Heavy flavour production measurement with ALICE at the LHC

Transcription

1 Heavy flavour producion measuremen wih ALICE a he LHC Francesco Bossù for he ALICE collaboraion ihemba LABS, Cape own Bormio, 5 Gen

2 Ouline Why heavy flavours HF wih he ALICE deecor HF in proon-proon collisions 4 HF in Pb-Pb collisions 5 Conclusions

3 Ouline Why heavy flavours HF wih he ALICE deecor HF in proon-proon collisions 4 HF in Pb-Pb collisions 5 Conclusions

4 Why heavy flavours in ALICE In proon-proon collisions: ˆ charm and beauy produced in high-q processes ˆ higher cross secion a he LHC σ c (LHC) 5 σ c (RHIC) σ b (LHC) 5 σ b (RHIC) ˆ Good es-bench for pqcd calculaions ˆ Reference for heavy-ion daa (µb) cc σ 4 ALICE (oal unc.) ALICE exr. unc. ALAS Preliminary (oal unc.) ALAS exr. unc. LHCb Preliminary (oal unc.) PHENIX SAR HERA B (pa) E65 (pa) E74 (pa) NA7 (pa) NA6 (pa) E769 (pa) NLO (MNR) JHEP 7 () 9 D c quark b quark B ALI PUB and being heavy-ion -minded: 4 s (GeV) ˆ heavy quarks largely produced in he early sages of he collision ( 6c c/collision) ˆ exposed o he medium evoluion ˆ no exraproducion a he hadronizaion Ideal probes F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen / 9

5 Probing he medium ˆ Parons loose energy in he medium via elasic collisions and gluon radiaion ˆ Medium-induced gluon radiaion depends on: medium properies and size paron colour charge (Casimir facor) paron mass (dead cone effec) Dokshizer and Kharzeev, PLB 59 (), 99 ˆ ools: Nuclear modificaion facor Azimuhal anisoropy E g > E u,d > E c > E b R AA = Y AA AA Y pp R AA (B) > R AA (D) > R AA (π) dn dϕ = N ( + vcos(ϕ Ψ) + vcos[(ϕ Ψ)] +... ) π collecive moions a low p and pah lengh dependence a high p F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen / 9

6 Ouline Why heavy flavours HF wih he ALICE deecor HF in proon-proon collisions 4 HF in Pb-Pb collisions 5 Conclusions

7 he ALICE experimen e ± π K µ ± ALICE in numbers ˆ members ˆ more han insiues ˆ counries ˆ 8 sub-deecors ˆ ons ˆ 6 6 6m Cenral Barrel ˆ η.9 ˆ Hadrons, elecrons and phoons ˆ p Muon Specromeer ˆ 4 η.5 ˆ Muons ˆ p muons > 4GeV /c Forward Deecors ˆ Large η ˆ Ineracion rigger ˆ Even characerizaion F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen / 9

8 Heavy flavours in ALICE c, b e + X ˆ Elecron idenificaion combining analyses wih differen PID sraegies: PC(dE/dx)+RD+OF and PC(dEdx)+EMCal ˆ Verexing wih he IS ˆ Background subracion: D mesons - Cockail: MC hadron-decay generaor for differen bkg sources - Elecron pair invarian mass: remove π, Daliz decays and phoon conversions ˆ Search for secondary displaced verices ˆ PID (π, K, p) a low-p for bkg reducion ˆ Signal exraced from invarian mass disribuion fis c, b µ ˆ Background muons from π and K decays: - pp: esimaed wih even generaors - PbPb: π and K measuremens a mid-rapidiy exrapolaed wih an hypohesis on R AA vs. η ˆ Fake racks from beam-gas ineracions subraced wih p DCA cu PC de/dx (arb. unis) e K p d π pp, s = 7 ev ALI PUB F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 4 / 9

9 Heavy flavours in ALICE - rigger and daa sample Sysem p-p p-p Pb-Pb Pb-Pb Energy (ev) (NN).76 (NN) Year L in MB 6 nb. nb. nb 8 nb L in MB (EMCal).6 nb.5 (.9)nb. nb (7)µb L in Muon 6.5 nb 9 nb.7 nb D mesons Elecrons Muons pp ˆ Minimum Bias (MB) rigger VZERO-A or VZERO-C or SPD ˆ Addiional EMCal and Muon rigger ˆ SPD: Silicon Pixel Deecor ˆ VZERO: Scinillaor arrays Pb-Pb ˆ Minimum Bias (MB) rigger, EMCal and Muon ˆ Cenraliy: Glauber fi o VZERO signal Evens Daa Glauber fi 7 8% 6 7% 5 5 6% 4 5% 4% % % 5 % 5% 5 5 ALI PUB 888 VZERO Ampliude (a.u.) PRL 6, () F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 5 / 9

