthreshold production, and Pauli blocking can be observed. The model is described in detail and some important quantities, such as cross section and nuclear transparency, are calculated as examples of the potential of our code.
B Decays Involving Light Mesons
Eschrich, Ivo Gough; /UC, Irvine
2007-01-09
Recent BABAR results for decays of B-mesons to combinations of non-charm mesons are presented. This includes B decays to two vector mesons, B {yields} {eta}{prime}({pi}, K, {rho}) modes, and a comprehensive Dalitz Plot analysis of B {yields} KKK decays.
Frederic D. R. Bonnet; Robert G. Edwards; George T. Fleming; Randal Lewis; David Richards
2003-07-22
We have started a program to compute the electromagnetic form factors of mesons. We discuss the techniques used to compute the pion form factor and present preliminary results computed with domain wall valence fermions on MILC asqtad lattices, as well as Wilson fermions on quenched lattices. These methods can easily be extended to rho-to-gamma-pi transition form factors.
Absorption of the {omega} and {phi} Mesons in Nuclei
Wood, M. H.; Nasseripour, R.; Berman, B. L.; Briscoe, W. J.; Munevar, E.; Strakovsky, I. I.; Paolone, M.; Djalali, C.; Gothe, R. W.; Graham, L.; Tedeschi, D. J.; Tkachenko, S.; Zhao, Z. W.; Weygand, D. P.; Batourine, V.; Burkert, V. D.; Carman, D. S.; Deur, A.; Guo, L.; Nadel-Turonski, P.
2010-09-10
Because of their long lifetimes, the {omega} and {phi} mesons are the ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. During the E01-112 experiment at the Thomas Jefferson National Accelerator Facility, the mesons were photoproduced from {sup 2}H, C, Ti, Fe, and Pb targets. This Letter reports the first measurement of the ratio of nuclear transparencies for the e{sup +}e{sup -} channel. The ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the {omega} meson is stronger than that reported by the CBELSA-TAPS experiment and cannot be explained by recent theoretical models.
B meson decays into charmless pseudoscalar scalar mesons
Delepine, D.; Lucio M, J. L.; Ramirez, Carlos A.; Mendoza S, J. A.
2007-06-19
The nonleptonic weak decays of meson B into a scalar and pseudoscalar meson are studied. The scalar mesons under consideration are {sigma} (or f0(600)), f0(980), a0(980) and K{sub 0}{sup *}(1430). We calculate the Branching ratios in the Naive Factorization approximation. Scalars are assumed to be qq-bar bounded sates, but an estimation can be obtained in the case they are four bounded states.
Bianco, Stefano
2006-02-11
The scenario of heavy quark meson spectroscopy underwent recently a major revolution, after the observation of BABAR and CLEO, confirmed by BELLE, of DsJ L=1 excited states, and by further evidences by SELEX. These experimental results have cast doubts on the incarnations of the ideas of Heavy Quark Effective Theory in heavy quark spectroscopy. I shall review the status of experimental data, discuss implications and sketch an outlook.
Production of polarized vector mesons off nuclei
Kopeliovich, B. Z.; Nemchik, J.; Schmidt, Ivan
2007-08-15
Using the light-cone QCD dipole formalism we investigate manifestations of color transparency (CT) and coherence length (CL) effects in electroproduction of longitudinally (L) and transversally (T) polarized vector mesons. Motivated by forthcoming data from the HERMES experiment we predict both the A and Q{sup 2} dependence of the L/T ratios for {rho}{sup 0} mesons produced coherently and incoherently off nuclei. For an incoherent reaction the CT and CL effects add up and result in a monotonic A dependence of the L/T ratio at different values of Q{sup 2}. In contrast, for a coherent process the contraction of the CL with Q{sup 2} causes an effect opposite to that of CT and we expect quite a nontrivial A dependence.
Electroproduction of tensor mesons in QCD
NASA Astrophysics Data System (ADS)
Braun, V. M.; Kivel, N.; Strohmaier, M.; Vladimirov, A. A.
2016-06-01
Due to multiple possible polarizations hard exclusive production of tensor mesons by virtual photons or in heavy meson decays offers interesting possibilities to study the helicity structure of the underlying short-distance process. Motivated by the first measurement of the transition form factor γ∗γ → f 2(1270) at large momentum transfers by the BELLE collaboration we present an improved QCD analysis of this reaction in the framework of collinear factorization including contributions of twist-three quark-antiquark-gluon operators and an estimate of soft end-point corrections using light-cone sum rules. The results appear to be in good agreement with the data, in particular the predicted scaling behavior is reproduced in all cases.
Rare B Meson Decays With Omega Mesons
Zhang, Lei; /Colorado U.
2006-04-24
Rare charmless hadronic B decays are particularly interesting because of their importance in understanding the CP violation, which is essential to explain the matter-antimatter asymmetry in our universe, and of their roles in testing the ''effective'' theory of B physics. The study has been done with the BABAR experiment, which is mainly designed for the study of CP violation in the decays of neutral B mesons, and secondarily for rare processes that become accessible with the high luminosity of the PEP-II B Factory. In a sample of 89 million produced B{bar B} pairs on the BABAR experiment, we observed the decays B{sup 0} {yields} {omega}K{sup 0} and B{sup +} {yields} {omega}{rho}{sup +} for the first time, made more precise measurements for B{sup +} {yields} {omega}h{sup +} and reported tighter upper limits for B {yields} {omega}K* and B{sup 0} {yields} {omega}{rho}{sup 0}.
Coupling vector and pseudoscalar mesons to study baryon resonances
Khemchandani, K. P.; Kaneko, H.; Hosaka, A.; Martinez Torres, A.; Nagahiro, H.
2011-11-01
A study of meson-baryon systems with total strangeness -1 is made within a framework based on the chiral and hidden local symmetries. These systems consist of octet baryons, pseudoscalar and vector mesons. The pseudoscalar meson-baryon (PB) dynamics has been earlier found determinant for the existence of some strangeness -1 resonances, for example, {Lambda}(1405), {Lambda}(1670), etc. The motivation of the present work is to study the effect of coupling the closed vector meson-baryon (VB) channels to these resonances. To do this, we obtain the PB{yields}PB and VB{yields}VB amplitudes from the t-channel diagrams and the PB{r_reversible}VB amplitudes are calculated using the Kroll-Ruddermann term where, considering the vector meson dominance phenomena, the photon is replaced by a vector meson. The calculations done within this formalism reveal a very strong coupling of the VB channels to the {Lambda}(1405) and {Lambda}(1670). In the isospin 1 case, we find evidence for a double pole structure of the {Sigma}(1480) which, like the isospin 0 resonances, is also found to couple strongly to the VB channels. The strong coupling of these low-lying resonances to the VB channels can have important implications on certain reactions producing them.
Cross sections for inelastic meson-meson scattering via quark-antiquark annihilation
NASA Astrophysics Data System (ADS)
Shen, Zhen-Yu; Xu, Xiao-Ming; Weber, H. J.
2016-08-01
We study inelastic meson-meson scattering that is governed by quark-antiquark annihilation and creation involving a quark and an antiquark annihilating into a gluon, and subsequently the gluon creating another quark-antiquark pair. The resultant hadronic reactions include for I =1 : π π →ρ ρ , K K ¯→K*K¯*, K K¯*→K*K¯*, K*K ¯→K*K¯*, as well as π π →K K ¯, π ρ →K K¯*, π ρ →K*K ¯, and K K ¯→ρ ρ . In each reaction, one or two Feynman diagrams are involved in the Born approximation. We derive formulas for the unpolarized cross section, the transition amplitude, and the transition potential for quark-antiquark annihilation and creation. The unpolarized cross sections for the reactions are calculated at six temperatures, and prominent temperature dependence is found. It is due to differences among mesonic temperature dependence in hadronic matter.
The light meson spectroscopy program
Smith, Elton S.
2014-06-01
Recent discoveries of a number of unexpected new charmomium-like meson states at the BaBar and Belle B-factories have demonstrated how little is still known about meson spectroscopy. In this talk we will review recent highlights of the light quark spectroscopy from collider and fixed target experiments.
Exotic meson spectroscopy with CLAS
Adams, G.; Napolitano, J.
1994-04-01
The identification and study of mesons with explicit gluonic degrees of freedom will provide major constraints on nonperturbative QCD and models thereof. CLAS will provide a unique opportunity for studying these resonances by measuring photoproduction of multi-meson final states.
Crowe, K.M.
1992-01-01
The activities of this group are primarily concerned with experiments using the Crystal Barrel Detector. This detector is installed and operating at the Low Energy Antiproton Ring (LEAR) at CERN. QCD, the modem theory of the strong interaction, is reasonably well understood at high energies, but unfortunately, low-energy QCD is still not well understood, and is far from being adequately tested. The Crystal Barrel experiments are designed to provide some of the tests. The basic line of research involves meson spectroscopy, analyses bearing on the quark and/or gluon content of nuclear states, and the exploration of mechanisms and rules which govern p[bar p] annihilation dynamics. The Crystal Barrel Detector detects and identifies charged and neutral particles with a geometric acceptance close to 100%. The principal component of the detector is an array of 1,380 CsI(TI) crystals. These crystals surround a Jet Drift Chamber (JDC), located in a 1.5 Tesla magnetic field, which measures the momentum and dE/dx of charged particles. One of the very interesting physics goals of the detector is a search for exotic mesonic states -- glueballs and hybrids. Annihilation at rest will be studied with both liquid and gaseous hydrogen targets. The gaseous target offers the possibility of triggering on atomic L-shell X rays so that specific initial angular momentum states can be studied.These topics as well as other related topics are discussed in this report.
Crowe, K.M.
1992-12-01
The activities of this group are primarily concerned with experiments using the Crystal Barrel Detector. This detector is installed and operating at the Low Energy Antiproton Ring (LEAR) at CERN. QCD, the modem theory of the strong interaction, is reasonably well understood at high energies, but unfortunately, low-energy QCD is still not well understood, and is far from being adequately tested. The Crystal Barrel experiments are designed to provide some of the tests. The basic line of research involves meson spectroscopy, analyses bearing on the quark and/or gluon content of nuclear states, and the exploration of mechanisms and rules which govern p{bar p} annihilation dynamics. The Crystal Barrel Detector detects and identifies charged and neutral particles with a geometric acceptance close to 100%. The principal component of the detector is an array of 1,380 CsI(TI) crystals. These crystals surround a Jet Drift Chamber (JDC), located in a 1.5 Tesla magnetic field, which measures the momentum and dE/dx of charged particles. One of the very interesting physics goals of the detector is a search for exotic mesonic states -- glueballs and hybrids. Annihilation at rest will be studied with both liquid and gaseous hydrogen targets. The gaseous target offers the possibility of triggering on atomic L-shell X rays so that specific initial angular momentum states can be studied.These topics as well as other related topics are discussed in this report.
Status of Meson Photoproduction Experiments with CLAS
Pasyuk, Eugene A.
2014-01-01
A large part of the experimental program in Hall B of the Jefferson Lab is dedicated to baryon spectroscopy. Meson photoproduction experiments are essential part of this program. CEBAF Large Acceptance Spectrometer (CLAS) and availability of circularly and linearly polarized tagged photon beams in combination with longitudinally and transversely polarized frozen spin targets provide unique conditions for this type of experiments. For the first time, a complete or nearly complete measurement became possible and will allow model independent extraction of the reaction amplitude. The measurements were complete with both proton and deuteron targets. An overview of the collected experimental data will be presented.
Photoproduction of scalar mesons at CLAS
NASA Astrophysics Data System (ADS)
Chandavar, Shloka; Hicks, Kenneth; Weygand, Dennis; CLAS Collaboration
2013-10-01
A single gluon, which carries color charge, cannot exist independently outside a hadron. Lattice QCD calculations in pure SU(3), however, predict the existence of glueballs which are bound states of two or more gluons. In the real world, the challenge to identify glueballs experimentally is the fact they mix with meson states. The f0 (1500) is one of several candidates for the lightest glueball, with JPC =0++ . We investigate the presence of this particle in photoproduction by analyzing the reaction γp -->fJ p -->KS0KS0 p --> 2 (π+π-) p . This reaction was studied using data from the g12 experiment performed using the CLAS detector at Jefferson Lab. A preliminary partial wave analysis, performed on the KS0KS0 invariant mass spectrum, will be presented. These results update those presented for this reaction channel at previous conferences. This work is supported by grant from NSF.
Electromagnetic production of vector mesons at low energies
Oh, Y.; Titov, A. I.; Lee, T.-S. H.
2000-05-17
The authors have investigated exclusive photoproduction of light vector mesons ({omega}, {rho} and {phi}) on the nucleon at low energies. In order to explore the questions concerning the so-called missing nucleon resonances, they first establish the predictions from a model based on the Pomeron and meson exchange mechanisms. They have also explored the contributions due to the mechanisms involving s- and u-channel intermediate nucleon state. Some discrepancies found at the energies near threshold and large scattering angles suggest a possibility of using this reaction to identify the nucleon resonances.
PSEUDOVECTOR MESONS, HYBRIDS AND GLUEBALLS
L. BURAKOVSKY; P. PAGE
2000-06-01
The authors consider glueball-(hybrid) meson mixing for the low-lying four pseudovector states. The h{sub 1}{prime}(1380) decays dominantly to K*K with some presence in {rho}{pi} and {omega}{eta}. The newly observed h{sub 1}(1600) has a D- to S-wave width ratio to {omega}{eta} which makes its interpretation as a conventional meson unlikely. They predict the decay pattern of the isopartner conventional or hybrid meson b{sub 1}(1650). A notably narrow s{bar s} partner h{sub 1}{prime}(1810) is predicted.
Rescattering in meson photoproduction from few body systems
J-M. Laget
2006-04-01
Exclusive reactions induced at high momentum transfer in few body systems provide us with an original way to study the production and propagation of hadrons in cold nuclear matter. In very well-defined parts of the phase space, the reaction amplitude develops a logarithmic singularity. It is on solid ground since it depends on only on-shell elementary amplitudes and on low momentum components of the nuclear wave function. This is the best window for studying the propagation of exotic configurations of hadrons such as the onset of color transparency. It may appear earlier in meson-photoproduction reactions, more particularly in the strange sector, than in the more classical quasi-elastic scattering of electrons. More generally, those reactions provide us with the best tool to determine the cross section of the scattering of various hadrons (strange particles, vector mesons) from the nucleon and to obtain the production of possible exotic states.
Photoproduction of Mesons on Quasi-Free Nucleons
NASA Astrophysics Data System (ADS)
Keshelashvili, I.
2014-11-01
The investigation of excited baryon states is important to understand the underling nature/symmetries of hadronic matter. Historically, the first nucleon excitation experiments have been done using charged pion and kaon secondary beams. Later the antiproton-proton scattering has also been involved. However, since the beginning of the 90's meson photoproduction reactions have been considered as a powerful tool in baryon spectroscopy. In this contribution, we overview our experimental programs conducted at the bremsstrahlung photon beams of the MAMI accelerator in Mainz and the ELSA accelerator in Bonn. The results are differential and total cross sections for photoproduction of light neutral mesons and of meson pairs off quasi-free nucleons bound in the deuteron (and sometimes other light nuclei). The scientific programs of this experiments also include single and double polarization measurements as well.
Observation of in-medium modifications of the omega meson.
Trnka, D; Anton, G; Bacelar, J C S; Bartholomy, O; Bayadilov, D; Beloglazov, Y A; Bogendörfer, R; Castelijns, R; Crede, V; Dutz, H; Ehmanns, A; Elsner, D; Ewald, R; Fabry, I; Fuchs, M; Essig, K; Funke, Ch; Gothe, R; Gregor, R; Gridnev, A B; Gutz, E; Höffgen, S; Hoffmeister, P; Horn, I; Hössl, J; Jaegle, I; Junkersfeld, J; Kalinowsky, H; Klein, Frank; Klein, Fritz; Klempt, E; Konrad, M; Kopf, B; Kotulla, M; Krusche, B; Langheinrich, J; Löhner, H; Lopatin, I V; Lotz, J; Lugert, S; Menze, D; Messchendorp, J G; Mertens, T; Metag, V; Morales, C; Nanova, M; Novotny, R; Ostrick, M; Pant, L M; van Pee, H; Pfeiffer, M; Roy, A; Radkov, A; Schadmand, S; Schmidt, Ch; Schmieden, H; Schoch, B; Shende, S; Suft, G; Sumachev, V V; Szczepanek, T; Süle, A; Thoma, U; Varma, R; Walther, D; Weinheimer, Ch; Wendel, Ch
2005-05-20
The photoproduction of omega mesons on nuclei has been investigated using the Crystal Barrel/TAPS experiment at the ELSA tagged photon facility in Bonn. The aim is to study possible in-medium modifications of the omega meson via the reaction gamma + A --> omega + X --> pi(0)gamma + X('). Results obtained for Nb are compared to a reference measurement on a LH2 target. While for recoiling, long-lived mesons (pi(0), eta, and eta;(')), which decay outside of the nucleus, a difference in the line shape for the two data samples is not observed, we find a significant enhancement towards lower masses for omega mesons produced on the Nb target. For momenta less than 500 MeV/c an in-medium omega meson mass of M(medium) = [722(+4)(-4)(stat)+35-5(syst)] MeV/c(2) has been deduced at an estimated average nuclear density of 0.6rho(0). PMID:16090166
NASA Astrophysics Data System (ADS)
Pennington, M. R.
1989-04-01
The search for I=0 0++ mesons is described. We highlight the crucial role played by the states in the 1 GeV region. An analysis program that with unimpeachable data would produce definitive results on these is outlined and shown with present data to provide prima facie evidence for dynamics beyond that of the quark model. We briefly speculate on the current status of the lowest mass scalar mesons and discuss how experiment can resolve the unanswered issues.
Strange meson production in Al+Al collisions at 1.9 A GeV
NASA Astrophysics Data System (ADS)
Gasik, P.; Piasecki, K.; Herrmann, N.; Leifels, Y.; Matulewicz, T.; Andronic, A.; Averbeck, R.; Barret, V.; Basrak, Z.; Bastid, N.; Benabderrahmane, M. L.; Berger, M.; Buehler, P.; Cargnelli, M.; Čaplar, R.; Crochet, P.; Czerwiakowa, O.; Deppner, I.; Dupieux, P.; Dželalija, M.; Fabbietti, L.; Fodor, Z.; Gašparić, I.; Grishkin, Y.; Hartmann, O. N.; Hildenbrand, K. D.; Hong, B.; Kang, T. I.; Kecskemeti, J.; Kim, Y. J.; Kirejczyk, M.; Kiš, M.; Koczon, P.; Kotte, R.; Lebedev, A.; Le Fèvre, A.; Liu, J. L.; Lopez, X.; Manko, V.; Marton, J.; Münzer, R.; Petrovici, M.; Rami, F.; Reischl, A.; Reisdorf, W.; Ryu, M. S.; Schmidt, P.; Schüttauf, A.; Seres, Z.; Sikora, B.; Sim, K. S.; Simion, V.; Siwek-Wilczyńska, K.; Smolyankin, V.; Suzuki, K.; Tymiński, Z.; Wagner, P.; Weber, I.; Widmann, E.; Wiśniewski, K.; Xiao, Z. G.; Yushmanov, I.; Zhang, Y.; Zhilin, A.; Zinyuk, V.; Zmeskal, J.
2016-06-01
The production of K+, K- and φ (1020) mesons is studied in Al+Al collisions at a beam energy of 1.9A GeV which is close to or below the production threshold in NN reactions. Inverse slopes, anisotropy parameters, and total emission yields of K± mesons are obtained. A comparison of the ratio of kinetic energy distributions of K- and K+ mesons to the HSD transport model calculations suggests that the inclusion of the in-medium modifications of kaon properties is necessary to reproduce the ratio. The inverse slope and total yield of φ mesons are deduced. The contribution to K- production from φ meson decays is found to be [17 ± 3(stat)^{+2}_{-7}(syst)]%. The results are in line with the previous K± and φ data obtained for different colliding systems at similar incident beam energies.
D meson decay channels that involve light scalar mesons
NASA Astrophysics Data System (ADS)
Fariborz, Amir
2013-04-01
A generalized linear sigma model of low-energy QCD is used to study several decay channels of D mesons that involve light scalar meson as a decay product. Such studies require reliable models for scalar mesons that take into account underlying mixing among quark-antiquarks, tetra quarks and glueballs. In this talk, the generalized linear sigma model of low-energy QCD for understanding the properties of scalar mosons will be briefly presented, and he application of this model to studies of heavier meson decays [such as the semileptonic decay Ds(1968)->f0(980) e^+ ν] will be presented, and a few directions for further extensions of the model will be outlined. Refs. A.H. Fariborz, R. Jora, J. Schechter and M.N. Shahid, ``Semi-leptonic Ds^+(1968) Decays as a Scalar Meson Probe,'' Physical Review D 84, 094024 (2011). A.H. Fariborz, R. Jora, J. Schechter and M.N. Shahid, ``Chiral Nonet Mixing in pi-pi Scattering,'' Physical Review D 84, 113004 (2011).
Schubert, K.R.
1988-11-20
The third generation of quarks, anticipated in 1973 by Kobayashi and Maskawa as one of the possibilities to explain CP violation of the K/sup o/-meson system within the framework of the Standard Model and in 1975 by the discovery of the third generation of leptons, was found at FNAL in 1977. It showed up in form of the UPSILON(1S) resonance, the lowest-energy 1/sup - -/ state of the b-quark- anti-b-antiquark system. Experiments at DESY in 1978 showed that the b-quark has charge 1/3. These and further experiments showed that the b- anti-b system follows the same spectroscopic and strong-interaction rules as the c- anti-c system. The physics of the b- anti-b system has been studied extensively at the DESY e/sup +/e/sup -/ storage ring DORIS using the detectors DASP-II, PLUTO, LENA, Crystal Ball, and ARGUS, and from 1980 on at the Cronell e/sup +/e/sup -/ ring CESR using CLEO and CUSB. Today we know twelve states of the b- anti-b system in contrast to seven of the c- anti-c system and only four in the e/sup +/e/sup -/ bound state system positronium. (AIP)
Medium Modification of Vector Mesons
Chaden Djalali, Michael Paolone, Dennis Weygand, Michael H. Wood, Rakhsha Nasseripour
2011-03-01
The theory of the strong interaction, Quantum Chromodynamics (QCD), has been remarkably successful in describing high-energy and short-distance-scale experiments involving quarks and gluons. However, applying QCD to low energy and large-distance scale experiments has been a major challenge. Various QCD-inspired models predict a partial restoration of chiral symmetry in nuclear matter with modifications of the properties of hadrons from their free-space values. Measurable changes such as a shift in mass and/or a change of width are predicted at normal nuclear density. Photoproduction of vector mesons off nuclei have been performed at different laboratories. The properties of the ρ, ω and φ mesons are investigated either directly by measuring their mass spectra or indirectly through transparency ratios. The latest results regarding medium modifications of the vector mesons in the nuclear medium will be discussed.
Interaction of eta mesons with nuclei.
Kelkar, N G; Khemchandani, K P; Upadhyay, N J; Jain, B K
2013-06-01
Back in the mid-1980s, a new branch of investigation related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta-meson producing reactions. The vast literature of experimental as well as theoretical works that studied various aspects of eta-producing reactions such as the π(+)n → ηp, pd → (3)Heη, p (6)Li → (7)Be η and γ (3)He → η X, to name a few, had but one objective in mind: to understand the eta-nucleon (ηN) and hence the η-nucleus interaction which could explain the production data and confirm the existence of some η-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the ηN and hence the η-nucleus interaction. Therefore, this review is an attempt to bind together the findings in these works and draw some global and specific conclusions which can be useful for future explorations.The ηN scattering length (which represents the strength of the η-nucleon interaction) using different theoretical models and analyzing the data on η production in pion, photon and proton induced reactions was found to be spread out in a wide range, namely, 0.18 ≤ Re aηN ≤ 1.03 fm and 0.16 ≤ Rm aηN ≤ 0.49 fm. Theoretical searches of heavy η-mesic nuclei based on η-nucleus optical potentials and lighter ones based on Faddeev type few-body approaches predict the existence of several quasibound and resonant states. Although some hints of η-mesic states such as (3)(η)He and (25)(η)Mg do exist from previous experiments, the promise of clearer signals for the existence of η-mesic nuclei lies in the experiments to be performed at the J-PARC, MAMI and COSY facilities in the near future. This review is aimed at giving an overall status
Interaction of eta mesons with nuclei
NASA Astrophysics Data System (ADS)
Kelkar, N. G.; Khemchandani, K. P.; Upadhyay, N. J.; Jain, B. K.
