H.Evans U Penn HEP Seminar: 7-Nov-00 1 B-Physics at DØ (coming attractions) Hal EvansColumbia U. Outline: I.Why B-Physics? II.Why DØ? III.Wild Predictions

H.Evans U Penn HEP Seminar: 7-Nov-00 1

B-Physics at DØ (coming attractions)

B-Physics at DØ (coming attractions)

Hal EvansColumbia U.

Outline:

I. Why B-Physics?

II. Why DØ?

III. Wild Predictions & Comparisons!


Philosophy 101(B)Philosophy 101(B)

Why should we study the b-Quark?

1. Probes an area of the SM that is poorly understood CKM Matrix & CP-Violation

2. Sensitive to Physics beyond the Standard Model b-quark is the most massive

fundamental particle that is easily accessible

3. Important input to QCD & models used in other measurements B-Hadron properties lend

themselves to modelling crucial in studying Higgs, t-

quarkLEP EW-WG: Summer 00


Stalking the Wild b-QuarkStalking the Wild b-Quark Mass (3rd Family) mb ~ 4.5 GeV

couples to t-quark couples to New Physics perturbative QCD regime

Lifetime ~ 1.6 ps a useful ID tool

Spectroscopy light-q mesons: heavy-q mesons: baryons:

Decays ~25 modes meas (B0) 165 modes listed by PDG light quark spectator

Mixing

md~0.47ps-1 ; ms>15ps-1

CP Violation large effects (>10%) in some

modes

0du BB ,

,, 0sc BB

),,(, 0b

00 BB

)B((B)

b s

H±

t

0dB *D

b c

d

W

V*td

b

b

d

dt

tB0 B0W W


Their Natural HabitatsTheir Natural Habitats

Acceptance at DØ

Tevatron Run II

LEP CLEO B-Fact LHC

Type p e+e- e+e- e+e- pp

Ecm [GeV] 1960 91 10.5 10.5 14000

[b] ~150 0.007 0.001 0.001 ~500

b Rate [Hz] 30,000 0.35 0.3 2 500,000

S/B [%] 0.1 0.15 ~0.3 ~0.3 0.6

<Decay Length> [mm] 2 3 0.025 0.26 1.7 (Lxy)

)bb(

PT(B) > 4 GeV

} Accept ~ 31% |y(B)| < 3.0


Glorious Tevatron HistoryGlorious Tevatron History

Run I b-Physics Publications CDF – 50 DØ – 7

b Production X-Section + correlations

J/ Production + polarization

Production —

b Fragmentation —

Branching Ratios J/ states —

Masses Bs,Bc,b —

Lifetimes B,B0,Bs,Bc,b —

Rare Decays , K*, e s

B Mixing Bd, Bs

states: manytags: l,Qjet,SST

—

sin 2 J/ Ks0 —


ch- ch- ch- ch- Changes!ch- ch- ch- ch- Changes!

Major upgrade to the Tevatron nearing completion main injector antiproton recycler

First collisions in 36x36 mode last week !

Ib IIa IIa (?) IIb

Tot. Anti-p (x1012) 0.3 1.1 4.2 11

Bunches 6x6 36x36 140x103 140x103

Spacing [ns] 3500 396 132 132

E-CM [GeV] 1800 1960 1960 1960

Typ. Lumi. [cm-2s-1] (x1032)

0.16 0.86 2.1 5.2

Lumi/week pb-1 3.2 17.3 42 105

Tot Lumi fb-1 0.125 2-4 15-20

Int’s/X’ing 2.5 2.3 1.9 4.8


DØ Run II UpgradeDØ Run II UpgradeCentral Scintillator

Forward Mini-drift chamb’s

Forward Scint

Shielding

Tracking: Solenoid,Silicon,Fiber Tracker,Preshowers

New Electronics,Trigger,DAQ

Calorimeter

Central PDTs


Detector PerformanceDetector PerformanceDØ – Run I DØ – Run II CDF – Run II

Field T 0 2.0 1.4

Tracking

accept <3.0 <3.0(Si) ; <1.7 (CFT) <2.0(Si) ; <1.0(COT)

Radii cm 3.7-75 2.8-10.0(Si) ; <52(CFT) 1.6-10.7(Si) ; <132(COT)

PT/PT % — 20.2pt 0.70.1pt

Imp par m — 1350/pt 622/pt

Prim Vtx m 15-30(r) 10-35(r)

