407 research outputs found
GeMSE: A new Low-Background Facility for Meteorite and Material Screening
We are currently setting up a facility for low-background gamma-ray
spectrometry based on a HPGe detector. It is dedicated to material screening
for the XENON and DARWIN dark matter projects as well as to the
characterization of meteorites. The detector will be installed in a medium
depth (620 m.w.e.) underground laboratory in Switzerland with several
layers of shielding and an active muon-veto. The GeMSE facility will be
operational by fall 2015 with an expected background rate of 250
counts/day (100-2700 keV).Comment: The following article appeared in AIP Conf. Proc. 1672, 120004 (2015)
and may be found at
http://scitation.aip.org/content/aip/proceeding/aipcp/10.1063/1.4928010. The
muon spectrum in Figure 4 (left) was corrected due to a bug in the code.
After correction the muon flux is reduced by a factor of about
Single spin asymmetry for in perturbative QCD
Within the QCD-improved parton model and assuming the factorization theorem
to hold in the helicity basis and for higher twist contributions, we show how
non zero single spin asymmetries in hadron-hadron high energy and moderately
large inclusive processes can be obtained, even in massless perturbative
QCD, provided the quark intrinsic motion is taken into account. A simple model
is constructed which reproduces the main features of the data on the single
spin asymmetry observed in inclusive pion production in collisions.Comment: 11 pages + 1 figure, plain LaTeX, figure appended as uuencoded,
compressed postscript file. Revised version, to be published in Phys. Lett.
B; extensive changes in Sections 1 and 2, new References added, results and
conclusions essentially unchange
On the new COMPASS measurement of the deuteron spin-dependent structure function
Very recently, a new measurement of the deuteron spin-dependent structure
function was reported by the COMPASS group. A main change from the
old SMC measurement is a considerable improvement of the statistical accuracy
in the low region . We point out that the new COMPASS
data for as well as their QCD fits for and are all remarkably close to our theoretical predictions
given several years ago based on the chiral quark soliton model.Comment: Errors in Fig.4 were corrected. Version accepted for publication in
Physics Letters
Single spin asymmetries in DIS
We consider possible mechanisms for single spin asymmetries in inclusive Deep
Inelastic Scattering (DIS) processes with unpolarized leptons and transversely
polarized nucleons. Tests for the effects of non-zero \bfk_\perp, for the
properties of spin dependent quark fragmentations and for quark helicity
conservation are suggested.Comment: 5 pages, LaTeX, no figures. Revised version, to be published in Phys.
Rev. D. Some equations and statements added to clarify text and notation
Accessing transversity via J/Psi production in polarized p-pbar interactions
We discuss the possibility of a direct access to transversity distributions
by measuring the double transverse spin asymmetry A_TT in p pbar --> J/Psi + X
--> l^- l^+ + X processes at future GSI-HESR experiments with polarized protons
and anti-protons. In the J/Psi resonance production region, with 30 < s < 45
GeV^2, both the cross-section and A_TT are expected to be sufficiently large to
allow a measurement of h_1^q(x,M^2); numerical estimates are given.Comment: 10 pages, 2 figures. Version accepted for publication in PLB;
comments and references adde
Transverse momentum dependence in gluon distribution and fragmentation functions
We investigate the twist two gluon distribution functions for spin 1/2
hadrons, emphasizing intrinsic transverse momentum of the gluons. These
functions are relevant in leading order in the inverse hard scale in scattering
processes such as inclusive leptoproduction or Drell-Yan scattering, or more
general in hard processes in which at least two hadrons are involved. They show
up in azimuthal asymmetries. For future estimates of such observables, we
discuss specific bounds on these functions.Comment: 14 pages, revtex, 7 Postscript figure
On asymmetry in inclusive pion production
On the basis of the mechanism proposed for one-spin asymmetries in inclusive
hadron production we specify an --dependence of asymmetries in inclusive
processes of pion production. The main role in generation of this asymmetry
belongs to the orbital angular momentum ofquark-antiquark cloud in internal
structure of constituent quarks. The --dependence of asymmetries in the
charged pion production at large reflects the corresponding dependence of
constituent quark polarization in the polarized proton.Comment: LaTeX, 8 pages, 3 figures. One figure added, as it appears in Phys.
Rev.
Quark Correlations and Single Spin Asymmetries
We analyze the Sivers asymmetry in light-cone gauge. The average transverse
momentum of the quark distribution is related to the correlation between the
quark distribution and the transverse component of the gauge field at . We then use finiteness conditions for the light-cone Hamiltonian to
relate the transverse gauge field at to the color density
integrated over . This result allows us to relate the average transverse
momentum of the active quark to color charge correlations in the transverse
plane.Comment: 8 pages, 1 figur
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