2013-06-01
Back in the mid-1980s, a new branch of investigation related to the interaction of eta mesons with nuclei came into existence. It started with the theoretical prediction of possible exotic states of eta mesons and nuclei bound by the strong interaction and later developed into an extensive experimental program to search for such unstable states as well as understand the underlying interaction via eta-meson producing reactions. The vast literature of experimental as well as theoretical works that studied various aspects of eta-producing reactions such as the π+n → ηp, pd → 3Heη, p 6Li → 7Be η and γ 3He → η X, to name a few, had but one objective in mind: to understand the eta-nucleon (ηN) and hence the η-nucleus interaction which could explain the production data and confirm the existence of some η-mesic nuclei. In spite of these efforts, there remain uncertainties in the knowledge of the ηN and hence the η-nucleus interaction. Therefore, this review is an attempt to bind together the findings in these works and draw some global and specific conclusions which can be useful for future explorations. The ηN scattering length (which represents the strength of the η-nucleon interaction) using different theoretical models and analyzing the data on η production in pion, photon and proton induced reactions was found to be spread out in a wide range, namely, 0.18 ⩽ ℜe aηN ⩽ 1.03 fm and 0.16 ⩽ ℑm aηN ⩽ 0.49 fm. Theoretical searches of heavy η-mesic nuclei based on η-nucleus optical potentials and lighter ones based on Faddeev type few-body approaches predict the existence of several quasibound and resonant states. Although some hints of η-mesic states such as ^3_{\\eta} He and ^{25}_{\\eta} Mg do exist from previous experiments, the promise of clearer signals for the existence of η-mesic nuclei lies in the experiments to be performed at the J-PARC, MAMI and COSY facilities in the near future. This review is aimed at giving an overall
Volk, Alexei; /Dresden, Tech. U.
2010-08-26
The study of the semileptonic B-meson decays is the most accessible and cleanest way to determine the CKM matrix elements |V{sub cb}| and V{sub ub}. These decays also provide experimental access to study the QCD form-factors, heavy quark masses, and HQE parameters. The theoretical description of semileptonic B-meson decays at the parton level is very simple because there is no interaction between leptonic and hadronic currents. At the hadron level one needs to introduce corrections due to the strong interaction between quarks. Especially in the description of the inclusive B-meson decays the motion of the b-quark inside the B-meson plays a crucial role. All these effects are described in the frameworks of Heavy Quark Effective Theory (HQET) and Lattice QCD (LQCD). We give an overview about results of studies of semileptonic B-meson decays collected with the BABAR and Belle detectors at the PEP-II and the KEKB e{sup +}e{sup -}-storage rings. We present recent results on hadronic moments measured in inclusive B {yields} X{sub c}lv and B {yields} X{sub u}lv decays and extracted heavy quark masses m{sub b} and m{sub c} and dominant non-perturbative Heavy Quark Expansion (HQE) parameters. We also report the measurements of the CKM matrix elements |V{sub cb}| and |V{sub ub}| in inclusive and in exclusive semileptonic B-meson decays. We describe the studies of the form-factor parameters for the decay B{sup 0} {yields} D*{sup -}l{sup +}v and present the measurement of the B{sup 0} {yields} {pi}{sup -}l{sup +}v form-factor shape.
Meson spectroscopy with unitary coupled-channels model for heavy-meson decay into three mesons
Satoshi Nakamura
2012-04-01
We develop a model for describing excited mesons decay into three mesons. The properties of the excited mesons can be extracted with this model. The model maintains the three-body unitarity that has been missed in previous data analyses based on the conventional isobar models. We study an importance of the three-body unitarity in extracting hadron properties from data. For this purpose, we use the unitary and isobar models to analyze the same pseudo data of {gamma}p {yields} {pi}{sup +}{pi}{sup +}{pi}{sup -}n, and extract the properties of excited mesons. We find a significant difference between the unitary and isobar models in the extracted properties of excited mesons, such as the mass, width and coupling strength to decay channels. Hadron properties such as quantum numbers (spin, parity, etc.), mass and (partial) width have been long studied as a subject called hadron spectroscopy. The hadron properties provide important information for understanding internal structure of the hadron and dynamics which governs it. The dynamics here is of course QCD in its nonperturbative regime. The hadron properties can be extracted from data through a careful analysis, in many cases, partial wave analysis (PWA). Thus it is essential for hadron spectroscopy to have a reliable theoretical analysis tool.
Beauty meson decays to charmonium
NASA Astrophysics Data System (ADS)
Ershov, Alexey Valerievich
2001-10-01
We study decays of beauty (B) mesons into the final states containing charmonium mesons. The data were collected by the CLEO experiment at the Cornell Electron Storage Ring from 1990 to 1999. First, we describe a technique that significantly improves the reconstruction efficiency for decays of J/ y and y (2S) mesons into a pair of leptons. This reconstruction method is used in all the analyses presented in this dissertation. Then we present a study of B decays to the χc 1 and χc2 charmonium states and compare our results with the predictions of different theoretical models of charmonium production. After that we report the first observation of the decay B --> J/ y φK, which is the first B meson decay requiring a creation of an additional ss¯ quark pair. Then we measure the B0 and B+ meson masses from B0 --> y (') K0S and B+ --> y (') K+ decays. The method employed eliminates the dominant systematic uncertainty associated with the previous B meson mass measurements at the e+e- colliders and results in a significant improvement in precision. After that we present a study of three B0 decay modes useful for time-dependent CP asymmetry measurements. In this study we reconstruct B0 --> J/ y K0S , B0 --> χc 1 K0S , and B0 --> J/ y π0 decays. The latter two decay modes are observed for the first time. We describe a K0S --> π0π0 detection technique and its application to the reconstruction of the decay B 0 --> J/ y K0S . Then we present a sensitivity study for the measurement of the mixing-induced CP violation in the neutral B meson system (parameter sin 2β) at CLEO using the method that requires a measurement of the decay time of only one meson in a B0overline B0 pair. Finally, we search for direct CP violation in decays B+/- --> J/ y K+/- and B +/- --> y (2S) K+/- . The results of this search are consistent with the Standard Model expectations and provide the first experimental test of the assumption that direct CP violation is negligible in B --> y (') K decays.
Quantum Electrodynamics for Vector Mesons
Djukanovic, Dalibor; Schindler, Matthias R.; Scherer, Stefan; Gegelia, Jambul
2005-07-01
Quantum electrodynamics for {rho} mesons is considered. It is shown that, at the tree level, the value of the gyromagnetic ratio of the {rho}{sup +} is fixed to 2 in a self-consistent effective quantum field theory. Further, the mixing parameter of the photon and the neutral vector meson is equal to the ratio of electromagnetic and strong couplings, leading to the mass difference M{sub {rho}}{sub {sup 0}}-M{sub {rho}}{sub {sup {+-}}}{approx}1 MeV at tree order.
NASA Astrophysics Data System (ADS)
Albrecht, H.; Hamacher, T.; Hofmann, R. P.; Kirchhoff, T.; Mankel, R.; Nau, A.; Nowak, S.; Schröder, H.; Schulz, H. D.; Walter, M.; Wurth, R.; Hast, C.; Kapitza, H.; Kolanoski, H.; Kosche, A.; Lange, A.; Lindner, A.; Schieber, M.; Siegmund, T.; Spaan, B.; Thurn, H.; Töpfer, D.; Wegener, D.; Eckstein, P.; Schubert, K. R.; Schwierz, R.; Waldi, R.; Reim, K.; Wegener, H.; Eckmann, R.; Kuipers, H.; Mai, O.; Mundt, R.; Oest, T.; Reiner, R.; Schmidt-Parzefall, W.; Stiewe, J.; Werner, S.; Ehret, K.; Hofmann, W.; Hüpper, A.; Knöpfle, K. T.; Spengler, J.; Krieger, P.; Macfarlane, D. B.; Saull, P. R. B.; Tzamariudaki, K.; van de Water, R. G.; Yoon, T.-S.; Frankl, C.; Reßing, D.; Schmidtler, M.; Schneider, M.; Weseler, S.; Kernel, G.; Križan, P.; Križnič, E.; Podobnik, T.; Živko, T.; Balagura, V.; Belyaev, I.; Schechelnitsky, S.; Danilov, M.; Doutskoy, A.; Gershtein, Yu.; Golutvin, A.; Korolko, I.; Kostina, G.; Litvintsev, D.; Lubimov, V.; Pakhlov, P.; Semenov, S.; Snizhko, A.; Tichomirov, I.; Zaitsev, Yu.
1995-06-01
Using the ARGUS detector at the storage ring DORIS II we have measured τ decays into three charged mesons containing K * mesons. Exploiting the good particle identification capabilities of the detector we have determined the following branching ratios:Brleft( {tau ^ - to overline {K^{*0} } π ^ - v_tau } right) = left( {0.25 ± 0.10 ± 0.05} right)% , B r (τ-→ K *0 K - v τ)= (0.20±0.05±0.04)%, and B r (τ-→ K *- X 0 v τ) =(1.15±0.15-0.18 +0.13)%.
Electromagnetic Meson Production in the Nucleon Resonance Region
Volker Burkert; T.-S. H. Lee
2004-10-01
Recent experimental and theoretical advances in investigating electromagnetic meson production reactions in the nucleon resonance region are reviewed. The article gives a description of current experimental facilities with electron and photon beams and presents a unified derivation of most of the phenomenological approaches being used to extract the resonance parameters from the data. The analyses of {pi} and {eta} production data and the resulting transition form factors for the {Delta}(1232)P{sub 33}, N(1535)S{sub 11}, N(1440)P{sub 11}, and N(1520)D{sub 13} resonances are discussed in detail. The status of our understanding of the reactions with production of two pions, kaons, and vector mesons is also reviewed.
Photon-tagged heavy meson production in high energy nuclear collisions
Kang, Z.B.; Vitev, I.
2011-07-26
We study the photon-triggered light and heavy meson production in both p+p and A+A collisions. We find that a parton energy loss approach that successfully describes inclusive hadron attenuation in nucleus-nucleus reactions at RHIC can simultaneously describe well the experimentally determined photon-triggered light hadron fragmentation functions. Using the same framework, we generalize our formalism to study photon-triggered heavy meson production. We find that the nuclear modification of photon-tagged heavy meson fragmentation functions in A+A collision is very different from that of the photon-tagged light hadron case. While photon-triggered light hadron fragmentation functions in A+A collisions are suppressed relative to p+p, photon-triggered heavy meson fragmentation functions can be either enhanced or suppressed, depending on the specific kinematic region. The anticipated smaller energy loss for b-quarks manifests itself as a flatter photon-triggered B-meson fragmentation function compared to that for the D-meson case. We make detailed predictions for both RHIC and LHC energies. We conclude that a comprehensive comparative study of both photon-tagged light and heavy meson production can provide new insights in the details of the jet quenching mechanism.
Theoretical overview: The New mesons
Quigg, Chris; /Fermilab
2004-11-01
After commenting on the state of contemporary hadronic physics and spectroscopy, I highlight four areas where the action is: searching for the relevant degrees of freedom, mesons with beauty and charm, chiral symmetry and the D{sub sJ} levels, and X(3872) and the lost tribes of charmonium.
Amiri, F.
1985-04-01
We present a systematic study of the valon distribution functions and valon structure functions for pions and kaons. The implications of our results for low-p/sub T/ inclusive reactions are emphasized. The complications with the structure function of strange valons are discussed and suggestions are made for future experiments to extract it from the structure function of kaons at high Q/sup 2/.
Role of pion pole in hard exlusive meson leptoproduction
NASA Astrophysics Data System (ADS)
Goloskokov, Sergey
2016-02-01
We consider the pion pole contribution and transversity effects determined by the HT and ĒT Generalized Parton Distributions (GPDs) which are essential in hard pseudoscalar and vector meson leptoproduction. We investigate spin effects in the ω and ρ0 reactions. It is shown that the pion pole contribution is very important in the w production. Such effects in the ρ0 channel are much smaller. Our results on spin asymmetries and spin density matrix elements in these reactions were found to be in good agreement with HERMES data.
Photoproduction of $\\pi^+ \\pi^-$ meson pairs on the proton
Marco A. Battaglieri; DeVita, Raffaella; Szczepaniak, Adam P.
2009-10-01
The exclusive reaction $\\gamma p \\to p \\pi^+ \\pi^-$ was studied in the photon energy range 3.0 - 3.8 GeV and momentum transfer range $0.4<-t<1.0$ GeV$^2$. Data were collected with the CLAS detector at the Thomas Jefferson National Accelerator Facility. In this kinematic range the integrated luminosity was about 20 pb$^{-1}$. The reaction was isolated by detecting the $\\pi^+$ and proton in CLAS, and reconstructing the $\\pi^-$ via the missing-mass technique. Moments of the di-pion decay angular distributions were derived from the experimental data. Differential cross sections for the $S$, $P$, and $D$-waves in the $M_{\\pi^+\\pi^-}$ mass range $0.4-1.4$ GeV were derived performing a partial wave expansion of the extracted moments. Besides the dominant contribution of the $\\rho(770)$ meson in the $P$-wave, evidence for the $f_0(980)$ and the $f_2(1270)$ mesons was found in the $S$ and $D$-waves, respectively. The differential production cross sections $d\\sigma/dt$ for individual waves in the mass range of the above-mentioned mesons were extracted. This is the first time the $f_0(980)$ has been measured in a photoproduction experiment.
Eta(547) and Eta(958) Meson Photoproduction on the Proton
Michael Dugger
2001-12-01
Photoproduction of {eta} and {eta}{prime} mesons has been studied at the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) using a tagged photon beam incident on a hydrogen target with photon energies from the respective production thresholds up to 2.4 GeV. The photoproduced mesons were identified via missing mass reconstruction using recoil proton momentum and time of flight information. Data were obtained in a range of {radical}s from threshold to 2.2 GeV for each meson. In this study, differential cross-section measurements for the {gamma}p {yields} p{eta} and {gamma}p {yields} p{eta}{prime} reactions are presented, and the results compared to recent data. An isobar analysis of the differential cross-sections is performed. The predicted differential cross-sections from the isobar analysis are used to predict behavior in unmeasured regions of phase space, and to infer total cross sections. For the {gamma}p {yields} p{eta} reaction, a value of the S{sub 11}(1535) proton helicity amplitude also was extracted and compared to recent analyses. The data presented greatly extends the energy and angle coverage for differential cross-sections of {eta} photoproduction, and significantly improves the accuracy with which {eta}{prime} cross sections are known.
Dynamical coupled channel calculation of pion and omega meson production
Paris, Mark
2009-01-01
A dynamical coupled channel approach is used to study $\\pi$ and $\\omega$--meson production induced by pions and photons scattering from the proton. Six-channels are used to fit unpolarized and polarized scattering data including $\\pi N$, $\\eta N$, $\\pi\\Delta$, $\\sigma N$, $\\rho N$, $\\omega N$. Bare parameters in an effective hadronic Lagrangian are fixed in $\\chi^2$-fits to data from $\\pi N \\to \\pi N$, $\\gamma N \\to \\pi N$, $\\pi^- p \\to \\omega n$, and $\\gamma p \\to \\omega p$ reactions at center-of-mass energies from threshold to $E < 2.0$ GeV. The $T$ matrix determined in these fits is used to calculate the photon beam asymmetry for $\\omega$-meson production and the $\\omega N \\to \\omega N$ total cross section and scattering lengths.
D and E mesons and possible KKK enhancements
Bromberg, C.; Dickey, J.; Fox, G.; Gomez, R.; Kropac, W.; Pine, J.; Stampke, S.; Haggerty, H.; Malamud, E.; Abrams, R.; Delzenero, R.; Goldberg, H.; Lopez, F.; Margulies, S.; McLeod, D.; Solomon, J.; Dzierba, A.; Fredericksen, F.; Heinz, R.; Krider, J.; Martin, H.; Petersen, D.
1981-01-01
Results are presented from the study of multikaon final states in the reactions ..pi../sup -/p..-->..K/sup 0/K/sup + -/..pi..minus-or-plusX, K/sup 0/K/sup +/KX at 50 and 100 GeV/c. Here X is semi-inclusive, because a specific forward topology and an interaction registering in the counters sourrounding the target are required. The D(1285) meson is seen in the dr mode, while the E(1420) meson is observed in both the dr and the KK modes. In addition, there are two possible enhancements in the three kaon final state. The first (Mapprox.1840 MeV) is associated with the K/sup 0/f mode and is consistent with being the charmed D/sup 0/. The second, a K state (M = 2003 +- 14 MeV, G = 87 +- 43 MeV), decays into KA/sub 2/.
Lazzaro, Alfio; /Milan U. /INFN, Milan
2007-05-11
Symmetries and their conservation laws play a fundamental role in Physics. Among them, the discrete symmetries corresponding to charge (C), parity (P), and time (T) transformations are extensively used in the theory of the elementary particles and their interactions (so called Standard Model (SM)) to give the basis of the fundamental physical description of nature. Eventual discoveries of violations of these symmetries become a crucial test for our understanding of the nature. It was assumed that the three discrete symmetries were not violated until 1956 when it was found that P is violated in the weak interaction. Soon it was understood that also the C is violated in the weak interaction. At that time these two violated symmetries were replaced by their combination, CP, which was considered a new fundamental symmetry. In 1964 also the CP was found violated in the case of the neutral K meson system. Since that year there were many achievements in theories and experiments in order to explain this symmetry violation. In the last five years the main contribution comes from the discovery of the CP violation in B meson system. In this note we will describe briefly how the CP violation is described in the SM and the main experimental results obtained in the B mesons system.
Dynamical meson melting in holography
NASA Astrophysics Data System (ADS)
Ishii, Takaaki; Kinoshita, Shunichiro; Murata, Keiju; Tanahashi, Norihiro
2014-04-01
We discuss mesons in thermalizing gluon backgrounds in the = 2 super-symmetric QCD using the gravity dual. We numerically compute the dynamics of a probe D7-brane in the Vaidya-AdS geometry that corresponds to a D3-brane background thermalizing from zero to finite temperatures by energy injection. In static backgrounds, it has been known that there are two kinds of brane embeddings where the brane intersects the black hole or not. They correspond to the phases with melted or stable mesons. In our dynamical setup, we obtain three cases depending on final temperatures and injection time scales. The brane stays outside of the black hole horizon when the final temperature is low, while it intersects the horizon and settles down to the static equilibrium state when the final temperature is high. Between these two cases, we find the overeager case where the brane dynamically intersects the horizon although the final temperature is not high enough for a static brane to intersect the horizon. The interpretation of this phenomenon in the dual field theory is meson melting due to non-thermal effects caused by rapid energy injection. In addition, we comment on the late time evolution of the brane and a possibility of its reconnection.
Meson Spectroscopy at CLAS and CLAS12
Carlos Salgado
2011-10-01
We report on meson spectroscopy using the CLAS at Jefferson Lab. We study photo-production of exotic mesons and strangeonia on the largest data sample ever to be produced at photon energies of about 5 GeV. We also describe an experiment to continue meson spectroscopy at CLAS12 (CLAS energy upgrade) using electroproduction at very low Q2 ('quasireal photons') up to photon energies of 10 GeV.
Some recent results on meson spectroscopy
Chung, S.U.
1987-06-01
A comparative survey of established meson states with the predictions of a q anti q (quarkonium) model by Godfrey and Isgur shows that most meson states are well described, from pion to UPSILON(6S). However, a number of states in the light- quark isoscalar sector are not predicted at all in their model, pointing to a need for glueballs, hybrids and multi-quark states to fully account for recently reported meson states. 48 refs.
Spin alignment of vector mesons in heavy ion and proton-proton collisions
NASA Astrophysics Data System (ADS)
Ayala, Alejandro; Cuautle, Eleazar; Corral, G. Herrera; Magnin, J.; Montaño, Luis Manuel
2010-01-01
The spin alignment matrix element ρ00 for the vector mesons K and ϕ(1020) has been measured in RHIC at central rapidities. These measurements are consistent with the absence of polarization with respect to the reaction plane in mid-central Au+Au collisions whereas, when measured with respect to the production plane in the same reactions and in p+p collisions, a non-vanishing and p⊥-dependent ρ00 is found. We show that this behavior can be understood in a simple model of vector meson production where the spin of their constituent quarks is oriented during hadronization as the result of Thomas precession.
Indirect evidences for existence of exotic mesons in hadronic weak decays of K and charm mesons
Terasaki, K.
1998-05-29
It is demonstrated that hadronic weak decays of K and charm mesons are intimately related to hadron spectroscopy. Long standing puzzles in hadronic weak decays of charm mesons can be solved by taking account of dynamical contributions of various hadrons including non-qq-bar mesons.
Meson's correlation functions in a nuclear medium
NASA Astrophysics Data System (ADS)
Park, Chanyong
2016-09-01
We investigate meson's spectrum, decay constant and form factor in a nuclear medium through holographic two- and three-point correlation functions. To describe a nuclear medium composed of protons and neutrons, we consider a hard wall model on the thermal charged AdS geometry and show that due to the isospin interaction with a nuclear medium, there exist splittings of the meson's spectrum, decay constant and form factor relying on the isospin charge. In addition, we show that the ρ-meson's form factor describing an interaction with pseudoscalar fluctuation decreases when the nuclear density increases, while the interaction with a longitudinal part of an axial vector meson increases.
Vector meson masses in nuclear medium
NASA Astrophysics Data System (ADS)
Morones-Ibarra, Jose Ruben
1998-11-01
In this work I carry out theoretical calculations of the Rho meson mass in nuclear medium when it couples to two pions which strongly couple to in medium N/wedge/*N/wedge([-]1) states. The calculations are done from the modified Rho meson propagator in a non-relativistic approximation. Defining the Rho meson mass as the position of the peak of the spectral function, we find that there is an increase of the Rho meson mass as the density of the nuclear medium augments. The width of the spectral function becomes larger and the peak height is reduced with increasing nuclear densities.
Inclusive meson production in 3.5 GeV pp collisions studied with the HADES spectrometer
NASA Astrophysics Data System (ADS)
Rustamov, Anar
2010-08-01
We present the inclusive di-electron invariant-mass spectrum from p+p interactions at 3.5 GeV kinetic beam energy. It is a very important reference for the study of vector meson production off the nucleus, recently investigated by HADES in p+93Nb reactions at the same beam energy. Up to invariant masses of 0.6 GeV/c2 the main contributions to the e+e- spectrum are π0, η, ω and Δ Dalitz decays. In the vector-meson region a clear peak corresponding to the ω direct decay is reconstructed with ≈2% mass resolution. Subtracting this peak from the spectrum allows to investigate additional sources, in particular the ρ meson. Indeed, the latest results from HSD and UrQMD calculations show different distributions for the shape of the ρ meson at these energies. Therefore it is important to experimentally understand the production mechanism of the ρ meson in elementary reactions. Besides the spectral shape of the mesons, their inclusive production cross sections are also not known at these energies. Due to the large and flat acceptance of the HADES spectrometer for e+e- masses above 0.2 GeV/c2 and for PT<1GeV/c, acceptance corrections are to a large extent model independent. This allows us to extract the preliminary inclusive cross section values for the meson productions at these energies.
