bottomonia in aa collisions…

Bottomonia in AA collisions…

Raphaël Granier de CassagnacLLR – École polytechnique / IN2P3

ERC grant “QuarkGluonPlasmaCMS”

SaporeGravi(s), Dec. 3rd 2013, Nantes

Quarkonium suppression

• Old predicted signature of the QGP– Quarkonia should melt one after the

other, depending on their binding energy

– Recent example of melting temperatures

• In an ideal world, they could serve as a thermometer of the plasma– With one grade per measured

quarkonium…– Potentially five at LHC: ψ, ψ’, Y(1S),

Y(2S), Y(3S)

03/12/2013 [email protected] - Bottomonia - SaporeGravi(s) 2

Matsui & Satz,PLB168 (1986) 415

Mocsy, EPJC61 (2009) 705

ϒ(1S)

χb

J/ψ, ϒ(2S)

χc, χ’b, ψ', ϒ(3S)

Bottomonia vs Charmonia

• One major drawback– About 200 times less Y(1S)μμ than J/ψμμ

• A few advantages, in the thermometer context– Theorists prefer heavier stuff– Less regeneration

• More than 100 charm pairs in central PbPb @ 2.76 TeV• Typically 20 times less beauty (was 200 at RHIC)

– Y(1S) should be the most plasmaproof (lowest grade)– No feed-down from open flavours, only from higher bottomonia

(in particular χb)– Three states close in production x branching ratio

• 7 / 2 / 1 (in pp collisions at 7 TeV)• While ψ/ψ’ is more like 50 / 1


Numbers extracted from various ALICE, CMS and LHCb publications

Bottomonia vs Charmonia


CMS, JHEP 02 (2012) 011 & Phys.Rev.D83:112004,2011

Just an illustration…

Feed-down contributions

• Not well known, two measurements at high pT:– CDF @ 1.8 TeV, pT > 8 GeV, |η| < 0.7

(50.9 ± 8.2 ± 9.0)% of Y(1S) coming from feeddown• (27.1 ± 6.9 ± 4.4)% from χb(1P) ϒ(1S) γ (measured)• (10.5 ± 4.4 ± 1.4)% from χb(2P) ϒ(1S) γ (measured)• (10.7 +7.7

–4.8 )% from ϒ(2S) ϒ(1S) ππ (σ x BR)• (0.8 +0.6

–0.4 )% from ϒ(3S) ϒ(1S) ππ (σ x BR)• < 6% from χb(3P) (then unobserved) ϒ(1S) γ

– LHCb @ 7.0 TeV, 6 < pT < 15 GeV, 2.5 < y < 4.0• (20.7 ± 5.7 ± 2.5 –5.4

+2.7)% from χb(1P) ϒ(1S) γ


CDF, PRL84 (2000) 2094LHCb, JHEP11 (2012) 031

Feed-down contributions

• Not well known, two measurements at high pT:– CDF @ 1.8 TeV, pT > 8 GeV, |η| < 0.7

(50.9 ± 8.2 ± 9.0)% of Y(1S) coming from feeddown• (27.1 ± 6.9 ± 4.4)% from χb(1P) ϒ(1S) γ • (10.5 ± 4.4 ± 1.4)% from χb(2P) ϒ(1S) γ • (10.7 +7.7 –4.8 )% from ϒ(2S) ϒ(1S) ππ • (0.8 +0.6

–0.4 )% from ϒ(3S) ϒ(1S) ππ • < 6% from unobserved χb(3P)

– LHCb @ 7.0 TeV, 6 < pT < 15 GeV, 2.5 < y < 4.0• (20.7 ± 5.7 ± 2.5 –5.4

+2.7)% from χb(1P) ϒ(1S) γ


CDF, PRL84 (2000) 2094LHCb, JHEP11 (2012) 031

The last feed-down


ATLAS, PRL108 (2012) 341

All three χb(1P), (2P) and (3P) ϒ(1S) γ(aka the χb(3P) discovery)Dimuon pT > 12 GeV and |y|<2.0 The last contribute less than the two first

Early pA measurements

• E772, Y(1S) & Y(2S+3S) in p+d, C, Ca, Fe & W collisions @ 39 GeV– Less suppression than charmonia– Compatible for 1S and 2S+3S– Including large xF domain– (reminder: σA= σN x Aα)– (warning: the pd reference was

not confirmed by E866, but nuclear dependence should be Ok)


E772, PRL66 (1991) 2285, plots from M. Leitch(Y(1S) also NA50 with less statistics and ~ 1)α