10 Ouline Why heavy flavours HF wih he ALICE deecor HF in proon-proon collisions 4 HF in Pb-Pb collisions 5 Conclusions

11 ) pp - elecrons heavy flavours ) dy (mb/(gev/c) σ/dp ) d /(π p Daa/FONLL FONLL ALICE, (b+c) e pp s=.76 ev, η <.7, L =.9 nb in Addiional.9% normalizaion uncerainy p (GeV/c) ALI PREL dy) (mb/(gev/c) σ/(dp ) d /(πp pp, s = 7 ev ALICE c, b e ALAS c, b e FONLL c, b e, y <.5 FONLL c, b e, y < excl..7 < y <.5 ˆ Resuls boh a s =.76 and 7 ev ˆ Combined wo analyses: PC+RD+OF and PC+EMCal ˆ FONLL calculaions describe he daa wihin uncerainies over he full p range (Cacciari e al., arxiv:5.644) ˆ Nice complemenariy wih ALAS a high p Daa/FONLL ALI PUB 646 ALICE, Phys. Rev. D 86, 7 () ALAS, PLB 77 () 48 F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 6 / 9

12 ) pp - elecrons beauy ˆ s = 7 ev - y <.5 ˆ Furher e rack selecion via p dependen impac parameer d cu ˆ Charm exracion: subracion of he b conribuion o he inclusive specrum ˆ Beauy akes over from charm a abou 4 GeV/c ˆ FONLL pqcd predicions are in agreemen wihin uncerainies boh for he charm and he beauy differenial cross secion down o low-p (Cacciari e al., arxiv:5.644) couns PYHIA, s = 7 ev, y <.8 <p <6 GeV/c b ( c) e c e conversion elec. Daliz elec. (a) dy) (mb/(gev/c) σ/(dp ) d /(πp Daa/FONLL Daa/FONLL (a) pp, s = 7 ev, addiional.5% normalizaion uncerainy Ld =. nb b ( c) e c e FONLL b ( c) e FONLL c e (b) b ( c) e (c) c e Daa/MC ALI PUB 986 conversion elecrons Daa/MC <p < GeV/c Daa/MC <p <6 GeV/c d (µm) (b) b( c) e/c e.5 4 (d).5 oal uncerainy ALI PUB 98 arxiv:8.9 F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 7 / 9

13 5 5 5 p (GeV/c) p (GeV/c) p (GeV/c) pp - Open Charm a 7 ev (µb/gev/c) dσ / dp y <.5 ± sa. unc. sys. unc. FONLL GM VFNS.5% lumi, ± D, pp.% BR norm. unc. (no shown) s = 7 ev, L in ALICE = 5 nb (µb/gev/c) dσ / dp y <.5 ± sa. unc. sys. unc. FONLL GM VFNS.5% lumi, ± + D, pp.% BR norm. unc. (no shown) s = 7 ev, L in ALICE = 5 nb (µb/gev/c) dσ / dp y <.5 ± sa. unc. sys. unc. FONLL GM VFNS.5% lumi, ± *+ D, pp.5% BR norm. unc. (no shown) s = 7 ev, L in ALICE = 5 nb p GeV/c ALI PUB 5 Daa FONLL Daa GM VFNS p GeV/c JHEP () 8 ALI PUB 57 Daa FONLL Daa GM VFNS p GeV/c ALI PUB 5 Daa FONLL Daa GM VFNS c) (µb GeV y <.5 dσ / dp heory ALICE daa poins sa. unc. sys. unc. ± + Ds, pp.5% lumi, ± s = 7 ev, L in 5.% BR norm. unc. (no shown) ALICE = 4.8 nb heory predicions GM VFNS LO k fac Daa 4.5 GM VFNS Daa 4.5 LO k fac ALI PUB 4 Daa / arxiv:8.948 s = 7 ev ˆ D mesons p disribuion a mid-rapidiy ˆ D measured in < p < 6 GeV/c ˆ D + and D + measured in < p < 4 GeV/c ˆ D + s measured in < p < GeV/c ˆ pqcd calculaion describes he daa wihin uncerainies Cacciari e al., arxiv:5.644 Kniehl e al., arxiv:.49 Maciula, e al, arxiv:8.66 F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 8 / 9