N.I. Kochelev, M. Battaglieri, R. De Vita
2009-08-01
We calculated the exclusive f1(1285) meson photoproduction cross section at an energy of a few GeV within the Regge approach. The calculation shows that the cross section is sizable, being in the range of 100 nb, and much larger than the expected cross section of the eta(1295) meson photoproduction at the same energy. These two facts make it possible to use this reaction to study the poor known properties of the f1(1285) meson in the JLab kinematics.
The impact of vector mesons polarization on meson-nucleon interaction
NASA Astrophysics Data System (ADS)
Gevorkyan, Sergey
2016-02-01
Production of unstable particles off nuclei allows to determine the total cross section of the unstable particle interaction with nucleons. The interaction of vector mesons V(ρ, ω, ϕ) with nucleons are defined by a set of amplitudes corresponding to the transverse polarization of the vector meson (helicity λ = ±1) meson or longitudinal one (λ = 0). Whereas the total cross section for the interaction of the transversely polarized vector meson with nucleon σ T = σ(VTN) can be extract from the coherent photoproduction, measurements of vector meson interaction with nucleon σL= σ(VLN). As a good tool for such investigation we proposed the photoproduction of ω mesons on the set of nuclei in the incoherent region. Such experiment can be done using the feasibility of the new experiment GlueX at Jefferson Lab, designed to study the photoproduction of mesons in a large beam energy range up to 12 GeV.
Rescattering in Meson Photoproduction off Few Body Systems
Jean-Marc Laget
2006-04-01
Exclusive reactions induced at high momentum transfer in few body systems allow to adjust the formation time of the produced particles to the distance between two nucleons in the target. They are the best windows to study the propagation of exotic configurations of hadrons such as for instance the onset of color transparency. It may appear earlier in meson photo-production reactions, in the strange sector more particularly, than in more classical quasi elastic scattering of electrons. More generally, those reactions provide them with the best tool to determine the cross section of the scattering of various hadrons (strange particles, vector mesons) with nucleon, to better understand the mechanisms of their formation in cold hadronic matter, and to access the production of possible exotic states. At the top of the unitary rescattering peak (triangular logarithmic singularity), the reaction amplitude is on solid ground since it depends only on on-shell elementary amplitudes and on low momentum components of the nuclear wave function.
NASA Astrophysics Data System (ADS)
Roe, Natalie A.
2001-04-01
Our world manifestly violates CP, the symmetry between matter and antimatter; there is no observational evidence for any significant amount of antimatter in the Universe. Andrei Sakharov was the first to point out that, in the context of Big Bang theory, a matter-dominated universe requires CP violation at the quantum level. Indeed, CP violation was subsequently observed as a tiny effect in K-meson decays, and it can be naturally accommodated in the Standard Model of fundamental particles with 3 generations of quarks. However, to produce the observed baryon asymmetry, baryogenesis calculations require more CP violation than the Standard Model affords. This is an intriguing puzzle whose solution will require input from both particle physics and cosmology, and it has inspired particle physicists to study CP violation with greater precision in a new generation of experiments. We are now entering this exciting new era in CP violation studies. Several new or upgraded experiments plan a program of detailed measurements of CP violating effects in B mesons. The predicted asymmetries are large, observable in a variety of decay channels, and the theoretical uncertainties are small for the best modes. Some interesting experimental results have recently been announced, and more precise measurements will soon follow. Future experiments are already planned to make even more definitive measurements. In this talk I will review the theoretical predictions and the connection to cosmology, survey the experimental scene, and describe how the study of CP violation in B mesons will allow us to make stringent tests of the Standard Model.
Meson-photon transition form factors
Balakireva, Irina; Lucha, Wolfgang; Melikhov, Dmitri
2012-10-23
We present the results of our recent analysis of the meson-photon transition form factors F{sub P{gamma}}(Q{sup 2}) for the pseudoscalar mesons P {pi}{sup 0},{eta},{eta} Prime ,{eta}{sub c}, using the local-duality version of QCD sum rules.
Light scalar mesons in central production at COMPASS
NASA Astrophysics Data System (ADS)
Austregesilo, Alexander
2016-05-01
COMPASS is a fixed-target experiment at the CERN SPS that studies the spectrum of light-quark hadrons. In 2009, it collected a large dataset using a 190 GeV/c positive hadron beam impinging on a liquid-hydrogen target in order to measure the central exclusive production of light scalar mesons. One of the goals is the search for so-called glueballs, which are hypothetical meson-like objects without valence-quark content. We study the decay of neutral resonances by selecting centrally produced pion pairs from the COMPASS dataset. The angular distributions of the two pseudoscalar mesons are decomposed in terms of partial waves, where particular attention is paid to the inherent mathematical ambiguities. The large dataset allows us to perform a detailed analysis in bins of the two squared four-momentum transfers carried by the exchange particles in the reaction. Possible parameterisations of the mass dependence of the partial-wave amplitudes in terms of resonances are also discussed.
Heavy meson observables and Dyson Schwinger equations.
Ivanov, M. A.
1998-10-20
Dyson-Schwinger equation (DSE) studies show that the b-quark mass-function is approximately constant, and that this is true to a lesser extent for the c-quark. This observation provides the basis for a study of the leptonic and semileptonic decays of heavy pseudoscalar mesons using a ''heavy-quark'' limit of the DSES, which, when exact, reduces the number of independent form factors. Semileptonic decays with light mesons in the final state are also accessible because the DSES provide a description of light-quark propagation characteristics and light-meson structure. A description of B-meson decays is straightforward, however, the study of decays involving the D-meson indicates that c-quark mass-corrections are quantitatively important.
Excited light meson spectroscopy from lattice QCD
Christopher Thomas, Hadron Spectrum Collaboration
2012-04-01
I report on recent progress in calculating excited meson spectra using lattice QCD, emphasizing results and phenomenology. With novel techniques we can now extract extensive spectra of excited mesons with high statistical precision, including spin-four states and those with exotic quantum numbers. As well as isovector meson spectra, I will present new calculations of the spectrum of excited light isoscalar mesons, something that has up to now been a challenge for lattice QCD. I show determinations of the flavor content of these mesons, including the eta-eta' mixing angle, providing a window on annihilation dynamics in QCD. I will also discuss recent work on using lattice QCD to map out the energy-dependent phase shift in pi-pi scattering and future applications of the methodology to the study of resonances and decays.
Light Vector Mesons in the Nuclear Medium
Wood, Michael; Nasseripour, Rakhsha; Weygand, Dennis; Djalali, Chaden; Tur, Clarisse; Mosel, Ulrich; Muehlich, Pascal; Adams, Gary; Amaryan, Moscov; Amaryan, Moskov; Ambrozewicz, Pawel; Anghinolfi, Marco; Asryan, Gegham; Avagyan, Harutyun; Baghdasaryan, Hovhannes; Baillie, Nathan; Ball, James; Baltzell, Nathan; Barrow, Steve; Battaglieri, Marco; Bedlinskiy, Ivan; Bektasoglu, Mehmet; Bellis, Matthew; Benmouna, Nawal; Berman, Barry; Biselli, Angela; Blaszczyk, Lukasz; Bouchigny, Sylvain; Boyarinov, Sergey; Bradford, Robert; Branford, Derek; Briscoe, William; Brooks, William; Burkert, Volker; Butuceanu, Cornel; Calarco, John; Careccia, Sharon; Carman, Daniel; Carnahan, Bryan; Casey, Liam; Chen, Shifeng; Cheng, Lu; Cole, Philip; Collins, Patrick; Coltharp, Philip; Crabb, Donald; Crannell, Hall; Crede, Volker; Cummings, John; Dashyan, Natalya; De Vita, Raffaella; De Sanctis, Enzo; Degtiarenko, Pavel; Denizli, Haluk; Dennis, Lawrence; Deur, Alexandre; Dharmawardane, Kahanawita; Dickson, Richard; Dodge, Gail; Doughty, David; Dugger, Michael; Dytman, Steven; Dzyubak, Oleksandr; Egiyan, Hovanes; Egiyan, Kim; Elfassi, Lamiaa; Elouadrhiri, Latifa; Eugenio, Paul; Fedotov, Gleb; Feldman, Gerald; Feuerbach, Robert; Fradi, Ahmed; Funsten, Herbert; Garcon, Michel; Gavalian, Gagik; Gilfoyle, Gerard; Giovanetti, Kevin; Girod, Francois-Xavier; Goetz, John; Gordon, Christopher; Gothe, Ralf; Griffioen, Keith; Guidal, Michel; Guler, Nevzat; Guo, Lei; Gyurjyan, Vardan; Hadjidakis, Cynthia; Hafidi, Kawtar; Hakobyan, Hayk; Hakobyan, Rafael; Hanretty, Charles; Hardie, John; Hassall, Neil; Hersman, F.; Hicks, Kenneth; Hleiqawi, Ishaq; Holtrop, Maurik; Hyde, Charles; Ilieva, Yordanka; Ireland, David; Ishkhanov, Boris; Isupov, Evgeny; Ito, Mark; Jenkins, David; Jo, Hyon-Suk; Johnstone, John; Joo, Kyungseon; Juengst, Henry; Kalantarians, Narbe; Kellie, James; Khandaker, Mahbubul; Khetarpal, Puneet; Kim, Wooyoung; Klein, Andreas; Klein, Franz; Klimenko, Alexei; Kossov, Mikhail; Krahn, Zebulun; Kramer, Laird; Kubarovsky, Valery; Kuhn, Joachim; Kuhn, Sebastian; Kuleshov, Sergey; Lachniet, Jeff; Laget, Jean; Langheinrich, Jorn; Lawrence, David; Li, Ji; Livingston, Kenneth; Lu, Haiyun; MacCormick, Marion; Markov, Nikolai; Mattione, Paul; McAleer, Simeon; McKinnon, Bryan; McNabb, John; Mecking, Bernhard; Mehrabyan, Surik; Melone, Joseph; Mestayer, Mac; Meyer, Curtis; Mibe, Tsutomu; Mikhaylov, Konstantin; Minehart, Ralph; Mirazita, Marco; Miskimen, Rory; Mokeev, Viktor; Moriya, Kei; Morrow, Steven; Moteabbed, Maryam; Mueller, James; Munevar Espitia, Edwin; Mutchler, Gordon; Nadel-Turonski, Pawel; Niccolai, Silvia; Niculescu, Gabriel; Niculescu, Maria-Ioana; Niczyporuk, Bogdan; Niroula, Megh; Niyazov, Rustam; Nozar, Mina; Osipenko, Mikhail; Ostrovidov, Alexander; Park, Kijun; Pasyuk, Evgueni; Paterson, Craig; Pereira, Sergio; Pierce, Joshua; Pivnyuk, Nikolay; Pocanic, Dinko; Pogorelko, Oleg; Pozdnyakov, Sergey; Preedom, Barry; Price, John; Prok, Yelena; Protopopescu, Dan; Raue, Brian; Riccardi, Gregory; Ricco, Giovanni; Ripani, Marco; Ritchie, Barry; Ronchetti, Federico; Rosner, Guenther; Rossi, Patrizia; Sabatie, Franck; Salamanca, Julian; Salgado, Carlos; Santoro, Joseph; Sapunenko, Vladimir; Schumacher, Reinhard; Serov, Vladimir; Sharabian, Youri; Sharov, Dmitri; Shvedunov, Nikolay; Smith, Elton; Smith, Lee; Sober, Daniel; Sokhan, Daria; Stavinsky, Aleksey; Stepanyan, Stepan; Stepanyan, Samuel; Stokes, Burnham; Stoler, Paul; Strakovski, Igor; Strauch, Steffen; Taiuti, Mauro; Tedeschi, David; Tkabladze, Avtandil; Tkachenko, Svyatoslav; Todor, Luminita; Ungaro, Maurizio; Vineyard, Michael; Vlassov, Alexander; Watts, Daniel; Weinstein, Lawrence; Williams, Michael; Wolin, Elliott; Yegneswaran, Amrit; Zana, Lorenzo; Zhang, Bin; Zhang, Jixie; Zhao, Bo; Zhao, Zhiwen
2008-07-01
The light vector mesons ($\\rho$, $\\omega$, and $\\phi$) were produced in deuterium, carbon, titanium, and iron targets in a search for possible in-medium modifications to the properties of the $\\rho$ meson at normal nuclear densities and zero temperature. The vector mesons were detected with the CEBAF Large Acceptance Spectrometer (CLAS) via their decays to $e^{+}e^{-}$. The rare leptonic decay was chosen to reduce final-state interactions. A combinatorial background was subtracted from the invariant mass spectra using a well-established event-mixing technique. The $\\rho$ meson mass spectrum was extracted after the $\\omega$ and $\\phi$ signals were removed in a nearly model-independent way. Comparisons were made between the $\\rho$ mass spectra from the heavy targets ($A > 2$) with the mass spectrum extracted from the deuterium target. With respect to the $\\rho$-meson mass, we obtain a small shift compatible with zero. Also, we measure widths consistent with standard nuclear many-body eff
SUITABILITY OF A NEW CALORIMETER FOR EXOTIC MESON SEARCHES
Bookwalter, C.; Ostrovidov, A.; Eugenio, P.
2007-01-01
Exotic mesons, particles that have quantum numbers that are inaccessible to conventional quark-model mesons, are predicted by quantum chromodynamics (QCD), but past experiments seeking to identify exotic candidates have produced controversial results. The HyCLAS experiment (E04005) at Thomas Jefferson National Accelerator Facility (TJNAF) proposes the use of the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) in Hall B to study the photoproduction of exotic mesons. However, the base detector package at CLAS is not ideal for observing and measuring neutral particles, particularly at forward angles. The Deeply Virtual Compton Scattering (DVCS) experiment at TJNAF has commissioned a new calorimeter for detecting small-angle photons, but studies must be performed to determine its suitability for a meson spectroscopy experiment. The ηπ system has been under especial scrutiny in the community as a source for potential exotics, so the new calorimeter’s ability at reconstructing these resonances must be evaluated. To achieve this, the invariant mass of showers in the calorimeter are reconstructed. Also, two electroproduction reaction channels analogous to photoproduction channels of interest to HyCLAS are examined in DVCS data. It is found that, while not ideal, the new calorimeter will allow access to additional reaction channels, and its inclusion in HyCLAS is warranted. Results in basic shower reconstruction show that the calorimeter has good effi ciency in resolving π° decays, but its η reconstruction is not as strong. When examining ep → epπ°η, preliminary reconstruction of the ηπ° system shows faint signals in the a0(980) region. In the ep → e n π+ η channel, preliminary reconstruction of the ηπ+ system gave good signals in the a0(980) and a2(1320) regions, but statistics were poor. While more analyses are necessary to improve statistics and remove background, these preliminary results support the claim
Semileptonic decays of B meson into charmed meson
Katayama, N. )
1989-12-15
Recent results on semileptonic decays of {ital B} meson into charmed meson using the CLEO detector at CESR are summarized. Ratios of the inclusive semileptonic branching fractions, B(B{sup {minus}}{r arrow}{ital D}{sup 0}{ital Xl}{sup {minus}}{bar {nu}}), B({ital {bar B}}{sup 0}{r arrow}{ital D}{sup +}{ital Xl}{sup {minus}}{bar {nu}}{ital Xl}{sup {minus}}{bar {nu}}), and B({ital {bar B}}{sup 0}{r arrow}{ital D}{sup +}) average {ital B} meson semileptonic branching fraction are reported. The branching fractions of the exclusive final states, {ital B}{sup {minus}}{r arrow}{ital D}{sup 0}{ital l}{sup {minus}}{bar {nu}}, {ital B}{sup {minus}}{r arrow}{ital D}{sup 0}{ital l}{sup {minus}}{bar {nu}}, and {ital {bar B}}{sup 0}{r arrow}{ital D}{sup +}{ital l}{sup {minus}}{bar {nu}} are measured. The ratio of B({ital B}{sup {minus}}{r arrow}{ital D}{sup 0}{ital l}{sup {minus}}{bar {nu}}) to B(B{sup {minus}}{r arrow}{ital D}{sup 0}{ital l}{sup {minus}}{bar {nu}}) and the polarization of the {ital D}*{sup +} are obtained and compared with theoretical models. The value of {vert bar}{ital V}{sub {ital c}{ital b}}{vert bar} is calculated from the exclusive branching fractions for various models. Finally, the lifetime ratio of the charged and neutral {ital B}'s ({tau}{sup +}/{tau}{sup 0}) is determined from the ratio of B({ital B}{sup {minus}}{r arrow}{ital D}{sup 0}{ital l}{sup {minus}}{bar {nu}}) to B({ital {bar B}}{sup 0}{r arrow}{ital D}{sup +}{ital l}{sup {minus}}{bar {nu}}) to be 0.85{plus minus}0.20{sup +0.22}{sub {minus}0.16}.
A search for the Bs meson in Υ(5S) decays
NASA Astrophysics Data System (ADS)
Shipsey, Ian
2004-05-01
The CLEO III detector has recorded approximately 0.5 fb-1 of e^+ e^- annihilation data at the Υ(5S) resonance. Using this data sample, we have searched for fully reconstructed Bs mesons in the reaction Υ(5S) arrow B_s^(*) barB_s^(*)
1988 CELLO, JADE, and PLUTO contributions to ''exotic'' meson spectroscopy
Feindt, M.
1989-04-25
This article reviews selected recent results on resonance formation in ..gamma gamma.. reactions obtained with the CELLO, JADE, and PLUTO spectrometers at the /ital e//sup +//ital e/minus// storage ring PETRA. New stringent limits on the ..gamma gamma.. coupling of glueball candidates as well as new results on tensor and scalar mesons are presented. The recent observation of ..pi../sub 2/(1680) formation is confirmed by the CELLO group. Finally the two spin 1 states observed in ..gamma gamma../sup */ interactions, in particular the parity of the /ital X//sub 1/(1420) and the model dependence of present analyses are discussed.
Exotic mesons in /bar N/N annihilation
Dover, C.B.
1988-01-01
We investigate the utility of the antinucleon-nucleon (/bar N/N) annihilation process as a means of producing exotic (non /bar Q/Q) mesons. Several examples are considered of J/sup ..pi..//sup C/ exotic formation in the /bar p/p ..-->.. ..pi..X reaction. We emphasize the usefulness of quantum number filtration, achieved by preparing the initial /bar p/p atom in tagged L = 0,1 states and focusing on selected exclusive final states. 36 refs., 4 tabs.
Photoproduction of the rho meson and its magnetic moments
Kaneko, Hiromi; Hosaka, Atsushi; Scholten, Olaf
2011-10-21
We study photoproduction of {rho} meson in a model of hidden local symmetry. We introduce the {rho} meson on a hidden gauge boson and phenomenological {rho} meson-nucleon Lagrangian is constructed respecting chiral symmetry. It turns out that the {sigma}-exchange interaction plays an important role in neutral {rho} meson photoproduction to reproduce the experimental cross sections. In charged {rho} meson photoproduction, the model takes into account the {rho} meson magnetic moments from the three-point vertex in the kinetic terms. We show that the magnetic moment of the charged {rho} meson has a significant effect on the total cross sections in proportion to the photon energies.
GlueX: Meson Spectroscopy in Photoproduction
Salgado, Carlos; Smith, Elton S.
2014-03-01
The goal of the GlueX experiment \\cite{gluex} is to provide crucial data to help understand the soft gluonic fields responsible for binding quarks in hadrons. Hybrid mesons, and in particular exotic hybrid mesons, provide the ideal laboratory for testing QCD in the confinement regime since these mesons explicitly manifest the gluonic degrees of freedom. Photoproduction is expected to be effective in producing exotic hybrids but there is little data on the photoproduction of light mesons. GlueX will use the new 12-GeV electron beam at Jefferson Lab to produce a 9-GeV beam of linearly polarized photons using the technique of coherent bremsstrahlung. A solenoid-based hermetic detector is under construction, which will be used to collect data on meson production and decays. These data will also be used to study the spectrum of conventional mesons, including the poorly understood excited vector mesons. This talk will give an update on the experiment as well as describe theoretical developments \\cite{Dudek:2011bn} to help understand how these data can provide insights into the fundamental theory of strong interactions.
Investigation of the electromagnetic structure of η and η' mesons by two-photon interactions
NASA Astrophysics Data System (ADS)
Aihara, H.; Alston-Garnjost, M.; Avery, R. E.; Barbaro-Galtieri, A.; Barker, A. R.; Barnett, B. A.; Bauer, D. A.; Bay, A.; Bobbink, G. J.; Buchanan, C. D.; Buijs, A.; Caldwell, D. O.; Chao, H.-Y.; Chun, S.-B.; Clark, A. R.; Cowan, G. D.; Crane, D. A.; Dahl, O. I.; Daoudi, M.; Derby, K. A.; Eastman, J. J.; Eberhard, P. H.; Edberg, T. K.; Eisner, A. M.; Erné, F. C.; Fairfield, K. H.; Hauptman, J. M.; Hofmann, W.; Hylen, J.; Kamae, T.; Kaye, H. S.; Kenney, R. W.; Khacheryan, S.; Kofler, R. R.; Langeveld, W. G.; Layter, J. G.; Lin, W. T.; Linde, F. L.; Loken, S. C.; Lu, A.; Lynch, G. R.; Madaras, R. J.; Magnuson, B. D.; Masek, G. E.; Mathis, L. G.; Matthews, J. A.; Maxfield, S. J.; Miller, E. S.; Moses, W.; Nygren, D. R.; Oddone, P. J.; Paar, H. P.; Park, S. K.; Pellett, D. E.; Pripstein, M.; Ronan, M. T.; Ross, R. R.; Rouse, F. R.; Schwitkis, K. A.; Sens, J. C.; Shapiro, G.; Shen, B. C.; Smith, J. R.; Steinman, J. S.; Stephens, R. W.; Stevenson, M. L.; Stork, D. H.; Strauss, M. G.; Sullivan, M. K.; Takahashi, T.; Toutounchi, S.; van Tyen, R.; Vernon, W.; Wagner, W.; Wang, E. M.; Wang, Y.-X.; Wenzel, W. A.; Wolf, Z. R.; Yamamoto, H.; Yellin, S. J.; Zeitlin, C.; TPC/Two-Gamma Collaboration
1990-01-01
The TPC/Two-Gamma facility at the SLAC e+e- storage ring PEP was used to study the reactions γγ*-->η and γγ*-->η'. The ηγ*γ and η'γ*γ transition form factors were measured as functions of Q2, the negative of the invariant mass squared of the tagged photon, in the range 0.1
η ‑ η‧ mixing and decays of mesons with heavy quarks
NASA Astrophysics Data System (ADS)
Balitsky, Jaroslav V.; Kiselev, Valery V.; Likhoded, Anatoly K.; Samoylenko, Vladimir D.
2016-06-01
The inclusion of elastic rescattering and annihilation of quark-antiquarks pairs in final state can explain the t-dependency for cross-section ratio of η and η‧ mesons in charge exchange reaction. The estimation for mixing angle η ‑ η‧ with isoscalar states ūu + d¯d and hidden strangeness s¯s has been obtained. The consistent description of η and η‧ meson outputs in B0, Bs0 and J/ψ decays was also considered.
Photoproduction of ω mesons off nuclei and impact of polarization on the meson-nucleon interaction
NASA Astrophysics Data System (ADS)
Chudakov, E.; Gevorkyan, S.; Somov, A.
2016-01-01
We use photoproduction of ω mesons off complex nuclei to study interactions of transversely and longitudinally polarized vector mesons with nucleons. Whereas the total cross section for interactions of the transversely polarized vector mesons with nucleons σT=σ (VTN ) can be obtained from coherent photoproduction, measurements of vector meson photoproduction in the incoherent region provide a unique opportunity to extract the yet unmeasured total cross section for longitudinally polarized mesons σL=σ (VLN ) . The predictions for the latter strongly depend on the theoretical approaches. This work is stimulated by the construction of the new experiment GlueX at Jefferson Lab, designed to study the photoproduction of mesons in the beam energy range between 5 and 12 GeV.
