1. Prospects on CP violation in the b sector at hadron colliders
Marta Calvi
Università di Milano Bicocca and INFN
DAPHNE2004 Frascati th June 2004
Special thanks to F.Bedeschi & G.Punzi for the Tevatron part
DAPHNE M. Calvi

2. Unitarity Triangles
B decays offer great opportunities to test the SM paradigm of quark mixing and CPV, but also to discover signals of NEW Physics
Bd0  p+ p-
Bd0  r p
BS0  DSK
Bd0  DK*0
Bd0  D*p
B 0  h h
BS0  DS p
Bd0  J/y KS0 Bd0  F KS0
BS0  J/y F, BS0  J/y h()
Overconstrain the Unitarity Triangles
Measure of several CP phases, in different channels
Access to rare decays dominated by penguins and box diagrams
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3. Experimental requirements
Why hadron colliders?
Huge bb cross section (100–500 mb wrt ~1nb at Y(4S) ) Access to all b-hadrons: Bd,u, Bs, b-baryons and Bc
Presence of underlying event
High tracks multiplicity
b produced with wide range of momentum (no beam constraints as for e+e- colliders)
High rate of background events
The challenge
Trigger ! (also fully hadronic decays) Excellent tracking and vertexing Excellent PID
Experimental requirements
Mass resolution Proper time resolution Exclusive b decays
The present and near future: CDF & D0 at TEVATRON
LHCb at LHC (startup in 2007)
BTeV at TEVATRON (startup in 2009)
Next generation:
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4. Tevatron performance Tevatron working very well this year
Record luminosity = 7.3 ×1031 sec-1 cm-1
~ 300 pb-1 on tape ~ pb-1 used for analysis so far
RECYCLER had a first successful test
CDF/D0 DAQ efficiency ~ 85-90%
FUTURE
Luminosity goal fb-1 by 2009
CDF & D0 designed for 132 ns will have to work at 396 ns and ~2.7×1032 sec-1cm-2
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5. CDF & D0 in RUN II
New Silicon (SVT) tracking at trigger level: select high pT tracks from b, c with IP > 120 (100) mm (first IP trigger at hadron collider!)
Upgraded tracking: COT, 7-8 Si layers tracker
New Time of Flight: some hadron PID
New 2T super conducting Magnet
New 8 layers (fiber) tracker
New Silicon tracker trigger (displaced vertices) coming soon
Improved muon coverage
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6. The future: LHCb and BTeV
Forward detectors
Accelerator parameters:
LHCb BTeV
s TeV TeV
sbb mb mb
sinelelastic mb mb
L (cm–2s-1)   1032
Nbb/year  1011
t bunch spacing ns (132) 396 ns
wbunch crossing MHz (7.6) 2.5 MHz
sz cm cm
<Npp int./bco > (2) 6
bb correlation
both b hadrons in acceptance qb qb
b boost
BTeV bg
Long decay lenght h
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7. LHCb
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8. LHCb trigger L0 efficiency L1 efficiency Total L0L1 efficiency 40 MHz
Level-0
Level-1
HLT
40 MHz
1 MHz
40 kHz
200 Hz
high pT m, e, g, hadrons (~1-3 GeV) Pile-up veto
high impact parameter, high pT tracks (extrapolation VELO-TT )
software trigger on complete event
L0 efficiency
L1 efficiency
Total L0L1 efficiency
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9. BTeV
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10. BTeV Trigger Level 1 Channel LVL1 eff(%) B  p+p- 63 Level 2
Input 2.5 MHz
Vertex trigger
track and vertex finding in pixels cut on number of detached tracks
Level 1
+ muon trigger
1/100
Channel LVL1 eff(%)
B  p+p
Bs  DsK
B-  DoK
Bo  K*g
Level 2
Secondary vertex
1/10
Level 3
Full reconstruction
Channel LVL1 eff(%)
B  p+p Bs  DsK
B-  DoK
1/2
Re-evaluation at 396 ns <N>=6
~ 200 MB/s on tape
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11. B Flavour Tagging m JETQ DØ D2 [%] Expectations
Opposite side lepton or K
JETQ m
B0signal
B0opposite D p+ p- K-
N/A
in progress
Same side kaon
3.3  1.7
Jet charge
Opp. side kaon
5.5  2.0
1.9  0.9
Same side pion
Soft electron
1.0  0.2
0.7  0.1
Soft muon DØ
D2 [%] PV b s u Bs K+
Same side K or p
Expectations
D2 [%] LHCb B0 Bs
Muon
1.0
Electron
0.4
Kaon opp.side
2.4
Vertex Charge
Same side p / K
0.7
2.1
Combined
~4.7
~6.
eD2 [%] BTeV B0 Bs
Muon
1.2
1.3
Electron
0.8
0.9
Kaon opp. side
6.0
5.8
Jet Charge
4.8
4.5
Same side  / K
1.8
5.7
Combined
10.0
13.0
LHCb: results are channel dependent
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12. B0s B0s mixing - Semileptonic modes
High statistics, good S/N, but limited resolution  only moderate xs
Bs0 Ds- l+ n X (Ds- fp -, fK+K-) Ds Ds D+
+300 Dspp D+
Yield / lumi ~ 31 pb, just muons
D0 prospects: 1.5  sensitivity up to Dms=15ps-1 with 0.5 fb-1
Yield/lumi ~ 7.6 pb muons & elect.
DAPHNE M. Calvi

