118602952
Hidden conformal symmetry of extremal Kaluza-Klein black hole in four dimensions
We study the hidden conformal symmetry of four-dimensional extremal Kaluza-Klein black hole. The scalar Laplacian corresponding to the radial equation in the near-region is rewritten in terms of the $ {\text{SL}}\left( {2,\mathbb{R}} \right) $ quadratic Casimir. Using the first law of black hole thermodynamics, this symmetry enables us to obtain the conjugate charges for the CFT side. The real-time correlators are also found to agree with the CFT expectations.
119273979
Entropic corrections and modified Friedmann equations in the emergence of cosmic space
In the emergent cosmic space scenario recently proposed by Padmanabhan, the expansion of the universe is attributed to the difference between the number of degrees of freedom on a holographic surface and the one in the bulk. Based on this idea, we explore the cases where logarithmic and power-law entropic corrections are present, respectively. The previously found modified Friedmann equations are reproduced through an improved proposal, and we show that the same results can be obtained using a generalized expansion law.
118650355
Observation concerning the process dependence of the Sivers functions
The k{sub perpendicular} moment of a quark's Sivers function is known to be related to the corresponding twist-three quark-gluon correlation function T{sub q,F}(x,x). The two functions have been extracted from data for single-spin asymmetries in semi-inclusive deep-inelastic scattering and in single-inclusive hadron production in pp collisions, respectively. Performing a consistent comparison of the extracted functions, we find that they show a ''sign mismatch'': while the magnitude of the functions is roughly consistent, the k{sub perpendicular} moment of the Sivers function has opposite sign from that of T{sub q,F}(x,x), both for up and for down quarks. Barring any inconsistencies in our theoretical understanding of the Sivers functions and their process dependence, the implication of this mismatch is that either the Sivers effect is not dominantly responsible for the observed single-spin asymmetries in pp collisions or the current semi-inclusive lepton scattering data do not sufficiently constrain the k{sub perpendicular} moment of the quark Sivers functions. Both possibilities strengthen the case for further experimental investigations of single-spin asymmetries in high-energy pp and ep scattering.
121699906
Two particle correlations: Saturation and issues with universality
Abstract We study the universality issue of the transverse momentum dependent parton distributions at small- x , by comparing the initial/final state interaction effects in di-jet correlation in pA collisions with those in deep inelastic lepton–nucleus scattering. We demonstrate the non-universality by performing an explicit calculation in a particular model where the multiple gauge boson exchange contributions are summed up to all orders. In addition, we generalize the model calculation to the CGC formalism, and find the non-universality for quark distributions in CGC.
7457778
Enhanced minijet production in A–A collisions from gluons with large transverse momenta
Abstract We find supersaturation for the intrinsic gluon distribution of nuclei, i.e., the low x unintegrated nuclear gluon distribution peaks at intermediate transverse momenta k t = Q s and vanishes at zero k t . Taking into account the intrinsic transverse momenta of the gluons and the saturation scale p s of the produced gluons, we calculate the minijet cross section arising from gluon gluon scattering for RHIC energies. For central collisions at s =200  GeV the saturation scale p s ≈1.4 GeV is larger due to intrinsic k t effects and increases with energy. Our theoretical results on charged particle multiplicity agree very well with the recent experimental data from RHIC.
118410172
On the Relation Between Mechanisms for Single-Transverse-Spin Asymmetries
Recent studies have shown that two widely-used mechanisms for single-transverse-spin asymmetries based on either twist-three contributions or on transverse-momentum-dependent (Sivers) parton distributions become identical in a kinematical regime of overlap. This was demonstrated for the so-called soft-gluon-pole and hard-pole contributions to the asymmetry associated with a particular quark-gluon correlation function in the nucleon. In this paper, using semi-inclusive deep inelastic scattering as an example, we extend the study to the contributions by soft-fermion poles and by another independent twist-three correlation function. We find that these additional terms organize themselves in such a way as to maintain the mutual consistency of the two mechanisms for single-spin asymmetries.