Quarkonium results in pp collisions from ALICE
Giuseppe E Bruno Università di Bari and INFN – Italy
for the ALICE collaboration
Quarkonia in Deconfined Matter
Acitrezza September 28-30 2011
Outline: introduction measurements in pp at √s=7 and 2.76 TeV
Integrated and differential cross sections for inclusive production
Multiplicity dependence at √s = 7 TeV J/ψ from B decays at √s = 7 TeV
outlook J/ψ polarisation and Upsilon measurements at
√s = 7 TeV
Introduction do I need to motivate the study of quarkonia within this
audience? J/ψ is “puzzling” in PbPb …
… and in fact we are at work at this meeting but J/ψ production is not that obvious in p-p collisions too
the production mechanisms in p-p collisions are not fully understood
but recent theoretical developments can account for the yields
Quarkonia in deconfined matter Giuseppe E. Bruno 2
J.P.Lansberg, PoS(ICHEP 2010), 206
Introduction
theoretical uncertainties are big NNLO* corrections in the CSM model give a good
description of the pt spectrum at intermediate pt. more observables from experiment should be
employed to constrain theory? Quarkonia in deconfined matter Giuseppe E. Bruno 3
S.J.Brodsky, J.P.Lansberg, PRD81 (2010) 051502
Introduction
Experimentally accessible information production rates (cross-sections)
inclusive and exclusive channels: direct, feed-down from beauty and higher charmonium states
differential vs. rapidity, transverse momentum
correlations J/ψ correlations with hadrons, leptons,
photons understand the production context
event multiplicity underlying event, jet fragmentation cone
polarization measurements Quarkonia in deconfined matter Giuseppe E. Bruno 4
Quarkonia with ALICE
Quarkonia can be measured in two ways: in the central barrel in the e+e- channel (|y|<0.9) in the forward spectrometer in the µ+µ- channel
(2.5<y<4) Quarkonia in deconfined matter Giuseppe E. Bruno 5
e+ e- µ+
µ-
Quarkonia at central rapidity
Quarkonia in deconfined matter Giuseppe E. Bruno 6
ICPAQGP Goa 2010 J. Schukraft PLC 20J. Schukraft
ITS
TPC
TRD
TOF
EMCAL
PHOS
HMPID
L3 Magnet
Key detectors: tracking
TPC,ITS PID
TPC, TOF, TRD, EMCAL
vertexing ITS
trigger EMCAL, TRD
0<φ<2π |ηe| < 0.9
e+ e-
Quarkonia at central rapidity
Quarkonia in deconfined matter Giuseppe E. Bruno 7
ICPAQGP Goa 2010 J. Schukraft PLC 20J. Schukraft
tracking PID
K. Aamodt et al. (ALICE Collaboration), Phys. Lett. B in press, arXiv:1105.0380
Quarkonia at forward rapidity
coverage: -4.0<η<-2.5 and pµ>4.0 GeV/c dipole magnet and 5 tracking chambers used for momentum
measurement muons are isolated using hadron absorbers it can run at higher luminosities compared to the slower
central rapidity detectors allows measurement of heavy quarkonia (J/ψ, ψ', Υ family)
Quarkonia in deconfined matter Giuseppe E. Bruno 8
0<φ<2π -4.0<ηµ<-2.5 pµ > 4 GeV/c
SPD
V0-A
V0-C
Event selection and data sample Triggers:
Minimum bias (MB) based on interaction trigger: SPD(pixels) or V0-A(scintillators) or V0-C(scintillators) At least one charged particle in 8 η units 87% efficient on σinel
Single muon trigger (pTthr=0.5 GeV/c):
Forward Muon in coincidence with MB read out MUON, SPD, ZDC, V0, FMD
Results presented today based on:
2010 pp run at 7 TeV 2011 pp run at 2.76 TeV
Quarkonia in deconfined matter Giuseppe E. Bruno 9
Energy J/ψ→µ+µ- J/ψ→e+e-
7.0 TeV 15.6 nb-1 5.6 nb-1
2.76 TeV 20.2 nb-1 1.1 nb-1
Kinematical and track quality cuts
J/ψ → e+ + e-
|ηe| < 0.9 pT
e> 1.0 GeV/c |yJ/ψ|<0.9 high quality ITS+TPC
tracks electron PID based on
TPC's dE/dx rejection of e from γ
conversions
Quarkonia in deconfined matter Giuseppe E. Bruno 10
J/ψ → µ+ + µ- pµ> 4.0 GeV/c 2.5<yJ/ψ<4.0 one muon trigger
matching 17.6<Rabs<89 cm
(radial track position at the end of the absorber)
Efficiency times acceptance
Quarkonia in deconfined matter Giuseppe E. Bruno 11
Acc
epta
nce
x ef
ficie
ncy
<Axε>=10%
<Axε>=33%
J/ψ → e+e- at 7 TeV, |y| < 0.9 J/ψ → µ+µ- at 2.76 TeV, 2.5<y <4
ALICE unique measurement at LHC
Signal extraction (7 TeV)
Quarkonia in deconfined matter Giuseppe E. Bruno 12
2C
ount
s pe
r 40
MeV
/c
20406080
100120140160180 OS
LS*1.23TrkRot
=7 TeVsALICE pp
)2 (GeV/ceem1.5 2 2.5 3 3.5 4 4.5 5
-200
20406080
100120140
OS-1.23*LS/dof=1.2)2MC (
Lint=5.6 nb-1 NJ/ψ=352±32 S/B=1.2 S/√(S+B)=14
