Prospects on CP violation in the b sector at hadron colliders

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Prospects on CP violation in the b sector
at hadron colliders
Marta Calvi Università di Milano Bicocca and INFN
DAPHNE2004 Frascati 7th June 2004
Special thanks to F.Bedeschi G.Punzi for the
Tevatron part
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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

• 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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Why hadron colliders?
Huge bb cross section (100500 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 ee- 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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Tevatron performance

• Tevatron working very well this year
• Record luminosity 7.3 1031 sec-1 cm-1
• 300 pb-1 on tape
  200-250 pb-1 used for analysis so far
• RECYCLER had a first successful test
• CDF/D0 DAQ efficiency 85-90

FUTURE Luminosity goal 4.4-8.5 fb-1 by 2009 CDF
D0 designed for 132 ns will have to work
at 396 ns and 2.71032 sec-1cm-2
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CDF D0 in RUN II
New Silicon (SVT) tracking at trigger level
select high pT tracks from b, c with IP gt 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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The future LHCb and BTeV
Forward detectors
Accelerator parameters
LHCb BTeV ?s 14 TeV
2 TeV sbb 500
mb 100 mb sinelelastic
80 mb 50 mb L (cm2s-1)
2 ? 1032 2 ? 1032 Nbb/year
1012 2 ? 1011 t
bunch spacing 25 ns (132) 396
ns wbunch crossing 40 MHz (7.6)
2.5 MHz sz 5 cm
30 cm ltNpp int./bco gt 0.4
(2) 6
bb correlation
both b hadrons in acceptance
qb
b boost
bg
Long decay lenght
h
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LHCb
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LHCb trigger
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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BTeV
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BTeV Trigger
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 ? pp-
63 Bs ? DsK 74 B- ? DoK-
70 Bo ? Kg 40
Level 2
Secondary vertex
1/10
Full reconstruction
Level 3
Channel LVL1 eff() B ? pp- 55
Bs ? DsK 70 B- ? DoK-
60
1/2
Re-evaluation at 396 ns ltNgt6
200 MB/s on tape
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B Flavour Tagging
Opposite side lepton or K
JETQ
PV
Same side K or p
Expectations
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
?D2 LHCb B0 Bs
Muon 1.0 1.0
Electron 0.4 0.4
Kaon opp.side 2.4 2.4
Vertex Charge 1.0 1.0
Same side p / K 0.7 2.1
Combined 4.7 6.
LHCb results are channel dependent
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B0s B0s mixing - Semileptonic modes
High statistics, good S/N, but limited
resolution ? only moderate xs
Bs0? Ds- l n X (Ds-? fp -, f?KK-)
Ds
Ds
D
300 Ds?pp?
D
Yield / lumi 31 pb, just muons
D0 prospects 1.5 ? sensitivity up to Dms15ps-1
with 0.5 fb-1
Yield/lumi 7.6 pb muons elect.
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B0s B0s mixing - Hadronic modes
Fully reconstructed, best proper time resolution
can resolve fast oscillations.
Bs0? Ds- p (Ds-? fp-, f?KK- )
S/B 2 ?D2 4 ?t67
fs Yield/Lumi0.7 pb
Low statistics working on Bs?Dsppp and
Ds?KK/KsK/ppp
CDF prospects Yield/Lumi2. pb ?D2 5 ?t
50 fs 5? sensitivity to Dms18 ps-1 with 1.7
fb-1 5? sensitivity to Dms24 ps-1 with 3.2
fb-1
DsK
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B0s B0s mixing with Bs0 ? Dsp follow up
LHCb 80.000 events/yr
B/S0.32 Proper time s 33 fs
5? observation of Bs oscillation Dms 68 ps-1/
yr
xs reach of BTeV
5? observation of Bs oscillation up to xs80
ps-1 in 3.2 yr with Bs?Dsp
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Fs and ?Gs with B?s?J/? f

• The gold plated decay of Bs. Measure the weak
  phase of Vts (angle Fs)
• Expected to be small in SM Fs -2?
  -2?2? -0.04

• 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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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(Fs)) ? 0.1 with 2 fb-1
If asymmetry observed with 2fb1 ? signal for NEW
Physics
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Fs and ?Gs with B?s?J/?f(h) the future
LHCb 100 k Bs?J/y(??)f(KK) events/yr B/Slt0.3
20k J/?(ee) proper time s 38 fs
?(Fs) 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
3k Bs?J/?h CP autostates simpler
analysis ?(Fs) 2.8O (1 year)
Critical check
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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) 054009)
BsBd BRs alone provide, via U-spin simmetry,
informations of g (R. Fleischer hep-ph/0306270)
and checks of CKM model (MatiasLondon,
hep-ph/0404009)
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B?h?h? recostruction at CDF

• Bd???
• Bd?K?
• Bs?K?
• Bs?KK

MC
Separation of B0?hh-contributions in mass peak
Use dE/dx calibrated on D events
(K/p separation 1.4 ?) and
kinematics Mpp vs
(1-pmin/pmax)qmin
MC
MC
MC
MC
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B?h?h? Tevatron results and prospects
CDF (65 pb-1)
First evidence of Bs ?KK-
fsBR(Bs?KK) / fdBR(Bd?Kp) 0.740.20(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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More B?d ? ???? and B?s?K?K?
without RICH
Bd???-
Use of RICH detectors for excellent K/p separation
K/p separation
sM17 MeV
LHCb events / yr B/S B?????? 26 k
lt0.7 B??K?? 135 k
0.16 Bs?K?K? 37 k 0.31 Bs?K??
5.3 k lt1.3
BTeV events/ yr B/S
B?????? 15 k
0.33 B??K??? 62 k 0.05
?(A??) 0.03
time-dependent CP asymmetries ?(A??) 0.06
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? from B?d? ???? and B?s?K?K?
d vs ?
R. Fleischer, Phys. Lett. B459 (1999) Use
B?????? and Bs?K?K? and exploit U-spin flavour
symmetry d d and ? ?
fake solution
68 and 95 CL regions
Adir (B0? ??-) f1(d, ?, ?) Amix(B0?
??-) f2(d, ?, ?, ?d) Adir (Bs?KK? )
f3(d, ?, ?) Amix(Bs?KK? ) f4(d, ?, ?, ?s)
B?????? (95CL)
Bs?K?K? (95CL)