Photoproduction of ω mesons off nuclei and impact of polarization on the meson-nucleon interaction
Chudakov, Eugene A.; Gevorkyan, Sergey; Somov, Alexander
2016-01-25
We consider photoproduction of ω mesons off complex nuclei to study interactions of transversely and longitudinally polarized vector mesons with nucleons. Whereas the total cross section for interactions of the transversely polarized vector mesons with nucleons σT = σ(VTN) can be obtained from coherent photoproduction, measurements of vector meson photoproduction in the incoherent region provide a unique opportunity to extract the not-yet-measured total cross section for longitudinally polarized mesons σL = σ(VLN). The predictions for the latter strongly depend on the theoretical approaches. Furthermore, this work is stimulated by the construction of the new experiment GlueX at Jefferson Lab, designedmore » to study the photoproduction of mesons in a large beam energy range up to 12 GeV.« less
Mesons and flavor on the conifold
Levi, Thomas S.; Ouyang, Peter
2007-11-15
We explore the addition of fundamental matter to the Klebanov-Witten field theory. We add probe D7-branes to the N=1 theory obtained from placing D3-branes at the tip of the conifold and compute the meson spectrum for the scalar mesons. In the UV limit of massless quarks we find the exact dimensions of the associated operators, which exhibit a simple scaling in the large-charge limit. For the case of massive quarks we compute the spectrum of scalar mesons numerically.
From the {psi} to charmed mesons
Goldhaber, G. |
1994-11-01
This talk deals with the author`s recollections about the discoveries of the J/{psi} the {psi}{prime} as well as psion spectroscopy and charmed mesons. He gives a chronology for the {psi} and {psi}{prime} discoveries. He also discusses the events which led to the charmed meson discovery as well as detailed discussions on the proof that the resonance observed in the K{sup {minus}} {pi}{sup +} system, at 1,865 MeV, was indeed the predicted charmed meson.
Charge asymmetry in charmed-meson photoproduction
Berezhnoy, A. V. Likhoded, A. K.
2006-01-15
Within the perturbative-recombination model, the charge asymmetries in the D*{sup +}-D*{sup -}, D*{sup 0}-D*{sup 0}, and D{sup +}{sub s}-D{sup -}{sub s} yields are estimated under the kinematical conditions of the COMPASS experiment. Corrections that arise owing to the mass of a light quark in a charmed meson are taken into account. The yield of D{sup +}{sub s} mesons is predicted to be large in relation to the yield of D{sup -}{sub s} mesons.
Hard Exclusive Vector Meson Leptoproduction At HERMES
Golembiovskaya, M.
2011-07-15
The HERMES experiment at DESY, Hamburg collected a set of data on hard exclusive vector meson ({rho}{sup 0}{phi},{omega}) leptoproduction using the 27.6 GeV longitudinally polarized lepton beam of HERA accelerator and longitudinally or transversely polarized or unpolarized gas targets. Measurements of exclusive vector meson production provide access to the structure of the nucleon since the process can be described in terms of Generalized Parton Distributions (GPDs). An overview of the HERMES results on exclusive vector mesons production is presented.
Baby Skyrmions stabilized by vector mesons
Foster, David; Sutcliffe, Paul
2009-06-15
Recent results suggest that multi-Skyrmions stabilized by {omega} mesons have very similar properties to those stabilized by the Skyrme term. In this paper we present the results of a detailed numerical investigation of a (2+1)-dimensional analogue of this situation. Namely, we compute solitons in an O(3) {sigma} model coupled to a massive vector meson and compare the results to baby Skyrmions, which are solitons in an O(3) {sigma} model including a Skyrme term. We find that multisolitons in the vector meson model are surprisingly similar to those in the baby Skyrme model, and we explain this correspondence using a simple derivative expansion.
A search for ϕ meson nucleus bound state using antiproton annihilation on nucleus
NASA Astrophysics Data System (ADS)
Ohnishi, H.; Bühler, P.; Cargnelli, M.; Curceanu, C.; Guaraldo, C.; Hartmann, O.; Hicks, K.; Iwasaki, M.; Ishiwatari, T.; Kienle, P.; Marton, J.; Muto, R.; Naruki, M.; Niiyama, M.; Noumi, H.; Okada, S.; Vidal, A. Romero; Sakaguchi, A.; Sakuma, F.; Sawada, S.; Sirghi, D.; Sirghi, F.; Suzuki, K.; Tsukada, K.; Doce, O. Vazquez; Widmann, E.; Yokkaichi, S.; Zmeskal, J.
The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. In 2007, KEK-PS E325 experiment reported about 3.4 % mass reduction of the ϕ meson in medium-heavy nuclei (Cu). This result is possibly one of the indications of the partial restoration of chiral symmetry in nuclei, however, unfortunately it is hard to make strong conclusions from the data. One of the ways to conclude the strength of the ϕ meson mass shift in nuclei will be by trying to produce only slowly moving ϕ mesons where the maximum nuclear matter effect can be probed. The observed mass reduction of the ϕ meson in the nucleus can be translated as the existence of an attractive force between ϕ meson and nucleus. Thus, one of the extreme conditions that can be achieved in the laboratory is indeed the formation of a ϕ-nucleus bound state, where the ϕ meson is "trapped" in the nucleus. The purpose of the experiment is to search for a ϕ-nucleus bound state and measure the binding energy of the system. We will demonstrate that a completely background-free missing-mass spectrum can be obtained efficiently by (bar{p}, φ) spectroscopy together with K + Λ tagging, using the primary reaction channel bar{p} p rightarrow φ φ. This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort.
A search for ϕ meson nucleus bound state using antiproton annihilation on nucleus
NASA Astrophysics Data System (ADS)
Ohnishi, H.; Bühler, P.; Cargnelli, M.; Curceanu, C.; Guaraldo, C.; Hartmann, O.; Hicks, K.; Iwasaki, M.; Ishiwatari, T.; Kienle, P.; Marton, J.; Muto, R.; Naruki, M.; Niiyama, M.; Noumi, H.; Okada, S.; Vidal, A. Romero; Sakaguchi, A.; Sakuma, F.; Sawada, S.; Sirghi, D.; Sirghi, F.; Suzuki, K.; Tsukada, K.; Doce, O. Vazquez; Widmann, E.; Yokkaichi, S.; Zmeskal, J.
2012-12-01
The mass shift of the vector mesons in nuclei is known to be a powerful tool for investigating the mechanism of generating hadron mass from the QCD vacuum. The mechanism is known to be the spontaneous breaking of chiral symmetry. In 2007, KEK-PS E325 experiment reported about 3.4 % mass reduction of the ϕ meson in medium-heavy nuclei (Cu). This result is possibly one of the indications of the partial restoration of chiral symmetry in nuclei, however, unfortunately it is hard to make strong conclusions from the data. One of the ways to conclude the strength of the ϕ meson mass shift in nuclei will be by trying to produce only slowly moving ϕ mesons where the maximum nuclear matter effect can be probed. The observed mass reduction of the ϕ meson in the nucleus can be translated as the existence of an attractive force between ϕ meson and nucleus. Thus, one of the extreme conditions that can be achieved in the laboratory is indeed the formation of a ϕ-nucleus bound state, where the ϕ meson is "trapped" in the nucleus. The purpose of the experiment is to search for a ϕ-nucleus bound state and measure the binding energy of the system. We will demonstrate that a completely background-free missing-mass spectrum can be obtained efficiently by (bar{p}, φ) spectroscopy together with K + Λ tagging, using the primary reaction channel bar{p} p rightarrow φ φ. This paper gives an overview of the physics motivation and the detector concept, and explains the direction of the initial research and development effort.
Tetraquarks in the 1 /N expansion and meson-meson resonances
NASA Astrophysics Data System (ADS)
Maiani, L.; Polosa, A. D.; Riquer, V.
2016-06-01
Diquarks are found to have the right degrees of freedom to describe the tetraquark poles in hidden-charm to open-charm meson-meson amplitudes. Compact tetraquarks result as intermediate states in non-planar diagrams of the 1 /N expansion and the corresponding resonances are narrower than what estimated before. The proximity of tetraquarks to meson-thresholds has an apparent role in this analysis and, in the language of meson molecules, an halving rule in the counting of states is obtained.
Studies on η meson production in dp collisions at the ANKE spectrometer
NASA Astrophysics Data System (ADS)
Fritzsch, Christopher; Guderian, Daniel; Khoukaz, Alfons; Mielke, Malte; Papenbrock, Michael; Schröer, Daniel
2016-03-01
Current investigations at the internal fixed target experiment ANKE at the storage ring COSY, located at the Forschungszentrum Jülich in Germany, focus on the behaviour of the η meson production process as well as on the study of angular distributions in the reactions d + p → 3He+ η and p+d → d + η + psp. The recent analysis status for both reactions will be presented and discussed.
Study of in-medium {omega}-meson properties in Ap and pA collisions
Kiselev, Yu. T. Kiselev, S. M.; Chumakov, M. M.
2010-01-15
The possibility to investigate the in-medium properties of the vector {omega} mesons at normal nuclear density is considered. The folding model and simulations with the RQMD generator have been used for studying of the {omega}-resonance production in Ap and pA reactions and its {omega} {sup {yields} {pi}0{gamma}} {sup {yields}}3{gamma} decay. We show that measurements in the inverse Ap kinematics is an effective way to get information about the {omega}-meson mass modification especially in not yet explored range of small meson momenta relative to the projectile nuclei where the strength of the effect is expected to be most strong. The traditional pA kinematics appears to be more preferable for the investigation of the in-medium {omega}-meson width. Using of compact electromagnetic calorimeter provides the possibility to collect large statistics and study the momentum dependencies of both the {omega}-meson mass and width at the density of normal nuclei.
Electroproduction of the {phi}(1020) Vector Meson at 4 GeV
Konstantin Loukachine
2000-02-01
We studied the reaction ep {yields} e{prime}p{prime}{phi} with a 4.2 GeV incident electron beam in the region of the electroproduction variables Q{sup 2} from 0.7 to 2.2 GeV{sup 2} and W from 2.0 to 2.6 GeV. The data were taken and analyzed at the Thomas Jefferson National Accelerator Facility. For the first time, we observe the expected t-slope dependence on Q{sup 2} and {Delta}{tau} in {phi} vector meson production. We find that the width of the forward {phi}-meson diffraction peak increases rapidly as the interaction time decreases below c{Delta}{tau} of 1 fm. Within a simple optical model framework, the data show that {phi} meson has a smaller size than the {rho}. The measured {phi} cross-section dependence on Q{sup 2} is in a good agreement with previous measurements and well-described by the phenomenological Pomeron exchange model. Our cross-section data do not favor the standard Vector Meson Dominance and s{bar s}-knockout model predictions. From the angular distribution of the decay {phi} {yields} K{sup +} K{sup -}, assuming the s-channel helicity conservation, we extracted the longitudinal-to-transverse cross-section ratio, R, and Vector Meson Dominance scaling parameter, {xi}{sup 2}, which are consistent with the previous measurements and the model expectations.
Meson production in photon and neutrino experiments
Shimony, J.S.
1988-01-01
The reaction {gamma}p {yields} {rho}{sup 0}{sub fast}p{pi}{sup +}{pi}{sup {minus}} has been studied with the linearly polarized 20 GeV monochromatic photon beam at the SLAC Hybrid Facility, to test the prediction of s channel helicity conservation in inelastic diffraction for t{prime} < 0.4 (GeV/c){sup 2}. In a sample of 1934 events from this reaction, the {rho}{sup 0} decay angular distributions and spin density matrix elements are consistent with s channel helicity conservation. The {pi}{sup +}{pi}{sup {minus}} mass shape displays the same skewing as seen in the reaction {gamma}p {yields} p{pi}{sup +}{pi}{sup {minus}}, and the p{pi}{sup +}{pi}{sup {minus}} mass distribution compares well and scale according to the vector dominance model with that produced in {pi}{sup {plus minus}}p {yields} p{pi}{sup +}{pi}{sup {minus}}. Coherent production of the a{sub 1} meson has been observed through the reaction {nu}Fr {yields} {mu}{sup {minus}}a{sub 1}{sup +}Fr in the Tohoku 1m freon bubble chamber hybrid system. The bubble chamber was exposed to the Fermilab wideband neutrino beam, generated by 800 GeV protons at the Tevatron. The observed rate from the final charged current sample of 1792 events was 1.1 {plus minus} 0.47%, and the a{sub 1} - W coupling is calculated to be f{sup 2}{sub a}/f{sup 2}{sub {rho}} = 5.2 {plus minus} 2.2. A comparison of the cross section and the kinematical parameters with the theoretical predictions of the vector dominance model, gives reasonable agreement with the data. A Monte-Carlo study was performed to check the possibility of detecting the radiative decay of the D*{sub s} in our bubble chamber. Using the most favorable predicted rate through the {phi} branching ratio, it was determined that three times our data sample would be needed for a one {sigma} effect above background.
NASA Astrophysics Data System (ADS)
Gubler, Philipp; Hattori, Koichi; Lee, Su Houng; Oka, Makoto; Ozaki, Sho; Suzuki, Kei
2016-03-01
We investigate the mass spectra of open heavy flavor mesons in an external constant magnetic field within QCD sum rules. Spectral Ansätze on the phenomenological side are proposed in order to properly take into account mixing effects between the pseudoscalar and vector channels, and the Landau levels of charged mesons. The operator product expansion is implemented up to dimension-5 operators. As a result, we find for neutral D mesons a significant positive mass shift that goes beyond simple mixing effects. In contrast, charged D mesons are further subject to Landau level effects, which together with the mixing effects almost completely saturate the mass shifts obtained in our sum rule analysis.
Recent progress on light scalar mesons
Peláez, J. R.
2014-07-23
This is a brief account of the recent developments on the determination of the mass and widths of the much debated scalar mesons, paying particular attention to the causes of major revision of the σ or f{sub 0}(500) meson in the last edition of the Review of Particle Physics, which has finally acknowledged that the situation concerning the mass and width of this controversial state has been settled, although this was already well-known to scalar meson practitioners for about a decade. I will briefly comment on the dispersive approach, followed by several groups, which seems to have been the most decisive in support of the existence and precise determinations of scalar meson properties.
Meson wave function from holographic approaches
Vega, Alfredo; Schmidt, Ivan; Branz, Tanja; Gutsche, Thomas; Lyubovitskij, Valery E.
2010-08-04
We discuss the light-front wave function for the valence quark state of mesons using the AdS/CFT correspondence. We consider two kinds of wave functions obtained in different holographic Soft-Wall approaches.
Gubler, Philipp; Hattori, Koichi; Lee, Su Houng; Oka, Makoto; Ozaki, Sho; Suzuki, Kei
2016-03-15
In this paper, we investigate the mass spectra of open heavy flavor mesons in an external constant magnetic field within QCD sum rules. Spectral Ansatze on the phenomenological side are proposed in order to properly take into account mixing effects between the pseudoscalar and vector channels, and the Landau levels of charged mesons. The operator product expansion is implemented up to dimension-5 operators. As a result, we find for neutral D mesons a significant positive mass shift that goes beyond simple mixing effects. In contrast, charged D mesons are further subject to Landau level effects, which together with the mixingmore » effects almost completely saturate the mass shifts obtained in our sum rule analysis.« less
Formation of mesic nuclei by (γ,p) reactions
NASA Astrophysics Data System (ADS)
Nagahiro, H.; Jido, D.; Hirenzaki, S.
2005-10-01
We present a theoretical study on formation rates of η and ω meson-nucleus systems induced by (γ,p) reactions on nuclear targets at ideal recoilless condition. We find that the smaller distortion effect in the (γ,p) reaction enables us to investigate properties of the mesons created deeply inside nucleus more clearly. We also consider excitation of scalar-isoscalar (σ) mode in nucleus in order to investigate spectral enhancement around two-pion threshold caused by partial restoration of chiral symmetry. We conclude that valuable information of meson-nucleus interactions can be extracted from global structure of the missing mass spectra in the (γ,p) reaction.
Rare meson decays into very light neutralinos
O'Leary, Ben
2010-02-10
Results are presented for the two-body decays of mesons into light neutralinos and from the first complete calculation of the loop-induced decays of kaons to pions plus light neutralinos and of B mesons to kaons plus light neutralinos. The branching ratios are shown to be strongly suppressed within the MSSM with minimal flavor violation, and no bounds on the neutralino mass can be inferred from experimental data, i.e. a massless neutralino is allowed.
Strangeness in the Meson Cloud Model
Signal, A. I.
2010-07-27
I review progress in calculating strange quark and antiquark distributions of the nucleon using the meson cloud model. This progress parallels that of the meson cloud model, which is now a useful theoretical basis for understanding symmetry breaking in nucleon parton distribution functions. I examine the breaking of symmetries involving strange quarks and antiquarks, including quark--antiquark symmetry in the sea, SU(3) flavour symmetry and SU(6) spin-flavour symmetry.
Meson and Baryon Spectroscopy on the Lattice
Richards, D. G.
2010-12-28
Recent progress at understanding the excited state spectrum of mesons and baryons is described. I begin by outlining the application of the variational method to compute the spectrum, and the program of anisotropic clover lattice generation designed for hadron spectroscopy. I present results for the excited meson spectrum, with continuum quantum numbers of the states clearly delineated. I conclude with recent results for the low lying baryon spectrum, and the prospects for future calculations.
Meson and baryon spectroscopy on the lattice
David Richards
2010-12-01
Recent progress at understanding the excited state spectrum of mesons and baryons is described. I begin by outlining the application of the variational method to compute the spectrum, and the program of anisotropic clover lattice generation designed for hadron spectroscopy. I present results for the excited meson spectrum, with continuum quantum numbers of the states clearly delineated. I conclude with recent results for the low lying baryon spectrum, and the prospects for future calculations.
Exotic Meson Results from BNL E852
NASA Astrophysics Data System (ADS)
Manak, Joseph J.
1998-10-01
Results from BNL experiment 852 on exotic (non-q\\overlineq) meson production are presented. Production of final states with J^PC = 1^-+ is observed in π^-p interactions at 18 GeV/c in the ηπ^-, ρπ^- and η^'π^- channels. Since such states are manifestly exotic if they are resonant, we describe amplitude analyses which use the interference between these states and other well known states to measure the phase behavior of the J^PC = 1^-+ amplitudes. The analyses show that, in addition to the previously reported(D.R. Thompson et al.), Phys. Rev. Lett. 79, 1630 (1997) evidence for an exotic meson in the ηπ^- channel, there is strong evidence for a second exotic meson decaying to ρπ^- with a mass of M=1593 ±8^+29_-47 MeV/c^2 and a width of Γ=168 ±20^+150_-12 MeV/c^2. We also show that the η^'π^- system is dominated by J^PC = 1^-+ production and we use those data to determine decay branching ratios for the exotic mesons. Such measurements are expected to be crucial in determining the constituent nature of the exotic mesons - that is, whether they are consistent with being hybrid mesons or four-quark states.
Branching ratios of B{sub c} meson decays into tensor meson in the final state
Sharma, Neelesh
2010-01-01
Two-body hadronic weak decays of B{sub c} meson involving tensor meson in the final state are studied by using the Isgur-Scora-Grinstein-Wise II model. Decay amplitudes are obtained using the factorization scheme in the spectator quark model. Branching ratios for the charm changing and bottom changing decay modes are predicted.
Photoproduction and Decay of Light Mesons in CLAS
Amaryan, Moskov Jamalovich
2013-08-01
We present preliminary experimental results on photoproduction and decay of light mesons measured with CLAS setup at JLAB . This include Dalitz decay of pseudoscalar and vector mesons, radiative decay of pseudoscalar mesons as well hadronic decays of pseudoscalar and vector mesons. The collected high statistics in some of decay channels exceeds the world data by an order of magnitude and some other decay modes are observed for the first time. It is shown how the CLAS data will improve the world data on transition form factors of light mesons, Dalitz plot analyses, branching ratios of rare decay modes and other fundamental properties potentially accessible through the light meson decays.
Scalar meson spectroscopy with lattice staggered fermions
Bernard, Claude; DeTar, Carleton; Fu Ziwen; Prelovsek, Sasa
2007-11-01
With sufficiently light up and down quarks the isovector (a{sub 0}) and isosinglet (f{sub 0}) scalar meson propagators are dominated at large distance by two-meson states. In the staggered-fermion formulation of lattice quantum chromodynamics, taste-symmetry breaking causes a proliferation of two-meson states that further complicates the analysis of these channels. Many of them are unphysical artifacts of the lattice approximation. They are expected to disappear in the continuum limit. The staggered-fermion fourth-root procedure has its purported counterpart in rooted staggered chiral perturbation theory (rS{chi}PT). Fortunately, the rooted theory provides a strict framework that permits the analysis of scalar meson correlators in terms of only a small number of low-energy couplings. Thus the analysis of the point-to-point scalar meson correlators in this context gives a useful consistency check of the fourth-root procedure and its proposed chiral realization. Through numerical simulation we have measured correlators for both the a{sub 0} and f{sub 0} channels in the 'Asqtad' improved staggered-fermion formulation in a lattice ensemble with lattice spacing a=0.12 fm. We analyze those correlators in the context of rS{chi}PT and obtain values of the low-energy chiral couplings that are reasonably consistent with previous determinations.
