arXiv subjects

Krzysztof Kurek

Publications and source records attributed to Krzysztof Kurek.

6 recordsLinked to original sources

arXiv2006

Delta G from Compass

Measurements of the gluon polarization $\frac{ΔG}{G}$ via the open charm channel and based on the helicity asymmetry of large transverse-momentum hadrons in the final state are presented. The data have been collected in the years 2002-2004 by the COMPASS experiment at CERN using a 160 GeV/c polarized muon beam scattered off a polarized $^6$LiD target. The new result for $\frac{ΔG}{G}$ from the charm channel is $-0.57 \pm 0.41 (stat.)$ at $x_G \simeq 0.15$ and scale $μ^2 \simeq 13 $ (GeV/c)$^2$. The gluon polarization from high-$p_T$ hadron pairs is $\frac{ΔG}{G} = 0.016\pm 0.058 (stat.)\pm 0.055 (syst.)$ at $x_G \simeq 0.085^{+0.07}_{-0.035}$ ($Q^2 < 1$ (GeV/c)$^2$ and $μ^2 \simeq 3$ (GeV/c)$^2$)

hep-ex↗

arXiv2005

Delta G from high pT events at SMC and high pT analysis at COMPASS

Measurements of the longitudinal spin cross section asymmetry for deep inelastic muon-nucleon interactions with two high transverse momentum hadrons ($p_T >$ 0.7 GeV) in the final state are presented for SMC data for polarized proton and deuteron and for data on polarized deuteron from COMPASS taken in 2002 and 2003. The muon asymmetries determined with a cut on $Q^2>$ 1 GeV$^2$ in SMC are: $A_p = 0.03 \pm 0.057\pm 0.01$ and $A_d = 0.070 \pm 0.076 \pm 0.010$, respectively. From these values a gluon polarization $ΔG /G = -0.20\pm 0.28\pm 0.10$ was obtained at an average fraction of nucleon momentum carried by gluons $η= 0.07$. The measured asymmetry (with cut on $Q^2>$ 1 GeV$^2$) in COMPASS is $(A_d/D) = -0.015 \pm 0.08 \pm 0.013$ where D is depolarization factor and the gluon polarization $ΔG /G = 0.06\pm 0.31\pm

hep-ex↗

arXiv2004

Superconvergence Relations and Parity Violating analogue of GDH sum rule

Sum rules of superconvergence type for parity violating amplitudes (p.v. analogue of Gerasimov-Drell-Hearn sum rule) are considered. Elementary processes initiated by polarized photons in the lowest order of electroweak theory are calculated as examples illustrating the validity of the p.v.sum rules. The parity violating polarized photon-induced processes for proton target are considered in the frame of effective low energy theories and phenomenological models based on p.v. nucleon-meson effective interactions. Assuming the saturation of p.v. sum rule the possibility to limit the range of the parameters, poorly known from existing experimental data and used in these models is discussed. The asymmetries for p.v. $π^0$ and $π^+$ production, measurable in future high intensity polarized photon beams experiments, are given.

hep-ph↗

arXiv1997

A Monte Carlo for POLarized (semi-inclusive) Deep Inelastic Scattering

POLDIS is a Monte Carlo program for polarized (semi-inclusive) deep inelastic scattering (DIS). Unpolarized DIS events are generated with the existing lepto-production event generators LEPTO for DIS and AROMA for Heavy Flavor production. The relevant spin asymmetries are computed at partonic level to first order in alpha_s for each generated event, and are then convoluted with the corresponding ratio between the polarized and unpolarized parton distribution functions (i.e. parton polarization). This procedure provides a polarization weight for each event. The average of these polarization weights gives the polarized cross section spin-asymmetry for the generated sample. The code consists of a set of subroutines to be linked with LEPTO and/or AROMA.

hep-ph↗

arXiv1996

QED Radiative Corrections in Exclusive $ρ^0$ Leptoproduction

The semi-analytical approach to the model independent leptonic QED corrections to exclusive $ρ^0$ meson leptoproduction (i.e. electron and muon scattering experiments) is presented. The corrections to $ρ^0$ production at large $Q^2$ as well as to $ρ^0$ photoproduction are studied in details. The numerical results are calculated for two different experimental analyses: NMC (muoproduction at large $Q^2$) and ZEUS at HERA (photoproduction). It is shown that the corrections are 2-5 \% for NMC and below 2 \% for the ZEUS measurement. The application of the presented approach to other vector mesons production is straightforward.

hep-ph↗

arXiv1994

Contribution of the elastic radiative tail to the deep inelastic muon scattering on heavy targets

Improvement of the radiative correction scheme for the deep inelastic scattering on the heavy targets is discussed. Arguments that the contribution of the radiative tail from the elastic peak should be calculated without use of the Born approximation in the case of the heavy target scattering are presented. The semianalytical approach based on the classical solution of the old bremsstrahlung problem is shortly described. The numerical results for the new correction factor are presented for the scattering on tin and lead.

hep-ph↗