arXiv subjects
Publications and source records attributed to A. V. Luchinsky.
The paper is devoted to investigation of $K$ mesons production in exclusive $B_{c}$ decays $B_{c} \to ψ^{(')}K^{+}K^{-}π^{+}$ and $B_{c} \to ψ^{(')}K^{+}π^{+}π^{-}$. In the framework of resonance approximation we obtain theoretical predictions for branching fractions of these decays and present distributions over different kinematical variables.
This report is devoted to the analytical calculation of heavy quarkonia production processes in modern experiments such as LHC, B-factories and superB-factories in computer. Theoretical description of heavy quarkonia is based on the factorization theorem. This theorem leads to special structure of the production amplitudes which can be used to develop computer algorithm which calculates these amplitudes automatically. This report is devoted to the description of this algorithm. As an example of its application we present the results of the calculation of double charmonia production in bottomonia decays and inclusive the $χ_{cJ}$ mesons production in pp-collisions.
Hadronic production of $P$-wave charmonium states $χ_{cJ}$ in hadronic interaction is considered. Using experimental results of CDF and LHCb collaborations we show, that contributions of color-singlet components are dominant. As for color-octet mechanism, we show, that contributions from $P$-wave states can also be observed, while $S$-wave states can be neglected. The best experimental observables that give information about relative importance of color-singlet and color-octet components are the ratios $χ_{c2}/χ_{c1}$ and $χ_{c0}/χ_{c1}$.
In the present paper, we discuss the $P$-wave bottomonium production within the both color octet and color singlet models in NLO at LHC energies. We calculate the production and the transverse momentum distributions of the $χ_{1,2b}$ states. We found, that the ratios of bottomonium and charmonium spin states are fundamentally complementary at different $p_T$ scales. We give predictions for the ratio of the $n=2$ and $n=1$ radial excitations production cross sections.
The paper is devoted to vector or pseudoscalar heavy quarkonia production J/ψ, ψ(2S), B_{s} or B_s^* in association with five charged π-mesons in exclusive B_c-meson decays. Using available formfactors parameterizations and spectral functions of $W \to 5 π$ transition we obtain branching fractions of these decays and distributions over invariant mass of (5π)-system.
This paper is devoted to the leading twist exclusive bottomonia decays with double charmonium in the final state. Using models of the twist-2 charmonia distribution amplitudes the widths of these decays are calculated within light cone formalism. In addition, the processes under consideration are studied within nonrelativistic QCD. In our analysis we have found that the production of some of the $P$-wave charmonia mesons with $L_z \neq 0$ is allowed already at the leading twist approximation. This means that the selection rules which predict the suppression of such decays are violated. The mechanism which lies behind this violation is discussed.
Theoretical predictions of cross sections and properties of the $J/ψ$-meson production in association with an open charm hadron and formation of two open charm hadrons from two $c\bar{c}$ pairs in the LHC conditions are presented. Processes in both single and in double parton scattering mechanisms are included into consideration. Special attention is paid to the kinematic limits of the LHCb detector for which comparison with the newest experimental data is carried out.
The production of the charmonium states in proton-antiproton experiments is considered at the energy rates near threshold in NLO. Such a consideration allows one to obtain non zero distributions over the transverse momentum of the final charmonium and gives a natural explanation to the existence of $χ_{c1}$-meson in final state, that is observed experimentally and cannot be produced in leading order processes. The crucial role of scale parameter choice in $α_s (Q^2)$ and partonic distributions $f(x,Q^2)$ shown, and the correct choice offered.
The Bc -> J/psi(Bs,Bs*)+ n pi decay amplitudes are calculated in the frame work of factorization model, which allows to represent this processes as Bc decay into J/psi Bs+W* followed by the virtual W*-boson decay into the final set of pi mesons. The module for the generation of Bc meson decays into J/psi + n pi and Bs(*) + n pi (n <= 3) is implemented into the GAUSS program package of the LHCb Collaboration.
In the current work spectroscopy and possibility of observation at the LHC of tetraquarks composed of 4 heavy quarks is discussed. Tetraquarks concerned are T_{4c}=[cc][cc]$, T_{4b}=[bb][bb] and T_{2[bc]}=[bc][bc]. By solving nonrelativistic Schroedinger equation masses of these states are found with the hyperfine splitting accounted for. It is shown that masses of tensor tetraquarks T_{4c}(2++) and T_{2[bc]}(2++) are high enough to observe these states as peaks in the invariant mass distributions of heavy quarkonia pairs in pp -> T_{4c}+X -> 2J/ψ+X, pp -> T_{2[bc]}+X -> 2B_{c}+X and pp -> T_{2[bc]}+X -> J/ψΥ(1S)+X channels while T_{4b} is under the threshold of decay into a vector bottomonia pair.
