B physics at the TevatronB physics at the Tevatron B physics at the TevatronB physics at the Tevatron

UK HEP Forum“From the Tevatron to the LHC”The Cosener's House, Abingdon,UK

April 24-25, 2004

Rick Jesik Imperial College LondonRepresenting the DØ and CDF

collaborations

B physics at hadron collidersB physics at hadron collidersB physics at hadron collidersB physics at hadron colliders

Pros– Large production cross

section– All b species produced

B, B0, Bs, Bc, b, b

Cons– Inelastic cross section is a

factor of 103 larger with roughly the same pT spectrum

– Many decays of interest have BR’s of the order 10-6

– Large combinatorics and messy events

μb150)bbp(p

nbBBee 1)(

nb7)bbee(

at 2 TeV

at (4S)

at Z0

The CDF Run II detectorThe CDF Run II detectorThe CDF Run II detectorThe CDF Run II detector

The CDF detector has undergone extensive upgrades

– New silicon vertex detector inner layer at 1.35 cm

– New central tracker– Extended coverage– Time of flight detector– Second level impact

parameter trigger Allows all hadronic

b triggers

The DØ Run II detectorThe DØ Run II detectorThe DØ Run II detectorThe DØ Run II detector

The DØ detector has undergone very extensive upgrades

– Silicon vertex detector || < 3.0

– Central fiber tracker and pre-shower detectors

– 2 T solenoid magnet– Low pT central muon

trigger scintilators– New forward system– L2 silicon track trigger

commissioning now

DDØ extendedØ extended tracking coverage tracking coverageDDØ extendedØ extended tracking coverage tracking coverage

|| for kaons from D*D0pT spectrum of soft pion from D*D0

Tracks are reconstructed• over a wide range • starting from pT = 200 MeV

Data from semileptonic decays (B D X)

B triggers at the TevatronB triggers at the TevatronB triggers at the TevatronB triggers at the Tevatron

Dimuons – pT> 1.5 - 3.0 GeV – CDF central, DØ out to eta of 2

Single muons– DØ: very pure central track matched muons with

pT > 4 GeV, presence of additional tracks used at medium lums, impact parameters only used at high lums

– CDF: pT > 4 GeV/c, 120 m < d0(Trk) < 1mm, pT(Trk) > 2 GeV/c

Two displaced vertex tracks - hadronic sample– CDF: pT(Trk) >2 GeV/c, 120 m < d0(Trk) < 1mm,

pT > 5.5 GeV/c

Hadroproduction of heavy quarksHadroproduction of heavy quarksHadroproduction of heavy quarksHadroproduction of heavy quarks

NLO processes contribute with the same magnitude as LO ones

Lead to different kinematic correlations– R, , pT1 vs. pT2

R.D. Field - hep-ph/0201112

flavor creation flavor excitation gluon splitting

bb--quark cross sections at the Tevatronquark cross sections at the Tevatronbb--quark cross sections at the Tevatronquark cross sections at the Tevatron

Run 1 measured x-sections were a factor of two or three higher than the central values of the theory at the time.

Large uncertainties Large uncertainties Large uncertainties Large uncertainties

Experimental uncertainties– We don’t measure b-quarks, only B-hadrons

Fragmentation uncertainty – Peterson is not correct

– B decay products often not fully reconstructed Must extrapolate to B-hadron, then b-quark pT

Theoretical uncertainties– hard scatter really needs NNLO – scale factors (x2)– quark mass (10%), PDF’s (20%)– kT effects and fragmentation

Correlations between the above often not included in theory vs. experiment comparisons– Was this merely a 2 discrepancy? – or more?

An exotic explanationAn exotic explanationAn exotic explanationAn exotic explanation

SUSY gluino production and decay to b-quarks– Berger, Tait, Wagner

Also produce like sign BB hadrons and influence mixing measurements

Improvements in theoryImprovements in theoryImprovements in theoryImprovements in theory

New LO and NLO B-meson fragmentation functions determined from recent data – Binnewies, Kniehl, Kramer

Next to leading log resumation and re-tuned frag. functions: FONLL– Cacciari, Nason

Open charm cross sectionsOpen charm cross sections Open charm cross sectionsOpen charm cross sections

Charm production probes the same hard scatter processes as beauty, but has different fragmentation – good cross check of theory

Open charm cross sectionsOpen charm cross sections Open charm cross sectionsOpen charm cross sections

Same level of agreement or disagreement between data and theory (FONLL) as for beauty

D0D0 (pT≥5.5)

13.3±0.2±1.5 b

D+ (pT≥6) 4.3±0.1±0.7 b

D*+ (pT≥6)

5.2±0.1±0.8 b

Ds+ (pT≥8)

0.75±0.05±0.22 b

K

Inclusive Inclusive JJ// cross section cross section Inclusive Inclusive JJ// cross section cross section

CDF’s new muon trigger capabilities extend the J/ pT acceptance down to 0 – was 5 GeV in Run I.

