Using combined data from the Relativistic Heavy Ion and Large Hadron Colliders, we constrain the shear and bulk viscosities of quark-gluon plasma (QGP) at temperatures of ∼ 150 – 350 MeV . We use ...Bayesian inference to translate experimental and theoretical uncertainties into probabilistic constraints for the viscosities. With Bayesian model averaging we propagate an estimate of the model uncertainty generated by the transition from hydrodynamics to hadron transport in the plasma's final evolution stage, providing the most reliable phenomenological constraints to date on the QGP viscosities.
We show that several effects considered nuclear effects are not nuclear in the sense that they do not only occur in nucleus–nucleus and hadron–nucleus collisions but, as well, they are present in ...hadron–hadron (proton–proton) collisions. The matter creation mechanism in
hh
,
hA
and
AA
collision is always the same. The
p
T
suppression of particles produced in large multiplicity events compared to low multiplicity events, the elliptic flow and the Cronin effect are predicted to occur in
pp
collisions at LHC energies as a consequence of the high density partonic medium obtained.
The collective interactions of many partons in the first stage of the collisions is the usual accepted explanation of the sizable elliptical flow. The clustering of color sources provides a framework ...of partonic interactions. In this scheme, we show a reasonable agreement with RHIC data for pT < 1.5 GeV/c in both the dependence of v2 on transverse momentum and in the shape of the nuclear modified factor on the azimuthal angle for different centralities. We show the predictions at LHC energies for Pb-Pb. In the case of proton-proton collisions, a sizable v2 is obtained at this energy.
In the framework of percolation of strings, the transverse momentum distributions in AA and hh collisions at all centralities and energies show a universal behavior. The width of these distributions ...is related to the width of the distribution of the size of the clusters formed by the overlapping of the strings produced. The difference between the distributions for baryons and mesons originates in the fragmentation of clusters of several strings, which enhances the particles with a higher number of constituents. The results agree with SPS and RHIC data. The predictions for LHC show differences for baryons compared with RHIC. At LHC energies we obtain also a high p
T
suppression for pp high multiplicity events compared with the pp minimum bias.
We present results of a search for two hypothetical strange dibaryon states, i.e. the H-dibaryon and the possible Λn‾ bound state. The search is performed with the ALICE detector in central (0–10%) ...Pb–Pb collisions at sNN=2.76 TeV, by invariant mass analysis in the decay modes Λn‾→d‾π+ and H-dibaryon →Λpπ−. No evidence for these bound states is observed. Upper limits are determined at 99% confidence level for a wide range of lifetimes and for the full range of branching ratios. The results are compared to thermal, coalescence and hybrid UrQMD model expectations, which describe correctly the production of other loosely bound states, like the deuteron and the hypertriton.
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