Use Fs (Bs?J/??), Fd(B0?J/?Ks) ? can solve
for g
?(?) 4?6 deg (1 year)
(?input 65º)
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? 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
7500 events / yr B/S 0.14
BTeV
LHCb
5400 events/ yr B/Slt1.0
?ms (ps-1 ) 20 25 30
?(?Fs) 140 160 180
?20lt ?T1/T2lt 20
?(?Fs) 80
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? 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
A ( B?? DCPK? ) A3 /?2 1/?2 ( A(B??
D0K?) A(B?? D0K? ) ) 1/?2 ( A1
A2 ei (??) )
with B?? D0K0 self-tagged through K0? Kp -
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
?(?) 7?8 deg
for 55 lt ? lt 105 deg ?20 lt ? lt 20 deg
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b ? s penguin decays
ACP in Bd ? fKs measured at BaBar and Belle
hints of possible NP ?
Several channels accessible at hadron colliders
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 BRs) 800 Bd ? fKs
B/S lt1.3 1200 Bs ? ff B/S lt0.4 9300
Bs ? f g B/S lt2.4
BR(Bs?ff) (1.40.6(stat)0.2(syst)0.5(BRs))10-
5
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a from B??r? ? ?p-??
B ? rp-
s(Mgg)3.7?0.3 MeV
Time dependent analysis of Dalitz plot to get a
independently from penguin contributions
BTeV
Bo?rp- 5.4 k events/yr S/B 4.1 Bo?ropo
0.8 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 0.2 77.2o 1.6o
77.3o 0.4 0 77.2o 1.8o
93.0o 0.2 0.2 93.3o 1.9o
111.0o 0.2 0.2 111.7o 3.9o
resonant non-rp bkgrd
non-resonant non-rp bkgrd
da 2o- 4o in 2 years
ainput77.3o
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B0 ? K0 ??-
Sensitivity to New Physics in
Standard Model BR(B0?K??-)(1.2?0.4)x10-6
determination of Vts complementary to Dms/Dmd
oscillation measurements
??- invariant mass distribution
??- forward-backward asymmetry
AFB(s)
Annual yield (SM) 4.4k B/S lt2 ?(BR) 3
?(ACP) 3
LHCb
Annual yield (SM) 2.5 k B/S0.1
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Event Yield (untagged)
LHCb BTeV
Channel Yield B/S Parameter Yield B/S parameter
B0 ? pp- 26 k lt 0.7 s(A)0.06 15k 0.33 s(A)0.03
Bs ? K K- 37 k 0.3 g5º 19k 0.15
B0 ? K p- 135 k 0.16 62k 0.05
Bs ?Ds-p 80 k 0.3 59k 0.33
Bs ?Ds-K- 5.4 k lt 1.0 gFs14º 7.5k 0.14 gFs8º
B0 ? D0 K0 4.5 k 0.3 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 26 k 1.0
Bs ?J/y(m-m )f 100 k lt 0.3 Fs3.6º
Bs ?J/y(e-e )f 20 k 0.7
Bs ?J/y(m-m )h 7 k lt 5 2.8k 0.07 Fs2.8º
Bs ?J/y(m-m )h? 9.8k 0.03
B0 ??? 10.8 k lt 3 6.2k 0.24 a4º
B0 ?K0 g 35 k lt 0.7 s(A)0.01
B0 ?K0 mm 4.4 k lt 2.0 2.5k 0.09
B0 ??KS 800 lt 1.3
Bs ? mm 17.2 5.7 5.7 7.7
1 year (107s) at L 2x1032 cm-2 s-1
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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

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Back up
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Branching Ratios
BR(B0 ? pp-) (4.4?0.9) x10-6 PDG2002
BR(B0 ? K p- ) (1.74?0.15) x10-5 PDG2002
BR(Bs ? K K- ) (1.74?0.15) x10-5 BR(B0?K p- )
BR(Bs ? p K-) (4.4?0.9) x10-6 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 ? pp-p0) 2. x10-5
BR(Bs ? J/y f ) (9.3?3.3) x10-4 PDG2002
BR(B0? K0 g ) (4.3?0.4) x10-5 PDG2002
BR(B0? fK0 ) (8.1?3.) x10-6 PDG2002
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 Ali
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Triggering bs (and cs) at Tevatron
conventional
new approach
Di-lepton CDF and DØ B ? charmonium Rare B ?
mm Two muons with pTgt 1.5 GeV hlt 1 pTgt
2.5-4.5 GeV h lt2
electron or muon and displaced track CDF
only Semileptonic decays Electron (m) with
pTgt 4 (1.5) GeV hlt 1 and one track
with pT gt 2.0 GeV IP gt 120 mm
Two displaced tracks CDF only n-body hadronic
B Two tracks with pT gt 2.0 GeV SpT gt 5.5 GeV
IP gt 120 (100) mm
Single-muon DØ only Semileptonic decays One muon
with pT gt 2 - 4 GeV h lt2
Displaced track trigger at Level2 the door to B
physics.
Also rare B decays with
high S/B