The observation possibility of BcB_c excitations at LHC

It is shown that in the decays $B_c(2P)\to B_c^* \gamma^\mathrm{hard}$, $B_c(3P)\to B_c^* \gamma^\mathrm{hard}$ and $B_c(2S)\to B_c^* +\pi^+\pi^-$ followed by the decay $B_c^*\to B_c +\gamma^\mathrm{soft}$ the loss of the soft photon $\gamma^\mathrm{soft}$ do not wash out peaks from the initial excitations. The relative yields of $B_c^*$, 2P-wave, and 3P-wave states of $B_c$ meson at LHC are estimated as function of transverse energy of emitted photon $\gamma^\mathrm{hard}$. It is pointed out, that the decays $B_c(2S) \to B_c(B_c^*)+\pi^+\pi^-$ could provide a new information about a $\sigma$ resonance nature.Comment: The talk given at the XIth International Workshop High Energy Physics and Quantum Field Theory, June 24- June 30, 2013, Saint Petersburg, Russia; to be published in PoS; 8 pages, 3 figure

Double Charmonia Production in Exclusive ZZ Boson Decays

This article is devoted to systematic analysis of double charmonium production in exclusive $Z$ boson decays in the framework of Nonrelativistic Quantum Chromodynamic (NRQCD) and leading twist light-cone (LC) models. Theoretical predictions for branching fractions of all considered decays are presented. According to obtained results in the case of allowed by helicity suppression rule processes the effect of internal quark motion increases the branching fraction by a factor 1.5, while for forbidden reactions LC predictions are strictly zero, while NRQCD ones are significantly smaller than for allowed.Comment: 10 pages, 2 figures, 2 tables. arXiv admin note: substantial text overlap with arXiv:1706.0409

The contribution of the hadronic component of the photon into the D∗D^*-meson photoproduction at HERA

In the framework of the vector dominance model (VDM) new contribution into the cross-section of $D^*$-meson photoproduction at HERA has been estimated. This contribution is due to the interaction of the virtual vector $c\bar c$-mesons from photon with the proton. It has been shown that the mechanism under discussion plays the essential role for all values of transverse momentum of $D^*$-mesons at HERA. Taking into account for the contribution of this mechanism improves the description of the experimental cross section distribution.Comment: 12 pages, LATEX file, 5 ps-figures; changed LATEX style; estimated the model uncertaint

Charge asymmetry in the photonic production of charmed mesons

Charge asymmetries for the charm meson production ($D^{*+}$--$D^{*-}$, $D^{*0}$--$\bar D^{*0}$ and $D^+_s$--$\bar D^-_s$) have been estimated for the COMPASS kinematic conditions in the framework of perturbative recombination model. Mass corrections have been taken into account in the calculations. The large asymmetry for $D^+_s$--$\bar D^-_s$ production has been predicted.Comment: 15 pages, 6 figures, ReVTeX, submitted to Phys. Atom. Nucl. in February 200

Light hadron production in Bc→J/ψ+XB_c \to J/\psi+X decays

Decays of ground state $B_{c}$-meson $B_{c}\to J/\psi+n\pi$ are considered. Using existing parametrizations for $B_{c}\to J/\psi$ form-factors and $W^{*}\to n\pi$ spectral functions we calculate branching fractions and transferred momentum distributions of $B_{c}\to J/\psi+n\pi$ decays for $n=1,2,3,4$. Inclusive decays $B_{c}\to J/\psi+\bar{u}d$ and polarization asymmetries of final charmonium are also investigated. Presented in our article results can be used to study form-factors of $B_{c}\to J/\psi$ transitions, $\pi$-meson system spectral functions and give the opportunity to check the factorization theorem.Comment: minor changes, published in Phys.Rev.

Charmonium production in hadronic experiments at the energy 70 GeV

The production of the charmonium states in hadronic experiments is considered in NLO at the strong coupling constant. It is shown, that such an approach solves some significant problems, arising when only leading order processes are considered. In particular, in such a consideration distributions over the transverse momentum of the final charmonium can be obtained. There appears also a natural explanation to the existence of $\chi_{c1}$-meson in final state, that is observed experimentally and cannot be produced in leading order processes.Comment: 28 pages, 13 figure

Associative production of Υ\Upsilon and open charm at LHC

The yield of $\Upsilon$ associated with open charm has been estimated with different approaches. The crucial differences between SPS and DPS predictions are discussed.Comment: 6 pages, 5 figure

Lifetimes of doubly heavy baryons

We perform a detailed investigation of total lifetimes for the doubly heavy baryons $\Xi_{QQ'}$, $\Omega_{QQ'}$ in the framework of operator product expansion over the inverse heavy quark mass, whereas, to estimate matrix elements of operators obtained in OPE, approximations of nonrelativistic QCD are used.Comment: 21 pages, 9 figure

The charm contribution into the proton structure function in DIS at the HERA ep-collider

In the framework of perturbative QCD and a model for the production of charmed hadrons the structure function $F^c_2$ is calculated and compared with the experimental data of H1 and ZEUS Collaborations. We show that the spectator mechanism of the $D^*$-meson production independent of a hadronic remnant is valid at $p_T>10$ GeV, only. We find that the evolution of $F^c_2(x,Q^2)$ versus the virtuality $Q^2$ can be neglected in the kinematic region of HERA.Comment: 21 pages, 9 figure

The relative yields of heavy hadrons as function of transverse momentum at LHC experiments

It is shown that the dependence of ratio $f_s/f_d$ could be understood within the fragmentation approach. However, the validity of fragmentation model is questionable at low $p_T$, and contributions of nonfragmentation mechanisms are possible. It is demonstrated, that the precise measurements of $p_T$ dependence of $f_s/f_d$, $f_{\Lambda_b}/f_{B}$ and analogous values as function of $p_T$ can essentially improve our understanding of heavy hadron production.At large $p_T$ a plateau is expected in $f_s/f_d$ distribution. Contrary, a plateau is not expected in $f_{B_c}/f_{B}$ distribution on $p_T$.Comment: 15 pages, 10 figures, revtex4, $f_{B_c}/f_{B}$ has been estimated for the LHCb fiducial regio