developments on cross-section and br of higgs production: part 2 bsm

Developments on cross-section and BR of Higgs production: part 2 BSM

Mónica L. Vázquez Acosta - Imperial CollegeMónica L. Vázquez Acosta - Imperial College

(on behalf of the LHC Higgs Cross Section WG)(on behalf of the LHC Higgs Cross Section WG)

Higgs Hunting Workshop, 30/07/2011Higgs Hunting Workshop, 30/07/2011

Thanks to M. Flechl, R. Harlander, M. Krämer, M. Spira, M. Schumacher, R. Tanaka & M. Warsinsky for the useful discussions and help preparing this talk

Developments on cross-section and BR of BSM Higgs production: M. Vázquez Acosta (Imperial) Higgs Hunting Workshop, 30/07, 2011 - 2

Standard Model and SupersymmetryStandard Model and SupersymmetryStandard Model and SupersymmetryStandard Model and SupersymmetryThe Standard Model does amazing job describing physics at the weak scale ~100 GeV, butHierarchy problem in Higgs sectorIf Higgs boson is fundamental particlei) there are no high-mass particles which couple to the Higgs field (even indirectly)ii) Striking cancellation are needed in high-order loop corrections to MHIGGS

SUSY at the TeV scale provides an elegant solution to hierarchy problem- Introduces super-partners of SM particles and cancels problematic loop corrections - Allows light Higgs in context of GUT without fine tuning


Minimal Super-Symmetric ModelMinimal Super-Symmetric ModelMinimal Super-Symmetric ModelMinimal Super-Symmetric ModelIn minimal supersymmetric extension of SM there are 2 scalar doublets Φ1 couples to down-type fermions, Φ2 to up-type fermions → Higgs sector described by 4 masses and 2 mixing angles

3 of 8 degrees of freedom absorbed by Z, W after EW symmetry breaking:

5 physical Higgs bosons

β (VEVs): tan β = v2/v1 [v12+v2

2 = v2 = 2MZ2 /(g2

2+g12) = (246 GeV)2]

•MSSM Higgs sector @ tree level determined by: MA & tan

Mass hierarchies: Mh < MZ, MA < MH & MW < MH

MH,h2 = ½[ (MA

2 +MZ2 ) ± ((MA

2 +MZ2)2 – 4MZ

2MA2 (cos22))1/2 ]

MH+2 = MA

2 + MW2

Mh < MZ

•Radiative corrections increase upper bound on Mhmax

~ 130 GeV

•Upper bound reached at large MA → SM-like h

• h, H (scalar, CP-even)• A (pseudo-scalar, CP-odd)• H (charged)


MSSM Neutral Higgs CouplingsMSSM Neutral Higgs CouplingsMSSM Neutral Higgs CouplingsMSSM Neutral Higgs Couplings

is a mixing angle between neutral components for two Higgs doublets H10, H2

0 to give the physical CP-even Higgs bosons h, H: cos2 = -cos2 [(MA

2-MZ2)/(MH

2-Mh2)]

For large MA → cos « • h couplings SM-like• H coupling to W,Z suppressed

For large tan coupling enhancedfor down-type fermions. Important for b-quarks and since Higgs coupling proportional to mass

SM

Djouadi, Kalinowski, Spira

tan = 5 tan = 30


CP-Conserving Benchmark ScenariosCP-Conserving Benchmark ScenariosCP-Conserving Benchmark ScenariosCP-Conserving Benchmark ScenariosProposed by Carena et al., Eur.Phys.J.C26,601(2003)

Unconstrained MSSM has large number of free parameters. Choose specific parameter points: benchmark scenarios

cos

sinSMHbbhbb gg

FeynHiggs curves

• Mhmax scenario

maximal Mh< 133 G eVConservative exclusion bounds on tan β and MA

Used at LEP/Tevatron, MSUSY= 1 TeV

• No-mixing scenarioSmall Mh<116GeVNo stop mixing, Xt=0, MSUSY=2TeV

• Gluophobic scenariosmall gh,gluon

main production channel ggh strongly suppressedMh<119 GeV, MSUSY=350GeV

• Small-α scenariosmall ghbb and gh

Mh<123 GeV, MSUSY=800GeV


Neutral Higgs Production MechanismsNeutral Higgs Production MechanismsNeutral Higgs Production MechanismsNeutral Higgs Production Mechanisms

gg fusion: dominant at small & moderate tan in comparison with associated production. Mediated by top/bottom loops (also stop/sbottom loops for M < 400 GeV)

