The ridge in proton–proton collisions at the LHC

Dumitru, Adrian; Dusling, Kevin; Gelis, François; Jalilian‐Marian, Jamal; Lappi, T.; Venugopalan, Raju

doi:10.1016/j.physletb.2011.01.024

Cited by 307 publications

(355 citation statements)

References 48 publications

Supporting

Mentioning

335

Contrasting

Order By: Relevance

“…Multiplicity distributions [7] derived from factorization theorems [8] in this framework are in good agreement [9,10] with recent LHC data [11]. Long range rapidity correlations of gluons computed in the CGC EFT [12] were previously shown to be in qualitative agreement [1] with the CMS di-hadron correlation data.…”

supporting

confidence: 73%

“…

…”

mentioning

confidence: 99%

See 1 more Smart Citation

Azimuthal Collimation of Long Range Rapidity Correlations by Strong Color Fields in High Multiplicity Hadron-Hadron Collisions

2012

Self Cite

View full text Add to dashboard Cite

The azimuthal collimation of di-hadrons with large rapidity separations in high multiplicity p+p collisions at the LHC is described in the Color Glass Condensate (CGC) effective theory [1] by N 2 c suppressed multi-ladder QCD diagrams that are enhanced α −8 S due to gluon saturation in hadron wavefunctions. We show that quantitative computations in the CGC framework are in good agreement with data from the CMS experiment on per trigger di-hadron yields and predict further systematics of these yields with varying trigger pT and charged hadron multiplicity. Radial flow generated by re-scattering is strongly limited by the structure of the p+p di-hadron correlations. In contrast, radial flow explains the systematics of identical measurements in heavy ion collisions.The discovery of di-hadron correlations in high multiplicity proton-proton collisions [2], long range in the angular (pseudo-rapidity) separation of the pairs relative to the beam axis and collimated in their relative azimuthal angle about this axis, provides significant insight into rare parton configurations in the proton and their dynamics in hadronic collisions.High multiplicity proton-proton collisions select "hot spot" configuations of wee gluon states in each proton. Quantum Chromodynamics (QCD) predicts that such hot spots have a maximum occupancy of order α −1 S [3, 4] (α S being the QCD fine structure constant), and have a typical size ∼ 1/Q S , where Q S is a dynamical saturation scale. This scale grows with the energy and centrality of the collision; when Q S ≫ Λ QCD , the fundamental QCD scale, highly occupied hadron wavefunctions can be described using weak coupling methods.A weak coupling effective field theory (EFT) that describes high density wee parton configurations in the proton is the Color Glass Condensate (CGC) [5]. When CGC's shatter in a high multiplicity collision, multiparticle production is a consequence of approximately boost invariant radiation from "Glasma flux tubes" of transverse size 1/Q S [6]. Multiplicity distributions [7] derived from factorization theorems [8] in this framework are in good agreement [9,10] with recent LHC data [11]. Long range rapidity correlations of gluons computed in the CGC EFT [12] were previously shown to be in qualitative agreement [1] with the CMS di-hadron correlation data.A source of long range rapidity correlations in hadronhadron collisions are back-to-back gluons emitted from a single t-channel gluon ladder; another source, called "Glasma graphs" are gluons emitted from two separate ladders. Representative graphs of each are shown in fig. (1). In the "dilute" high p T perturbative limit of QCD, the back-to-back contribution is dominant. However, at high parton densities, when Q 2 S ≫ Λ 2 QCD , and p 2 T ∼ Q 2 S , the effective coupling of gluons in ladders to strong color sources at higher rapidities changes from g → 1/g. This corresponds to an enhancement of Glasma graphs by α −8 S compared to the α −4 S enhancement of the back-to-back graphs. Equally important are the very different a...

show abstract

supporting

confidence: 73%

“…

…”

mentioning

confidence: 99%

Azimuthal Collimation of Long Range Rapidity Correlations by Strong Color Fields in High Multiplicity Hadron-Hadron Collisions

2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…The origin of such effects is still far from being understood, for instance, it has been shown that hydro calculations, where the formation of a hot and dense QCD medium is implicitly assumed, can describe qualitatively many features of data [7][8][9]. But, other approaches suggest that the phenomenon can be produced by initial state effects [10][11][12]. For instance, Pythia 8.180 [13] gives an effect reminiscent of the collective flow well known from heavy-ion collisions [14].…”

Section: Introductionmentioning

confidence: 99%

Mid-rapidity charged hadron transverse spherocity in pp collisions simulated with Pythia

2015

View full text Add to dashboard Cite

The pp collisions have been studied for a long time, however, there are still some effects which are not completely understood, such as the long range angular correlations and the flow patterns in high multiplicity events, which were recently discovered at the LHC. In a recent work it was demonstrated that in Pythia 8, multi-parton interactions and color reconnection can give some of the observed effects similar to the collective flow well known from heavy-ion collisions. Now using the same model, a study based on mid-rapidity charged hadron transverse spherocity is presented. The main purpose of this work is to show that a differential study combining multiplicity and event shapes opens the possibility to understand better the features of data, specially at high multiplicity.

show abstract

“…It was first postulated as an explanation of the high multiplicity CMS protonproton ridge in [11], and a quantitative description of the nearside collimated yield obtained in [12].…”

mentioning

confidence: 99%

Comparison of the color glass condensate to dihadron correlations in proton-proton and proton-nucleus collisions

2013

Self Cite

View full text Add to dashboard Cite

We perform a detailed comparison of long range rapidity correlations in the Color Glass Condensate framework to high multiplicity di-hadron data in proton-proton and proton-lead collisions from the CMS, ALICE and ATLAS experiments at the LHC. The overall good agreement thus far of the non-trivial systematics of theory with data is strongly suggestive of gluon saturation and the presence of subtle quantum interference effects between rapidity separated gluons. In particular, the yield of pairs collimated in their relative azimuthal angle ∆φ ∼ 0, is sensitive to the shape of unintegrated gluon distributions in the hadrons that are renormalization group evolved in rapidity from the beam rapidities to those of the measured hadrons. We present estimates for the collimated di-hadron yield expected in central deuteron-gold collisions at RHIC.

show abstract

The ridge in proton–proton collisions at the LHC

Cited by 307 publications

References 48 publications

Azimuthal Collimation of Long Range Rapidity Correlations by Strong Color Fields in High Multiplicity Hadron-Hadron Collisions

Azimuthal Collimation of Long Range Rapidity Correlations by Strong Color Fields in High Multiplicity Hadron-Hadron Collisions

Mid-rapidity charged hadron transverse spherocity in pp collisions simulated with Pythia

Comparison of the color glass condensate to dihadron correlations in proton-proton and proton-nucleus collisions

Contact Info

Product

Resources

About