B meson decays to charmless meson pairs containing η or η' mesons
NASA Astrophysics Data System (ADS)
Aubert, B.; Karyotakis, Y.; Lees, J. P.; Poireau, V.; Prencipe, E.; Prudent, X.; Tisserand, V.; Garra Tico, J.; Grauges, E.; Martinelli, M.; Palano, A.; Pappagallo, M.; Eigen, G.; Stugu, B.; Sun, L.; Battaglia, M.; Brown, D. N.; Kerth, L. T.; Kolomensky, Yu. G.; Lynch, G.; Osipenkov, I. L.; Tackmann, K.; Tanabe, T.; Hawkes, C. M.; Soni, N.; Watson, A. T.; Koch, H.; Schroeder, T.; Asgeirsson, D. J.; Fulsom, B. G.; Hearty, C.; Mattison, T. S.; McKenna, J. A.; Barrett, M.; Khan, A.; Randle-Conde, A.; Blinov, V. E.; Bukin, A. D.; Buzykaev, A. R.; Druzhinin, V. P.; Golubev, V. B.; Onuchin, A. P.; Serednyakov, S. I.; Skovpen, Yu. I.; Solodov, E. P.; Todyshev, K. Yu.; Bondioli, M.; Curry, S.; Eschrich, I.; Kirkby, D.; Lankford, A. J.; Lund, P.; Mandelkern, M.; Martin, E. C.; Stoker, D. P.; Atmacan, H.; Gary, J. W.; Liu, F.; Long, O.; Vitug, G. M.; Yasin, Z.; Sharma, V.; Campagnari, C.; Hong, T. M.; Kovalskyi, D.; Mazur, M. A.; Richman, J. D.; Beck, T. W.; Eisner, A. M.; Heusch, C. A.; Kroseberg, J.; Lockman, W. S.; Martinez, A. J.; Schalk, T.; Schumm, B. A.; Seiden, A.; Wang, L.; Winstrom, L. O.; Cheng, C. H.; Doll, D. A.; Echenard, B.; Fang, F.; Hitlin, D. G.; Narsky, I.; Ongmongkolkul, P.; Piatenko, T.; Porter, F. C.; Andreassen, R.; Mancinelli, G.; Meadows, B. T.; Mishra, K.; Sokoloff, M. D.; Bloom, P. C.; Ford, W. T.; Gaz, A.; Hirschauer, J. F.; Nagel, M.; Nauenberg, U.; Smith, J. G.; Wagner, S. R.; Ayad, R.; Toki, W. H.; Wilson, R. J.; Feltresi, E.; Hauke, A.; Jasper, H.; Karbach, T. M.; Merkel, J.; Petzold, A.; Spaan, B.; Wacker, K.; Kobel, M. J.; Nogowski, R.; Schubert, K. R.; Schwierz, R.; Bernard, D.; Latour, E.; Verderi, M.; Clark, P. J.; Playfer, S.; Watson, J. E.; Andreotti, M.; Bettoni, D.; Bozzi, C.; Calabrese, R.; Cecchi, A.; Cibinetto, G.; Fioravanti, E.; Franchini, P.; Luppi, E.; Munerato, M.; Negrini, M.; Petrella, A.; Piemontese, L.; Santoro, V.; Baldini-Ferroli, R.; Calcaterra, A.; de Sangro, R.; Finocchiaro, G.; Pacetti, S.; Patteri, P.; Peruzzi, I. M.; Piccolo, M.; Rama, M.; Zallo, A.; Contri, R.; Guido, E.; Lo Vetere, M.; Monge, M. R.; Passaggio, S.; Patrignani, C.; Robutti, E.; Tosi, S.; Chaisanguanthum, K. S.; Morii, M.; Adametz, A.; Marks, J.; Schenk, S.; Uwer, U.; Bernlochner, F. U.; Klose, V.; Lacker, H. M.; Lueck, T.; Volk, A.; Bard, D. J.; Dauncey, P. D.; Tibbetts, M.; Behera, P. K.; Charles, M. J.; Mallik, U.; Cochran, J.; Crawley, H. B.; Dong, L.; Eyges, V.; Meyer, W. T.; Prell, S.; Rosenberg, E. I.; Rubin, A. E.; Gao, Y. Y.; Gritsan, A. V.; Guo, Z. J.; Arnaud, N.; Béquilleux, J.; D'Orazio, A.; Davier, M.; Derkach, D.; da Costa, J. Firmino; Grosdidier, G.; Le Diberder, F.; Lepeltier, V.; Lutz, A. M.; Malaescu, B.; Pruvot, S.; Roudeau, P.; Schune, M. H.; Serrano, J.; Sordini, V.; Stocchi, A.; Wormser, G.; Lange, D. J.; Wright, D. M.; Bingham, I.; Burke, J. P.; Chavez, C. A.; Fry, J. R.; Gabathuler, E.; Gamet, R.; Hutchcroft, D. E.; Payne, D. J.; Touramanis, C.; Bevan, A. J.; Clarke, C. K.; di Lodovico, F.; Sacco, R.; Sigamani, M.; Cowan, G.; Paramesvaran, S.; Wren, A. C.; Brown, D. N.; Davis, C. L.; Denig, A. G.; Fritsch, M.; Gradl, W.; Hafner, A.; Alwyn, K. E.; Bailey, D.; Barlow, R. J.; Jackson, G.; Lafferty, G. D.; West, T. J.; Yi, J. I.; Anderson, J.; Chen, C.; Jawahery, A.; Roberts, D. A.; Simi, G.; Tuggle, J. M.; Dallapiccola, C.; Salvati, E.; Cowan, R.; Dujmic, D.; Fisher, P. H.; Henderson, S. W.; Sciolla, G.; Spitznagel, M.; Yamamoto, R. K.; Zhao, M.; Patel, P. M.; Robertson, S. H.; Schram, M.; Biassoni, P.; Lazzaro, A.; Lombardo, V.; Palombo, F.; Stracka, S.; Cremaldi, L.; Godang, R.; Kroeger, R.; Sonnek, P.; Summers, D. J.; Zhao, H. W.; Simard, M.; Taras, P.; Nicholson, H.; de Nardo, G.; Lista, L.; Monorchio, D.; Onorato, G.; Sciacca, C.; Raven, G.; Snoek, H. L.; Jessop, C. P.; Knoepfel, K. J.; Losecco, J. M.; Wang, W. F.; Corwin, L. A.; Honscheid, K.; Kagan, H.; Kass, R.; Morris, J. P.; Rahimi, A. M.; Sekula, S. J.; Wong, Q. K.; Blount, N. L.; Brau, J.; Frey, R.; Igonkina, O.; Kolb, J. A.; Lu, M.; Rahmat, R.; Sinev, N. B.; Strom, D.; Strube, J.; Torrence, E.; Castelli, G.; Gagliardi, N.; Margoni, M.; Morandin, M.; Posocco, M.; Rotondo, M.; Simonetto, F.; Stroili, R.; Voci, C.; Del Amo Sanchez, P.; Ben-Haim, E.; Bonneaud, G. R.; Briand, H.; Chauveau, J.; Hamon, O.; Leruste, Ph.; Marchiori, G.; Ocariz, J.; Perez, A.; Prendki, J.; Sitt, S.; Gladney, L.; Biasini, M.; Manoni, E.; Angelini, C.; Batignani, G.; Bettarini, S.; Calderini, G.; Carpinelli, M.; Cervelli, A.; Forti, F.; Giorgi, M. A.; Lusiani, A.; Morganti, M.; Neri, N.; Paoloni, E.; Rizzo, G.; Walsh, J. J.; Lopes Pegna, D.; Lu, C.; Olsen, J.; Smith, A. J. S.; Telnov, A. V.; Anulli, F.; Baracchini, E.; Cavoto, G.; Faccini, R.; Ferrarotto, F.; Ferroni, F.; Gaspero, M.; Jackson, P. D.; Li Gioi, L.; Mazzoni, M. A.; Morganti, S.; Piredda, G.; Renga, F.; Voena, C.; Ebert, M.; Hartmann, T.; Schröder, H.; Waldi, R.; Adye, T.; Franek, B.; Olaiya, E. O.; Wilson, F. F.; Emery, S.; Esteve, L.; Hamel de Monchenault, G.; Kozanecki, W.; Vasseur, G.; Yèche, Ch.; Zito, M.; Allen, M. T.; Aston, D.; Bartoldus, R.; Benitez, J. F.; Cenci, R.; Coleman, J. P.; Convery, M. R.; Dingfelder, J. C.; Dorfan, J.; Dubois-Felsmann, G. P.; Dunwoodie, W.; Field, R. C.; Franco Sevilla, M.; Gabareen, A. M.; Graham, M. T.; Grenier, P.; Hast, C.; Innes, W. R.; Kaminski, J.; Kelsey, M. H.; Kim, H.; Kim, P.; Kocian, M. L.; Leith, D. W. G. S.; Li, S.; Lindquist, B.; Luitz, S.; Luth, V.; Lynch, H. L.; Macfarlane, D. B.; Marsiske, H.; Messner, R.; Muller, D. R.; Neal, H.; Nelson, S.; O'Grady, C. P.; Ofte, I.; Perl, M.; Ratcliff, B. N.; Roodman, A.; Salnikov, A. A.; Schindler, R. H.; Schwiening, J.; Snyder, A.; Su, D.; Sullivan, M. K.; Suzuki, K.; Swain, S. K.; Thompson, J. M.; Va'Vra, J.; Wagner, A. P.; Weaver, M.; West, C. A.; Wisniewski, W. J.; Wittgen, M.; Wright, D. H.; Wulsin, H. W.; Yarritu, A. K.; Young, C. C.; Ziegler, V.; Chen, X. R.; Liu, H.; Park, W.; Purohit, M. V.; White, R. M.; Wilson, J. R.; Bellis, M.; Burchat, P. R.; Edwards, A. J.; Miyashita, T. S.; Ahmed, S.; Alam, M. S.; Ernst, J. A.; Pan, B.; Saeed, M. A.; Zain, S. B.; Soffer, A.; Spanier, S. M.; Wogsland, B. J.; Eckmann, R.; Ritchie, J. L.; Ruland, A. M.; Schilling, C. J.; Schwitters, R. F.; Wray, B. C.; Drummond, B. W.; Izen, J. M.; Lou, X. C.; Bianchi, F.; Gamba, D.; Pelliccioni, M.; Bomben, M.; Bosisio, L.; Cartaro, C.; Della Ricca, G.; Lanceri, L.; Vitale, L.; Azzolini, V.; Lopez-March, N.; Martinez-Vidal, F.; Milanes, D. A.; Oyanguren, A.; Albert, J.; Banerjee, Sw.; Bhuyan, B.; Choi, H. H. F.; Hamano, K.; King, G. J.; Kowalewski, R.; Lewczuk, M. J.; Nugent, I. M.; Roney, J. M.; Sobie, R. J.; Gershon, T. J.; Harrison, P. F.; Ilic, J.; Latham, T. E.; Mohanty, G. B.; Puccio, E. M. T.; Band, H. R.; Chen, X.; Dasu, S.; Flood, K. T.; Pan, Y.; Prepost, R.; Vuosalo, C. O.; Wu, S. L.
2009-12-01
We present updated measurements of the branching fractions for B0 meson decays to ηK0, ηη, ηϕ, ηω, η'K0, η'η', η'ϕ, and η'ω, and branching fractions and CP-violating charge asymmetries for B+ decays to ηπ+, ηK+, η'π+, and η'K+. The data represent the full data set of 467×106 BB¯ pairs collected with the BABAR detector at the PEP-II asymmetric-energy e+e- collider at the SLAC National Accelerator Laboratory. Besides large signals for the four charged B decay modes and for B0→η'K0, we find evidence for three B0 decay modes at greater than 3.0σ significance. We find B(B0→ηK0)=(1.15-0.38+0.43±0.09)×10-6, B(B0→ηω)=(0.94-0.30+0.35±0.09)×10-6, and B(B0→η'ω)=(1.01-0.38+0.46±0.09)×10-6, where the first (second) uncertainty is statistical (systematic). For the B+→ηK+ decay mode, we measure the charge asymmetry Ach(B+→ηK+)=-0.36±0.11±0.03.
Review of meson spectroscopy: quark states and glueballs
Chanowitz, M.S.
1981-11-01
A group of three lectures on hadron spectroscopy are presented. Topics covered include: light L = 0 mesons, light L = 1 mesons, antiquark antiquark quark quark exotics, a catalogue of higher quark antiquark excitations, heavy quarkonium, and glueballs. (GHT)
Vector meson modification in nuclear matter at CLAS
Djalali, Chaden; Wood, Michael; Nasseripour, Rakhsha; Weygand, Dennis
2008-09-01
Photoproduction of vector mesons off nuclei were performed at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). The properties of the A vector mesons were investigated via their rare leptonic decay to e+e . After subtracting the combinatorial background, the A meson mass distributions were extracted for each of the targets. We observe no effects on the mass of the A meson, some widening in titanium and iron is observed consistent with the collisional broadening.
Nucleon Resonance Electrocouplings from the CLAS Meson Electroproduction Data.
Inna Aznauryan, Volker Burkert, Viktor Mokeev
2012-04-01
Transition helicity amplitudes {gamma}{sub {nu}}NN* (electrocouplings) were determined for prominent excited proton states with masses less than 1.8 GeV in independent analyses of major meson electroproduction channels: {pi}{sup +}n, {pi}{sup 0}p and {pi}{sup +}{pi}{sup -}p. Consistent results on resonance electrocouplings obtained from analyses of these exclusive reactions with very different non-resonant contributions demonstrated reliable extraction of these fundamental quantities for states that have significant decays for either N{pi} or N{pi}{pi} channels. Preliminary results on electrocouplings of N* states with masses above 1.6 GeV have become available from the CLAS data on {pi}{sup +}{pi}{sup -}p electroproduction off protons for the first time. Comparison with quark models and coupled channel approaches strongly suggest that N* structure is determined by contributions from an internal core of three constituent quarks and an external meson-baryon cloud at the distance scales covered in measurements with the CLAS detector.
Charmed-strange meson spectrum: Old and new problems
NASA Astrophysics Data System (ADS)
Segovia, Jorge; Entem, David R.; Fernández, Francisco
2015-05-01
The LHCb Collaboration has recently reported the observation for the first time of a spin-3 resonance in the heavy quark sector. They have shown that the D¯0K- structure seen in the Bs0→D¯0K-π+ reaction and with invariant mass 2.86 GeV is an admixture of a spin-1 and a spin-3 resonance. Motivated by the good agreement between our theoretical predictions some time ago and the properties extracted from the experiment of the Ds1 *(2860 ) and Ds3 *(2860 ) states, we perform an extension of the study of the strong decay properties of the DsJ *(2860 ) and present the same analysis for the Ds1 *(2700 ) and Ds J(3040 ) mesons. This provides a unified and simultaneous description of the three higher excited charmed-strange resonances observed until now. For completeness, we present theoretical results for masses and strong decays of the low-lying charmed-strange mesons and those experimental missing states which belong to the spin multiplets of the discovered Ds1 *(2700 ), DsJ *(2860 ) and Ds J(3040 ) resonances. The theoretical framework used is a constituent quark model which successfully describes hadron phenomenology from light to heavy quark sectors.
Dynamical coupled channels calculation of pion and omega meson production
Paris, Mark W.
2009-02-15
The dynamical coupled-channels approach developed at the Excited Baryon Analysis Center is extended to include the {omega}N channel to study {pi}- and {omega}-meson production induced by scattering pions and photons from the proton. Six intermediate channels, including {pi}N, {eta}N, {pi}{delta}, {sigma}N, {rho}N, and {omega}N, are employed to describe unpolarized and polarized data. Bare parameters in an effective hadronic Lagrangian are determined in a fit to the data for {pi}N{yields}{pi}N, {gamma}N{yields}{pi}N, {pi}{sup -}p{yields}{omega}n, and {gamma}p{yields}{omega}p reactions at center-of-mass energies from threshold to W<2.0 GeV. The T matrix determined in these fits is used to calculate the photon beam asymmetry for {omega}-meson production and the {omega}N{yields}{omega}N total cross section and {omega}N-scattering lengths. The calculated beam asymmetry is in good agreement with the observed in the range of energies near threshold to W < or approx. 2.0 GeV.
Electroproduction of baryon-meson states and strangeness suppression
NASA Astrophysics Data System (ADS)
Santopinto, E.; García-Tecocoatzi, H.; Bijker, R.
2016-08-01
We describe the electroproduction ratios of baryon-meson states from nucleon, inferring from the sea quarks in the nucleon using an extension of the quark model that takes into account the sea. As a result we provide, with no adjustable parameters, the predictions of ratios of exclusive meson-baryon final states: ΛK+, Σ* K, ΣK, pπ0, and nπ+. These predictions are in agreement with the new JLab experimental data showing that sea quarks play an important role in the electroproduction. We also predicted further ratios of exclusive reactions that can be measured and tested in future experiments. In particular, we suggested new experiments on deuterium and tritium. Such measurements can provide crucial tests of different predictions concerning the structure of nucleon and its sea quarks helping to solve an outstanding problem. Finally, we compute the so called strangeness suppression factor, λs, that is the suppression of strange quark-antiquark pairs compared to nonstrange pairs, and we found that our finding with this simple extension of the quark model is in good agreement with the results of JLab and CERN experiments.
Unitary coupled-channels model for three-mesons decays of heavy mesons
Hiroyuki Kamano; Nakamura, Satoshi X.; Lee, Tsung-Shung H.; Sato, Toru
2011-12-16
In this study, a unitary coupled-channels model is presented for investigating the decays of heavy mesons and excited meson states into three light pseudoscalar mesons. The model accounts for the three-mesons final state interactions in the decay processes, as required by both the three-body and two-body unitarity conditions. In the absence of the Z-diagram mechanisms that are necessary consequences of the three-body unitarity, our decay amplitudes are reduced to a form similar to those used in the so-called isobar-model analysis. We apply our coupled-channels model to the three-pions decays of α_{1}(1260), π_{2}(1670), π_{2}(2100), and D^{0} mesons, and show that the Z-diagram mechanisms can contribute to the calculated Dalitz plot distributions by as much as 30% in magnitudes in the regions where f_{0}(600), ρ(770), and f_{2}(1270) dominate the distributions. Also, by fitting to the same Dalitz plot distributions, we demonstrate that the decay amplitudes obtained with the unitary model and the isobar model can be rather different, particularly in the phase that plays a crucial role in extracting the CKM CP-violating phase from the data of B meson decays. Our results indicate that the commonly used isobar model analysis must be extended to account for the final state interactions required by the three-body unitarity to reanalyze the three-mesons decays of heavy mesons, thereby exploring hybrid or exotic mesons, and signatures of physics beyond the standard model.
Unitary coupled-channels model for three-mesons decays of heavy mesons
Hiroyuki Kamano; Nakamura, Satoshi X.; Lee, Tsung-Shung H.; Sato, Toru
2011-12-16
In this study, a unitary coupled-channels model is presented for investigating the decays of heavy mesons and excited meson states into three light pseudoscalar mesons. The model accounts for the three-mesons final state interactions in the decay processes, as required by both the three-body and two-body unitarity conditions. In the absence of the Z-diagram mechanisms that are necessary consequences of the three-body unitarity, our decay amplitudes are reduced to a form similar to those used in the so-called isobar-model analysis. We apply our coupled-channels model to the three-pions decays of α1(1260), π2(1670), π2(2100), and D0 mesons, and show that themore » Z-diagram mechanisms can contribute to the calculated Dalitz plot distributions by as much as 30% in magnitudes in the regions where f0(600), ρ(770), and f2(1270) dominate the distributions. Also, by fitting to the same Dalitz plot distributions, we demonstrate that the decay amplitudes obtained with the unitary model and the isobar model can be rather different, particularly in the phase that plays a crucial role in extracting the CKM CP-violating phase from the data of B meson decays. Our results indicate that the commonly used isobar model analysis must be extended to account for the final state interactions required by the three-body unitarity to reanalyze the three-mesons decays of heavy mesons, thereby exploring hybrid or exotic mesons, and signatures of physics beyond the standard model.« less
Magnetic properties of ground-state mesons
NASA Astrophysics Data System (ADS)
Šimonis, V.
2016-04-01
Starting with the bag model a method for the study of the magnetic properties (magnetic moments, magnetic dipole transition widths) of ground-state mesons is developed. We calculate the M1 transition moments and use them subsequently to estimate the corresponding decay widths. These are compared with experimental data, where available, and with the results obtained in other approaches. Finally, we give the predictions for the static magnetic moments of all ground-state vector mesons including those containing heavy quarks. We have a good agreement with experimental data for the M1 decay rates of light as well as heavy mesons. Therefore, we expect our predictions for the static magnetic properties ( i.e., usual magnetic moments) to be of sufficiently high quality, too.
Lepton flavor violating decays of vector mesons
Gutsche, Thomas; Lyubovitskij, Valery E.; Helo, Juan C.; Kovalenko, Sergey
2010-02-01
We estimate the rates of lepton flavor violating decays of the vector mesons {rho}, {omega}, and {phi}{yields}e{mu}. The theoretical tools are based on an effective Lagrangian approach without referring to any specific realization of the physics beyond the standard model responsible for lepton flavor violation (Le{sub f}). The effective lepton-vector meson couplings are extracted from the existing experimental bounds on the nuclear {mu}{sup -}-e{sup -} conversion. In particular, we derive an upper limit for the Le{sub f} branching ratio Br({phi}{yields}e{mu}){<=}1.3x10{sup -21} which is much more stringent than the recent experimental result Br({phi}{yields}e{mu})<2x10{sup -6} presented by the SND Collaboration. Very tiny limits on Le{sub f} decays of vector mesons derived in this paper make direct experimental observation of these processes unrealistic.
Exclusive vector meson production at HERMES
NASA Astrophysics Data System (ADS)
Movsisyan, Aram
2014-06-01
Exclusive electroproduction of vector mesons has been measured on hydrogen and deuterium targets at HERMES using the 27.6 GeV electron/positron beam of HERA. From this process, more information can be obtained about generalized parton distributions (GPDs), which provide a unified description of the structure of hadrons embedding longitudinal-momentum distributions (ordinary PDFs) and transverse-position information (form factors). The study of the azimuthal distribution of the decay products via spin-density matrix elements provide constraints on helicity-amplitudes used to describe exclusive vector-meson production. Recent results from the HERMES experiment on the production of rho, omega and phi mesons will be presented.
Massive mesons in Weyl-Dirac theory
NASA Astrophysics Data System (ADS)
Mirabotalebi, S.; Ahmadi, F.; Salehi, H.
2008-01-01
In order to study the mass generation of the vector fields in the framework of a conformal invariant gravitational model, the Weyl-Dirac theory is considered. The mass of the Weyl’s meson fields plays a principal role in this theory, it connects basically the conformal and gauge symmetries. We estimate this mass by using the large-scale characteristics of the observed universe. To do this we firstly specify a preferred conformal frame as a cosmological frame, then in this frame, we introduce an exact possible solution of the theory. We also study the dynamical effect of the massive vector meson fields on the trajectories of an elementary particle. We show that a local change of the cosmological frame leads to a Hamilton-Jacobi equation describing a particle with an adjustable mass. The dynamical effect of the massive vector meson field presents itself in the form of a correction term for the mass of the particle.
Photoproduction of scalar mesons at medium energies
Da Silva, M. L.; Machado, M. V.
2013-03-25
In this work we will focus on photoproduction of mesons states a{sub 0}(980), f{sub 0}(1500) and f{sub 0}(1710). The f{sub 0}(1500) and f{sub 0}(1710) mesons will be considered in distinct mixing possibilities and assuming that a{sub 0}(980) is member of the ground-state nonet. The theoretical formalism is the Regge approach with reggeized {rho} and {omega} exchange. The differential and integrated total cross section are computed for the cases of the mesons a{sub 0}(980), f{sub 0}(1500) and f{sub 0}(1710) focusing the GlueX energy regime with photon energy E = 9 GeV.
Inclusive meson production in 3.5 GeV pp collisions studied with the HADES spectrometer
Rustamov, Anar
2010-08-05
We present the inclusive di-electron invariant-mass spectrum from p+p interactions at 3.5 GeV kinetic beam energy. It is a very important reference for the study of vector meson production off the nucleus, recently investigated by HADES in p+{sup 93}Nb reactions at the same beam energy. Up to invariant masses of 0.6 GeV/c{sup 2} the main contributions to the e{sup +}e{sup -} spectrum are {pi}{sup 0},{eta}, {omega} and {Delta} Dalitz decays. In the vector-meson region a clear peak corresponding to the {omega} direct decay is reconstructed with {approx_equal}2% mass resolution. Subtracting this peak from the spectrum allows to investigate additional sources, in particular the {rho} meson. Indeed, the latest results from HSD and UrQMD calculations show different distributions for the shape of the {rho} meson at these energies. Therefore it is important to experimentally understand the production mechanism of the {rho} meson in elementary reactions. Besides the spectral shape of the mesons, their inclusive production cross sections are also not known at these energies. Due to the large and flat acceptance of the HADES spectrometer for e{sup +}e{sup -} masses above 0.2 GeV/c{sup 2} and for P{sub T}<1GeV/c, acceptance corrections are to a large extent model independent. This allows us to extract the preliminary inclusive cross section values for the meson productions at these energies.
Scalar mesons in a linear sigma model with (axial-)vector mesons
Parganlija, D.; Kovacs, P.; Wolf, Gy.; Giacosa, F.; Rischke, D. H.
2013-03-25
The structure of the scalar mesons has been a subject of debate for many decades. In this work we look for qq states among the physical resonances using an extended Linear Sigma Model that contains scalar, pseudoscalar, vector, and axial-vector mesons both in the non-strange and strange sectors. We perform global fits of meson masses, decay widths and amplitudes in order to ascertain whether the scalar qq states are below or above 1 GeV. We find the scalar states above 1 GeV to be preferred as qq states.
Light O++ Mesons: Scalargators in Florida
NASA Astrophysics Data System (ADS)
Pennington, M. R.
2010-08-01
Light scalar mesons abound in hadron processes, like the alligators in the Florida Everglades. Moreover, scalars are intimately tied to the vacuum structure of QCD. They are the product of many decays. Consequently, a rich source of recent information about them has come from experiments producing heavy flavour mesons. Indeed, scalars will continue to dominate many of the processes to be studied at forthcoming facilities like BESIII in Beijing, FAIR at GSI Darmstadt and the GlueX experiment at JLab, making an understanding (or at least an excellent and theoretically consistent description) essential for the physics missions of these facilities.
