29 september 2006cdf charm studies at beauty 2006, burkard c. reisert, fnal1 charm studies at cdf...

29 September 2006CDF Charm Studies at Beauty 2006, Burkard C. Reisert, FNAL 1

Charm Studies at CDFCharm Studies at CDF Burkard C. ReisertBurkard C. Reisert

for the CDF Collaborationfor the CDF Collaboration

• Charm Meson Pair Production

• Studies of Charmonium Production

- J/and ' polarization

- Relativec1, c2 Production

Picture of

FNALor

Oxford


Motivation:Inclusive Charm Meson Cross Sections

D0

Kniehl et al., hep-ph/0508129

The measurement of inclusive charm meson\cross sections (D0, D*±, D+, Ds

+) was one of the first CDF Run II results

- up to a factor 2 higher than expected- progress in theory reduced deviation - still on the high side - measurement systematically limited

(L=5.8 pb-1)CDF Run II (L=5.8 pb-1)CDF Run II (L=5.8 pb-1)

FONLL

Cacciari et al., JHEP, 05:00, 1998CDF Collab., PRL 241804


Heavy Quark Production: Leading Order Picture

• Second charm particle in the event gives access to the underlying production mechanism

• Study fully reconstructed prompt charm meson pairs allows for acceptance and efficiency correction

large 0 °

large

180 °

PS = Parton Shower


Charm Meson Pair Reconstruction

Simple experimental approach

Find triggered charm meson D0, D+, D*, Ds

+,

Look for second charm meson probe D*+

Take advantage of inclusive measurement from a short well controlled running period:

Measure of pair cross section relative to inclusive cross section, systematic uncertainties largely cancel over the entire CDF Run II

PrimaryVertex


Prompt Charm Production Cross Sections

• Inclusive production (already measured by CDF):

• Pair production:

• Relative pair Cross section:

• uses

1 d

i DDpi

i iyT

N fd

dP t B

L

1 2

1,2

2

1 1 2d

D D ij DDij P

i j ijyT T

N fd

dP dP t B B

L

Ni: Number of observed charm mesons in ith PT bin

Nij: Number of observed charm meson pairs with D1 in ith PT bin and D2 in jth PT bin

fPD: fraction of prompt D mesons

fPDD: fraction of prompt pairs

i: trigger and reconstruction efficiency

ij: pair trigger and reconstruction efficiency

j: probe-side reconstruction efficiency

dt: integrated luminosity

B: branching fraction e.g. D0K2

1DDij ijP

i i D jP

fN

N f B

ij i j (MC study: valid better than 2.5%)


Inclusive triggered charm mesonsInclusive triggered charm mesons


Number of D0TrigD*±

Probe Pairs

2dim SB-subtraction by weighting eventsIn mass plane of Trigger D and soft tagged Probe D0


Ds+D*-

D*+D*-

D+D*-


Charm Meson Pairs vs. Charm Meson Pairs vs. (Raw (Raw Yields)Yields)

Uncorrected for efficiency () and secondary (fb) detector level distributionsfully reconstructed decays of both D correct for (simulation verified on data)

D0D*-

D0D*-

D+D*-

D0D*-


Extraction of Prompt D Production

● Extract prompt/secondary fractions from Ip of probe side D0: fbb =34%

● Cross checks : Ip, Lxy of trigger/probe D and DD*- pairSecondary D

Prompt D

PV = Primary Vertex

Ip


Measurement of Charm Meson Pair Cross Section

Pr

Pr Probe

DDij DDD

i D j

fN

N f Br

published CDF measurementsof inclusive cross sections

branching fraction from PDG

Efficiency for fullyreconstructed Probe side D*+

Inclusive Charm MesonYields and prompt Fractions

DD Pair yields and Prompt fraction


D0D*- Pair Cross Section binned in PT(Trig)

Error:statsys(fb)

CommonSyst. Error: ~15%


D0D*- Cross Section

● Normalization of D0D*- cross section in Pythia is about right,● Gluon Splitting as important as Flavour Creation● Pythia under estimates GS (over estimates FC)


