1 b physics at d0: an update vivek jain cornell university oct 1, 2004
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B Physics at D0: An update
Vivek JainCornell University
Oct 1, 2004
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Outline
Introduction D0 detector Recent Results
New states Rare decays Lifetimes Mixing
Conclusions
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Why B physics? Understanding structure of flavour dynamics is
crucial 3 families, handedness, mixing angles, masses, … any unified theory will have to account for it –
Weak decays, especially Mixing, CP violating and rare decays provide an insight into short-distance physics
Short distance phenomena are sensitive to beyond-SM effects
Test bed for QCD, e.g., form factors, calculations of B hadron lifetimes, spectroscopy
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B physics at the Tevatron
At Ecm = 2 TeV
At Z pole
At Υ(4S)
All species produced,
bbbpp 150)(
nbbbee 7)(
nbbbee 1)(
...,, bsc BB
Environment not as clean as at electron machinesLow trigger efficiencies
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B Physics Program at D0
Unique opportunity to do B physics during the current run Complementary to program at B-factories (KEK, SLAC, CLEO..)
mixing, Rare decays: Large tanβ SUSY models enhance rate
Beauty Baryons, lifetime, … expt: 0.80±0.06 (SL modes), theory ~ 0.95
, , B lifetimes, B semi-leptonic, CP violation studies Quarkonia - production, polarization …
SB SB
CB
,ψ/J
b
SS /
b production cross-section: In Run I, measd. Rates x(2-3) higher
)(/)( 0db B
**B
b
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DZero Detector
SMT H-disks SMT F-disks SMT barrels
Muon system with coverage |η|<2 and good shielding
TrackersSilicon Tracker: |η|<3Fiber Tracker: |η|<2
Magnetic field 2T
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8 Layers: Axial, Stereo (± 3°)Radius: 20-50 cm
Readout by VLPC:High QE, very low dark noiseExcellent PE resolutionEach pixel has 1mm radius – well matched to fiberOperated at 8-9 (± 0.05)°K
Good S/N. Signal ~ 5-9 pe
Fast enough to be in L1 trigger
CFT
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VLPC performance
Signal ON: LED wasset to ~ 2 pe
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πKD μX,DB 00
2.2)(GeV,2)( TpAll tracks
Analysis cuts – pT>0.7 GeVσ(DCA)≈53μm @ Pt=1GeVand better @ higher Pt
data
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pT spectrum of soft pion candidate in D*D0
~100 events/pb-1
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Excellent Lepton Acceptance
Muon ID:
Tp
MC: πμX, DDB ss
of reconstructed muon
Overall efficiency (from data)plateaus at about 85-90%
- at pT 4.5 GeV
pT 3.5 GeV
- at pT 2.5 GeV
6.0
2.16.0
2.1
Muon system in Level 1
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Calorimeter goes out to
Low pT electron ID is in progress
At present, we can detect electrons with pT>3 GeV and Average efficiency is about 75% Working to extend to higher values of and lower pT threshold – use for tagging initial state flavour
1.1
Electron ID:
4
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All trigger components have simulation software
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Triggers for B physics
Robust and quiet di-muon and single-muon triggers Large coverage |<2, p>1.5-5 GeV – depends on Luminosity
and trigger Variety of triggers based on - Muon purity @ L1: 90% - all
physics! L1 Muon & L1 CTT (Fiber Tracker) L2 & L3 filters
Typical total rates at medium luminosity (40 1030 s-1cm-2) Di-muons : 50 Hz / 15 Hz / 4 Hz @ L1/L2/L3 Single muons : 120 Hz / 100 Hz / 50 Hz @ L1/L2/L3 (prescaled)
Current total trigger bandwidth 1600 Hz / 800 Hz / 60 Hz @ L1/L2/L3
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Recent Results
Many new analyses used ~ 250-350 pb-1
Single muon triggers have variable prescales, non-trivial to determine luminosity for analyses using these triggers
Have more data on tape, but not yet analyzed
Details at: www-d0.fnal.gov/Run2Physics/ckm/
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Basic particles
Plot is forillustrativepurpose
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Large exclusive samples
~ 350 pb-1
Impact parameter cuts
7217±127
2826±93
624±41
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~ 250 pb-1
Will reprocess w/ trackingoptimized for long-lived part. (yield will ~50%)
No IP cuts:Use for lifetime
337±25
Bs
Λb
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Observation of X(3872)
In 2003, Belle saw a newparticle at 3872 MeV/c2, observed in B+ decays:B+ K+ X(3872), X(3872) J/ + -
Belle’s discovery has been confirmed by CDF and DØ.
