6,439 research outputs found
Master Formula for the Three-Gluon Contribution to Single Spin Asymmetry in Semi-Inclusive Deep Inelastic Scattering
We derive a "master formula" for the contribution of the three-gluon
correlation function in the nucleon to the twist-3 single-spin-dependent cross
section for semi-inclusive deep-inelastic scattering, ep^\uparrow\to eDX. This
is an extension of the similar formula known for the so-called soft-gluon-pole
contribution induced by the quark-gluon correlation function in a variety of
processes. Our master formula reduces the relevant interfering partonic
subprocess with the participation of the three gluons to the Born cross
sections for the \gamma^*g\to c\bar{c} scattering, which reveals the new
structure behind the twist-3 single spin asymmetry and simplifies the actual
calculation greatly. A possible extension to higher order corrections is also
discussed.Comment: 23 pages, 4 figures. Final version to appear in Phys. Rev. D.
Presentation changed slightl
Three-gluon contribution to the single spin asymmetry in Drell-Yan and direct-photon processes
We derive the single-spin-dependent cross section for the Drell-Yan
lepton-pair production and the direct-photon production in the -collision
induced by the twist-3 three-gluon correlation functions in the transversely
polarized nucleon in the leading order with respect to the QCD coupling
constant. Combined with the contribution from the twist-3 quark-gluon
correlation functions in the literature, this completes the twist-3 cross
section for these processes. We also present a model calculation of the
asymmetry for the direct photon production at the RHIC energy, demonstrating
the sensitivity of the asymmetry to the form of the three-gluon correlation
functions. In particular, we show that the asymmetry in the backward direction
of the polarized nucleon is determined by the small- behavior of the
correlation functions.Comment: 15 pages, 3 figure
Contribution of Twist-3 Multi-Gluon Correlation Functions to Single Spin Asymmetry in Semi-Inclusive Deep Inelastic Scattering
As a possible source of the single transverse spin asymmetry, we study the
contribution from purely gluonic correlation represented by the twist-3
``three-gluon correlation" functions in the transversely polarized nucleon. We
first define a complete set of the relevant three-gluon correlation functions,
and then derive its contribution to the twist-3 single-spin-dependent cross
section for the -meson production in semi-inclusive deep inelastic
scattering, which is relevant to determine the three-gluon correlations. Our
cross-section formula differs from the corresponding result in the literature,
and the origin of the discrepancy is clarified.Comment: 29 pages, 3 figures minor corrections; version to appear in Phys.
Rev.
On the contribution of twist-3 multi-gluon correlation functions to single transverse-spin asymmetry in SIDIS
We study the single spin asymmetry (SSA) induced by purely gluonic
correlation inside a nucleon, in particular, by the three-gluon correlation
functions in the transversely polarized nucleon, . This
contribution is embodied as a twist-3 mechanism in the collinear factorization
framework and controls the SSA to be observed in the -meson production with
large transverse-momentum in semi-inclusive DIS (SIDIS), . We define the relevant three-gluon correlation functions in
the nucleon, and determine their complete set at the twsit-3 level taking into
account symmetry constraints in QCD. We derive the single-spin-dependent cross
section for the -meson production in SIDIS, taking into account all the
relevant contributions at the twist-3 level. The result is obtained in a
manifestly gauge-invariant form as the factorization formula in terms of the
three-gluon correlation functions and reveals the five independent structures
with respect to the dependence on the azimuthal angle for the produced
meson. We also demonstrate the remarkable relation between the twist-3
single-spin-dependent cross section and twist-2 cross sections for the
-meson production, as a manifestation of universal structure behind the SSA
in a variety of hard processes.Comment: 8 pages, 2 figures. To appear in the proceedings of the 19th
International Spin Physics Symposium (SPIN2010), Juelich, Germany, Sept.27 -
Oct.2, 201
Time-Evolution of a Collective Meson Field by the Use of a Squeezed State
A time-evolution of quantum meson fields is investigated in a linear sigma
model by means of the time-dependent variational approach with a squeezed
state. The chiral condensate, which is a mean field of the quantum meson
fields, and quantum fluctuations around it are treated self-consistently in
this approach. The attention is payed to the description of the relaxation
process of the chiral condensate, where the energy stored in the mean field
configuration flows to the fluctuation modes. It is shown that the quantum
fluctuations play an important role to describe this relaxation process.Comment: 18 pages, 22 postscript figures, uses PTPTeX.st
Quantum Brachistochrone for Mixed States
We present a general formalism based on the variational principle for finding
the time-optimal quantum evolution of mixed states governed by a master
equation, when the Hamiltonian and the Lindblad operators are subject to
certain constraints. The problem reduces to solving first a fundamental
equation (the {\it quantum brachistochrone}) for the Hamiltonian, which can be
written down once the constraints are specified, and then solving the
constraints and the master equation for the Lindblad and the density operators.
