Ridges from the Glasma Entangled glue and collective

Ridges from the Glasma: Entangled glue and collective flow Raju Venugopalan Brookhaven National Laboratory WWND 2014, Galveston, TEXAS

What are we trying to learn? u What is the underlying QCD mechanism of the ridge? u Is there “spooky quantum mechanics” at work a la photon or spin entanglement ? u How far can we extend the collective flow paradigm – and do we see systematic deviations? u Are hadronization patterns universal QCD physics or do they reflect thermal abundances Cool, exciting stuff experiments are beginning to answer

What all ridges share across system size • Systematic dependence on multiplicity of event • Long range near and away side rapidity correlations • Azimuthal anisotropies, decomposed into Fourier harmonics • Similar (? ) hadronization patterns

What ridges do not share across system size A) Mini-jets patterns are very different: i) Completely un-modified in p+p high multiplicity events ii) Strongly modified in A+A iii) Jury out in p+A. Answer depends on p. T window of interest B) Dissimilar (? ) hadronization patterns – p/π and K/π ratios are more alike than not in p+p and p+A -- show significant changes for more central A+A events C) HBT radii: significantly different slopes in p+p and A+A. Just out—p+A slopes are close to p+p (ALICE results: 1404. 1194) Event structure not identical in p+p, p+A, A+A -- gloss over these differences at your peril

Multiparticle production in p+p What does it take to produce ~ 150 hadrons per 5 units of rapidity in a single p+p event ? What’s the guidance from HERA?

Multiparticle production What does it take to produce ~ 150 hadrons per 5 units of rapidity in a single p+p event ? For λ=0. 14, get about 13 gluons produced in 5 units ~ min. bias hadron multiplicity λ=0. 3: ~45 gluons in 5 units, λ=0. 4: ~90 gluons in 5 units, in ball park… Very rapid growth of gluon dist. in such events…

The proton in a high multiplicity event Y=ybeam π π π Y=0 π π π For Q 2= 2 Ge. V 2, , what’s the proton’s gluon radius?

The proton in a high multiplicity event Y=ybeam π π π Y=0 π π π For Q 2= 2 Ge. V 2, , what’s the proton’s gluon radius? Gribov diffusion => R 2 ~ ln(s) Rg grows much faster depending on Ng rate --will violate unitarity Saturation regulates this by adding increasingly “smaller” gluons of size 1/Qs(x) with decreasing x

Lasing gluons: Stimulated emission from Glasma flux tubes Dumitru, Gelis, Mc. Lerran, RV (2008) Dusling, Fernandez-Fraile, RV (2009) Gelis, Lappi, Mc. Lerran (2009) Color combinatorics of cut graphs: a negative binomial distribution

Lasing gluons: Stimulated emission from Glasma flux tubes Dumitru, Gelis, Mc. Lerran, RV (2008) Dusling, Fernandez-Fraile, RV (2009) Gelis, Lappi, Mc. Lerran (2009) Color combinatorics of cut graphs: a negative binomial distribution k=1: Bose-Einstein dist. k=∞: Poisson distribution For QS 2 ≈ 1/ST close to a Bose-dist!

There are ~ πR 2 QS 2 flux tubes a: shattering CGCs Lappi 0711. 3039 Ng ~ 100 in 5 units for QS 2 ~ 2 Ge. V 2 To produce large # of particles, to satisfy constraints from Unitarity, Causality and Confinement requires a semi-hard scale. 1206. 6805 1311. 3636 Schenke, Tribedy, Venugopalan

2 particle correlations in p. QCD: counting powers

2 particle correlations in p. QCD: counting powers Gluons with k. T ~ QS resolve n ~ 1/g 2 color sources Effective coupling: g*n ~ 1/g Glasma graphs enhanced in high mult. events by αS-8

The saturated hadron: Glasma graphs Dumitru, Gelis, Mc. Lerran, RV: 0804. 3858 Gelis, Lappi, RV, ar. Xiv: 0807. 1306 Weights give energy dependence of large x sources From solns. of Yang-Mills eqns. with two light cone sources Includes all mult. scat. contributions (gρ1)n and (gρ2)n Caveat: valid for Δypq < 1/αS

Glasma graphs-key features Glasma graphs generate long range rapidity correlations Suppressed for QS << p. T by powers of αS AND NC (At high p. T, large x or large impact parameters) Glasma graphs enhanced by 1/αS 8 for high occupancy fields -- factor of 105 for typical αS ! (central impact parameters, small x, low p. T, large nuclei)

Angular structure from (mini-) Jet radiation p GBFKL q NLO in the dense-dense framework but… unsuppressed in NC Caveat: does not include multiple scattering contributions which may be significant for k. T < QS

Anatomy of long range collimation

Quantitative description of pp ridge Dusling, RV: PRL 108 (2012)262001 Dependence on transverse area cancels in ratio… Caveat: k. T factorized approximation used for quantitative comparisons – mult. scatt. contributions, of same order, important for k. T < QS

Quantitative description of pp ridge Dusling, RV: PRL 108 (2012)262001 Dependence on transverse area cancels in ratio… Rarer and rarer gluon configurations probed in the proton

Systematics of p+p correlated yield Data from CMS collaboration Fits: Dusling, RV, ar. Xiv: 1302. 7018

Dusling, RV, PRD 87, 051502 (R) (2013); ar. Xiv: 1302. 7018

What about p+A ? Ridge much bigger than p+p for the same multiplicity p+A ridge nearly as large as peripheral Pb+Pb

Systematics of associated yield in p+Pb Q 0 2(lead)=N Part Pb * Q 0 2(proton) Dusling, RV: 1302. 7018 # of “wounded” nucleons in lead nucleus Very large Ntrk in p+Pb is probing very rare configurations inside proton