DØ (accepted by PRL) 522 ± 100 events
M = 0.7749 0.0031 (stat) 0.003 (syst) GeV/c2
5.2 effect
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22(Estia Eichten) J_PC
Charmonium
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What kind of particle is the X ?
- charmonium ? 1 ³D3, 2 ³P2 …
- an exotic meson molecule ?
- something else ?
Compare X candidatesto (2S), e.g.
- split into two || regions
- decay length, isolation, helicity
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No significant differences between(2S) and X have been observedyet.
This comparison will be moreuseful once we have models ofthe production and decay of, e.g.,meson molecules that predictthe observables used in thecomparison.
Observation of the charged analog X+ J/ + 0 would rule out charmoniumObservation of radiative decays X c would favour charmonium Belle’s results rule out 1 ³D3, 2 ¹P1, ³D2, ¹D2, 0-+, 1++ Use Dzero’s calorimeter to identify low energy 0 and : work in progress.
pT>15
|y|<1
Hel(ππ)<0.4 dl<0.01 cm
Iso=1
Hel(μμ)<0.4
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Spectroscopy: L=1 B (and D) mesons
For Hadrons with one heavy quark, QCD has additional symmetries as
(Heavy Quark Symmetry)
Spin of the heavy quark decouples and meson properties are given by the light degrees of freedom
Each energy level in the spectrum of such mesons has a pair of degenerate states:
QCDQm
Qqq sjJj
,Lsj qq
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For non-strangeL=1 Charm mesonsjq = 1/2, 3/2 havebeen seen
Belle hep-ex/0307021
MeV25
MeV300
Lessons from charm (I)
The wide states were observedvia Dalitz plot analysis in
(*)DB
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D** at D0
Preliminary result on product branching ratioBr(B {D1
0,D2*0} X) Br({D10,D2*0} D*+ -)
= 0.280 0.021 (stat) 0.088 (syst) % measured by normalizing to known Br (B D*+ X)
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Lessons from charm (II) – Ds**
jq = 1/2 below DK threshold, decay to
Mass/widths unexpected!
Maybe B** or Bs** have similar behaviour
For L=1 Ds mesons,
preferred decay mode:DK
jq = 3/2 -> DK, D*K
(*)0(*) / ss DD
Eichten
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Previous results on B**
Previous experiments did not resolve the four states:
<PDG mass> = 5698±8 MeV
Theoretical estimates for M(B1)~ 5700 - 5755 and for M( ) ~ 5715 to 5767. Width ~ 20 MeV
Experiment B reconstruction BJ mass (MeV) BJ width
ALEPH exclusive 5695±18 53±16
CDF (μD)+π 5710±20 -----
DELPHI inclusive B + π 5732±21 145±28
OPAL inclusive B + π 5681±11 116±24
Probably not the naturalwidth of these states
*2B
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Signal reconstruction (I)
Search for narrow B** - Use B hadrons in the foll. modes and add coming from the Primary Vertex
Since ΔM between B**+ and B**0 is expected to be small compared to resolution, we combine all channels (e.g., ΔM for B+/B0 = 0.33±0.28 MeV)
KJB /
KKKJBd0*0*0 ,/
000 ,/ KKJBd
7217±127 events
2826± 93 events
624± 41 events
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Signal Reconstruction (II)
Dominant decays modes of ( forbidden by J,P
conserv.) (ratio of the two modes expected to be 1:1)
To improve resolution, we measure mass difference between and B, ΔM
BBBB **1 ,
BBBB ***2 ,
BB *2
B
*21, BB
*21, BB
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Signal reconstruction (III)
Now, ΔM(B* - B) = 45.78±0.35 MeV – small Thus, if we ignore , ΔM shifts down ~ 46 MeV,
MeVBMBMBBM 46*)()()( *
2*2
We get three peaks: = M( ) – M(B*) – 46 MeV = M( ) – M(B*) – 46 MeV = M( ) – M(B) - in correct place
1B*2B*2B
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BB *2
BBBB ***2 ,
BBBB **1 ,
From fit:
N = All B**
536±114events
First observation of the separated states
~7σ signif.