14 pp - Open Charm a.76 ev (µb/gev/c) D meson + D meson pp s =.76 ev, L in ALICE =. nb *+ D meson y <.5 dσ / dp sa. unc. sys. unc. FONLL GM VFNS ±.9% lumi, ±.% BR norm. unc. (no shown) ±.9% lumi, ±.% BR norm. unc. (no shown) ±.9% lumi, ±.5% BR norm. unc. (no shown) heory 4 Daa / FONLL 4 4 Daa / 4 Daa / GM VFNS ALI PUB 576 p (GeV/c) s =.76 ev JHEP 7 () ˆ D mesons p disribuion a mid-rapidiy y <.5 ˆ pqcd calculaions describe he daa wihin uncerainies Cacciari e al., arxiv:5.644 Kniehl e al., arxiv:.49 F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 9 / 9

15 pp - µ heavy flavours a.76 and 7 ev ALI-PUB-6 PLB 78 () 65 (pb/.5 GeV/c) ± dσ µ HF /dp daa/fonll ALICE pp s=.76 ev, µ ± HF in.5<y<4 L in =9 nb daa µ ± HF, FONLL µ ± charm, FONLL µ ± beauy, FONLL.9% normalizaion uncerainy no included ALI PUB 675 PRL 9 () Muons from HF decays ˆ.5 < y < 4 ˆ background (µ π, K) subraced via MC simulaion normalised o daa a low-p ˆ pqcd calculaions describe boh he p and y disribuion wihin he uncerainies a boh energies Cacciari e al., arxiv:5.644 F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen / 9

16 Ouline Why heavy flavours HF wih he ALICE deecor HF in proon-proon collisions 4 HF in Pb-Pb collisions 5 Conclusions

17 Pb-Pb measuremens Nuclear modificaion facor R AA = AA YAA Y pp ˆ Y AA : yield of an observable (Y ) in AA collisions (i.e. dn/dp or dn/dy or...) ˆ Y pp: yield or cross secion of he same observable (Y ) in pp collisions a he same N-N energy in AA ˆ AA : average nuclear overlap funcion for he considered cenraliy inerval Azimuhal anisoropic flow dn dϕ = N π ( + v cos(ϕ Ψ ) + v cos[(ϕ Ψ )] +... ) ˆ ϕ is he azimuhal angle wih respec o he Ψ reacion plane angle ˆ v : ellipic flow ˆ c, b quark energy loss dependence on he pah-lengh non-zero v a high-p ˆ c, b collecive moions in medium non-zero v a low-p F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen / 9

18 Pb-Pb - R AA (p ) R PbPb (p ) = AA dn PbPb/dp dσ pp/dp Heavy flavour elecrons a mid-rapidiy ( y <.6) ˆ pp reference: ˆ p <8GeV/c: 7eV daa scaled o.76ev ˆ p >8GeV/c: FONLL pqcd calculaions ˆ Clear suppression in < p < 8GeV/c AA Heavy flavour decay elecrons R Pb Pb, s NN =.76 ev, % pp ref (scaled cross secion a 7 ev) pp ref (FONLL calculaion a.76 ev) Heavy flavour muons a forward rapidiy (.5 < y < 4) PRL 9 () ˆ pp reference measured a s =.76 ev ˆ Less suppression in peripheral collisions ˆ Suppression by a facor -4 for p > 5GeV/c in he % mos cenral collisions ALI PREL 97 ALICE Pb Pb s NN =.76 ev, µ ± HF in.5<y<4.4 R AA % 4 8%. Filled boxes: sysemaic uncerainy on normalizaion ALI DER 599 F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen / 9

19 Pb-Pb - R AA (p ) - D mesons ˆ pp reference: energy exrapolaion checked wih he direc measuremen in pp a s =.76 ev ˆ R AA s of D,D +,D + are in agreemen wihin uncerainies promp D R AA D + D y <.5 *+ D + Ds 7.5% cenraliy Pb Pb, =.76 ev s NN Filled markers : pp rescaled reference Open markers: pp p exrapolaed reference ˆ Srong suppression in a wide p range ˆ Firs measuremen of D + s in AA collisions ˆ he presen saisics does no allow us o conclude on he expeced enhancemen of D + s yield wih respec o non-srange D ALI PREL 94 mesons. F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen / 9

20 Pb-Pb - R AA (p ) comparison R AA ALI DER 685 Pb Pb, =.76 ev s NN + *+ Average D, D, D 7.5%, y <.5 ± Heavy flavor decay e %, η <.6 Heavy flavor decay µ ± %,.5<y<4. Empy boxes: sys. uncerainies Filled markers : pp rescaled reference Open markers: pp p exrapolaed or FONLL reference (GeV/c) p ˆ R AA Heavy flavours lepons similar in he mos cenral collisions despie differen rapidiies ˆ For proper comparison of D and lepon R AA he decay kinemaics should be considered F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 4 / 9