Differential B Differential B J/J/cross sectioncross section Differential B Differential B J/J/cross sectioncross section

b-hadron x-section d/dpT(Hb)

Assume a b-hadron pT spectrum

Unfold pT(Hb) from pT(J/) using MC

New b-hadron pT spectrum

Iterate to obtain the correct pT spectrum

Differential dDifferential d/dp/dpTT(B) as function of p(B) as function of pTT(B)(B) Differential dDifferential d/dp/dpTT(B) as function of p(B) as function of pTT(B)(B) (ppB, |y|<0.6) * BR(B J/) * BR(J/+-) = 24.5 0.5(stat) 4.7(syst) nb

(ppb, |y|<0.6) =

18.0 0.4 3.8

b

Comparison to theoryComparison to theoryComparison to theoryComparison to theory

FONLL, a la Cacciari, Frixione, Mangano, Nason, Ridolfi

Impressive agreement with new data!

But… the measured inclusive x-section is at the same level as the Run I exclusive one – it should be 10-15% higher, due to the increase in beam energy.

Fully reconstructed B’sFully reconstructed B’s Fully reconstructed B’sFully reconstructed B’s

Better for cross section measurement – no missing decay product extrapolation uncertainties

Also very nice for correlations – hadron vs. other lepton or jet, or even other hadron!

More fully reconstructed B’sMore fully reconstructed B’s More fully reconstructed B’sMore fully reconstructed B’s

These states are not accessible at B-factories– CP violation in Bs, very small in SM – good place to look

for new physics– Bc coming soon

bb and B and BS S massesmassesbb and B and BS S massesmasses

M(Bs) = 5365.50 1.29 (stat) 0.94 (sys) MeV/c2

M(B) = 5620.4 1.6 (stat) 1.2 (sys) MeV/c2

World’s best measurements

Excited B hadronsExcited B hadronsExcited B hadronsExcited B hadrons

The X(3872) particleThe X(3872) particleThe X(3872) particleThe X(3872) particle

CDF has confirmed BELLE’s discovery of the X particle

• 730 730 90 candidates 90 candidates• ~~12 12 effect effect

MX = 3871.3 0.7 (stat) 0.4 (sys) MeV/c2

220 pb-1

DØ has also

confirmed the X(3872)

DØ results:

– 300 61 candidates– 4.4effect– M = 0.768 0.004 (stat)

0.004 (sys) GeV/ c2

– Direct (non-B) production

/)3872( JX

X(3872) production propertiesX(3872) production properties X(3872) production propertiesX(3872) production properties

D0 Run II Preliminary

dl < 0.02 cm 230 ± 59 evts

dl > 0.02 cm 77 ± 25 evts

X mass range decay length (cm)

X(3872) – X(3872) – (2S) comparison(2S) comparison X(3872) – X(3872) – (2S) comparison(2S) comparison

Is the X charmonium, or an exotic meson molecule? No significant differences between (2S) and X have been

observed yet

BB++ Lifetimes LifetimesBB++ Lifetimes Lifetimes

2 D mass, decay length fits

CDF: (B+) = 1.66 +/- 0.04 +/- 0.02 psDØ: (B+) = 1.65 +/- 0.08 +/- 0.12* ps

*systematics will be better soon

BBs s LifetimeLifetimeBBs s LifetimeLifetime

ps (sys) 0.14 (stat) 19.016.0190.1

Bsps (sys) 0.02 (stat) 148.0

129.0330.1 Bs

Bs/0=0.79 0.14 Bs/0=0.89 0.10

bJ/ Lifetime

B0 J/ K0s bJ/

(b) = 1.25 +/- 0.26 +/- 0.10 ps

B lifetimesB lifetimes B lifetimesB lifetimes

Same agreement for DØ Tevatron B+,B0 lifetimes are competitive Tevatron b ,Bs are the best

B hadron

CDF measurement (ps)PDG value

(ps)

B+ 1.66 +/- 0.04 +/- 0.021.674 +/-

0.018

B0 1.49 +/- 0.05 +/- 0.031.542 +/-

0.016

b 1.25 +/- 0.26 +/- 0.101.229 +/-

0.080

Bs 1.33 +/- 0.14 +/- 0.021.461 +/-

0.057

(B+)/(B0) from semileptonic decays (B+)/(B0) from semileptonic decays

Sample compositions:

“D0 sample”: + K+ - + (anything except slow )

B+ 82 % B0 16 % Bs 2 %

“D* sample”: + D0 - + anything

B+ 12 % B0 86 % Bs 2 %

Estimates based on measured branching fractions and isospin

(B(B++)/)/(B(B00): results): results (B(B++)/)/(B(B00): results): results

(B+)/(B0) = 1.093 0.021 (stat) 0.022 (syst)

Syst. dominated by:

- time dependence of slow reconstruction efficiency - relative reconstruction efficiencies CY

- Br(B+ + D*- + X) - K-factors - decay length resolution differences D0 D*

Bs MixingBs MixingBs MixingBs Mixing

Measures least known side of unitary triangle

Can not be done at B factories

Difficult measurement – requires:– High yield, good S/B– Oscillations are rapid,

so we need excellent lifetime resolution

– Flavor tagging

World average limit

Flavor taggingFlavor taggingFlavor taggingFlavor tagging

Opposite jet chargeSame side track charge

Q of the highest pT (or lowest pTrel) track in a cone (dR < 0.7) around the B

Muon charge

Q of the highest pT muon in the event separated in from the signal B by 2.2 rads.

iT

iiT

Σp

.qΣpQJet

Require |Q| > 0.2

b

b d

du

0

B

b

b d

du

0B

u u

Same side track flavor tagSame side track flavor tagSame side track flavor tagSame side track flavor tag

Same side tags on 1k BJ/K events (update with 4k events coming soon)

Flavor TaggingFlavor TaggingFlavor TaggingFlavor Tagging

For hadronic final states, DØ triggers on muon from other B – self tagging (=1) with even cleaner dilution due to higher pT threshold: ε D2 ~ 80%

Both experiments plan to use electron tags, and CDF will use kaons

Method DØ

Efficiency

ε (%)

DØ Dilution

D (%)

DØ Tag Power

ε D2 (%)

CDF Tag Power

ε D2 (%)

Jet Charge 46.7±2.7 26.7±6.8 3.3±1.7 In progress

Same side track

79.2±2.1 26.4±4.8 5.5±2.0 2.4±1.2

Muon Tag 5.0±0.7 57.0±19.3 1.6±1.1 0.7±0.1

BB00 mixing: results mixing: results BB00 mixing: results mixing: results

md = 0.506 0.055 (stat) 0.049 (syst) ps-1

250 pb-1

Bs mixing -Bs mixing - semileptonic decayssemileptonic decays Bs mixing -Bs mixing - semileptonic decayssemileptonic decays

Easy trigger on lepton in signal – good statistics– DØ: 38 events/pb-1

– CDF: 8 events/pb-1

Degraded proper time resolution due to missing neutrino– DØ: ~ 125 – 150 fs

– CDF: ~ slightly better

Tagging Power– DØ: ε D2 ~ 9 - 12%

– CDF: ε D2 ~ 3 - 8%

If ms ~ 15 ps-1 expect a measurement with 500 pb-1

Bs mixing -Bs mixing - hadronic decayshadronic decays Bs mixing -Bs mixing - hadronic decayshadronic decays

Difficult trigger, small BR’s – CDF: uses hadronic trigger

0.7 events/pb-1

– DØ: triggers on muon from other B in event: ~ 5 less events, but is starting

to see Bd all hadronic events

Excelent proper time resolution – CDF: = 67 fs

50 fs using inner silicon layer – D0: ~ 90 - 110 fs

will add inner silicon layer in 2005 Tagging Power

– DØ: ε D2 ~ 80 %, self tagging trigger

– CDF: ε D2 ~ 3 – 8 %Need a few fb-1 of data to reach ms > 18 ps-1

DsD*s

and

others

, , , and direct CPV, and direct CPV, , , and direct CPV, and direct CPV

Resolve the signal composition. Admixture of (at least):

B0d and Charge Conjugate

B0d K+ - and C. C.

B0s KK- and C. C.

B0s K- + and C. C.

pT > 2 GeV/c: TOF doesn’t help

Combine kinematics with dE/dx to achieve statistical separation

Expect ~ 6500 evts / fb-1

MC

Lumi ~ 180 pb-1

ConclusionsConclusionsConclusionsConclusions

Since the 2003 fall shutdown, the Tevatron has shown substantial improvements

Spring is here, and the Tevatron is blooming with beautiful B results– Some have already been published, many are close

B cross sections, masses, and lifetimes X production studies

Both Experiments are poised to attack Bs mixing in semi-leptonic and hadronic decays.– Bd mixing measured– Expect first Bs results this Fall/Winter

Longer term, many CKM measurements (and other interesting analyses) are in the works.