r aa and r cp of single muons from heavy quark and vector boson decays at the lhc
DESCRIPTION
Workshop on Predictions for LHC, CERN, May 29 – June 2, 2007. R AA and R CP of single muons from heavy quark and vector boson decays at the LHC. Z.Conesa del Valle 1 , A.Dainese 2 , H.-T.Ding 3 , G.Martinez 1 , D.Zhou 3 1 Subatech Nantes, 2 INFN Legnaro, 3 CCNU Wuhan. - PowerPoint PPT PresentationTRANSCRIPT
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 1
RRAAAA and R and RCPCP of single muons of single muons
from heavy quark and vector boson decays from heavy quark and vector boson decays at the LHCat the LHC
Z.Conesa del ValleZ.Conesa del Valle11, , A.DaineseA.Dainese22, H.-T.Ding, H.-T.Ding33, ,
G.MartinezG.Martinez11, D.Zhou, D.Zhou33
11Subatech Nantes, Subatech Nantes, 22INFN Legnaro, INFN Legnaro, 33CCNU WuhanCCNU Wuhan
Workshop on Predictions for LHC, CERN, May 29 – June 2, 2007
thanks to N.Armesto, C.Salgado, U.Wiedemann
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 2
The Key Point:
’s from W as a medium-blind referencepQCD predicts b/W crossing at pt
muon ~ 30 GeV/c
from W should be unaffected by the medium
b-quark energy loss would shift crossing to lower pt
How would the muon RAA / RCP look like?
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 3
LHC Experiments: Muon Acceptance
ALICE muon spectrometer: -4 << -2.5 and pt >1 GeV/c
CMS, ATLAS: || < 2.5 and pt > 3.5 GeV/c
High pt reach in Pb-Pb: about 70-80 GeV/c
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 4
Baseline spectraHeavy quarks:
Quark-level baseline: c and b quark single-inclusive d2/dpTdy from MNR code (NLO pQCD)
parameters: mc=1.2 GeV, F=R=2mT,c, mb=4.75 GeV, F=R=mT,b, CTEQ4M PDFs (with EKS98 for Pb-Pb)
Peterson fragmentation function (with ymeson = yQ)
parameter from HERA-LHC Workshop proceedings (M.Corradi)
c=0.02, b=0.001 (from to LEP data)
Decay of meson to muon using spectator modele.g. kinematics for B from bc++
Vector bosons:PYTHIA (reproduces W cross section at Tevatron)
Cross section normalized to NLO results (Frixione-Mangano, Vogt)more details in: Z.Conesa del Valle et al. ALICE-INT-2006-021
MNR code: Mangano, Nason, Ridolfi, NPB373 (1992) 295
HERA-LHC Proceedings, CERN/LHCC 2005-014, hep-ph/0601164Frixione, Mangano, hep-ph/0405130; Vogt, hep-ph/0011242
Eskola, Kolhinen, Salgado, EPJC 9 (1999) 61
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 5
Total single-muon spectrum in Pb-Pbwithout E loss
ALICE muon spectrometer acc.:-4 < < -2.5, pt > 1 GeV, p > 4 GeV
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 6
Effect of shadowing (EKS98) in Pb-Pb
Wbeautycharmtotal
-4 < < -2.5
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 7
Effect of shadowing (EKS98) in Pb-Pb
. :
2 :
21
21
constMQsxxWqq
pQsxxbbgg
WNN
tNN
Wbeautycharmtotal
just an indication (PYTHIA LO):
-4 < < -2.5
-4 < < -2.5 -4 < < -2.5
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 8
Effect of shadowing (EKS98) in Pb-Pb
val. qsea qgluongluon
EKS98 val. q EKS98 sea q
W1.0*0.85=0.85
Wbeautycharmtotal
ALICE muon spectrometer-4 < < -2.5
-4 < < -2.5
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 9
Effect of shadowing (EKS98) in Pb-Pb
val. qsea qgluongluon
bEKS98 gluonEKS98 gluon0.95*1.05=1
Wbeautycharmtotal
ALICE muon spectrometer-4 < < -2.5 -4 < < -2.5
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 10
Heavy Quark Radiative E LossMass-dependent BDMPS quenching weights
Glauber collision geometry à la PQM
Transport coefficient for a static medium: /fmGeV 10025ˆ 2q
Armesto, Dainese, Salgado, Wiedemann, PRD 71 (2005) 054027.
EKRT Saturation modelEskola, Kajantie, Ruuskanen, Tuominen, NPB 570 (2000) 379.
C.Salgado
C.Loizides
/fmGeV 144ˆ 2RHICq
/fmGeV 10025ˆ 2LHCq
7 (corresponds todNch/dy ~ 3000)
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 11
E loss for c and b VS rapidityCalculation of radiated energy: compute E using Lt; quench pt; keep y constant.
Decrease of medium density at forward rapidity should be accounted for
Assumed , i.e.
using LHC multiplicity as predicted by D.Kharzeev, E.Levin, M.Nardi, hep-ph/0408050
(gives moderate density change for || < 4) pt
y
Lt
d
dNq ch)(ˆ
0*
)0(ˆ*)(ˆ
d
dN
d
dNqq chch
-15%
negligible effect on muon suppression for || < 4
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 12
Effect of E loss in Pb-Pb 0-10%
Crossing point shifts down by 5-7 GeV/c RAA increases from 0.3 to 0.8
RCP (0-10%)/(40-70%)increases from 0.4 to 0.9
Similar results in -4 < < -2.5
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 13
Effect of E loss in Pb-Pb 0-10%- b mass effect -
thin: no mass effectthick: mass effect
thin: no mass effectthick: mass effect
RAA RCP
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 14
Summary
At LHC, high pt muon spectrum will be one of the first measurements sensitive to b quark energy loss
Crossing point of b and W muons shifts down by 5-7 GeV/c
RAA rapidly increases from 0.3 to 0.8 between 20 (b-dominated) and 40 GeV/c (W-dominated)
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EXTRA SLIDES
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 16
Baseline: from c and b, no E loss
(from Z.Conesa)
(from Z.Conesa)
BD can be neglected:
MNR+Peterson+spectator model decay VS PYTHIA (ALICE tune)
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 17
from b with E loss:effect of mass
Effect of b-quark mass for ptmuon < 20-30 GeV/c
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 18
from b with E loss:effect of dN/d scaling for qhat
In this model, the effect of density decrease at forward y is negligiblewithin the MUON spectrometer acceptance
LHC Predictions Workshop, CERN, 01.06.2007 Andrea Dainese 19
Effect of E loss in Pb-Pb- ALICE muon spectrometer -
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