7,284,368 research outputs found
A chiral model for bar{q}q and bar{q}bar{q}qq$ mesons
We point out that the spectrum of pseudoscalar and scalar mesons exhibits a
cuasi-degenerate chiral nonet in the energy region around 1.4 GeV whose scalar
component has a slightly inverted spectrum. Based on the empirical linear
rising of the mass of a hadron with the number of constituent quarks which
yields a mass around GeV for tetraquarks, we conjecture that this
cuasi-chiral nonet arises from the mixing of a chiral nonet composed of
tetraquarks with conventional bar{q}q states. We explore this possibility in
the framework of a chiral model assuming a tetraquark chiral nonet around 1.4
GeV with chiral symmetry realized directly. We stress that U_{A}(1)
transformations can distinguish bar{q}q from tetraquark states, although it
cannot distinguish specific dynamics in the later case. We find that the
measured spectrum is consistent with this picture. In general, pseudoscalar
states arise as mainly bar{q}q states but scalar states turn out to be strong
admixtures of bar{q}q and tetraquark states. We work out also the model
predictions for the most relevant couplings and calculate explicitly the strong
decays of the a_{0}(1450) and K_{0}^*(1430) mesons. From the comparison of some
of the predicted couplings with the experimental ones we conclude that
observable for the isovector and isospinor sectors are consistently described
within the model. The proper description of couplings in the isoscalar sectors
would require the introduction of glueball fields which is an important missing
piece in the present model.Comment: 20 pages, 3 figure
-potential: a numerical study
We report the results of recent lattice simulations aimed at computing the
and potential energies in the singlet and the octet (adjoint)
representation.Comment: 7 pages, 4 figures, poster presented at the 31st International
Symposium on Lattice Field Theory (Lattice 2013), 29 July - 3 August 2013,
Mainz, German
On a class of -Bernoulli, -Euler and -Genocchi polynomials
The main purpose of this paper is to introduce and investigate a class of
-Bernoulli, -Euler and -Genocchi polynomials. The -analogues of
well-known formulas are derived. The -analogue of the Srivastava--Pint\'er
addition theorem is obtained. Some new identities involving -polynomials are
proved
- …