Bottomonium first results from LHC experiments Nuno Leonardo - PowerPoint PPT Presentation

Bottomonium first results from LHC experiments Nuno Leonardo (Purdue University) for the LHC Collaborations XIV International Conference on Hadron Spectroscopy Hadron2011 Munich, June 15, 2011

overview introduction di-lepton signals • LHC • μμ , ee spectra • motivations • detector resolution pp @ 7TeV PbPb @ 2.76TeV • data-driven efficiency • R AA, cross section • cross section • ϒ ’ suppression • prospects N. Leonardo HADRON’2011 bottomonia@LHC, 2

LHC luminosity [lpc.web.cern.ch] ! b -1 f pp@7TeV PbPb@2.76TeV pp@2.76TeV 2011 (2010) . ALICE, ATLAS, CMS: L~9 μ b -1 ATLAS, CMS: L~ 241 nb -1 ATLAS, CMS: L~1k (40) pb -1 LHCb: L~ 67 pb -1 LHCb: n/a LHCb: L~300 (40) pb -1 ALICE: L <1 pb -1 ALICE: L~2 (<1) pb -1 L pp ≈ 10 30 - 10 33 cm -2 s -1 L PbPb ≈ 10 25 - 10 27 cm -2 s -1 N. Leonardo HADRON’2011 bottomonia@LHC, 3

ALICE, ATLAS, CMS, LHCb N. Leonardo HADRON’2011 bottomonia@LHC, 4

LHC experiments (cont’d) • all four detectors have the capability to study bottomonia • complementary phase space and physics coverage ‣ e.g. central vs forward rapidities, pp vs heavy-ion environments • based on different: B field, detector technologies, DAQ capabilities, emphasis on hermeticity or particle ID N. Leonardo HADRON’2011 bottomonia@LHC, 5

then... & now Fermilab Summer 1977 CERN, Summer 2010 ... a spectroscopists delight! N. Leonardo HADRON’2011 bottomonia@LHC, 6

large set of results BaBar: ϒ (3S) →η b (1S) γ CESR- 1980/90s CUSB, CLEO PEPII/KEKB-2000s BaBar, Belle Z b →ϒ (nS) π ± ➥ ➥ Tevatron-2000s D0 CDF, D0 CDF 1.3 fb -1 2.9 fb -1 Belle: ϒ (5S) → ϒ (2S) ππ (Bottomonium-like exotica: 2 charged states just above open beauty B * B, B * B * thresholds) N. Leonardo HADRON’2011 bottomonia@LHC, 7

bottomonium spectroscopy direct production indirect production contribution from feed down transitions from heavier bottomonia ➥ 30-50% of full ϒ (1S) productions no contribution from long-lived states (below open beauty threshold) N. Leonardo HADRON’2011 bottomonia@LHC,

phenomenology • heavy quarkonia constitute an ideal laboratory for testing interplay between perturbative and non-perturbative QCD • bottomonium (and in general, quarkonium) production not satisfactorily understood ‣ theoretically and experimentally puzzling • no theory has simultaneously explained Tevatron measurements of both cross section and polarization ‣ non-relativistic QCD (incl. color octet), color singlet model, color evaporation model, etc T L (note: NNLO * is not a complete NNLO, (note: drastic change of CSM predicted possibility of large uncanceled logs) polarization from LO to NLO/NNLO * ) N. Leonardo HADRON’2011 bottomonia@LHC, 9

bottomonia at the LHC? • phenomenology ‣ large b -quark mass ➩ non-relativistic effective approaches better realized ‣ no feed-down from long-lived b -hadrons • unprecedented energy regime ‣ extended reach, eg probe p T >20GeV, best discriminate between models ‣ high cross section (and luminosity) ➩ bottomonia produced copiously ‣ allow new era of bottomonium precision measurements • heavy ion ‣ 1 month per year dedicated to heavy-ion physics run ‣ cross sections ~50 times larger, energy density ~3 times higher than at RHIC ➩ will allow first significant measurements of the ϒ resonance family ‣ improve overall understanding of the cold and hot nuclear matter effects ‣ LHC calls for precision studies of bottomonia at high temperature N. Leonardo HADRON’2011 bottomonia@LHC, 10

di-lepton signals

LHCb L~0.6pb - 1 N ϒ ≈ 48k N. Leonardo HADRON’2011 bottomonia@LHC, 12

ATLAS N ϒ ≈ 23k N. Leonardo HADRON’2011 bottomonia@LHC, 13

CMS N 1S =23,390±194 N 1S =7,298±133 μμ N 1S =3,999±113 N ϒ ≈ 138k (| η |<2.4) ) 2 CMS Preliminary Events/(GeV/c 3 J/ 10 � PbPb s = 2.76 TeV (1,2,3S) NN � -1 L = 7.28 µ b int 2 10 PbPb@2.76TeV ee 10 Z μμ 1 µ p > 4.0 GeV/c T 2 10 10 2 N. Leonardo HADRON’2011 bottomonia@LHC, 14 m (GeV/c ) µ µ

momentum/mass resolution Alice Atlas L~13 nb -1 σ ~46MeV | η | < 0.8 (up to 110 MeV at higher rapidities) σ ~94MeV CERN-PH-EP-2011-041 CERN-PH-EP-2011-057 LHCb CMS L~5.2 pb -1 σ ~13 MeV σ ~21MeV (up to 50 MeV at higher rapidities) CMS-PAS-TRK-10-004 CERN-PH-EP-2011-018 CERN-PH-EP/2010-046 N. Leonardo HADRON’2011 bottomonia@LHC, 15

