Improving the Lattice QCD Hamiltonian
Improvement of the Hamiltonian in lattice gauge theory is considered. We give explicit expressions for classical improvement and discuss also quantum corrections.
hep-lat↗
arXiv subjects
Xiang-Qian Luo
Publications and source records attributed to Xiang-Qian Luo.
Simulating the vacuum properties of QCD with dynamical quarks
The vacuum properties of lattice QCD with staggered quarks are investigated by an efficient simulation method. I present data for the quark condensate with flavor number $N_f=0, ~ 1, ~ 2, ~ 3, ~ 4$ and many quark masses, including the vacuum energy in the chiral limit. Obvious sea quark effects are observed in some parameter space. I also describe a mechanism to understand this and a formula relating the chiral condensate and zero modes.
hep-lat↗
Recent Advances in Hamiltonian Lattice Gauge Theory
We review the recent advances in the Hamiltonian formulation of lattice gauge theory for approaching the continuum physics. In particular, vacuum wave function and glueball spectrum calculations by coupled cluster method with truncation scheme preserving the continuum behavior are described.
hep-lat↗
Glueball Masses from Hamiltonian Lattice QCD
We calculate the masses of the $0^{++}$, $0^{--}$ and $1^{+-}$ glueballs from QCD in 3+1 dimensions using an eigenvalue equation method for Hamiltonian lattice QCD developed and described elsewhere by the authors. The mass ratios become approximately constants in the coupling region $6/g^2 \in [6.0,6.4]$, from which we estimate $M(0^{--})/M(0^{++})=2.44 \pm 0.05 \pm 0.20$ and $M(1^{+-})/M(0^{++})=1.91 \pm 0.05 \pm 0.12$.
hep-ph↗
Glueball Masses in Quantum Chromodynamics
We review the recent glueball mass calculations using an efficient method for solving the Schrödinger equation order by order with a scheme preserving the continuum limit. The reliability of the method is further supported by new accurate results for (1+1)-dimensional $σ$ models and (2+1)-dimensional non-abelian models. We present first and encouraging data for the glueball masses in 3+1 dimensional QCD.
hep-ph↗
Investigation of spontaneous symmetry breaking from a non standard approach
We propose a new method for the study of the chiral properties of the ground state in Quantum Field Theories (QFT's) which is based on the computation of the probability distribution function (p.d.f.) of the chiral condensate in the chiral limit. We show how despite of the fact that Grassmann variables cannot be simulated on a computer, an analysis of spontaneous symmetry breaking without a symmetry breaking external field, which is standard in the case of spin systems, can also be done in QFT's with fermion degrees of freedom.
hep-lat↗
Estimate for the $0^{++}$ glueball mass in QCD
We obtain accurate result for the lightest glueball mass of QCD in 3 dimensions from lattice Hamiltonian field theory. Using the dimensional reduction argument, a good approximation for confining theories, we suggest that the $0^{++}$ glueball mass in 3+1 dimensional QCD be about $1.71$ GeV.
hep-ph↗
Spontaneous Symmetry Breaking in Fermion-Gauge Systems- A Non Standard Approach
We propose a new method for the study of the chiral properties of the ground state in QFT's based on the computation of the probability distribution function of the chiral condensate. It can be applied directly in the chiral limit and therefore no mass extrapolations are needed. Furthermore this approach allows to write up equations relating the chiral condensate with quantities computable by standard numerical methods, the functional form of these relations depending on the broken symmetry group. As a check, we report some results for the compact Schwinger model.
hep-th↗
QCD_3 Vacum Wave Function
We investigate quantum chromodynamics in 2+1 dimensions ($\rm{QCD}_3$) using the Hamiltonian lattice field theory approach. The long wavelength structure of the ground state, which is closely related to the confinement phenomenon, is analyzed and its vacuum wave function is evaluated by means of the recently developed truncated eigenvalue equation method. The third order estimations show nice scaling for the physical quantities.
hep-th↗
Glueball Masses in QCD_3
We discuss how to extract the spectroscopy of quantum chromodynamics (QCD) in the pure gauge sector from the Hamiltonian lattice field theory approach. The recently developed truncated eigenvalue equation method is applied to the estimation of the scalar glueball $0^{++}$ and $0^{--}$ masses in the (2+1)-dimensional case. These masses reach the constant values in a scaling region as required by the renormalizability.
hep-ph↗
Spectrum and scaling in a strongly coupled fermion-gauge-scalar model
The strongly coupled lattice gauge models show an interesting mechanism of dynamical mass generation. If a suitable continuum limit can be found, one may think of it as an alternative to the Higgs mechanism. We present data on the spectrum, obtained in the model with U(1) gauge symmetry with dynamical fermions. They indicate that the fermion mass scales in the vicinity of the whole chiral phase transition line. In contrast to this, the composite scalar boson mass seems to get small only in the region near the endpoint E of the Higgs phase transition. Thus this point is the most interesting candidate for approaching the continuum limit. The masses of fermion--antifermion bound states are also discussed.
hep-lat↗
Chiral transition in a strongly coupled fermion-gauge-scalar model
We report the recent results from the computer simulations of a fermion-gauge-scalar model with dynamical chiral-symmetry breaking and chiral transition induced by the scalar field. This model might be considered to be a possible alternative to the Higgs mechanism of mass generation. A new scheme is developed for detecting the chiral transition. Our results show with higher precision than the earlier works that the chiral transition line joins the Higgs phase transition line, separating the Higgs and Nambu (chiral-symmetry breaking) phases. The end point of the Higgs transition with divergent correlation lengths is therefore suitable for an investigation of the continuum limit.
hep-lat↗