Intensa atividade experimental
BTEV
2001
?
1999
A
T
L
A
S
2008
CLEO 3
Além de dezenas de grupos experimentais
pelo mundo …
1999
BELLE
Oscilações matéria – antimatéria
mésons neutros B0 oscilam
Bd (bd )  Bd (b d )
d
t
b
Interações comuns ΔB=1 de troca
de q (2/3)
virtual t : dominant amplitude
ΔB=2
b
d
d
w-
w-
Bs (bs )  Bs (b s)
decaimento
t
b
ewc
d
e
Vtd
Δmd
fB constante de decaimento
BB Bag fator de “sacola”
Matriz de CKM
VCKM
=
 v ud

 v cd
v
 td
v us
v cs
v ts
v ub 

v cb 
v tb 
 1  / 2

 Vub e

2
2
1  / 2
A
 
  V e i V ei
1
ts
 td
2
=
Os autoestados eletrofracos dos quarks
são conectados aos estados de massa pela
matriz de CKM:
Bd  Bd
fase de mistura
Bs  Bs
fase de mistura
 i





Fase do
decaimento fraco
quatro parâmetros
A, λ, ρ, η
Triângulos de unitariedade

Vtd Vtb +Vcd


Vcb +Vud Vub = 0



(,)
Vtd Vud +Vts Vus +Vtb Vub =

0
Vub

(0,0)
Vtd
Vcb
No MP:
     
Vub

(1,0)
Vtd

Vts


No MP:
• medir todos os ângulos
• medir todos os lados
MP: consistência!
     0.03
2
violação de CP
Três manifestações possíveis de violação de CP:
Violação de CP direta
(interferência entre duas amplitudes de decaimento)
Violação de CP indireta
(interferência entre duas amplitudes de mistura)
Violação de CP na interferência entre decaimentos que
oscilam (misturam) e entre decaimentos que não
oscilam.
formalismo dependente do tempo para Bd
amplitude de decaimento para
Af  f H B 0
Bd  f
evolução temporal
Af  f H B 0
0
f H Bphys
(t )  e imt e
B
0
 t
2
A cos
f
1
2
mt  i qp Af sin 12 mt
fCP
B
0
CP violation: interference between mixing and decay
p Af

q Af

formalismo dependente do tempo para Bd
B f (t )  Bf (t )
A (t ) 
B f (t )  Bf (t )
CP
f
A (t )  A cosmt  A
CP
f
dir
 1
mix
2
A
MP:
dir

 1
=0
=0
2
A
mix

Fábricas de b: Δt
LHCb: t
sin mt
2 Im 
 1
2
=+sin(2β)
=-sin(2β)
B0→J/ψKS
B0→J/ψKL
Medindo β
Decaimentos do tipo B0→J/ψKS e B0→J/ψKL
0
B
b
d
W
c
c
s
d
J/
b
K
0
c
g
0
B
t,c,u
c
s
W
J/
K0
d
d
Bem entendidos na teoria: árvore and pinguin tem mesma fase
Experimento “relativamente simples”
CP  1
Bd   KS ,c KS , c1KS
CP  1
Bd  J  KL
  CP e
2i
medindo β
(D. Lange)
Fábricas de B : Belle, BaBar
colisores e  e  assimétricos em ( 4S )
 bb
33
-2 -1
L

3
10
cm
s
 1 nb
Um ano: ~ 100 M pares
 Ldt
Belle 132 fb-1
Março, 2003
Produção
BB
BaBar 117 fb-1
BB coerente
KEKB
Luminosidade alcançada:
1.06 x1034 cm-2s-1
Detetor Babar
Sumário de sin2b em b  ccs
Média mundial
0.734  0.055
Já uma medida
precisa: 7.5%
rarer B decays
b  cc d
Cabbibo supressed
c
g
B0 → J/ 0
b
B
b  sq q
B → f KS
t,c,u
0
0
B

