Nucleon Generalized Parton Distributions and Holographic Models
Using ideas from Light Front Holography, we discuss the calculation of the nucleon helicity-independent generalized parton distributions of quarks in the zero skewness case.
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arXiv subjects
Thomas Gutsche
Publications and source records attributed to Thomas Gutsche.
phi-meson production in proton-antiproton annihilation
Apparent channel-dependent violations of the OZI rule in nucleon-antinucleon annihilation reactions are discussed in the presence of an intrinsic strangeness component in the nucleon. Admixture of strange-antistrange quark pairs in the nucleon wave function enables the direct coupling to the phi-meson in the annihilation channel without violating the OZI rule. Three forms are considered in this work for the strangeness content of the proton wave function, namely, the uud cluster with a strange-antistrange sea quark component, kaon-hyperon clusters based on a simple chiral quark model, and the pentaquark picture. Nonrelativistic quark model calculations reveal that the strangeness magnetic moment and the strangeness contribution to the proton spin from the first two models are consistent with recent experimental data. For the third model, the uuds subsystem with the configurations FS[31]F[211]S[22] and FS[31]F[31]S[22] leads to negative values for the strangeness magnetic moment and the strangeness contribution to the proton spin. With effective quark line diagrams incorporating the 3P0 quark model we give estimates for the branching ratios of the proton-antiproton annihilation reactions at rest to two mesons. Results for the branching ratios of phi-meson production from atomic proton-antiproton s-wave states are for the first and third model found to be strongly channel dependent, in good agreement with measured rates.
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Mesons and baryons in the holographic soft-wall model
Mesons and baryons are considered in soft-wall holographic approach based on the correspondence of string theory in AdS space and conformal field theory in physical space-time. The model generates Regge trajectories linear in n and J (L) for the hadronic mass spectrum. Results obtained for heavy-light meson masses and decay constants are consistent with predictions of HQET. In the baryon sector applications to the nucleon electromagnetic form factors and generalized parton distributions are discussed.
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Mesons and baryons in a soft-wall holographic approach
We discuss a holographic soft-wall model developed for the description of mesons and baryons with adjustable quantum numbers n, J, L, S. This approach is based on an action which describes hadrons with broken conformal invariance and which incorporates confinement through the presence of a background dilaton field.
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Some Hadronic Properties from Light Front Holography
Using ideas from Light Front Holography, we discuss the calculation of hadronic properties. In this talk I will pay special attention to hadronic masses and the nucleon helicity-independent generalized parton distributions of quarks in the zero skewness case
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New bounds on lepton flavor violating decays of vector mesons and the Z0 boson
We give an estimate for the upper bounds on rates of lepton flavor violating (LFV) decays M to mu(pm) + e(mp) of vector mesons M = rho0, omega, phi, J/psi, Upsilon and the Z0 boson in a model independent way, analyzing the corresponding lowest dimension effective operators. These operators also contribute to nuclear mu-e-conversion. Based on this observation and using the existing experimental limits on this LFV nuclear process, we show that the studied two-body LFV decays of vector bosons are strongly suppressed independent on the explicit realization of new physics. The upper limits on the rates of some of these decays are significantly more stringent than similar limits known in the literature. In view of these results experimental observation of the two-body LFV decays of vector bosons looks presently unrealistic.
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Hadronic and radiative three-body decays of J/psi involving the scalars f0(1370), f0(1500) and f0(1710)
We study the role of the scalar resonances f0(1370), f0(1500) and f0(1710) in the strong and radiative three-body decays of J/psi with J/psi to V + P P (gamma gamma) and J/psi to gamma + P P (V V), where P (V) denotes a pseudoscalar (vector) meson. We assume that the scalars result from a glueball-quarkonium mixing scheme while the dynamics of the transition process is described in an effective chiral Lagrangian approach. Present data on J/psi to V + P P are well reproduced, predictions for the radiative processes serve as further tests of this scenario.
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Electroproduction of the Roper resonance on the proton: the role of the three-quark core and the molecular N-sigma component
The Roper resonance is considered as a mixed state of a three-quark core configuration and a hadron molecular component N+sigma. Based on this ansatz we study electroproduction of the Roper resonance. The strong and electromagnetic couplings induced by the quark core are calculated in the 3P0 model. The contribution of the vector meson cloud to the electromagnetic transition is given in the framework of the VMD model. Results are compared with the recent JLab electroproduction data.
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Strong three-body decays of Lambdac(2940)+
The Lambdac(2940)+ baryon with quantum numbers J(P) = 1/2(+) is considered as a hadronic molecule composed of a nucleon and D* meson. We give predictions for the width of the strong three-body decay processes Lambdac(2940)+ to Lambdac(2286)+ pi(+) pi(-) and Lambdac(2940)+ to Lambdac(2286)+ pi(0) pi(0) in this interpretation. Upcoming experimental facilities like a Super B factory at KEK or LHCb might be able to provide data on these decay modes.