signal extracted using bin counting, after bkg. subtraction
MC simulations describes well the signal shape
Fit with Crystall-Ball functions (J/ψ and ψ’) plus double exponential (bkg.) describes well the dimuon invariant mass spectra
Lint=7.9 nb-1 NJ/ψ=957±56 S/B≃2.6 mJ/ψ=3.118±0.005 GeV/c2
σJ /ψ=94±8 MeV/c2
K. Aamodt et al. (ALICE Collaboration), Phys. Lett. B in press, arXiv:1105.0380
Signal extraction (2.76 TeV)
Quarkonia in deconfined matter Giuseppe E. Bruno 13
Lint=1.1 nb-1 NJ/ψ=41±9
signal extracted using bin counting, after bkg. subtraction
MC simulations describes well the signal shape
Fit with Crystall-Ball functions (J/ψ and ψ’) plus double exponential (bkg.) describes well the dimuon invariant mass spectra
NJ/ψ=1287±48
Systematic uncertainties at √s=7 TeV
systematic error due to the unknown polarization estimated for extreme scenarios
major systematic errors come from signal extraction and reconstruction efficiency (for the di-electron channel)
similar uncertainties at √s=2.76 TeV Quarkonia in deconfined matter Giuseppe E. Bruno 14
e+e- µ+µ-
Signal extraction 8.5% 7.5%
Acceptance input 1.5% 5%
Trigger efficiency 0 4%
Reconstruction efficiency 11% 3%
Trigger enhancement - 3%
Luminosity 4% 5.5%
B.R. 1%
Polarization λ=-1 λ=1 λ=-1 λ=1
Collins-Soper +19% -13% +31% -15%
Helicity +21% -15% +22% -10%
Rapidity dependence of the inclusive cross-section
Cross section determination from van der Meer scan:
7 TeV σMB= 62.3±4.3 mb 2.76 TeV σMB= 54.2±3.8 mb
systematic uncertainties from
beam intensities (~4%)
Quarkonia in deconfined matter Giuseppe E. Bruno 15
d! (pp! J /" + X)dy
=NJ /"
corr
"y BR(J /"! l+l# )!MB
NMB
! J /" (| y |< 0.9) =10.7±1.0(stat)±1.6(syst)!2.3+1.6(syst pol) µb
! J /" (2.5< y < 4) = 6.31± 0.25(stat)± 0.76(syst)!1.96+0.95(syst pol) µb
7 TeV ALICE coll., PLB in press arXiv:1105.0380 (2011)
! J /" (| y |< 0.9) = 6.44±1.42(stat)± 0.88(syst)± 0.52(lumi)!1.42+0.64(syst pol) µb
! J /" (2.5< y < 4) = 3.46± 0.13(stat)± 0.32(syst)± 0.28(lumi)!1.11+0.55(syst pol) µb
2.76 TeV ALICE preliminary
K. Oyama et al. (ALICE Collaboration) arXiv:1107.0692
Rapidity dependence of the inclusive cross-section
Quarkonia in deconfined matter Giuseppe E. Bruno 16
Error bars are statistical and systematic errors (added in quadrature), excluding luminosity and polarization
Boxes are correlated error bars from luminosity
Comparison to CMS and LHCb shows agreement within error bars
ALICE: Phys. Lett. B in press ATLAS: Nucl. Phys. B850 (2011) 387 CMS Phys. J. C71, (2011) 1575 LHCb Eur. Phys. J. C71 (2011) 1645
y-5 -4 -3 -2 -1 0 1 2 3 4 5
b)µ
/dy
(J/
d0
1
2
3
4
5
6
7
8
9
10-e+ALICE, e-µ+µALICE,
CMSLHCb
open: reflected
=7 TeVspp
pT dependence of the inclusive cross-section
Quarkonia in deconfined matter Giuseppe E. Bruno 17
Error bars are statistical and systematic errors (added in quadrature), excluding luminosity and polarization
Boxes are correlated error bars from luminosity
Good agreement between ALICE and LHCb for 2.5<y<4.0
At mid-rapidity, ALICE and CMS+ATLAS cover the full pt range
ALICE: Phys. Lett. B in press ATLAS: Nucl. Phys. B850 (2011) 387 CMS Phys. J. C71, (2011) 1575 LHCb Eur. Phys. J. C71 (2011) 1645
(GeV/c)T
p0 2 4 6 8 10 12
b/G
eV/c
)µ
dy (
T /d
pJ/
2 d
-210
-110
1
, |y|<0.9-e+ALICE e, 2.5<y<4.0-µ+µALICE
CMS, |y|<1.2ATLAS, |y|<0.75LHCb, 2.5<y<4.0
=7 TeVspp
Comparisons to theoretical predictions
Quarkonia in deconfined matter Giuseppe E. Bruno 18
CS LO for direct J/ψ production reproduces rapidity dependence, despite large uncertainties
Inclusive J/ψ production at LHC energies, at low pT: J/ψ feed-down from higher charmonium states χc and ψ’ ~ 40% J/ψ from B-hadrons ~ 10% direct J/ψ ~ 50%
CS+CO NLO (NRQCD) reproduces well the spectra for pT > 3 GeV/c
Energy dependence
line = NLO cross section calculation for ccbar scaled to CDF data
Quarkonia in deconfined matter Giuseppe E. Bruno 19
CDF Collaboration PRD71 (2005) 032001 PHENIX Collaboration, PRL 98 (2007) 232002 M.Mangano et al., Nucl.Phys.B373 (1992) 295
J/ψ mean pT grows roughly as ln(s1/2)
Multiplicity dependence Charged particle multiplicity (dNch/dηmax ~30) reached in pp at 7 TeV is
comparable with semi-central CuCu collisions (50-55%) @ 200 GeV → “heavy-ion like” effects in p-p collisions at high multiplicity at LHC?
