Related papers: On the double-ridge effect at the LHC
Measurements of charged dihadron angular correlations are presented in proton-proton (pp) and Lead-Lead (PbPb) collisions, over a broad range of pseudorapidity and azimuthal angle, using the CMS detector at the LHC. In very high…
I present an overview of the ridge phenomenon in proton-proton and proton-lead collisions. This novel collimation between rapidity separated hadron pairs is a consequence of non-linear gluon dynamics within the small-x wave-function of the…
Mechanisms proposed to explain the jet-related correlation of long range in rapidity (the ridge) observed in high-energy heavy-ion collisions are reviewed. Limitations of a model using the combined effect of transverse flow and a direction…
We investigate long range rapidity correlations of pairs of prompt photon and jet in the Color Glass Condensate (CGC) framework in proton-proton and proton-nucleus collisions at RHIC and the LHC. We show that photon-jet correlations exhibit…
This study presents the first observation of ultra-long-range two-particle azimuthal correlations with pseudorapidity separation of ($|\Delta \eta| > 5.0$) in proton-proton (pp) and ($|\Delta \eta| > 6.5$) in proton-lead (p-Pb) collisions…
In recent years certain experimental results from small collision systems (e.g. p-p, d-Au, p-Pb) at the RHIC and LHC have been reinterpreted as evidence for formation therein of a dense flowing medium (QGP) despite small collision volumes.…
We report on the studies of two-particle angular correlations measured in proton-proton collisions at a center-of-mass energy of sqrt(s) = 7 TeV recorded by ALICE at the LHC. Two-particle correlations in relative azimuth ({\Delta}{\phi})…
The CMS collaboration at the LHC has reported a remarkable and unexpected phenomenon in very high-multiplicity high energy proton-proton collisions: a positive correlation between two particles produced at similar azimuthal angles, spanning…
We report on two-particle charge-dependent correlations in pp, p-Pb, and Pb-Pb collisions as a function of the pseudorapidity and azimuthal angle difference, $\mathrm{\Delta}\eta$ and $\mathrm{\Delta}\varphi$ respectively. These…
We discuss the general mechanism leading to long-range rapidity and angular correlations produced in high energy collisions (the "ridge"). This effect naturally appears in the high energy QCD and is strongly sensitive to physics of the…
Particle production in small systems (pp and p-Pb collisions) has unveiled unexpected collective-like behavior. In this work an overview of the current investigation on the similarities between small systems and heavy-ion collisions is…
The observation in small size collision systems, $pp$ and $p$A, of strong correlations with long range in rapidity and a characteristic structure in azimuth, the ridge phenomenon, is one of the most interesting results obtained at the Large…
A very recent paper by the CMS collaboration \cite{cms_ridge} has created large discussion in the media, which call it important but did not explain why, in some places even calling it "unundestandable". While it is of course too soon to…
Two-particle transverse momentum differential correlators, recently measured in Pb--Pb collisions at energies available at the CERN Large Hadron Collider (LHC), provide an additional tool to gain insights into particle production mechanisms…
We present measurements of two-particle differential number correlation functions $R_{2}$ and transverse momentum correlation functions $P_{2}$, obtained from p-Pb collisions at 5.02 TeV and Pb-Pb collisions at 2.76 TeV. The results are…
We review the signatures for the soft collective dynamics in highest-multiplicity ultrarelativistic p-Pb collisions and show that the effects are well described in a three-stage model, consisting of the event-by-event Glauber initial…
It is shown that protons become more active at the periphery with increase of their collision energy. By computing the impact parameter distribution of the proton-proton overlap function at LHC energies and comparing it with ISR (and…
A study of the near-side ridge phenomenon in hadron-hadron collisions based on a cluster picture of multiparticle production is presented. The near-side ridge effect is shown to have a natural explanation in this context provided that…
We analyze the structure of the high multiplicity events observed by the CMS collaboration at the LHC. We argue that the bulk of the observed correlations is due to the production of a pair of jets with p_t > 15 GeV/c. We also suggest that…
The large multiplicities at the LHC may permit flow harmonics to be determined on an event by event basis in Pb-Pb collisions. We extract these harmonics from event by event di-hadron correlations. Within a fine centrality bin, we find the…