donatella lucchesi1 b physics review: part ii donatella lucchesi infn and university of padova rtn...
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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
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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
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D0: Results from J/ trigger
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D0: Results from J/ trigger
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B Mesons Mass Measurements
The current results:
Decay modes:
Best in the world
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b Hadrons Lifetime Measurements
Is it still interesting?
Several decays channels are available at Tevatron good test of the theory
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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
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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
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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
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News about b
Exclusive b lifetime (pre-blessed) Mass measurement (pre-blessed)
b J/
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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
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B Lifetime measurement: semi-leptonic decays
Useful to optimize B mixing and flavor tagging
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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
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Bs Lifetime measurement: semi-leptonic decays
Signal to noise ratio better than expected ! Observed yield: RunI5
Muons Electrons
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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%
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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
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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
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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
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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 !
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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
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• Same mode for:
• Similar cuts to signal
• also visible.
0S SB D
0b c
*D
Bs Yield Study: Normalization mode
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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
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( )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
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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)
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Bs Yield Measurement: where we are
Signal to noise optimization
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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
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b c Relative Yield Measurement
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The Normalization Channel
B0D-+
same cuts optimizedfor b are applied
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b c Relative Yield Measurement
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b c Relative Yield Measurement
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Many other B decays
BD+-
D±Ks ±
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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
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J/ cross sectionPt>1.5 Pt(J/)0
First time at Tevatron
(Pt>0, |y|<0.6)=240±1(stat) (syst) nb+35
-28
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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
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CP Asymmetries and Decays Ratios of D0h+h-
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CP Asymmetries and Decays Ratios of D0h+h-
(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
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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 !