48,138 research outputs found
Phase diagram of a Bose gas near a wide Feshbach resonance
In this paper, we study the phase diagram of a homogeneous Bose gas with a
repulsive interaction near a wide Feshbach resonance at zero temperature. The
Bose-Einstein-condensation (BEC) state of atoms is a metastable state. When the
scattering length exceeds a critical value depending on the atom density
, , the molecular excitation energy is imaginary and the atomic
BEC state is dynamically unstable against molecule formation. The BEC state of
diatomic molecules has lower energy, where the atomic excitation is gapped and
the molecular excitation is gapless. However when the scattering length is
above another critical value, , the molecular BEC state becomes a
unstable coherent mixture of atoms and molecules. In both BEC states, the
binding energy of diatomic molecules is reduced due to the many-body effect.Comment: 5 pages, 4 figure
Possible Implication of a Single Nonextensive Distribution for Hadron Production in High-Energy Collisions
Multiparticle production processes in collisions at the central rapidity
region are usually considered to be divided into independent "soft" and "hard"
components. The first is described by exponential (thermal-like) transverse
momentum spectra in the low- region with a scale parameter associated
with the temperature of the hadronizing system. The second is governed by a
power-like distributions of transverse momenta with power index at
high- associated with the hard scattering between partons. We show that
the hard-scattering integral can be approximated as a nonextensive distribution
of a quasi-power-law containing a scale parameter and a power index , where is the nonextensivity parameter. We demonstrate that the whole
region of transverse momenta presently measurable at LHC experiments at central
rapidity (in which the observed cross sections varies by orders of
magnitude down to the low region) can be adequately described by a single
nonextensive distribution. These results suggest the dominance of the
hard-scattering hadron-production process and the approximate validity of a
"no-hair" statistical-mechanical description of the spectra for the whole
region at central rapidity for collisions at high-energies.Comment: 10 pages, 3 figures; presented by G.Wilk at the XLIV International
Symposium on Multiparticle Dynamics; 8 - 12 September 2014 - Bologna, ITAL
- …