Interpreting the peaks as:(98)
273±59 events
131±30 events
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B0**
B±**
Consistency checks:
required to have large Impact parameter signific.relative to Primary vertex – No Signal (as expected)
32±36 events
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Results of fit - Preliminary
21 /)(7)(45724)( cMeVsyststatBM
21
*2 /)(9.3)(7.76.23)()( cMeVsyststatBMBM
221 /)(9)(1223 cMeVsyststat
)(21.0)(11.051.01 syststatf
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sB
Standard Model predictions
Exptl. Results 90% (95%) CL
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Beyond Standard Model
First proposed by Babu/Kolda as a probe of SUSY (hep-ph 9909476)
Branching fraction depends on tan(β) and charged Higgs mass
Branching fraction increases asin 2HDM (MSSM)
)(tantan 64
Other models also have enhanced rates, e.g.,
Dedes, Nierste hep-ph 0108037mSUGRA
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Experimental challenge: (L 200 pb-1)
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Optimization Procedure – “blind” analysis
~ 80 pb-1 of data was used to optimize cuts After pre-selection, three additional variables were
used to discriminate bkgd. from signal - Isolation : Since most of b-quark’s mom. is carried by
the B-hadron, track population around it is low
Decay Length significance: Lxy/δLxy – remove combinatoric background, e.g., fake muons
Pointing angle: Angle, α, between B_s decay vector and B_s momentum vector
))1(|)(/(||)(|
Bi
i RpppI
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Pointing angle < 0.20 (rad)
Result of optimization
δLxy/ δL > 18.5
Isolation > 0.56
Background prediction from sidebands in (MB ± 2σ): 3.7 ± 1.1 events
Punzi (physics/0308063)
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Opened the box (July 8’ 04)
Nothing remarkable about the four events – look like background!
(L = 240 pb-
1)
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Calculate upper limit (I)
To calculate limit on branching fraction, normalize to
KJB /
Bs
Bd
dBubBsb
Bs
BK
B
uls
Rff
JB
N
NB
.)/(
)/().(..)
,
21 BBBr(
0.270±0.034 (PDG)
Since our signal region overlaps Bd, can have contaminationR: theoretical expectation for ratio of Br. frac. of Bd /Bs - set R=0If limit will be better
Feldman-Cousins
PDG
MC: 0.229±0.016 MC
0R
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Upper Limit - Preliminary
The 95% (90%) C.L. upper limit:
)108.3(106.4)( 77 sBBr
If we use Bayesian approach, we get 4.7 (3.8)
Currently, the most stringent limit on this decay channel
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Implications of this resultExcluded by D0 Run II 240 pb-1
Dermisek et alHep-ph 0304101
Dark Matter andMinimal SO10 with soft SUSYbreaking
sB
Allowed by Dark Matterconstraints
Contours of constant)( sBBr
4.6E-7 (95%CL)
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Observation of Bc
Last of ground state mesons to be definitively observed!
Theory: Lifetime 0.3-0.5 ps
Theory: Mass 6.4 GeV ±0.3
Only previous evidence CDF RunI result
20.4 signal+6.2- 5.5
Mass: 6.4±0.39±0.13 GeV
0.46 0.03 ps+0.18
- 0.16
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Take advantage of easy-to-trigger-on final state – events come via the dimuon triggers
Bc+
+
+-
PV
Select 231 J/X candidates
Background estimated with J/+track data control sample, separated into prompt and non-prompt components
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Do combined likelihood fit to invariant mass and pseudo-proper time distribution:
#signal: 95±12±11
Mass:
5.95 ±0.34 GeV+0.14
-0.13
Lifetime:
0.448 ±0.121 ps+0.123
-0.096
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Background-only fit:
2log(likelihood) is 60 for 5 degrees of freedom
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Other properties:
b
b
cc
Bc
Forms weakly decaying charmed hadron
Probability 4th within ±90 degrees of Bc candidate = 5±2%
Probability 4th within ±90 degrees of background = 1%
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Lifetimes of B hadrons
Use modes with J/ψ final states, semi-leptonic decays
Predictions available from theory via OPE calculations
These calculations are rooted in QCDExpansion is in inverse powers of heavy quark massPredictions are semi-quantitative for CharmFor B-hadrons, predictions are on much firmer footing
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“D0 sample”: + K+ - + anything
B+ 82 % B0 16 % Bs 2 %
“D* sample”: + D0 - + anything
B+ 12 % B0 86 % Bs 2 %
Estimates based on measured branching fractions and isospin relations.