Sec Vtx m — 40(r) ; 80(rz) 14(r) ; 50(rz)

Mass res (J/) MeV — 27 16

PID PreShower dE/dx,TOF

accept <4.0 <3.6Calo

0.10.1 0.10.26

EM res % 14/E 16/E

Jet res % 80/E 80/E

accept <3.6 <2.0 <1.5Muon

cover 90% increase scint 80% (cen)

Shield I 12-18 beam shielding 5.5-20

P/P % 18 0.3p —


Triggering on B’sTriggering on B’s

Handles: Tracks:

rates too high for DØ Leptons: BR(BlX)~11%

only DØ tool at L1 Displaced V’s: <L>~2.3 mm

Si info used at L2 Mass, Isolation, etc…

L2, L3

-

+

-

+

-b

b

/J0sK

Process X-Sect. Rate(L=21032)

Inelastic pp 50 mb 10 MHz

bb (|y|<1) 50 b 10 kHz

pp WX 22 nb 4.4 Hz

ZX bbX 1 nb 0.2 Hz

pp tX 11 pb 8 / hour

pp W/Z H 0.5 pb 8 / day

multi-level trigger required

multi-level trigger required

+


Triggering at DØTriggering at DØ

L14.2 s

(128 terms)

L2100 s

(128 terms)

L350 ms

(48 nodes)

Framework7 MHz

10 kHz 1 kHz 50 Hz

Data

• Single Sub-Det’s

• Towers, Tracks, ET-miss

• Some correl’s

• Not deadtimeless

• Correlations

• Calibrated Data

• Physics Objects e,,j,,ET-miss

• Simple Reco

• Physics Algo’s


L1 & L2 SystemsL1 & L2 Systems

L2FW:Combined objects (e, , j)

L1FW: towers, tracks

L2STT

Global L2

L2CFT

L2PS

L2Cal

L1PS

L1CFT

L2 MU

L1 MU

L1FPD

Detector L1 Trigger L2 Trigger

7 MHz 10 kHz 1 kHz

CAL

FPS CPS

CFT

SMT

MU

FPD

L1CAL


The DØ Silicon Track TriggerThe DØ Silicon Track TriggerTrigger Benefits Improved Momentum Res:

factor 23 Sharper Thresholds

Impact Param at Trigger Resolutions:

~ 30m at PT=2GeV 15m at PT=15GeV

Physics Benefits New Phenomena

incr Higgs sens 20%

ZHbb double sens

hAbbbb Top

Trigger on Zbb (increase yield x6) Cut Mt Syst in half

B-Physics Increase BKS yield by 50%

General Reduce e Rate by a factor of 2

50 s Time Budget

Raw Datafrom Si

Detector

Cluster Finder

Tracks fromFiber Tracker

(L1 Trig)

Associate Clustersto Tracks

Re-Fit Trackw/ Si Clusters

Global L2 Trigger

Define SearchRegion

Online: summer 2002


DØ Now !DØ Now !

Subsystem Status Future

Silicon all comp’s in handS=done; N>2/3

install S:this week; N:12/00

Fiber tracker Installed finish cabling

Tracker Electr production complete 2/01

Solenoid working

Cen & Fwd Preshowers installed

Intercryostat det. installed

Calorim Electronics production complete 12/00

Luminosity Mon. measuring lumi

Muon Central installed commisioning

Muon Forward installing complete 11/00

Trigger & DAQ prod & use complete 3/01

Online in use help commisioning

Installation on schedule complete 2/01

Computing purchased commissioning


DØ Ambitions in Run IIDØ Ambitions in Run II

QCD Tests X-Sections & Correlations

Excl. Decays, l+Jet Incl., ll Onium Physics

J/, X-Sect’s and Pol. Fragmentation

B-Hadrons (B,B0,Bs,Bc,b) Spectroscopy Lifetimes Pol. & Helicity Analyses

Rare Decays B l+l-, l+l- K*

Bs K*

B Mixing Bs lX, Ds, J/K*

Bd (t-dep): Tagging Studies

CP Violation & CKM J/Ks

0

sin 2 , KK

(limits) + Bs J/

non-SM


B ProductionB Production Theory says… Yes!

mb>>QCD: NLO should work but scale uncertainties large

Experiment says… Kinda! normalization x2.5-4 high shape ~OK (but – high vs low PT)

correlations as expected from Higher Order

nagging uncertainty PDFs (note personal bias!)

