122981735
Two-Channel Optical Model of High Energy Hadron-Nucleus Collisions
22209692
Color confinement and the Faddeev-Popov ghosts in Coulomb gauge QCD
We investigate the Gribov-Zwanziger scenario in the Coulomb gauge using a SU(3) quenched lattice gauge simulation. The dressing function of the ghost propagator diverges in the infrared limit. This result is expected from the fact that the Faddeev-Popov eigenvalue density gets concentrated near the vanishing eigenvalue compared to that in the abelian gauge theory. The turnover of the transversal gluon propagator is not observed up to the largest lattice volume explored in this study. The instantaneous part of the time-time component of the gluon propagator which corresponds to the color-Coulomb potential in the continuum limit diverges stronger than the simple pole. Furthermore, we observe that the ghost propagator show good scaling while both components of the gluon propagator do not show scaling in the considered range of the lattice spacing.
118532418
EoS of finite density QCD with Wilson fermions by multi-parameter reweighting and Taylor expansion
A bstractThe equation of state (EoS), quark number density and susceptibility at nonzero quark chemical potential μ are studied in lattice QCD simulations with a clover improved Wilson fermion of 2-flavors and RG-improved gauge action. To access nonzero μ, we employ two methods: a multi-parameter reweighting (MPR) in μ and β and Taylor expansion in μ/T. The use of a reduction formula for the Wilson fermion determinant enables to study the reweighting factor in MPR explicitly and higher-order coefficients in Taylor expansion free from errors of noise method, although calculations are limited to small lattice size. As a consequence, we can study the reliability of the thermodynamical quantities through the consistency of the two methods, each of which has different origin of the application limit. The thermodynamical quantities are obtained from simulations on a 83 × 4 lattice with an intermediate quark mass(mPS/mV = 0.8). The MPR and Taylor expansion are consistent for the EoS and number density up to μ/T ~ 0.8 and for the number susceptibility up to μ/T ~ 0.6. This implies within a given statistics that the overlap problem for the MPR and truncation error for the Taylor expansion method are negligible in these regions. In order to make MPR methods work, the fluctuation of the reweighting factor should be small. We derive the equation of the reweighting line where the fluctuation is small, and show that the equation of the reweighting line is consistent with the fluctuation minimum condition.
43999878
Scalar mesons in lattice QCD
Recently there has been renewed and growing interestin scalarmesons[1, 2]. Oneofthe mostnoteworthydevel-opments in this ﬁeld is the re-identiﬁcation of the σ(600)after some twenty years. The results of re-analyses of theπ-π scattering phase shift of the scattering (S) matrixstrongly suggest the existence of the pole of the σ mesonwith I = 0 and J
118183371
Wilson fermions with imaginary chemical potential
It is of prime interest to understand QCD at ﬁnite temperatur e and density. The lattice QCDwith a non-zero baryon density suffers from a sign problem, where the determinant of the quarkmatrix becomes complex and Monte Carlo simulations become unavailable. Because of this, it isstill challenge to understand the QCD at ﬁnite density. Seve ral approaches have been investigatedto overcome or circumvent the sign problem: multi-parameter reweighting, canonical approaches,imaginary chemical potentials, and so on.If the chemical potential is pure imaginary µ= µ
118146301
Heavy quark potential at finite imaginary chemical Potential
We investigate chemical-potential (μ) dependence of static-quark free energies in both the real and imaginary μ regions, using the clover-improved two-flavor Wilson fermion action and the renormalization-group improved Iwasaki gauge action. Static-quark potentials are evaluated from the Polyakov-loop correlator in the deconfinement phase and the imaginary μ = iμI region and extrapolated to the real μ region with analytic continuation. As the analytic continuation, the potential calculated at imaginary μ = iμI is expanded into a Taylor-expansion series of iμI/T up to 4th order and the pure imaginary variable iμI/T is replaced by the real one μR/T . At real μ , the 4th-order term weakens μ dependence of the potential sizably. Also, the color-Debye screening mass is extracted from the color-singlet potential at imaginary μ , and the mass is extrapolated to real μ by analytic continuation. The screening mass thus obtained has stronger μ dependence than the prediction of the leading-order thermal perturbation theory at both real and imaginary μ . This talk is based on [1].
123256260
Is the Stochastic Gauge-Fixing a Consistent Method for Reducible Gauge Theories?
By using the Stochastic Gauge-Fixing term derived in a previous paper, we stochastically quantize the Non-Abelian Antisymmetric Tensor Field theory as an example of the Reducible Gauge Theories. Though all the quantities are finitely computed and the induced vertex really reproduces the full ghost contributions, the uninterpretable terms still remain
119211078
Aharonov-Bohm scattering by vortices of dimensionally-reduced Yang-Mills field
If two dimensions of six-dimensional space-time are compactified, a topological configuration of Yang-Mills gauge field appears as a cosmic string in four dimensions, whose thickness is of the same order as the size of the compact space. We consider scattering of low-energy fermions by this object.