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Physics in Collision, June 27-29, 2004, Youngjoon Kwon 1
Rare B decaysRare B decays
Introduction Hadronic two-body states
- non-factorizable processes Radiative & EW penguins Special subject: B DsJ X
Youngjoon KwonYonsei University
OverviewOverview
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 2
Physics Goals in B-Physics Goals in B-factoriesfactories
Establish CP violation in B decaysand over-constrain the SM picture of CP violation– any inconsistency?
Measure fundamental parameters of SM– 10 (out of 18, not counting neutrino masses, yet)
parameters are related with quark flavors– Belle, in particular, measures CKM triangle
parameters; angles & sides
Search for rare/forbidden decays and explore new physics effects
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 3
The major players in B The major players in B physicsphysics
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 4
Clean environment of Clean environment of B-factoriesB-factories
Energy difference:
Beam-constrained mass:
222 )()( iCMbc pEM
2CMi EEE
ee
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 5
B-factory with a clean B-factory with a clean initial stateinitial state
Kinematically clean environment of B production and decays
Provides an excellent laboratory to search for new particles & measure their properties– For example, B K X(3872), K c(2S)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 6
““Rare B decays”Rare B decays” b c W* is the dominant B decay process others are suppressed due to
– CKM suppression: b u
– Loop effect (“penguin”): b s, b d
bW+
gddt
s
bW+
u
du
V*ub
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 7
Motivation for Rare B Motivation for Rare B decaysdecays
SM is a very good approximation to reality.
i.e., for most processes
Need to consider processes where is small in order to be sensitive to new physics.– e.g. processes dominated by penguin loops
Compare Nature (exp.) with SM prediction for those sensitive processes
Find New Physics or learn new lessons
NPSMordinary AA
SMA
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 8
Where to look forWhere to look for – – two starting pointstwo starting points
CPV in Ks– Do we understand penguins?
• Radiative, EW• BF, ACP
as an ingredient for ()– Do we understand the strong-
interaction part?• QCDF, pQCD• Color-suppressed modes
0 0A A
00A
1
2A
1
2A
00A2
Let’s start with charmless 2-meson modes and see what we can learn!
22, 1 sin 2( )A S A 22, 1 sin 2( )A S A
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 9
Charmless 2-meson Charmless 2-meson final statesfinal states
Observables– BF– ACP
– polarization, etc.
Experimental concerns– continuum background – hadron ID: Cherenkov + dE/dx + TOF
on interpretation– isospin, SU(3)– Final state re-scattering
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 10
Discrimination of and Discrimination of and ContinuumContinuum
Combine into a Fisher (or NN)
Signalu,d,s,cbackground
Fisher Discriminant
Arb
itra
ry U
nit
sMonte Carlo
B produced (almost) at rest in Y(4S) frame
Isotropic B Jetty Continuum
BB
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 11
cleanest modes Both tree & penguin processes
can lead to direct CPV
may provide some info. on 2() & 3()but complicated, due to hadronic effects
KKKB , ,
d
bW
d
uus
0B
K
Vubd
b
W
tg
s
uu
d
0B
K
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 12
)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 13
610)2.06.07.1( BF610)3.06.01.2( BF
000 B
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 14
T/P ratio?T/P ratio?
