103 research outputs found
Phase structure of 3D Z(N) lattice gauge theories at finite temperature: large-N and continuum limits
We study numerically three-dimensional Z(N) lattice gauge theories at finite
temperature, for N = 5, 6, 8, 12, 13 and 20 on lattices with temporal extension
= 2, 4, 8. For each model, we locate phase transition points and
determine critical indices. We propose also the scaling of critical points with
N. The data obtained enable us to verify the scaling near the continuum limit
for the Z(N) models at finite temperatures.Comment: 17 pages, 2 figures, 9 table
Computation of correlation matrices for tetraquark candidates with and flavor structure
The conjecture that several recently observed mesons have a structure, which
is not dominated by an ordinary quark-antiquark pair, but by a four-quark
structure, is being actively investigated both theoretical and experimentally.
Such a state may be characterized as a mesonic molecule or as a
diquark-antidiquark pair. Lattice QCD provides a theoretically sound framework
to study such states. To quantitatively investigate the internal structure of
such mesons, one needs to precisely compute correlation matrices containing
several interpolating operators including two and four quarks. Here we discuss
certain technical aspects of such correlation matrices suited to study
tetraquark candidates with and flavor structure , e.g.\ the meson, the meson and some of the
charged states. Some numerical results for the meson
are presented.Comment: 7 pages, 4 figures, talk given at the 33rd International Symposium on
Lattice Field Theory (Lattice 2015), 14-18 July 2015, Kobe International
Conference Center, Kobe, Japa
Investigation of the tetraquark candidate : technical aspects and preliminary results
We discuss technical aspects and first results of a lattice QCD study of the
state. We employ various interpolating operators of quark-antiquark,
mesonic molecule, diquark-antidiquark and two-meson type. Both connected and
disconnected contributions including diagrams with closed fermion loops are
computed. To keep statistical errors small, it is essential to optimize the
computation of these diagrams by choosing that combination of techniques most
appropriate for each type of diagram from the correlation matrix of
interpolating operators. We illustrate, how this can be done, by discussing
certain diagrams in detail. We also present preliminary results corresponding
to a submatrix computed with 2+1 flavors of clover fermions.Comment: 13 pages, 9 figures, talks given at the 32nd International Symposium
on Lattice Field Theory (Lattice 2014), 23-28 June 2014, Columbia University,
New York, NY, US
Lattice investigation of the tetraquark candidates a0(980) and kappa
It is a long discussed issue whether light scalar mesons have sizeable four-quark components. We present an exploratory study of this question using Nf = 2+1+1 twisted mass lattice QCD. A mixed action approach ignoring disconnected contributions is used to calculate correlatormatrices consisting of mesonic molecule, diquark-antidiquark and two-meson interpolating operators with quantum numbers of the scalar mesons a0(980) (1(0++)) and k (1/2(0+)). The correlation matrices are analyzed by solving the generalized eigenvalue problem. The theoretically expected free two-particle scattering states are identified, while no additional low lying states are observed. We do not observe indications for bound four-quark states in the channels investigated
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