gines martinez-garcia * , sebastien gadrat *,# , and philippe crochet &
DESCRIPTION
Consequences of a c /D enhancement effect on the non-photonic electron nuclear modification factor in central heavy ion collisions at RHIC energies. Gines Martinez-Garcia * , Sebastien Gadrat *,# , and Philippe Crochet & (*) Subatech, Nantes, France (&) LPC Clermont Ferrand, France - PowerPoint PPT PresentationTRANSCRIPT
Consequences of a Consequences of a cc/D enhancement /D enhancement effect on the non-photonic electron effect on the non-photonic electron
nuclear modification factor in central nuclear modification factor in central heavy ion collisions at RHIC energiesheavy ion collisions at RHIC energiesGines Martinez-GarciaGines Martinez-Garcia**, Sebastien Gadrat, Sebastien Gadrat*,#*,#, and , and
Philippe CrochetPhilippe Crochet&&
(*) Subatech, Nantes, France(*) Subatech, Nantes, France(&) LPC Clermont Ferrand, France(&) LPC Clermont Ferrand, France(#) Now at LPSC, Grenoble, France(#) Now at LPSC, Grenoble, France
Hot Quarks 2008, Estes Park, Colorado, USA.More details in Physics Letter B663 (2008) 55.
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 22
Outline of the talkOutline of the talkPhysics Motivations:
– Non-photonic electron nuclear modification factor (RAA) at RHIC energies;
– Enhancement of baryon/meson ratio at RHIC energies;
Enhancement of the c/D ratio in HIC:– Model to compute the consequences on the
non-photonic electron RAA;Considering all ingredients:
c/D enhancement;– Quark energy loss;– Beauty contribution.
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 33
Non-photonic electron RNon-photonic electron RAAAA @ RHIC @ RHIC
Non-photonic electrons are assumed to arise from the semi-leptonic decay of charm and beauty hadrons;
Suppression increases with the centrality of the collision; Suppression similar to light hadron suppression at high pT; Radiative energy loss is not enough to explain the data.
PHENIX, PRL 172301 (2007) STAR, PRL 192301 (2007)
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 44
ee±± R RAAAA @ RHIC @ RHIC understood ? understood ?
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 55
Baryon/meson enhancement @ RHICBaryon/meson enhancement @ RHIC
STAR, nucl-ex/0703040STAR, nucl-ex/0701052 STAR, nucl-ex/0703033
already observed for light (u, d) and strange species ; the heavier the baryon, the higher in pT the maximum occurs (Ω/Φ) ;
quark coalescence models qualitatively describe the data (PRC65, PRL90, PRC68, PRC67, JPG30, PRC70).(PRC65, PRL90, PRC68, PRC67, JPG30, PRC70).
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 66
What about a What about a cc/D enhancement in HIC ?/D enhancement in HIC ?
D0, D0 D+, D- Ds+, Ds
- c+, c
-
BR (Xe)in %
6.71 0.29 17.2 1.9 8 +6-5 4.5 1.7
BR(c e anything) is smaller than any BR(D e anything)
A relative enhancement of the A relative enhancement of the cc/D would lead to a /D would lead to a « natural » single electrons suppression « natural » single electrons suppression withwith respect to respect to
p+p scaling !p+p scaling ! ee±± R RAAAA not exclusively sensitive to heavy quarks dE/dx ! not exclusively sensitive to heavy quarks dE/dx !
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 77
Proof in numbers…Proof in numbers…
ss
cccc
DDDDDDD NNNNNN
NN
NN
C00
,
eDe
eDe
D
DAA NN
NNCNNC
NNR
c
c
cc
cc
/1)/(1
)/(1
/1
,
,
ss
cccc
DDDDDDDDDDD
DeDe BRNNBRNNBRNN
BRNNNN
)/()/()/(
)/(/
0000 ,,
,,
%63.31%63.31
%3.71%3.71
C
CRAA
with C the c/D enhancement
factor
and
pp collisions @ 200 GeV :
1. Perfect binary scaling
2. Same D0,D+,Ds relative yields
RAA=0.90 (0.79) for c/D=0.35(0.84) C=5 (12)Yields (Pythia phenix settings) c/D ~ 0.073
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 88
Theoretical predictionsTheoretical predictionsV. Greco, Private communication &
Quenching Day, INFN (2005)
pT [GeV]
c/D
L. Cunqueiro & C. Pajares, Private communication & Eur. Phys J C53 585 (2008), arXiv:0712.0509v1 [hep-ph]
Enhancement of c/D is expected in HIC;
Maximum at 5-6 GeV/c; Existence of diquarks
correlations in the sQGP;
S. Yasui et al., arXiv:0803.1366v1 [nucl-th]S. H. Lee et al., arXiv:0709.3637v2 [nucl-th]
Recombination Percolation of strings
Diquark correlations
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 99
First study of this effect First study of this effect dondone by e by P. SorensenP. Sorensen and X. Dong and X. Dong
New RAA including c/D effect
Results:Results: enhancement effect for low pT: 2 ≾≾ pT ≾ 5≾ 5 GeV/c GeV/c; high value for the max c/D ratio required (~ 1.7 taken from the /Ks
0); suppression less than 20%.
Assumptions:Assumptions: use /Ks
0 measured shapes as a reference for c/D ones; the charm RAA is similar to light hadrons RAA.