CP violation in B meson decays
NASA Astrophysics Data System (ADS)
Noguchi, S.; Belle Group
2003-06-01
CP violation in neutral B meson decays has been observed confirming the prediction of the Kobayashi-Maskawa model where introduction of six quaks naturally induces CP violation in the weak interaction. The measurements of CP asymmetryc in B meson decays were made at the newly constructed Asymmetric B factories, which consist of high luminosity, ebergy-asymmetric e+e- colliders (KEKB and PEP-II) and detectors (Belle and BaBar). The results are in good agreement and are consistent with other experimental results within the framework of the Standard Model.
Exotic nuclei with open heavy flavor mesons
Yasui, Shigehiro; Sudoh, Kazutaka
2009-08-01
We propose stable exotic nuclei bound with D and B mesons with respect to heavy quark symmetry. We indicate that an approximate degeneracy of D(B) and D*(B*) mesons plays an important role, and discuss the stability of DN and BN bound states. We find the binding energies 1.4 MeV and 9.4 MeV for each state in the J{sup P}=1/2{sup -} with the I=0 channel. We discuss also possible existence of exotic nuclei DNN and BNN.
Excited light isoscalar mesons from lattice QCD
Christopher Thomas
2011-07-01
I report a recent lattice QCD calculation of an excited spectrum of light isoscalar mesons, something that has up to now proved challenging for lattice QCD. With novel techniques we extract an extensive spectrum with high statistical precision, including spin-four states and, for the first time, light isoscalars with exotic quantum numbers. In addition, the hidden flavour content of these mesons is determined, providing a window on annihilation dynamics in QCD. I comment on future prospects including applications to the study of resonances.
Meson spectrum in strong magnetic fields
NASA Astrophysics Data System (ADS)
Andreichikov, M. A.; Kerbikov, B. O.; Orlovsky, V. D.; Simonov, Yu. A.
2013-05-01
We study the relativistic quark-antiquark system embedded in a magnetic field (MF). The Hamiltonian containing confinement, one gluon exchange, and spin-spin interaction is derived. We analytically follow the evolution of the lowest meson states as a function of MF strength. Calculating the one gluon exchange interaction energy ⟨VOGE⟩ and spin-spin contribution ⟨aSS⟩ we have observed that these corrections remain finite at large MF, preventing the vanishing of the total ρ meson mass at some Bcrit, as previously thought. We display the ρ masses as functions of the MF in comparison with recent lattice data.
Scalar mesons and polarizability of the nucleon
Schumacher, Martin
2008-08-31
It is shown that the scalar mesons {sigma}, f{sub 0}(980) and a{sub 0}(980) as t-channel exchanges quantitatively solve the problem of diamagnetism and give an explanation of the large missing part of the electric polarizability {alpha} showing up when only the pion cloud is taken into account. The electric polarizability of the proton {alpha}{sub p} confirms a two-photon width of the {sigma} meson of {gamma}{sub {sigma}}{sub {gamma}}{sub {gamma}} = (2.58{+-}0.26) keV.
Tensor mesons produced in tau lepton decays
Lopez Castro, G.; Munoz, J. H.
2011-05-01
Light tensor mesons (T=a{sub 2}, f{sub 2} and K{sub 2}*) can be produced in decays of {tau} leptons. In this paper we compute the branching ratios of {tau}{yields}T{pi}{nu} decays by assuming the dominance of intermediate virtual states to model the form factors involved in the relevant hadronic matrix elements. The exclusive f{sub 2}(1270){pi}{sup -} decay mode turns out to have the largest branching ratio, of O(10{sup -4}). Our results indicate that the contribution of tensor meson intermediate states to the three-pseudoscalar channels of {tau} decays are rather small.
Shape of mesons in holographic QCD
Torabian, Mahdi; Yee, Ho-Ung
2009-10-15
Based on the expectation that the constituent quark model may capture the right physics in the large N limit, we point out that the orbital angular momentum of the quark-antiquark pair inside light mesons of low spins in the constituent quark model may provide a clue for the holographic dual string model of large N QCD. Our discussion, relying on a few suggestive assumptions, leads to a necessity of world-sheet fermions in the bulk of dual strings that can incorporate intrinsic spins of fundamental QCD degrees of freedom. We also comment on the interesting issue of the size of mesons in holographic QCD.
NASA Astrophysics Data System (ADS)
Roy, P.
2016-05-01
Baryon spectroscopy is an indispensable tool for investigating the nature of strong interaction within baryons. The study of vector-meson photoproduction is expected to improve our understanding of the properties of known baryon resonances and also immensely aid in discovering new higher-mass resonances. Polarization observables, in addition to unpolarized cross sections, are required to identify the contributing resonances to these reactions with minimal ambiguities. Preliminary results from the FROST experiment on beam-polarization observables in γ →p →→p ω as well as γ →p →→p π+π- using a linearly-polarized beam and a transversely-polarized FROzen Spin butanol Target will be presented. The latter reaction will provide important information on N* to (broad) ρ vector-meson decay modes, which is difficult to extract directly from the data.
Sharma, Neelesh; Verma, R. C.; Dhir, Rohit
2011-01-01
In this paper, we investigate phenomenologically two-body weak decays of the bottom mesons emitting pseudoscalar/vector meson and a tensor meson. Form factors are obtained using the improved Isgur-Scora-Grinstein-Wise II model. Consequently, branching ratios for the Cabibbo-Kobayashi-Maskawa-favored and Cabibbo-Kobayashi-Maskawa-suppressed decays are calculated.
Issues in light meson spectroscopy: The case for meson spectroscopy at CEBAF
Godfrey, S.
1994-04-01
The author reviews some outstanding issues in meson spectroscopy. The most important qualitative issue is whether hadrons with explicit gluonic degrees of freedom exist. To answer this question requires a much better understanding of conventional q{bar q} mesons. The author therefore begins by examining the status of conventional meson spectroscopy and how the situation can be improved. The expected properties of gluonic excitations are discussed with particular emphasis on hybrids to give guidance to experimental searches. Multiquark systems are commented upon as they are likely to be important in the mass region under study and will have to be understood better. In the final section the author discusses the opportunities that CEBAF can offer for the study of meson spectroscopy.
K. Tsushima, P. A. M. Guichon, R. Shyam, A. W. Thomas
2010-12-01
We study the binding of hypernuclei based on the latest version of quark-meson coupling model, and estimate the phtoproduction cross sections for the {sup 12}C({gamma},K{sup +}){sub {Lambda}}{sup 12}B reaction using the bound {Lambda} spinors obtained in the model.
Polarization analysis of vector-meson production in pion-nucleon interactions
NASA Astrophysics Data System (ADS)
Arash, Firooz; Habibi, Mohammad F.
1993-07-01
In view of the growing (though still incomplete) set of data on vector-meson production in pion-nucleon interactions, the polarization structure of this reaction is presented, together with polarization tests of one-particle-exchange processes in the s and t channels, as well as polarization tests for the Skyrmion model. The amplitude-observable relations are exhibited in the helicity, transversity, and planar-transverse frames. The desirable direction of future experimental programs is also outlined.
Predictions of three-body-decays of mesons from pole-dominated dispersion relations
NASA Technical Reports Server (NTRS)
Thews, R. L.
1974-01-01
The investigation shows that the method of finite dispersion relations (FDR) as developed by Aviv and Nussinov (1970) is consistent with a wide range of three-body meson decays. The specific results vary with each reaction. For each possibility a definite form for the t-channel Regge-pole terms is selected. The results of the investigation indicate the basic reliability of an approach based on the FDR method and the finite-energy sum rules.
Vector meson production in ultra-peripheral collisions at the LHC
Fiore, R.; Jenkovszky, L.; Salii, A.; Libov, V.; Machado, M. V. T.
2015-04-10
By using a Regge-pole model for vector meson production (VMP), that successfully describes the HERA data, we analyse the connection of VMP cross sections in photon-induced reactions at HERA with those in ultra-peripheral collisions at the Large Hadron Collider (LHC). The role of the low-energy behaviour of VMP cross sections in γp collisions is scrutinized.
Probing Nucleon Structure with Meson Electro-production in Hall C
Wood, Stephen
2011-02-01
Meson electro-production is used in Hall C at Jefferson Lab to probe nucleon, baryon and nuclear structure. The experimental program in Hall C includes studies of semi-inclusive pion production, p, d(e, e'π±)X, where low energy factorization has been observed, suggesting that these reactions can be used to probe nucleon structure, including transverse momentum distributions of quarks, at energies available at JLab after the upcoming 12 GeV upgrade.
NASA Astrophysics Data System (ADS)
Kageya, Tsuneo
2014-01-01
Psuedo-scalar meson photo production measurements have been carried out with longitudinally-polarized neutrons using the circularly and linearly polarized photon beams and the CLAS at Thomas Jefferson National Accelerator Facility (Jlab). The experiment aims to obtain a complete set of spin observables on an efficient neutron target. Preliminary E asymmetries for the exclusive reaction, γ + n(p) → π- + p(p), selecting quasi free neutron kinematics are discussed.
g8b Experiment at JLab: Photoproduction of PHI meson
Salamanca, Julian; Cole, Philip
2009-01-01
The experiments using polarized photos, at threshold energies, have been taken as relevant experiments because the physics behind them is expected to explain a bunch of problems into the hadronic physics. The nature of parity exchange at threshold energies, strangeness content of proton, violation of Okubo-Zweig-Iizuka observation (OZI rule), are examples of them. Photoproduction of vector mesons by using polarized photons gives a very important way to study those issues. Our goal will be measure the $\\vec {\\gamma} p \\rightarrow \\phi p $ reaction, with $\\phi \\rightarrow K^{+}K^{-} $, in the photon energy range of 1.7GeV to 2.1 GeV by using a Coherent Linear Polarized Photon Beam in Hall-B at Thomas Jefferson Laboratory (Newport News, VA). The experiment where data were taken was called "g8b".
Studies of Nucleon Resonance Structure in Exclusive Meson Electroproduction
Aznauryan, Inna G.; Bashir, Adnan; Braun, Vladimir M.; Brodsky, Stanley J.; Burkert, Volker D.; Chang, L.; Chen, Ch.; El-Bennich, Bruno O.; Cloet, Ian C.; Cole, Philip L.; Edwards, Robert G.; Fedotov, Gleb V.; Giannini, Mauro M.; Gothe, Ralf W.; Lin, Huey-Wen; Kroll, Peter; Lee, T.-S. H.; Melnitchouk, Wally; Mokeev, Viktor I; Pena, Maria Teresa; Ramalho, Gilberto T.F.; Roberts, Craig D.; Santopinto, Elena; De Teramond, Guy F.; Tsushima, Kazuo; Wilson, David J.
2013-06-01
The studies of N* structure represent a key direction in the N* Program with CLAS detector. After 12 GeV Upgrade, the dedicated experiment on the studies of N* structure at largest photon virtualities ever achieved Q^2<12 GeV^2 is scheduled for the first year of running with the CLAS12 detector. The current status and plans for theory support of the N* structure studies in exclusive meson electroproduction are presented. They include the recent advances in the reaction theory for extraction of N* electrocouplings from the data and the approaches for high level theoretical interpretation of these fundamental quantities, allowing us to access dynamics of non-perturbative strong interaction which is responsible for the resonance formation and explore how it emerges from QCD.
Summary of the [eta]-meson sessions
Chrien, R.E.
1993-01-01
This summary describes the contents of the nineteen talks related to research on the [eta] meson and presented at the Workshop of Future Directions. The subjects of this area include threshold [eta] production, [eta]-nuclear spectroscopy, baryon spectroscopy, [eta] decays, facilities, and instrumentation.
Summary of the {eta}-meson sessions
Chrien, R.E.
1993-06-01
This summary describes the contents of the nineteen talks related to research on the {eta} meson and presented at the Workshop of Future Directions. The subjects of this area include threshold {eta} production, {eta}-nuclear spectroscopy, baryon spectroscopy, {eta} decays, facilities, and instrumentation.
Extracting excited mesons from the finite volume
Doring, Michael
2014-12-01
As quark masses come closer to their physical values in lattice simulations, finite volume effects dominate the level spectrum. Methods to extract excited mesons from the finite volume are discussed, like moving frames in the presence of coupled channels. Effective field theory can be used to stabilize the determination of the resonance spectrum.
Charmonium meson and hybrid radiative transitions
Guo, Peng; Yépez-Martínez, Tochtli; Szczepaniak, Adam P.
2014-06-01
We consider the non-relativistic limit of the QCD Hamiltonian in the Coulomb gauge, to describe radiative transitions between conventional charmonium states and from the lowest multiplet of cc¯ hybrids to charmonium mesons. The results are compared to potential quark models and lattices calculations.
QED effects in the pseudoscalar meson sector
NASA Astrophysics Data System (ADS)
Horsley, R.; Nakamura, Y.; Perlt, H.; Pleiter, D.; Rakow, P. E. L.; Schierholz, G.; Schiller, A.; Stokes, R.; Stüben, H.; Young, R. D.; Zanotti, J. M.
2016-04-01
In this paper we present results on the pseudoscalar meson masses from a fully dynamical simulation of QCD+QED, concentrating particularly on violations of isospin symmetry. We calculate the π +- π 0 splitting and also look at other isospin violating mass differences. We have presented results for these isospin splittings in [1]. In this paper we give more details of the techniques employed, discussing in particular the question of how much of the symmetry violation is due to QCD, arising from the different masses of the u and d quarks, and how much is due to QED, arising from the different charges of the quarks. This decomposition is not unique, it depends on the renormalisation scheme and scale. We suggest a renormalisation scheme in which Dashen's theorem for neutral mesons holds, so that the electromagnetic self-energies of the neutral mesons are zero, and discuss how the self-energies change when we transform to a scheme such as overline{M S} , in which Dashen's theorem for neutral mesons is violated.
[ital CPT], strings, and meson factories
Kostelecky, V.A. ); Potting, R. )
1995-04-01
Spontaneous breaking of [ital CPT] is possible in string theory. We show that it can arise at a level within reach of experiments at meson factories currently being built or designed. For [phi], [ital B], and [tau]-charm factories, we discuss the likely experimental string signatures and provide estimates of the bounds that might be attained in these machines.
CPT violation and B-meson oscillations
Kostelecky, V. Alan; Van Kooten, Richard J.
2010-11-15
Recent evidence for anomalous CP violation in B-meson oscillations can be interpreted as resulting from CPT violation. This yields the first sensitivity to CPT violation in the B{sub s}{sup 0} system, with the relevant coefficient for CPT violation constrained at the level of parts in 10{sup 12}.
Meson wave function from holographic models
Vega, Alfredo; Schmidt, Ivan; Branz, Tanja; Gutsche, Thomas; Lyubovitskij, Valery E.
2009-09-01
We consider the light-front wave function for the valence quark state of mesons using the AdS/CFT correspondence, as has been suggested by Brodsky and Teramond. Two kinds of wave functions, obtained in different holographic Soft-Wall models, are discussed.
Charming Mesons with Baryons and Nuclei
NASA Astrophysics Data System (ADS)
Tolos, Laura
2013-11-01
The properties of charmed mesons in nuclear matter and nuclei are reviewed. Different frameworks are discussed paying a special attention to unitarized coupled-channel approaches which incorporate heavy-quark spin symmetry. Several charmed baryon states with negative parity are generated dynamically by the s-wave interaction between pseudoscalar and vector meson multiplets with 1/2+ and 3/2+ baryons. These states are compared to experimental data. Moreover, the properties of open-charm mesons in matter are analyzed. The in-medium solution accounts for Pauli blocking effects, and for the meson self-energies in a self-consistent manner. The behavior in the nuclear medium of the rich spectrum of dynamically-generated baryon states is studied as well as their influence in the self-energy and, hence, the spectral function of open charm. The possible experimental signatures of the in-medium properties of open charm are finally addressed, such as the formation of charmed nuclei, in connection with the future FAIR facility.
Skyrmions and vector mesons: a symmetric approach
Caldi, D.G.
1984-01-01
We propose an extension of the effective, low-energy chiral Lagrangian known as the Skyrme model, to one formulated by a non-linear sigma model generalized to include vector mesons in a symmetric way. The model is based on chiral SU(6) x SU(6) symmetry spontaneously broken to static SU(6). The rho and other vector mesons are dormant Goldstone bosons since they are in the same SU(6) multiplet as the pion and other pseudoscalars. Hence the manifold of our generalized non-linear sigma model is the coset space (SU(6) x SU(6))/Su(6). Relativistic effects, via a spin-dependent mass term, break the static SU(6) and give the vectors a mass. The model can then be fully relativistic and covariant. The lowest-lying Skyrmion in this model is the whole baryonic 56-plet, which splits into the octet and decuplet in the presence of relativistic SU(6)-breaking. Due to the built-in SU(6) and the presence of vector mesons, the model is expected to have better phenomenological results, as well as providing a conceptually more unified picture of mesons and baryons. 29 references.
Meson Spectroscopy at JLab@12 GeV
Celentano, Andrea
2013-03-01
Meson, being the simplest hadronic bound system, is the ideal "laboratory" to study the interaction between quarks, to understand the role of the gluons inside hadrons and to investigate the origin of color confinement. To perform such studies it is important to measure the meson spectrum, with precise determination of resonance masses and properties, looking for rare qbar q states and for unconventional mesons with exotic quantum numbers (i.e. mesons with quantum numbers that are not compatible with a qbar q structure). With the imminent advent of the 12 GeV upgrade of Jefferson Lab a new generation of meson spectroscopy experiments will start: "Meson-Ex" in Hall B and "GLUEX" in Hall D. Both will use photo-production to explore the spectrum of mesons in the light-quark sector, in the energy range of few GeVs.
Spin O decay angular distribution for interfering mesons in electroproduction
Funsten, H.; Gilfoyle, G.
1994-04-01
Self analyzing meson electroproduction experiments are currently being planned for the CEBAF CLAS detector. These experiments deduce the spin polarization of outgoing unstable spin s (?)0 mesons from their decay angular distribution, W({theta},{psi}). The large angular acceptance of the CLAS detector permits kinematic tracking of a sufficient number of these events to accurately determine electroproduction amplitudes from the deduced polarization. Maximum polarization information is obtained from W({theta},{psi}) for decay into spin 0 daughters. The helicity of the decaying meson is transferred to the daughter`s relative orbital angular momentum m-projection; none is {open_quotes}absorbed{close_quotes} into daughter helicities. The decaying meson`s helicity maximally appears in W({theta},{psi}). W({theta},{psi}) for spin 0 daughters has been derived for (1) vector meson electroproduction and (2) general interfering mesons produced by incident pions. This paper derives W({theta},{psi}) for electroproduction of two interfering mesons that decay into spin 0 daughters. An application is made to the case of interfering scalar and vector mesons. The derivation is an extension of work by Schil using the general decay formalism of Martin. The expressions can be easily extended to the case of N interfering mesons since interference occurs pairwise in the observable W ({theta},{psi}), a quadratic function of the meson amplitudes. The derivation uses the virtual photon density matrix of Schil which is transformed by a meson electroproduction transition operator, T. The resulting density matrix for the interfering mesons is then converted into a corresponding statistical tensor and contracted into the efficiency tensor for spin 0 daughters.
η meson production in nucleus and observation of in-medium behavior of N^*(1535)
NASA Astrophysics Data System (ADS)
Nagahiro, Hideko; Jido, Daisuke; Hirenzaki, Satoru
2009-10-01
The study of the in-medium hadron properties is one of the important subjects in nuclear physics. It would provide us useful information on chiral symmetry in finite density. In this contribution, we investigate the properties of the η-nucleus interaction in chiral models and discuss the possible observation of the in-medium behavior of the N^*(1535) resonance in experiments. The strong coupling of the ηN system to N^* enables us to investigate the in-medium properties of N^* through the η meson production in nuclei. For in-medium properties of N^*, there are some theoretical models paying respects to chiral symmetry. In the chiral doublet model, in which N^* is regarded as a chiral partner of nucleon, the effect of the partial restoration of chiral symmetry reduces the mass difference of N and N^* in the nuclear medium. On the other hand, the chiral unitary model, in which N^* is introduced as a resonance dynamically generated by meson- baryon scattering, predicts almost no mass shift of N^* in nuclear matter. To investigate the in-medium properties of N^*, we would like to discuss the formation probability of the η mesic nuclei by using the missing mass spectroscopy and also investigate the production reaction of the η meson off nuclei that has a different kinematics from the former reaction.
Decays of doubly charmed meson molecules
NASA Astrophysics Data System (ADS)
Molina, R.; Nagahiro, H.; Hosaka, A.
2016-01-01
If the X(3872), Y(3940) and X(4160) are D*D ¯+c .c ., D*D ¯* and DS*D¯S* molecules, respectively, there should be doubly charmed mesons (D(*)D(*)). In this talk we predict two states with JP = 1+ in the charm = 2 sector, one DD* state around 3850 MeV, other D*D* state with mass around 3970 MeV, and other two similar states in the (charm = 2; strangeness = sector. Besides that, we evaluate the decay widths of doubly charm mesons D*D*(1+), into DDπ and DDγ. These decays are mediated by anomalous couplings D*D* - DD*, with the subsequent decay of D* into Dπ or Dγ.
Time reversal violation for entangled neutral mesons
NASA Astrophysics Data System (ADS)
Bernabéu, J.
2013-07-01
A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique opportunity for a search of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and PHI, Factories. The two quantum effects of the first decay as a filtering measurement and the transfer of information to the still living partner allow performing a genuine TRV asymmetry with the exchange of "in" and "out" states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system.
Semileptonic B-Meson Decays at Babar
NASA Astrophysics Data System (ADS)
Sigamani, Michael
2011-10-01
Presented are selected results from semileptonic B-meson decays at BABAR. Two measurements of the Cabibbo-Kobayashi-Maskawa matrix element |Vcb| are reported, using moments of the hadronic-mass spectrum in inclusive bar B -> Xc l ^ - bar v decays, and also exclusive bar B -> Dl ^ - bar vl decays. These results are based on data samples of 232 (inclusive bar B -> Xc l ^ - bar v) and 460 (exclusive bar B -> Dl ^ - bar vl ) million Υ (4S) -> Bbar B decays recorded by the BABAR detector at the PEP-II e+e-storage rings. Semileptonic events are identified by requiring a lepton (e or μ) in events tagged by a full reconstruction of one of the B mesons in the Bbar B pair.
Meson exchange and neutral weak currents
Beck, D.H.
1994-04-01
Measurements of parity-violating electron scattering asymmetries to determine weak neutral currents in nuclei will be effected by the presence of meson exchange currents. Present low momentum transfer calculations, based on a flavor independent framework, show these effects to be small. In general, however, as the momentum transfer increases to values typical of deep-inelastic scattering, fragmentation functions show a clear flavor dependence. It is suggested that a good experimental starting point for understanding the flavor dependence of meson production and exchange currents is the Q{sup 2} dependence of parity-violating asymmetry in inclusive single pion electroproduction. A CEBAF facility with doubled energy is necessary to approach momentum transfers where this process begins to scale.
Weak Decays of Excited B Mesons
NASA Astrophysics Data System (ADS)
Grinstein, B.; Martin Camalich, J.
2016-04-01
We investigate the decays of the excited (b q ¯) mesons as probes of the short-distance structure of the weak Δ B =1 transitions. These states are unstable under the electromagnetic or strong interactions, although their widths are typically suppressed by phase space. Compared to the pseudoscalar B meson, the purely leptonic decays of the vector B* are not chirally suppressed and are sensitive to different combinations of the underlying weak effective operators. An interesting example is Bs*→ℓ+ℓ-, which has a rate that can be accurately predicted in the standard model. The branching fraction is B ˜10-11, irrespective of the lepton flavor and where the main uncertainty stems from the unmeasured and theoretically not well known Bs* width. We discuss the prospects for producing this decay mode at the LHC and explore the possibility of measuring the Bs*→ℓℓ amplitude, instead, through scattering experiments at the Bs* resonance peak.
