3,388 research outputs found
Strong decays of and
With the identification of () as the (,
) doublet in the heavy quark effective field theory, we derive the light
cone QCD sum rule for the coupling of eta meson with and
. Through mixing we calculate their pionic
decay widths, which are consistent with the experimental values (or upper
limits). Combining the radiative decay widths derived by Colangelo, Fazio and
Ozpineci in the same framework, we conclude that the decay patterns of
strongly support their interpretation as ordinary mesons.Comment: Comments and suggestions welcome
The masses and axial currents of the doubly charmed baryons
The chiral dynamics of the doubly heavy baryons is solely governed by the
light quark. In this work, We have derived the chiral corrections to the mass
of the doubly heavy baryons up to NLO. The mass splitting of and
at the NLO depends on one unknown low energy constant .
With the experimental mass of as the input, we estimate the
mass of to be around 3.678 GeV. Moreover, we have also performed
a systematical analysis of the chiral corrections to the axial currents and
axial charges of the doubly heavy baryons. The chiral structure and analytical
expressions will be very useful to the chiral extrapolations of the future
lattice QCD simulations of the doubly heavy baryons.Comment: 10 pages, 2 tables, 3 figure. Accepted by Phys. Rev.
The long-lasting optical afterglow plateau of short burst GRB 130912A
The short burst GRB 130912A was detected by Swift, Fermi satellites and
several ground-based optical telescopes. Its X-ray light curve decayed with
time normally. The optical emission, however, displayed a long term plateau,
which is the longest one in current short GRB observations. In this work we
examine the physical origin of the X-ray and optical emission of this peculiar
event. We find that the canonical forward shock afterglow emission model can
account for the X-ray and optical data self-consistently and the energy
injection model that has been widely adopted to interpret the
shallowly-decaying afterglow emission is not needed. We also find that the
burst was born in a very-low density interstellar medium, consistent with the
compact object merger model. Significant fractions of the energy of the forward
shock have been given to accelerate the non-thermal electrons and amplify the
magnetic fields (i.e., and , respectively), which are much larger than those inferred in most short
burst afterglow modeling and can explain why the long-lasting optical afterglow
plateau is rare in short GRBs.Comment: 5 pages, 2 figure
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