｜ ｜ ｜ ｜ ⎛ ｜ ｜ ｜ ｜ ｜ ⎝ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ⎝ ｜ ｜ ｜ ⎛ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ ｜ prior expectations (before LHC startup) ATLAS simulation ALICE simulation arXiv:nucl-ex/0702045v1 CMS simulation LHCb simulation N. Leonardo HADRON’2011 bottomonia@LHC, 16

pp @ 7TeV • LHCb-CONF-2011-016, 32pb -1 • CMS-BPH-10-003 (arXiv:1012.5545,PRD), 3pb -1 ➪ see also talks by B.Akgun and G.Sabatino on Tuesday parallel session Quarkonia/3

cross-section ingredients 4.5 1 (1S) Acceptance CMS LHCb LHCb ! 0.9 y of 4 e c 0.8 n a t p e c 3.5 c A 0.7 0.6 3 0.5 2.5 0.4 0.3 2 0 2 4 6 8 10 12 14 p of (1S) (GeV/c) ! T s d l e i y l a n g i s LHCb y c n e i c i f f ε polarization: CMS N. Leonardo HADRON’2011 bottomonia@LHC, 18

ϒ (nS) differential cross sections dy [nb/(GeV/c)] 10 1 ϒ (1S) unpolarized -1 T 10 (1S)X)/dp -2 10 LHCb 2.0 < y < 2.5 2.0 < y < 2.5 stat+syst Preliminary 2.5 < y < 3.0 2.5 < y < 3.0 ! " 3.0 < y < 3.5 3.0 < y < 3.5 no lumi. -3 s = 7 TeV 10 (pp 3.5 < y < 4.0 3.5 < y < 4.0 $ -1 4.0 < y < 4.5 4.0 < y < 4.5 L = 32.4 pb # 2 -4 d 10 0 2 4 6 8 10 12 14 p of (1S) (GeV/c) ! T LHCb (|y|<2) CMS (unpolarized case) ϒ (2S)/ ϒ (1S): 0.26±0.02±0.04 ϒ (3S)/ ϒ (1S): 0.14±0.01±0.02 N. Leonardo HADRON’2011 bottomonia@LHC, 19

comparison: theory N. Leonardo HADRON’2011 bottomonia@LHC, 20

comparison: experiment LHC LHC vs Tevatron N. Leonardo HADRON’2011 bottomonia@LHC,

polarization • detector acceptance sensitive to unknown polarization ➭ σ ( ϒ ) variations of about 20% • measure full angular distribution of leptons • in complementary reference frames • also frame independent • results binned in p T and rapidity • measurements being currently finalized ➙ Acceptance test λ ’s N. Leonardo HADRON’2011 bottomonia@LHC, 22

other measurements, prospects • prompt bottomonium reconstruction includes feeddown from higher states L~36pb -1 ‣ eg 40-50% of ϒ (1S) production from decays LHCb- CONF-2011- of excited 2S,2P,3S states [CDF,
PRL84
(2000)
2094] 020 ‣ desirable to separate direct production ‣ eg reconstruct χ b → ϒ γ decays (plots show examples already achieved for charmonia) ‣ L~40pb -1 • search for exotica, bottomonia-like states? • ➭ more data required ATLAS X(3872) simulation N. Leonardo HADRON’2011 bottomonia@LHC, 23

PbPb @2.76TeV • CMS-PAS-HIN-10-006 • CMS-HIN-11-007 (arXiv:1105.4894, submitted PRL) n o l i s p U . . n a o . k i . s a s e r p p u s

bottomonia as QGP probe • at high temperatures, strongly interacting matter becomes a plasma of quarks and gluons • suppression of quarkonia is a classical prediction of QGP signature ‣ color screening of the binding potential [ T .Matsui, H.Satz PLB178, 416 (1986) ] ‣ suppression pattern indicates the medium temperature ( ‘QGP thermometer’ ) ‣ role of cold nuclear matter effects also emphasized at SPS and RHIC • bottomonium measurements at LHC help characterize the dense matter produced in heavy-ion collisions beyond the SPS and RHIC charmonium results ‣ the ϒ family of states is an expected powerful probe ‣ ϒ (1S) is the most tightly bound state ➪ last to melt down ‣ provide 3 different states/handles for probing the hot medium • quantitative bottomonium measurements accessible for first time ‣ large production rates ➪ sizable datasets ‣ exploit excellent mass resolution ‣ T C ~ 150-170MeV Sequential melting decreasing binding energy N. Leonardo HADRON’2011 bottomonia@LHC, 25

datasets PbPb pp PbPb run 2010 @2.76TeV (7.28 μ b -1 ) pp run 2011 @2.76TeV (225 nb -1 ) • same online+offline selection applied to both datasets • muon selection: quality cuts, p T >4GeV/c, | η μ |<2.4 N. Leonardo HADRON’2011 bottomonia@LHC, 26

invariant yields l a e n c g i n s a t p s e c d l c e A i y 7 10 CMS PbPb s =2.76 TeV NN 6 10 Minimum Bias Trigger 5 Dimuon Trigger 10 Number of events 4 10 3 10 2 10 10 y c 1 n e i c 100 80 60 40 20 0 i f f Centrality % ε N. Leonardo HADRON’2011 bottomonia@LHC, 27