21 Pb-Pb - Charm vs. Beauy R AA..8 Pb Pb, s NN =.76 ev ALICE D meson R, 6<p < GeV/c, y <.5 AA Uncorrelaed sys. uncerainies Correlaed sys. uncerainies JHEP 9 ().6.4. Read from CMS PAS HIN 4 CMS Preliminary Non promp J/ψ R, 6.5<p < GeV/c y <. AA CMS Preliminary Non promp J/ψ sys. uncerainies N par ALI DER 448 ˆ R AA vs cenraliy for D mesons (ALICE) and J/ψ from B(CMS) ˆ Clear suppression in cenral collisions w.r.. peripheral ones ˆ Indicaions for R AA hierarchy, as expeced, (bu slighly differen kinemaical regions) R charm AA < R beauy AA F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 5 / 9

22 RAA ± RDAA /RπAA Pb-Pb - Charm vs. Ligh flavours.8 Pb-Pb, snn =.76 ev.6 + *+ Average D,D,D, y <.5, -7.5%.4 wih pp p -exrapolaed reference Charged paricles, η <.8, -% Charged pions, η <.8, -% WHDG rad+coll (Horowiz) AdS/CF Drag (Horowiz) Charged pions, η <.8 CUJE. (Buzzai) 5 Rad + dissoc (Viev) from arxiv:.6v.5.5 Rad (Viev).5.8 ALI DER 87 Pb-Pb, snn=.76 ev Cenraliy: -% Average D,D+,D*+, y < ALI PREL 4698 D mesons RAA shows similar rend as ligh hadrons in cenral collisions charm > R ligh : more saisics needed! Maybe hins of he hierarchy RAA AA F. Bossu Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 6 / 9

23 ± Pb-Pb - Azimuhal anisoropy v Heavy flavour decay e (promp D) v.4.. Pb Pb s NN =.76 ev Cenraliy 5% % Pb Pb, s NN =.76 ev, η < ALI PREL.. D, EP φ bins + D, EP φ bins *+ D, EP φ bins Empy box: sys. from daa Filled box: sys. from B feed down ALI PREL 8 v = ( + α)v e incl v e bkg π N in plane N ou of plane α v = R 4 N in plane + N ou of plane α = N HFe /N e bkg R : even plane resoluion ˆ Boh in he elecron channel and for D mesons v > a low-p (σ effec) F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 7 / 9

24 Pb-Pb - es bench for models Heavy flavour decay elecron R AA Pb Pb, s NN =.76 ev, %, η <.6 pp ref (scaled cross secion a 7 ev) pp ref (FONLL calculaion a.76 ev) BAMPS Rapp e al. POWLANG Coll.+LPM rad Heavy flavour decay elecron v. ALICE : Pb Pb, s NN =.76 ev, 4%, η < ALI PREL 55 promp D R AA ALI PREL *+ Average D,D,D Pb Pb, s NN =.76 ev y <.5 7.5% cenraliy Filled markers: pp rescaled reference Open markers: pp p exrapolaed reference WHDG rad+coll POWLANG (Beraudo e al.) BAMPS Rapp e al. BAMPS Rapp e al. POWLANG Coll.+LPM rad (promp D) v ALI PREL 754 D, EP φ bins Aichelin e al, Coll+LPM rad Beraudo e al, Langevin HL WHDG rad+coll Rapp e al. BAMPS ˆ Models reproduce reasonably well he R AA ˆ he simulaneous descripion of he R AA and he v behaviours is very difficul for models Pb Pb s NN =.76 ev Cenraliy 5% Empy box: sys. from daa Filled box: sys. from B feed down F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 8 / 9

25 Ouline Why heavy flavours HF wih he ALICE deecor HF in proon-proon collisions 4 HF in Pb-Pb collisions 5 Conclusions

26 Conclusions ALICE has measured open heavy flavours in pp and in Pb-Pb collisions. pp daa Measuremen of he producion cross secion a.76 and 7 ev of D mesons and HF elecrons a mid-rapidiy and HF muons a forward rapidiy pqcd models reproduce he measured cross secions wihin uncerainies Pb-Pb daa Nuclear modificaion facor (R AA ) shows srong suppression of HF muons, HF elecrons and D mesons in he mos cenral collisions Hins of hierarchy: D mesons are more suppressed of J/ψ B and hey seem o be less suppressed han ligh flavours Indicaion for non-zero v for D mesons and HF elecrons a low-p in semi-peripheral collisions Daa from he ongoing p-pb run will shed lighs on cold nuclear maer effecs for a beer inerpreaion of he Pb-Pb resuls F. Bossù Heavy flavour producion measuremen wih ALICE a he LHC Bormio, 5 Gen 9 / 9