119329204
Lattice Gross-Neveu model with domain-wall fermions
Abstract We investigate the two-dimensional lattice Gross-Neveu model, using the domain-wall fermion formulation, as a toy model of lattice QCD. We study features of the phase diagram related to the mechanism of chiral symmetry restoration, and find that the parity-broken phase (Aoki phase) exists for finite extent in the extra dimension ( N s ). We also find that O ( a ) scaling violation terms vanishes in the limit of N s → ∞.
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.
123766610
The KMI Lattice Project — Exploring for Technicolor from QCD
It is well known that the SU(3) gauge theory with the fundamental 16-flavor fermion is governed by a nontrivial infrared fixed point in the 2-loop perturbation theory, while the theory has not been well investigated by non-perturbative lattice simulations. We investigate properties of 16-flavor QCD by lattice simulation with highly improved action setup(HISQ/tree) at two lattice spacings. We present preliminary results for the mass of the lightest pseudoscalar meson, and its decay constant at non-zero fermion mass. We discuss the finitemass and finite-volume scaling of the quantities, the mass anomalous dimension extracted from the scaling, and comparison of the anomalous dimension with the perturbation theory.
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.
3243998
Testing topology conserving gauge actions for Lattice QCD
We explore gauge actions for lattice QCD, which are constructed such that the occurrence of small plaquette values is strongly suppressed. Such actions orig inate from the admissibility condition in order to conserve the topological charge. The suppression of small plaquette values is expected to be advantageous for numerical studies in the e-regime and also for simulations with dynamical quarks. Performing simulations at a lattice spacing of about 0.1 fm, we present numerical results for the static potential, the physical scale r0, the stability of the topological charge history, the condition number of the kernel of the overlap operator and the acceptance rate against the step size in the local HMC algorithm.
15136419
Going chiral: Overlap versus twisted mass fermions
We compare the behavior of overlap fermions, which are chirally invariant, and of Wilson twisted mass fermions at full twist in the approach to the chiral limit. Our quenched simulations reveal that with both formulations of lattice fermions pion masses of (250 MeV) can be reached in practical applications. Our comparison is done at a fixed value of the lattice spacing a 0.123 fm. A number of quantities are measured such as hadron masses, pseudoscalar decay constants and quark masses obtained from Ward identities. We also determine the axial vector renormalization constants in the case of overlap fermions.
10281433
Evaluation of test structures for the novel n + -in-p pixel and strip sensors for very high radiation environments
Abstract Radiation-tolerant n + -in-p silicon sensors were developed for use in very high radiation environments. Novel n + -in-p silicon strip and pixel sensors and test structures were fabricated, tested and evaluated, in order to understand the designs implemented. The resistance between the n + implants (interstrip resistance), the electric potential of the p-stop, and the punch-through-protection (PTP) onset voltage were measured before and as a function of fluence after irradiation. The technology computer-aided design (TCAD) simulations were used to understand the radiation damage and fluence dependence of the structures. The decrease in the interstrip resistance is a consequence of increased leakage current. The decrease in the electric potential of the p-stop results from a build-up of positive charge in the silicon–silicon oxide interface. The decrease and subsequent increase in the PTP onset voltages results from the interface charge build-up and an increase in acceptor states.