Post on 06-Feb-2018
The CKM Picture
●CKM triangle has been (over)constrained in experiments such as BaBar, Belle,CLEO the Tevatron and others ●Very successful description of CP violation
New Physics in B mixing?
B_d mixing SM like, expected since tree decay
B_s mixing less constrained (small in SM)
The angle βs with Bs → J/ψφ
Golden Decay Channel for LHC• Bs → J/ψφ is strange counterpart of Bd → J/ψK0
• Cannot be done at Belle/BaBar
Complicated analysis• final state has two vector mesons, a mixture of CP-even (S
and D waves) and CP-odd (P wave) eigenstates, need angular analysis
SM prediction small:
s=−2s=−22=−2.05°
The angle βs with Bs → J/ψφ
CDF: [PRL 100 (2008) 161802]
First βs tagged analyses from Tevatron
D0: arXiv:0802.2255
Global analysis based on Tevatron results
βs reach with 2009 data
Would contradict MFV hypothesis
Another interesting channel, has no tree level contribution
GIM suppression leads to
→ theoretically clean& one-loop effect → good NP observable
In SM:
And
BaBar and Belle get a negative value:
2.7 sigma deviation,
A ss s=P c−P tV cbV cs∗Pu−P sV us∗V ub
1−As ss/ As ssO 2
ℑB−K s=sin2
B−J /K s−B−K sO 2
sin 2K s=−0.39±0.41
b→sss
B_s→ΦΦ
LHC won't be able to improve in this channel by much, golden decay channel B_s->ФФ
In SM:
After 10/fb: σ( ΔФ)=.05
ℑB−0.01
24.09.08 V.Gibson SUSSP57 St Andrews 10
FCNC decays b→d(s) only occur in loop diagrams in the Standard Model
• Exclusive Br’s expected ~O(10-5) or smaller in SM
B→K*γ , B →K*+-, B →µ +µ −
Excellent probe of new physics
• Within the Standard Model, rare decays are sensitive to the CKM matrix elements Vts and Vtd
Complementary measurements
Rare B Decays
b
sd ,
tcu ,,W-
γ,0Z
b
sd ,
tcu ,,
W
γ,0Z
b
sd ,
γ,0Z
New particle
loops
24.09.08 V.Gibson SUSSP57 St Andrews 11
B→µ µ
CMS expect 7 signal events with <1 background 5σ observation with 30fb-1
SM expectation• Br(Bs→µ µ ) = (3.5± 1.0)x10-9
• Br(Bd→µ µ ) = (1.0± 0.5)x10-10
Mass resolution Mass resolution
Full Full TrackerTracker
σ = 46 MeV
Bs→µ µ
Number events expected Bs→µ µ Bd →µ µ Bkgd
92 14 660 1 yr (1034cm-2s-1)
26 4.1 <6.4
24.09.08 V.Gibson SUSSP57 St Andrews 12
B→µ µ
Easy to trigger and reconstruct at LHC
Strong enhancement in CMSSM:
B K*µ µ
In SM this bs penguin decay contains right-handed calculable contribution but this could be added to by NP resultingin modified angular distributions
SM
B → K* μμ
?A very important property isforward-backward asymmetry..
..and position of its zero, which is robust in SM:
)(
2
09
70 sC
Cs
eff
eff
−=
AFB(s), fast MC, 2 fb–1
s = (mµ µ )2 [GeV2]
B K*µ µ : LHCb prospects
Forward-backward asymmetry AFB (s) in µ µ - rest frame is a sensitive NP probe Predicted zero of AFB (s) depends on Wilson coefficients C7
eff / C9eff
AFB(s), fast MC, 2 fb–1
s = (mµ µ )2 [GeV2]
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 C7
eff / C9eff
Full angular analysis gives better discrimination between models. Looks promising
Summary
In B-Physics one can probe New Physics via off-shell corrections
Promising hints for new physics from Tevatron and B-Factories
Most promising channel for 2009: βs