Title: b
1?.?. ???????? (????)
b ?????? ?? LHCb
????????? ?????? ??????? CP ????????
2- LHCb forward spectrometer (running in pp
collider mode) - Data taking starts next year
- Expect 10 fb-1 by 2013
- B physics is also a part of the ATLAS and
CMS early program - LHCb is designed to run at an average
luminosity of 2 ?1032 and be able to - handle 5?1032 cm-2s-1 for short periods
- For a nominal year of 107 seconds this
corresponds to 2 fb-1 . Most physics - goals are expressed in terms of the reach for 10
fb-1 (i.e. 5 nominal years) - Super LHCb (SLHCb) will run at 10 times
- the initial design luminosity with twice
more efficient trigger - and record data sample of gt 100 fb-1
- Start data taking after 2014
- Working Group set up to identify the RD
required to make an upgrade of LHCb feasible, - and to make the physics case
- Issues of triggering, fast vertex detection,
electronics, radiation dose, handling the pile-up
and higher occupancy, etc
3 LHCb Collaboration
- LHCb is a collaboration of 670 members from 48
institutes - in Brazil, China, France, Germany, Ireland,
Italy, Poland, Romania, Russia, Spain,
Switzerland, Ukraine, UK, and the US
?????????? ????????? ????(??????),
????(????????), ???(??????), ????(???????),
???(???????????) ?????? ???????????? ????? ?
???????? ????????????????? ??????? ? ????????
????????? ??????????? ?????????? ? ????????????
????? ???
4The LHCb Experiment
- Forward geometry
- Running with less focused
- beam is sufficient
- At 2?1032 1012 bb pairs
- are produced per year
p
Dipole magnet
Interaction point
p
5 Experimental infrastructure
Shielding wall(against radiation)
Most detectors open transversely for access
Electronics CPU farm in barracks (Control Room
on surface)
Offset interaction point To maximize space
6Shielding wall
Labour intensive Egyptian work as inaccessible
by crane
- Assembly of lower part is progressing
wellPaused while a problem with leaking
cooling-water pipes is investigated
7Calorimeters
Magnet
Muon detector
RICH-2
OT
RICH-1
VELO
Its full! Installation of major structures is
essentially complete Commissioning is ongoing !
8UT as a standard approach to test the consistency
of SM
Mean values of angles and sides of UT are
consistent with SM predictions
- Accuracy of sides is limited by theory
- Extraction of Vub
- Lattice calculation of
- Accuracy of angles is limited
- by experiment
- 13
- b 1
- 25
9Search for NP comparing observables measured in
tree and loop topologies
?(pengtree) in B???,??,?? ?(pengbox) in
B??Ks ?(pengbox) in Bs???
- ?(treebox) in B? J/?Ks
- ?(tree) in many channels
- ?(treebox) in Bs? J/??
New heavy particles, which may contribute to d-
and s- penguins, could lead to some phase shifts
in all three angles ??(NP) ?(pengtree) -
?(tree) ??(NP) ?(B??Ks) - ?(B?J/?Ks) ?
0 ??(NP) ?(Bs???) - ?(Bs?J/??)
10Search for NP comparing observables measured in
tree and loop topologies
- Contribution of NP to processes mediated by loops
- (present status)
- to boxes
- ? vs Vub / Vcb is limited by theory (10
precision in Vub) (d-box) - ? not measured with any accuracy
(s-box) - to penguins
- ?(??(NP)) 30
(d-penguin) - ?(??(NP)) 8
(s-penguin) - ?(??(NP)) not measured
(s-penguin) - PS ??(NP) ?? (NP)
- ??(NP) measured in B??? and B???
