arXiv subjects
Publications and source records attributed to Leszek Motyka.
Diffractive heavy vector meson photoproduction accompanied by proton dissociation is studied for arbitrary momentum transfer. The process is described by the non-forward BFKL equation, for which a complete analytical solution is found, giving the scattering amplitude. The impact of non-leading corrections to the BFKL equation is also analysed. Results are compared to the HERA data on J/psi production.
We consider inelastic collisions between atoms of different kinds as a potential source of photons in the sonoluminescence phenomena. We estimate the total energy emitted in one flash and the shape of the spectrum and find a rough agreement between the results of our calculation and the experimental data. We conclude that the atomic collisions might be a candidate for the light-emitting mechanism for sonoluminescence and discuss the implications.
The reaction γγ---> J/Psi J/Psi is discussed assuming dominance of the QCD BFKL pomeron exchange. We give prediction for the cross-section of this process for LEP2 and TESLA energies. We solve the BFKL equation in the non-forward configuration taking into account dominant non-leading effects which come from the requirement that the virtuality of the exchanged gluons along the gluon ladder is controlled by their transverse momentum squared. We compare our results with those corresponding to the simple two gluon exchange mechanism and with the BFKL pomeron exchange in the leading logarithmic approximation. The BFKL effects are found to generate a steeper t-dependence than the two gluon exchange. The cross-section is found to increase with increasing CM energy W as (W^2)^{2λ}. The parameter λis slowly varying with W and takes the values lambda \sim 0.23 - 0.28. The magnitude of the total cross-section for the process γγ--> J/Psi J/Psi is found to increase from 4 to 26 pb within the energy range accessible at LEP2. The magnitude of the total cross-section for the process e^+e^- ---> e^+e^- J/Psi J/Psi with antitagged e^+ and e^- is estimated to be around 0.1 pb at LEP2.
A nonrelativistic Hamiltonian with plausible spin dependent corrections is proposed for the quarkonia below their respective strong decay thresholds. With only six free parameters this model reproduces the nine known masses of the bottomonia within about 1 MeV, the six known masses of the charmonia within a few MeV and the five known leptonic decay widths of the ${}^3S_1$ states within about {20 %}. The model is then used to predict the masses of the remaining 43 quarkonia (some of them for the first time) and of the leptonic decay widths of the two ${}^1S_0(\bar{b}c)$ states. Comparison with some other models is made.
Analytic formulae are given for order alpha_s perturbative QCD corrections to the double differential distribution of the tau lepton energy and the invariant mass of the tau + antineutrino system in semileptonic decays of the bottom quark. The corresponding distribution for B meson decays are obtained by combining these results and the nonperturbative QCD corrections calculated by Falk et al. The moments of the energy distribution of the tau lepton are calculated.
Perturbative corrections of the order of $α_s$ to inclusive double differential lepton distribution from $b$ quark decay are considered. A perturbative correction to the charged lepton energy spectrum has been calculated for an arbitrary charged lepton mass. The perturbative contribution suppresses the partial rate but almost does not change the shape of energy distribution. Applications of our result to semileptonic B meson decays are briefly discussed.
A systematic study of a wide class of nonrelativistic models of $b\overline{b}$ quarkonia is described. It is found that the potential $V(r) = 0.706380(\sqrt{r} - \frac{0.460442}{r}) + 8.81715$ (all in GeV) with the $b$-quark mass $m_b = 4.80303$ GeV gives a satisfactory description of the experimental data below the threshold for strong decays ($ χ^2/DF = 6.5/7$). Limitations and implications of this observation are discussed.