53708603
QCD viscosity to entropy density ratio in the hadronic phase
The shear viscosity {eta} of QCD in the hadronic phase is computed by the coupled Boltzmann equations of pions and nucleons in low temperatures and low baryon-number densities. The {eta} to entropy density ratio {eta}/s maps out the nuclear gas-liquid phase transition by forming a valley tracing the phase transition line in the temperature-chemical potential plane. When the phase transition turns into a crossover, the {eta}/s valley gradually disappears. We suspect the general feature for a first-order phase transition is that {eta}/s has a discontinuity in the bottom of the {eta}/s valley. The discontinuity coincides with the phase transition line and ends at the critical point. Beyond the critical point, a smooth {eta}/s valley is seen. However, the valley could disappear further away from the critical point. The {eta}/s measurements might provide an alternative to identify the critical points.
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.
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.
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.
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.
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.
120698543
The nonlinear spatial damping rate in QGP
Abstract The derivative expansion method has been used to solve the semiclassical kinetic equations of quark-gluon plasma. The nonlinear spatial damping rate, the imaginary part of the wave vector, for the longitudinal secondary color waves in the long wavelength limit has been calculated numerically.
122688615
Search for Minimum Universal Extra Dimensions with Four Leptons Final State at CMS
In models where extra dimensions are accessible to all particles, a new set of particles is predicted with a mass spectrum that can mimic a SUSY scenario: all Standard Model particles will have so called Kaluza‐Klein partners. Recent studies of the CMS collaboration are presented on the sensitivity to searches for the minimum universal extra dimensions with a compactification scale up to 900 GeV−1, using the 4 leptons final state. These studies are based on detailed detector simulation, including all Standard Model backgrounds.
119269362
LEPTON FLAVOR VIOLATION IN INVERSE SEESAW MODEL
We analyze the lepton flavor violation processes μ-e conversion, li→ljγ and li→3lj in framework of the Standard Model (SM) extended with inverse seesaw mechanism, as a function of that parametrizes the departure from unitary of the light neutrino mixing sub-matrix . In a wide range of , the predictions on the μ-e conversion rates and the branching ratio of μ→eγ are sizeable to be compatible with the experimental upper limits or future experimental sensitivities. For large scale of , the predictions on branching ratios of other lepton flavor processes can also reach the experimental upper limits or future experimental sensitivities. The value of depends on the determinant of the Majorana mass term Mμ. Finally, searching for lepton flavor violation processes in experiment provides us more opportunities for the searches of seesaw nature of the neutrino masses.
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.