Heavy Flavor Production in Hadron Collisions (with a few leptons

1
Heavy Flavor Productionin Hadron
Collisions(with a few leptons photons thrown
in)

• Harold Evans
• Columbia University
• XXIV Physics in CollisionBoston, MA June 28,
  2004

2
Why Study QCD at All ?

• QCD is the Theory of the Strong Force
• So why arent we still at lunch ?
• Because of non-perturbative effects we cant make
  accurate predictions using QCD for a large range
  of observables
• This is Bad
• on an intellectual level
• because QCD procs are intimately entwined with
  other SM effects
• backgrounds, corrections to EW observables,
• Fortunately, QCD can be studied using many
  processes
• this talk will review how heavy flavor production
  helps

3
Whats so Great about Q Production ?

• Arbitrary Definitions Heavy Flavor c and b
• Obese Flavor t

see talk by Andy Hocker
4
What Ill Talk About / What Ill Skip
Problem Too many New Results !

• Concentrate on
• Hera, Tevatron, some Fixed Target
• very recent results
• areas where our understanding has changed
  substantially
• surprises
• Tragically Ignore
• nearly all ee- results
• feeble excuseno hadrons in initial state
• cursory view of fixed target
• mainly as it overlaps collider
• detailed survey of advances in theory

• Focus of Talk
• previous status of
• what we (thought) understood
• problems
• how this has changed recently
• improvements in understanding
• remaining problems
• where we go from here
• how new exps can help
• Outline
• Open b c Production
• Heavy Quarkonia
• New Resonances
• The Future

My Apologies if Ive Left Out your Favorite Topic
5
Acknowledgements Warnings

• Many Thanks to
• H.Cheung, M.Corradi, R.Galik, V.Jain, R.Jesik,
  G.Landsberg, M.Leitch, M.zur Nedden, P.Newman,
  C.Paus, J.Russ, L.Silvestris, M.Smizanska,
  K.Stenson, A.Zieminski, D.Zieminska, A.Zoccoli
• all those whose work I am presenting
• and of course, the conference organizers !
• Some Warnings
• I blithely combine results and make Data vs
  Theory comps
• these always assume no error correlations
• often use spread in theoretical predictions as
  error
• This is not the fault of those listed above

6
Heavy Quarks in the Wild
Exp. or Facility Beams (GeV) vs / NGeV Runs Recorded Data
FOCUS/E831 ?(175) BeO 18 96-97 7B ints
NuSea/E866 P(800) Cu 38 96-97 9M J/?
SELEX/E781 ?-,?-(600) C,Cu 33 96-97 15B ints
Hera-B P(920) C,Al,Ti,W 41 00,02-03 308K J/?
HERA I e(27.6) p(820,920) 300/318 93-00 130 pb-1
HERA II e(27.6) p(920) 318 03-04 70 pb-1
Tevatron I 1800 92-96 125 pb-1
Tevatron II 1960 02-04 400 pb-1
LEP e(45,100) e-(45,100) 90210 89-00 3.6M bb
7
Issues in b c Production

• NLO terms are important, NNLO impossible
• vary factorization, renormalization scales ? est
  NNLO effects
• Q mass definition / uncertainties
• generally mb 4.55.0 GeV mc 1.21.8
  GeV
• Large log(pT/m) resummation important at
  Tevatron, LHC
• must be matched to NLO calc (e.g. FONLL)
• Soft gluon corrections near threshold important
  at Fixed Target
• require some NNLO NNNLL
• Non-Perturbative parts
• Structure Functions Fragmentation Functions
  consistent w/ perturb calc.

Perturbative Worries
8
some History b,c Cross-Sections

• b Production vs NLO QCD
• shape in good agreement
• norm off by factors of 23 (nearly w/in exp
  theory errors)

• c Production vs NLO QCD
• agreement much better

9
New b,c-Production Results Reported
b Production b Production b Production
CDF b-Hadron inclusive cross-section in Run II using Hb?J/?X Preliminary (2003)
Hera-B b b-bar production cross-section in pN collisions Preliminary (2004)
H1 Beauty photoproduction using semi-muonic decays Preliminary (2003)
ZEUS Beauty photoproduction using muon dijet events hep-ex/0312057
H1 Beauty production in DIS Preliminary (2004)
H1 Charm beauty production in DIS at high Q2 Preliminary (2004)
ZEUS Beauty production in DIS hep-ex/0405069
c Production c Production c Production
CDF Prompt charm production cross-section at ?s 1.96 TeV PRL 91, 241804 (2003)
Hera-B Open charm production using D-mesons Preliminary (2004)
FOCUS Charm anticharm baryon production asymmetries PLB 581, 39 (2004)
H1 Inclusive D dijet production in DIS Preliminary (2003)
ZEUS D production in DIS PRD 69, 0120004 (2004)
H1 Photoproduction of D Preliminary (2003)
ZEUS Measurement of D photoproduction Preliminary (2002)
ZEUS Charm jet photoproduction Preliminary (2004)
10
The Road to Enlightenment ?

