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B  tn and B  D ( * ) tn decays at BaBar

B  tn and B  D ( * ) tn decays at BaBar. Guglielmo De Nardo University of Napoli “Federico II” and INFN Representing the BaBar collaboration 36 th International Conference on High Energy Physics July 2012, Melbourne, Australia. Tagging method. Tag this B. Then look for signal.

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B  tn and B  D ( * ) tn decays at BaBar

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  1. B  tn and B  D(*)tndecays at BaBar Guglielmo De Nardo University of Napoli “Federico II” and INFN Representing the BaBar collaboration 36th International Conference on High Energy Physics July 2012, Melbourne, Australia

  2. Tagging method Tag this B Then look for signal e+,μ+ νμ,νe ντ ντ ϒ(4S) τ+ B+ ντ X- B- e+,μ+ νμ,νe ϒ(4S) τ+ B+ ντ D0 • Weak signal signature • Decay with missing momentum (many neutrinos in the final state) • Lack of kinematics constraints in final state • background rejection improved reconstructing the companion B • Look for signal in the rest of the event • Expect to find nothing more than visible signal decay products • No additional track and little activity in the calorimeter

  3. Leptonic B decays l+ b + W+ B+ u nℓ l+ b H+ B+ u nℓ • Interesting probe of physics beyond the SM, since also a charged Higgs can mediate the decay • B ➝ tn used in global UT fits. B ➝ mn out of reach of current B-factories B ➝ lnvery clean theoretically. SM uncertainty in the B decay constant fB .and |Vub| value.

  4. B  tnwith hadronic tags at BaBar arXiv:1207.0698[hep-ex] Submitted to Phys.Rev.D (R) MC modelling ofsignal EextraPDF checked with double tags tm te tr tp Fit to residual energy in calorimenter simultaneously in 4 reconstructed modes (tenn, tmnn, tpn, trn) Floating parameters: BF and 4 background yields Combinatorial B tag background estimated from data.B+ background shape from MC Excess of events over background of 3.8 s

  5. Comparison with the 2HDM type II B tn measurement SM BABAR BaBar|Vub| measurement (exclusivedecays) BaBar|Vub| measurement (inclusive decays) Uncertainty in Standard Model predictionmostly due to |Vub||Vub|incl = (4.33 ± 0.28)×10-3|Vub|excl= (3.13 ± 0.30)×10-3fB = (189 ± 4) MeV (HPQCD arXiv:1202.4914)

  6. Constraints on the tan b vs mH+plane in 2HDM type II Excl. at 2s Excl. at 3s Excl. at 2s Excl. at 3s Exclusive |Vub| Inclusive|Vub| Most of the parameterspace of 2HDM isexcludedat 90% C.L., ifwe assume exclusive |Vub| determination 90% C.L. exclusion for mH+up to 1 TeVatvery high tan b (>70) usinginclusive|Vub|

  7. Ratio of B  D(*)tn to B  D(*) tn D* only H+ contr. here Semileptonicdecays with a t We test the SM measuring the ratios SM predictions are R(D) = 0.297 ± 0.017 and R(D*) = 0.252 ± 0.003

  8. Analysis strategy arXiv:1205.5442[hep-ex] Submitted to Phys.Rev.Lett. PDF taken from Monte Carlo • Full reconstruction of a tag B in hadronicdecays. • Identify e or m and reconstruct a D meson (D*+, D*0, D+, D0) • Kinematicrequirement: q2 > 4 GeV2 • 2D likelihoodfit to M2miss=(Pee-ptag-pD-pl)2 and p*l YieldsfloatingFixedparameters B  D l nnormalization BB combinatorial and continuum bkgs B  D tnsignal cross-feedsamongmodes B  D** l n background (from a D(*)p0 l n CS) p*l M2miss

  9. B  D* t nresults

  10. B  D t nresults

  11. SystematicUncertainties D(*) p0 l n Control sample M2miss • Mainsystematicsuncertainties • D** background yield from aD(*)p0 l n Data control sample • SignalMC statistic • For PDF extraction • BB and continuum background

  12. Comparison with Standard Model Z. Phys C46, 93 (1990) PRD 82, 0340276 (2010) PRD 85, 094025 (2012) and recentupdates Combininationyields c2 / n.d.o.f. = 14.6/2 (probability: 6.9 × 10-4) 3.4saway from SM

  13. 2HDM type II cannotexplain the excess PRD 78, 015006 (2008) PRD 85, 094025 (2012) Takinginto account the effect of tan b/mH on efficiency R(D)  tan b/mH= 0.44 ± 0.02 R(D*)  tan b/mH = 0.75 ± 0.04 Mutuallyexclusive with CL >99.8% A ChargedHiggswithin 2HDM type II contribution:

  14. Conclusions • Updatedresult on B  t n with hadronictagging BF(B t n ) = (1.8 ± 0.5± 0.2) × 10-4.arXiv:1207.0698 [hep-ex], submitted to Phys.Rev.D (R) Agreement with the SM in tensionusingexclusive |Vub| measurements (2.4s)Betteragreementusing inclusive |Vub| (1.6s) • Improvedmeasurement of R(D(*)) = BF(B D(*)t n) / BF(B  D(*) l n) R(D*) = 0.332 ± 0.024 ± 0.018 R(D) = 0.440 ± 0.058 ± 0.042exceeding the SM predictedvalues by 3.4 s. arXiv:1205.5442[hep-ex], submitted to Phys.Rev.Lett. • 2HDM type II (alone) cannot accomodate the results and theoristsalreadyat work building models

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