Correlated wounded hot spots in proton-proton interactions

Abstract

We investigate the effect of non-trivial spatial correlations between proton constituents, considered in this work to be gluonic hot spots, on the initial conditions of proton-proton collisions from ISR to LHC energies, i.e. $\sqrt s\!=\!52.6,7000,13000$ GeV. The inclusion of these correlations is motivated by their fundamental role in the description of a recently observed new feature of $pp$ scattering at $\sqrt s\!=\!7$ TeV, the hollowness effect. Our analysis relies on a Monte-Carlo Glauber approach including fluctuations in the hot spot positions and their entropy deposition in the transverse plane. We explore both the energy dependence and the effect of spatial correlations on the number of wounded hot spots, their spatial distribution and the eccentricities, $\varepsilon_n$, of the initial state geometry of the collision. In minimum bias collisions we find that the inclusion of short range repulsive correlations between the hot spots reduces the value of the eccentricity ($\varepsilon_2$) and the triangularity ($\varepsilon_3$). In turn, upon considering only the events with the highest entropy deposition i.e. the ultra-central ones, the probability of having larger $\varepsilon_{2,3}$ increases significantly in the correlated scenario. Finally, the eccentricities show a quite mild energy dependence.Comment: Manuscript restructured and extended to include a centrality study and probability distributions instead of averages . Accepted for publication in Phys. Rev.

Symmetric cumulants as a probe of the proton substructure at LHC energies

“…However, as these configurations are enhanced in the correlated scenario, the anti-correlation of ε 2 and ε 3 is stronger than in the uncorrelated case just as in the case of N hs = 3. Finally, we have checked that the effect of spatial correlations on the average values of ε 2 and ε 3 is qualitatively the same as in the N hs = 3 case studied in [1]. To sum up, although the negative sign of NSC (2,3) in the highest centrality bins is not a unique feature of the correlated scenario but relies on the interplay of the different scales, the inclusion of repulsive correlations provides a mechanism to reduce its value in the highest centrality bins.…”

“…We dub each (N w , N coll )configuration as interaction topology. In our case, given that we consider the proton to be formed by three hot spots N w ∈ [2,6] and N coll ∈ [1,9].…”

“…In the context of heavy ion collisions, a very recent tool to study the properties of the Quark Gluon Plasma (QGP) are the correlations between different flow harmonics v n i.e. the symmetric cumulants defined as [2,3] SC(n, m) = v 2 n v 2 m − v 2 n v 2 m (1) or in their normalized version…”

Bayesian calibration of a hybrid nuclear collision model using p−Pb and Pb-Pb data at energies available at the CERN Large Hadron Collider

“…Measurements by the TOTEM collaboration at √ s = 7 TeV, for instance, found an unexpected dip in the inelasticity density of p-p collisions at zero impact parameter [34]. It was later realized that this depression, or so-called hollowness effect, in the p-p inelastic collision profile [35] can be explained by the existence of correlated domains inside the proton, and that aspects of these domains, such as their size and correlation strength, may be constrained by comparing model predictions to inelastic p-p measurements [36,37].…”

Correlated gluonic hot spots meet symmetric cumulants data at LHC energies

“…3 [10]. Noticeably, the imprints of the spatial correlations are visible in the case of the elliptic flow that is enhanced in the correlated scheme as it was the case for the eccentricity [9]. In turn, v 3 , with the current statistical precision, is compatible in both scenarios.…”