Hadronic correlations above the chiral/deconfinement transition

The statistical bootstrap model is critically revised in order to include a medium-dependent resonance width in it. We show that a thermodynamic model with a vanishing width below the Hagedorn temperature T_H and a Hagedorn spectrum-like width above T_H may not only eliminate the divergence of the thermodynamic functions above T_H, but also gives a satisfactory description the lattice quantum chromodynamics (QCD) data on the energy density above the chiral/deconfinement transition as the main result of this contribution. This model allows to explain the absence of heavy resonance contributions in the fit of the experimentally measured particle ratios at SPS and RHIC energies.Comment: 9 pages, 2 figures, contribution to proceedings of NAPP 2003, Dubrovnik, Croatia, 26-31 May, 200

Mott effect at the chiral phase transition and anomalous J/Psi suppression

We investigate the in-medium modification of the charmonium break-up processes due to the Mott effect for light (pi) and open-charm (D, D*) mesons at the chiral/deconfinement phase transition. A model calculation for the process J/Psi + pi -> D + \bar D* + h.c. is presented which demonstrates that the Mott effect for the D-mesons leads to a threshold effect in the thermal averaged break-up cross section. This effect is suggested as an explanation of the phenomenon of anomalous J/Psi suppression in the CERN NA50 experiment.Comment: 9 pages, 3 figures; final version to appear in Phys. Lett.

Implications from GW170817 and I-Love-Q relations for relativistic hybrid stars

Gravitational wave observations of GW170817 placed bounds on the tidal deformabilities of compact stars allowing one to probe equations of state for matter at supranuclear densities. Here we design new parametrizations for hybrid hadron-quark equations of state, that give rise to low-mass twin stars, and test them against GW170817. We find that GW170817 is consistent with the coalescence of a binary hybrid star--neutron star. We also test and find that the I-Love-Q relations for hybrid stars in the third family agree with those for purely hadronic and quark stars within $\sim 3\%$ for both slowly and rapidly rotating configurations, implying that these relations can be used to perform equation-of-state independent tests of general relativity and to break degeneracies in gravitational waveforms for hybrid stars in the third family as well.Comment: 8 pages, 4 figures, 2 tables; matches published version, updated fig.

Conformal relativity versus Brans-Dicke and superstring theories

Conformal relativity theory which is also known as Hoyle-Narlikar theory has recently been given some new interest. It is an extended relativity theory which is invariant with respect to conformal transformations of the metric. In this paper we show how conformal relativity is related to the Brans-Dicke theory and to the low-energy-effective superstring theory. We show that conformal relativity action is equaivalent to a transformed Brans-Dicke action for Brans-Dicke parameter $\omega = -3/2$ in contrast to a reduced (graviton-dilaton) low-energy-effective superstring action which corresponds to a Brans-Dicke action with Brans-Dicke parameter $\omega = -1$. In fact, Brans-Dicke parameter $\omega =-3/2$ gives a border between a standard scalar field evolution and a ghost. We also present basic cosmological solutions of conformal relativity in both Einstein and string frames. The Eintein limit for flat conformal cosmology solutions is unique and it is flat Minkowski space. This requires the scalar field/mass evolution instead of the scale factor evolution in order to explain cosmological redshift. It is interesting that like in ekpyrotic/cyclic models, a possible transition through a singularity in conformal cosmology in the string frame takes place in the weak coupling regime.Comment: REVTEX4, 12 pages, an improved version, references adde

Hadronske korelacije iznad prijelaza kiralnost – odsužnjivanje

The statistical bootstrap model is critically revised in order to include a medium-dependent resonance width in it. We show that a thermodynamic model with a vanishing width below the Hagedorn temperature TH and a Hagedorn spectrum-like width above TH may not only eliminate the divergence of the thermodynamic functions above TH, but also gives a satisfactory description of the lattice quantum chromodynamics data on the energy density above the chiral/deconfinement transition as the main result of this contribution. This model allows us to explain the absence of heavy resonance contributions in the fit of the experimentally measured particle ratios at SPS and RHIC energies.Kritički prerađujemo statistički model samopodizanja kako bi u njega uključili širine rezonancija ovisne o sredini. Pokazujemo da termodinamički model s iščezavajućom širinom ispod Hagedornove temperature TH, i sa spektralnom širinom poput Hagedornovove iznad TH, može ukloniti divergenciju termodinamičkih funkcija iznad TH, ali on također daje dobar opis podataka kvantne kromodinamike na rešetci za gustoću energije iznad prijelaza kiralnost – odsužnjivanje, što je glavni doprinos ovog rada. Taj model objašnjava nepojavljivanje teških rezonancija u mjerenjima eksperimentalnih čestičnih omjera na energijama SPS i RHIC

Observable effects caused by vacuum pair creation in the field of high-power optical lasers

We consider the possibility of an experimental proof of vacuum e+e- pair creation in the focus of two counter-propagating optical laser beams with an intensity of the order of 10^20 - 10^22 W/cm^2. Our approach is based on the collisionless kinetic equation for the distribution function of the e+e- pairs with the source term for particle production. As a possible experimental signal of vacuum pair production we consider the refraction of a high-frequency probe laser beam by the produced e+e- plasma to be observed by an interference filter. The generation of higher harmonics of the laser frequency in the self-consistent electric field is also investigated.Comment: 7 pages, 7 figures; typos corrected, Eq.(16) corrected, reference adde