Tauonic, Radiative & Electroweak B Decays at Super-B Toru Iijima Nagoya University November 9, 2005 “Flavour in the era of the LHC” CERN Based on results and studies by Belle Letter of Intent for KEK Super B Factory ( KEK Report ) Physics at Super B Factory ( hep-ex/ ) cf) SLAC-R-709, “The Discovery Potential of a Super B Factory” Proceedings of the 2003 SLAC Workshops

2 CP violation Precise CKM Rare decays FCNC decays Tauonic decays  decays Lepton flavor violation Physics Targets at Super-B Using O(10 10 ) B and  (~100 x now) Search for new origin of flavor mixing and CPV. Figure by Dr.Hayasaka (Nagoya Univ.) This talk

3 Tauonic B Decays Charged Higgs contribution to B decays Leptonic: B   Semileptonic: B  D  c b  H/WH/W  H/WH/W  Br(SM) ~ 9 x Decay amplitude Tauonic decay is the most sensitive ! Br(SM) ~ 8 x 10 -3

4 B   (within the SM) Proceed via W annihilation in the SM. Branching fraction is given by Provide information of f B |V ub | –|V ub | from B  X u l f B cf) Lattice (  ~16%) –Br(B   )/  m d |V ub | / |V td | Expected branching fraction

5 Full Reconstruction Method Fully reconstruct one of the B’s to tag –B production –B flavor/charge –B momentum Υ(4S) e  (8GeV) e+(3.5GeV) B B  full (0.1~0.3%) reconstruction B  D  etc. Single B meson beam in offline ! Decays of interests B  Xu l, B  K  B  D ,  Powerful tools for B decays w/ neutrinos

6 Fully Reconstructed Sample Belle (253fb -1 ): 275M BB  2.5x10 5 B 0 B x10 5 B + B -

7 B   Status (Belle LP05/EPS05) N BB (produced) = 275M N B + B - (full recon.) = 4.0 x 10 5 (purity 0.55) Searched  decay modes –Cover 81% of the  decay Event selection –Residual ECL energy –Total net charge etc. Obtained E residual See K.Ikado’s talk at EPS05 and hep-ex/

8 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.    - mode has the best S/N ~1.

9 Prospect Will soon reach the SM. –3  evidence at ~700 fb -1 –5  discovery at ~2 ab -1 Expected precision at Super-B –13% at 5 ab -1 –7% at 50 ab -1 Search with D (*) l tag will help. (BaBar 232M BB, hep-ex/ ) –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 90%CL excluded region at present 95% CL excluded region at 5ab -1 (if B obs = B SM ) rHrH tan  /m H

11 B  D  (MC studies) Use fully reconstructed samples. T decay modes Analysis cuts; –Reject events w/ p, KL –Reject D (*)  contamination –No remaining charged or  0 tracks –ECL residual energy –Angle between two ’s –Missing mass Signal BG

12 Cont’d 5ab -1 50ab -1 ModeNsigNbkg  dB/BNsigNbkg  dB/B % % Expectation at 5 / 50 ab -1 for B + decay 5  observation possible at 1ab -1 Signal selection efficiency 10.2% 2.6% 26.1% 13.3% Major background source Missing charged and  tracks from B  D (*) l X (incl. slow  )

13 Constraint to Charged Higgs Once branching fraction is measured, we can constrain R. Form factor error M.Tanaka, Z.Phys. C67 (1995) 321 at 5ab -1  can be determined experimentally by B semiletonic decays

14 Cont’d  (Form-factor) ~15%  (Form-factor) ~5% Constraint From b  s  Present limit From B  

15 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 b  s  /sl + l - M(H + ) > 350 GeV already in TYPE II 2HDM Effective Hamiltonian for b  s |C 7 | by B  Xs , Sign of C 7, C 9, C 10 by B  Xsll

16 Measurement of B(B  X s l + l - ) Semi-inclusive technique –X s is reconstructed from K + or K s  (at most one  0 is allowed) –M Xs < 2.0 GeV Electron or muon pair –M ll >0.2GeV –Charmonium veto 140/fb data Theoretical prediction by Ali et al. Wrong flavor M Xs q2q2 M. Iwasaki et al. submitted to PRD, hep-ex/

