2,149 research outputs found
Narrow Tetraquarks at Large N
Following a recent suggestion by Weinberg, we use the large-N expansion in
QCD to discuss the decay amplitudes of tetraquarks into ordinary mesons as well
as their mixing properties. We find that the flavor structure of the tetraquark
is a crucial ingredient to determine both this mixing as well as the decays.
Although in some cases tetraquarks should be expected to be as narrow as
ordinary mesons, they may get to be even narrower, depending on this flavor
structure.Comment: 10 pages, 16 figure
Large-Nc QCD meets Regge theory: the example of spin-one two-point functions
We discuss the phenomenological implications of assuming a Veneziano-type
spectrum for the vector and axial-vector two-point functions in QCD at large
Nc. We also compare the phenomenological results with those of Lowest-Meson
Dominance, and find that they agree.Comment: 17 pages, 6 figure
Pion mass dependence of the HVP contribution to muon
One of the systematic errors in some of the current lattice computations of
the HVP contribution to the muon anomalous magnetic moment is that
associated with the extrapolation to the physical pion mass. We investigate
this extrapolation assuming lattice pion masses in the range of 220 to 440 MeV
with the help of two-loop chiral perturbation theory, and find that such an
extrapolation is unlikely to lead to control of this systematic error at the 1%
level. This remains true even if various proposed tricks to improve the chiral
extrapolation are taken into account.Comment: 8 pages, 3 figures; contribution to the proceedings of Lattice 201
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