23 research outputs found
Delayed clusters accompanying nonmesonic weak decay of the -hypernuclei: a clue to nonleptonic processes
The nonmesonic decay of -hypernuclei provides access to the
nonleptonic weak decay process , which is achievable only
through the observation of hypernuclear ground-state decays. We continue the
discussion of some specific cases which make it possible to detect a few
exclusive transitions, namely, the stripping of nucleon from the ground state
results in a resonance state decaying via emission of two clusters. Delayed
clusters accompanying weak decay of light hypernuclei give a unique information
on spin dependence of the weak decay matrix elements.Comment: Presented at International Bogolyubov Conference "Problems of
Theoretical and Mathematical Physics" (dedicated to the 100th anniversary of
the birth of N.N.~Bogolyubov) Dubna, Russia, August 21 - 27, 200
Fast hadron freeze-out generator, part II: noncentral collisions
The fast Monte Carlo procedure of hadron generation developed in our previous
work is extended to describe noncentral collisions of nuclei. We consider
different possibilities to introduce appropriate asymmetry of the freeze-out
hyper-surface and flow velocity profile. For comparison with other models and
experimental data we demonstrate the results based on the standard
parametrizations of the hadron freeze-out hyper-surface and flow velocity
profile assuming either a common chemical and thermal freeze-out or the
chemically frozen evolution from chemical to thermal freeze-out. The C++
generator code is written under the ROOT framework and is available for public
use at http://uhkm.jinr.ru/Comment: 27 pages including 7 figures as EPS-files; prepared using LaTeX
package for publication in Physical Review
Centrality dependence of the expansion dynamics in Pb-Pb collisions at 158 A GeV/c
Two-particle correlation functions of negatively charged hadrons from Pb-Pb
collisions at 158 GeV/c per nucleon have been measured by the WA97 experiment
at the CERN SPS. A Coulomb correction procedure that assumes an expanding
source has been implemented. Within the framework of an expanding thermalized
source model the size and dynamical state of the collision fireball at
freeze-out have been reconstructed as a function of the centrality of the
collision. Less central collisions exhibit a different dynamics than central
ones: both transverse and longitudinal expansion velocities are slower, the
expansion duration is shorter and the system freezes out showing smaller
dimensions and higher temperature.Comment: 22 pages, 11 figures, Te
Transverse Momentum and Rapidity Dependence of HBT Correlations in Au+Au Collisions at sqrt(s_NN) = 62.4 and 200 GeV
Two-particle correlations of identical charged pion pairs from Au+Au
collisions at sqrt(s_NN) = 62.4 and 200 GeV were measured by the PHOBOS
experiment at RHIC. Data for the 15% most central events were analyzed with
Bertsch-Pratt and Yano-Koonin-Podgoretskii parameterizations using pairs with
rapidities of 0.4 < y_{\pi\pi} < 1.3 and transverse momenta 0.1 < k_T < 1.4
GeV/c. The Bertsch-Pratt radii R_o and R_l decrease as a function of pair
transverse momentum, while R_s is consistent with a weaker dependence. R_o and
R_s are independent of collision energy, while R_l shows a slight increase. The
source rapidity y_{ykp} scales roughly with the pair rapidity y_{\pi\pi},
indicating strong dynamical correlations.Comment: 5 pages, 4 figures, 2 tables, submitted to Phys. Rev.
Rapidity and k_T dependence of HBT correlations in Au+Au collisions at 200 GeV with PHOBOS
Two-particle correlations of identical charged pion pairs from Au+Au
collisions at sqrt(s_NN) = 200 GeV were measured by the PHOBOS experiment at
RHIC. Data for the most central (0--15%) events were analyzed with
Bertsch-Pratt (BP) and Yano-Koonin-Podgoretskii (YKP) parameterizations using
pairs with rapidities of 0.4 < y < 1.3 and transverse momenta 0.1 < k_T < 1.4
GeV/c. The Bertsch-Pratt radii decrease as a function of pair transverse
momentum. The pair rapidity Y_pipi roughly scales with the source rapidity
Y_YKP, indicating strong dynamical correlations.Comment: 5 pages, 2 figures. To appear in the proceedings of Seventeenth
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(Quark Matter 2004), Oakland, California from January 11-17, 2004. Submitted
to Journal of Physics G: Nuclear and Particle Physic