Prompt ηc\eta_c meson production at the LHC in the NRQCD with kTk_T-factorization

In the framework of the $k_T$-factorization, the prompt production of $\eta_c$ mesons at the LHC conditions is studied. Our consideration is based on the off-shell amplitudes for hard partonic subprocesses and on the nonrelativistic QCD (NRQCD) formalism for the formation of bound states. We try two latest parametrizations for noncollinear, or transverse momentum dependent (TMD) gluon densities derived from the Catani-Ciafaloni-Fiorani-Marchesini (CCFM) equation. We use the values of the nonperturbative matrix elements obtained from a combined fit of the $\eta_c$ and $J/\psi$ differential cross sections. Finally, we show an universal set of parameters that provides a reasonable simultaneous description for all of the available data on the prompt $J/\psi$ and $\eta_c$ production at the LHC.Comment: 5 pages, 2 figures, 3 table

Prompt charmonia production and polarization at LHC in the NRQCD with kTk_T-factorization. Part III: J/ψJ/\psi meson

In the framework of $k_T$-factorization approach, the production and polarization of prompt $J/\psi$ mesons at the LHC energies is studied. Our consideration is based on the non-relativistic QCD formalism for bound states and off-shell amplitudes for hard partonic subprocesses. Both the direct production mechanism and feed-down contributions from $\chi_c$ and $\psi(2S)$ decays are taken into account. The transverse momentum dependent (or unintegrated) gluon densities in a proton were derived from Ciafaloni-Catani-Fiorani-Marchesini evolution equation or, alternatively, were chosen in accordance with Kimber-Martin-Ryskin prescription. The non-perturbative color-octet matrix elements were first deduced from the fits to the latest CMS data on $J/\psi$ transverse momentum distributions and then applied to describe the ATLAS and LHCb data on $J/\psi$ production and polarization at $\sqrt s = 7$, $8$ and $13$ TeV. We perform an estimation of polarization parameters $\lambda_\theta$, $\lambda_\phi$ and $\lambda_{\theta \phi}$ which determine $J/\psi$ spin density matrix and demonstrate that treating the soft gluon emission as a series of explicit color-electric dipole transitions within NRQCD leads to unpolarized $J/\psi$ production at high transverse momenta, that is in qualitative agreement with the LHC data.Comment: 23 pages, 14 figures. arXiv admin note: substantial text overlap with arXiv:1508.0548

First estimates of the BcB_c wave function from the data on the BcB_c production cross section

In the framework of perturbative QCD and nonrelativistic bound state formalism, we calculate the production of $B_c$ and $B_c^*$ mesons at the conditions of the CDF and LHCb experiments. We derive first estimations for the $B_c$ wave function from a comparison with the available data.Comment: 3 pages, 1 figur

On perturbations of the isometric semigroup of shifts on the semiaxis

We study perturbations $(\tilde\tau_t)_{t\ge 0}$ of the semigroup of shifts $(\tau_t)_{t\ge 0}$ on $L^2(\R_+)$ with the property that $\tilde\tau_t - \tau_t$ belongs to a certain Schatten-von Neumann class \gS_p with $p\ge 1$. We show that, for the unitary component in the Wold-Kolmogorov decomposition of the cogenerator of the semigroup $(\tilde\tau_t)_{t\ge 0}$, {\it any singular} spectral type may be achieved by \gS_1 perturbations. We provide an explicit construction for a perturbation with a given spectral type based on the theory of model spaces of the Hardy space $H^2$. Also we show that we may obtain {\it any} prescribed spectral type for the unitary component of the perturbed semigroup by a perturbation from the class \gS_p with $p>1$

Particle Event Generator: A Simple-in-Use System PEGASUS version 1.0

PEGASUS is a parton-level Monte-Carlo event generator designed to calculate cross sections for a wide range of hard QCD processes at high energy $pp$ and $p\bar p$ collisions, which incorporates the dynamics of transverse momentum dependent (TMD) parton distributions in a proton. Being supplemented with off-shell production amplitudes for a number of partonic subprocesses and provided with necessary TMD gluon density functions, it produces weighted or unweighted event records which can be saved as a plain data file or a file in a commonly used Les Houches Event format. A distinctive feature of PEGASUS is an intuitive and extremely user friendly interface, allowing one to easily implement various kinematical cuts into the calculations. Results can be also presented "on the fly" with built-in tool \textsc{pegasus plotter}. A short theoretical basis is presented and detailed program description is given.Comment: 24 pages, 8 figure

Omega_{ccc} production via fragmentation at LHC

In the framework of the leading order of perturbative QCD and the nonrelativistic quark-diquark model of baryons we have obtained fragmentation function for c-quark to split into Omega_{ccc} baryon. It is shown that at LHC one can expect 3.5 10^3 events with Omega_{ccc} at p_t>5 GeV/c and -1<y<1 per year.Comment: LaTex, 5 pages and 2 figures. Talk presented at XIV Workshop on High Energy Physics and Quantum Field Theory, Moscow, May 27 - June 4, 199