G. I. Lykasov

Forward heavy-flavour production in pp collisions at LHC and intrinsic quark components in protons

The LHC data on the forward heavy-flavour hadron production can be a new unique source for estimation of intrinsic charm and bottom contributions to the proton. For example, we analyze the forward heavy-baryon production, namely Λb-baryon, within the soft QCD quark gluon string model and present the predictions for observables which could be measured at the LHC. We also present some predictions for the D-meson production in pp collisions made within the perturbative QCD including the intrinsic charm in the proton that can be verified at the LHC.

Transition between soft physics at LHC and low-x physics at HERA

We find out the connection between the unintegrated gluon distribution at low intrinsic transverse momenta and the inclusive spectrum of the hadrons produced in pp collision at LHC energies in the mid-rapidity region and low hadron transverse momenta. The parameters of this distribution are found from the best description of the LHC data. Its application to the analysis of ep deep inelastic scattering allows us to obtain the results which describe reasonably well the H1 and ZEUS data on the structure functions at low x. A connection between the soft processes at LHC and small x physics at HERA has been found.

Forward production of beauty baryons in pp collisions at LHC

The production of charmed and beauty baryons in proton-proton collisions at high energies is analyzed within the modified quark-gluon string model. We present some predictions for the experiments on the forward beauty baryon production in pp collisions at LHC energies. This analysis allows us to find useful information on the Regge trajectories of the heavy (b) mesons and the fragmentation functions of quarks to the bottom baryons.The production of charmed and beauty baryons in proton-proton collisions at high energies is analyzed within the modified quark-gluon string model. We present some predictions for the experiments on the forward beauty baryon production in pp collisions at LHC energies. This analysis allows us to find useful information on the Regge trajectories of the heavy (bb̄) mesons and the sea beauty quark distributions in the proton.

Backward hadron production in neutrino-nucleus interactions

Abstract: The production of backward pions in lepton-nucleus collisions is analyzed. We show that a large yield of high momentum backward pions can be explained by the Regge asymptotic of the distribution of nucleons carrying a large momentum fraction in the nuclear target. The calculated spectra of pions emitted in the ν+ Ne →μ+π−+ X and ν+2H →μ+π−+ X reactions are in satisfactory agreement with the available experimental data.

LHC soft physics and transverse momentum dependent gluon density at low x

We study the unintegrated, or transverse momentum dependent (TMD) gluon distribution obtained from the best description of the LHC data on the inclusive spectra of hadrons produced in the mid-rapidity region and at low transverse momenta at the starting scale Q 2 = 1 GeV 2 . To extend this gluon density to higher Q 2 we apply the Catani-Ciafoloni-Fiorani-Marchesini (CCFM) evolution equation. The influence of the initial (starting) non-perturbative gluon distribution is studied. The application of the obtained gluon density to the analysis of the deep inelastic ep scattering allows us to get the results which describe reasonably well the H1 and ZEUS data on the longitudinal proton structure function FL(x,Q 2 ). So, the connection between the soft processes at the LHC and small x physics at HERA has been confirmed and extended to a wide kinematical region.

ANGLE DEPENDENCE OF POLARIZATION OBSERVABLES BY FRAGMENTATION OF DEUTERONS TO PIONS

The fragmentation of deuterons into pions with nonzero angle emitted in the kinematical region forbidden for free nucleon-nucleon collisions is analyzed. The inclusive relativistic invariant spectrum of pions and the tensor analyzing power AYY are investigated within the framework of an impulse approximation using different kinds of the deuteron wave function. The influence of P-wave contribution to the deuteron wave function is studied, too. Our results are compared with the experimental data and other calculations performed within both the non-relativistic and relativistic approaches. It was found that theoretical calculations based on IA do not provide a consistent understanding of the new data in a whole cumulative region that can be caused by a influence of non-nucleon degrees of freedom.

Significance of nonperturbative input to the transverse momentum dependent gluon density for hard processes at the LHC

We study the role of the non-perturbative input to the transverse momentum dependent (TMD) gluon density in hard processes at the LHC. We derive the input TMD gluon distribution at low scale mu0^2 ~ 1 GeV^2 from the fit of the inclusive hadron spectra measured at low transverse momenta in pp collisions at the LHC and demonstrate that the best description of these spectra for larger hadron transverse momenta can be achieved by matching the derived TMD gluon distribution with the exact solution of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation obtained at low x and small gluon transverse momenta outside the saturation region. Then, we extend the input TMD gluon density to higher mu^2 numerically using the Catani-Ciafoloni-Fiorani-Marchesini (CCFM) gluon evolution equation. A special attention is put to the phenomenological applications of obtained TMD gluon density to some LHC processes, which are sensitive to the gluon content of a proton.

Unintegrated Gluon Distribution and Soft pp Collisions at LHC

We found the parameterization of the unintegrated gluon distribution from the best description of the LHC data on the inclusive spectra of hadrons produced in pp collisions at the mid-rapidity region and small transverse momenta. It is different from the one obtained within perturbative QCD only at low intrinsic transverse momenta kt. The application of this distribution to analysis of the e − p DIS allows us to get the results which do not contradict the H1 and ZEUS data on the structure functions at low x. So, the connection between the soft processes at LHC and low-x physics at HERA is found.

Transverse-momentum spectra of hadrons produced in central heavy-ion collisions

In-medium effects of transverse-mass distributions of quarks and gluons are considered assuming a possible local equilibrium for colorless quark objects like mesons and baryons created in central AA collisions. It is shown that the average square of the transverse momentum for these partons grows and then saturates when the initial energy increases. Within the quark-gluon string model, it leads to an energy dependence of hadron transverse-mass spectra which is similar to that observed in heavy-ion collisions. A comparison with other scenarios is given.In-medium effects of transverse-mass distributions of quarks and gluons are considered assuming a possible local equilibrium for colorless quark objects like mesons and baryons created in central A+A collisions. It is shown that the average square of the transverse momentum for these partons grows and then saturates when the initial energy increases. Within the quark-gluon string model it leads to the energy dependence of hadron transverse mass spectra which is similar to that observed in heavy ion collisions. Comparison with other scenarios is given.

Saturation of gluon density and soft

We find the relation of the unintegrated gluon distribution at low intrinsic transverse momenta to the inclusive spectrum of the hadrons produced in pp collision at LHC energies in the mid-rapidity region and low hadron transverse momenta. It allows us to study the saturation of the gluon density at low Q2 more carefully and find the saturation scale that does not contradict to both the LHC and HERA data.