Error:statsys(fb)

CommonSyst. Error: ~19%

Significant shape discrepancy Consistent for D0D*- and D+D*-

D+D*- Pair Cross Section binned in PT(Trig)


Charmonium Production


Color Singlet & Color Octet models

Color Singlet Model:● cc pair is “bleached” by radiating

off a hard gluon● Underestimates J/ (1/10) and

’ (1/50) production● Feed down from cj dominates

(>90%) J/ production (CDF Run I finds 30%)

● PT spectrum does not match data

p p

pp

J/ J/

hard g

soft g

c

cc

c

Non relativistic QCD introducesColor Octet Mechanism:● Soft gluon radiation● Adjustable hadronization

parameter allows to match the observed PT spectra and production cross sections

● Predicts transverse polarization for J/deviates from data


“Pomeronic Idea”

J/

p

p

PP

PP

J/

p

p

Pomeron picture pQCD Recent idea by V.A. Khoze, A.D. Martin, M.G. Ryskin and W.J. Sterling hep-ph/0410020

Fusion of a symmetric colour octet state and a gluon

● Cross sections calculated in LO pQCD consistent with data

● PT spectra match data● Predicts longitudinal

polarisation of J/increasing with pT

Emission of omerons omerons have vacuum Quantum numbers JP = 00

PP PP


Polarization of J/

2 **

1 coscos

with ( 1 1)

d

d

* angle between + in J/ rest frame and J/ in lab frame

polarization parameter

=0 all 3 helicity states are equally populated

MC polarization templates

(trigger efficiency from data)


J/ Yields and Separation of Prompt and Secondary J/

0 0

2 2

0 0

d d

d dS

Use combinedimpact parametersignificance to

separate prompt S≤8 and secondary S>16

J/ selection Central: |y|<0.65<PT<30GeV/c


Polarization of J/ Mesons

Polarization of J/ from B decays ● independent of PT● B = -0.066±0.050● Consistent with BaBar

(B = -0.129±0.009)CDF result includes Bs and B baryons

Polarization of prompt J/ ● Corrected for residual

secondary J● <0: longitudinal polarization


’ Polarization

● Same theoretical framework applies to prompt ’ and J/production

● no contribution from feed down from higher states therefore ’ is a cleaner system to test direct charmonium production

● ’ uses analysis approach as just described for J/


’ Polarization Results

Polarization of prompt ’● Longitudinal polarization

at high pT, just as for J/

Polarization in B decays ● First measurement of B for ’● B = 0.28±0.27± 0.03(consistent with J/ within stat.)


cJ Production

● Models of prompt charmonium production in hadron collisions always contain significant cJ

contributions

● The measurement of (c2)/ (c1) has been performed at several energies and beam types over the years. Best measurements have ~100 events, 30% statistical

uncertainty on the cross section ratio. Results like 1.0±0.3 are consistent with most models.


Measurement of (c2)/(c1)

● Measurement of properties of cJ

production has always been an experimental challenge

● Low energy photon from cJJ/ is difficult to measure (~400 MeV in cJ

rest frame)

● Calorimeter measurements have good efficiency but poor resolution and high background in a hadron collider environment

● Conversion measurement - good resolution- poor efficiency

(now compensated L=1fb-1)

cJ

J/

ee


cJ Data Set

Here we reconstruct:cJJ/, J/+-, e+e-

● J/ selection as polarization analysis● Photon conversion gives excellent

energy (mass) resolution.● Prompt and B-decays are easily

separated

Simultaneous fit to the mass and flightdistance distributions is used to extract the relative yields for both prompt cJ and cJ from B decays


Results on c1)/c2)

• New level of precision for measurement of c1)/c2)

• Should provide nice constraint on models of production mechanisms

• Result for prompt cJ:

2

1

( ) 0.70 0.04( .) 0.03( .) 0.06( . .)c

c

stat syst B F

for 4 < pT(cJ) < 20 GeV/c

● Color Octet predicts 5/3 (counting of Spin states)