decays may differ depending - on penguin contribution to ?? and
?? final states
11? LHC prospects
Bs ?J/?? is the Bs counterpart of B0?J/? KS
- In SM ?S - 2arg(Vts) - 2?2? - 0.04
- Sensitive to New Physics effects in the Bs-Bs
system if NP in mixing ? ?S ?S(SM)
?S(NP) - 2 CP-even, 1 CP-odd amplitudes, angular analysis
needed to separate, then fit to ?S, ??S, CP-odd
fraction - LHCb yield in 2 fb-1 131k, B/S 0.12
LHCb
0.021
0.021
ATLAS
will reach s(?s) 0.08 (10/fb, ?ms20/ps, 90k
J/?? evts)
12UT angle g LHCb (BaBAr BELLE Tevatron
12 precision for ? at best)
- Interference between tree-level decays
Vcs Vub suppressed
Favored Vcb Vus
u
s
Common final state
K()-
K()-
s
u
u
b
B-
B-
b
c
c
u
D()0
D()0
u
u
f
Parameters ?, (rB, dB) per mode
- Three methods for exploiting interference (choice
of D0 decay modes) - (GLW) Use CP eigenstates of D()0 decay, e.g.
D0 ? K K- / pp , Ksp0 - (ADS) Use doubly Cabibbo-suppressed decays,
e.g. D0 ? Kp - - (Dalitz) Use Dalitz plot analysis of 3-body D0
decays, e.g. Ks p p-
- Mixing induced CPV measurement in Bs ? Ds K
decays - Specific for LHCb
13B ? D(KSpp-) K
- Mode used by B factories to give best existing
constraint on CKM angle g
Simulated data for LHCb (1 year)
(stat, syst, model)
- 400 events each
- LHCb yield 5000 events/2 fb-1
- Spot the difference between the Dalitz plots for
B and B- ? effect of CP violation - Binning can reduce model dependencePrecision on
g 12º (in one year)
14Model-independent approach
angle ? ( ?3 ) at SFF
A.Bondar, A.Poluektov Eur.Phys.J C47,347(2006)
hep-ph/0510246
- 50 ab-1 at SFF factory
- should be enough for
- model-independent ?/f3
- measurement with accuracy
- below 2
- 1fb-1 at ?(3770) corresponds
- 2100 CP-tagged KS?? - events
- (first estimation based on CLEO-c
- data by David Asner)
- 10 fb-1 at ?(3770) needed to
- accompany SuperB measurement
15UT angle g LHCb summary table
Combined precision after 2 fb-1 ?(?) ? 5? (from
tree only)
16LHCb (10fb-1 ) and SFF (50-75 ab-1) SLHCb (gt100
fb -1) sensitivities
Channel Yield Precision
? From tree channels ?(?) lt 3?
? Bd ???-?0 B ? ??0, ??-,?0?0 70k 45k,10k,5k ?(?) lt 4?
? Bd ? J/?(??)KS Bd ? ?KS 1200k 4k ?(sin2?) lt 0.01 ?(sin2?) 0.1
?s Bs ? J/?(??)? Bs ? ?? 750k 20k ?(?s) 0.01 ?(?s) 0.05
LHCb
SFF SLHCb
SLHCb (stat. only) 0.003 lt 1?
(Bs?DsK) - - -
gt 2014
S(?K0S) 0.02-0.03 S(??) 0.01
17Search for New Physics in Rare Decays
- Exclusive b ? s?
- B?K??
- Bs???
- B ? tn, hnn, ...
- B ? s?, sll inclusive
We are just approaching sensitivity promising
for discovery
LHCb
SFF
Experimental challenge keep backgrounds under
control
18b ? s? exclusive
Bs? ?? BELLE observed 168 events 2 weeks run at
?(5S) no TDCPV
LHCb control channel Bd ? K? 75k signal
events per 2fb-1
LHCb annual yield 11k with B/S lt 0.6
19b ? s? exclusive
b ? ? (L) (ms/mb) ? ?(R)
- Measurement of the photon helicity is very
sensitive test of SM - Methods
- Mixing induced CP asymmetries in Bs ? ?? ,
B?Ks ?0? - Photon helicity can be measured directly in
radiative B decays to final state with ? 3
hadrons. - Promising channels for LHCb are B? ?K? and B?
