49577145
Neutrino deuteron scattering in effective field theory at next-to-next-to-leading order
We study the four channels associated with neutrino-deuteron breakup reactions at next-to-next-to-leading order in effective field theory. We find that the total cross section is indeed converging for neutrino energies up to 20 MeV, and thus our calculations can provide constraints on theoretical uncertainties for the Sudbury Neutrino Observatory. We stress the importance of a direct experimental measurement to high precision in at least one channel, in order to fix an axial two-body counterterm.
119272530
Model analysis of thermal UV-cutoff effects on the chiral critical surface at finite temperature and chemical potential
We study the effects of temporal UV-cutoff on the chiral critical surface in hot and dense QCD using a chiral effective model. Recent lattice QCD simulations indicate that the curvature of the critical surface might change toward the direction in which the first-order phase transition becomes stronger on increasing the number of lattice sites. To investigate this effect on the critical surface in an effective model approach, we use the Nambu-Jona-Lasinio model with finite Matsubara frequency summation. We find that the nature of the curvature of the critical surface does not alter appreciably as we decrease the summation number, which is unlike the case that was observed in recent lattice QCD studies. This may suggest that the dependence of chemical potential on the coupling strength or some additional interacting terms such as vector interactions could play an important role at finite density.
119519405
Parity Violation in Polarized-Gamma Proton Compton Scattering
Polarized beam gamma p Compton scattering provides a theoretically clean way to extract the isovector parity violating pion-nucleon coupling constant $h_{\pi NN}^{(1)}$. This channel is more tractable experimentally than the recently proposed extraction of $h_{\pi NN}^{(1)}$ from the Bedaque-Savage process --- polarized target gamma p compton scattering. The leading parity violating effect is calculated using Heavy Baryon Chiral Perturbation Theory. The size of the asymmetry is estimated to be ~ 4 10^{-8} for 120 MeV photon energy.
13534760
Constructing parton convolution in effective field theory.
Parton convolution models have been used extensively in describing the sea quarks in the nucleon and explaining quark distributions in nuclei (the EMC effect). From the effective field theory point of view, we construct the parton convolution formalism which has been the underlying conception of all convolution models. We explain the significance of scheme and scale dependence of the auxiliary quantities such as the pion distributions in a nucleon. As an application, we calculate the complete leading nonanalytic chiral contribution to the isovector component of the nucleon sea.
119491739
Twisted valence quarks and hadron interactions on the lattice
Abstract We consider QCD with valence and sea quarks obeying different boundary conditions. We point out that the energy of low lying two hadron states do not depend on the boundary condition of the sea quarks (up to exponentially small corrections). Thus, the advantages in using twisted boundary conditions on the lattice QCD extraction of nucleon–nucleon phase shifts can be gained without the need of new gauge configurations, even in fully unquenched calculations.
119418730
Large-Nc quark distributions in the delta and chiral logarithms in quark distributions of the nucleon
Abstract In a world with two quark flavors and a large number of colors ( N c ), the polarized and unpolarized quark distributions in the delta are completely determined by those in the nucleon up to relative O (1/N c 2 ) . In particular, we find q Δ (x)=[(1±2T z )u N (x)+(1∓2T z )d N (x)]/2(1+ O (1/N c 2 )) and Δq Δ (x)=[(5±2T z )Δu N (x)+(5∓2T z )Δd N (x)]/10(1+ O (1/N c 2 )) , where q = u , d and T z the charge state of a delta. The result can be used to estimate the leading chiral-logarithmic corrections to the quark distributions in the nucleon.
119355216
Spectral function of rho in dense and hot hadronic matter
The spectral function of rho meson in hot/dense hadronic matter is studied by taking into account the nucleon-loop on quantum hadrondynamics model level. Different from the hot pion gas effect which changes the spectral function slightly, the nucleon-antinucleon polarization (Dirac sea) makes the spectral function very sharp and shifted towards the low invariant mass region significantly due to the decreasing effective nucleon mass.
17907752
Observation of hypertritons in Au+Au collisions at \sqrt{s_{NN}} = 200 GeV
We report preliminary results of hypertriton observation in heavy-ion collisions at RHIC. We have identified 157 +- 30 candidates in the current sample containing ~10^8 Au+Au events at \sqrt{s_{NN}} = 200 GeV. The production rate of hypertriton is close to that of helium 3. No extra penalty factor is observed for hypertriton, in contrast to results observed at the AGS.
120304704
NON-ABELIAN PERMITTIVITY OF QUARK–GLUON PLASMA DUE TO THE SELF-INTERACTION OF FIELD
From the semiclassical kinetic equations and the mean field equation of quark–gluon plasma, the contribution of the color field self-coupling to the non-Abelian permittivity at the leading order in the weak coupling constant is analyzed. The nonlinear frequency drift has been estimated for the k=0 modes.
118573990
Three-dimensional correlated-fermion phase separation from analysis of the geometric mean of the individual susceptibilities
A quasi-Gaussian approximation scheme is formulated to study the strongly correlated imbalanced Fermions thermodynamics, where the mean-field theory is not applicable. The non-Gaussian correlation effects are understood to be captured by the statistical geometric mean of the individual susceptibilities. In the three-dimensional unitary fermions ground state, a universal nonlinear scaling transformation relates the physical chemical potentials with the individual Fermi kinetic energies. For the partial polarization phase separation to full polarization, the calculated critical polarization ratio is δC = [1−(1−ξ)6/5]/[1+(1−ξ)6/5] ≐ 0.34. ξ = 4/9 gives the ratio of the symmetric ground state energy density to that of the ideal fermion gas.
122544309
THE MULTI-VALUE OF EFFECTIVE NUCLEON MASS IN HOT/DENSE NUCLEAR MATTER AND THE PHASE TRANSITION
From the Lagrangian of QHD-I model, we investigate the effective nucleon mass under the mean field approximation in a wide temperature region. The multi-solution of self-consistent equation for the effective mass in found. In the high temperature region, the relation between the multi-solutions and the phase transition is analyzed. Furthermore, the variation of energy density in this region is studied.