13. B0s B0s mixing - Hadronic modes
Fully reconstructed, best proper time resolution: can resolve fast oscillations.
Bs0 Ds- p+ (Ds- fp-, fK+K- )
Dsp
D*sX and others
S/B ~ D2 = 4% t=67 fs
Yield/Lumi=0.7 pb
Low statistics: working on BsDsppp
and DsK*K/KsK/ppp
CDF prospects
Yield/Lumi=2. pb D2 = 5% t =50 fs
5 sensitivity to Dms=18 ps-1 with 1.7 fb-1
5 sensitivity to Dms=24 ps-1 with 3.2 fb-1
DsK
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14. B0s B0s mixing with Bs0  Dsp : follow up
LHCb events/yr B/S= Proper time s =33 fs
Expected unmixed Bs Ds sample in one year of LHCb data taking (fast MC)
5 observation of Bs oscillation: Dms= 68 ps-1/ yr
xs reach of BTeV 6 5 4 3 2 1
5 observation of Bs oscillation up to xs=80 ps-1 in 3.2 yr with BsDsp
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15. Fs and Γs with BsJ/ f
The “gold plated” decay of Bs. Measure the weak phase of Vts (angle Φs)
Expected to be small in SM: Φs = -2 = -22 ~ -0.04 NP
B0s ?
High sensitivity to NEW Physics contributions in Bsmixing
Complicated analysis: PS  VV decay
3 contributing amplitudes
2 CP even, 1 CP odd
 fit angular distribution of decay states as function of proper time.
Derive also DGs= G(BsL) - G(BsH )
( SM expect. DGs/ G~ 0.10 )
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16. Bs  J/y (mm) f (KK) at Tevatron
Yield 176 16 in 180 pb-1
Yield 40328 in 225 pb-1
CDF reach: s(sin(Φs))  0.1 with 2 fb-1
If asymmetry observed with 2fb–1  signal for NEW Physics
DAPHNE M. Calvi

17. Fs and Γs with BsJ/f(h) : the future
LHCb: 100 k BsJ/y()f(KK) events/yr B/S< k J/(ee)
proper time s = 38 fs
(Φs) ~ 3.6O (1 year)
If DG / G ~ 0.1 can do a 5 s discovery in one year
BTeV: 10k Bs  J/h' events/yr k BsJ/h
CP autostates: simpler analysis
(Φs) ~ 2.8O (1 year)
Critical check:
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18. Bhh charmless decays
Bd, BdK, BsK, BsKK
“Tree”
“Penguin”
/K
/K
Bd/s
Bd/s
/K
/K
Direct CPV
CPV in mixing
dir
mix
Bd   , Bs  KK ACP(t) = ACP cos(md,s t) + ACP sin(md,s t)
Bd  K , Bs  K ACP = (N+ - N-) / (N+ + N-)
dir
Time dependent ACP in Bdpp and BsKK measure g independently of penguin pollution
(Fleischer and Matias: PRD66 (2002) )
Bs+Bd BRs’ alone provide, via U-spin simmetry, informations of g (R. Fleischer hep-ph/ ) and checks of CKM model (Matias&London, hep-ph/ )
DAPHNE M. Calvi

