MSSM Charged Higgs from Top Quark Decays

Marcela Carena Marcela Carena FermilabFermilab

Top Quark SymposiumTop Quark SymposiumMichigan Center for Theoretical PhysicsMichigan Center for Theoretical Physics

University of Michigan, Ann Arbor, April 2005University of Michigan, Ann Arbor, April 2005

based on works done in collaboration with:based on works done in collaboration with:Garcia, Nierste and Wagner, Garcia, Nierste and Wagner, Nucl. Phys. B 577 Nucl. Phys. B 577

(2000)(2000)Boos, Buchinev and Wagner, Boos, Buchinev and Wagner, in preparationin preparation

Outline Introduction: MSSM Higgs SectorIntroduction: MSSM Higgs Sector

Radiative Corrections to decay rateRadiative Corrections to decay rate

resummation of LO and NLO logs of Standard QCD resummation of LO and NLO logs of Standard QCD

corrections via OPEcorrections via OPE resummation of dominant SUSY corrections for largeresummation of dominant SUSY corrections for large to all orders in perturbation theoryto all orders in perturbation theory

The impact of tau polarization in charged Higgs The impact of tau polarization in charged Higgs searchessearches

fit to pion energy distributions from polarized tau fit to pion energy distributions from polarized tau decays & charged Higgs mass measurements at ILCdecays & charged Higgs mass measurements at ILC

bHt

tan

Standard Model Standard Model effective theory effective theory Supersymmetry Supersymmetry interesting alternative BSM interesting alternative BSM

If SUSY exists, many of its most important motivationsIf SUSY exists, many of its most important motivations demand some SUSY particles at the TeV range or belowdemand some SUSY particles at the TeV range or below

1. solve the hierarchy problem 2. generate EWSB by quantum corrections 3. Allow for gauge coupling unification at a scale 4. induce a large top quark mass from Yukawa coupling evolution.5. provide a good dark matter candidate: the lightest neutralino6. provide a possible solution to baryogenesis

Minimal model: 2 Higgs SU(2) doublets 5 physical states: 2 CP-even h, H with mixing angle 1 CP-odd A and a charged pair

Higgs Physics: important tool in understanding SupersymmetryHiggs Physics: important tool in understanding Supersymmetry

GeV1016

H

LLR P tanv

2 ; P tanP cot

v

2 mgmmg

HbtbtH

limit

decoupling

M m If ZA

After quantum corrections, Higgs mass shifted due to incompletecancellation of particles and superparticles in the loops

• Main effects: top and stop loops; bottom and sbottom loops for large tanb

M.C., Quiros, Wagner; M.C.,Haber

Radiative corrections to Higgs MassesRadiative corrections to Higgs Masses

• Main Quantum effects:

enhancement ; dependence

on stop mixing and logarithmic

sensitivity to

4tm

tX

SM

Upper bound : Upper bound :

stringent test of the MSSMstringent test of the MSSMGeV135hm

MSSM Higgs Masses as a function of MSSM Higgs Masses as a function of MMAA

LEP MSSM HIGGS limits:

• Mild variation of the charged Higgs mass with SUSY spectrum

)m (smaller 00AA sizeable and sizeable If H54bt

254

2A

2

Hv)(m m

Radiative Corrections to Higgs Couplings

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

Important modifications of couplings due to radiative Important modifications of couplings due to radiative corrections: depending on MSSM parameter spacecorrections: depending on MSSM parameter space

• strong suppression/enhancement of the charged Higgs coupling to top-bottomdepending on sign of sign of mu for positive gluino mass

• Similar behaviour for the CP-odd Higgs b-b coupling

Renormalization Group EffectsRenormalization 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 logs done

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

Hbt RL

)/(log bnn

s mQ

)/(log1b

nns mQ S

SM

tan)(1

1

v

)()(hb

SUSYb

bbb MQm

mQmmQ

)1()Q/mlog(mor mQ bHt Os

Braaten,Leveille; Drees, Hikasa

Czarnecki, Davidson

M.C., Garcia, Nierste, Wagner

Quantum Corrections to bHt• leading and subleading log(Q/mb) resummed using mb running in & • One-loop finite QCD terms also included

0

After higher order tanb enhanced SUSY corrections included:

30 ,10tan GeV 125mH

loop1

loop1

imp. QCD

imp. QCD

imp. MSSM

imp. MSSM

imp. QCD

loop-1 MSSM

loop-1 MSSM

Charged Higgs Searches at theTevatronCharged Higgs Searches at theTevatron(a RunI example soon to be improved: Eusebi et al. (CDF) in prep.)Eusebi et al. (CDF) in prep.)

Curves of constant after resummation of LOand NLO logs fo QCD

bHtBR

Shaded area excluded by DO RunI analysisSimilar for CDF.