LHC p+A vs A+A collisions Peripheral A+A Central p+A

Further systematics of p+Pb associated yield Dusling, RV: 1211. 3701 1302. 7018

Anatomy of long range di-hadron collimation BFKL Mini-jet Glasma graphs Associated Di-hadron Yield

“Jet subtracted” p+Pb ridge Similar subtraction in RHIC d+Au to extract ridge

v 3 in LHC p. A collisions CMS 1305. 0609 v 3 > 0 not obviously obtained from Glasma graphs in k. T factorization approximation Only even moments obtained…

Are there sources of v 3 in the Glasma? CGC/Glasma yield Jet/Glasma Interference Jalilian-Marian, Kovchegov Baier, Kovner, Nardi, Wiedemann Fukushima, Hidaka Iancu, Laidet “p. QCD” jet Jet/Glasma interference term –assumed small previously

Are there sources of v 3 in the Glasma? Dusling+RV, in preparation Glasma graphs Jet graph We recently finished a computation of this long range quantum interference contribution Jet-Glasma quantum interference

Triangular azimuthal anisotropy in p+A collisions Does this generate positive a 3 ?

Triangular azimuthal anisotropy in p+A collisions

Triangular azimuthal anisotropy in p+A collisions

Triangular azimuthal anisotropy in p+A collisions Sym: same QS 0, as in A+A peripheral collisions Asym: unequal QS 0 in projectile and target as in p+A

Conclusions u The Glasma framework allows for systematic study of multi-particle production in p+p, p+A and A+A collisions u The p+p ridge can be quantitatively understood from gluon saturation enhanced quantum interference Glasma graphs + BFKL graphs u The A+A ridge and vn moments are quantitatively described in the same framework by IP-Glasma initial conditions + flow (See Bjoern Schenke’s talk tomorrow for the latest)

Conclusions u The p/d+A ridge situation is not fully clear u 2 -part corr. data are described by Glasma+BFKL dynamics within systematic uncertainties. u We showed here that a triangular azimuthal anisotropy is generated by quantum interference effects. 4 and higher point anisotropies can also be computed, though the computation is challenging.

The Glasma: shattering CGCs Ø Extreme multi-particle production requires a universal semi-hard scale in the proton of order few Ge. V Ø High occupancy=> particle production described by classical fields Ø Approximately boost invariant

Color correlations: Glasma graphs Leading correlated graph ~ 1 / αS 2 NC 2 Distributions fall as ~ QS 4/p. T 4 * QS 4/q. T 4

Systematics of p+p correlated yield Data from CMS collaboration Fits: Dusling, RV, ar. Xiv: 1302. 7018

d+Au ridge at RHIC

d+Au ridge at RHIC

d+Au ridge at RHIC

d+Au ridge at RHIC

d+Au ridge at RHIC PHENIX, 1303. 1794

d+Au ridge at RHIC But: does a d+Au ridge exist at RHIC ? Talk by Fuqiang Wang, RBRC workshop, April 15, 2013 STAR argues nearside ridge goes away with increasing Δη … Where does this leave the hydro explanation ? Centrality dependence will be important…

Physics underlying the ridge Look at ratio of yield at Δφpq = 0 to Δφpq=π for |p. T|=|q. T| As seen in the LHC p+Pb data…

Long range di-hadron correlations Gelis, Lappi, RV (2009) Simplify using “Gaussian truncation” approximation to JIMWLK Dusling, Gelis, Lappi, RV: 0911. 2720

The saturated hadron: Glasma graphs-I RG evolution: + Dumitru, Gelis, Mc. Lerran, RV: 0804. 3858 Gelis, Lappi, RV, ar. Xiv: 0807. 1306 + … Keeping leading logs to all orders (NLO+NNLO+…) = LO graph with energy dependence of each evolved source described by weight functional W[ρ] Avg. over sources in each event and over all events gives correlation

Nearside collimation: quantum interference of glue Dumitru, Dusling, Gelis, Jalilian-Marian, Lappi, RV, ar. Xiv: 1009. 5295 RG evolved leading Glasma contribution expressed in terms of “unintegrated gluon distributions” in the proton Proton 1 Proton 2

Nearside collimation: quantum interference of glue Dumitru, Dusling, Gelis, Jalilian-Marian, Lappi, RV, ar. Xiv: 1009. 5295 RG evolved leading Glasma contribution expressed in terms of “unintegrated gluon distributions” in the proton Proton 1 Proton 2 Caveat: k. T factorized approximation to full RG simulation -- coherent multiple scattering effects – possibly large for k. T < QS -- not included

Nearside collimation: quantum interference of glue From RG evolution of BK equation Q 0

Collimated yield ? From RG evolution of BK equation Q 0 Dominant contribution from | p. T-k. T| ~ |q. T-k. T| ~ |k. T| ~ QS This gives a collimation for ΔΦ ≈ 0 and π

Are there sources of v 3 in the Glasma? For k. T ≤ QS: coherent multiple scattering contributions are important – all of same order in QCD coupling × × Not included in k. T factorization framework Can be computed by solving Yang-Mills equations for the Glasma Lappi, Srednyak, RV: 0911. 2068 In dilute-dense context, see Kovchegov, Wertepny, 1212. 1195

Can v 3 be obtained in the Glasma? Lappi, Srednyak, RV: 0911. 2068 Schenke, RV: in preparation IP-Glasma results are preliminary-no centrality selection, etc. In principle extract v 2{4} too— Systematic study for peripheral A+A feasible…

Long range di-hadron correlations Gelis, Lappi, RV (2009) Simplify using “Gaussian truncation” approximation to JIMWLK Dusling, Gelis, Lappi, RV: 0911. 2720