19. Bhh recostruction at CDF
Bd
BdK
BsK
BsKK MC
Separation of B0h+h-contributions in mass peak
Bdpp
BdKp
BsKK
BsKp _  K
Use dE/dx calibrated on D* events (K/π separation 1.4 )
and kinematics: Mpp vs (1-pmin/pmax)qmin MC MC MC MC
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20. Bhh Tevatron results and prospects
CDF (65 pb-1)
First evidence of Bs K+K-
fs·BR(BsKK) / fd·BR(BdKp) = 0.74±0.20(stat) ±0.22(syst)
Direct ACP(BdKp) = 0.02 ± 0.15(stat) ± 0.02(syst)
BR(Bd pp)/BR(Bd Kp) = 0.26 ± 0.11(stat) ± 0.06(syst)
Consistent with B-factories result
Update with current 180 pb-1 sample: ACP(Kp) to 7%, BR(BsKK) to 15%
Longer time-scale:
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21. More Bd   and BsKK
without RICH
Bd+-
Use of RICH detectors for excellent K/p separation
K/p separation
sM=17 MeV
LHCb events / yr B/S
B k <0.7 BK+ k
BsKK k BsK k <1.3
BTeV events/ yr B/S B k BK k
(A) ~ 0.03
time-dependent CP asymmetries
(A) ~ 0.06
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22.  from Bd  and BsKK
R. Fleischer, Phys. Lett. B459 (1999)
Use B and BsKK and exploit U-spin flavour symmetry
d = d’ and  = ’
d vs 
“fake”
solution
68% and 95% CL regions
Adir (B0 +-) = f1(d, , ) Amix(B0 +-) = f2(d, , , d)
Adir (BsK+K ) = f3(d’, ’, ) Amix(BsK+K ) = f4(d’, ’, , s)
B (95%CL)
BsKK (95%CL)
Use Φs (BsJ/), Φd(B0J/Ks)  can solve for g
() = 46 deg (1 year)
(input = 65º)
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23. Time dependent BsBs asymmetries
 from BsDsK
Measure   Fs from time-dependent rates: BsDsK and BsDsK (+CP conjugates)
Use Fs from BsJ/F
Model independent analysis  g indep. on NP
BsDsK
Time dependent BsBs asymmetries
BsDs
Need excellent PID for K/p separ.
5 yrs of data, ms= 20 ps -1
BTeV
7500 events / yr B/S:
LHCb:
5400 events/ yr B/S<1.0
ms (ps-1 ) 20 25 30
(+Φs)
140
160
180
20< T1/T2< 20
(+Φs) ~ 80
DAPHNE M. Calvi

24.  from B DK* and B DK*
Theoretically clean determination of g Similar to B± DK± but less squashed triangles (no color suppression)
Dunietz variant of the Gronau-Wyler method:
A1 = A1 A3 A4 A2 2
  