• B-hadrons instead of b-quarks
• FONLL CalculationCacciari, Greco, Nason 1998
• full, massive NLO calc.
• NLL resum of log(pT/m)

• Consist. treatment of fragm.Binnewies, Kniehl,
  Kramer 1998Cacciari, Nason 2002
• FONLL framework used to extract FF from ee- data
• Tevatron data sensitive to N35 moments of FF?
  params of FF change

11
CDF Hb ? J/? Cross Section

• Run II J/? ? ? ?- Data 37 pb-1
• Feb-Sep 2002
• Hb ? J/? fract. vs. PT(J/ ?)
• pos. of J/? vtx w.r.t. prim vtx
• 1.25 lt PT(J/?) lt 17 GeV
• d?(Hb)/dPT(Hb) from ?incl(J/?)
• unfold PT(Hb) from PT(J/?)
• to PT(Hb) 0
• Main Systematics
• acc., ?incl(J/?), vtx res.

• Total x-section corr. to quark level
• Good agreement w/ FONLL pred
• large error dominated by ?R,F dependence

10 of current data
y lt 0.6
syst. limited
Cacciari,Frixione,Mangano,Nason,Ridolfi
hep-ph/0312132
12
Other Possible Explanations
From good Old FriendsIntrinsic KT
To exotic New OnesLight gluinos

• DØ Data 2000 1-? 2-?

Shabelski, Shuvaev hep-ph/0406157
Berger, Harris, Kaplan, Sullivan, Tait, Wagner
2001
13
Open Beauty at Hera-B
Use displaced vertices to extract b-comp from J/?
(ee,??) sample
Run prompt J/?s bs Total x-sectnb/nucleon
00 ee 5.7K 8.6 32 14-12 6-7
?? 2.9K 1.9 32 14-12 6-7
02/03 ee 150K 31 12.3 3.5-3.2 (stat)
?? 170K 38 12.3 3.5-3.2 (stat)
prelim 35 of 02/03 data prelim 35 of 02/03 data prelim 35 of 02/03 data prelim 35 of 02/03 data
E771
Hera-B 00
E789

• Soft g corrs important near thresh
• new calculation NNLO soft-g NNNLL terms
• kinematics scale dep. reduced

N2LO-N2LL N2LO-N3LL? exact NLO
Kidonakis, Vogt hep-ph/0405212
m4.55 Gev
14
Beauty in ep Collisions
H1 ZEUS look for bs in ? jet(s) data

• H1 finds bs with
• Ptrel ?
• In
• DIS Q2 gt 1 GeV2
• PhP Q2 lt 1 GeV2

• ZEUS uses
• Ptrel
• In
• DIS
• PhP

15
b Photoproduction
Years Lumi pb-1 Sample evts Main Systematics
H1 (prelim) 99-00 48 446 36 ?-ID, trk vtx res.
ZEUS 96-00 110 820 62 ?-ID, PTrel, dijet sel.
syst. limited
Data-NLO agreement quite good but problems atlow
PT low x ?
16
b Deep Inelastic Scattering
Years Lumi pb-1 Sample evts Main Systematics
H1 (prelim) 99-00 50 243 29 ?-ID, trk res., phys. model
ZEUS 98-00 72 284 36 sel. cuts, ?-ID, signal extr.
ZEUS
probs at low Q2 x ?
17
Measuring F2cc F2bb at H1 (prelim)

• Intrinsic c and b in proton
• Inclusive Data Sample
• track ?-tagging
• high Q2 (gt 150 GeV2)
• X-Sect (Q2gt150 GeV2, 0.1ltylt0.7)