Conclusion

The unprecedented integrated luminosity delivered by the Tevatron in conjunction with CDF’s high bandwidth trigger allows us to perform Charm studies we did not anticipate. New “Charming” results:● First measurement of charm meson pair cross section

in an hadron collider environment probes open charm production: gluon splitting underestimated

● Polarization measurements of J/ and ’ instigates new theory approach to charmonium production

● New level of precision for measurement of (c1)/(c2) provides new trial to models of charmonium production

Charm Physics at the Tevatron has its beauty


Acknowledgements

Contact persons for the presented CDF analyses:

● Charm meson pair cross SectionsBurkard Reisert, [email protected]

● J/ and ’ polarizationMin-Jeong Kim [email protected] Chung [email protected]

● Relative c1 c2 productionPatrick Lukens [email protected]


Backup slides

● Tevatron, CDF & Trigger


Heavy Quark Production in Higher Orders

• Example Feynman Diagrams

• Calculations with massive quarks– incoming charm (?)

– charm in final

state parton shower (?)

• All shown example graphs can be interpreted as higher order flavor creation

Q

g

g

g

g

g

g

g

g

g

g

g

g

g

g

g

g

g

g

g

g

Q

Q

Q

QQ

Q

Q

Q

Q

QQ

Q Q

QQ

Flavor Creation (a2s) Flavor Creation (a2

s)

Gluon Splitting (a3s)Flavor Excitation (a3

s)

Gluon Radiation (a3s)

Interference Term (a4s) Interference Term (a4

s)

Gluon Radiation (a3s)


TevatronTevatron

Run II Physics Goals:● Properties of top quark● Precision Electroweak Physics● CKM, Bs Mixing● Searches for new phenomena● Tests of QCD

New world record

ISR @ √s=62 GeV


Collider Detector at FermilabCollider Detector at Fermilab

Silicon Microstrip Tracker

Time-of-Flight

Drift Chamber

Plug Calorimeter Muon

Muon System

Solenoid

Central Calorimeter

Fwd Calorimeter

|| to 5.5

Scint based || to 3.6

1.0<||<2.0

Old

New

PartiallyNew


CDF Trigger & DAQ System

CDF Detector

L1 trigger

L2 trigger

L3 farm

disk/tape

42 L1buffers

4 L2buffers

1.7 MHz crossing rate

25 kHz L1 accept

500 Hz L2 accept

100 Hz L3 accept

Hardware tracking for pT 1.5 GeV

Refined Muon-track matching

Electron-track matching

Missing ET, sum-ET

Silicon tracking

Dedicatedhardware

Hardware +CPU

Linux farm(>200 CPUs)

Jet finding

Full event reconstruction

Refined electron/photon finding

The trigger is the key to heavyflavour physics at hadron colliders

Muon-track matching


Triggers forBeauty & Charm Physics

Di-Muon (J/)PT() > 1.5 GeV

J/(2S) modesDown to low PT(J/)

(~ 0 GeV)

Two Track TriggerPT(trk)>2 GeV

IP(trk) >100 m

Fully hadronic modes

Displaced track(s)+ lepton (e,)IP(trk)>120 m

PT(lepton) >4GeV

Semileptonic modes

• (2s), X(3872) J/(quarkonia)

• BsJ/, Bu,d J/Ks(*)

bJ(masses, lifetimes, mixing calibration)

• Bs,d(rare decays)

• Bc(lifetime BJ/lX, mass B J/)

• 2-body charmless decays (B0,Bs,b)

• Bs mixing (hadronic)

• Charm physics

- inclusive cross sections

- D0

• Heavy quark production

•Bs mixing (semileptonic)

•Tagging, lifetime

PrimaryVertex

SecondaryVertex

Decay LengthLxy

d=impact parameter

29 september 2006cdf charm studies at beauty 2006, burkard c. reisert, fnal1 charm studies at cdf...

Documents

trig d

fnal9 d s d

charm meson probe d

d correct

data d

cdf charm studies

triggered charm meson

cdf burkard