8,983 research outputs found
Strangeness Production in Light and Intermediate size Nucleus-Nucleus Collisions
Within the statistical model, the net strangeness conservation and incomplete
total strangeness equilibration lead to the suppression of strange particle
multiplicities. Furthermore, suppression effects appear to be stronger in small
systems. By treating the production of strangeness within the canonical
ensemble formulation we developed a simple model which allows to predict the
excitation function of ratio in nucleus-nucleus collisions. In
doing so we assumed that different values of , measured in p+p and
Pb+Pb interactions at the same collision energy per nucleon, are driven by the
finite size effects only. These predictions may serve as a baseline for
experimental results from NA61/SHINE at the CERN SPS and the future CBM
experiment at FAIR
Lifetime of molecule-atom mixtures near a Feshbach resonance in 40K
We report a dramatic magnetic field dependence in the lifetime of trapped,
ultracold diatomic molecules created through an s-wave Feshbach resonance in
40K. The molecule lifetime increases from less than 1 ms away from the Feshbach
resonance to greater than 100 ms near resonance. We also have measured the
trapped atom lifetime as a function of magnetic field near the Feshbach
resonance; we find that the atom loss is more pronounced on the side of the
resonance containing the molecular bound state
Phase Transition in Hot Pion Matter
The equation of state for the pion gas is analyzed within the third virial
approximation. The second virial coefficient is found from the pion-pion-
scattering data, while the third one is considered as a free parameter. The
proposed model leads to a first-order phase transition from the pion gas to a
more dense phase at the temperature T_pt < 136 MeV. Due to relatively low
temperature this phase transition cannot be related to the deconfinement. This
suggests that a new phase of hadron matter - 'hot pion liquid' - may exist.Comment: 11 pages, Latex, 4 PS-figures. V2: A few misprints are corrected.
Acknowledgments are adde
Creation of macroscopic superpositions of flow states with Bose-Einstein condensates
We present a straightforward scheme for creating macroscopic superpositions
of different superfluid flow states of Bose-Einstein condensates trapped in
optical lattices. This scheme has the great advantage that all the techniques
required are achievable with current experiments. Furthermore, the relative
difficulty of creating cats scales favorably with the size of the cat. This
means that this scheme may be well-suited to creating superpositions involving
large numbers of particles. Such states may have interesting technological
applications such as making quantum-limited measurements of angular momentum.Comment: 9 pages, 7 figure
Wavelets and Quantum Algebras
Wavelets, known to be useful in non-linear multi-scale processes and in
multi-resolution analysis, are shown to have a q-deformed algebraic structure.
The translation and dilation operators of the theory associate with any scaling
equation a non-linear, two parameter algebra. This structure can be mapped onto
the quantum group in one limit, and approaches a Fourier series
generating algebra, in another limit. A duality between any scaling function
and its corresponding non-linear algebra is obtained. Examples for the Haar and
B-wavelets are worked out in detail.Comment: 27 pages Latex, 3 figure p
J/psi Suppression and Enhancement in Au+Au Collisions at the BNL RHIC
We consider the production of the J/psi mesons in heavy ion collisions at
RHIC energies in the statistical coalescence model with an exact (canonical
ensemble) charm conservation. The c\bar{c} quark pairs are assumed to be
created in the primary hard parton collisions, but the formation of the open
and hidden charm particles takes place at the hadronization stage and follows
the prescription of statistical mechanics. The dependence of the J/psi
production on both the number of nucleon participants and the collision energy
is studied. The model predicts the J/psi suppression for low energies, whereas
at the highest RHIC energy the model reveals the J/psi enhancement.Comment: 14 pages, REVTeX, 3 PS-figure
Dynamics of matter solitons in weakly modulated optical lattices
It is shown that matter solitons can be effectively managed by means of
smooth variations of parameters of optical lattices in which the condensate is
loaded. The phenomenon is based on the effect of lattice modulations on the
carrier wave transporting the soliton and that is why is well understood in
terms of the effective mass approach, where a particular spatial configuration
of the band structure is of primary importance. Linear, parabolic, and
spatially localized modulations are considered as the case examples. It is
shown that these defects can originate accelerating and oscillating motion of
matter solitons as well as simulate soliton interaction with attractive and
repulsive defects.Comment: 6 pages, 7 figures (text with major revision
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