相关论文: Scalar mesons and tetraquarks from twisted mass la…
We study the light scalar mesons a_0(980) and kappa using N_f = 2+1+1 flavor lattice QCD. In order to probe the internal structure of these scalar mesons, and in particular to identify, whether a sizeable tetraquark component is present, we…
It is a long discussed issue whether light scalar mesons have sizeable four-quark components. We present an exploratory study of this question using N_f=2+1+1 twisted mass lattice QCD. A mixed action approach ignoring disconnected…
We study the possibility that the light scalar mesons are (qbar qbar q q) states rather than (qbar q). We perform a lattice QCD calculation of pseudoscalar meson scattering amplitudes, ignoring quark loops and quark annihilation, and find…
We study the a_0 and K_0^* light scalar mesons in 2+1 flavor full QCD. Particular attention is paid to fitting excited states, with an eye toward determining whether scattering states are revealed. An ultimate goal will be to see how…
We review the status of an ongoing long-term lattice investigation of the spectrum and structure of tetraquark candidates. We focus on the light scalar meson $a_0(980)$. First steps regarding the study of a possibly existing $c c \bar{c}…
I describe some insight obtained from a lattice calculation on the possibility that the light scalar mesons are \qbar^2 q^2 states rather than \qbar q. First I review some general features of \qbar^2 q^2 states in QCD inspired quark models.…
Searches for tetraquarks and mesonic molecules in lattice QCD are briefly reviewed. In the light quark sector the most serious candidates are the lightest scalar resonances sigma, kappa, a0 and f0. In the hidden-charm sector I discuss…
We study the lowest-lying scalar mesons in the QCD sum rule by considering them as tetraquark states. We find that there are five independent currents for each state with a certain flavor structure. By forming linear combinations, we find…
We investigate the quark content of the scalar meson $a_0(980)$ using lattice QCD. To this end we consider correlation functions of six different two- and four-quark interpolating fields. We evaluate all diagrams, including diagrams, where…
Lattice QCD allows us to probe the low-lying hadron spectrum in finite-volume using a basis of single- and multi-hadron interpolating operators. Here we examine the effect of including tetraquark operators on the spectrum in the scalar…
Despite the apparent simplicity of meson spectroscopy, light scalar mesons cannot be accommodated in the usual $q\bar q$ structure. We study the description of the scalar mesons below 2 GeV in terms of the mixing of a chiral nonet of…
Lattice QCD with $N_f=2$ flavours of sea quark is used to explore the spectrum and decay of scalar mesons. We are able to determine the $b_1$ - $a_0$ mass difference and this leads to the conclusion that the lightest non-singlet scalar…
Scalar tetraquark states are studied within the diquark-antidiquark picture in a non-relativistic approach. We consider two types of confining potentials, a quadratic and a linear one, to which we also add spin-spin, isospin-isospin, and…
The observed mass pattern of scalar resonances below 1 GeV gives preference to the tetraquark assignment over the conventional $\bar qq$ assignment for these states. We present a search for tetraquarks with isospins 0, 1/2, 1 in lattice…
Using effective field theory methods, we discuss the extraction of the mass and width of the scalar mesons f0(980) and a0(980) from the finite-volume spectrum in lattice QCD. In particular, it is argued that the nature of these states can…
We discuss technical aspects and first results of a lattice QCD study of the $a_0(980)$ state. We employ various interpolating operators of quark-antiquark, mesonic molecule, diquark-antidiquark and two-meson type. Both connected and…
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…
We present results of a lattice calculation of tetraquark states with quark contents $q_1q_2\bar{Q}\bar{Q}, \, q_1,q_2 \subset u,d,s,c$ and $Q \equiv b,c$ in both spin zero ($J=0$) and spin one ($J=1$) sectors. These calculations are…
We carry out an exploratory study of the isospin one a0(980) and the isospin one-half kappa scalar mesons using Nf=2+1+1 Wilson twisted mass fermions at one lattice spacing. The valence strange quark is included as an Osterwalder-Seiler…
The role of tetraquark operators in studying the isodoublet strange $\kappa$ and isovector nonstrange $a_0(980)$ scalar mesons in lattice QCD is examined using an ensemble with $m_\pi\approx230$ MeV and spatial extent $L$ such that $m_\pi…