Related papers: The pentaquark potential, mass and density-density…
We study quenched QCD at finite chemical potential, $\mu_I$, for the third component of isospin and quenched two-colour QCD at finite chemical potential, $\mu$, for quark number. In contrast to the quenched approximation to QCD at finite…
We propose S=+1 baryon interpolating operators, which are based on an exotic description of the antidecuplet baryon like diquark-diqaurk-antiquark. By using one of the new operators, the mass spectrum of the spin-1/2 pentaquark states is…
We calculate the width of the Theta(1540) pentaquark in a relativistic model in which the pentaquark is considered to be composed of a scalar diquark and a spin 1/2 triquark. We consider both positive and negative parity for the pentaquark.…
We use a random matrix model to study chiral symmetry breaking in QCD at finite chemical potential $\mu$. We solve the model and compute the eigenvalue density of the Dirac matrix on a complex plane. A naive ``replica trick'' fails for…
We study the $\bar b \bar b u d$ tetraquark with quantum numbers $I(J^P) = 0(1^+)$ as well as the $\bar b \bar b u s$ tetraquark with quantum numbers $J^P = 1^+$ using lattice QCD. We improve on existing work by including both local and…
Quenched QCD simulations on three volumes, $8^3 \times$, $12^3 \times$ and $16^3 \times 32$ and three couplings, $\beta=5.7$, 5.85 and 6.0 using domain wall fermions provide a consistent picture of quenched QCD. We demonstrate that the…
We investigate the pentaquark system $qqqs \bar q$ in a framework of chiral quark model. Two structures, $(qqq)(s\bar{q})$ and $(qqs)(q\bar{q})$, with all possible color, spin, flavor configurations are considered. The calculations show…
Using the effective theory pNRQCD we determine the potential energy of a color singlet quark-antiquark pair with (fixed) distance r in three space-time dimensions at weak coupling (alpha r << 1). The precision of our result reaches…
The pentaquark width is calculated in QCD sum rules. Result for $\Gamma_{\Theta}$ show, that $\Gamma_{\Theta}$ can vary in the region less than 1$MeV$. The main conclusion is, that if pentaquark is genuine states then sum rules really…
Continuing our investigations of quenched QCD with improved fermions we have started simulations for lattice size 32^3 x 64 at beta=6.2. We present first results for light hadron masses at kappa=0.13520, 0.13540, and 0.13555. Moreover we…
We perform the first study for the heavy-heavy-light quark (QQq) potential in SU(3) lattice QCD. The calculations are done with the standard gauge and $O(a)$-improved Wilson fermion action on the $16^4$ lattice at $\beta =6.0$ at the…
We present our latest results for the the complex valued static heavy-quark potential at finite temperature from lattice QCD. The real and imaginary part of the potential are obtained from the position and width of the lowest lying peak in…
We present new linear relations among the masses of S-wave tetraquarks with either one flavour ($QQ \bar Q \bar Q$) or two ($QQ\bar q \bar q$). Because the relations are sensitive to the hidden-colour, spin, and spatial degrees of freedom,…
The dependence of the pseudoscalar meson mass and decay constant is compared to one-loop Partially Quenched Chiral Perturbation Theory (PQChPT) in a numerical simulation with two light dynamical quarks. The characteristic behaviour with…
Motivated by the recent experimental discoveries of multi-quark candidates, e.g., the $\Theta^+(1540)$, we study multi-quark systems in lattice QCD. First, we perform accurate mass measurements of low-lying 5Q states with $J=1/2$ and I=0 in…
The analysis of the sum rules (for two differentchoices of 5-quark currents) indicate that to explain experimental results it is necessary to have some one-particle lower state (and pentaquark is a reliable candidate to this state) while…
Anti-decuplet penta-quark baryon is studied with the quenched anisotropic lattice QCD for accurate measurement of the correlator. Both the positive and negative parity states are studied using a non-NK type interpolating field with I=0 and…
We propose a string theory construction for the system of two heavy quarks and two light antiquarks. The potential of the system is a function of separation between the quarks. We define a critical separation distance below which the system…
We compute the mass of the charm quark using both quenched and dynamical lattice QCD calculations. We examine the effects of mass dependent lattice artifacts by comparing two different formalisms for the heavy quarks. We take the continuum…
We investigate the mass spectra of $\Theta^+(udud\bar s)$ in quenched lattice QCD, with overlap and Wilson fermions respectively. Using three different interpolating operators, we measure their correlation matrix, and extract the mass…