17 C 7 = -C 7 SM Constraints on C i from B(B  X s l + l - ) Clean prediction for B(B  X s ll) with 1<q 2 <6GeV 2 is available. –Combine Belle and Babar results –Sign of C 7 flipped case with SM C 9 and C 10 value is unlikely. P.Gambino, U.Haisch and M.Misiak PRL (2005) BFBelleBabarWASMC 7 = -C 7 SM q 2 >(2m  ) ±1.15.6±2.04.5±1.04.4±0.78.8±0.7 1<q 2 <6GeV 2 1.5±0.61.8± ± ± ±0.25 C 10 NP C 9 NP Donut : 90% CL allowed region C 7 SM SM

18 B  K * ll FB Asymmetry Good electroweak probe for b  s loop. q 2 distribution has different pattern depending on sign(C 7 ). q 0 (the point w/ A FB =0) is sensitive for New Physics SM; q 0 2 =(4.2±0.6)GeV 2 B K*K* ll ll  B K*K* ll ll  Forward Backward

19 A 9 /A 7 A 10 /A 7 A FB : Belle Summer ‘05 357fb -1 (386M BB) N(K*ll)= (purity 44%) Unbinned M.L. fit to d  2 /dsd(cos  ) –8 event categories Signal + 3 cross-feed + 4 bkg. –Ali et al’s form factor –Fix |A 7 | to SM –Float A 9 /A 7 and A 10 /A 7 Results; w/ negative A 7 (SM like) w/positive A 7 ＳＭ A9/A7 A10/A7 Sign of A 9 A 10 is negative ! See Hep-ex/ & A.Ishikawa’s talk at EPS05

20 Prospect at 5ab -1  C 9 ~ 11%  C 10 ~14%  q 0 2 /q 0 2 ~11% 1000 pseudo experiments w/ SM input values Expected precision 5% at 50ab -1

21 Radiative Decays Inclusive Br(b  s  ) |C 7 |, SF for |V ub | B  K*  isospin asymmetry (  +-)sign of C 7 Mixing induced CPV Direct CPV in B  X s  B  X d  Summary by M.Nakao 1st Super-B workshop at Hawaii

22 B  X s  CP Asymmetry Sensitive to NP. Theoretically clean. Standard Model “~Zero”. –Gamma is polarized, and the final state is almost flavor specific. –Helicity flip of  suppressed by ~m s /m b Time dependent CPV requires vertex reconstruction with Ks   +  - C7C7 mbmb mbmb msms msms     Ks trajectory IP profile B vertex   Vertex recon. Eff. 51% (SVD2) 40% (SVD1) Possible at e + e - B-factory

23 B 0  K S  0  tCPV: Belle Summer ‘05 386MBB M(Ks  0 ) < 1.8GeV/c 2 –NP effect is independent of the resonance structure. Two M(Ks  0 ) regions(MR1: GeV/c 2 / MR2: <1.8GeV/c 2 ) (45+-11) events in MR1(2). Atwood, Gershon, Hazumi, Soni, PRD71, (2005) Result S= ±0.41 ±0.10 A= +0.12±0.27±0.10 Good tag (0.5<r<1.0) / 0.038A cp dir (B  Xs  ) / 0.10A cp mix (B  K*  K*  Ks  0 ) 50ab -1 5ab -1 Present Belle (stat./syst.)

24 A cp (B  X s  ) vs SUSY models mSUGURA tan  =30 U(2) tan  =30 SU(5)+ R tan  =30 degenerate SU(5)+ R tan  =30 non-degenerate mSUGURA tan  =30 U(2) tan  =30 SU(5)+ R tan  =30 degenerate SU(5)+ R tan  =30 non-degenerate Mixing CPV Direct CPV A cp dir A cp mix 5ab -1 50ab -1 T. Goto, Y.Okada, Y.Shimizu,T.Shindou, M.Tanaka hep-ph/ , 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  , D , A FB (K*ll), A CP (K  0  ) 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(D  ):7.9%  2.5% –q 0 2 of A FB (K*ll):11%  5% –A CP (K  0  ) tCPV:0.14  0.04

26 Backup Slides

27 CPV in b  s and SUSY Scenario Different SUSY breaking scenario can be distinguished in A cp mix (  Ks) - A cp mix (K* 0  ) correlation. Expected precision at 5ab -1 Correlation of other ovservables are also useful. A cp dir (X s  ), A FB (X s ll), Br(    ), CKM

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