6,373 research outputs found
NLO QCD method of the polarized SIDIS data analysis
Method of polarized semi-inclusive deep inelastic scattering (SIDIS) data
analysis in the next to leading order (NLO) QCD is developed. Within the method
one first directly extracts in NLO few first truncated (available to
measurement) Mellin moments of the quark helicity distributions. Second, using
these moments as an input to the proposed modification of the Jacobi polynomial
expansion method (MJEM), one eventually reconstructs the local quark helicity
distributions themselves. All numerical tests demonstrate that MJEM allows us
to reproduce with the high precision the input local distributions even inside
the narrow Bjorken region accessible for experiment. It is of importance
that only four first input moments are sufficient to achieve a good quality of
reconstruction. The application of the method to the simulated SIDIS data on
the pion production is considered. The obtained results encourage one that the
proposed NLO method can be successfully applied to the SIDIS data analysis. The
analysis of HERMES data on pion production is performed. To this end the pion
difference asymmetries are constructed from the measured by HERMES standard
semi-inclusive spin asymmetries. The LO results of the valence distribution
reconstruction are in a good accordance with the respective leading order SMC
and HERMES results, while the NLO results are in agreement with the existing
NLO parametrizations on these quantities
Conductance characteristics of current-carrying d-wave weak links
The local quasiparticle density of states in the current-carrying d-wave
superconducting structures was studied theoretically. The density of states can
be accessed through the conductance of the scanning tunnelling microscope. Two
particular situations were considered: the current state of the homogeneous
film and the weak link between two current-carrying d-wave superconductors.Comment: 4 pages, 3 figures; to appear in Low. Temp. Phy
Charge ordering and interlayer phase coherence in quantum Hall superlattices
The possibility of the existence of states with a spontaneous interlayer
phase coherence in multilayer electron systems in a high perpendicular to the
layers magnetic field is investigated. It is shown that phase coherence can be
established in such systems only within individual pairs of adjacent layers,
while such coherence does not exist between layers of different pairs. The
conditions for stability of the state with interlayer phase coherence against
transition to a charge-ordered state are determined. It is shown that in the
system with the number of layers N\leq 10 these conditions are satisfied at any
value of the interlayer distance d. For N>10 there are two intervals of
stability: at sufficiently large and at sufficiently small d. For N\to \infty
the stability interval in the region of small d vanishesComment: 10 page
Direct extraction of transversity and its accompanying T-odd distribution from the unpolarized and single-polarized Drell-Yan processes
The Drell-Yan (DY) processes with unpolarized colliding hadrons and with the
single transversally polarized hadron are considered. The possibility of direct
(without any model assumptions) extraction of both transversity and its
accompanying T-odd parton distribution functions (PDF) is discussed. For DY
processes measurements planned at GSI the preliminary estimations demonstrate
that it is quite real to extract both transversity and its accompanying T-odd
PDF in the PAX conditions
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