DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 1 Future Perspectives for Charm Future Perspectives for Charm Physics Physics at Hadron Machines at Hadron Machines Sandro De Cecco Sandro De Cecco FNAL-PPD/CDF and INFN Roma 1 FNAL-PPD/CDF and INFN Roma 1
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Future Perspectives for Charm Physics at Hadron Machines
Future Perspectives for Charm Physics at Hadron Machines. Sandro De Cecco FNAL-PPD/CDF and INFN Roma 1. Outline:. Introduction on Heavy Flavour physics at hadron colliders. Charm production, charm as a probe for QCD Heavy quarks hadro-production in pp and NN interactions DD correlations - PowerPoint PPT Presentation
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DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 1
Future Perspectives for Future Perspectives for Charm PhysicsCharm Physics
at Hadron Machinesat Hadron Machines
Sandro De CeccoSandro De Cecco
FNAL-PPD/CDF and INFN Roma 1FNAL-PPD/CDF and INFN Roma 1
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 2
Outline:Outline:
• Introduction on Heavy Flavour physics at hadron colliders
• Charm input to CP violation picture– D0 mixing– Direct CPV in Charm decays– FCNC decays
• The Experimental “Charm” of Hadron Colliders
• Charm production, charm as a probe for QCD– Heavy quarks hadro-production in pp and NN interactions– DD correlations – Charmonium– Excited states, c-barions
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 3
Heavy-Quark production in hadron collisionsHeavy-Quark production in hadron collisions
Leading Order and Next to Leading Order
Gluon splitting
Flavor excitation
Flavor creation
g
g
gg
Q
Q
radiative corrections
B/D-Hadrons and/or b/c-jets are the observables rather than b/c-quark
Factorize physical observable into a calculable part and a non-calculable but universal piece
DF
cbpd
cXbqgggqqd
DBpd
DXBppd DBcbpp
TT
//
/
///
/
/
NLO QCD
Observed Proton structure
Fragmentation
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 4
Perturbative part: probability to find a hadron with fraction x’ of original parton momentum
Hadronization: non perturbative QCD, need models
Charm will have softer P-spectrum than b.
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 5
Charm and beauty at colliderCharm and beauty at collider
• Large cross section • Select triggering on:
– Semileptonic decays
• Trigger , e
– Hadronic decays (CDF-SVT)• One or more displaced tracks
i.e. large impact parameter√s (TeV)
0.001 0.01 0.1 1.0 10 102
1mb
1b
1nb
1pb
SppSTevatron
LHC(pp→X)(-)
(bb)
• Total inelastic x-sec ~100 mb = 103-104 x (cc/bb)
• x-sec is 105-106 larger than at e+e-
• Open spectrum of mesons and barions:•Bu , Bd , Bs , Bc , b , b…•D+, D0, Ds , c , c , c…
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 6
Selecting heavy flavour decaysSelecting heavy flavour decaysCLEO
CDF
To select charm and beautyIn hadronic environment:
High resolution tracking detector is mandatory
Only way to access hadronicdecays is to trigger on tracks
Primary Vertex
Secondary Vertex
Impact Parameter ( ~100m)
Lxy ~ 1 mm
B/D decay
Example: the CDF Secondary Vertex Trigger SVT
•Online (L2) selection of displaced tracks
based on Silicon detector hits.
D0 K
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 7
Charm program at hadronic machinesCharm program at hadronic machines
Tev
atro
nT
evat
ron
LH
LHCC
• First experiment doing high precision charm physics at collider, collecting huge yields in hadronic D modes• Many results already (in this talk) and more to come
• Nice charm physics program mainly on rare FCNC and LFV rare decays ( see Frank Lenher talk )• Relies on the presence of a muons to trigger charm
• Expect to be able to select clean charm signals thanks to fine tracking and PID• Will measure cc x-sections in pp, pN and NN collisions
• Thinking about having a dedicated D* charm trigger selecting huge and clean samples of hadronic D modes• Will definitely take over what CDF started in the search for CPV and mixing in charm
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 8
Open cc ProductionOpen cc Production
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 9
Prompt Charm Meson X-SectionPrompt Charm Meson X-SectionWith very early CDF data:With very early CDF data: 5.8 5.80.3pb0.3pb-1 -1 !!
• Measure prompt charm meson
production cross section
• Data collected by SVT trigger
from 2/2002-3/2002
• Measurement is not statistics limited
Large and clean signals:
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 10
Need to separate direct D and BD decay
• Prompt D point back to collision point
I.P.= 0
• Secondary D does not point back to PV
I.P. 0
Separating prompt from secondary CharmSeparating prompt from secondary Charm
Direct Charm Meson Fractions:Direct Charm Meson Fractions:
DD00: f: fDD=86.4±0.4±3.5=86.4±0.4±3.5%%
D*D*++: : ffDD=88.1±1.1±3.9%=88.1±1.1±3.9%
DD++: f: fDD=89.1±0.4±2.8%=89.1±0.4±2.8%
DD++ss: f: fDD=77.3±3.8±2.1%=77.3±3.8±2.1%
BD tail
Detector I.P. resolution shape measured
from data in K0s sample.
Most of reconstructed mesons are prompt
Separate prompt and secondary
charm based on their transverse
impact parameter distribution.
Prompt D Secondary D from B
Promptpeak
D impact parameter
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 11
• Issues are:- Low efficiency to have opposite charm in the acceptance- Backgrounds at low from BDDX decays.
• CDF already has clean samples of D*-D0, D*-D+ and D*Ds consisting of ~ few 100’s / few 1000’s events depending on the modes.•Expect to have correlation results based on 1 fb-1 of Luminosity
BDD BBbar
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 14
D mesons quenching reducedRatio D/hadrons (or D/0) enhanced and sensitive to medium properties
Charm as a probe in Pb-Pb collisionsCharm as a probe in Pb-Pb collisions
•Heavy quarks with momenta < 20–30 GeV/c v << c
• Gluon radiation is suppressed at angles < mQ/E
•“dead-cone” effect–Due to destructive interference (inside cone gluon with v=c would violate causality)
–Contributes to the harder fragmentation of heavy quarks and implies lower energy loss for heavy quarks relative to light quarks
Yu.L.Dokshitzer and D.E.Kharzeev, Phys. Lett. B519 (2001) 199 [arXiv:hep-ph/0106202].
A.Dainese nucl-ex/0311004
( from C. Fabjan )
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 15
Combine ALICE tracking + secondary vertex finding capabilities (sd0~60mm@1GeV/c pT) + large acceptance PID to detect processes as D0K-+ ~1 in acceptance / central event ~0.001/central event accepted after rec. and all cuts
HadronicHadronic charm selectioncharm selection
S/B+S ~ 37
S/B+S ~ 8for 1<pT<2 GeV/c(~12 if K ID required)
significance vs pT
Results for 107 PbPb ev. (~ 1/2 a run)
DIF 06 workshop, Frascati 01-03-2006 Sandro De Cecco - FNAL / INFN Roma 16