0000000000281297
AUTHOR
K. Kajantie
Mass spectrum and thermodynamics of quasi-conformal gauge theories from gauge/gravity duality
We use gauge/gravity duality to study simultaneously the mass spectrum and the thermodynamics of a generic quasi-conformal gauge theory, specified by its beta function. The beta function of a quasi-conformal theory almost vanishes, and the coupling is almost constant between two widely separated energy scales. Depending on whether the gravity dual has a black hole or not, the mass spectrum is either a spectrum of quasinormal oscillations or a normal T=0 mass spectrum. The mass spectrum is quantitatively correlated with the thermal properties of the system. As the theory approaches conformality, the masses have to vanish. We show that in this limit, the masses calculated via gauge/gravity du…
Rapidity dependence of particle production in ultrarelativistic nuclear collisions
We compute the rapidity dependence of particle and transverse energy production in ultrarelativistic heavy ion collisions at various beam energies and atomic numbers using the perturbative QCD + saturation model. The distribution is a broad gaussian near $y=0$ but the rapid increase of particle production with the beam energy will via energy conservation strongly constrain the rapidity distribution at large $y$.
Hydrodynamics of nuclear collisions with initial conditions from perturbative QCD
We compute the longitudinal hydrodynamic flow in ultrarelativistic heavy ion collisions at $\sqrt{s}$ = 5500 GeV by using boost non-invariant initial conditions following from perturbative QCD. The transfer of entropy and energy from the central region to larger rapidities caused by boost non-invariance is determined and the associated decrease in the lifetime of the system is estimated.
Production of thermal dileptons in high energy nucleus-nucleus collisions
A method for including realistic nuclear geometry and impact parameter effects in computations of production rates of thermal dileptons of mass in the 1.5 to 3 GeV range andy≈0 in nucleus nucleus collisions at $$\sqrt s = 20 - 200$$ GeV is given. A comparison with the Drell-Yan rate indicates that for large nuclei and energies thermal production gives a sizable contribution even atM=M Jψ and thus may contribute significantly toJ/ψ suppression as background enchancement.
Erratum to: A model for holographic QCD in the Veneziano limit at finite temperature and density
Erratum to: JHEP04(2014)124
Heavy ion collision multiplicities and gluon distribution functions
Atomic number ($A$) and energy ($\roots$) scaling exponents of multiplicity and transverse energy in heavy ion collisions are analytically derived in the perturbative QCD + saturation model. The exponents depend on the small-$x$ behaviour of gluon distribution functions at an $x$-dependent scale. The relation between initial state and final state saturation is also discussed.
Centrality dependence of multiplicities in ultrarelativistic nuclear collisions
We compute the centrality dependence of multiplicities of particles produced in ultrarelativistic nuclear collisions at various energies and atomic numbers. The computation is carried out in perturbative QCD with saturated densities of produced gluons and by including effects of nuclear geometry. Numbers are given for Au+Au collisions at RHIC energies.
Where Do Diffractive Nucleons Go?
Nucleon and pion-nucleon distributions from the diffractive component in pp collisions are analysed. Diffractive events are assumed to come from a mechanism pp → N*p, in which a proton is diffractively excited to a nova N*. The decay properties of N* are determined by assuming that a Pomeron-proton collision behaves as a proton-proton collision. Correlations within the diffractive component are computed and seen to be numerically small. Even interference with the pionization component does not reproduce the observed pattern of pion (in the plateau)-proton (in the fragmentation region) correlations. This may imply the existence of long-range correlations within the pionization component.
Long-range correlations in the pionization component
Recen t ly I S R measuremen t s (1,2) of corre la t ions be tween a p ion in t he p la teau (lY=I 0 . 2 ) have been carr ied out . A typ ica l resul t is a corre la t ion func t ion which (if one holds y= fixed and the t ransverse m o m e n t u m of t he p ro ton < 1 GeV/c) has a pos i t ive va lue a t smal ler x, a zero at about x = 0.5, a rough ly cons tan t nega t ive va lue for 0.5 < x < 0.8 and approaches a large nega t ive va lue for x close to 1 (see below). In the fol lowing we shall quan t i t a t i ve ly expla in this s t ruc tu re in t e rms of a mode l which essent ial ly amoun t s to pu t t i ng f ini te-energy correct ions to a mul t ipe r iphe ra l c luster model . I n t he t…