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A. Tkabladze

Publications and source records attributed to A. Tkabladze.

11 recordsLinked to original sources

Separated Structure Functions for the Exclusive Electroproduction of $K^+Λ$ and $K^+Σ^0$ Final States

We report measurements of the exclusive electroproduction of $K^+Λ$ and $K^+Σ^0$ final states from a proton target using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The separated structure functions $σ_T$, $σ_L$, $σ_{TT}$, and $σ_{LT}$ were extracted from the $Φ$- and $ε$-dependent differential cross sections taken with electron beam energies of 2.567, 4.056, and 4.247 GeV. This analysis represents the first $σ_L/σ_T$ separation with the CLAS detector, and the first measurement of the kaon electroproduction structure functions away from parallel kinematics. The data span a broad range of momentum transfers from $0.5\leq Q^2\leq 2.8$ GeV$^2$ and invariant energy from $1.6\leq W\leq 2.4$ GeV, while spanning nearly the full center-of-mass angular range of the kaon. The separated structure functions reveal clear differences between the production dynamics for the $Λ$ and $Σ^0$ hyperons. These results provide an unprecedented data sample with which to constrain current and future models for the associated production of strangeness, which will allow for a better understanding of the underlying resonant and non-resonant contributions to hyperon production.

hep-ex

Target Mass Corrections to the Spin-dependent Structure Functions

The target mass corrections to the twist-2 contributions of the spin-dependent structure functions are calculated using operator product expansion in lowest order in QCD. The influence of such corrections to the different relations between the structure functions is considered.

hep-ph

On the Gauge Invariance of the Z-Boson Mass

The different schemes for the definition of the Z boson mass are analyzed. It is shown that the scheme, defining the mass as pole of the real part of the Z boson propagator and the width as the imaginary part of the propagator at the same point results in the gauge dependent results for these parameters in a two-loop approximation. On the other hand, the scheme, where the mass and width are related to the position of the pole of the propagator in the complex plane leads to the gauge independent result. It is argued that the gauge dependence of mass and width does not contradicts to the gauge invariance of the amplitude.

hep-ph

Nucleon Mass Corrections to Spin Dependent Structure Functions and Relations Between their Twist-3 Contributions

The nucleon mass corrections are calculated to all polarized structure functions for neutral and charged current deep inelastic scattering in lowest order in the coupling constant. The impact of the target mass corrections on the general relations between the twist--2 and twist--3 parts of the structure functions is studied and three new relations between the twist--3 contributions are derived. The size of nucleon mass corrections for the $g_1$ and $g_2$ structure functions are estimated.

hep-ph

Target Mass Corrections for Polarized Structure Functions and New Sum Rules

The target mass corrections are calculated for all structure functions of neutral and charged current deep inelastic scattering in lowest order in the coupling constant. Representations of the correction to the twist--2 and twist--3 contributions are derived both in Mellin-$n$ and $x$-space. The impact of the target mass corrections on the general relations between the twist--2 and twist--3 parts of the structure functions is studied and three new relations between the twist--3 contributions are derived.

hep-ph

$Υ$ Polarization at HERA-$B$

The production of $Υ$ mesons in fixed target $pN$ collisions is considered. It is shown that Non-Relativistic QCD predicts $Υ$ states to be produced with sizeable transverse polarization. The possibility of a measurement of the $Υ$ polarization at the HERA-$B$ experiment is discussed.

hep-ph

Double Spin Asymmetries in Charmonium Hadroproduction at HERA-$\vec N$

We discuss the double spin asymmetries in charmonium hadroproduction with nonzero transverse momenta at fixed target energies, $\sqrt{s}\simeq40$ GeV, within the framework of the factorization approach. It is shown that the color octet contribution is dominant in the asymmetries. The size of the asymmetries and the projected statistical errors in a future option of HERA with longitudinally polarized protons scattering off a polarized target (HERA-$\vec N$) should allow to distinguish between different parametrizations for the polarized gluon distribution in the proton.

hep-ph

On the Physics Potential of Polarized Nucleon-Nucleon Collisions at HERA

The physics of polarized nucleon--nucleon collisions originating from an internal polarized target in the HERA proton beam is investigated. Based on 240 pb^-1 integrated luminosity at 40 GeV c.m. energy, statistical sensitivities are given over a wide (x_F, p_T) range for a variety of inclusive and exclusive final states. By measuring single spin asymmetries unique information can be obtained on higher twist contributions and their p_T-dependence. From double spin asymmetries in both photon and J/psi production it appears possible to measure the polarized gluon distribution in the range 0.1<x_gluon<0.4 with a good statistical accuracy.

hep-ph

Photon-Photon Scattering at the Photon Linear Collider

Photon-photon scattering at the Photon Linear Collider is considered. Explicit formulas for helicity amplitudes due to $W$ boson loops are presented. It is shown that photon-photon scattering should be easily observable at PLC and separation of the $W$ loop contribution (which dominates at high energies) will be possible at $e^+e^-$ c.m. energy of 500~GeV or higher.

hep-ph

$γZ$ Pair Production at the Photon Linear Collider

$γγ\toγZ$ scattering at the Photon Linear Collider is considered. Explicit formulas for helicity amplitudes due to $W$ boson loops are presented. It is shown that the $Zγ$ pair production will be easily observable at PLC and separation of the $W$ loop contribution will be possible at $e^+e^-$ c.m. energy of 300~GeV or higher.

hep-ph