39881433
Equation of state for pure SU(3) gauge theory with renormalization group improved action
A lattice study of the equation of state for pure SU~3! gauge theory using a renormalization-group ~RG! improved action is presented. The energy density and pressure are calculated on a 16 3 3 4a nd a3 2 3 38 lattice employing the integral method. Extrapolating the results to the continuum limit, we find the energy density and pressure to be in good agreement with those obtained with the standard plaquette action within the error of 3-4 %.@S0556-2821~99!07819-4# In this article we report on our study of the continuum limit of the equation of state for pure SU~3! gauge theory with an improved action determined from an approximate renormalization-group argument @7#. Simulations are carried out on 16 3 34 and 32 3 38 lattices, and the energy density and pressure are calculated by the integral method @8# .W e find that the results extrapolated to the continuum limit agree well with those obtained from the standard action in Ref. @2#. This provides us with a crosscheck of the final results in the continuum limit, and also provide support for the validity of assumptions behind the extrapolation procedures. This paper is organized as follows. In Sec. II, we summa- rize the basic formulation and our notations. Some details of our simulations are given in Sec. III. We define our choice of the temperature scale in terms of the string tension in Sec. IV, and examine scaling of the critical temperature in Sec. V. In Sec. VI we present our results for equation of state ob- tained at Nt54 and 8, and their continuum extrapolation. A comparison of our results with those obtained from the stan- dard action is also made. In Sec. VII we briefly discuss re- sults obtained with the operator method @9#. We end with a brief conclusion in Sec. VIII.
26599771
Sea quark effects on quarkonia
We study the effects of two dynamical sea quarks on the spectrum of heavy quarkonia. Within the non-relativistic approach to Lattice QCD we found sizeable changes to the hyperfine splitting, but we could not observe any changes for the fine structure. We also investigated the scaling behaviour of our results for several different lattice spacings.
14619672
Chiral zero modes on the Domain Wall model in (4+1)-dimensions
We investigate an original domain-wall model in 4+1 dimensions numerically in the presence of U(1) dynamical gauge field only in an extra dimension, corresponding to a weak coupling limit of four-dimensional physical gauge coupling. Using a quenched approximation we carry out a numerical simulation for this model at ${\ensuremath{\beta}}_{s}{(=1/g}_{s}^{2})=$ 0.29 (``symmetric'' phase) and 0.5 (``broken'' phase), where ${g}_{s}$ is the gauge coupling constant of the extra dimension. In the broken phase, we found that there exists a critical value of a domain-wall mass ${m}_{0}^{c}$ which separates a region with a fermionic zero mode on the domain wall from the one without it in the same case of (2+1)-dimensional model. On the other hand, in the symmetric phase, our numerical data suggest that the chiral zero modes disappear in the infinite limit of four-dimensional volume. From these results it seems difficult to construct the U(1) lattice chiral gauge theory via an original domain-wall formulation.
5379081
Scaling test of fermion actions in the Schwinger model
Abstract We discuss the scaling behaviour of different fermion actions in dynamical simulations of the 2-dimensional massive Schwinger model. We have chosen Wilson, hypercube, twisted mass and overlap fermion actions. As physical observables, the pion mass and the scalar condensate are computed for the above mentioned actions at a number of coupling values and fermion masses. We also discuss possibilities to simulate overlap fermions dynamically avoiding problems with low-lying eigenvalues of the overlap kernel.
16533811
Two-dimensional lattice Gross-Neveu model with Wilson twisted mass fermions
Abstract We study the two-dimensional lattice Gross–Neveu model with Wilson twisted mass fermions in order to explore the phase structure in this setup. In particular, we investigate the behaviour of the phase transitions found earlier with standard Wilson fermions as a function of the twisted mass parameter μ . We find that qualitatively the dependence of the phase transitions on μ is very similar to the case of lattice QCD.
119024751
Light Hadron Spectroscopy with Two Flavors of Dynamical Quarks on the Lattice
~CP-PACS Collaboration ! Center for Computational Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan Institute of Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8571, Japan Institute for Cosmic Ray Research, University of Tokyo, Kashiwa 277-8582, Japan High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan ~Received 18 May 2001; published 5 February 2002 !
118607823
Surface Majorana cone of the superfluid 3He B phase
The superfluid 3 He B phase, one of the oldest unconventional fermionic condensates experimentally realized, is recently predicted to support Majorana fermion surface states. Majorana fermion, which is characterized by the equivalence of particle and antiparticle, has a linear dispersion relation referred to as the Majorana cone. We measured the transverse acoustic impedance Z of the superfluid 3 He B phase changing its boundary condition and found a growth of peak in Z on a higher specularity wall. Our theoretical analysis indicates that the variation of Z is induced by the formation of the cone-like dispersion relation and thus confirms the important feature of the Majorana fermion in the specular limit.