(B+)/(B0) from semileptonic decays
Novel idea: Signal with Imp. Param cuts
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Group events into 8 bins of Visible Proper Decay Length (VPDL):Measure ri = N(+ D*-)/N(+ D0) in each bin i.
Minimize:
Additional inputs to the fit:
- sample compositions (previous slide)
- K-factors (from MC) – missing particles
K = pT(D0) / pT(B) [separately for different decay modes]
- Relative reconstruction ε for different B decay modes (from MC)
- Slow pion reconstruction ε [flat for pT(D0) > 5 GeV (one of our cuts)]
- Decay length resolution (from MC)
- (B+) = 1.674 0.018 ps [PDG] – Fix in fit
)(
))(.(2
22
i
eii
r
krNr
one example VPDL bin
BD
TT MpLVPDL )/(
1)/( 0 k
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Preliminary result:
(B+)/(B0):1.093 0.021 0.022 (stat) (syst)
Syst. dominated by:
- time dependence of slow reconstruction eff. - relative reconstruction efficiency CY
- Br(B+ + D*- + X) - K-factors - decay length resolution differences D0 D*
The prelim. DØ meas. is one of the most precise results Not updated
Adding more data
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/Jb
ps (sys) 0.043 (stat) 217.0179.0
221.1 b
sd KJB /
Also did,
2D fit: Mass andLifetime (100)
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Summary of Λb results
World Average
1.229±0.080 ps
0.798±0.052
Theory: 0.90±0.05
World Average uses semi-leptonic modes
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ps (sys) 0.020 (stat) 098.0090.0
444.1
sB
Most existing meas. use SL mode
/JBs
Single best measurement
*/ KJBd
Also did,
2D fit: Mass andLifetime
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Summary of Bs results
World Average
1.461±0.057 ps
0.951±0.038
Theory: 1.00±0.01
<World> contains final states with different amts. of CP e-states
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2nd order weak transition
Mixing is high priority SB
S
dtd m
mV
ρ<0 disfavoured by current limit on Δms (>14.4/ps)
00SS
LS BqBpB
00SS
HS BqBpB
LHS MMm
HLS
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Bs CP =+1 & CP = -1 Lifetimes
B0sJ/ψ φ unknown mixture of CP =+1 & CP = -1 states
In Standard Model s/s may be as large as 0.1 ( )
Γs = ( ΓLight + ΓHeavy)/2 ; ΔΓs = ΓLight - ΓHeavy
In the case of untagged decay, the CP – specific terms evolve like:
CP - even: ( |A0(0)|2 + |A||(0)|2 ) exp( -ΓLightt)
CP - odd: |A┴(0)|2 exp( -ΓHeavyt)
Flavor specific final states (e.g. B0slDs ) provide:
Γfs = Γs - (ΔΓs)2 / 2Γs + Ό ( (ΔΓs)3 / Γs 2 )
sm
DZ – Beauty’03
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Bs Lifetimes, transversity variable θT
The CP-even and CP-odd components have different decay distributions.
The distribution in transversity variable θT and its time evolution is:
d(t)/d cosθT ∞ (|A0(t)|2 + |A||(t)|2) (1 + cos2θT) + |A┴(t)|2 2 sin2θT
3 linear polarization states: J/ψ and φ polarization vectors: longitudinal (0) to the B direction of motion;
transverse and parallel (||) and (┴ ) to each other
MC distributions for CP = +1 & CP= -1 for accepted events (D0)
DZ – Beauty’03
In progress
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)cos( tmPP
PPA s
MU
MU
How to measure Δm
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In search of BS oscillations
(“Amplitude method”)
)cos(12
tmAe st
P
Fit data to
Fit for A as a function of ms
Measurement: A = 1Sensitivity: 1.645A = 1 (95%)Limit: A < 1 - 1.645A (95%)
Current limit : ms > 14.4 ps-1 @95% CL
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Compare A for Δm=15 ps-1
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Significance of mixingmeasurement BS
Stm
eDN
2/2)(
2
2
We need:
Final State reconstructionAbility to measure B decay lengthB flavour at decay and production
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Use flavour-specific decays to get flavour of B at decay
To get flavour of B at production use
Flavour tagging
b-hadronTrigger leptonFragmentation
pionB
PV D
neutrino
Same side
Lxy
Soft lepton
Jet charge
Opposite side
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Require |Q| > 0.2
MC
b0Q (B+ MC)
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Data sample split into two sets:1) Tagged by soft muons (SLT)2) Tagged by combined jetQ+SST algorithm
Combined algorithm produces non-zero answer if:– Event not tagged by SLT– At least one of jetQ and SST gives a non-zero answer– jetQ and SST give same answer ( better dilution)
Combined tags analysis - Bd
200pb-1
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Combined tagger result
Simultaneous fit to SLT and jetQ+SST asymmetries
SLT
jetQ+SST
md=0.456 0.034 (stat) 0.025 (syst) ps-1
D0 = (44.8 5.1) % SLT D0 = (14.9 1.5) % jetQ+SST
D= (27.9 1.2) % jetQ+SST
= (5.0 0.2) % SLT = (68.3 0.9) % jetQ+SST
Preliminary results:
Chief systematics:• D* sample composition• D** pion tagging probability• Charged B dilution determination
200pb-1
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One can reconstruct in hadronic and semi-leptonic modes
Hadronic modes, e.g., Pros: Very good proper time resolution Cons: Low branching fraction ( ), triggers
Semi-leptonic modes, e.g., Pros: Large Branching fraction , triggers Use both Muon & Electron final states Cons: Poorer proper time resolution
SB
(*)SS DB
(*)SS DB
%5.0
%10
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X SS DB
SL modes have large yields
DS BR= (3.60.9)%
~ 9481 events in 250pb-1
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BS DS X
Other DS decays are being studied too
BR= (3.30.9)%(BR comparable to Ds )
But larger backgrounds D- K+ - -
D- K* - non-resonant D- K+ - -
~ 4933 events in 200 pb-1
Significant increase in total BS yield
KKDs0*
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μ+
π -
K+K-
φ
D-S
BS
μ+
Tagging muon Y, cm
X, cm
Mixed BS candidate in Run 164082 Event 31337864
Two same sign muons are detected Tagging muon has η=1.4 See advantage of muon system with
large coverage MKK=1.019 GeV, MKKπ=1.94 GeV PT(μBs)=3.4 GeV; PT(μtag)=3.5 GeV
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Studying electrons as an initial state flavour tag Hadronic modes – Bs -> Ds* pi
New triggers online – very effective for hadr. Decays
If nature is kind, and Δm is on the low side, we could have a shot at it with the SL mode
Some upgrades are planned: Layer 0 – new Silicon layer at r ~ 2.5 cm. Significant improvement in proper time resolution (mid-2005) Double trigger bandwidth/reconstruction farms and write more data to tape – in proposal stage
Progress report:
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Conclusions and Outlook
Lot of progress in the previous year
Accelerator performing reasonably well. Expect 500 pb-1 by the end of the calendar year
B physics group producing competitive results
Exciting times ahead
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Backup slides
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Elements of the CKM matrix can be written as: λ – Cabbibo angle (~0.22), A (~0.85),
Magnitude of CP violation is given by η
b
s
d
V
b
s
d
VVV
VVV
VVV
b
s
d
CKM
tbtstd
cbcscd
ubusud
ˆ
'
'
'
))2/1((, 2
Need to precisely determine the CKM matrix
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Unitarity of the CKM matrix leads to
relationship between various terms One such relation:
0*** tbtdcbcdubud VVVVVV
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CA:
BA:
If CKM matrix is unitary, leadsto triangles in the ρ, η planeVtd
Vub
Vcb
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Study of B hadrons yields B mixing: η can be inferred from CP violation Within the SM, CP conserving decays sensitive to
> 0 can be inferred from limit on Bs mixing
Complementary meas. of η, from New phenomena might affect K and B differently
,,|,/||,| tstdcbubcb VVVVVtstd VV ,
|||,/||,| tdcbubcb VVVV
|| tdV K
can tell if η is non-zero
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Winter 2004HFAG avg.(fit does not include results onSin(2β))
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SMT regionηmax = 2.5
SMT+ CFTηmax = 1.65
Pre-shower detectors help in e-ID
Barrels and Disks
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6 barrels: 4 layers SS+DS, 2/90° stereo |z|<0.6 m, r = 2.7-10 cm
12 central F disks: DS, 144 wedges, stereo
4 forward H disks: 96 wedges, z: 1.1/1.2 mr: 9.5-20 cm
15 5.7
Tracking to η ~ 3 (θ ~ 6°)
793K channels, rad hard to 1 MRad ~ 2-3 fb-1
S/N > 10, 1 MIP ~ 25 ADC countsHit resolution ~ 10μ
SMT
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• J/mass is shifted by 22 MeV• Observe dependence on Pt and on material crossed by tracks• Developed correction procedure based on field & material model • Finalizing calibration of momentum scale using J/Ks, D0
NOT yet used
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Track triggers very important for B physics - Trk/muon match at L1 - Trks are fed to L2 Silicon track trigger - Trk/Pre-shower match
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Silicon Track Trigger is being commissionedTrigger is online – as yet not used for physics
CFT inner layer
CFT outer layer
SMT barrels
1-mm road
Performs final silicon cluster filtering and track fitting– Lookup table used to convert
hardware (e.g., channel, etc.) to physical coordinates ( )
– 8 300-MHz 32-bit integer Texas Instruments DSPs perform a linearized track fit
– Fit using precomputed matrix stored in lookup table
0)( rr
br
,r
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Accelerator performance
Run Ib Run IIa Run IIb
# bunches 6X6 36X36 140X133
(TeV)1.8 1.96 1.96
1.6E31 8E31 2-5E32
Bunch x-ing(ns)
3500 396 132(?)
