Theoretical Physics

N* masses from an anisotropic lattice QCD action

We report N* masses in the spin-3 2 sector from a highly-improved anisotropic action. States with both positive and negative parity are isolated via a parity projection method. The extent to which spin projection is needed is examined. The gross …

Quenched charmonium near the continuum limit

We study relativistic charmonium on very fine quenched lattices (β = 6.4 and 6.6). We concentrate on the calculation of the hyperfine splitting between ηc and J/ψ, aiming for a controlled continuum extrapolation of this quantity. Results for the ηc …

Screening mass responses to chemical potential at finite temperature

Responses to chemical potential of the pseudoscalar meson screening mass and the chiral condensate in lattice QCD are investigated. On a 16 × 82 × 4 lattice with two flavors of staggered quarks the first and second responses below and above Tc are …

Lattice tool kit in Fortran90

We report a project to provide a set of free source codes for lattice QCD. The programs may be used as fundamental blocks when one wants to construct his/her own QCD codes. They are written in Fortran 90 with use of MODULE, so that algorithms can …

∂m/∂μ in the Nambu-Jona-Lasinio model

Using the Nambu-Jona-Lasinio (NJL) model we study responses of the pion and kaon masses to changes in the chemical potential, ∂m/∂μ, at zero and finite chemical potential. We find that the behavior of ∂m/∂μ for the pion is quite different from that …

Responses of hadrons to the chemical potential at finite temperature

We present a framework to compute the responses of hadron masses to the chemical potential in lattice QCD simulations. As a first trial, the screening mass of the pseudoscalar meson and its first and second responses are evaluated. We present results …

Nucleon resonance phenomenology from lattice QCD

The CLAS program at Jefferson Lab will focus on the low-lying odd-parity spin-1/2 and 3/2 baryon resonances of the nucleon. These baryons offer an interesting forum for investigating QCD and model predictions. Lattice QCD investigations of the …

Kaon-baryon coupling constants in the QCD sum rule approach

We improve our previous QCD sum rule calculation on g KN Λ and g KN Σ coupling constants by including the contributions from higher dimensional condensates,and, in the OPE. It is found that the contribution of these condensates is non-negligible …

Multiquark picture for Σ (1620)

In this work we report on a new QCD sum rule analysis to predict masses of the excited baryon states (e.g. Σ (1620) and Λ (1405)) by using multiquark interpolating fields ((q¯q)(qqq)). For the Σ (1620) we consider the ¯KN, πΣ, and πΛ (I = 1) …

Multiquark picture for Lambda (1405) and Sigma (1620)

We propose a new QCD sum rule analysis for the Λ (1405) and the Σ (1620). Using the I=0 and I=1 multiquark sum rules we predict their masses.