4,313 research outputs found

### Single Transverse-Spin Asymmetry in Large $P_T$ Open Charm Production at an Electron-Ion Collider

We discuss the single transverse-spin asymmetry (SSA) to be observed in the
$D$-meson production with large transverse-momentum in semi-inclusive deep
inelastic scattering, $e p^\uparrow \rightarrow e D X$. This contribution is
embodied as a twist-3 mechanism in the collinear factorization, which is
induced by purely gluonic correlation inside the transversely-polarized
nucleon, in particular, by the three-gluon correlation effects. The complete
formula for the corresponding SSA in the leading-order QCD is expressed in
terms of the four independent gluonic correlation functions and reveals the
five independent structures with respect to the dependence on the azimuthal
angle for the produced $D$-meson. We present the numerical calculations of the
SSA formula at the kinematics relevant to a future Electron Ion Collider.Comment: 16 pages, 7 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, $p^\uparrow$. This
contribution is embodied as a twist-3 mechanism in the collinear factorization
framework and controls the SSA to be observed in the $D$-meson production with
large transverse-momentum in semi-inclusive DIS (SIDIS), $ep^\uparrow
\rightarrow eDX$. 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 $D$-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 $D$
meson. We also demonstrate the remarkable relation between the twist-3
single-spin-dependent cross section and twist-2 cross sections for the
$D$-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

### Muon-spin-relaxation and magnetic-susceptibility studies of effects of the magnetic impurity Ni on the Cu-spin dynamics and superconductivity in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x = 0.13

Effects of the magnetic impurity Ni on the Cu-spin dynamics and
superconductivity have been studied in La_2-x_Sr_x_Cu_1-y_Ni_y_O_4_ with x =
0.13 changing y finely up to 0.10. Compared with the case of the nonmagnetic
impurity Zn, it has been found from the muon-spin-relaxation measurements that
a large amount of Ni is required to stabilize a magnetic order of Cu spins.
However, the evolution toward the stabilization of the magnetic order with
increasing impurity concentration is qualitatively similar to each other. The
area of the non-superconducting and slowly fluctuating or static region of Cu
spins around Ni has been found to be smaller than that around Zn, suggesting
that the pinning of rather long-ranged dynamical spin correlation such as the
so-called dynamical stripe by Ni is weaker than that by Zn. This may be the
reason why Zn destroys the superconductivity in the hole-doped high-T_c_
cuprates more markedly than Ni.Comment: 4 pages, 4 figures, accepted for publication in Phys. Rev.

### Probing the twist-3 multi-gluon correlation functions by pp \to DX

We study the single spin asymmetry (SSA) for the D-meson production $A_N^D$
in the $pp$ collision, $p^\uparrow p\to DX$, in the framework of the collinear
factorization. Since the charm quark is mainly produced through the
$c\bar{c}$-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 $A_N^D$ in $p^\uparrow
p\to DX$, applying the method developed for $ep^\uparrow\to eDX$ in our
previous study. As in the case of $ep^\uparrow\to eDX$, 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 $A_N^D$
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

### 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 $pp$-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-$x$ behavior of the
correlation functions.Comment: 15 pages, 3 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

- β¦