donatella lucchesi1 b physics review: part ii donatella lucchesi infn and university of padova rtn...

Donatella Lucchesi 1

B Physics Review: Part II

Donatella LucchesiINFN and University of Padova

RTN Workshop The 3rd generation as a probe for new physics

Bratislava, 4 – 6 July, 2003

Review of Tevatron measurements:

o B and b lifetimes and masses

o Bs Mixing New CDF results:

o Bs and b yields

o J/ cross sectiono D0 branching ratio and CP asymmetries


How do we collect b? Old style: o Di-muon trigger:

- 2 muons Pt > 1.5 GeV

(RunI Pt > 2 GeV)- charmonium physics- B lifetime, B mass, rare decays Bs

New era: Multi-bodies Hadronic trigger (SVT):

- 2 tracks Pt>2 GeV, |d|>120 m, Pt>5.5 GeV, Lxy>200 m- All you can imagine with BX where X>2

A combination of Old and New Lepton Pt>4 GeV (Run I Pt>8 GeV)+ track Pt>2 GeV |d|>120 m

- BlDX decays, flavor tagging optimization


D0: Results from J/ trigger


B Mesons Mass Measurements

The current results:

Decay modes:

Best in the world


b Hadrons Lifetime Measurements

Is it still interesting?

Several decays channels are available at Tevatron good test of the theory


b Hadrons Lifetime Measurement

Inclusive b lifetime: b J/ X

Experimental needs: calibrate resolution understand the alignments correction if not fully reconstructed decays

)(

TT

xyBPFP

ML

CDF result:

= 1.5270.0330.033 ps


Inclusive B J/X Lifetime at D0

)(

TT

xyBPFP

ML

MCMC

D0 Result:= 1.5610.0240.074 ps

D0 Run II Preliminary

D0 Run II Preliminary

First time at D0Use the same technique of CDF

PDG 2003= 1.5640.014 ps


b Hadrons Lifetime Measurement Exclusive lifetime with J/:

well measured

Simultaneous fitting of

MB: Extract signal fraction

ct: Extract the lifetime

B+ 1.57 0.07 0.02 (ps)

Bd 1.42 0.09 0.02 (ps)

Bs 1.26 0.2 0.02 (ps)

CDF Results:

)τ(B)τ(B

d

s

)τ(B)τ(B

d

= 0.89 0.15

= 1.11 0.09


News about b

Exclusive b lifetime (pre-blessed) Mass measurement (pre-blessed)

b J/


News about b cont’d

b cl [pK] l

Difficult to disentangle from decays through excited baryons

Semi-exclusive lifetime Branching ratio

And dE/dX


B Lifetime measurement: semi-leptonic decays

Useful to optimize B mixing and flavor tagging


Flavor tagging Lepton (muon and electron) tagging: under optimization in the huge sample of B lDX Same Side Tagging (SST): B0 (B0) accompanied by - (+)

bd

du

u

B0

+

A(t)= NRS(t) – NWS(t)

NRS(t) + NWS(t)

B0: A(t)= Dcos(m·t)

B±: A(t)= cost


Bs Lifetime measurement: semi-leptonic decays

Signal to noise ratio better than expected ! Observed yield: RunI5

Muons Electrons


Lifetimeand Perspectives

CDF lifetime expectation in 2 fb-1 are:

BsJ/ and BslDsX combined (/)few %

for both CDF and D0 CP asymmetry in BsJ/ expected small in S. M. If bigger new physics

If ms larger: difficult to measure also with high statistics sample sizeable easy to measurems = ·C where C can be calculated inside the S. M.

Semi-leptonic decays Fully reconstr. decays

(c)/c 2% 0.5%


Xs=msBs measurement: semi-leptonic decays

Decays included:Bs Ds

l, Ds*l(Ds

, K*0K, +)~40K events in 2 fb-1

Proper time resolution:

t = 60 fs t K/KK/K ~ 14%

Tagging:D2 = 11.3 % (all taggers)

Carlo Monte from )(

)(

)(

)()(

)(

)()(

st

st

st

ssxy

st

ssxy

BP

DlPK

KDlP

BMBL

BP

BMBLct

Sensitive up to xs 30

CDFCurrent limit Xs> 20.6


D0 :Bs mixing in fully hadronic decays

Decays included:Bs Ds

, Ds

(Ds, K*0K, K*K0)

BsJ/K*0

Proper time resolution:0.40 ps

Tagging:D2 = 3.1 % Jet

ChargeD2 = 4.7 % Lepton

S/B: 1:2

Fully reconstructed decays D0

CDF sensitive up to xs 60 old (Y.B.)

prediction


Offline Trigger confirmation 3D Vertex for D and B vertices 1.013<m(KK)<1.028 GeV Ds Mass constraint

R(Ds-)<1.5

xyB < 15 and xy

D < 10

PDs> 4 GeV and PtB>6 GeV

LxyD>400 m

LxyB>100 m

|dB|<100 m

Bs Yield Study: the cuts applied

Ds

Bs


Bs Yield Study: the signal

Can we measure the yield?• fs/fd: discrepancy LEP - CDF • Branching Fraction: unknown• Cross section: big uncertainty

First o

bservatio

n !