Int./x-ing 2.8 2.4 2-5
s12 scm L
Currently 12
inst scm31E64 L 1pb280LHave
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Basic Particles
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Inclusive B lifetime using X0 DB
112 - pbL μm)stat(25438c 2472PDG
Standard technique – no IP cuts. Poor S/B
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Aside: Where do the B’s go?
Factor # events for 2 fb-1
3E11
2 b quarks/event 6E11
6E10
1.8E8
7.2E6
3.6E6
Single μ Trig. Eff < 1%
<3.6E4
Reco. Eff. <10% <3.6E3
bbb 150)(
10.0)( (*) sBbB
003.0)( ss DBB
04.0)( sDB
5.0)( KKB FlavourTag μcomesfor free
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For L=1, get two pairs of degenerate doublets,
jq=1/2, J=0, 1 -
jq=3/2, J=1, 2 -
HQS also constrains the strong decays of these states
jq = 1/2 decay via S-wave, hence expected to be wide jq = 3/2 decay via D-wave, hence narrow
'*0 , BB
*21, BB
These four L=1 statesare collectively known as B** or JB
Strong decays
For L=0, two states withjq=1/2, J=0, 1 - B, B*
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Lessons from Charm (III)
For charm mesons, M(D*)-M(D) ~ 140-145 MeV For bottom, M(B*)-M(B) ~ 46 MeV Theory: Splitting within a doublet has 1/m_Q
corrections
M( )-M( ) ~ 32-37 MeV (jq=3/2 doublet)
Could expect this to be ~ 10-15 MeV for M( )-M( )
For non-strange charm, M(D**)-M(D) ~550-600 MeV
Would expect similar behaviour for B mesons
*2D 1D
*2B 1B
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Signal Reconstruction (V)
We fit the ΔM signal with 3 relativistic Breit-Wigner functions convoluted with Gaussians
N: Number of events in the three peaks : Fraction of in all events : Branching fraction of From theory fix and From MC fix resolution of ΔM=10.5 MeV
))),(*)1(),(*)(1(),(*.( 2322221111 GfGffGfN
**
2 BB 21 5.02 f
1f
2f1B
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Sample composition
B meson lifetimes and branching rates from PDGK-factor distributions, decay length resolution, reconstruction efficiencies from MC
86% B0
12% B+ 2% BS
16% B0 2% BS
82% B+
D* sample
D0 sample
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2D lifetime fits
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Quarkonia at D0
Have older results on J/Psi production. Will update - Cross-section as a function of pT and η
Started to look at Upsilon production characteristics - We presented a preliminary pT distribution at QWG’03 and more recently at PHENO’04 - Next step is to determine production absolute cross-section and polarization studies
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%d0%a4%d0%93%d0%9e%d0%a1%203 %20%d0%9b%d0%b5%d1%87%d0%b5%d0%b1%d0%bd%d0%be%d0%b5%20%d0%b4%d0%b5%d0%b
%d0%9d%d0%b0%d0%b2%d1%87%d0%b0%d0%bb%d1%8c%d0%bd%d0%be %d0%bc%d0%b5%d1%82%d0%be%d0%b4%d0%b8%d1%87%d0