• Good agreement w/ F2cc from D
• Extend b-prod data to higher Q2

18
b-Production Scorecard

• Improved Data-Theory at CDF
• use B-hadrons 20
• FONLL calc 20
• consist fragm 20
• fragm params 20
• Agreement slightly worse at HERA
• but no huge probs
• Experiments largely syst dominated
• scale w/ stats ?
• Theory errs gt Exp errs
• exp constrains theory

19
Charm Production at CDF

• Run II J/? ? ? ?- Data
• Feb-Mar 2002 5.8 pb-1
• uses SVT 2-Track-Trigger
• Separate prompt-c from b?c
• Imp. par. of c-candidate
• Main Systematics
• 1-track eff., 2-track eff. corrs

PT gt X cands ?(D, PTgtX, ylt1) ?b
D0 5.5 36804 13.3 0.2 1.5
D 6.0 5515 5.2 0.1 0.8
D 6.0 28361 4.3 0.1 0.7
Ds 8.0 851 0.75 0.05 0.22

• Reasonable agreement w/ FONLL theoryCacciari,
  Nason JHEP 0309, 006 (2003)Kniehl, Kramer,
  Potter NPB 597, 337 (2001)

Ds ? ? ?
D0 ? K- ?
D ? D0 ?
D ? K- ? ?
syst. limited
3 of curr data
20
Open Charm at Hera-B

• 2002/03 Min Bias data 210M evts
• D/D0 x-section ratio expect 1/3
• diff. largely due to feed-down from D
• BR(D0 ? D0 X) 100
• BR(D ? D0 X) 70
• prev. meass not entirely compatible(with large
  uncertainties)
• new Hera-B measD/D0 0.54 0.11 0.14

N ?(-0.1ltxFlt0.05) ?b/N ?(all xF)?b/N
D ? K- ? ? 9812 11.5 1.7 2.2 30.2 4.5 5.8
D0 ? K- ? 18920 20.4 3.2 3.6 56.3 8.5 9.5
D ? D0 ? 438
consist w/ prev data
Hera-B D/D0
21
Charm Baryon Asymmetries at FOCUS

• Perturb. QCD ? small charm asym in Fixed Target
  exps
• Leading Particle effects can change this

A(?c)
6.203
Poor Agreementdata vs PYTHIA
FOCUS 2003
Leading particle common valence qs w/
target/projectile
?c E791
focus Meas Asymmetry PYTHIA
?c 0.1110.0180.012 0.073
?c 0.1360.0730.036 0.126
?c0 0.0050.0890.024 0.128
?c 0.1810.1050.033 0.133
?c0 0.2980.1650.023 0.132
?c2625 -.0750.0870.021 n/a

• Heavy-Q Recomb.
• better descrip.of prev. data
• also describes A(D)

Braaten, Kusunoki, Jia, Mehen hep-ph/0304280
?c SELEX
22
D Production in DIS
Years Lumi pb-1 Sample evts Main Systematics
H1 (prelim) 99-00 47 2604 77 track reco. eff.
ZEUS 98-00 82 5545 129 D reco, accept.
Open Charm contrib to F2 useful to constrain
gluon density in proton !
syst. limited
good agreement w/ NLO QCD
23
D (jets) Photoproduction
Years Lumi pb-1 Sample evts Main Systematics
H1 prelim 99-00 49 1117 76 track reco
ZEUS prelim 98-00 79 10350 190 signal extr., MC model

• Jet X-Sect ZEUS 99-00
• less sens. to hadr. effects
• extend further forward
• mild discreps remain

• Data NLO Discrepancies
• mid-Pt high ?

H1 (prelim) 99-00
ZEUS (prelim) 98-00
ZEUS (prelim) 99-00
24
c-Production Scorecard

• FONLL calc agrees very well with CDF data
• but theory errs large
• Latest HERA meass agree with NLO
• no improve w/ FONLL
• Experiments largely syst dominated
• scale w/ stats ?
• Theory errs gt Exp errs
• especially for newest calcs (CDF)

