Processes of heavy quark pair (lepton pair) and two gluon (two photon) production in the high energy quark (electron) proton peripheral collisions

We considered the three jet production processes in the region of the incident lepton, photon, quark or gluon fragmentation. The fourth jet is created by the recoil proton. The kinematics of jet production is discussed in jets production in the fragmentation region. The non-trivial relation between the momenta of the recoil proton and the polar angle of its emission was derived. Based on this formalism the differential cross sections of QCD processes $gp \to (ggg) p; \,\,\,qp \to (q \bar{Q} Q) p; \,\,\, gp \to (g Q \bar{Q})p$ were obtained, including the distribution on transverse momentum component of jets fragments. It was shown that the role of the contribution of "non-Abelian" nature may become dominant in a particular kinematics of the final particles. The kinematics, in which the initial particle changes the direction of movement to the opposite one, was considered in the case of heavy quark-antiquark pair production. Different distributions, including spectral, azimuthal and polar angle distribution on the fragments of jets can be arranged using our results. We present besides the behavior of the ratio of non-Abelian contribution to the cross section to the total contribution. We show that it dominates for large values of the transverse momenta of jets component (gluons or quarks). Some historical introduction to the cross-sections of peripheral processes, including 2$\gamma$ creation mechanism production, including the result Brodsky-Kinoshita-Terazawa, is given.Comment: 25 pages, 4 figures, 5 table

Quadratic electroweak corrections for polarized Moller scattering

The paper discusses the two-loop (NNLO) electroweak radiative corrections to the parity violating electron-electron scattering asymmetry induced by squaring one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV MOLLER experiment planned at Jefferson Laboratory and experiments at high-energy future electron colliders. The imaginary parts of the amplitudes are taken into consideration consistently in both the infrared-finite and divergent terms. The size of the obtained partial correction is significant, which indicates a need for a complete study of the two-loop electroweak radiative corrections in order to meet the precision goals of future experiments

Single-Spin Asymmetries for Small-Angle Pion Production in High-Energy Hadron Collisions

Within the framework of a simple model, we study single-spin asymmetries for pion production in hadron-hadron collisions at high-energies with one hadron polarised. The asymmetries are generated via a mechanism of final (initial) state interactions. For peripheral kinematics, when the pion belongs to the fragmentation region of the polarised proton, we find non-zero asymmetries in the high-energy limit. Numerical results and comparision with existing experimental data are presented. We also discuss the relationship with odderon exchange phenomenology.Comment: LaTeX2e, 12 pages, 4 figure files (2 TeX and 2 eps), uses axodraw, and cite packages; submitted to Eur. Phys. J

Near threshold radiative 3π\pi production in e+e−e^+e^- annihilation

We consider the $\pi^+\pi^-\pi_0\gamma$ final state in electron-positron annihilation at cms energies not far from the threshold. Both initial and final state radiations of the hard photon is considered but without interference between them. The amplitude for the final state radiation is obtained by using the effective Wess-Zumino-Witten Lagrangian for pion-photon interactions valid for low energies. In real experiments energies are never such small that $\rho$ and $\omega$ mesons would have negligible effect. So a phenomenological Breit-Wigner factor is introduced in the final state radiation amplitude to account for the vector mesons influence. Using radiative 3$\pi$ production amplitudes, a Monte Carlo event generator was developed which could be useful in experimental studies.Comment: 15 pages, Latex, 6 figures. Misprints corrected. Version to be published in JHE

QED Corrections to Deep Inelastic Scattering with Tagged Photons at HERA

We calculate the QED corrections to deep inelastic scattering with tagged photons at HERA in the leading logarithmic approximation. Due to the special experimental setup, two large scales appear in the calculation that lead to two large logarithms of comparable size. The relation of our formalism to the conventional structure function formalism is outlined. We present some numerical results and compare with previous calculations.Comment: 7 pages, REVTeX, 2 figures; published versio

Radiatively corrected lepton energy distributions in top quark decays t→bW+→b(ℓ+νℓ)t \to b W^+ \to b(\ell^+ \nu_\ell) and t→bH+→b(τ+ντ)t \to b H^+ \to b(\tau^+\nu_\tau) and single charged prong energy distributions from subsequent τ+\tau^+ decays

We calculate the QED and QCD radiative corrections to the charged lepton energy distributions in the dominant semileptonic decays of the top quark $t \to b W^+ \to b(\ell^+ \nu_\ell)$ $(\ell=e, \mu, \tau)$ in the standard model(SM), and for the decay $t \to b H^+ \to b(\tau^+ \nu_\tau)$ in an extension of the SM having a charged Higgs boson $H^\pm$ with $m_{H^\pm} < m_t -m_b$. The QCD corrections are calculated in the leading and next-to-leading logarithmic approximations, but the QED corrections are considered in the leading logarithmic approximation only. These corrections are numerically important for precisely testing the universality of the charged current weak interactions in $t$-quark decays. As the $\tau^+$ leptons arising from the decays $W^+ \to \tau^+ \nu_\tau$ and $H^+\to \tau^+ \nu_\tau$ are predominantly left- and right-polarised, respectively, influencing the energy distributions of the decay products in the subsequent decays of the $\tau^+$, we work out the effect of the radiative corrections on such distributions in the dominant (one-charged prong) decay channels $\tau^+ \to \pi^+ \bar{\nu}_\tau, \rho^+ \bar{\nu}_\tau, a_1^+ \bar{\nu}_\tau$ and $\ell^+ \nu_\ell \bar{\nu}_\tau$. The inclusive $\pi^+$ energy spectra in the decay chains $t \to b(W^+,H^+) \to b (\tau^+ \nu_\tau) \to b (\pi^+ \bar{\nu}_\tau \nu_\tau +X)$ are calculated, which can help in searching for the induced $H^\pm$ effects at the Tevatron and the LHC.Comment: 39 pages, 18 figure