K0+ +0
3* ~ udubVV
~*tstbVV
Mode CKM (fdecay)2 Ratio Exp Ratio BF (10-6)
K0+ 1 1 1 1 19.6
K*0+ 1 1.85 1.85 0.65 12.7
+0 2 0.66 0.03 0.27 5.3
+0 2 1.71 0.085 0.46 9.1
+0 2 2.9 0.145 1.35 26.4
bW+
gddt
s
bW+
u
du
V*ub
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 15
AACPCP in in
Belle result (152 million BB)-
KB0
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 16
Comparison w/ theory: Comparison w/ theory: BF & AcpBF & Acp
Mode BFExp
(10-6)
BF pQCD
(10-6)
ACP Expt
(%)
ACP pQCD
(%)
ACP QCDF
(%)
K+- 18.2 ± 0.8 13 – 19 -9 ± 3† -13 – -22 +5 ± 10
K0+ 19.6 ± 1.5 14 – 26 -1 ± 6 -0.6 – -1.5 0 ± 1
K+0 12.8 ± 1.1 8 – 14 0 ± 7 -10 – -17 +7 ± 10
K00 11.2 ± 1.4 8 – 14 3 ± 37 -3 ± 4
+- 4.55 ± 0.44 6 – 11 16 – 30 -6 ± 13
+0 5.3 ± 0.8 2.7 – 4.8 -7 ± 14 0 -2 ± 5
00 1.90 ± 0.47 0.33 – 0.65 45 ± 60
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 17
Longitudinal pol. in B Longitudinal pol. in B → → V VV V
fL = L /
100% Pol CP evenExpect: fL ~ 1 – O(M2
V/M2B)
B0 + -
NS = 93 ±22±9BaBar [> 5]
Cos(1) MES
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 18
B B (Belle) (Belle)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 19
B B → → and and K K** [[BaBar BaBar && BelleBelle]]
(Errors approximated) BF (10-6) ACP % Long. Poln %
B0→ ρ0 ρ0 < 2.1 (90 % CL)
B0→ ρ+ ρ- 27 ± 7 ± 6 99 ± 7 ± 3
B+→ ρ+ ρ0
Belle
22.5 ± 5.7 ± 5.8
31.7 ± 7.1 ± 6.7
-19 ± 23 ± 3
0 ± 22 ± 3
97 ± 7 ± 4
95 ± 11 ± 2
B+→ ρ0 K*+ 10.6 ± 3.0 ± 2.4 20 ± 32 ± 4 96 ± 15 ± 4
• CP asymmetries are consistent with zero
• Longituidnal polarization is ~1 as expected
CP even
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 20
Grossman-Quinn Grossman-Quinn bound :bound :
Grossman Quinn boundPRD 58 (1998) 017504
BF give model-independentlimits to the CP angle
)(
)(;
)(
)()(sin
0
000
0
0002
BBF
BBFor
BBF
BBFEff
)%90(55.045.055.4
45.09.1)(sin 2 CLEff
)%90(10.0827
1.2)(sin 2 CLEff
| - Eff| < 50o () and < 20o () at 90% CL
+ - is dominantly longitudinal polarised, CP-even final state
00000 , B
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 21
A concern on G-Q A concern on G-Q bound bound fromfrom
modifications from final-state interactions non-resonant background
000 B
Let’s consider a few decay modes potentially sensitive to FSI !
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 22
Not directly accessible through the spectator process Sensitive to W-exchange, or final state rescattering
potential for generating large theory uncertainty
in extracting CKM angle 3 from hadronic B decays Wide range of predictions: (0.3 ~ 6)x10-5
KDB s0
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 23
BF is consistent with p-QCD calculation, but in the upper edge of prediction
Similar FSI amplitudes – enhanced by (uu)/(ss) – should exist for color-suppressed modes such as D0 0, etc.
KDB s0
6.4 significance!
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 24
Color-suppressed B decaysColor-suppressed B decays
00*
00
D
D
0*
0
D
D
0*
0
D
D
00D
5.0 8.06.0 7.07.2
5.04.01.3
4.00.2
3.04.19.08.0
5.04.0
8.01.3
5.08.13.11.1
4.03.0
4.00.19.2
consistently larger thanthe factorization model
FSI re-scattering / W-exchange?
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 25
Color-suppressed B Color-suppressed B decaysdecays
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 26
Where to look forWhere to look for – – two starting pointstwo starting points
CPV in Ks– Do we understand penguins?
• Radiative & EW• BF, ACP
as an ingredient for ()– Do we understand the strong-interaction part?
• QCDF, pQCD• Color-suppressed modes
Now, let’s move on to look at the situationin the penguin sector!
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 27
B B K K(*)(*)
• Dominated by a single process (penguin) Expect similar BF for all modes
• Note: BF(B+) < 4x10-7 [90% CL] If large, it might indicate a large FSI • Longitudinal polarisation (expected) ~1
q
q
s
s
u u
B+,0
K(*)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 28
Belle
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 29
B B K K** angular angular distributionsdistributions
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 30
B B K K** angular angular distributionsdistributions
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 31
B B K K(*)(*) summary summary
Mode BF (10-6) ACP (%) Polarisation %
K0 7.6 ± 1.4 9.0 ± 2.2
K+ 10.0 ± 1.0 9.4 ± 1.3 4 ± 9 1 ± 13
K*0 11.2 ± 1.5 10.0 ± 1.8 4 ± 12 7 ± 16 65 ± 7 43 ± 10
K*+ 12.7 ± 2.4 6.7 ± 2.2 16 ± 17 -13 ± 31 46 ± 12
BaBar Belle
New physics, in penguin?(Y. Grossman hep-ph/0310229)
Or, something new to learnin phenomenology?