New for Run II (DØ) exclusive final states vertex tagging electrons more correlation studies


CP Violation and the CKM MatrixCP Violation and the CKM Matrix

CP Violating Asymmetry

SM expl for CP Asym in K & B: Complex Phase in CKM

Wolfenstein param: O(4)

Unitarity of VCKM 12 eqn’s the Unitarity Triangle is one

b

s

d

VVV

VVV

VVV

'b

's

'd

tbtstd

cbcscd

ubusud

112

11

2

11

23

22

32

A)i(A

A

)i(A

)fB()fB(

)fB()fB(ACP

(0,0) (0,1)

(,)

( ~ sinc)

0 *tdtb

*cdcb

*udub VVVVVV

)KJ/(B 0ψ

VV

VVarg

*tbtd

*cbcd

)(B

*ubud

*tbtd

VV

VVarg

)hh(B

*cbcd

*ubud

VV

VVarg

mixing) (Bts

td

V

V

X)(B

cb

ub

V

V


but does it All Fit?but does it All Fit? Many measurements

constrain CKM param’s but no real test of whether

CP-violation is described by SM or not

Two Possibilities1. all angle/sides consistent w/

a triangle Hooray for the SM !

2. no triangle fits all meas’s New Physics !

Why expect New Phys here? many beyond SM models

have additional CP-violation matter – antimatter asym not

consistent w/ SM CP


What can We Do About It?What can We Do About It? Easiest angle to measure is

use time dependent CP asymmetry in BdJ/Ko

Theoretical uncertainties small ! Need to tag Flavor of B at production

remember: it can mix before decaying

)K/JB(N)K/JB(N

)K/JB(N)K/JB(N)t(A

sdsd

sdsdCP 0000

0000

)tmsin()sin( d 2

*

cdcs

cd*cs

*cbcs

cb*cs

*tdtb

td*tb

VV

VV

VV

VV

VV

VVIm)sin( 2

Bd Mixing (f)/A(f)A K Mixing


B J/ Ks: ExperimentallyB J/ Ks: Experimentally

Experimental Technique measure Lxy t tag initial flavor worry about asymmetric

systematics

Experimental Advantages Leptons for triggering simple, excl final state J/ & Ks mass constr’s

(some) Tagging Possibilities Opposite Side Lepton Opposite Side Jet Charge Same Side Fragmentation

+ -

+

-

+

-b

b

/J0sK


Opposite side tags: identify the flavor of the other B in

the event soft lepton tags b l - + X jet charge tags Qjet < 0 for b

Same side tags: correlation of flavor and charge of

closest particle produced in fragmentation or decay

Flavor TaggingFlavor Tagging

Efficiency () and

dilution factor (D)

D = 2 P - 1 P is the correct tag probability

D2 is the tag’s effectiveness

Efficiency () and

dilution factor (D)

D = 2 P - 1 P is the correct tag probability

D2 is the tag’s effectiveness

B0

u

d

b

-

B0

b b

u

-

B**- d


B J/ KS ReconstructionB J/ KS Reconstruction

J/ + -

two muon tracks pT > 1.5 GeV/c | | < 2


B J/ KS ReconstructionB J/ KS Reconstruction

•KS + -

• pT () > 0.45 GeV/c

• pT (KS) > 0.75 GeV/c

• | | < 1.8

• Lxy/ > 5

•Combined +- +-

invariant mass • (before fit)


B J/ Ks decay length reconstructionB J/ Ks decay length reconstruction

• Two secondary two-track vertices

• Average B decay length: 2.3 mm

• Measured decay length resolution: 100 m


BJ/Ks ReconstructionBJ/Ks Reconstruction

J/+-

2 Muons: ||<2.0, PT>1.5GeV

Ks+-

Long lifetime rejects bgrd Lxy/ > 5

4-Track Constrained Fit mass: J/, Ks

vertex: KsB, B primary

Decay Length Resolution 100 m

unconstr:

= 41 MeV

constr:

= 10 MeV


EffectivenessEffectiveness

Tag

D 2 (%) measured

CDF Run I

D 2 (%) expected

CDF Run II

Relevant

DØ difference

DØ capabilities

Same side 1.8 2.0 same 2.0

Soft lepton 1.7 e ID

coverage 3.1

Jet charge 0. 8 3.0 forward tracking 4.7

Opp. side K 2.4 no K ID none

Combined 9.1 9.8

Measure of tagging weight

• Quality = D2

• = efficiency of tag

• D = (2P – 1) P = correct tag prob


sin(2) Expectations (2 fb-1)sin(2) Expectations (2 fb-1)

DØ Assumptions: S/B ~ 0.75 D2 = 9.8% Time res: t ~ 100 fs 2.0 fb-1 of data

S

B

NDx

xe)(sin

d

dx td

11

2

412

2

2222

J/+- J/e+e-

Trig Eff (%) 27 20

N(reco evts) 40000 30000

sin(2)0.04 0.05

0.03


sin2 Past, Present & Futuresin2 Past, Present & Future

Exp. Meas N(events) D2 (%) Data

Opal LEP1

Aleph 23 LEP1

BaBar(*) 0.12±0.37±0.09 120 27.9 9.0 fb-1

Belle(*) 98 21.2 6.2 fb-1

CDF Run I 395 ~2.0 0.11 fb-1

Run II ±0.043 28K() 9.1 2.0 fb-1

DØ Run II ±0.03 40K()+30K(e) 9.8 2.0 fb-1

BTeV ±0.017 109K 10 1 year

HeraB ±0.16 720 1 year

Atlas ±0.017 160K()+5K(e) 3() – 30(e) 1 year

CMS ±0.015 490K()+40K(e) ~3 1 year

0.53.2 1.82.0-

0.160.84 0.821.04-

0.410.44-0.79

0.070.09-

0.430.44-0.45

(*) Preliminary


Rare Decays and FCNCsRare Decays and FCNCsTheoretically FCNC B0 decays forbidden at

tree level in SM

Beyond SM effects could be large !

Experimentally Triggering

Leptonic Modes: easy

Event Reconstruction +-

easy – but low BR B mass secondary vertex isolation

+-K*

promising all of above + K* ID cut out resonances

+-Xs

difficult small M() window large backgrounds

b s

W

tb s

H±

t

Mode BR(Bd) BR(Bs)

+- 1x10-10 4x10-9

+-K* () 1.5x10-6 1x10-6

+-Xs 6x10-6

K* 4.4x10-5


Beyond the SM w/ Rare DecaysBeyond the SM w/ Rare Decays

+-

in 2 Higgs-Doublet Model

+-K*

)pp(N)pp(N

)pp(N)pp(NA

2

2

W

bSMHDM M

tanm

Ali,Ball,Handoko,Hiller – hep-ph/9910221

SM MIA-SUSY(C10)>0

SUGRA

MIA-SUSY


Bd+-K* AsymmetryBd+-K* Asymmetry

Expect ~700 events in 2 fb-1

Asymmetry results (plot d) A = 0.11 ± 0.11 m < 2 GeV A = -0.33 ± 0.06 m > 2 GeV

To do Bde+e-

B+l+l-K+

Generated distrib’s

Reconstructed: no bgrd (a,b)

Reconstructed: S:B=1:1 (c,d)

)pp(N)pp(N

)pp(N)pp(NA


Big List o’ PredictionsBig List o’ Predictions

State N(evts) Meas. Sens Current

BdJ/K0 70K sin2~0.03 sin2=0.48±0.23

Bd+- 300-600 ? B=(9.3±2.9)x10-6

BdK+- 1300-1600 ?B=(12.5±3.3)x10-6

Bs+K- 150-300 ?

BdK+K- 650-1300 ? B<4.3 x10-6

Bs Mixing 700-2100 xs=20-30 xs>22 ps-1

b 30K-80K (b)~0.16 ps (b)=1.23±0.08 ps

BcJ/l 600 ? m(Bc)=6.4±0.4 GeV

(Bc)=0.46±0.18 ps

B+-K* 700 A~0.06 B<4.0x10-6

B+-Xs 1000 (S/B=0.03-0.1) ? B<5.8x10-5

B+- 0 (if SM) ? B<6.8x10-7all predictions for 2 fb-1 of data


ConclusionsConclusions

How can you have a conclusion when you haven’t started yet ?

Documents

H.Evans U Penn HEP Seminar: 7-Nov-00 1 B-Physics at DØ (coming attractions) Hal EvansColumbia U. Outline: I.Why B-Physics? II.Why DØ? III.Wild Predictions