Associated production: tt only important for h bb dominant process for large tan

VBF: important when h at upper mass limit “SM-like” and H at lower mass bound. (No VBF for A at tree level)

Not important for MSSM neutral Higgs production


gggg→→((=h,H,A) Neutral Higgs =h,H,A) Neutral Higgs ProductionProduction

gggg→→((=h,H,A) Neutral Higgs =h,H,A) Neutral Higgs ProductionProduction

Dominant MSSM Higgs production for small and moderate value of tan

- quark loops @ NLO QCD: full quark mass dependence D. Graudenz, M. Spira, and P. Zerwas, Phys. Rev. Lett. 70 (1993) 137 M. Spira, A. Djouadi, D. Graudenz, and P. M. Zerwas, Phys. B 453 (1995) 17 M. Spira, A. Djouadi, D. Graudenz, and P. Zerwas, Phys. Lett. B318 (1993) 347 R. Harlander and P. Kant, JHEP 0512 (2005) 015•The QCD corrections increase cross section by 100% for small tan and up to 50% in large tan region, where bottom loop is dominant due to enhanced Yukawa couplings

- quark loops @ NNLO QCD: heavy quark limit R. V. Harlander and W. B. Kilgore, Phys. Rev. Lett. 88 (2002) 201801 V. Ravindran, J. Smith, and W. L. van Neerven, Nucl. Phys. B665 (2003) 325 M. Spira, A. Djouadi, D. Graudenz, and P. Zerwas, Phys. Lett. B318 (1993) 347 R. Harlander and P. Kant, JHEP 0512 (2005) 015 C. Anastasiou, S. Beerli, S. Bucherer, A. Daleo, and Z. Kunszt, JHEP 0701 (2007) 082 U. Aglietti, R. Bonciani, G. Degrassi, and A. Vicini, JHEP 01 (2007) 021, arXiv:hep-ph/0611266. R. Bonciani, G. Degrassi, and A. Vicini, JHEP 11 (2007) 095•Can only be used for small and moderate values of tan

- NNLL resummation: not available for the pseudo-scalar Higgs


gggg→→((=h,H,A) Neutral Higgs Production=h,H,A) Neutral Higgs Productiongggg→→((=h,H,A) Neutral Higgs Production=h,H,A) Neutral Higgs Production• Grids of scalar and pseudo-scalar Higgs cross sections for bottom & top loops• s-top and s-bottom loops neglected so far

tb, bb: NLO QCD (HIGLU - M. Spira, hep-ph/9510347) tt: NLO QCD (HIGLU) & NNLO heavy quark limit (GGH@NNLO – R. Harlander, W. Kilgore Phys.Rev.Lett. 88 (2002) 201801 & JHEP 0210 (2002) 017

)

gtMSSM/gt

SM, gbMSSM/gb

SM: Feynhiggs 2.7.4S. Heinemeyer, W. Hollik, G. Weiglein Comput.Phys.Commun.124 (2000) 76 Eur.Phys.J.C9 (1999) 343 & Eur.Phys.J. C28 (2003) 133 M. Frank, T. Hahn, S. Heinemeyer, W. Hollik, H. Rzehak, G. Weiglein JHEP 0702 (2007) 47

PDF: MSTW2008 (NLO & NNLO)S(MZ)=0.12018 (NLO), 0.11707 (NNLO) R = F = M (varied by a factor 2)

PDF+S uncertainty: 15 %

Scale uncertainty: 10-15 %

LHC Higgs Cross Section Group arXiv:1101.0593 [hep-ph]

mhmax scenario


Feynhiggs: Yukawa Couplings & MassesFeynhiggs: Yukawa Couplings & MassesFeynhiggs: Yukawa Couplings & MassesFeynhiggs: Yukawa Couplings & Masses

decoupling limit

P. Kant, R.V. Harlander, L. Mihaila, M. Steinhauser, JHEP 1008 (2010) 104Light MSSM Higgs boson mass to three-loop accuracy (not used yet)

tan

tan

bottom coupling

top coupling

bottom coupling

Light scalar Higgs: h

top coupling

Pseudoscalar Higgs: Amhmax scenario


Neutral Higgs: ggNeutral Higgs: gg→A Cross Section→A Cross SectionNeutral Higgs: ggNeutral Higgs: gg→A Cross Section→A Cross Section

tan=5 tan=10

tan=30

mhmax scenario

tan=50

Large tanb-loop dominant

Low-medium tanvirtual top thresholdfor MA = 2 mt

arXiv:1101.0593[hep-ph]

