5,039 research outputs found
Single Transverse-Spin Asymmetry in Large Open Charm Production at an Electron-Ion Collider
We discuss the single transverse-spin asymmetry (SSA) to be observed in the
-meson production with large transverse-momentum in semi-inclusive deep
inelastic scattering, . 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 -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
muSR study of the Cu-spin dynamics in the electron-doped high-Tc cuprate of Pr0.86LaCe0.14Cu1-y(Zn,Ni)yO4
Effects of the Zn- and Ni-substitution on the Cu-spin dynamics in the
electron-doped Pr0.86LaCe0.14Cu1-y(Zn,Ni)yO4+a-d with y = 0, 0.01, 0.02, 0.05
and different values of the reduced oxygen content d have been studied using
zero-field muon-spin-relaxation (muSR) measurements at temperatures down to 2
K. For the as-grown sample (d = 0, y = 0) and the sample with a very small d
value (d < 0.01, y = 0), a muon-spin precession due to long-range
antiferromagnetic order has been observed. On the other hand, no precession has
been observed for moderately oxygen-reduced samples (0.01 < d < 0.09). It has
been found that for all the samples of 0.01 < d < 0.09 the asymmetry A(t) (muSR
time spectrum) in the long-time region increases with decreasing temperature at
low temperatures, suggesting possible slowing-down of the Cu-spin fluctuations.
On the other hand, no significant difference between Zn- and Ni-substitution
effects on the slowing down of the Cu-spin fluctuations has been observed.Comment: 4 pages, 2 figures, Proceeding of 10th muSR conference 2005, to be
published in Physica
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
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
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
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
Cu-spin dynamics in the overdoped regime of La_2-x_Sr_x_Cu_1-y_Zn_y_O_4_ probed by muon spin relaxation
Muon-spin-relaxation measurements have been performed for the partially
Zn-substituted La_2-x_Sr_x_Cu_1-y_Zn_y_O_4_ with y=0-0.10 in the overdoped
regime up to x=0.30. In the 3 % Zn-substituted samples up to x=0.27,
exponential-like depolarization of muon spins has been observed at low
temperatures, indicating Zn-induced slowing-down of the Cu-spin fluctuations.
The depolarization rate decreases with increasing x and almost no fast
depolarization of muon spins has been observed for x=0.30 where
superconductivity disappears. The present results suggest that the dynamical
stripe correlations exist in the whole superconducting regime of
La_2-x_Sr_x_CuO_4_ and that there is no quantum critical point at x~0.19.Comment: 6 pages, 5 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 -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
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