b
W
d
d
s
g

b
g
u, d
J/
0
W
d
W
B
c
d
s
s
f
s
u, d
B → ‘ KS
Sensitive to new physics:
• smaller amplitudes, NP through interf. terms
• virtual particles (SUSY?) in penguin loops
not theoretically clean
smaller rates, higher back.
b
B
K
t,c,u
s
s
W
u, d
c
c
J/
d
d
0
f
K
u, d
,f
Same CKM structure as B0→J/ψKS
expect S=sin2β to 5%
B0 → J/ 0
S = - sin2β if no penguin
C = 0 if no penguin
Measuring β in b→sss
Theoretical especulations
• sin(2β) = SϕK=-0.39 +- 0.41 (2.7 σ) from
the SM prediction;
• models from SUSY could explain this
result!
G.L. Kane et al., PRL Apr.2003
Grossman et al. hep-ph/0303171
SM is alive and well!
Confidence levels in the large (rhobar,etabar) plane
obtained from the global fit. The constraint from the WA
sin2beta (from psi Ks modes) is included in the fit.
Confidence levels in the large (rhobar,etabar) plane
obtained from the global fit. The constraint from the WA
sin2beta (from psi Ks modes) is overlaid.
2007
• More data  (sin2 )  o(102 ) close to theory limit from
penguin pollution;
• Measurement of ΔmS improve |Vtd/Vcb| from near
cancellation of Bd and Bs form factor;
• More data from B→hulν and B→hcX together with
improvement in theory will give some improvement in
|Vtd/Vcb| ;
Strategy: new physics!
Goal: Physics beyond the
Standard model
• Measurements which provide a
reference case for SM effects;
• Compare this to channels that
might be affected by New Physics;
• Understand experimental and
theoretical systematics to a level
where we can draw conclusions.
statistics!!
BdJ/KS
Bd
BsJ/f
Bs DsK
Hadronic b production
B hadrons at Tevatron
• b quark pair produced

preferentially at low 
• highly correlated
tagging
low pt cuts
   ln(tan( / 2))

for larger  the B
boost  increses rapidly
LHCb Experiment
• Dedicated B physics Experiment at the
LHC
– pp collisions at 14TeV
Muon System
Z ~ 15.0-20.0 m
• Acceptance :
– 15-300mrad
(bending)
RICH2
– 15-250mrad Z ~ 9.5-11.9 m
(non-bending)
• Particle ID
– RICH
detectors
– Calorimeters
– Muon
Detectors
Calorimeters
RICH1
Z ~ 1.0-2.2 m
Z ~ 12.5-15.0 m
One event!
Tracking performance
Average efficiency = 92 %
Efficiency for p>5GeV >95%
Ghost rate pT>0.5 GeV ~ 7%.
Mass resolution
(~13 MeV)
for the decay channel
Bs  Ds +
Ds KKπ
Momentum resolution:
p/p=0.38%
<N> = 27 tracks/event
Proper time
resolution (42 fs)
Hadron ID : Physics Performance
n
n
n
RICH essential for
hadronic decays
Example : Bs  K+K-
Sensitive to CKM angle 
No RICH
n
n
Signal Purity improved from
13% to 84% with RICH
Signal Efficiency 79%
With RICH
Muon Identification
Muons selected by searching for muon stations hits
compatible with reconstructed track extrapolations
– Compare track slopes and distance of muon station hits
from track extrapolation
For P>3GeV/c
eff = 96.7  0.2 %
misid = 2.50  0.04 %
Measuring β B  J KS
o
d
 “gold-plated” decay channel at B-factories for measuring the Bd- Bd mixing phase
 needed for extracting γ from Bd ππ and Bs  K K
 in SM Adir=0, non-vanishing value (~0.01) could be a signal of Physics Beyond SM
 precision measurement important
ACP(t)
 A  0.022
 A  0.023
mix
dir
Inputs:
220 k/year signal
194 k/year back.
Amix=sin(2β)=0.73
Adir = 0
ps
Rare B decays
In the SM:
Excellent probe of indirect
effects of new physics!
• flavour changing neutral currents
only at loop level
• very small BR ~ 105 or smaller
BS     
, l+l-
9
SM : BR ~10
• observation of the decay
• measurement of its BR
LHCb : 2 fb-1
~ 33 signal events
~ 10 events background
σM = 38 MeV
CMS : 100 fb-1 (107s at 1034 cm-2s-1)
~ 26 signal events
6.4 events background
Rare B decays
Bd  K    
AFB (s)
s  ( p    p _ )
Forward-backward asymmetry
can be calculated in SM and other models
BTeV data compared to
Burdman et al calculation
A. Ali et al., Phys. Rev. D61
074024 (2000)
Conclusions
CP violation is a cool research topic!!
B factories established CP violation in the B sector and are making interesting
measurements;
LHCb and BTeV are second generation beauty CP
violation experiments;
They are well prepared to make crucial measurements
in flavour physics with huge amount of statistics;
Impressive number of different strategies for measurements of
SM parameters and search of New Physics;
Exciting times: understanding the origin of
CP violation in the SM and beyond.