The lightest hybrid meson supermultiplet in QCD
Dudek, Jozef J
2011-10-01
We interpret the spectrum of meson states recently obtained in non-perturbative lattice QCD calculations in terms of constituent quark-antiquark bound states and states, called 'hybrids', in which the q{bar q} pair is supplemented by an excitation of the gluonic field. We identify a lightest supermultiplet of hybrid mesons with J{sup PC} = (0,1,2){sup {-+}}, 1{sup -} built from a gluonic excitation of chromomagnetic character coupled to q{bar q} in an S-wave. The next lightest hybrids are suggested to be quark orbital excitations with the same gluonic excitation, while the next distinct gluonic excitation is significantly heavier. Existing models of gluonic excitations are compared to these findings and possible phenomenological consequences explored.
Non-conventional mesons at PANDA
NASA Astrophysics Data System (ADS)
Giacosa, Francesco
2015-04-01
Non-conventional mesons, such as glueballs and tetraquarks, will be in the focus of the PANDA experiment at the FAIR facility. In this lecture we recall the basic properties of QCD and describe some features of unconventional states. We focus on the search of the not-yet discovered glueballs and the use of the extended Linear Sigma Model for this purpose, and on the already discovered but not-yet understood X, Y, Z states.
Electromagnetic charge radii of pseudoscalar mesons
Bagchi, B.; Lahiri, A.; Niyogi, S.
1989-06-01
The charge radii of the pseudoscalar mesons ..pi../sup +/, /ital K//sup +/, and /ital K//sup 0/ are analyzed in an extended vector-dominance framework and the results are compared with those which follow the nonrelativistic quark model and constituent-quark triangle loop approach. Further, estimates of the root-mean-square relative coordinate parameter are obtained which are in conformity with normal theoretical expectations.
Understanding the baryon and meson spectra
Pennington, Michael R.
2013-10-01
A brief overview is given of what we know of the baryon and meson spectra, with a focus on what are the key internal degrees of freedom and how these relate to strong coupling QCD. The challenges, experimental, theoretical and phenomenological, for the future are outlined, with particular reference to a program at Jefferson Lab to extract hadronic states in which glue unambiguously contributes to their quantum numbers.
Strangeness and meson-nucleon sigma terms
Dahiya, Harleen; Sharma, Neetika
2011-10-21
The chiral constituent quark model ({chi}CQM) has been extended to calculate the flavor structure of the nucleon through the meson-nucleon sigma terms which have large contributions from the quark sea and are greatly affected by chiral symmetry breaking and SU(3) symmetry breaking. The hidden strangeness component in the nucleon has also been investigated and its significant contribution is found to be consistent with the recent available experimental observations.
Rare B Meson Decays at the Tevatron
Hopkins, Walter
2012-01-01
Rare B meson decays are an excellent probe for beyond the Standard Model physics. Two very sensitive processes are the b {yields} s{mu}{sup +}{mu}{sup -} and B{sub s,d}{sup 0} {yields} {mu}{sup +}{mu}{sup -} decays. We report recent results at a center of mass energy of {radical}s = 1.96 TeV from CDF II using 7 fb{sup -1} at the Fermilab Tevatron Collider.
Mesonic spectroscopy of minimal walking technicolor
Del Debbio, Luigi; Lucini, Biagio; Patella, Agostino; Pica, Claudio; Rago, Antonio
2010-07-01
We investigate the structure and the novel emerging features of the mesonic nonsinglet spectrum of the minimal walking technicolor theory. Precision measurements in the nonsinglet pseudoscalar and vector channels are compared to the expectations for an IR-conformal field theory and a QCD-like theory. Our results favor a scenario in which minimal walking technicolor is (almost) conformal in the infrared, while spontaneous chiral symmetry breaking seems less plausible.
Helicity operators for mesons in flight on the lattice
Christopher E. Thomas; Edwards, Robert G.; Dudek, Jozef J.
2012-01-20
Motivated by the desire to construct meson-meson operators of definite relative momentum in order to study resonances in lattice QCD, we present a set of single-meson interpolating fields at non-zero momentum that respect the reduced symmetry of a cubic lattice in a finite cubic volume. These operators follow from the subduction of operators of definite helicity into irreducible representations of the appropriate little groups. We show their effectiveness in explicit computations where we find that the spectrum of states interpolated by these operators is close to diagonal in helicity, admitting a description in terms of single-meson states of identified J^{PC}. Lastly, the variationally determined optimal superpositions of the operators for each state give rapid relaxation in Euclidean time to that state, ideal for the construction of meson-meson operators and for the evaluation of matrix elements at finite momentum.
Towards a Theoretical Understanding of the XYZ Mesons from QCD
NASA Astrophysics Data System (ADS)
Braaten, Eric
2016-03-01
The XYZ mesons are mesons that contain a heavy quark and antiquark but have properties that seem to require additional constituents. Some of them are electrically charged, so they must be tetraquark mesons whose additional constituents are a light quark and antiquark. The list of XYZ mesons has grown to about two dozen over the last decade. A promising approach to understanding these mesons within QCD is the Born-Oppenheimer approximation, which reduces the problem to the solution of the Schrödinger equation in potentials that can be calculated using lattice QCD. The Born-Oppenheimer approximation has not yet revealed the pattern of the XYZ mesons, but it provides a compelling framework for understanding them from the fundamental theory.
Radius of the ρ meson determined from its decay constant
NASA Astrophysics Data System (ADS)
Krutov, A. F.; Polezhaev, R. G.; Troitsky, V. E.
2016-02-01
We present a unified model describing electroweak properties of the π and ρ mesons. Using a general method of the relativistic parametrization of matrix elements of local operators, adjusted for the nondiagonal in the total angular momentum case, we calculate the ρ -meson lepton-decay constant fρ using the same parameters of free constituent quarks that have ensured exclusively good results for the π meson previously. The only free parameter, characterizing quark interactions, which include an additional spin-spin contribution and hence differ from the π -meson case, is fixed by matching the decay constant to its experimental value. The mean square charge radius is calculated, ⟨rρ2⟩=(0.56 ±0.04 ) fm2 . This result confirms, for the ρ -meson case, the conjecture of equality between electromagnetic and strong radii of hadrons. This conjecture was tested previously for proton, π and K mesons.
Helicity operators for mesons in flight on the lattice
Christopher E. Thomas; Edwards, Robert G.; Dudek, Jozef J.
2012-01-20
Motivated by the desire to construct meson-meson operators of definite relative momentum in order to study resonances in lattice QCD, we present a set of single-meson interpolating fields at non-zero momentum that respect the reduced symmetry of a cubic lattice in a finite cubic volume. These operators follow from the subduction of operators of definite helicity into irreducible representations of the appropriate little groups. We show their effectiveness in explicit computations where we find that the spectrum of states interpolated by these operators is close to diagonal in helicity, admitting a description in terms of single-meson states of identified JPC.more » Lastly, the variationally determined optimal superpositions of the operators for each state give rapid relaxation in Euclidean time to that state, ideal for the construction of meson-meson operators and for the evaluation of matrix elements at finite momentum.« less
Φ-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies
Salamanca, Julian; Cole, Philip L
2007-10-01
The observables provided by linearly-polarized photons are of interest in delineating the contributions of the various hadronic processes giving rise to vector meson photoproduction. In particular, we describe how Φ-meson production affords an incisive tool for exploring the nature of the parity exchange at threshold energies, the strangeness content of proton, as well as extracting signatures for the violation of Okubo-Zweig-Iizuka observation (OZI rule). Our goal is to study the γp → Φp reaction, with Φ → K^{+}K^{-}, in the photon energy range of 1.7 to 2.1 GeV by using the Coherent Linear Bremsstrahlung Facility in Hall B of Jefferson Laboratory, Newport News, VA. The data were collected during the g8b run in the summer of 2005.
Study of ω-meson production in pp collisions at ANKE
NASA Astrophysics Data System (ADS)
Barsov, S.; Büscher, M.; Hartmann, M.; Hejny, V.; Kacharava, A.; Keshelashvili, I.; Khoukaz, A.; Koptev, V.; Kulessa, P.; Kulikov, A.; Lehmann, I.; Leontyev, V.; Macharashvili, G.; Maeda, Y.; Mersmann, T.; Merzliakov, S.; Mikirtytchyants, S.; Mussgiller, A.; Oellers, D.; Ohm, H.; Rathmann, F.; Schleichert, R.; Seyfarth, H.; Ströher, H.; Trusov, S.; Valdau, Yu.; Wüstner, P.; Yaschenko, S.; Wilkin, C.
2007-01-01
The production of ω-mesons in the pp → ppω reaction has been investigated with the COSY-ANKE spectrometer for excess energies of 60 and 92MeV by detecting the two final protons and reconstructing their missing mass. The large physical background was subtracted using an event-by-event transformation of the proton momenta between the two energies. Differential distributions and total cross-sections were obtained after careful studies of possible systematic uncertainties in the overall ANKE acceptance. The results are compared with the predictions of theoretical models. Combined with data on the φ-meson, a more refined estimate is made of the Okubo-Zweig-Iizuka rule violation in the φ/ω production ratio.
Exclusive electroproduction of strange mesons with JLab 12 GeV
Strikman, Mark; Weiss, Christian
2009-01-01
We summarize the physics topics which can be addressed by measurements of high-Q^2 exclusive electroproduction of strange mesons, gamma* N -> phi N, K* Lambda, K Lambda, K Sigma, at Jefferson Lab with 11 GeV beam energy. The proposed investigations are aimed both at exploring the reaction mechanism (dominance of point-like configurations) and extracting information about baryon structure from the data (generalized parton distributions, or GPDs). They include (a) probing the t-dependence of the nucleon's gluon GPD (transverse spatial distribution of gluons) in phi meson production; (b) separating the nucleon helicity-flip and nonflip quark GPDs in K* Lambda production with measurement of the Lambda recoil polarization; (c) probing strangeness polarization in the nucleon in K Lambda and K Sigma production. These studies rely only on the analysis of cross section ratios, which are less affected by the theoretical uncertainties of present GPD-based calculations than absolute cross sect
Aihara, H.; Alston-Garnjost, M.; Avery, R.E.; Barbaro-Galtieri, A.; Barker, A.R.; Barnett, B.A.; Bauer, D.A.; Bay, A.; Bobbink, G.J.; Buchanan, C.D.; Buijs, A.; Caldwell, D.O.; Chao, H.; Chun, S.; Clark, A.R.; Cowan, G.D.; Crane, D.A.; Dahl, O.I.; Daoudi, M.; Derby, K.A.; Eastman, J.J.; Eberhard, P.H.; Edberg, T.K.; Eisner, A.M.; Erne, F.C.; Fairfield, K.H.; Hauptman, J.M.; Hofmann, W.; Hylen, J.; Kamae, T.; Kaye, H.S.; Kenney, R.W.; Khacheryan, S.; Kofler, R.R.; Langeveld, W.G.J.; Layter, J.G.; Lin, W.T.; Linde, F.L.; Loken, S.C.; Lu, A.; Lynch, G.R.; Madaras, R.J.; Magnuson, B.D.; Masek, G.E.; Mathis, L.G.; Matthews, J.A.J.; Maxfield, S.J.; Miller, E.S.; Moses, W.; Nygren, D.R.; Oddone, P.J.; Paar, H.P.; Park, S.K.; Pellett, D.E.; Pripstein, M.; Ronan, M.T.; Ross, R.R.; Rouse, F.R.; Schwitkis, K.A.; Sens, J.C.; Shapiro, G.; Shen, B.C.; Smith, J.R.; Steinman, J.S.; Stephens, R.W.; Stevenson, M.L.; Stork, D.H.; Strauss, M.G.; Sullivan, M.K.; Takahashi, T.; Toutounchi, S.; van Tyen, R.; TPC /Two-Gamma Collaboration
1990-01-08
The TPC/Two-Gamma facility at the SLAC {ital e}{sup +}{ital e}{sup {minus}} storage ring PEP was used to study the reactions {gamma}{gamma}{sup *}{r arrow}{eta} and {gamma}{gamma}{sup *}{r arrow}{eta}{prime}. The {eta}{gamma}{sup *}{gamma} and {eta}{prime}{gamma}{sup *}{gamma} transition form factors were measured as functions of {ital Q}{sup 2}, the negative of the invariant mass squared of the tagged photon, in the range 0.1{lt}{ital Q}{sup 2}{lt}7 GeV{sup 2}. These determinations of the electromagnetic structure of the {eta} and {eta}{prime} mesons are consistent with both vector-meson dominance and QCD. They also provide new measurements of the pseudoscalar mixing angle and decay constants.
{phi}-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies
Salamanca, Julian; Cole, Philip L.
2007-10-26
The observables provided by linearly-polarized photons are of interest in delineating the contributions of the various hadronic processes giving rise to vector meson photoproduction. In particular, we describe how {phi}-meson production affords an incisive tool for exploring the nature of the parity exchange at threshold energies, the strangeness content of proton, as well as extracting signatures for the violation of Okubo-Zweig-Iizuka observation (OZI rule). Our goal is to study the {gamma}-vectorp{yields}{phi}p reaction, with {phi}{yields}K{sup +}K{sup -}, in the photon energy range of 1.7 to 2.1 GeV by using the Coherent Linear Bremsstrahlung Facility in Hall B of Jefferson Laboratory, Newport News, VA. The data were collected during the g8b run in the summer of 2005.
Time reversal violation for entangled neutral mesons
Bernabeu, J.
2014-07-23
A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique solution for the test of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and φ, Factories. The two quantum effects of the decays as filtering measurements of the meson states and the transfer of information of the first decay to the still living partner allow performing a genuine TRV asymmetry with the exchange of “in” and “out” states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system. The perspectives for future additional studies of TRV are discussed.
Time reversal violation for entangled neutral mesons
NASA Astrophysics Data System (ADS)
Bernabeu, J.
2014-07-01
A direct evidence for Time Reversal Violation (TRV) means an experiment that, considered by itself, clearly shows TRV independent of, and unconnected to, the results for CP Violation. No existing result before the recent BABAR experiment with entangled neutral B mesons had demonstrated TRV in this sense. There is a unique solution for the test of TRV with unstable particles thanks to the Einstein-Podolsky-Rosen (EPR) Entanglement between the two neutral mesons in B, and φ, Factories. The two quantum effects of the decays as filtering measurements of the meson states and the transfer of information of the first decay to the still living partner allow performing a genuine TRV asymmetry with the exchange of "in" and "out" states. With four independent TRV asymmetries, BABAR observes a large deviation of T-invariance with a statistical significance of 14 standard deviations, far more than needed to declare the result as a discovery. This is the first direct observation of TRV in the time evolution of any system. The perspectives for future additional studies of TRV are discussed.
Hard Exclusive Meson Production at COMPASS
NASA Astrophysics Data System (ADS)
Ter Wolbeek, Johannes
2016-02-01
The concept of Generalized Parton Distributions (GPDs) combines two-dimensional spatial information given by form factors, with longitudinal momentum information from Parton Distribution Functions. GPDs provide comprehensive description of the nucleon structure involving a wealth of new information. For instance, according to Ji’s sum rule, the GPDs H and E enable access to the total angular momenta of quarks, antiquarks and gluons. While H can be approached using measurements of electroproduction cross sections, asymmetry measurements in hard exclusive meson production off transversely polarized targets can help to constrain the GPD E and chiral-odd GPDs. In 2007 and 2010 the COMPASS experiment at CERN collected data by scattering a 160GeV/c muon beam off a transversely polarized NH3 target. Exclusive vector-meson production μ + p → μ‧ + p + V with a ρ0 or ω meson in the final state is studied and five single-spin and three double-spin azimuthal asymmetries are measured.
Vector Meson Form Factors and Wave Functions from Holographic QCD
Hovhannes Grigoryan; Anatoly Radyushkin
2007-10-10
Based on the holographic dual model of QCD, we study 2- and 3-point functions of vector currents and derive form factors as well as wave functions for the vector mesons. As a result, generalized vector-meson dominance representation for form factors is obtained with a very specific VMD pattern. The calculated electric radius of the rho-meson is shown to be in a good agreement with predictions from lattice QCD.
Search for medium effects on light vector mesons
Djalali, C; Nasseripour, R; Weygand, D P; Wood, M H
2007-02-01
The photoproduction of vector mesons on various nuclei has been studied using the Cebaf Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory. The rho, omega, and phi mesons are observed via their decay to e^{+}e^{₋}. The rho spectral function is extracted from the data on carbon, iron, and titanium. We observe no effects on the mass of the rho meson, some widening in titanium and iron is observed consistent with standard collisional broadening.
Phi meson propagation in a hot hadronic gas
Alvarez-Ruso, Luis; Koch, Volker
2002-02-20
The Hidden Local Symmetry Lagrangian is used to study the interactions of phi mesons with other pseudoscalar and vector mesons in a hadronic gas at finite temperature. We have found a significantly small phi mean free path (less than 2.4 fm at T > 170 MeV) due to large collision rates with rho mesons, kaons and predominantly K* in spite of their heavy mass. This implies that phi mesons produced after hadronization in relativistic heavy ion collisions will not leave the hadronic system without scattering. The effect of these interactions on the time evolution of the phi density in the expanding hadronic fireball is investigated.
Search for gluonic excitations in light unconventional mesons
Paul Eugenio
2007-07-01
Studies of meson spectra via strong decays provide insight regarding QCD at the confinement scale. These studies have led to phenomenologicalmodels for QCD such as the constituent quark model. However, QCD allows for a much richer spectrum of meson states which include extra states such as exotics, hybrids, multi-quarks, and glueballs. First discussion of the status of exotic meson searches is given followed by a discussion of plans at Jefferson Lab to double the energy of the machine to 12 GeV, which will allow us to access photoproduction of mesons in search for gluonic excited states.
Scattering amplitudes to all orders in meson exchange
Silbar, R.R.; Mattis, M.P.
1990-01-01
As the number of colors in QCD, N{sub C}, becomes large, it is possible to sum up all meson-exchange contributions, however arbitrarily complicated, to meson-baryon and baryon-baryon scattering. A semi-classical structure for the two-flavor theory emerges, in close correspondence to vector-meson-augmented Skyrme models. In this limit, baryons act as extended static sources for the classical meson fields. This leads to non-linear differential equations for the classical meson fields which can be solved numerically for static radial (hedgehog-like) solutions. The non-linear terms in the equations of motion for the quantized meson fields can then be simplified, to leading order in 1/N{sub C}, by replacing all factors of the meson field but one by the previously-found classical field. This results in linear, Schroedinger-like equations, which are easily solved. For the meson-baryon case the solution can be subsequently analyzed to obtain the phase shifts for the scattering and, from these, the baryon resonance spectrum of the model. As the warm-up, we have carried out this calculation for the simple case of {sigma} mesons only, finding sensible results. 8 refs., 3 figs.
In-medium properties of light vector mesons
C. Djalali; R. Nasseripour; D. P. Weygand; M. H. Wood
2007-08-01
The photoproduction of vector mesons on various nuclei has been studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Laboratory. All three vector mesons ρ, ω and phi are observed via their decay to e+e-. The possible in-medium effects on the properties of the ρ meson are of particular interest. The ρ spectral function is extracted from the data on carbon, iron and titanium, and compared to the spectrum from liquid deuterium, which is relatively free of nuclear effects. We observe no effects on the mass of the ρ meson, some widening in titanium and iron is observed consistent with the collisional broadening.
Search for medium modifications of the rho meson.
Nasseripour, R; Wood, M H; Djalali, C; Weygand, D P; Tur, C; Mosel, U; Muehlich, P; Adams, G; Amaryan, M J; Ambrozewicz, P; Anghinolfi, M; Asryan, G; Avakian, H; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Battaglieri, M; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Blaszczyk, L; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Burkert, V D; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Casey, L; Chen, S; Cole, P L; Collins, P; Coltharp, P; Crabb, D; Crannell, H; Crede, V; Cummings, J P; Dashyan, N; De Masi, R; De Vita, R; De Sanctis, E; Degtyarenko, P V; Denizli, H; Dennis, L; Deur, A; Dharmawardane, K V; Dickson, R; Dodge, G E; Doughty, D; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Feldman, G; Feuerbach, R J; Funsten, H; Garçon, M; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Gordon, C I O; Gothe, R W; Griffioen, K A; Guidal, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hafidi, K; Hakobyan, H; Hakobyan, R S; Hanretty, C; Hardie, J; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Jo, H S; Johnstone, J R; Joo, K; Juengst, H G; Kalantarians, N; Kellie, J D; Khandaker, M; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Kossov, M; Krahn, Z; Kramer, L H; Kubarovsky, V; Kuhn, J; Kuhn, S E; Kuleshov, S V; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Li, Ji; Livingston, K; Lu, H Y; Maccormick, M; Markov, N; Mattione, P; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mehrabyan, S; Melone, J J; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Moriya, K; Morrow, S A; Moteabbed, M; Mueller, J; Munevar, E; Mutchler, G S; Nadel-Turonski, P; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Niyazov, R A; Nozar, M; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Anefalos Pereira, S; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Sabatié, F; Salamanca, J; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabian, Y G; Sharov, D; Shvedunov, N V; Smith, E S; Smith, L C; Sober, D I; Sokhan, D; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Taiuti, M; Tedeschi, D J; Tkabladze, A; Tkachenko, S; Todor, L; Ungaro, M; Vineyard, M F; Vlassov, A V; Watts, D P; Weinstein, L B; Williams, M; Wolin, E; Yegneswaran, A; Zana, L; Zhang, B; Zhang, J; Zhao, B; Zhao, Z W
2007-12-31
The photoproduction of vector mesons on various nuclei has been studied using the CLAS detector at Jefferson Laboratory. The vector mesons, rho, omega, and varphi, are observed via their decay to e;{+}e;{-}, in order to reduce the effects of final-state interactions in the nucleus. Of particular interest are possible in-medium effects on the properties of the rho meson. The rho mass spectrum is extracted from the data on various nuclei, 2H, C, Fe, and Ti. We observe no significant mass shift and some broadening consistent with expected collisional broadening for the rho meson. PMID:18233570
Barnes, T. |
1992-12-31
In this talk I summarize recent calculations of meson-meson scattering amplitudes in the nonrelativistic quark potential model, which assume that the scattering mechanism is one-gluon-exchange followed by constituent exchange (OGE+CEX). We refer to the scattering diagrams as ``quark Born diagrams``. For the cases chosen to isolate this mechanism, I=2 {pi}{pi} and I=3/2 K{pi}, the theoretical results are in remarkably good agreement with experimental S- and P-wave phase shifts and PCAC scattering lengths, given standard potential-model parameters.
Barnes, T. Tennessee Univ., Knoxville, TN . Dept. of Physics)
1992-01-01
In this talk I summarize recent calculations of meson-meson scattering amplitudes in the nonrelativistic quark potential model, which assume that the scattering mechanism is one-gluon-exchange followed by constituent exchange (OGE+CEX). We refer to the scattering diagrams as quark Born diagrams''. For the cases chosen to isolate this mechanism, I=2 [pi][pi] and I=3/2 K[pi], the theoretical results are in remarkably good agreement with experimental S- and P-wave phase shifts and PCAC scattering lengths, given standard potential-model parameters.
