16
SLAC DOE Review, Jun 7 20 06 1 CP Violation in Penguin Decays Denis Dujmic, SLAC
SLAC DOE Review, Jun 7 2006 1
CP Violation in Penguin Decays
Denis Dujmic, SLAC
SLAC DOE Review, Jun 7 2006 2
New Physics in Loop Decays? FCNC Amplitude in SM
0i
ii
iCKM
F0efff BμQfμCV
2GB H fA
3-6 QCD penguin7-10 EW penguin
Dominant terms double-CKM and QCD-loop suppressedDecay rates small in Standard Model: <7 10-5
Heavy non-SM particles can appear in loops- large contribution possible, ~O(1)- in general not CP-conserving
Study CPV in penguins:- probe for new CP-violating phases
Wb s
t,c,u
b sRb~
g~
Rs~g
23dRR)(δ
SLAC DOE Review, Jun 7 2006 3
Indirect CPV (beta)
b
dW
fA /J
0B SK
Tree decay, BF~10-3
i
Kcscb
cscb
BKsJ
e
qp
VVVV
pq
2
*
*
/
Both have same CP asymmetry parameter 2 Im[] = sin2Test this prediction!
b
d
0B
fA
SK
Penguin decay, BF~10-5
i
Ktstb
tstb
BKs
e
qp
VVVV
pq
2
*
*
(HFAG) 0.0320.685sin2β 0Kcc
SLAC DOE Review, Jun 7 2006 4
Standard Model or Beyond?
New Physics
This could be the greatest discovery of the century.Depending, of course, on how far down it goes.
All penguins 0.50 ± 0.06 (3difference!)
SLAC DOE Review, Jun 7 2006 5
SM Uncertainties
2)(* tftstb AVV 033.012sin
2)(* cfcscb AVV 2sin
b u
d
uWs
d
22sin iufusub eAVV 4)(*
CKM term Example diagram CPV Parameter
SM pollution!
t
c
u
b
b
b
s
s
s
SLAC DOE Review, Jun 7 2006 6
SM Uncertaintiescc
- Theory estimatesBeneke, PLB 620 (2005) 143Cheng, Chua & Soni, PRD72:094003(2005)-HFAG BaBar+Belle average-ccK average
Predictions based on factorization models
sin2QCDF, pQCD, SCET calculations agree
SLAC DOE Review, Jun 7 2006 7
Status of KKK0 CP Analysis
SLAC DOE Review, Jun 7 2006 8
Event Selection for B0→KKKS*2B
*2beamES pEm *
beam*B EEΔE
All K+K-KS KS
24.7 10-6
(530±28)4.2 10-6
(114±12)
Branching fraction (reco. events) K0 makes only 15% of the
total K+K-K0 branching fraction What goes into B0→K+K-K0
Dalitz plot?230 M BB pairs
SLAC DOE Review, Jun 7 2006 9
B0→KKK0: CP Content CP of final state not known!
- CP(K+K-) = even, CP(K+K-KS) = (-1)L
- need distribution of angular momenta L
Angular-moments analysis:
K+
K
B0
KSL
L’=L
H
L
HLL2 cosP PA
Piδ
S AeAA Compute wave strengths using moments of Legendre polynomials:
Describe decay in terms of S and P-waves decaying into K+K-
S-wave P-waveS-P interf.
SLAC DOE Review, Jun 7 2006 10
B0→KKK0: Angular Moments
6)%8(89f evenL
[BABAR,PhysRevD71:091102(2005)] BABAR’s – analysis of angular moments:
0
2evenL P
P451f
Average moments computed using sPlot technique [Pivk, Le Diberder, physics/0402083]
Outside of KS region BABAR 230 MBB
5)%9(93f evenL Belle 386 MBB (isospin)
Belle’s method requires 1.7 times more data to have same error
SLAC DOE Review, Jun 7 2006 11
Sin2 from KKK0Dalitz plot of K+K-KS consists of KS (CP-odd) + S-wave (CP-even):
-split sample into KS (CP-odd) and m(K+K-)>1.1 (CP-event)- treat any interference as syst. error
0Csin2βS eff
KKKS
In each mass region:
K0
Belle
BaBar “K+K-K0”BaBar
Belle
K0S
K0L
BABAR, ~230MBB
History plots of CP asymmetry measurements:
SLAC DOE Review, Jun 7 2006 12
What More? Dalitz plot!Time-dependent Dalitz plot rate:
Natural way to combine K0 and high-mass KKK0 decaysBest way to treat interference effects
tmAAqtmeAAmqAAe dtagdi
tag
t
cossin2222*22
Describe Dalitz plot amplitude in terms of (non)resonant components:
...NRccfccA...NRccfccA
NRc0c0f0
NRc0c0f0
0
0
SLAC DOE Review, Jun 7 2006 13
Understanding KKK0 Dalitz plot
D+,Ds+
reflections
X(1500)
non-res
[BABAR,hep-ex/0507094]
c0
Mode Fraction (%)(1020)KS 15.43.40.6X(1500)KS 5.22.20.9
(<8.3)38.97.30.9
Non-resonant
70.73.81.7
c0KS 3.11.60.8 (<5.5)
f0(980)KS 5.73.21.0 (<9.7)
-First B0->KKKS Dalitz plot analysis(time integrated)- Next: simultaneous fitting of entire Dalitz plot K0+KKK0 and extraction of CPV parameters
m(K+K-) [GeV/c2] m(K±KS) [GeV/c2]
SLAC DOE Review, Jun 7 2006 14
Other Progress in PenguinsImprovements of BABAR analyses (using 230 M BB pairs):
1) Add submodes of existing channels: - KS->- is only 34% of all K0 decays- Add KL: ’KL, KKKL- Add KS->: KSKSKS
2) Add channels with high background:- KS, KS
- Total penguin average for BABAR: (sin2) ~ 0.09
- Stat. power from additional modes alone: (sin2)stat ~ 0.16
SLAC DOE Review, Jun 7 2006 15
Performance for beta
BABAR ~230 MBBBelle ~386 MBB
Total error on sin2 as of Winter06
BABAR outperforms Belle even with less data- better analysis techniques- bigger boost, better PID
SLAC DOE Review, Jun 7 2006 16
Summary and Plans All channels will be updated with 2006 dataset
-BaBar error on sin2(’K0) < 0.1 -BaBar+Belle combined penguin error ~0.04
SLAC contribution:- KKKS KS→ (Dujmic), KS→ (Thompson,Roodman)- KS, f0KS -> KS (Graham) - KS, ->3 (Suzuki)- KS (Allen, Roodman):- K: (Allen, Roodman), - Dalitz plot: K+KSKS, K+K+K- (Thompson,Dujmic,Roodman)- conveners of physics working group (Dujmic,Graham)
beta
Direct CPV
