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Charged Higgs Search with B  D t + n t

Charged Higgs Search with B  D t + n t. Physics Motivation. Branching ratio: , is sensitive to the charged Higgs mass ( M H ). Probe for minimal SUSY SM. Br ( B  D tn t ) = ??? %. Br ( B  D l n m ) = (2.14 ± 0.20) % (PDG2003).

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Charged Higgs Search with B  D t + n t

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  1. Charged Higgs Searchwith B Dt+nt Super B Factory Workshop

  2. Physics Motivation Branching ratio: , is sensitive to the charged Higgs mass (MH ). Probe for minimal SUSY SM. Br (BDtnt)= ??? % Br (BDlnm)= (2.14±0.20) % (PDG2003) The sensitivity depends on vacuum expectation of two Higgs fields: tan b = vu/vd.

  3. Decay of B Dt+nt BDt+nt= ~0.8% (SM) u/d u/d B D b c H+/W+ t+ nt Heavier lepton has better sensitivity to H±

  4. Analysis Overview signalB D B t + t +h+nt, l+nlnt nt (4S) tagB B full reconstruction • Decay of signalB includes 2 or more neutrinos. • TagB should be fully reconstructed to identify signal B. • SignalB is searched for in the remained particlesusing kinematic selection.

  5. MC Sample • Fast simulated MC-sample with fully-reconstructed B • Charged B: 3.0 ab-1 (3.2×106 events) • Neutral B: 6.1 ab-1 (3.2×106 events) • Signal B: Generic decay • Tag B: Already ‘fully-reconstructed’ • We ‘fully-reconstruct’ tag B seeing generator information. • Reconstruction efficiency of tag B in this sample = 100%. • Statistics can be increased while saving processing time.

  6. B Decays We Search for (1) C.C. implicitly included signalB D0K+p- 4% K+p-p0 13% K+p-p-p- 7% K+p-p-p-p0 4% KSp0 1% KSp+p- 2% KSp+p-p0 4% Total 35% D0 B+ t+ nt Searched for in generic B decays. (4S) Tag B decay products are tagged using generatorinformation. tagB t+p+nt 11% r+nt 25% l+ntnl 35% Total 71% B-

  7. B Decays We Search for (2) signalB C.C. implicitly included D- B0 t+ D-K+p-p- 9% K+p-p-p0 6% KSp+ 1% Total 16% nt Searched for in generic B decays. (4S) t+p+nt 11% r+nt 25% l+ntnl 35% Total 71% Tag B decay products are tagged using generatorinformation. tagB B0

  8. B Dt +nt : Event Selection (1) • Particle selection • Kaon: PID(K) > 0.4. • Pion: PID(p) > 0.6. • Photon: ECL cluster energy, Eg > 50 MeV. • r- reconstruction • . • D0 reconstruction • .

  9. B Dt +nt : Event Selection (2) • Event rejection by signal-B decay products • Events with proton or KL in signal-B decay are rejected. • B- D*0t-nt event rejection • If D*0 is reconstructed,reject the event. • Constraints on remained particles • Neither charged particle nor p0 is allowed after signal B and tag B reconstruction. • Residual ECL energy sum < 100 MeV.

  10. B Dt +nt : Event Selection (3) • Dt+(h+nt)nt modes • Angle between two neutrinos: -1.0 < cos q < 0.8. • Missing mass squared: | pB- pD- ph |2 > 0.1 (GeV/c2)2 | pB- pD- ph |2 (GeV/c2)2 cos q

  11. B Dt +nt : Event Selection (4) • Dt+(l+nlnt)nt modes • Missing mass squared: | pB- pD- pl|2 > 1.2 (GeV/c2)2

  12. Reconstruction Efficiencies Full-recon. efficiency is not included.

  13. Statistical Significance Assuming BDt+nt= ~0.8% BDt+ntis measurable in 12s significance at 5 ab-1.

  14. Dominating Background Modes • For modes • For modes • For modes 45% 58% 20%

  15. Constraint on Charged Higgs Mass R = MWtanb / MHas a function of integrated luminosity systematic error not included r is a parameter, which dominates an uncertainty of the hadron form factor. The r can be experimentally determined by semi-leptonic B decays. may be given with 5 ab-1 data.

  16. Summary • B  Dt+nt is one of sensitive decays to the charged Higgs. Because other-side-B should be fully-reconstructed, this mode calls for the statistical power of the SuperB factory. • The reconstruction efficiency and S/N of this mode are studied using large number of fast simulated MC samples. • At the integrated luminosity of 5 ab-1, Br(charged B  Dt+nt) can be measured in the statistical significance of 12s. • At the limit of no systematic uncertainty of Br(charged B  Dt+nt) measurement, MH > MWtanb / 11 may be constrained with 5 ab-1 data.

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