Including SUSY corrections for large tanb anda heavy SUSY spectrum

GeV 500 GeV 500

Drastic variations on bounds in the planedepending on MSSM parameter space

Hmtan

M.C., Garcia, Nierste, Wagner

Tau Polarization & Charged Higgs Measurements

In the rangeIn the rangeit seems difficult to identify decays from

Crucial Observation:

Due to the lefthandness of the charged current: Due to the lefthandness of the charged current:

whereaswhereas

a consequence of the helicity-flipa consequence of the helicity-flip

(conserving) of the SM Higgs(conserving) of the SM Higgs

(vector boson) couplings(vector boson) couplings

Hence: Hence:

This holds in general in models withThis holds in general in models with

only only

1)/BR(H vmm tH

WH

)(W W LRRL ..cheWL LL

)(H H LLRR

1 1 WH PP

and RL P

PPP :conventionBy

LR

LR

The decay distributions of the are sufficiently different The decay distributions of the are sufficiently different from those of from those of

Considering the main contributions to one-prong hadronic Considering the main contributions to one-prong hadronic

tau decays:tau decays:

The dependence of the tau polarization of the angularThe dependence of the tau polarization of the angular

distributions of the primary decay modes in the tau rest framedistributions of the primary decay modes in the tau rest frame

all three channels all three channels

have an importanthave an important

dependence on dependence on

For this study I willFor this study I will

only use only use

R

L

(7.5%) (24%)

%);5.12( 00

10

a

cos P121

dcos

d1

cos P12

2/

dcos

d12v

2

2vL

vL

mm

m

cos P12dcos

d12v

2

2vvT

vT

mm

mP

In the colinear limit In the colinear limit

Energy distributions arising fromEnergy distributions arising from

are significantly are significantly

different from different from

decaysdecays

Most energetic particles from Most energetic particles from

decays decays transv. polarized transv. polarized Most energetic particles fromMost energetic particles from

decays decays & long. polarized & long. polarized

1/ mE

E

Ez ; )]12( P1[BR

d

d1

zz

-L h W

-R hH

-L-R

1,a

1,a

Energetic pions favour charged Higgs over W’s

Bullock, Hagiwara, Martin

Charged Higgs searches at the ILCCharged Higgs searches at the ILC::the impact of tau Polarizationthe 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

bH bWtt- ee

jets2W

H

W

-1fb 500 and GeV 500s

In the top rest frame:

where the resonance R is either the W boson or the charged Higgs

where:

bbbR t

1P and 1P : Recall HW M. Nojiri: Boos, Martyn,Moortgat-Pick, Sachwitz, Sherstnev and Zerwas for stau pair production: (R equiv. stau)

--meson energy spectrum in the top rest frame

Two MSSMTwo MSSM benchmarkbenchmark

MSSM scenarios:MSSM scenarios:

common parameters:

(a)

(b)

TeV 1MMMMM 2g~DUQ

GeV 500A t

% 24 b)H(t BR

Gev 500 )b

% 10 b)H(t BR

Gev 500 )a

GeV 130m 50 tanH

Performing a fit to the simulated Performing a fit to the simulated signal + backgroundsignal + background

(b)(a)

one can determine the value of

In particular we obtain:

(no systematics/detector effects)

2top

2

Hmin m2m Hx

GeV )9.04.129(m a)H

GeV )5.07.129(m b)H

Conclusions Low energy supersymmetry has an important impact on Higgs physicsLow energy supersymmetry has an important impact on Higgs physics. . It leads to definite predictions to the Higgs boson couplings to fermions It leads to definite predictions to the Higgs boson couplings to fermions

and gauge bosonsand gauge bosons. .

Such couplings, however, are affected by radiative corrections induced by Such couplings, however, are affected by radiative corrections induced by supersymmetric particle loops. supersymmetric particle loops. It affects Higgs searches at hadron and It affects Higgs searches at hadron and lepton colliders in an important way.lepton colliders in an important way.

QCD and SUSY quantum corrections to lead to crucialQCD and SUSY quantum corrections to lead to crucial effects in the interpretation of searches from top decays at the Tevatroneffects in the interpretation of searches from top decays at the Tevatron

Tau Lepton polarization is a powerful discriminative characteristic to Tau Lepton polarization is a powerful discriminative characteristic to separate charged Higgs signal separate charged Higgs signal

two representative scenarios with tHtwo representative scenarios with tH++b suppressed/enhanced couplings b suppressed/enhanced couplings shown for ILC.shown for ILC.

Fit to pion spectra from polarized tau decays allows to extract light chargedFit to pion spectra from polarized tau decays allows to extract light charged Higgs masses withHiggs masses with (theoretical study, but only info (theoretical study, but only info on from used!)on from used!)

GeV 15.0δmH

P

bHtH

CPCPsupersuperHH

Code to compute Higgs spectrum, couplings and decay modes in the Code to compute Higgs spectrum, couplings and decay modes in the presence of CP-violationpresence of CP-violation

Lee, Pilaftsis, M.C., Choi, Drees,Ellis, Lee,Wagner.’03Lee, Pilaftsis, M.C., Choi, Drees,Ellis, Lee,Wagner.’03

CP-conserving case: Set phases to zero. Similar to HDECAY, but with CP-conserving case: Set phases to zero. Similar to HDECAY, but with the advantage that charged and neutral sector treated with same rate the advantage that charged and neutral sector treated with same rate of accuracy.of accuracy.

Combines calculation of masses and mixings by Combines calculation of masses and mixings by M.C., Ellis, Pilaftsis,M.C., Ellis, Pilaftsis,

Wagner.Wagner. with analysis of decayswith analysis of decays byby Choi, Drees, Hagiwara, Lee and Song. Choi, Drees, Hagiwara, Lee and Song.

Available at Available at

http://theory.ph.man.ac.uk/~jslee/CPsuperH.htmlhttp://theory.ph.man.ac.uk/~jslee/CPsuperH.html