The hybrid mesons quest: the MesonEx experiment at Jefferson Laboratory
NASA Astrophysics Data System (ADS)
Rizzo, A.; CLAS Collaboration
2016-02-01
The meson spectroscopy plays nowadays a central role in the investigation of hadron structure thanks to the possible existence of exotic hybrid mesons, quark-antiquark-gluon bound states. Their explicit gluonic degrees of freedom which should clearly emerge from a Partial Wave Analysis (PWA) of the corresponding Dalitz plot of the exotic particle decay, may result in final JPC configurations not allowed in the constituent quark model. Besides this clear signature, hybrid mesons are also expected to have a large particle multiplicity decays, requiring for their search an experimental apparatus with high performances in terms of rate capability, resolution and almost a full acceptance to apply PWA methods. New-generation experiments are planned at Thomas Jefferson National Laboratory (VA, USA) for which an unprecedented statistics of large multiplicity decay events with fully reconstructed kinematics will be available. In particular for the MesonEx (CLAS12) experiment in Hall B, a wide scientific program that will start in 2016 has been deployed to study the meson spectrum at energies up to 11 GeV. A key role in such program is played by the Forward Tagger apparatus of the experiment, which will allow to extend the study of meson electro-production to very low Q2 values, in a quasi-real photo production kinematical region, where the production of hybrid mesons is expected to be favorite. Currently a new analysis framework for the search of the hybrid mesons is being set up by the HASPECT network, an international structure which gather people involved into theoretical and experimental hadronic physics all over the world. The goals of the network is to develop new analysis models and statistical techniques to unfold the signal and background distributions in high-statistics datasets. In this work are briefly presented the first preliminary results from the application of a statistical technique, namely the sPlot, to the data already acquired by the CLAS experiment for
Electroproduction of pseudoscalar mesons above the resonance region
Niczyporuk, B.B.
1994-04-01
In this paper, the author has revisited twenty year old data considering the progress achieved in related fields. To make further progress in our understanding of strong interactions, one needs much better quality of exclusive electroproduction data. A measurement of the differential cross section {sigma}(t, W, Q{sup 2}) for the reactions e{sup {minus}} + p {r_arrow} e{sup {minus}} + {pi}{sup +}(K{sup +}) + n({Lambda}{degrees}) at a beam energy of {ge} 4 GeV is proposed. Data will be collected simultaneously for both reactions using the CLAS detector at CEBAF in the following kinematical region: Q{sup 2} > 1 GeV{sup 2} and W > 2 GeV. One of the most interesting aspects of electroproduction is that it can be used to measure photoproduction amplitudes as functions of the photon mass squared Q{sup 2} and momentum transfer t. Emphasis is given to measuring the differential cross sections for t {approximately} m{sup 2}{sub {pi},{kappa}}. Above the resonance region (W > 2 GeV), the cross section is dominated by the amplitudes for scalar photons. Measured angular distributions of produced mesons will be used to estimate the contribution of various amplitudes to the cross sections. High statistics and good quality data collected simultaneously using a large acceptance detector will improve our understanding of nucleon structure as well as the hadronic properties of the photon.
Decay constants of p and d wave heavy light mesons
Veseli, Sinisa; Dunietz, Isard
1996-07-01
We investigate decay constants of P- and D-wave heavy-light mesons within the mock-meson approach. Numerical estimates are obtained using the relativistic quark model. We also comment on recent calculations of heavy-light pseudo-scalar and vector decay constants.
First measurement of the B S meson mass
NASA Astrophysics Data System (ADS)
Buskulic, D.; De Bonis, I.; Decamp, D.; Ghez, P.; Goy, C.; Lees, J.-P.; Minard, M.-N.; Pietrzyk, B.; Ariztizabal, F.; Comas, P.; Crespo, J. M.; Delfino, M.; Efthymiopoulos, I.; Fernandez, E.; Fernandez-Bosman, M.; Gaitan, V.; Garrido, Ll.; Mattison, T.; Pacheco, A.; Padilla, C.; Pascual, A.; Creanza, D.; de Palma, M.; Farilla, A.; Iaselli, G.; Maggi, G.; Natali, S.; Nuzzo, S.; Quattromini, M.; Ranieri, A.; Raso, G.; Romano, F.; Ruggieri, F.; Selvaggi, G.; Silvestris, L.; Tempesta, P.; Zito, G.; Chai, Y.; Hu, H.; Huang, D.; Huang, X.; Lin, J.; Wang, T.; Xie, Y.; Xu, D.; Xu, R.; Zhang, J.; Zhang, L.; Zhao, W.; Blucher, E.; Bonvicini, G.; Boudreau, J.; Casper, D.; Drevermann, H.; Forty, R. W.; Ganis, G.; Gay, C.; Hagelberg, R.; Harvey, J.; Haywood, S.; Hilgart, J.; Jacobsen, R.; Jost, B.; Knobloch, J.; Lehraus, I.; Lohse, T.; Maggi, M.; Markou, C.; Martinez, M.; Mato, P.; Meinhard, H.; Minten, A.; Miotto, A.; Miquel, R.; Moser, H.-G.; Palazzi, P.; Pater, J. R.; Perlas, J. A.; Pusztaszeri, J.-F.; Ranjard, F.; Redlinger, G.; Rolandi, L.; Rothberg, J.; Ruan, T.; Saich, M.; Schlatter, D.; Schmelling, M.; Sefkow, F.; Tejessy, W.; Veenhof, R.; Wachsmuth, H.; Wiedenmann, W.; Wildish, T.; Witzeling, W.; Wotschack, J.; Ajaltouni, Z.; Badaud, F.; Bardadin-Otwinowska, M.; El Fellous, R.; Falvard, A.; Gay, P.; Guicheney, C.; Henrard, P.; Jousset, J.; Michel, B.; Montret, J.-C.; Pallin, D.; Perret, P.; Podlyski, F.; Proriol, J.; Prulhière, F.; Saadi, F.; Fearnley, T.; Hansen, J. D.; Hansen, J. R.; Hansen, P. H.; Møllerud, R.; Nilsson, B. S.; Kyriakis, A.; Simopoulou, E.; Vayaki, A.; Zachariadou, K.; Badier, J.; Blondel, A.; Bonneaud, G.; Brient, J. C.; Fouque, G.; Orteu, S.; Rougé, A.; Rumpf, M.; Tanaka, R.; Verderi, M.; Videau, H.; Candlin, D. J.; Parsons, M. I.; Veitch, E.; Focardi, E.; Moneta, L.; Parrini, G.; Corden, M.; Georgiopoulos, C.; Ikeda, M.; Lannutti, J.; Levinthal, D.; Sawyer, L.; Wasserbaech, S.; Antonelli, A.; Baldini, R.; Bencivenni, G.; Bologna, G.; Bossi, F.; Campana, P.; Capon, G.; Cerutti, F.; Chiarella, V.; D'Ettorre-Piazzoli, B.; Felici, G.; Laurelli, P.; Mannocchi, G.; Murtas, F.; Murtas, G. P.; Passalacqua, L.; Pepe-Altarelli, M.; Picchi, P.; Colrain, P.; ten Have, I.; Lynch, J. G.; Maitland, W.; Morton, W. T.; Raine, C.; Reeves, P.; Scarr, J. M.; Smith, K.; Smith, M. G.; Thompson, A. S.; Turnbull, R. M.; Brandl, B.; Braun, O.; Geweniger, C.; Hanke, P.; Hepp, V.; Kluge, E. E.; Maumary, Y.; Putzer, A.; Rensch, B.; Stahl, A.; Tittel, K.; Wunsch, M.; Beuselinck, R.; Binnie, D. M.; Cameron, W.; Cattaneo, M.; Colling, D. J.; Dornan, P. J.; Greene, A. M.; Hassard, J. F.; Lieske, N. M.; Moutoussi, A.; Nash, J.; Patton, S.; Payne, D. G.; Phillips, M. J.; San Martin, G.; Sedgbeer, J. K.; Tomalin, I. R.; Wright, A. G.; Girtler, P.; Kneringer, E.; Kuhn, D.; Rudolph, G.; Bowdery, C. K.; Brodbeck, T. J.; Finch, A. J.; Foster, F.; Hughes, G.; Jackson, D.; Keemer, N. R.; Nuttall, M.; Patel, A.; Sloan, T.; Snow, S. W.; Whelan, E. P.; Kleinknecht, K.; Raab, J.; Renk, B.; Sander, H.-G.; Schmidt, H.; Steeg, F.; Walther, S. M.; Wanke, R.; Wolf, B.; Bencheikh, A. M.; Benchouk, C.; Bonissent, A.; Carr, J.; Coyle, P.; Drinkard, J.; Etienne, F.; Nicod, D.; Papalexiou, S.; Payre, P.; Roos, L.; Rousseau, D.; Schwemling, P.; Talby, M.; Adlung, S.; Assmann, R.; Bauer, C.; Blum, W.; Brown, D.; Cattaneo, P.; Dehning, B.; Dietl, H.; Dydak, F.; Frank, M.; Halley, A. W.; Jacobs, K.; Lauber, J.; Lütjens, G.; Lutz, G.; Männer, W.; Richter, R.; Schröder, J.; Schwarz, A. S.; Settles, R.; Seywerd, H.; Stierlin, U.; Stiegler, U.; St. Denis, R.; Wolf, G.; Alemany, R.; Boucrot, J.; Callot, O.; Cordier, A.; Davier, M.; Duflot, L.; Grivaz, J.-F.; Heusse, Ph.; Jaffe, D. E.; Janot, P.; Kim, D. W.; Le Diberder, F.; Lefrançois, J.; Lutz, A.-M.; Schune, M.-H.; Veillet, J.-J.; Videau, I.; Zhang, Z.; Abbaneo, D.; Bagliesi, G.; Batignani, G.; Bottigli, U.; Bozzi, C.; Calderini, G.; Carpinelli, M.; Ciocci, M. A.; Dell'Orso, R.; Ferrante, I.; Fidecaro, F.; Foà, L.; Forti, F.; Giassi, A.; Giorgi, M. A.; Gregorio, A.; Ligabue, F.; Lusiani, A.; Mannelli, E. B.; Marrocchesi, P. S.; Messineo, A.; Palla, F.; Rizzo, G.; Sanguinetti, G.; Spagnolo, P.; Steinberger, J.; Tenchini, R.; Tonelli, G.; Triggiani, G.; Vannini, C.; Venturi, A.; Verdini, P. G.; Walsh, J.; Betteridge, A. P.; Carter, J. M.; Gao, Y.; Green, M. G.; March, P. V.; Mir, Ll. M.; Medcalf, T.; Quazi, I. S.; Strong, J. A.; West, L. R.; Botterill, D. R.; Clifft, R. W.; Edgecock, T. R.; Norton, P. R.; Thompson, J. C.; Bloch-Devaux, B.; Colas, P.; Duarte, H.; Emery, S.; Kozanecki, W.; Lançon, E.; Lemaire, M. C.; Locci, E.; Marx, B.; Perez, P.; Rander, J.; Renardy, J.-F.; Rosowsky, A.; Roussarie, A.; Schuller, J.-P.; Schwindling, J.; Si Mohand, D.; Vallage, B.; Johnson, R. P.; Litke, A. M.; Taylor, G.; Wear, J.; Ashman, J. G.; Babbage, W.; Booth, C. N.; Buttar, C.; Cartwright, S.; Combley, F.; Dawson, I.; Thompson, L. F.; Barberio, E.; Böhrer, A.; Brandt, S.; Cowan, G.; Grupen, C.; Lutters, G.; Rivera, F.; Schäfer, U.; Smolik, L.; Bosisio, L.; Della Marina, R.; Giannini, G.; Gobbo, B.; Ragusa, F.; Bellantoni, L.; Chen, W.; Cinabro, D.; Conway, J. S.; Feng, Z.; Ferguson, D. P. S.; Gao, Y. S.; Grahl, J.; Harton, J. L.; LeClaire, B. W.; Lishka, C.; Pan, Y. B.; Saadi, Y.; Schmitt, M.; Sharma, V.; Shi, Z. H.; Walsh, A. M.; Weber, F. V.; Wu, Sau Lan; Wu, X.; Zheng, M.; Zobernig, G.
1993-07-01
In a sample of about 1.1 million hadronic Z decays recorded with the ALEPH detector during the 1990-1992 running of LEP, two unambiguous B S meson candidates were observed. From these events the mass of the B S meson has been measured to be 5.3686 ± 0.0056 (stat.) ± 0.0015 (syst.) GeV.
New-particle spectroscopy, quarkonium and gluonic mesons
Bloom, E.D.
1982-10-01
Recent experimental results on quarkonium and gluonic mesons are presented and discussed. Comparisons with theory are made. Quarkonium predictions seem to agree well with experiment. The question of the experimental verification of gluonic mesons is clouded by the difficulty of the theoretical interpretation.
Beauty vector meson decay constants from QCD sum rules
NASA Astrophysics Data System (ADS)
Lucha, Wolfgang; Melikhov, Dmitri; Simula, Silvano
2016-01-01
We present the outcomes of a very recent investigation of the decay constants of nonstrange and strange heavy-light beauty vector mesons, with special emphasis on the ratio of any such decay constant to the decay constant of the corresponding pseudoscalar meson, by means of Borel-transformed QCD sum rules. Our results suggest that both these ratios are below unity.
p ¯p annihilation into D ¯D meson pair within an effective Lagrangian model
NASA Astrophysics Data System (ADS)
Shyam, R.; Lenske, H.
2016-02-01
We study the charmed meson pair (D¯ 0D0 and D+D-) production in p ¯p annihilation within an effective Lagrangian model that has only the baryon-meson degrees of freedom and involves the physical hadron masses. The reaction amplitudes include terms corresponding to the t -channel Λc+, Σc+, and Σc++ baryon exchanges and the s -channel excitation, propagation and decay of the Ψ (3770 ) resonance into the charmed mesons. The initial- and final-state distortion effects have been accounted for by using a simple eikonal approximation-based procedure in the same way as was done in our previous study of the p ¯p →Λ¯c-Λc+ reaction within a similar model. The D¯0D0 production reaction is dominated by the Λc+ baryon exchange process and the corresponding total cross sections are predicted to be in the range of 0.18 -0.7 μ b for antiproton beam momenta varying between threshold and 20 GeV /c . The Ψ (3770 ) resonance contributions have a large influence on the differential cross sections of the D-D+ production reaction.
Rare B meson decays at the Tevatron
Hopkins, Walter; /Cornell U., Phys. Dept.
2011-08-01
Rare B meson decays are an excellent probe for beyond the Standard Model physics. Two very sensitive processes are the B{sub s,d}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and b {yields} s{mu}{sup +}{mu}{sup -} decays. We report recent results at a center of mass energy of {radical}s = 1.96 TeV from the CDF II and D0 collaborations using between 3.7 fb{sup -1} and 6.9 fb{sup -1} taken during Run II of the Fermilab Tevatron Collider.
Meson Photoproduction Experiments at ELPH, Tohoku University
NASA Astrophysics Data System (ADS)
Ishikawa, Takatsugu; Fujimura, Hisako; Fukasawa, Hiroshi; Hashimoto, Ryo; He, Qinghua; Honda, Yuki; Iwata, Takahiro; Kaida, Shun; Kasagi, Jirohta; Kawano, Atsushi; Kuwasaki, Shuzo; Maeda, Kazushige; Masumoto, Shin'ichi; Miyabe, Manabu; Miyahara, Fusashi; Mochizuki, Kei'ichi; Muramatsu, Norihito; Nakamura, Akihiko; Nawa, Ken'ichi; Ogushi, Shoei; Okada, Yasuyuki; Onodera, Yoshihito; Ozawa, Kyoichiro; Sakamoto, Yasunobu; Sato, Mamoru; Shimizu, Hajime; Sugai, Hiroyuki; Suzuki, Koutaku; Tajima, Yasuhisa; Takahashi, Shin'ichiro; Taniguchi, Yusuke; Tsuchikawa, Yusuke; Yamazaki, Hirohito; Yamazaki, Ryuji; Yoshida, Hiroshi Y.
Meson photoproduction experiments have been conducted with an electromagnetic (EM) calorimeter FOREST at Research Center for Electron Photon Science (ELPH), Tohoku University. A narrow resonance observed at W = 1670 MeV in η photoproduction on the neutron is of great interest, which is a candidate of an anti-decuplet pentaquark baryon although its origin is still controversial. The preliminary results of the cross sections for π0 and η photoproduction on the deuteron are presented. The next generation FOREST experiments have been planned to study S11(1535) properties in the nuclear medium by searching for η-mesic nucleus states. The planned experiments are also shown in this contribution.
Scalar Mesons, Multiquark States and Supersymmetry
Catto, Sultan
2008-08-31
Quark models with potentials derived from QCD, including the quark-diquark model for excited hadrons leading to a symmetry between mesons and baryons gives mass formulae in very good agreement with experiment and goes a long way in explaining the approximate symmetries and supersymmetries of the hadronic spectrum, including the symmetry breaking mechanism. We give a description of the only algebra describing color degrees of freedom based on split octonionic units and leading to a mathematical understanding of formation of diquarks as well as multiquark states.
Theoretical aspects of light meson spectroscopy
Barnes, T. |
1995-12-31
In this pedagogical review the authors discuss the theoretical understanding of light hadron spectroscopy in terms of QCD and the quark model. They begin with a summary of the known and surmised properties of QCD and confinement. Following this they review the nonrelativistic quark potential model for q{anti q} mesons and discuss the quarkonium spectrum and methods for identifying q{anti q} states. Finally, they review theoretical expectations for non-q{anti q} states (glueballs, hybrids and multiquark systems) and the status of experimental candidates for these states.
MESON CORRELATION FUNCTIONS AT HIGH TEMPERATURES.
WISSEL, S.; DATTA, S.; KARSCH, F.; LAERMANN, E.; SHCHEREDIN, S.
2005-07-25
We present preliminary results for the correlation- and spectral functions of different meson channels on the lattice. The main focus lies on gaining control over cut-off as well as on the finite-volume effects. Extrapolations of screening masses above the deconfining temperature are guided by the result of the free (T = {infinity}) case on the lattice and in the continuum. We study the quenched non-perturbatively improved Wilson-clover fermion as well as the hypercube fermion action which might show less cut-off effects.
Meson Production and Baryon Resonances at CLAS
Volker Burkert
2011-02-01
I give a brief overview of the exploration of baryon properties in meson photo- and electroproduction. These processes provide ample information for the study of electromagnetic couplings of baryon resonances and to search for states, yet to be discovered. The CLAS detector, combined with the use of energy-tagged polarized photons and polarized electrons, as well as polarized targets and the measurement of recoil polarization, provide the tools for a comprehensive nucleon resonance program. I briefly present the status of this program, prospects for the next few years, and plans for the Jefferson Lab 12 GeV upgrade.
Phenomenological Implications of the Nucleon's Meson Cloud
NASA Astrophysics Data System (ADS)
Hobbs, T. J.
2015-09-01
The long-distance structure of the interacting nucleon receives important contributions from its couplings to light hadronic degrees of freedom—a light meson cloud—while an analogous nonperturbative mechanism is expected to generate an intrinsic charm (IC) component to the proton wavefunction. We investigate both possibilities, keeping for the former a special eye to improving the theoretical understanding of the pion-nucleon vertex in light of proposed measurements. Regarding the latter possibility of IC, we highlight recent results obtained by a global QCD analysis of the light-front model proposed in Hobbs et al. (Phys Rev D 89:074008, 2014).
Charmed-strange mesons revisited: Mass spectra and strong decays
NASA Astrophysics Data System (ADS)
Song, Qin-Tao; Chen, Dian-Yong; Liu, Xiang; Matsuki, Takayuki
2015-03-01
Inspired by the present experimental status of charmed-strange mesons, we perform a systematic study of the charmed-strange meson family in which we calculate the mass spectra of the charmed-strange meson family by taking a screening effect into account in the Godfrey-Isgur model and investigate the corresponding strong decays via the quark pair creation model. These phenomenological analyses of charmed-strange mesons not only shed light on the features of the observed charmed-strange states, but also provide important information on future experimental search for the missing higher radial and orbital excitations in the charmed-strange meson family, which will be a valuable task in LHCb, the forthcoming Belle II, and PANDA.
Meson mass at real and imaginary chemical potentials
NASA Astrophysics Data System (ADS)
Kashiwa, Kouji; Matsuzaki, Masayuki; Kouno, Hiroaki; Sakai, Yuji; Yahiro, Masanobu
2009-04-01
Chemical-potential dependence of pi and sigma meson masses is analyzed at both real and imaginary chemical potentials, μR and μI, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model that possesses both the extended Z3 symmetry and chiral symmetry. In the μI region, the meson masses have the Roberge-Weiss periodicity. The μI dependence of the meson masses becomes stronger as temperature increases. We argue that meson masses and physical quantities in the μR region will be determined from lattice QCD data on meson masses in the μI region by using the PNJL model, if the data are measured in the future.
Probing the perturbative dynamics of exclusive meson pair production
NASA Astrophysics Data System (ADS)
Harland-Lang, L. A.; Khoze, V. A.; Ryskin, M. G.; Stirling, W. J.
2013-10-01
We present the results of a recent novel application of the 'hard exclusive' perturbative formalism to the process gg → MMbar at large angles, where M (Mbar) is a light meson (anti-meson). As well as discussing the important theoretical features of the relevant leading-order gg → qqbar (gg) qqbar (gg) 6-parton amplitudes, we also comment on their phenomenological implications. In particular, we consider the central exclusive production of meson pairs at comparatively large transverse momentum k⊥, which is expected to proceed via this mechanism. We show that this leads to various non-trivial predictions for a range of exclusive processes, and that the cross sections for the η‧ and η mesons display significant sensitivity to any valence gg component of the meson wavefunctions.
Meson mass at real and imaginary chemical potentials
Kashiwa, Kouji; Sakai, Yuji; Yahiro, Masanobu; Matsuzaki, Masayuki; Kouno, Hiroaki
2009-04-01
Chemical-potential dependence of pi and sigma meson masses is analyzed at both real and imaginary chemical potentials, {mu}{sub R} and {mu}{sub I}, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model that possesses both the extended Z{sub 3} symmetry and chiral symmetry. In the {mu}{sub I} region, the meson masses have the Roberge-Weiss periodicity. The {mu}{sub I} dependence of the meson masses becomes stronger as temperature increases. We argue that meson masses and physical quantities in the {mu}{sub R} region will be determined from lattice QCD data on meson masses in the {mu}{sub I} region by using the PNJL model, if the data are measured in the future.
QCD description of backward vector meson hard electroproduction
NASA Astrophysics Data System (ADS)
Pire, B.; Semenov-Tian-Shansky, K.; Szymanowski, L.
2015-05-01
We consider backward vector meson exclusive electroproduction off nucleons in the framework of collinear QCD factorization. Nucleon to vector meson transition distribution amplitudes (TDAs) arise as building blocks for the corresponding factorized amplitudes. In the near-backward kinematics, the suggested factorization mechanism results in the dominance of the transverse cross section of vector meson production (σT≫σL ) and in the characteristic 1 /Q8-scaling behavior of the cross section. We evaluate nucleon to vector meson TDAs in the cross-channel nucleon exchange model and present estimates of the differential cross section for backward ρ0, ω and ϕ meson production off protons. The resulting cross sections are shown to be measurable in the forthcoming JLab@12 GeV experiments.
Charmed Mesons in Nuclei with Heavy-Quark Spin Symmetry
NASA Astrophysics Data System (ADS)
Tolos, L.; Garcia-Recio, C.; Nieves, J.; Romanets, O.; Salcedo, L. L.
2013-08-01
We study the properties of charmed pseudoscalar and vector mesons in dense matter within a unitary meson-baryon coupled-channel model which incorporates heavy-quark spin symmetry. This is accomplished by extending the SU(3) Weinberg-Tomozawa Lagrangian to incorporate spin-flavor symmetry and implement a suitable flavor symmetry breaking. Several resonances with negative parity are generated dynamically by the s-wave interaction between pseudoscalar and vector meson multiplets with 1/2+ and 3/2+ baryons. Those states are then compared to experimental data as well as theoretical models. Next, Pauli-blocking effects and meson self-energies are introduced in a self-consistent manner to obtain the open-charm meson spectral functions in a dense nuclear environment. We finally discuss the formation of D-mesic nuclei.
Sharma, Neelesh; Verma, R. C.
2010-11-01
Two-body hadronic weak decays of B{sub c} meson emitting pseudoscalar and heavy scalar mesons are investigated using the Spectator Quark Model. Decay amplitudes are obtained using the factorization scheme; consequently, branching ratios are predicted in the Isgur-Scora-Grinstein-Wise (ISGW II) model.