K??? decays
Expected yield per 2 fb-1 BR(B ? K?-??) 2.5
? 10-5 rich pattern of resonances
60k BR(B ? K??) 3 ? 10-6 highly
distinctive final state 7k
20b ? s? exclusive
- Mixing induced CP
asymmetries - B?Ks?0 ? (B-factories)
S - (2O(?s))sin(2?)ms/mb (possible
contribution from b?s?g) - 0.022 0.015
P.Ball and R.Zwicky hep-ph/0609037 Present
accuracy S -
0.21 0.40 (BaBar 232M BB)
S - 0.10 0.31 (BELLE 535M BB)
LHCb sensitivity with 10fb-1 ?(A?) 0.09
21B ? K??
In SM this b?s penguin decay contains
right-handed calculable contribution but this
could be added to by NP resulting in modified
angular distributions
SM
22B ? K?? LHCb prospects
- Forward-backward asymmetry AFB (s) in ??-
- rest frame is a sensitive NP probe
- Predicted zero of AFB (s) depends on Wilson
- coefficients C7eff / C9eff
- 7.2 k events / 2fb-1 with B/S 0.4
- After 10 fb-1zero of AFB located to 0.28
- GeV2 providing 7 stat. error
- on C7eff / C9eff
- Full angular analysis gives better
- discrimination between models. Looks
- promising
23Bs ? ??
Very smal BR in SM (3.4 0.5) x 10-9
This decay could be strongly enhanced in some
SUSY models.
Current limit from CDF BR(Bs???) lt 47?10-9
(20?10-9 expected final D0CDF limit) With loose
selection LHCb expects 40 signal events
(2fb-1/SM BR) on top of 1500 background events
(mostly form b? ? , b?? ) Particle ID, vertexing
and invariant mass resolution ?(M ?? ) 18 MeV
provide excellent separation of signal from
background
24OUTLOOK
Clean experimental signature of NP is unlikely at
currently operating experiments
- From now to 2014
- A lot of opportunities (LHCb will start data
taking next year) - Important measurements to search for NP and test
SM in CP violation - ? if non-zero ? NP in boxes lt 2010
- ? vs Rb and ? vs Rt (Input from theory !)
- ??(NP) and ??(NP) if non-zero ? NP in
penguins - in Rare decays
- BR(Bs ? ??) down to SM prediction lt 2010
- Photon helicity in exclusive b?s? decays
- FBA transversity amplitudes in exclusive
b?sll decays lt 2010
After 2014 ATLAS and
CMS might or might not discovered New Particles.
At the same time LHCb might or might not see NP
phenomena beyond SM. In either case it is
important to go on with B physics at SFF
Upgraded LHCb Need much improved precision
because any measurement in
b-system constrains NP models
high pT
Bs
25LHCb calorimeter system
- Scintillating Pad Detector / PreShower
- Electromagnetic Calorimeter
- Hadron Calorimeter
- Fast response within 25 ns
- is a 1st priority requirement for L0 trigger
- All 3 calorimeter are using the
- same technology absorber/scintillator
- readout with WLS fibres
Front of PS
Back of SPD
Lead
26Overview of LHCb SPD and PS
Inner Middle Outer
Modules
PSSPD built from 16 super modules
Side view of upper part
Super module with 2 x 13 modules
Scintillator coiled fiber
Moving cable trays
Super module frame
- TDR estimations (2000)
- outer 20 ph.el.
- inner 30 ph.el.
MAPMT VFE
R/O cables
Preshower cosmic test before Super-Module
installation phe/MIP for each
tile Inner 25 phe Middle 29 phe Outer 19 phe
27Overview of LHCb ECAL
3312 shashlik modules with 25 X0 Pb
Two halves on chariots and electronics platform
on top
Inner module
Fibres with loops
Middle module
Outer module
Electron. platform
modules
Scintillators, lead-plates, covers
PMT and CW base
Beam plug
Front- cover
PMT
End- cover
Chariot
CW base
TYVEK
Scintillator
Lead plate
28Overview of LHCb HCAL
52 modules with longitudinal tiles
Electron. platform
modules
Beam plug