36350052
Time reversal invariance violation in neutron-deuteron scattering
Time reversal invariance-violating (TRIV) effects in low-energy elastic neutron-deuteron scattering are calculated using meson exchange and EFT-type TRIV potentials in a distorted-wave Born approximation with realistic hadronic strong interaction wave functions, obtained by solving the three-body Faddeev equations in configuration space. The relation between TRIV and parity-violating observables is discussed.
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%.
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.
32868444
Parity violation in low-energy neutron-deuteron scattering
Parity violating effects for low energy elastic neutron deuteron scattering are calculated for DDH and EFT-type of weak potentials in a Distorted Wave Born Approximation, using realistic hadronic strong interaction wave functions, obtained by solving three-body Faddeev equations in configuration space. The results of relation between physical observables and low energy constants can be used to fix low energy constants from experiments. Potential model dependencies of parity violating effects are discussed.
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.
122827874
Time Reversal Invariance Violating and Parity Conserving effects in Neutron Deuteron Scattering
Time reversal invariance violating and parity conserving effects for low-energy elastic neutron-deuteron scattering are calculated for meson exchange and effective field theory type potentials in a distorted wave-born approximation using realistic hadronic wave functions, obtained by solving three-body Faddeev equations in configuration space.
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].
119216515
Shear and bulk viscosities of a weakly coupled quark gluon plasma with finite chemical potential and temperature: Leading-log results
We calculate the shear (eta) and bulk (zeta) viscosities of a weakly coupled quark gluon plasma at the leading-log order with finite temperature T and quark chemical potential mu. We find that the shear viscosity to entropy density ratio eta/s increases monotonically with mu and eventually scales as (mu/T)^2 at large mu. In contrary, zeta/s is insensitive to mu. Both eta/s and zeta/s are monotonically decreasing functions of the quark flavor number N_f when N_f \geq 2. This property is also observed in pion gas systems. Our perturbative calculation suggests that QCD becomes the most perfect (i.e. with the smallest eta/s) at mu=0 and N_f = 16 (the maximum N_f with asymptotic freedom). It would be interesting to test whether the currently smallest eta/s computed close to the phase transition with mu=0 and N_f = 0 can be further reduced by increasing N_f.
118720520
Twist-4 contributions to the azimuthal asymmetry in SIDIS
We calculate the differential cross section for the unpolarized semi-inclusive deeply inelastic scattering (SIDIS) process e +N → e + q+X in leading order (LO) of perturbative QCD and up to twist-4 in power corrections and study in particular the azimuthal asymmetry 〈cos 2φ〉. The final results are expressed in terms of transverse momentum dependent (TMD) parton matrix elements of the target nucleon up to twist-4. We also apply it to e+A → e+q+X and illustrate numerically the nuclear dependence of the azimuthal asymmetry 〈cos 2φ〉 by using a Gaussian ansatz for the TMD parton matrix elements.
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.
15149403
Notes from the Underground: A Propos of Givental's Conjecture
These brief notes record our puzzles and findings surrounding Givental's recent conjecture which expresses higher genus Gromov-Witten invariants in terms of the genus-0 data. We limit our considerations to the case of a projective line, whose Gromov-Witten invariants are well-known and easy to compute. We make some simple checks supporting his conjecture.