The article is devoted to double J/psi-meson production at LHC. Theoretical predictions for pp -> 2J/psi+X cross section at sqrt{s}=7 TeV for different kinematical restrictions are presented. Special attention is payed to possible contribution of novel particles -- tetraquarks build from four c-quarks. According to presented in our article estimates, it is quietly possible to observe at least one of these state (tensor meson) experimentally.
The module for the generation of $B_c$ meson decays into $J/ψ+ nπ$ and $B_s^{(*)} + nπ$ ($n\le 4$) is implemented into EvtGen program package. The decay amplitudes are calculated in the frame work of factorization model. Within this approach the decay can be represented as $B_c$ decay into $J/ψ(B_s)+W^*$ followed by the virtual $W^*$-boson decay into the final set of $π$-mesons. The described calculation technique allows to adopt the parameters of $W^*\to nπ$ transition from the analysis of $τ$ decay into $ν_τ+nπ$. Comparison with available theoretical predictions is performed.
The inclusive production of light mesons in pp-scattering is considered in the framework of reggeon phenomenology with supercritical Pomeron. Available low-energy data can be explained with three reggeon particles taken into account. With the obtained results rapidity and pseudorapidity distributions for light-meson production at LHC energies are predicted.
The article is devoted to Bc->Bs+n pi, Bc->Bs*+n pi decays with n=1, 2, 3, 4. In the framework of factorization theorem the branching fractions of these processes can be written as convolution of hard part, describing Bc->Bs W, Bc->Bs* W vertices, and spectral functions, that correspond to transition of virtual $W$-boson into a final pi-meson system. These functions were obtained from the fit of experimental data on $τ$-lepton decay and electron-positron annihilation. Using different sets of Bc->Bs decay form-factors we present branching fractions and distributions over the invariant mass of the final pi-meson system.
The decays $η'\to3π^{0}$ and $π^{0}π^{+}π^{-}$ were consider in isobar model approach. Branching ratio and Dalitz-plot shape of the decay $η'\to3π^{0}$ can be explain by $a0$- and $σ$-meson contributions. The $σ$ meson term is needed for the Dalitz-plot distribution reconstruction. The branching ratio of the decay $η'\to π^{0}π^{+}π^{-}$ can be calculated in the same isobar framework. The prediction for the Dalitz-plot of this decay is shown which strongly dependents from model parameters.
Decays of ground state $B_{c}$-meson $B_{c}\to J/ψ+nπ$ are considered. Using existing parametrizations for $B_{c}\to J/ψ$ form-factors and $W^{*}\to nπ$ spectral functions we calculate branching fractions and transferred momentum distributions of $B_{c}\to J/ψ+nπ$ decays for $n=1,2,3,4$. Inclusive decays $B_{c}\to J/ψ+\bar{u}d$ and polarization asymmetries of final charmonium are also investigated. Presented in our article results can be used to study form-factors of $B_{c}\to J/ψ$ transitions, $π$-meson system spectral functions and give the opportunity to check the factorization theorem.
The decay $η'\toηπ^{0}π^{0}$ is studied in the framework of isobar model. It is shown, that good agreement with the experiment is achieved if $a_0$- and $σ$-meson contributions are taken into account. The contribution of $a_0$-meson is dominant, but $σ$-meson is necessary to reproduce the form of experimental Dalitz plot. Instead of usual Breit-Wigner form of $σ$-meson propagator we use parametrization of $ππ$-amplitude, that satisfies analiticity, crossing, unitarity and chirality constraints. This amplitude has a pole in complex plane, that corresponds to $σ$-meson and describe experimental data on $ππ$-scattering in $K_{e4}$ decay.
This paper is devoted to the study of the leading twist distribution amplitudes of P-wave nonrelativistic mesons. It is shown that at the leading order approximation in relative velocity of quark-antiquark pair inside the mesons these distribution amplitudes can be expressed through one universal function. As an example, the distribution amplitudes of the P-wave charmonia mesons are considered. Within QCD sum rules the model for the universal function of P-wave charmonia mesons is built. In addition, it is found the relations between the moments of the universal function and the nonrelativistic QCD matrix elements that control relativistic corrections to any amplitude involving P-wave charmonia. Our calculation shows that characteristic size of these corrections is of order of ~30 %.