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Generalized parton distributions in AdS/QCD
The nucleon helicity-independent generalized parton distributions (GPDs) of quarks are calculated in the zero skewness case, in the framework of the AdS/QCD model. The present approach is based on a matching procedure of sum rules relating the electromagnetic form factors to GPDs and AdS modes.
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J/psi gamma and psi(2S) gamma decay modes of the X(3872)
The X(3872) with quantum numbers J(PC) = 1(++) is considered as a composite state containing both molecular hadronic and a c bar(c) component. Based on this structure assumption we first constrain model parameters in order to reproduce the predictions for the radiative decay widths of X(3872) to J/psi gamma and X(3872) to psi(2S) gamma as obtained in c bar(c) potential models. Depending on these predictions we find that further inclusion of the molecular component can in principle lead to an improved description of the radiative X(3872) decays. We also show that strong decay modes of the X(3872) and in particular the ratio of radiative (J/psi gamma) to strong (J/psi pi(+) pi(-)) decays hint towards a subleading role of the c bar(c) component in the X(3872).
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Light and heavy mesons in a soft-wall holographic approach
We study the mass spectrum and decay constants of light and heavy mesons in a soft-wall holographic approach, using the correspondence of string theory in Anti-de Sitter space and conformal field theory in physical space-time.
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B_s(d) - bar B_s(d) mixing constraints on flavor changing decays of t and b quarks
We study those dimension 6 effective operators which generate flavor-changing quark-gluon transitions of the third generation quarks, with t -> g + u(c) and b -> g + d(s), and which could be of interest for LHC experiments. We analyze the contribution of these operators to B_s(d) - bar B_s(d) mixing and derive limits on the corresponding effective couplings from the existing experimental data. The Standard Model gauge invariance relates these couplings to the couplings controlling t -> g + u(c). On this basis we derive upper limits for the branching ratios of these processes. We further show that forthcoming LHC experiments might be able to probe the studied operators and the physics beyond the Standard Model related to them.
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Hidden-charm and radiative decays of the Z(4430) as a hadronic D_1 \bar{D^\ast} bound state
We study the $Z^\pm(4430)$ meson within a heavy hadron molecule interpretation where the $Z$ is considered as a bound state of a vector $D^\ast(2010)$ and an axial-vector $D_1(2420)$. We give predictions for the strong hidden-charm $Z^\pm(4430) \to π^\pm ψ$ and $π^\pmψ^\prime$ decay widths and also study the radiative $Z^\pm\;(J^P=1^-) \to π^\pmγ$ decay properties in a phenomenological Lagrangian approach. Our findings are qualitatively in line with the experimental observation that the $π^\pmψ^\prime$ transition dominates over the $π^\pmψ$ decay mode despite a smaller phase space. The width for the radiative mode $π^\pmγ$ is sizable, allowing possible detection in future experiments.
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Radiative decay of Lambdac(2940)+ in a hadronic molecule picture
The Lambdac(2940)+ baryon with quantum numbers J(P) = 1/2(+) is considered as a molecular state composed of a nucleon and D* meson. We give predictions for the width of the radiative decay process Lambdac(2940)+ to Lambdac(2286)+ gamma in this interpretation. Based on our results we argue that an experimental determination of the radiative decay width of Lambdac(2940)+ is important for the understanding of its intrinsic properties.
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Two-photon decay of heavy hadron molecules
We discuss the two-photon decay width of heavy hadron molecules and study the dependence on the constituent meson masses and on the binding energy. In addition finite size effects due to the extended structure of the bound state are shown to have a strong influence on the predictions for this decay width.
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Radiative decays of double heavy baryons in a relativistic constituent three-quark model including hyperfine mixing
We study flavor-conserving radiative decays of double heavy baryons using a manifestly Lorentz covariant constituent three-quark model. Decay rates are calculated and compared to each other in the full theory, keeping masses finite, and also in the heavy quark limit. We discuss in some detail hyperfine mixing effects.
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Charmed baryon Sigmac(2800) as a ND hadronic molecule
The isotriplet Sigmac(2800) baryon with possible quantum numbers J(P) = 1/2(+), 1/2(-) or 3/2(+), 3/2(-) is considered as a hadronic molecule composed of a nucleon and a D meson. We determine the strong two-body decay widths Sigmac to Lambdac + pi which are shown to be consistent with current data for the J(P) = 1/2(+) and J(P) = 3/2(-) assignments.
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