Tauonic, Radiative

1
Tauonic, Radiative Electroweak B Decays at
Super-B

• Toru Iijima
• Nagoya University

November 9, 2005 Flavour in the era of the LHC
workshop _at_ CERN
Based on results and studies by Belle
Letter of Intent for KEK Super B Factory ( KEK
Report 2004-4 ) Physics at Super B Factory (
hep-ex/0406071 )
cf) SLAC-R-709, The Discovery Potential of a
Super B Factory Proceedings of the 2003 SLAC
Workshops
2
Physics Targets at Super-B
Search for new origin of flavor mixing and CPV.

• CP violation
• Precise CKM
• Rare decays
• FCNC decays
• Tauonic decays
• t decays
• Lepton flavor violation

Figure by Dr.Hayasaka (Nagoya Univ.)
This talk
Using O(1010) B and t (100 x now)
3
Tauonic B Decays

• Charged Higgs contribution to B decays
• Leptonic B?t n
• Semileptonic B?D t n

Br(SM) 9 x 10-5
Br(SM) 8 x 10-3
Decay amplitude
Tauonic decay is the most sensitive !
4
B?t n (within the SM)

• Proceed via W annihilation in the SM.
• Branching fraction is given by
• Provide information of fBVub
• Vub from B?Xu l n fB cf) Lattice (d16)
• Br(B?tn)/Dmd Vub / Vtd
• Expected branching fraction

5
Full Reconstruction Method

• Fully reconstruct one of the Bs to tag
• B production
• B flavor/charge
• B momentum

Decays of interests B?Xu l n, B?K n n
B?Dtn, tn
B
e- (8GeV)
e(3.5GeV)
?(4S)
p
full (0.10.3) reconstruction B?Dp etc.
B
Single B meson beam in offline !
Powerful tools for B decays w/ neutrinos
6
Fully Reconstructed Sample

• Belle (253fb-1) 275M BB ? 2.5x105 B0B0 4.2x105
  BB-

7
B?t n Status (Belle LP05/EPS05)

• NBB (produced) 275M
• NBB- (full recon.)
• 4.0 x 105 (purity 0.55)
• Searched t decay modes
• Cover 81 of the t decay
• Event selection
• Residual ECL energy
• Total net charge
• etc.

Obtained Eresidual
See K.Ikados talk at EPS05 and hep-ex/0507034
8
Contd

• Overall
• Signal efficiency 33.7
• Expected signal 13.5 (SM)
• Background est. 31.4
• N observed 39

Upper limit calculated by M.L. fit.
t?p- n mode has the best S/N 1.
9
Prospect

• Will soon reach the SM.
• 3s evidence at 700 fb-1
• 5s discovery at 2 ab-1
• Expected precision
• at Super-B
• 13 at 5 ab-1
• 7 at 50 ab-1
• Search with D() l n tag will help.
• (BaBar 232M BB, hep-ex/0507069)
• Tag eff 1.75 x 10-3
• Signal selection eff. 31
• Similar S/N to Belle

10
Impact to Charged Higgs

• effects to branching fraction

90CL excluded region at present
95 CL excluded region at 5ab-1 (if Bobs BSM)
11
B?D t n (MC studies)

• Use fully reconstructed samples.
• T decay modes
• Analysis cuts
• Reject events w/ p, KL
• Reject D() t n contamination
• No remaining charged or p0 tracks
• ECL residual energy
• Angle between two ns
• Missing mass

Signal
BG
12
Contd

• Signal selection efficiency

10.2 2.6
26.1 13.3

• Expectation at 5 / 50 ab-1 for B decay

5ab-1 5ab-1 5ab-1 5ab-1 50ab-1 50ab-1 50ab-1 50ab-1
Mode Nsig Nbkg S dB/B Nsig Nbkg S dB/B
280 550 12.7 7.9 2800 5500 40.3 2.5
620 3600 12.7 7.9 6200 36000 40.3 2.5
5s observation possible at 1ab-1

• Major background source
• Missing charged and g tracks from B?D() l n X
  (incl. slow p)

13
Constraint to Charged Higgs

• Once branching fraction is measured, we can
  constrain R.

M.Tanaka, Z.Phys. C67 (1995) 321
r can be determined experimentally by B
semiletonic decays
at 5ab-1
14
Contd
Constraint From b?sg
D(Form-factor) 5
D(Form-factor) 15
Present limit From B?t n
15
b?sg/sll-

• Possible to search for NP in theoretically clean
  way.
• Many observables
• Branching fractions
• Mixing indcued CPV
• Direct CPV
• Forward-backward asym.
• Ratio of exclusive modes

Effective Hamiltonian for b?s
C7 by B?Xsg, Sign of C7, C9, C10 by B?Xsll
M(H) gt 350 GeV already in TYPE II 2HDM
16
Measurement of B(B?Xsll-)
M. Iwasaki et al. submitted to PRD, hep-ex/0503044

• Semi-inclusive technique
• Xs is reconstructed from K or Ks 0-4p (at most
  one p0 is allowed)
• MXs lt 2.0 GeV
• Electron or muon pair
• Mllgt0.2GeV
• Charmonium veto

140/fb data
Wrong flavor
MXs
q2
Theoretical prediction by Ali et al.
17
Constraints on Ci from B(B?Xsll-)
P.Gambino, U.Haisch and M.Misiak PRL 94 061803
(2005)

• Clean prediction for B(B?Xsll) with 1ltq2lt6GeV2 is
  available.
• Combine Belle and Babar results
• Sign of C7 flipped case with SM C9 and C10 value
  is unlikely.