A ( B DCPK* ) = A3 /2 =
1/2 ( A(B D0K*) + A(B D0K* ) )
1/2 ( A |A2| ei (+) )
with B D0K*0 self-tagged through K*0 K+p - and DCP KK, pp
LHCb 1 year
yield
B/S
B D0 (K+) K*(K+)
3500
0.5
B DCP (KK) K* (K+)
550
3.9
Variant of the Gronau-Wyler method as proposed bt I.Dunietz:
Amplitude triangles are not as squashed as in case of B+/- -> DK+/-
Difficulty: also detect the D0 CP eignestate Dcp
() = 78 deg
for 55 <  < 105 deg
20 <  < 20 deg
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25. b  s penguin decays
ACP in Bd  fKs measured at BaBar and Belle hints of possible NP ?
Several channels accessible at hadron colliders:
5 significance
Bsff
Bd  fKs, Bd  fK*, B+ fK+
Bs  f f , Bs  r0f , Bs  fg , Bs  KK , Bs  K f …
Analyses ongoing in CDF.
LHCb: one year (SM BR’s)
~ 800 Bd  fKs B/S <1.3
~ 1200 Bs  ff B/S <0.4
~ 9300 Bs  f g B/S <2.4
BR(Bsff) = (1.4±0.6(stat)±0.2(syst)±0.5(BRs))×10-5
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26. a from Br  +p- BTeV
s(Mgg)=3.70.3 MeV
Time dependent analysis of Dalitz plot to get a independently from penguin contributions
BTeV
Bor+p k events/yr S/B = 4.1 Boropo k events/yr S/B = 0.3
Fit including resonant and non-resonant backgr. with 1000 tagged events (2 years)
minimum c2
a (gen)
Rres
Rnon
a (rec.) da
77.3o
0.2
77.2o
1.6o
0.4
1.8o
93.0o
93.3o
1.9o
111.0o
111.7o
3.9o
non-resonant
non-rp bkgrd
resonant
non-rp bkgrd
da ~2o- 4o in 2 years
ainput=77.3o
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27. B0  K*0 +- Standard Model BR(B0K*+-)=(1.20.4)x10-6
determination of |Vts| complementary to Dms/Dmd oscillation measurements
Sensitivity to New Physics in:
+- invariant mass distribution
+- forward-backward asymmetry
AFB(s)
Annual yield (SM): k B/S <2
(BR) ~ 3% (ACP) ~ 3%
LHCb
Annual yield (SM): 2.5 k
B/S=0.1
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28. Event Yield (untagged)
LHCb
BTeV
Channel
Yield
B/S
Parameter
parameter
B0  p+p-
26 k
< 0.7
s(A)~0.06
15k
0.33
s(A)~0.03
Bs  K+ K-
37 k
0.3
g~5º
19k
0.15
B0  K+ p-
135 k
0.16
62k
0.05
Bs Ds-p+
80 k
59k
Bs Ds-+K+-
5.4 k
< 1.0
g+Fs~14º
7.5k
0.14
g+Fs~8º
B0  D0 K*0
4.5 k
g ~8º
B0 J/y(m-m+)KS
216 k
0.8
s(A)~0.022
168k
0.10
s(A)~ 0.017
B0 J/y(e-e+ )KS
1.0
Bs J/y(m-m+ )f
100 k
< 0.3
Fs~3.6º
Bs J/y(e-e+ )f
20 k
0.7
Bs J/y(m-m+ )h
7 k
< 5
2.8k
0.07
Fs~2.8º
Bs J/y(m-m+ )h
9.8k
0.03
B0 
10.8 k
< 3
6.2k
0.24
a~4º
B0 K*0 g
35 k
s(A)~0.01
B0 K*0 mm
4.4 k
< 2.0
2.5k
0.09
B0 KS
800
< 1.3
Bs  mm
17.2
5.7
7.7
Event Yield (untagged)
1 year (107s) at L = 2x1032 cm-2 s-1
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29. Conclusions
Several results on B physics coming from Tevatron, soon a significant contribution to CKM understanding
Future experiments at hadron colliders will offer the opportunity to study many B-meson decay modes with high statistics.
precise determination of the CKM parameters through phase measurements
spot New Physics by overconstraining the Unitarity Triangles and measure rare decays
The goal will be reached thanks to:
dedicated triggers
excellent mass and decay-time resolution
excellent particle identification capability
DAPHNE M. Calvi

30. Back up
DAPHNE M. Calvi

31. Branching Ratios BR(B0  p+p-) (4.40.9) x10-6 PDG2002 BR(B0  K+ p- )
BR(Bs  K+ K- )
= BR(B0K+ p- )
BR(Bs  p+ K-)
= BR(B0 p+ p- )
BR(Bs Ds- p+ )
(3.00.4) x10-3
= BR(B0D-p+ )
BR(Bs Ds K)
(2.50.6) x10-4
calcolato
BR(B0  p+p-p0)
2. x10-5
BR(Bs  J/y f )
(9.33.3) x10-4
BR(B0 K0* g )
(4.30.4) x10-5
BR(B0 fK0 )
(8.13.) x10-6
BR(Bs ff )
5.2 x10-6
BR(Bs  mm)
3.5 x10-9
Ali
BR(B0 K0* mm)
(1.20.4) x10-6
DAPHNE M. Calvi

32. Triggering bs’ (and cs’) at Tevatron
conventional
new approach
Di-lepton
CDF and DØ
B  charmonium Rare B  mm
Two muons with:
pT> 1.5 GeV |h|< 1
pT> GeV |h |<2
electron or muon and displaced track
CDF only
Semileptonic decays
Electron (m) with:
pT> 4 (1.5) GeV |h|< 1
and one track with:
pT > 2.0 GeV IP > 120 mm
Two displaced tracks
CDF only
n-body hadronic B
Two tracks with:
pT > 2.0 GeV
SpT > 5.5 GeV
IP > 120 (100) mm
Single-muon
DØ only
Semileptonic decays
One muon with:
pT > GeV |h | <2
Displaced track trigger at Level2: the door to B physics Also rare B decays with high S/B
DAPHNE M. Calvi