248 research outputs found
Phase structures of the black D-D-brane system in various ensembles II: electrical and thermodynamic stability
By incorporating the electrical stability condition into the discussion, we
continue the study on the thermodynamic phase structures of the D-D
black brane in GG, GC, CG, CC ensembles defined in our previous paper
arXiv:1502.00261. We find that including the electrical stability conditions in
addition to the thermal stability conditions does not modify the phase
structure of the GG ensemble but puts more constraints on the parameter space
where black branes can stably exist in GC, CG, CC ensembles. In particular, the
van der Waals-like phase structure which was supposed to be present in these
ensembles when only thermal stability condition is considered would no longer
be visible, since the phase of the small black brane is unstable under
electrical fluctuations. However, the symmetry of the phase structure by
interchanging the two kinds of brane charges and potentials is still preserved,
which is argued to be the result of T-duality.Comment: 34 pages, 17 figure
Phase structures of the black D-D-brane system in various ensembles I: thermal stability
When the D-brane () with delocalized D charges is put into
equilibrium with a spherical thermal cavity, the two kinds of charges can be
put into canonical or grand canonical ensemble independently by setting
different conditions at the boundary. Using the thermal stability condition, we
discuss the phase structures of various ensembles of this system formed in this
way and find out the situations that the black brane could be the final stable
phase in these ensembles. In particular, van der Waals-like phase transitions
can happen when D0 and D4 charges are in different kinds of ensembles.
Furthermore, our results indicate that the D-branes and the delocalized
D-branes are equipotent.Comment: 45 pages, 16 figures, accepted by JHEP; A section added to briefly
discuss more general stability conditions, various typos correcte
Hadron loops effect on mass shifts of the charmed and charmed-strange spectra
The hadron loop effect is conjectured to be important in understanding
discrepancies between the observed states in experiments and the theoretical
expectations of non-relativistic potential model. We present that, in an easily
operable procedure, the hadron loop effect could shift the poles downwards to
reduce the differences and provide better descriptions of both the masses and
the total widths, at least, of the radial quantum number charmed and
charmed-strange states. The mixing phenomena could be naturally
explained due to their couplings with common channels. The newly observed
states are also addressed, but there are still some problems remaining unclear.Comment: 9 pages, 1 figur
Comprehending heavy charmonia and their decays by hadron loop effects
We present that including the hadron loop effects could help us to understand
the spectrum of the heavier charmonium-like states and their decays
simultaneously. The observed states could be represented by the poles on the
complex energy plane. By coupling to the opened thresholds, the pole positions
are shifted from the bare states predicted in the quenched potential model to
the complex energy plane. The pole masses are generally pulled down from the
bare masses and the open-charm decay widths are related to the imaginary parts
of the pole positions. Moreover, we also analyze the pole trajectory of the
state while the quark pair production rate from the vacuum
changes in its uncertainty region, which indicates that the enigmatic X(3872)
state may be regarded as a charmonium-dominated state
dressed by the hadron loops as the others.Comment: 7 pages, 1 figure, 2 table
- …