Proton-proton, pion-proton and pion-pion diffractive collisions at ultra-high energies

The LHC energies are those at which the asymptotic regime in hadron-hadron diffractive collisions ($pp,\pi p,\pi\pi$) might be switched on. Based on results of the Dakhno-Nikonov eikonal model which is a generalization of the Good-Walker eikonal approach for a continuous set of channels, we present a picture for transformation of the constituent quark mode to the black disk one. In the black disk mode ($\sqrt s \geq 10$ TeV) we have a growth of the logarithm squared type for total and elastic cross sections, $\sigma_{tot}\sim\ln^2s$ and $\sigma_{el}\sim\ln^2s$, and $(\tau={\bf q}_\perp^2\sigma_{tot})$-scaling for diffractive scattering and diffractive dissociation of hadrons. The diffractive dissociation cross section grows as $\sigma_{D}\sim\ln{s}$, $\sigma_{DD}\sim\ln{s}$, and their relative contribution tends to zero: $\sigma_{D}/\sigma_{tot}\to 0$, $\sigma_{DD}/\sigma_{tot}\to 0$. Asymptotic characteristics of diffractive and total cross sections are universal, and this results in the asymptotical equality of cross sections for all types of hadrons (the Gribov's universality). The energy scale for switching on the asymptotic mode is estimated for different processes.Comment: 14 pages. arXiv admin note: text overlap with arXiv:1310.283

Dynamical interpretation of chemical freeze-out in heavy ion collisions

It is demonstrated that there exists a direct correlation between chemical freeze-out point and the softest point of the equation of state where the pressure divided by the energy density, $p(\epsilon)/\epsilon$, has a minimum. A dynamical model is given as an example where the passage of the softest point coincides with the condition for chemical freeze-out, namely an average energy per hadron $\approx$ 1 GeV. The sensitivity of the result to the equation of state used is discussed.Comment: 10 pages, 2 figure

Resonantly enhanced nonlinear optics in semiconductor quantum wells: An application to sensitive infrared detection

A novel class of coherent nonlinear optical phenomena, involving induced transparency in quantum wells, is considered in the context of a particular application to sensitive long-wavelength infrared detection. It is shown that the strongest decoherence mechanisms can be suppressed or mitigated, resulting in substantial enhancement of nonlinear optical effects in semiconductor quantum wells.Comment: 4 pages, 3 figures, replaced with revised versio

Dual Interpretations of Pion Clouds at RHIC

A gauge theory of pions interacting with rho-mesons at elevated temperatures is used to calculate the pressure in a hot pion gas. No reference is made to the pion's status as a QCD Goldstone boson. The role of the pion is merely that of a carrier of an SU(2) symmetry, gauged to create a vector-meson interaction, the rho playing the role of the interacting vector particle. The results are in rough agreement with much more elaborate calculations, both of the purely hadronic variety, and those that invoke quark-gluon degrees of freedom. The quark-gluon and purely hadronic calculations seemingly lead to very similar predictions which are in accord with receent data from RHIC. The results motivate the question as to whether the two descriptions are dual to each other in the sense of being alternate models, each sufficient to explain the observed data.Comment: 11 pages, 4 figures (2 eps files, 1 ps file) + a figure that uses metafont package feynmf, also forwarded. Open with "latex feynmf.ins". See http://www.ctan.org/tex-archive/help/Catalogue/entries/feynmf.html 9/6/06 replaced figure 2 with scaled version of sam