23,686 research outputs found
On the beam spin asymmetries of electroproduction of charged hadrons off the nucleon targets
We study the beam single-spin asymmetries for charged
hadrons produced in semi-inclusive deep inelastic scattering process, by
considering the term and the term simultaneously.
Besides the asymmetries for charged pions, for the first time we present the
analysis on the asymmetries in the production of charged kaons, protons and
antiprotons by longitudinally polarized leptons scattered off unpolarized
proton and deuteron targets. In our calculation we use two sets of transverse
momentum dependent distributions and
calculated from two different spectator models, and compare the numerical
results with the preliminary data recently obtained by the HERMES
Collaboration. We also predict the beam spin asymmetries for ,
, electroproduction in semi-inclusive deep-inelastic
scattering of 12 GeV polarized electrons from unpolarized proton and deuteron
targets.Comment: 9 pages, 6 figures, version accepted by EPJ
Beam Spin Asymmetries of Charged and Neutral Pion Productions in Semi-inclusive DIS
We present a study on the beam single spin asymmetries
of , and production in semi-inclusive deep inelastic
scattering process, by considering Collins effect and the term
simultaneously. We calculate the twist-3 distributions and
for the valence quarks inside the proton in a spectator
model. We consider two different options for the form of diquark propagator, as
well as two different choices for the model parameters in the calculation.
Using the model results, we estimate the beam spin asymmetries
for the charged and neutral pions and compare the results
with the measurement from the HERMES Collaboration. We also make predictions on
the asymmetries at CLAS with a beam using the same model
results. It is found that different choices for the diquark propagator will not
only lead to different expressions for the distribution functions, but also
result in different sizes of the asymmetries. Our study also shows that,
although the spectator model calculation can describe the asymmetries for
certain pion production in some kinematic regions, it seems difficult to
explain the asymmetries of pion production for all three pions in a consistent
way from the current versions.Comment: 9 pages, 8 figure
B to light meson transition form factors calculated in perturbative QCD approach
We calculate the , (P: light pseudoscalar meson, V light
vector meson) form factors in the large-recoil limit in perturbative QCD
approach, including both the vector (axial vector) and tensor operators. In
general there are two leading components and for
meson wave functions. We consider both contributions of them. Sudakov effects
( and threshold resummation) are included to regulate the soft
end-point singularity. By choosing the hard scale as the maximum virtualities
of internal particles in the hard -quark decay amplitudes, Sudakov factors
can effectively suppress the long-distance soft contribution. Hard contribution
can be dominant in these approaches.Comment: 21 pages, with 2 figure
Transverse single-spin asymmetries of pion production in semi-inclusive DIS at subleading twist
We study the single-spin asymmetries with the and angular dependences for charged and neutral pions produced in
semi-inclusive deep inelastic scattering on the transversely polarized proton
target. The theoretical interpretations of the two asymmetries are presented in
terms of the convolution of the twist-3 quark transverse momentum dependent
distributions and twist-2 fragmentation functions. Specifically, we investigate
the role of the distributions , and in the
asymmetry, as well as the role of the distributions , and
in the asymmetry. We calculate these
distributions in a spectator-diquark model and predict the corresponding
asymmetries for the first time, considering the kinematics at HERMES, JLab and
COMPASS. The numerical estimates show that the asymmetries are sizable, and the
dominant contribution to the asymmetry comes from the T-odd
distribution , while gives the main contribution to the
asymmetry. The future measurements on these asymmetries
can shed light on the information of twist-3 transverse momentum dependent
distributions.Comment: 11 pages, 12 figures, version published in PR
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