• n.b. PYTHIA ? poor descrip of FOCUS Asym
• Q-recombination models much better

25
We should Understand J/? ?

• quarkonium meson retains quantum numbers of hard
  scatter
• for any S/color/L state n
• (non-perturb) NRQCD matrix elements ltOH(n)gt from
  fits to data

ep collisions
hadron-hadron collisions
Other production mechanisms also possible
26
The J/? Production Crisis
CDF 1997the CSM doesnt work !
COM to the Rescue !
Braaten, Kniehl, Lee PRD 62, 094005 (2000)and
Tevatron Run II B Working Group
DIS H1 2002
PhP H1,ZEUS 2003
maybe in ep too ?
So we all feel fairly Smug but things get
confusing !
27
COM Means Polarization
CDF sees no Polarization in J/? or ?(2S)(largely
from data at high PT)
Fixed Target meass also lower than COM
Exp Int E GeV Pol
COM 0.35 0.65
E672/E706 ?- Be 515 ?0.010.08
p Be 530 0.010.15
p Be 800 ?0.110.15
E711 p Si 800 ?0.090.12
WA92 ?- Cu 350 ?0.010.19
J/?
CDF 2000
Caution most exp results include large contrib
from decay J/?s, which have NO polarization
?(2S)

• situation even less clear
• CDF consist w/ NRQCD (large errors)
• NuSea finds pol ?(1S) 0 pol ?(2S,3S) 1

CDF 2002
28
New Quarkonium Results Reported
NuSea J/? polarization in 800 GeV p-Cu interactions PRL 91, 211801 (2003)
ZEUS DIS production of J/? Preliminary (2003)
ZEUS J/? helicity in DIS Preliminary (2003)
CDF Inclusive J/? cross-section (start point of Hb result) Preliminary (2003)
see talk by Rich Galikfor more on Quarkonia
29
J/? Polarization at NuSea
NuSea

• NuSea meas 800 GeV p on Cu
• 9M J/? ? ??-
• 1st proton meas with enough stats to meas. xF
  dep
• no sep of direct decay J/?
• Systematics limited
• PT dep of production x-sect
• PT dep of acc vs. decay ang

Exp Int E GeV Pol
COM 0.35 0.65
E672/E706 ?- Be 515 ?0.010.08
p Be 530 0.010.15
p Be 800 ?0.110.15
E711 p Si 800 ?0.090.12
WA92 ?- Cu 350 ?0.010.19
NuSea/E866 p Cu 800 0.0690.0040.080
My Ave. 0.000.04

• NuSea consistent w/ prev meass of J/? pol at
  F.T.
• significantly more accurate
• All point to small J/? pol
• n.b. most include significant contrib from decay
  J/?s
• Disagreement w/ COM should be regarded w/ Caution

30
DIS Production of J/?
Years Lumi pb-1 N(J?) Main Systematics
H1 97-00 77 (ee,??) 458 30 Non-res bgrd, acc. eff.
ZEUS (prelim) 98-00 73 (??) 203 19 MC model of acc, diffr evts
ZEUS J/? ? ? ?-
Shape of ZEUS and H1 Data favor CSM but model
uncertainties are large
31
J/? Helicity at HERA
Years Lumi pb-1 N(J?) Main Systematics
H1 96-00 87 (??) Non-res bgrd, acc. eff.
ZEUS (prelim) 96-00 114 (??) 203 19 MC model of acc, diffr evts
not statistically significant yet !
32
Quarkonium Scorecard

• Production
• COM required by Tevatron
• but not by HERA
• Polarization
• no signif J/? pol obs
• few ? meass
• prompt vs non-prompt an issue in some meass
• Experiments largely syst dominated
• scale w/ stats ?
• Theory uncerts very larg
• quantitative statements difficult

33
New Particles with Heavy Flavor
CDF X(3872) hep-ex/0312021
CDF Charmed pentaquark search Preliminary (2004)
DØ X(3872) hep-ex/0405004
H1 Charmed pentaquark search hep-ex/0403017
ZEUS Charmed pentaquark search Preliminary (2004)
FOCUD Charmed pentaquark search Preliminary (2004)
SELEX Double charm baryon hep-ex/0406033
SELEX First observation of a narrow charm-strange meson hep-ex/0406045
see talks byRich Galik Takashi Nakano for more
on New Particles
34
The X(3872) in p-pbar
X(3872) ? J/? ? ?- 1st obs by Belle M
3872.00.50.6 MeV(previous hints at
E705,E706,E672 1994-95) Open question what is
it ? cc-bar? D0-D molecule? ccg hybrid?
something else?
Exp Lumi pb-1 range Mass MeV M res Signal Signif
CDF 220 y lt 1 3871.3 0.7 0.3 4.9 730 90 11.6 ?
DØ 230 y lt 2 3871.8 3.1 3.0 17 522 100 5.2 ?
prod. characteristics similar to ?(2S)but low
stats
M(??) gt 520 MeV
M(??) gt 500 MeV
35
Charmed Pentaquarks

• Strange Pentaquark
• observations by
• LEPS, DIANA, CLAS-1/2, SAPHIR, Asratyan, et al,
  HERMES, SVD, COSY-TOF, ZEUS, Spring-8
• not seen by
• BaBar, BES, Hera-B, PHENIX
• ltMgt 1530.5 2.0 MeV
• but not all meass consistent
• Charm Pentaquark
• critical issue p/K/? separation D ? D ?