~20%~20%
PRC74 024902 (2006), SQM06 & HQ06
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1010
A more detailed study of the charm A more detailed study of the charm enhanced B/M effect on the non-photonic Renhanced B/M effect on the non-photonic RAAAA
Sorensen and Sorensen and DongDong Our studyOur study
c/D shape in Au+Au as /Ks
0 Gaussian
c/D shape in p+p as /Ks0 from Pythia
Maximum of the c/D ratio
~ 1.7 (from the /Ks
0) for pT ~ 3 GeV/c
~ 1 for pT ~ 6 GeV/c
Energy loss From the scaling of the hadron shape
From S. Wicks et al., NPA 784(07)426
Beauty contribution No Yes
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1111
Pythia: p+p at 200 GeVPythia: p+p at 200 GeV
PHENIX data are well reproduced by Pythia (tuned according to PRL88 192303 (2002)) though Pythia spectrum slightly softer;
Decay electrons from c exhibit a softer spectrum: suppression of non-photonic electrons is further
enhanced !
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1212
cc/D enhancement hypothesis/D enhancement hypothesis
Evolution of the c/D (pT) assumed in the present work: Gaussian shape centred at 5 GeV, maximum at 0.9 and =2.9 GeV;
ppTT differential cross section is conserved ; differential cross section is conserved ;
dN/dpdN/dpTT with nuclear effects with nuclear effects RRAAAA = =
dN/dpdN/dpTT w/o any nuclear effect w/o any nuclear effect
Shape of the c/D (pT) enhancement
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1313
RRAAAA(p(pTT) from ) from cc/D enhancement/D enhancement
Natural suppression of the non-photonic electron till 40% in the pT region 2-4 GeV/c;
Suppression of 20% up to pT~9 GeV/c;
Attention ! Shadowing has not been taken into account but only relevant for pT < 2GeV/c.
Non-photonic electrons from charm
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1414
RRAAAA(p(pTT) with ) with cc/D enhancement and /D enhancement and charm energy losscharm energy loss
Collisional energy loss leads to a similar effect as c/D enhancement (light blue vs red);
Suppression 0.2 level, like light quarks seen for pT>3 GeV/c (blue);
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1515
Beauty contributionBeauty contribution
Not well known from experimental data;Large uncertainty from theory (mc, mb, Qr,
Qf);
T. Ullrich, Hard Probes 08
Crossing-points:4.5 and 10.5 GeV/c
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1616
RRAAAA (p (pTT) with all the effects) with all the effects
Additional suppression of the
non-photonic electrons of 10(25)%
due to c/D enhancement for a charm vs beauty
crossing point of 4.5 (10.5) GeV/c;
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1717
ConclusionsConclusionsEnhancement of the c/D ratio in HIC would lead to
a suppression of non-photonic electrons;
Assuming an enhancement similar to light hadrons with a maximum at pT=5 GeV, as expected from recombination models, the suppression of non-photonic electrons is increased by 10-25% in the pt range 4-9 GeV;
Direct measurement of open heavy flavour production are imperative before solid conclusion on the e± RAA can be drawn.
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1818
PRELIMINARYRun-4
Run-7
Rapp & van Hees, PRC 71, 034907 (2005)
minimum-bias
R. Averbeck, QM2008
PerspectivesPerspectives Role of the c/D
enhancement on the elliptic flow of non-photonic electron has to be understood …
Simulation in progress…
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 1919
Back upBack up
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 2020
Other effects related to the chemical Other effects related to the chemical composition of heavy flavoured composition of heavy flavoured
hadronhadron Enhancement of Ds meson production:
– BR in the semi-leptonic channel is not well known 8+6-5 %.
However, similar BR expected from the spectator model;– Small effect expected with this BR.
Enhancement of beauty B/M ratio:– The mass of the beauty quark being higher, beauty semi-
leptonic decays exhibit similar behaviour in beauty hadrons. Expected from the spectator model;
– Large enhancement is expected form diquarks correlations (factor 10);
S. H. Lee et al., arXiv:0709.3637v2
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 2121
Qualitative differences: light vs heavy Qualitative differences: light vs heavy quark recombinationquark recombination
1. For the same velocity, the pT of the heavy quark is larger, ~ mQ/mq factor:
– Recombination extend to higher pT;– Estimation pT
c~1 GeV x mc/mq = ~4 GeV (mc=1.25 GeV, mq=300 MeV);
2. Full pT : – Light: pT of the hadron (2 or 3) times the pT of the quarks; – Heavy: pT of the hadron slightly higher than the pT of the
heavy quark;3. The light (heavy) quark fragmentation time is long (short):
– 20, 1.5 & 0.4 fm/c for a 10 GeV/c , D & B meson (hep-ph/0611109)
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 2222
New parameterisationNew parameterisationGaussian shape centred at ~7 GeV, maximum of 0.9 and =2.9 GeV.
40%
Sébastien Gadrat, Hot Quarks 08Sébastien Gadrat, Hot Quarks 08 2323
New parameterisationNew parameterisation
10(25)% up to p10(25)% up to pTT ~9 GeV/c for a charm vs beauty crossing point at 4.5(10.5) ~9 GeV/c for a charm vs beauty crossing point at 4.5(10.5) GeV/c!GeV/c!