122962983
Higher Twist Contributions to the Azimuthal Asymmetries in SIDIS
This is intended to be a summary of a series of publications [1, 2, 3] carried out by our group. We showed that collinear expansion can be extended to the semi-inclusive deep inelastic scattering process e + p → e + q + X as a systematic way of studying higher twist effects. We calculated the cross section up to twist-3 level for different polarized and unpolarized cases, and obtained the azimuthal asymmetry cos in terms of gauge invariant twist-3 TMD parton correlation functions [1]. We further calculated the complete cross section up to twist-4 level for the unpolarized case, and obtained the azimuthal asymmetry cos 2 expressed in terms of gauge invariant twist-4 TMD parton correlation functions [3]. We also showed that the nuclear dependence of the TMD distributions can be obtained from the gauge link and studied the nuclear dependence of both cos and cos 2 asymmetries with a Gaussian ansatz for transverse momentum dependence of parton correlation functions [2, 3].
119164342
Negative off-diagonal conductivities in a weakly coupled quark-gluon plasma at the leading-log order
We calculate the conductivity matrix of a weakly coupled quark-gluon plasma at the leading-log order. By setting all quark chemical potentials to be identical, the diagonal conductivities become degenerate and positive, while the off-diagonal ones become degenerate but negative (or zero when the chemical potential vanishes). This means a potential gradient of a certain fermion flavor can drive backward currents of other flavors. A simple explanation is provided for this seemingly counter intuitive phenomenon. It is speculated that this phenomenon is generic and most easily measured in cold atom experiments.
7806265
Meson exchange effect on color superconductivity
We investigate the effects of pion and gluon exchanges on the formation of two-flavor color superconductivity at moderate density, � < 1GeV . The chiral quark model proposed by Manohar and Georgi containing pions as well as gluons is employed to show that the pion exchange reduces substantially the value of the superconducting gap gotten with the gluon exchange only. It turns out that the pion exchanges produce a repulsion between quark-quark pair in a spin and isospin singlet state. We suggest that the phase consisiting of pions, gluons and quarks is one of the candidates of in-medium QCD phase at moderate density.
119215813
Symmetry violations in few-body reactions: old and new approaches
Abstract As an attempt to find a way to resolve the discrepancy between calculated by traditional methods PV e_ects and the available set of experimental data, we analyze the methods of calculations of symmetry violating e_ects in fewbody nuclear systems. The overview of methods of calculations of PV and TRIV e_ects in few-body neutron induced reactions is presented with the analysis of values of calculated parameters and their accuracy.
18094401
Solar-neutrino reactions on deuteron in effective field theory
Abstract The cross sections for low-energy neutrino–deuteron reactions are calculated within heavy-baryon chiral perturbation theory employing a cut-off regularization scheme. The transition operators are derived up to next-to-next-to-next-to-leading order in the Weinberg counting rules, while the nuclear matrix elements are evaluated using the wave functions generated by a high-quality phenomenological NN potential. With the adoption of the axial-current-four-nucleon coupling constant fixed from the tritium beta decay data, our calculation is free from unknown low-energy constants. Our results exhibit a high degree of stability against different choices of the cutoff parameter, a feature which indicates that, apart from radiative corrections, the uncertainties in the calculated cross sections are less than 1%.
119028691
In-medium modification of P-wave charmonia from QCD sum rules
We investigate the changes of the masses and widths of {chi}{sub c0} and {chi}{sub c1} in hot gluonic matter near T{sub c} and in a nuclear medium using QCD sum rules. As in the previous works for the J/{psi} and {eta}{sub c}, in-medium effects are incorporated through the changes of gluon condensates. Twist-2 terms for the {sup 3}P{sub 0}({chi}{sub c0}) and {sup 3}P{sub 1}({chi}{sub c1}) are also included for the first time. The results show that larger mass shifts and width broadenings take place as compared to the S-wave states. As the critical change take place near T{sub c}, related measurements can reveal critical phenomenon in QCD.
7547091
Effective field theory approach for the M1 properties of A=2 and 3 nuclei
Abstract The magnetic moments of 2 H, 3 He and 3 H as well as the thermal neutron capture rate on the proton are calculated using heavy baryon chiral perturbation theory a la Weinberg. The M1 operators have been derived up to N 3 LO. The nuclear matrix elements are evaluated with the use of wave functions obtained by carrying out variational Monte Carlo calculations for a realistic nuclear Hamiltonian involving high-precision phenomenological potentials like Argonne Av18 and Urbana IX tri-nucleon interactions. We discuss the potential- and cutoff-dependence of the results.