arXiv subjects
Publications and source records attributed to Valery E. Lyubovitskij.
The two newly observed hidden-bottom mesons Zb(10610) and Zb'(10650) with quantum numbers J(P) = 1(+) are considered as hadronic molecules composed of BB(*) and B(*)B(*), respectively. We give predictions for the widths of the strong two-body decays Zb(+) to Upsilon(nS) + pi(+) and Zb'(+) to Upsilon(nS) + pi(+) in a phenomenological Lagrangian approach.
We present a detailed analysis of nucleon electromagnetic and axial form factors in a holographic soft-wall model. This approach is based on an action which describes hadrons with broken conformal invariance and incorporates confinement through the presence of a background dilaton field.For Nc=3 we describe the nucleon structure in a superposition of a three valence quark state with high Fock states including an adjustable number of partons (quarks, antiquarks and gluons) via studying the dynamics of 5D fermion fields of different scaling dimension in anti-de Sitter (ADS) space. According to the gauge/gravity duality the 5D fermion fields of different scaling dimension correspond to the Fock state components with a specific number of partons. In the present application we restrict to the contribution of 3, 4 and 5 parton components in the nucleon Fock state. With a minimal number of free parameters (dilaton scale parameter, mixing parameters of partial contributions of Fock states, coupling constants in the effective Lagrangian) we achieve a reasonable agreement with data for the nucleon form factors.
We extend the confined covariant constituent quark model that was previously developed by us for mesons to the baryon sector. In our numerical calculation we use the same values for the constituent quark masses and the infrared cutoff as have been previously used in the meson sector. In a first application we describe the static properties of the proton and neutron, and the $Λ$-hyperon (magnetic moments and charge radii) and the behavior of the nucleon form factors at low momentum transfers. We discuss in some detail the conservation of gauge invariance of the electromagnetic transition matrix elements in the presence of a nonlocal coupling of the baryons to the three constituent quark fields.
We use a matching procedure of sum rules relating the electromagnetic form factors to generalized parton distributions (GPDs) and AdS modes. In this way, in the framework of an AdS/QCD hard-wall model, the helicity-independent GPDs of quarks for the nucleon in the zero skewness case are calculated.
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. We show that in the case of the bound-state problem (hadronic mass spectrum) two versions of the model with a positive and negative dilaton profile are equivalent to each other by a special transformation of the bulk field. We also comment on recent works which discuss the dilaton sign in the context of soft-wall approaches.
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. Results obtained for heavy-light meson masses and decay constants are consistent with predictions of HQET. In the baryon sector applications to the baryon masses, nucleon electromagnetic form factors and generalized parton distributions are discussed.
We present the results of a systematic leading order calculation of hyperon Compton scattering and extract the forward spin polarizability gamma0 of hyperons within the framework of SU(3) heavy baryon chiral perturbation theory (HBChPT). The results obtained for gamma0 in the case of nucleons agree with that of the known results of SU(2) HBChPT when kaon loops are not considered.
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.
The experimental data on the processes $ππ\toππ,K\bar{K},ηη,ηη^\prime$ in the $I^GJ^{PC}=0^+0^{++}$ channel have been jointly analyzed to study the status and nature of the $f_0$. The method of analysis is based on analyticity and unitarity and uses an uniformization procedure. Some spectroscopic implications from results of the analysis are discussed.
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.
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.
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.
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
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.
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.
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.
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.
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.