Quarkonia in deconfined matter Giuseppe E. Bruno 20
Almost linear increase of J/ψ yield with charged particle multiplicity Multi-parton interactions? Contributions from higher order
pQCD diagrams?
Different increase with respect to high pT muons (~80% from heavy flavour decays at 4 <pT< 8 GeV/c)
Prompt J/ψ and J/ψ from B hadrons
Component of J/ψ from B hadrons can be measured thanks to the excellent vertexing capabilities of the ITS
technique: simultaneous likelihood fit of invariant mass and
pseudo-proper decay length lJ/ψ
Quarkonia in deconfined matter Giuseppe E. Bruno 21
)/(/
/ ψψ
ψ JpmLlT
JxyJ ×=
)(sec ϕrrrL primxy
−=
|yJ/ψ|<0.9
Fraction of J/ψ from B
lowest pT at central rapidity at LHC energies
nicely complement the ATLAS and CMS measurements at y=0
Quarkonia in deconfined matter Giuseppe E. Bruno 22
Prompt and non-prompt J/ψ cross section, pt>2 GeV/c
inclusive cross-section, pt>2 GeV/c:
fraction of J/ψ from B hadrons:
Quarkonia in deconfined matter Giuseppe E. Bruno 23
d! inclusive pTJ /" > 2GeV / c, | yJ /" |< 0.9( )
dy= 3.76± 0.37(stat)± 0.49(syst)!0.59
+0.79(pol.) µb
±4%(lumi)
FB pTJ /! > 2GeV / c, | yJ /! |< 0.9( ) = 0.150± 0.059± 0.026(syst)+0.043(!HE=+1)!0.022(!CS=!1)
d! prompt pTJ /" > 2GeV c, | yJ /" |< 0.9( )
dy= 3.20± 0.38(stat)± 0.43(syst)
!0.58(!HE
= +1) + 0.82(!HE
= !1)
!0.29(!CS
= +1) + 0.53(!CS
= !1) µb
prompt cross-section, pt>2 GeV/c:
±4%(lumi)
Outlook: J/ψ polarisation (2.5<y<4)
key observable to study the production mechanism
determination of the full angular dependence of J/ψ (λθ, λφ, λθφ) is ongoing
preliminary results soon: expected error
on λθ ~ 0.15 for 3<pT<8 GeV/c
Quarkonia in deconfined matter Giuseppe E. Bruno 24
Outlook: upsilon family and more
2011 data will allow the measurement of Υ in the di-muon channel upsilon data now “on tape”
and results will be available soon
2011 and beyond: extension of PID and trigger
to EMCAL and TRD Υ family measurements at
both rapidities; J/ψ-hadron correlations and radiative decay from higher charmonium states (χc and ψ’) at mid-rapidity.
Quarkonia in deconfined matter Giuseppe E. Bruno 25
Conclusions J/ψ production in p+p collisions at √s = 2.76 and 7 TeV:
integrated and differential cross sections for inclusive production were presented. Results have been compared to other experiments, as well as to theoretical models on quarkonia production
results at 2.76 TeV serve also as reference to our PbPb measurements
linear dependence on charged particle multiplicity was observed
the fraction of J/ψ from B decays was measured at mid-rapidity
polarization analysis almost ready, results soon
upsilon measurement with 2011 data coming
Quarkonia in deconfined matter Giuseppe E. Bruno 26
Afterword
Quarkonia in deconfined matter Giuseppe E. Bruno 27
you may wonder what is the picture in my first slide
J/ψ ψ’
Υ
Minv(l+,l-)
dN/dM
Afterword
Quarkonia in deconfined matter Giuseppe E. Bruno 28
from the movie “La terra trema” by Luchino Visconti, based on the novel by Giovanni Verga “I Malavoglia” set in Acitrezza
Afterword
Quarkonia in deconfined matter Giuseppe E. Bruno 29
thanks for your patience
J/ψ ψ’
Υ
Minv(l+,l-)
dN/dM