279 research outputs found
Evidence for low freeze-out temperature and large transverse flow in central collisions of Pb + Pb at 158 AGeV
Utilizing a hydrodynamical model for the freeze-out stage in heavy-ion
reactions, we extract from resolved transverse hadron spectra at midrapidity an
inverse slope parameter (temperature) 120 MeV and an averaged
transverse flow velocity 0.43 c in central collisions
of Pb + Pb at 158 AGeV.Comment: 6 LaTeX pages 5 eps figure
Pion Exchange Effects in Elastic Backward Proton-Deuteron Scattering
The elastic backward proton-deuteron scattering is analyzed within a
covariant approach based on the Bethe-Salpeter equation with realistic
meson-exchange interaction. Contributions of the one-nucleon and one-pion
exchange mechanisms to the cross section and polarization observables are
investigated in explicit form. Results of numerical calculations for the cross
section, tensor analyzing power and spin transfers are presented. The one-pion
exchange contribution is essential for describing the spin averaged cross
section, while in polarization observables it is found to be less important.Comment: 19 LaTeX pages, including 5 eps figure
Baryon chiral perturbation theory transferred to hole-doped antiferromagnets on the honeycomb lattice
A systematic low-energy effective field theory for hole-doped
antiferromagnets on the honeycomb lattice is constructed. The formalism is then
used to investigate spiral phases in the staggered magnetization as well as the
formation of two-hole bound states.Comment: Talk delivered by C.P. Hofmann at the XIII Mexican Workshop on
Particles and Fields, October 19-26, 2011, Leon, Guanajuato, Mexico; 15
pages, 7 figure
Field induced phase transition in the few photon regime
Some features of the field induced phase transition accompanied by the vacuum
creation of an electron-positron plasma (EPP) in strong time-dependent electric
fields have been discussed in the work [1] in the domain of the tunneling
mechanism (, where is the characteristic frequency of
the external field and is the electron mass). In the present contribution
the features of the this process will be considered in the few photon domain
where . We observe a narrowing of the transient domain of the
fast oscillations and, mainly, a considerable growth of the effectiveness of
the EPP production. Under these circumstances, we see an increase of the
effectiveness of the EPP creation in the particular case of a bifrequent
excitation, where both mechanisms (tunneling and few photon) act simultaneously
[2,3].Comment: 6 pages, 4 figures, contribution to the Proceedings of the XXIII
International Baldin Seminar on "High Energy Physics Problems", Dubna,
Russia, September 19-24, 201
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