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 32
BF(BBF(B±±KK±±) at CDF) at CDF
• BR(B±K±) /BR(B±J/K±) = 0.0068 ±0.0021 (stat.) ± 0.0007 (syst.)
Using PDG 2002 for BR(B±J/K±):
• BR(B±K±) = (6.9 ± 2.1 (stat.) ± 0.8 (syst.)) x 10-6
powerful vertex trigger makes CDF a contender
Electroweak PenguinsElectroweak Penguins
*KB First penguin observationCLEO, PRL 1993
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 34
Branching Branching FractionsFractions
sXB
(x 10-6)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 35
EE spectrum in B spectrum in B X Xs s
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 36
EE in B in B X Xs s
CLEOCLEO
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 37
EE in B in B X Xs s (Belle) (Belle)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 38
EE in B in B X Xs s
(Belle)(Belle)
Signal selection is optimized formax. significance in 1.8 ~ 1.9 GeV
CLEO
Belle
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 40
CP asymmetry in B CP asymmetry in B X Xss CP asymmetry is expexted to be small (<1%) in SM some non-SM models allow large (~10%) ACP without changing the BF possible contamination from Xd (ACP can be large) but negligible in our measurement
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 41
CP asymmetry in B CP asymmetry in B X Xss
rawCPCP DAA
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 42
AACPCP(B (B X Xss Belle Belle
GeV) 1.2( 030.0050.0002.0)(
sX
CP
MsbA
096.0)(093.0 sbACP
9.252.393 N 9.250.392 N 6.98.520 N
tagged as 0, BB 0, BB ambiguous
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 43
AACPCP(B (B X Xss BaBar BaBar
015.0050.0025.0)( sbACP
11.0)(06.0 sbACP
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 44
AACPCP(B (B Xs Xs Summary Summary
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 45
Exclusive: B Exclusive: B K K**
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 46
B B K* K* asymmetries asymmetries
)()(
)()(
21
1**
**
KNKN
KNKN
wACP
012.0044.0015.0
CP asymmetry SM << 0.01
)()(
)()(*
00*0
*0
0*0
0
KBBKBB
KBBKBB
026.0044.0012.0
Isospin asymmetry SM << (5~10)%
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 47
Exclusive B Exclusive B X Xdd
3
22*
222
ts
td* /1
/1
)(
)( :SM
BK
B
Mm
Mm
V
V
KBB
BB
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 48
Exclusive B Exclusive B X Xdd
Standard Model predictions for BF’s
Prior measurements (in 10-6)
653.046.0
600
6
10)(1.58
10)18.0(0.49 ,10)34.0(0.90
B
BB
Ali & Parkhomenko (2001)
Bosch & Buchalla (2001)
1.0 4.4 9.2 1.2 2.6 17 2.1 2.7 13
00
BBB
CLEO Belle BaBar
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 49
Excl. B Excl. B X Xdd
unbinned 2D max. likelihood fit to E and Mbc
Fit region: |E| < 0.3 GeV
5.2 < Mbc < 5.3 GeV
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 50
B B X Xdd fitting fitting
)(
)(2)(2
0*0
0
*
0
0
00
0
KBBKB
BBBBB
017.0083.1with 0
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 51
B B X Xdd fitting fitting (projections)(projections)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 52
Exclusive: B Exclusive: B X Xdd
observed yield 280 749 197
signal yield 6.3 15.2 5.9signal
efficiency(%) 5.0 0.3 5.9 0.4 4.7 0.5
significance 3.5 incluing syst. err.Branching
Fraction 66.0
5.0 101.08.1
000 BBB
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 53
Semileptonic Semileptonic PenguinsPenguins
penguins (, Z) and W-box contribute sensitive to C9, C10 & sgn(C7)
( |C7| from bs) rich structure
– q2 distribution
– Forward-Backward asymmetry
lslb
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 54
InclusiveInclusive llXB s
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 55
llXBXB
eeXB
s
s
s
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 56
678.073.0
674.070.0
684.079.0
10]84.039.4[ )(10]06.131.4[ )(10]32.145.4[ )(
llXBBXBB
eeXBB
s
s
s
GeV 2.0)( llm
72 signal events6.2 significance
updated (preliminary)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 57
Main features Main features of of
Result is consistent with SM for both Xse+e & Xs+