Bs Yield Study: the technique

Big effort in a full detector and trigger simulationoptimization “a la LEP” to measure the efficiencies

N(Bs)

N(Bd)=

fs

fd

s

d

Br(BsDs-+) Br(Ds

--) Br(k+k-)

Br(BdD-+) Br(D-k+--)

PDGMonte Carlo


• Same mode for:

• Similar cuts to signal

• also visible.

0S SB D

0b c

*D

Bs Yield Study: Normalization mode


Uncertainty in due to fit. s

d

B

B

N

N

s

d

B

B

N

N

0.008

0.008sB

dB

Particle

Uncertainty in s

d

B

B

Source /s dB B

XFT 1-miss

Min b quark tp

B lifetimes

D lifetimes

Total

0.001

0.08

0.02 0.04

0.00 0.04

0.08 0.06 BR Total Syst: 0.07

Due to MC

Bs Yield Study: Systematic


( )0.44 0.11( ) 0.11( ) 0.07( )

( )s s s

d d

f BR B Dstat BR syst

f BR B D

From PDG: 0.273 0.034 :s

d

f

f

( )1.61 0.40( ) 0.40( ) 0.26( ) 0.20

( )s s s

d d

BR B D fstat BR syst PDG

BR B D f

Bs Yield Study: Result


Bs Yield Measurement: where we are

Signal to noise optimization: S/B is optimized with >60%

Offline Trigger confirmation 3D Vertex for D and B vertices 1.010<m(KK)<1.028 GeV (only for Bs) D Mass constraint R(D-)<1.5 xy

B < 15 and xyD < 10

PD> 3 GeV (3.5 for Bs) and PtB>6 GeV (5.5 for Bs)

LxyD>-150 m

LxyB>250 m (400 for Bs)

|dB|<80 m Pt(B)>1.6 (1.9 for Bs)


Bs Yield Measurement: where we are

Signal to noise optimization


b c Relative Yield Measurement

Confirm trigger cuts Pt(proton)>2 GeV Pt( from b)>2 GeV Pt(c)>4.5 GeV Pt(b)>7.5 GeV c(b)> 225 m c(cfrom b)> -65 m d0(b)<85 m Pt(proton)>Pt( from c) 2.269<m(c)<2.302 GeV xy(b)<30 xy(c)<20

Same technique used for Bs


The Normalization Channel

B0D-+

same cuts optimizedfor b are applied


Many other B decays

BD+-

D±Ks ±


CP violation in Standard Model: at CDF R. Aleksan et al. Z Phys. C54 653 (1992) proposal: BsDs

K time dependent decay rate depends on:

sin() and cos()

a)Theoretically cleanb) Reasonable Branching ratioc) Background BsDsd) Need tagginge) Need time dependent analysis

~ 1000 events in RunIIa ~ 3500 events in RunIIb

S/B = 1/6

S/B = 1

Ds

Ds*K

Ds*

DsK


J/ cross sectionPt>1.5 Pt(J/)0

First time at Tevatron

(Pt>0, |y|<0.6)=240±1(stat) (syst) nb+35

-28


CP Asymmetries and Decays Ratios of D0h+h-

Two Tracks Trigger open CDF to a new field, charm physics

Pure D0 samples are required D* tag usedThe charge of the slow pion gives the D0 flavor



(D0KK)

(D0K)= 9.38 ± 0.18 (stat) ± 0.10 (syst) %

(D0)(D0K)

= 3.686 ± 0.076 (stat) ± 0.036 (syst) %

(D0f) - (D0f)

(D0f) + (D0f)ACP =

ACP() = 2.0 ± 1.7 (stat) ± 0.6 (syst) %

ACP(KK) = 3.0 ± 1.9 (stat) ± 0.6 (syst) %

Results competitivewith dedicated experiments and e+e-

machines i.e. CLEOFOCUS


Summary

CDF is starting doing competitive B physics measurements

D0 need more time since the new detector

In Italy many activities:

Bs branching ratio

analysis D0 branching ratio &

CP measurements No contribution on

J/ analysis Many opportunities

for students !

donatella lucchesi1 b physics review: part ii donatella lucchesi infn and university of padova rtn...

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