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Tauonic, Radiative & Electroweak B Decays at Super-B. November 9, 2005 “Flavour in the era of the LHC” workshop @ CERN. Toru Iijima Nagoya University. Based on results and studies by Belle. Letter of Intent for KEK Super B Factory ( KEK Report 2004-4 )

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Tauonic radiative electroweak b decays at super b

Tauonic, Radiative & Electroweak B Decays at Super-B

November 9, 2005

“Flavour in the era of the LHC” workshop @ CERN

Toru Iijima

Nagoya University

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


Physics targets at super b
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)


Tauonic b decays

H+/W+

t+

c

b

H+/W+

t+

nt

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 !


B t n within the sm
Bt n (within the SM)

  • Proceed via W annihilation in the SM.

  • Branching fraction is given by

  • Provide information of fB|Vub|

    • |Vub| from BXu l n fB cf) Lattice (d~16%)

    • Br(Btn)/Dmd |Vub| / |Vtd|

  • Expected branching fraction


Full reconstruction method
Full Reconstruction Method

  • Fully reconstruct one of the B’s 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)

Υ(4S)

p

full (0.1~0.3%)

reconstruction

BDp etc.

B

Single B meson beam in offline !

Powerful tools for B decays w/ neutrinos


Fully reconstructed sample
Fully Reconstructed Sample

  • Belle (253fb-1): 275M BB  2.5x105 B0B0 + 4.2x105 B+B-


B t n status belle lp05 eps05
Bt n Status (Belle LP05/EPS05)

  • NBB (produced) = 275M

  • NB+B- (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.Ikado’s talk at EPS05

and hep-ex/0507034


Cont d
Cont’d

  • 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-nmode has the best S/N ~1.


Prospect
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


Impact to charged higgs

rH

tanb/mH

Impact to Charged Higgs

  • effects to branching fraction

90%CL excluded region

at present

95% CL excluded region

at 5ab-1 (if Bobs = BSM)


B d t n mc studies
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 n’s

    • Missing mass

Signal

BG


Cont d1
Cont’d

  • Signal selection efficiency

10.2%

2.6%

26.1%

13.3%

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

5s observation possible at 1ab-1

  • Major background source

  • Missing charged and g tracks from BD(*) l n X (incl. slow p)


Constraint to charged higgs

Form factor error

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


Cont d2
Cont’d

Constraint

From bsg

D(Form-factor) ~5%

D(Form-factor) ~15%

Present limit

From Bt n


B s g sl l
bsg/sl+l-

  • 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+) > 350 GeV already

in TYPE II 2HDM


Measurement of b b x s l l
Measurement of B(BXsl+l-)

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 < 2.0 GeV

  • Electron or muon pair

    • Mll>0.2GeV

    • Charmonium veto

140/fb data

Wrong flavor

MXs

q2

Theoretical prediction by Ali et al.


Constraints on c i from b b x s l l

C7 = -C7SM

C7SM

Constraints on Ci from B(BXsl+l-)

P.Gambino, U.Haisch and M.Misiak PRL 94 061803 (2005)

  • Clean prediction for B(BXsll) with 1<q2<6GeV2is available.

    • Combine Belle and Babar results

    • Sign of C7 flipped case with SM C9 and C10 value is unlikely.

C10NP

C10NP

Donut : 90% CL

allowed region

SM

C9NP


B k ll fb asymmetry

l-

l+

B

B

q

q

K*

K*

l-

l+

BK*ll FB Asymmetry

  • Good electroweak probe for bs loop.

  • q2 distribution has different pattern depending on sign(C7).

Forward

Backward

q0(the point w/ AFB=0) is sensitive for New Physics

SM; q02=(4.2±0.6)GeV2


A fb belle summer 05

A10/A7

A9/A7

A10/A7

SM

A9/A7

AFB: Belle Summer ‘05

  • 357fb-1 (386M BB)

  • N(K*ll)=114+-14 (purity 44%)

  • Unbinned M.L. fit to dG2/dsd(cosq)

    • 8 event categories

      • Signal + 3 cross-feed + 4 bkg.

    • Ali et al’s 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.Ishikawa’s talk at EPS05


Prospect at super b
Prospect at Super-B

1000 pseudo experiments w/ SM input values

Expected precision

@ 5ab-1

dC9 ~ 11%

dC10 ~14%

d q02/q02 ~11%

5% at 50ab-1


Radiative decays
Radiative Decays

  • Inclusive Br(bsg) |C7|, SF for |Vub|

  • BK*g isospin asymmetry (D+-) sign of C7

  • Mixing induced CPV

  • Direct CPV in BXsg

  • BXdg

Summary by M.Nakao

1st Super-B workshop

at Hawaii


B x s g cp asymmetry

mb

C7

ms

ms

mb

p+ p-

Ks trajectory

B vertex

IP profile

g

g

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 p+p-

Vertex recon. Eff.

51% (SVD2)

40% (SVD1)

Possible at e+e- B-factory


B 0 k s p 0 g tcpv belle summer 05
B0KSp0g tCPV: Belle Summer ‘05

  • 386MBB

  • M(Ksp0) < 1.8GeV/c2

    • NP effect is independent of the resonance structure.

  • Two M(Ksp0) regions(MR1:0.8-1.0GeV/c2 / MR2: <1.8GeV/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= +0.12±0.27±0.10

Good tag (0.5<r<1.0)

Present Belle (stat./syst.)

5ab-1

50ab-1

Acpmix(BK*g, K*Ksp0)

0.41 / 0.10

0.14

0.04

Acpdir(BXsg)

0.051 / 0.038

0.011

0.005


A cp b x s g vs susy models
Acp(BXsg) vs SUSY models

5ab-1

50ab-1

Mixing CPV

Direct CPV

U(2)

tanb=30

mSUGURA

tanb=30

U(2)

tanb=30

mSUGURA

tanb=30

Acpdir

Acpmix

SU(5)+nR

tanb=30

non-degenerate

SU(5)+nR

tanb=30

degenerate

SU(5)+nR

tanb=30

non-degenerate

SU(5)+nR

tanb=30

degenerate

T. Goto, Y.Okada, Y.Shimizu,T.Shindou, M.Tanaka

hep-ph/0306093, also in SuperKEKB LoI


Summary
Summary

  • Tauonic, Radiative and Electroweak B decays are of great importance to probe new physics.

  • We are starting to measure Btn, Dtn, AFB(K*ll), 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(K*ll): 11%5%

    • ACP(Kp0g) tCPV: 0.140.04



Cpv in b s and susy scenario
CPV in bs and SUSY Scenario

  • Different SUSY breaking scenario can be distinguished in Acpmix(fKs) - Acpmix(K*0g) correlation.

Expected precision at 5ab-1

Correlation of other ovservables are also useful.

Acpdir(Xsg), AFB(Xsll), Br(tmg), CKM


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