11,724 research outputs found
Phi meson mass and decay width in nuclear matter
The meson spectrum, which in vacuum is dominated by its coupling to
the system, is modified in nuclear matter. Following a model based
on chiral SU(3) dynamics we calculate the meson selfenergy in nuclear
matter considering the and in-medium properties. For the latter
we use the results of previous calculations which account for and wave
kaon-nucleon interactions based on the lowest order meson-baryon chiral
effective Lagrangian, and this leads to a dressing of the kaon propagators in
the medium. In addition, a set of vertex corrections is evaluated to fulfill
gauge invariance, which involves contact couplings of the meson to
wave and wave kaon-baryon vertices. Within this scheme the mass shift
and decay width of the meson in nuclear matter are studied.Comment: 19 pages, 10 figures in EPS format, revtex4; One section modified,
some references update
Shedding light on the anomalies with a dark sector
The LHCb collaboration has recently reported on some anomalies in
transitions. In addition to discrepancies with the Standard Model (SM)
predictions in some angular observables and branching ratios, an intriguing
hint for lepton universality violation was found. Here we propose a simple
model that extends the SM with a dark sector charged under an additional
gauge symmetry. The spontaneous breaking of this symmetry gives rise to a
massive boson, which communicates the SM particles with a valid dark
matter candidate, while solving the anomalies with contributions to
the relevant observables.Comment: 9 pages, 4 figures. Few typos corrected, references adde
Bound states of in nuclei
We study the binding energy and the width of the in nuclei,
associated to the and components. The first one leads to
negligible contributions while the second one leads to a sizeable attraction,
enough to bind the in nuclei. Pauli blocking and binding effects on
the decay reduce considerably the decay width in nuclei and
medium effects associated to the component also lead to a very small
width, as a consequence of which one finds separation between the bound levels
considerably larger than the width of the states.Comment: Presentation in the 10th International Baryon Conference BARYON0
Dynamically Generated Open and Hidden Charm Meson Systems
We will study open and hidden charm scalar meson resonances within two
different models. The first one is a direct application of a chiral Lagrangian
already used to study flavor symmetry breaking in Skyrme models. In another
approach to the problem a SU(4) symmetric Lagrangian is built and the symmetry
is broken down to SU(3) by identifying currents where heavy mesons are
exchanged and suppressing those. Unitarization in couple channels leads to
dynamical generation of resonances in both models, in particular a new hidden
charm resonance with mass 3.7 GeV is predicted. The small differences between
these models and with previous works will be discussed.Comment: 32 pages, 10 figures. Added extra calculations with explicit symmetry
breaking terms in chiral Lagrangian
eta - eta' - glueball mixing
We have revisited glueball mixing with the pseudoscalar mesons in the MIT bag
model scheme. The calculation has been performed in the spherical cavity
approximation to the bag using two different fermion propagators, the cavity
and the free propagators. We obtain a very small probability of mixing for the
eta at the level of $0.04-0.1% and a bigger for the eta' at the level of 4-12%.
Our results differ from previous calculations in the same scheme but seem to
agree with the experimental analysis. We discuss the origin of our difference
which stems from the treatment of our time integrations.Comment: 21 pages, 7 figure
Formation of mesic nuclei
We study the structure and formation of the mesic nuclei to
investigate the in-medium modification of the -meson spectral function at
finite density. We consider (), () and ()
reactions to produce a -meson inside the nucleus and evaluate the effects
of its medium modifications to the reaction cross sections. We also estimate
the consequences of the uncertainties of the selfenergy in medium to
the -nucleus interaction. We find that it may be possible to see a peak
structure in the reaction spectra for the strong attractive potential cases. On
the other hand, for strong absorptive interaction cases with relatively weak
attractions, it is very difficult to observe clear peaks and we may need to
know the spectrum shape in a wide energy region to deduce the properties of
.Comment: 11 pages, 8 figure
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