A first (preliminary) AA measurement

• RAA < 0.64 @ 90%– In [9.5;11.5] GeV/c2

– Whatever it was…


@ RHIC

Mixed Y(1S+2S+3S) at RHIC in dAu

• Statistically very limited…


PHENIX, dAu: PRC87 (2013) 044909

rapidity, d-going side

from PHENIX

Mixed Y(1S+2S+3S) at RHIC in AuAu


STAR preliminary, paper to appear tomorrow on arXiv on AuAu and dAu

Roughly a 50% suppression, that could reflect the meltingof the excited states only…

from STAR

Also preliminary is RdA (1S+2S+3S) = 0.78 ± 0.28 ± 0.20

Now, let’s move to the LHC and change the name of the workshop to…


SAPORIBUS GRAVIBUSNow, let’s move to the LHC and change the name of the workshop to…


First, an “indication” of Y(2S+3S) suppression


The first published paper already had the three statesthanks to the first pp run @ 2.76 TeV

CMS,

PR

L107

(20

11)

0523

02

First, an “indication” of Y(2S+3S) suppression


About 2.4σaway from 1

CMS,

PR

L107

(20

11)

0523

02

Then, the “observation”


CMS,

PR

L109

(20

12)

2223

01

Second PbPb run, 20 x more statistics 1S and 2S vs centrality 3S upper limit

But forget double ratio…

Nuclear modification factors of 1S, 2S & 3S


Sequential disappearance of the 3 states

For minimum biasRAA (Y(1S)) = 0.56 ± 0.08 ± 0.07RAA (Y(2S)) = 0.12 ± 0.04 ± 0.02RAA (Y(3S)) < 0.10 @ 95% CL

Here also, this is not inconsistentwith the melting of only the

excited states…

Now let’s look at the kinematics…

CMS, PRL109 (2012) 222301+ ALICE, preliminary

Y(1S) vs y and pT from CMS


From CMS results based on the first PbPb and pp @ 2.76 TeV, I once said: - Need more statistics, but suppression may be localised towards lower pT and yThe second PbPb and pp @ 2.76 TeV runs have 20 x more, analysis underway…

CMS, JHEP05 (2012) 063

Y(1S) vs y and pT from CMS+ALICE


From ALICE preliminary result, based on the second PbPb run and pp intrapolation:The suppression is not localised at midrapidity

CMS, JHEP05 (2012) 063ALICE, preliminary

Comparison with theory (1/2)

• Multicomponent model:– Proxy for nuclear effect: 0 to 2

mb absorption cross section– Rate equation in the fireball

with suppression and regeneration

• Reproduce both 1S & 2S– Funny enough a significant

part of the very few remaining 2S is attributed to regeneration

– Very few Y vs open flavour


CMS, PRL109 (2012) 222301 vs. Emerick, Zhao, Rapp, EPJA48 (2012) 72

Comparison with theory (1/2)


CMS, PRL109 (2012) 222301 and ALICE preliminary vs. Strickland, 1205.5327

• Pure thermal suppression in anisotropic hydro, using CDF feeddowns (51% direct Y(1S)…), no cold effects…

Works well for CMS and ALICE separatelyBut predict lower suppression at forward rapidity…

Conclusions

• Just the beginning of bottomonium studies… – At first sight, compatible with maximum melting of excited

states, and resilience of the ground state…More PbPb data is needed (so far 50 – 100% centrality)Kinematical dependencies from existing pp data analysis

• But what’s going on in pPb?, see Nicolas’ & Igor’s talks this afternoon… A preview:– A mild suppression (much less than in PbPb)– But a multiplicity dependence, also seen in pp!… that could be due to more activity produced with the ground states More study vs pp multiplicity is needed (e.g., at 7 TeV)


Five grades?


CMS @ QM’12

Forgetting low pT J/ψ and ψ’(regeneration?) for a while…

RAA(MB) vs binding energylooks ordered…

TBD with more data vs centrality and unfolding

cold effects (pA) & feeddown

Could they start acting as athermometer?

Watch out for pT…

An epitaph for our review?Causa plasma, ad dirumpendo et mutando saporem gravem


BACK UP


Some xsections


E772, kinematics


Upsilon in Au+Au

• RAA < 0.64 @ 90%– In [9.5;11.5]GeV/c2

– Whatever it is…


The “indication”


Alice pp interpolation


Bossù @ hard probes 2013

bottomonia in aa collisions…

Documents