5,783 research outputs found
Probing the twist-3 multi-gluon correlation functions by pp \to DX
We study the single spin asymmetry (SSA) for the D-meson production
in the collision, , in the framework of the collinear
factorization. Since the charm quark is mainly produced through the
-pair creation from the gluon-fusion process, this is an ideal
process to probe the twist-3 triple-gluon correlation functions in the
polarized nucleon. We derive the corresponding cross section formula for the
contribution of the triple-gluon correlation function to in , applying the method developed for in our
previous study. As in the case of , our result differs from
a previous study in the literature. We will also present a simple estimate of
the triple-gluon correlation functions based on the preliminary data on
by RHIC.Comment: to appear in the proceedings of the 19th International Spin Physics
Symposium (Spin2010), Sept.27 - Oct.2, 2010, Juelich, Germany, 5 pages, 2
figure
A new screening function for Coulomb renormalization
We introduce a new screening function which is useful for the few-body
Coulomb scattering problem in ``screening and renormalization'' scheme. The new
renormalization phase factor of the screening function is analytically shown.
The Yukawa type of the screening potential has been used in several decades, we
modify it to make more useful. As a concrete example, we compare the
proton-proton scattering phase shifts calculated from these potentials. The
numerical results document that high precision calculations of the
renormalization are performed by the new screening function.Comment: 4 pages, 8 figure
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
Complex Energy Method for Scattering Processes
A method for solving few-body scattering equations is proposed and examined.
The solution of the scattering equations at complex energies is analytically
continued to get scattering T-matrix with real positive energy. Numerical
examples document that the method works well for two-nucleon scattering and
three-nucleon scattering, if the set of complex energies is properly chosen.Comment: 6 pages, no figures, resubmitted to Prog. Theor. Phy
N=2 Supermultiplet of Currents and Anomalous Transformations in Supersymmetric Gauge Theory
We examine some properties of supermultiplet consisting of the U(1)_{J}
current, extended supercurrents, energy-momentum tensor and the central charge
in N=2 supersymmetric Yang-Mills theory. The superconformal improvement
requires adding another supermultiplet beginning with the U(1)_{R} current. We
determine the anomalous (quantum mechanical) supersymmetry transformation
associated with the central charge and the energy-momentum tensor to one-loop
order.Comment: 8 pages, LaTe
Dynamics of compact homogeneous universes
A complete description of dynamics of compact locally homogeneous universes
is given, which, in particular, includes explicit calculations of Teichm\"uller
deformations and careful counting of dynamical degrees of freedom. We regard
each of the universes as a simply connected four dimensional spacetime with
identifications by the action of a discrete subgroup of the isometry group. We
then reduce the identifications defined by the spacetime isometries to ones in
a homogeneous section, and find a condition that such spatial identifications
must satisfy. This is essential for explicit construction of compact
homogenoeus universes. Some examples are demonstrated for Bianchi II, VI,
VII, and I universal covers.Comment: 32 pages with 2 figures (LaTeX with epsf macro package
Weak coupling d-wave BCS superconductivity and unpaired electrons in overdoped La_{2-x}Sr_{x}CuO_{4} single crystals
The low-temperature specific heat (SH) of overdoped La_{2-x}Sr_{x}CuO_{4}
single crystals (0.178=<x=<0.290) has been measured. For the superconducting
samples (0.178=<x=<0.238), the derived gap values (without any adjusting
parameters) approach closely onto the theoretical prediction
\Delta_{0}=2.14k_{B}T_{c} for the weak-coupling d-wave BCS superconductivity.
In addition, the residual term \gamma(0) of SH at H=0 increases with x
dramatically when beyond x~0.22, and finally evolves into the value of a
complete normal metallic state at higher doping levels, indicating growing
amount of unpaired electrons. We argue that this large \gamma(0) cannot be
simply attributed to the pair breaking induced by the impurity scattering,
instead the phase separation is possible.Comment: 6 pages, 6 figures; Contents added; Accepted for publication in Phys.
Rev.
Separability of a Low-Momentum Effective Nucleon-Nucleon Potential
A realistic nucleon-nucleon potential is transformed into a low-momentum
effective one (LMNN) using the Okubo theory. The separable potentials are
converted from the LMNN with a universal separable expansion method and a
simple Legendre expansion. Through the calculation of the triton binding
energies, the separability for the convergence of these ranks is evaluated. It
is found that there is a tendency for the lower momentum cutoff parameter
of LMNN to gain good separability.Comment: 6 pages, 1 tabl
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