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Valery E. Lyubovitskij

Publications and source records attributed to Valery E. Lyubovitskij.

At least 145 records · Page 8Linked to original sources
arXiv2010

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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arXiv2010

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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arXiv2010

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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arXiv2010

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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arXiv2010

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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arXiv2010

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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arXiv2010

Lepton flavor violating decays of vector mesons

We estimate the rates of lepton flavor violating decays of the vector mesons $ρ, ω, ϕ\to e μ$. 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 (\Lfv). The effective lepton-vector meson couplings are extracted from the existing experimental bounds on the nuclear $μ^--e^-$ conversion. In particular, we derive an upper limit for the \Lfv branching ratio ${\rm Br}(ϕ\to e μ) \leq1.3 \times 10^{-21}$ which is much more stringent than the recent experimental result ${\rm Br}(ϕ\to e μ) < 2 \times 10^{-6}$ presented by the SND Collaboration. Very tiny limits on \Lfv decays of vector mesons derived in this letter make direct experimental observation of these processes unrealistic.

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arXiv2010

Relativistic constituent quark model with infrared confinement

We refine the relativistic constituent quark model developed in our previous papers to include the confinement of quarks. It is done, first, by introducing the scale integration in the space of alpha-parameters, and, second, by cutting this scale integration on the upper limit which corresponds to an infrared cutoff. In this manner one removes all possible thresholds presented in the initial quark diagram. The cutoff parameter is taken to be the same for all physical processes. We adjust other model parameters by fitting the calculated quantities of the basic physical processes to available experimental data. As an application, we calculate the electromagnetic form factors of the pion and the transition form factors of the omega and eta Dalitz decays.

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arXiv2010

Meson wave function from holographic approaches

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

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arXiv2010

Quasielastic rho0 electroproduction on the proton at intermediate energy: Role of scalar and pseudoscalar meson exchange

We present a detailed analysis of rho(0) electroproduction at intermediate energy for quasi-elastic knockout kinematics. The approach is based on an effective Lagrangian which generates exchanges of scalar, pseudoscalar, axial-vector and tensor mesons. The specific role of mesons with different values for J(PC) is analyzed. We show that the pi(0) exchange amplitude and its interference terms with eta(eta') and f1 exchanges dominate in the transverse part of the cross section sigmaT. The main role plays the pi(0) to rho(0) M1 spin transition when coupling the virtual photons to the nucleon. In contrast, the longitudinal cross section sigmaL is generated by a series of scalar meson exchanges. To extract the dominant term more detailed information on the inner structure of scalar mesons is required. It turns out that recent data of the CLAS Collaboration on sigmaL and sigmaT can be described with reasonable accuracy if one proposes the quarkonium structure for the heavy scalar mesons (M > 1.3 GeV). On this basis the differential cross sections dsigmaL/dt and dsigmaT/dt are calculated and compared with the latest CLAS data.

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arXiv2010

Possible hadronic molecule structure of the Y(3940) and Y(4140)

In the present article we report on evidence for hadronic molecule structures in the charmonium sector. In particular we discuss the Y(3940) and the recently observed Y(4140) as heavy hadron molecule states with quantum numbers $J^{PC} = 0^{++}$ or $2^{++}$. The Y(3940) state is considered to be a superposition of $D^{\ast +}D^{\ast -}$ and $D^{\ast 0} \overline{D^{\ast 0}}$, while the Y(4140) is a bound state of $D_s^{\ast +}$ and $D_s^{\ast -}$ mesons. We give predictions for both the strong Y(3940) to J/psi omega, Y(4140) to J/psi phi and radiative Y(3940)/Y(4140) to gamma gamma decay widths in a phenomenological Lagrangian approach. The results for the strong hidden charm decay modes clearly support the molecular interpretation of the Y(3940) and Y(4140), while our estimates for the radiative decays provide a sensitive test for the underlying meson structure of the two Y mesons discussed here. The alternative assignment of $J^{PC} = 2^{++}$ is also tested, giving similar results for the strong decay widths.

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arXiv2010

Hadron Molecules

We discuss a possible interpretation of the open charm mesons $D_{s0}^*(2317)$, $D_{s1}(2460)$ and the hidden charm mesons X(3872), Y(3940) and Y(4140) as hadron molecules. Using a phenomenological Lagrangian approach we review the strong and radiative decays of the $D_{s0}^* (2317)$ and $D_{s1}(2460)$ states. The X(3872) is assumed to consist dominantly of molecular hadronic components with an additional small admixture of a charmonium configuration. Determing the radiative ($γJ/ψ$ and $γψ(2s)$) and strong ($J/ψ2π$ and $ J/ψ3π$) decay modes we show that present experimental observation is consistent with the molecular structure assumption of the X(3872). Finally we give evidence for molecular interpretations of the Y(3940) and Y(4140) related to the observed strong decay modes $J/ψ+ ω$ or $J/ψ+ ϕ$, respectively.

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arXiv2010

Strong two-body decays of the Lambdac(2940)+ in a hadronic molecule picture

The Lambdac(2940)+ baryon with possible quantum numbers J(P) = 1/2+ and 1/2- is studied as a molecular state composed of a nucleon and D* meson. We give predictions for the strong two-body decay channels Lambdac(2940)+ to p D0, Sigmac(++) pi(-) and Sigmac(0) pi(+) where the sum of partial widths is consistent with current data for the case of J(P) = 1/2(+). The case of J(P) = 1/2(-) is shown to be ruled out.

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arXiv2009

X(3872) as a molecular DD* state in a potential model

We discuss the possibility that the X(3872) can be a hadronic DD* bound state in the framework of a potential model. The potential is generated by the exchange of pseudoscalar, scalar and vector mesons resulting from the Lagrangian of heavy hadron chiral perturbation theory. The hadronic bound state configuration contains charged and neutral DD* components, while orbital S- and D-waves are included. Isospin symmetry breaking effects are fully taken into account. We show that binding in the DD* system with J(PC)=1(++) already exists for a reasonable value of the meson-exchange regularization parameter of Lambda around 1.2 GeV. We also explore the possibility of hadronic BB* bound states and show that binding can be achieved in the isoscalar limit for J(PC)=1(++) or 1(+-).

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arXiv2009

Hadronic molecule structure of the Y(3940) and Y(4140)

We report on further evidence that the Y(3940) and the recently observed Y(4140) are heavy hadron molecule states with quantum numbers J(PC) = 0(++). The Y(3940) state is considered to be a superposition of D*(+)D*(-) and D*(0) barD*(0), while the Y(4140) is a bound state of Ds*(+) and Ds*(-) mesons. For the first time we give predictions for the strong Y(3940) to Jpsi omega, Y(4140) to Jpsi phi and radiative Y(3940)/Y(4140) to gamma gamma decay widths in a phenomenological Lagrangian approach. Results for the strong Jpsi V (V = omega, phi) decays clearly support the molecular interpretation of the Y(3940) and Y(4140).

hep-ph↗
arXiv2009

Semileptonic decays of double heavy baryons in a relativistic constituent three-quark model

We study the semileptonic decays of double heavy baryons using a manifestly Lorentz covariant constituent three-quark model. We present complete results on transition form factors between double-heavy baryons for finite values of the heavy quark/baryon masses and in the heavy quark symmetry limit which is valid at and close to zero recoil. Decay rates are calculated and compared to each other in the full theory, keeping masses finite, and also in the heavy quark limit.

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