5,801 research outputs found
Coherent and Non-Coherent Double Diffractive Production of - pairs in Collisions of Heavy Ions at High Energies
The double coherent and non-coherent diffractive production of heavy quark -
antiquark pairs () in heavy ion scattering at high energies (LHC) is
considered. The total and differential cross sections of these processes with
the formation of and pairs in , and
collisions are evaluated. The contribution of the considered mechanisms is a
few per cent of the number of heavy quark - antiquark pairs obtained in the
processes of hard (QCD) scattering, and it will be taken into account in the
registration of , quarks or, for instance, in the study of the heavy
quarkonia suppression effects in Quark - Gluon Plasma, in the search for
intermediate mass Higgs bosons and so on. It is shown that the cross section of
the coherent scattering process is great enough. This makes it suitable for
studying collective effects in nuclear interactions at high energies. An
example of such effects is given: large values of the invariant mass of a pair, M_{Q \bar{Q}} \gsim 100 GeV, in association with a large
rapidity gap between diffractive jets .Comment: 22 pages, 5(.eps) figures, 3 tables, LaTe
Frustrations on decorated triangular lattice in Ising model
We study the frustration properties of the Ising model on a decorated
triangular lattice with an arbitrary number of decorating spins on all lattice
bonds in the framework of an exact analytical approach based on the
Kramers--Wannier transfer matrix method. Expressions for the entropy, heat
capacity, and spontaneous magnetization of the lattice are obtained, including
the residual (zero-temperature) entropy and residual (zero-temperature)
spontaneous magnetization of the system. The existence of magnetic frustrations
in such a model and their influence on the behavior of the thermodynamic
functions of the system are shown. The new and most important result of our
study is related to the description of the possible coexistence of frustrations
and long-range magnetic order in partially ordered spin systems
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