– BF, m(l+ l), m(Xs)
– Kaon yield in m(Xs) & exclusive BKl+ l
Will remain interesting with even more statistics – BF is sensitive to Wilson coefficients C7, C9 & C10
– Detailed internal distributions m(l+ l), AFB are sensitive to new physics
llXB s
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 58
Exclusive Exclusive B B K K(*)(*) l l++ ll
first observed by Belle in 2001 (29/fb)first >3 evidence by BaBar (81/fb)first observed by Belle in 2003 (140/fb)
Main backgroundsB J/K(*), etc. veto! B K* conversion), B K*
m(ee) > 0.14 GeV
combinatorial from semileptonic, continuum
B K(*) fake
lKlB llKB *
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 59
B B K K(*)(*) l l++ ll updateupdate
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 60
B B K K(*)(*) l l++ ll--
is assumed to compensate for q2=0 pole for K*ee
factor 0.75 & SM values from Ali, et al. [caution] available SM predicted values vary by factor ~2
[Note]
73.3
9.2*
74.13.1
100.18.8 )(104.05.6 )(
llKBBlKlBB
76.2
4.2*
70.19.0
102.08.05.11 )(101.03.08.4 )(
llKBBlKlBB
7*
7
109.39.11 )( 102.15.3 )( :SM
llKBBlKlBB
DDsJsJ in B decays in B decays
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 62
Observations of Observations of DDsJsJ
BaBar (Apr. 2003 PRL)– Discovery of a new resonance at 2317 MeV
in CLEO (May 2003 PRD)
– another resonance at 2459 MeV in
0sD
0*sD
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 63
What’s so strange …?What’s so strange …? Surprisingly low mass compared to the
potential model expectations– below D(*) K threshold => narrow!
The masses are practically equal to those of similar states in the cu system:
Observed in the isospin-violating mode
Need to determine the quantum #’s and the BF’s
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 64
a potential model a potential model predictionprediction
Isgur & WisePRL 66, 1130 (1991)
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 65
on the other hand...on the other hand...
Prior to the DsJ observations,
there were theoretical papers that suggested:– Nowak, Rho, & Zahed, PRD 48, 4370 (1993)
– Bardeen & Hill, PRD 49, 409 (1994)
In the HQ limit,the j=1/2, 0+, 1+ states could be thought ofas the chiral partners of Ds and Ds*
the masses could be light
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 66
DDsJsJ(2457) : new decays ( (2457) : new decays ( ) )
• 1st observation
J 0
08.013.055.0
)2457(
)2457(0*
ssJ
ssJ
DDB
DDB
sD
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 67
DDsJsJ(2457) : new decays ( (2457) : new decays ( ) )
• 1st observation
JP 0+
02.004.014.0
)2457(
)2457(0*
ssJ
ssJ
DDB
DDB
sD
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 68
BD DsJ(2317)
DsJ(2317)Ds
BD DsJ(2457)
DsJ(2457)D*s
BD DsJ(2457)
DsJ(2457) Ds
DDsJsJ production in B production in B decaysdecays
B(B D DsJ(2317)) x B(DsJ(2317) Ds ) = (8.52.02.6)x 10-4
B(B D DsJ(2457)) x B(DsJ(2457) Ds*) = (17.84.25.3) x 10-4
B(B D DsJ(2457)) x B(DsJ(2457) Ds ) = (6.71.32.0) x 10-4
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 69
DDsJsJ(2457) (2457) DDss decay decay
0.55 0.13 0.08 (continuum) 0.38 0.11 0.04 (B decays)
Consistent with 1+ hypothesis, 0+, 2+ are excluded
in B DDsJ decays
0*)2457(
)2457(
ssJ
ssJ
DDBF
DDBF
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 70
spin-parity of spin-parity of DDsJsJ(2317)(2317)
B DDsJ is observed high J is not likely
All evidence favors JP = 0+ assignment
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 71
spin-parity of spin-parity of DDsJsJ(2457)(2457)
B DDsJ is observed high J is not likely
All evidence favors JP = 1+ assignment
Physics in Collision, June 27-29, 2004, Youngjoon Kwon 72
SummarySummary
Physics in the B-factories is getting really interesting!!
Rare B decays are excellent places to search for new physics and/or learn new things
ACP(B0K)=-0.090.03 B(B0)=(1.9 0.5)x10-6 fL(BK*)~0.5 « 1 color-suppressed decays
Great progresses in the EW penguin processes
Precise BF, ACP & E in B Xs B K(*)l+l- established; Xs l+l- improved
Discover/understand new states : DsJ spin-parity