Years Lumi pb-1 N(D) N(?c) Signif Mass MeV M res
H1 96-00 75 8.5K 51 11 5.4 ? 3099 3 5 12
ZEUS 95-00 127 43K
CDF 02-04 240 500K lt 29 (90CL)
FOCUS 96-97 36K
36
?c0 Search Results
H1 Signal not observed by other expswith
similar or greater sensitivity
37
New Particles at SELEX
confirm obs of ?cc(3520)
1st obs of DsJ(2632)
see talk by Peter Cooper
not obs in FOCUS or E791

• ?cc(3520)
• ?(pDK)/?(?K?) 0.0780.045 phase space ?
  0.22
• lifetimes appear lower than expect
• DsJ(2632)
• ?(Ds?)/?(D0K) 6 phase space ? 0.5
• very narrow ? lt 17 MeV

State Events Mass MeV Signif
?cc(3520) ? ?c K- ? 15.9 3519 1 6.3 ?
?cc(3520) ? p D K- 5.4 3518 3 4 ?
Ds(2573) ? D0 K 14 9 2569.9 4.3 5.4 ?
Ds(2632) ? Ds ? 45 9.3 2635.9 2.9 7.2 ?
Ds(2632) ? D0 K 14 4.5 2631.5 1.9 5.3 ?
38
Whats Next ?
Experiment Beam E TeV Runs Lumifb-1 ?tot(bb) Sample Stats
H1,ZEUS I e p 0.30/0.32 93-00 0.13 D 5x104
H1,ZEUS II e p 0.318 03-07 0.7 D 3.5x105
CDF,DØ I 1.8 92-96 0.125 100 ?b J/? 1.8x105
CDF,DØ II 1.96 02-08 49 10-15 J/? 3.16.9x107
BTeV 1.96 09 2 / y 100 ?b Reco B 107/y
Atlas,CMS pp 14 07-09 10 / y 500 ?b B?J/? 2x106/y
LHCb pp 14 07 2 / y 500 ?b B?J/?(??) 2x106/y

• Fixed Target continuing analysis of existing
  data
• possibility of new runs beyond 2009 ?
• New collider exps aim mainly at EW aspects of
  B-Physics
• Production studies will use exclusive final
  states
• Triggers are the critical issue ? Muon PT
• but keep an eye on the BTeV displaced vertex
  trigger !

39
A Taste of Whats to Come
Panikashvili, Smizanska 2003
CMS B?J/??
84K / 10 fb-1
Silvestris 2004
40
Where do We Stand ?

• b-Production
• big steps forward in understanding recently
• especially at the Tevatron, Fixed Target
• mild data-theory disagreement at HERA
• exp meass syst limited, theory errors quite
  large
• c-Production
• data-theory agreement remains fairly good
• but some discrepancies developing in new
  measurements
• again exp and theory uncertainties are large
• Heavy Quarkonia Production
• confusion regarding details of prod mechanism
  remains
• inconsistent(?) results for both production and
  polarization
• New Particles
• studies of their existence/properties starting

41
Where are We Going (soon) ?

• New Data is rolling in CDF,DØ,H1,ZEUS
• New Analyses are Proceeding Fixed Target
• b,c Production
• use new theoretical and analysis tools more
  widely
• extend kinematic reach of studies
• study correlations in production
• use production measurements to constrain PDFs
• Quarkonia
• better polarization measurements (prompt vs.
  non-prompt)
• more ? studies
• New Particles
• confirm/refute observations in question
• understand properties of those particles that
  survive

42
and Further Down the Road

• Upcoming collider exps Atlas,CMS,LHCb,BTeV
• superb detector capabilities
• huge heavy flavor samples
• But
• focus mainly on EW measurements in Q-sector
• rely critically on aggressive triggers
• Nevertheless
• there is an active heavy flavor effort (Hera-LHC
  Workshops)

Look for Exciting Heavy Flavor Reviews for many
Physics in Collisions to come