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MSSM Charged Higgs from Top Quark Decays

This presentation discusses the MSSM Higgs sector, radiative corrections to decay rate resummation, and the impact of tau polarization in charged Higgs searches. It also covers the measurements of charged Higgs mass at the ILC and the implications for Supersymmetry.

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MSSM Charged Higgs from Top Quark Decays

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  1. MSSM Charged Higgs from Top Quark Decays Marcela Carena Fermilab Top Quark Symposium Michigan Center for Theoretical Physics University of Michigan, Ann Arbor, April 2005 based on works done in collaboration with: Garcia, Nierste and Wagner, Nucl. Phys. B 577 (2000) Boos, Buchinev and Wagner, in preparation

  2. Outline • Introduction: MSSM Higgs Sector • Radiative Corrections to decay rate resummation of LO and NLO logs of Standard QCD corrections via OPE resummation of dominant SUSY corrections for large to all orders in perturbation theory • The impact of tau polarization in charged Higgs searches fit to pion energy distributions from polarized tau decays & charged Higgs mass measurements at ILC

  3. Standard Model  effective theory Supersymmetry  interesting alternative BSM If SUSY exists, many of its most important motivations demand some SUSY particles at the TeV range or below • solve the hierarchy problem • generate EWSB by quantum corrections • Allow for gauge coupling unification at a scale • induce a large top quark mass from Yukawa coupling evolution. • provide a good dark matter candidate: the lightest neutralino • provide a possible solution to baryogenesis Minimal model: 2 Higgs SU(2) doublets5 physical states: 2 CP-even h, H with mixing angle 1 CP-odd A and a charged pair Higgs Physics: important tool in understanding Supersymmetry

  4. Upper bound : stringent test of the MSSM Radiative corrections to Higgs Masses After quantum corrections, Higgs mass shifted due to incomplete cancellation of particles and superparticles in the loops • Main effects: top and stop loops; bottom and sbottom loops for large tanb • Main Quantum effects: • enhancement ; dependence • on stop mixing and logarithmic • sensitivity to M.C., Quiros, Wagner; M.C.,Haber

  5. MSSM Higgs Masses as a function of MA • Mild variation of the charged Higgs mass with SUSY spectrum LEP MSSM HIGGS limits:

  6. Radiative Corrections to Higgs Couplings

  7. For the charged Higgs one has important radiative corrections for large tanb

  8. Important modifications of couplings due to radiative corrections: depending on MSSM parameter space • strong suppression/enhancement of the charged Higgs coupling to top-bottom • depending on sign of  sign of mu for positive gluino mass • Similar behaviour for the CP-odd Higgs b-b coupling

  9. Renormalization Group Effects • tanb enhanced correc. to hb are not the only universal ones • Standard QCD corrections to transitions involving Yukawa interactions log(Q/mb) with: -- Summation to all orders in leading logsdone evaluating running hb(Q) mb(Q) -- Full one-loop QCD correc. to decay rates require summation of NLO logs due to non-log terms To consider both effects: using OPE + RG evolution in The above relation is also valid at the scale Q  the characteristic scale of the process Braaten,Leveille; Drees, Hikasa Czarnecki, Davidson M.C., Garcia, Nierste, Wagner

  10. Quantum Corrections to • leading and subleading log(Q/mb) resummed using mb running in & • One-loop finite QCD terms also included  After higher order tanb enhanced SUSY corrections included:

  11. Charged Higgs Searches at theTevatron(a RunI example soon to be improved:Eusebi et al. (CDF) in prep.) Curves of constant after resummation of LOand NLO logs fo QCD Shaded area excluded by DO RunI analysis Similar for CDF. Including SUSY corrections for large tanb and a heavy SUSY spectrum Drastic variations on bounds in the plane depending on MSSM parameter space M.C., Garcia, Nierste, Wagner

  12. Tau Polarization & Charged Higgs Measurements • In the range it seems difficult to identify decays from Crucial Observation: Due to the lefthandness of the charged current: whereas  a consequence of the helicity-flip (conserving) of the SM Higgs (vector boson) couplings Hence: This holds in general in models with only

  13. The decay distributions of the are sufficiently different from those of Considering the main contributions to one-prong hadronic tau decays: The dependence of the tau polarization of the angular distributions of the primary decay modes in the tau rest frame all three channels have an important dependence on For this study I will only use

  14. Bullock, Hagiwara, Martin In the colinear limit Energy distributions arising from are significantly different from decays • Most energetic particles from decays  transv. polarized • Most energetic particles from decays  & long. polarized Energetic pions favour charged Higgs over W’s

  15. Charged Higgs searches at the ILC:the impact of tau Polarization • We consider  with and Main background: both tops decay into Wb and • Simulations done with CompHEP, including ISR and beamstrahlung with polarized • Polarized decays with TAUOLA, using new CompHEP-TAUOLA interfase (E. Boos et al.) • All other stages done with CompHEP-Pythia interface • Energy distributions are given in the reconstracted top rest frame using the recoil mass technique

  16. In the top rest frame: where the resonance R is either the W boson or the charged Higgs where: M. Nojiri: Boos, Martyn,Moortgat-Pick, Sachwitz, Sherstnev and Zerwas for stau pair production: (R equiv. stau)

  17. -meson energy spectrum in the top rest frame (a) Two MSSMbenchmark MSSM scenarios: common parameters: (b)

  18. Performing a fit to the simulated signal + background (b) (a) one can determine the value of In particular we obtain: (no systematics/detector effects)

  19. Conclusions • Low energy supersymmetry has an important impact on Higgs physics.  It leads to definite predictions to the Higgs boson couplings to fermions and gauge bosons. • Such couplings, however, are affected by radiative corrections induced by supersymmetric particle loops. It affects Higgs searches at hadron and lepton colliders in an important way.  QCD and SUSY quantum corrections to lead to crucial effects in the interpretation of searches from top decays at the Tevatron • Tau Lepton polarization is a powerful discriminative characteristic to separate charged Higgs signal two representative scenarios with tH+b suppressed/enhanced couplings shown for ILC. • Fit to pion spectra from polarized tau decays allows to extract light charged Higgs masses with (theoretical study, but only info on from used!)

  20. CPsuperH • Code to compute Higgs spectrum, couplings and decay modes in the presence of CP-violation Lee, Pilaftsis, M.C., Choi, Drees,Ellis, Lee,Wagner.’03 • CP-conserving case: Set phases to zero. Similar to HDECAY, but with the advantage that charged and neutral sector treated with same rate of accuracy. • Combines calculation of masses and mixings by M.C., Ellis, Pilaftsis, Wagner.with analysis of decaysbyChoi, Drees, Hagiwara, Lee and Song. • Available at http://theory.ph.man.ac.uk/~jslee/CPsuperH.html

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