As an application of our formalism, we study a simple one-qubit model where the
optimal Lindblad operators control decoherence and can be simulated by a
tunable coupling with an ancillary qubit. It is found that the evolution
through mixed states can be more efficient than the unitary evolution between
given pure states. We also discuss the mixed state evolution as a finite time
unitary evolution of the system plus an environment followed by a single
measurement. For the simplest choice of the constraints, the optimal duration
time for the evolution is an exponentially decreasing function of the
environment's degrees of freedom.Comment: 8 pages, 3 figure
A phenomenological study of single transverse-spin asymmetry for inclusive light-hadron productions at RHIC
We study the single transverse-spin asymmetry for inclusive light-hadron
productions in the proton-proton collision, \pphx (), for the
RHIC kinematics based on the twist-3 mechanism in the collinear factorization.
The analysis includes all the contributions from the soft-gluon pole and the
soft-fermion pole for the twist-3 quark-gluon correlation functions in the
transversely polarized proton. After discussing the flavor decomposition and
the -dependence of the asymmetry obtained in the previous analysis at the
center-of-mass energy and 200 GeV, we will give a prediction
for the asymmetry at GeV and also for the -meson
production. We found slightly smaller asymmetry at GeV for
and compared with those at the lower energies. The
asymmetry for the -meson turned out to be significantly larger than that
for .Comment: 12 pages, 8 figures, Final version published in Phys. Rev. D 83,
114024 (2011
Transverse single-spin asymmetries in proton-proton collisions at the AFTER@LHC experiment
We present results for transverse single-spin asymmetries in proton-proton
collisions at kinematics relevant for AFTER, a proposed fixed-target experiment
at the Large Hadron Collider. These include predictions for pion, jet, and
direct photon production from analytical formulas already available in the
literature. We also discuss specific measurements that will benefit from the
higher luminosity of AFTER, which could help resolve an almost 40-year puzzle
of what causes transverse single-spin asymmetries in proton-proton collisions.Comment: 10 pages, 4 figures; more details/discussion added to the text,
references added/updated, version to appear in Advances in High Energy
Physics for the Special Issue "Physics at a Fixed-Target Experiment Using the
LHC Beams
Probing the three-gluon correlation functions by the single spin asymmetry in p^\uparrow p\to DX
We study the single transverse-spin asymmetry for the inclusive open-charm
production in the pp-collision, p^\uparrow p\to DX, induced by the three-gluon
correlation functions in the polarized nucleon. We derive the corresponding
twist-3 cross section formula in the leading order with respect to the QCD
coupling constant. As in the case of the semi-inclusive deep inelastic
scattering, ep^\uparrow\to eDX, our result differs from the previous result in
the literature. We also derive a "master formula" which expresses the twist-3
cross section in terms of the gg\to c\bar{c} hard scattering cross section. We
present a model calculation of the asymmetry at the RHIC energy, demonstrating
the sensitivity of the asymmetry on the form of the three-gluon correlation
functions.Comment: 25 pages, 7 figures. Final version to appear in PRD. Some changes in
the section of numerical calculation include
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