67 research outputs found
Neutron unpolarized structure function F_2^n(x) from deep inelastic scattering off ^{3}He and ^{3}H
The possibility to safely extract the neutron deep inelastic structure
function in the range from joint measurements of
deep inelastic structure functions of and is demonstrated.
While the nuclear structure effects are relevant, the model dependence in this
extraction linked to the interaction is shown to be weak.Comment: 5 pages. Proc. XVIIth Conf. on "Few-Body Problems in Physics", Evora(
Portugal) Sept. 11, 2000. To appear in Nucl. Phys.
Transversity studies with a polarized 3He target
A realistic study of the SiDIS process 3He(e , e
Ď)X in the Bjorken
limit is briefly reviewed, showing that the nuclear effects, present in the extraction
of the neutron information, are largely under theoretical control, within an ImpulseApproximation approach. In view of the forthcoming experimental data, we shortly
present a novel Poincar´e covariant description of the nuclear target, implementing a
Light-Front analysis at finite Q2, within the Bakamijan-Thomas construction of the
Poincar´e generators. Furthermore, as a by-product of the introduction of a LightFront spin-dependent spectral function for a J = 1/2 system, we straightforwardly
extend our analysis to the quark-quark correlator, obtaining three new exact relations between the six leading-twist Transverse-MomentumâDependent distributions
EFFECTS OF COGNITIVE TRAINING AND TRANSCRANIAL DIRECT CURRENT STIMULATION ON WORKING MEMORY OF PATIENTS WITH TREATMENT-RESISTANT SCHIZOPHRENIA: A DOUBLE BLIND, RANDOMIZED, SHAM-CONTROLLED STUDY PROTOCOL
EFFECTS OF COGNITIVE TRAINING AND TRANSCRANIAL DIRECT CURRENT STIMULATION ON WORKING MEMORY OF PATIENTS WITH TREATMENT-RESISTANT SCHIZOPHRENIA: A DOUBLE BLIND, RANDOMIZED, SHAM-CONTROLLED STUDY PROTOCOL
Single-spin Azimuthal Asymmetries in the ``Reduced Twist-3 Approximation''
We consider the single-spin azimuthal asymmetries recently measured at the
HERMES experiment for charged pions produced in semi-inclusive deep inelastic
scattering of leptons off longitudinally polarized protons. Guided by the
experimental results and assuming a vanishing twist-2 transverse quark spin
distribution in the longitudinally polarized nucleon, denoted as ``reduced
twist-3 approximation'', a self-consistent description of the observed
single-spin asymmetries is obtained. In addition, predictions are given for the
z dependence of the single target-spin asymmetry.Comment: 8 pages, 2 figures, typos corrected, very small changes to text,
reference adde
The pion transition form factor and the pion distribution amplitude
Recent BaBaR data on the pion transition form factor, whose Q^2 dependence is
much steeper then predicted by asymptotic Quantum Chromodynamics (QCD), have
caused a renewed interest in its theoretical description. We present here a
formalism based on a model independent low energy description and a high energy
description based on QCD, which match at a scale Q_0. The high energy
description incorporates a flat pion distribution amplitude, phi(x)=1, at the
matching scale Q_0 and QCD evolution from Q_0 to Q>Q_0. The flat pion
distribution is connected, through soft pion theorems and chiral symmetry, to
the pion valance parton distribution at the same low scale Q_0. The procedure
leads to a good description of the data, and incorporating additional twist
three effects, to an excellent description of the data.Comment: 11 pages, 5 postscript figures, uses epsfig.sty and 1 appendi
Perturbative contribution to the sin(phi) asymmetry in inclusive pi^{+} electroproduction
We consider the sin(phi) single target-spin asymmetry in deep-inelastic
pi^{+} inclusive electroproduction off a longitudinally polarized target. We
show that at larger transverse momentum of the outgoing hadron the evaluated
asymmetry decreases if one takes into account the first order alpha_S
perturbative contribution to the cross section, integrated over the azimuthal
angle. This leads to good agreement with recent HERMES data.Comment: 4 pages with one figure, LaTeX, typos corrected. Contribution to the
Proceedings of the QCD'00 Euroconference, Montpellier, 6-13th July 2000, to
appear in the Nucl. Phys. B (Proc. Suppl.
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