BF Belle Babar WA SM C7 -C7SM
q2gt(2mm)2 4.111.1 5.62.0 4.51.0 4.40.7 8.80.7
1ltq2lt6GeV2 1.50.6 1.80.9 1.600.5 1.570.16 3.300.25
C10NP
C10NP
Donut 90 CL allowed region
SM
C9NP
18
B?Kll FB Asymmetry

• Good electroweak probe for b?s loop.
• q2 distribution has different pattern depending
  on sign(C7).

Forward
Backward
q0(the point w/ AFB0) is sensitive for New
Physics SM q02(4.20.6)GeV2
19
AFB Belle Summer 05

• 357fb-1 (386M BB)
• N(Kll)114-14 (purity 44)
• Unbinned M.L. fit to dG2/dsd(cosq)
• 8 event categories
• Signal 3 cross-feed 4 bkg.
• Ali et als form factor
• Fix A7 to SM
• Float A9/A7 and A10/A7
• Results
• w/negative A7 (SM like)
• w/positive A7

Sign of A9A10 is negative !
See Hep-ex/0508009 A.Ishikawas talk at EPS05
20
Prospect at Super-B
1000 pseudo experiments w/ SM input values
Expected precision
_at_ 5ab-1 dC9 11 dC10 14 d q02/q02 11
5 at 50ab-1
21
Radiative Decays

• Inclusive Br(b?sg) C7, SF for Vub
• B?Kg isospin asymmetry (D-) sign of C7
• Mixing induced CPV
• Direct CPV in B?Xsg
• B?Xd g

Summary by M.Nakao 1st Super-B workshop at Hawaii
22
B?Xsg CP Asymmetry

• Sensitive to NP.
• Theoretically clean.
• Standard Model Zero.
• Gamma is polarized, and the final state is almost
  flavor specific.
• Helicity flip of g suppressed by ms/mb
• Time dependent CPV requires vertex reconstruction
  with Ks ?pp-

Vertex recon. Eff. 51 (SVD2) 40 (SVD1)
Possible at ee- B-factory
23
B0?KSp0g tCPV Belle Summer 05

• 386MBB
• M(Ksp0) lt 1.8GeV/c2
• NP effect is independent of the resonance
  structure.
• Two M(Ksp0) regions(MR10.8-1.0GeV/c2 / MR2
  lt1.8GeV/c2)
• 70-11 (45-11) events in MR1(2).

Atwood, Gershon, Hazumi, Soni, PRD71, 076003
(2005)
Result
S 0.08 0.41 0.10 A 0.120.270.10
Good tag (0.5ltrlt1.0)
50ab-1
5ab-1
Present Belle (stat./syst.)
0.04
0.14
0.41 / 0.10
Acpmix(B?Kg, K?Ksp0)
0.005
0.011
0.051 / 0.038
Acpdir(B?Xsg)
24
Acp(B?Xsg) vs SUSY models
5ab-1
50ab-1
Mixing CPV
Direct CPV
mSUGURA tanb30
U(2) tanb30
U(2) tanb30
mSUGURA tanb30
Acpdir
Acpmix
SU(5)nR tanb30 non-degenerate
SU(5)nR tanb30 degenerate
SU(5)nR tanb30 non-degenerate
SU(5)nR tanb30 degenerate
T. Goto, Y.Okada, Y.Shimizu,T.Shindou,
M.Tanaka hep-ph/0306093, also in SuperKEKB LoI
25
Summary

• Tauonic, Radiative and Electroweak B decays are
  of great importance to probe new physics.
• We are starting to measure B?tn, Dtn, AFB(Kll),
  ACP(Kp0g) etc. at the current B factories.
• Hot topics in the coming years !
• For precise measurements, we need Super-B !
• Expected precision (5ab-1?50ab-1)
• Br(tv) 13?7
• Br(Dtn) 7.9?2.5
• q02 of AFB(Kll) 11?5
• ACP(Kp0g) tCPV 0.14?0.04

26
Backup Slides
27
CPV in b?s and SUSY Scenario

• Different SUSY breaking scenario can be
  distinguished in Acpmix(fKs) - Acpmix(K0g)
  correlation.

Expected precision at 5ab-1
Correlation of other ovservables are also
useful. Acpdir(Xsg), AFB(Xsll), Br(t?mg), CKM
28
(No Transcript)
29
(No Transcript)