mt=172.5 GeV


Neutral Higgs: ggNeutral Higgs: gg→h Cross Section→h Cross SectionNeutral Higgs: ggNeutral Higgs: gg→h Cross Section→h Cross Section

mhmax scenario

tan=5 tan=10

tan=30 tan=50

MA >> MZ

Decoupling limitNNLO SM

Most of the regionis dominated bylow MA values



Neutral Higgs: ggNeutral Higgs: gg→H Cross Section→H Cross SectionNeutral Higgs: ggNeutral Higgs: gg→H Cross Section→H Cross Section

mhmax scenario

Large tanb-loop dominant

Low-medium tanvirtual top thresholdfor MA = 2mt

tan=5 tan=10

tan=30 tan=50


mt=172.5 GeV


gggg→H: →H: SUSY NLO QCD CorrectionsSUSY NLO QCD Correctionsgggg→H: →H: SUSY NLO QCD CorrectionsSUSY NLO QCD Corrections

- SUSY QCD corrections: full mass dependence (not used yet) C. Anastasiou, S. Beerli, and A. Daleo, Phys. Rev. Lett. 100 (2008) 241806 M. Muhlleitner, H. Rzehak, and M. Spira, ArXiv: 1001.3214 [hep-ph]•for mh

max scenario: less than 10 %

ArXiv: 1001.3214 [hep-ph]

Small scenarioPhys. Rev. Lett. 100 (2008) 241806

tan=30


gggg→→ Cross Section Cross Section with SUSY QCD correctionswith SUSY QCD corrections

gggg→→ Cross Section Cross Section with SUSY QCD correctionswith SUSY QCD corrections

mhmax scenariogluophobic scenario tan=10

LHC

Tevatron

NLO QCD + SUSY ( s-quark & s-gluino) QCD corrections

HIGLU contains SUSY QCD corrections and s-quark loops now The QCD corrections due to gluino exchange are not yet included

Next steps: •redo the cross section grids in the Yellow Report•compare to the results of Harlander et al

R.V. Harlander, F. Hofmann, H. Mantler JHEP 1102 (2011) 055

arXiv:1101.0593 [hep-ph]


Neutral Higgs: associated b productionNeutral Higgs: associated b productionNeutral Higgs: associated b productionNeutral Higgs: associated b productionDominant Higgs production process

at high values of tan

4FS

5FS

Exclusive with four active parton flavoursCalculation available at NLO 4FSS. Dittmaier, M. Kramer, M. Spira Phys. Rev. D 70, 074010 (2004)S. Dawson, C.B. Jackson, L. Reina, D. Wackeroth Phys. Rev. D 69, 74027 (2004)

private code – official release in preparationScale uncertainty: 25 - 30 %

Approximation: start with at LOAt NNLO contributesin the real correctionsCalculation available at NNLO 5FSR.V. Harlander, W.B. Kilgore Phys. Rev. D 68, 013001 (2003)

BBHATNNLOScale uncertainty: 10 % for MH> 200 GeVPDF uncertainty: < 10 % for MH < 600 GeV


Neutral Higgs: associated b production Neutral Higgs: associated b production Neutral Higgs: associated b production Neutral Higgs: associated b production First consistent comparison between the 4FS and 5FS calculation

schemes

Bottom pole mass (MSTW2008)

4FS: scale5FS: scale + PDF&S

4FS: scale5FS: scale + PDF&S

MSTW2008 4FS PDF: error sets not available at the time of the studyMS bottom mass:


30 %

Scalar Higgs

Pseudoscalar Higgs


Neutral Higgs: associated b productionNeutral Higgs: associated b productionNeutral Higgs: associated b productionNeutral Higgs: associated b production

5FS: 4FS:

Variations gives maximal/minimal cross sectionsarXiv:1101.0593 [hep-ph]

Scale uncertainty

PDF+S uncertainty


MSSM Neutral Higgs MSSM Neutral Higgs Cross Section SummaryCross Section SummaryMSSM Neutral Higgs MSSM Neutral Higgs

Cross Section SummaryCross Section Summarytan = 5 tan = 30mhmax scenario


bb from ggH@NNLO (5FS)Scaled by (gb

MSSM/gbSM)2 from FeynHiggs


Santander Matching: 4FS & 5FS bbHSantander Matching: 4FS & 5FS bbHSantander Matching: 4FS & 5FS bbHSantander Matching: 4FS & 5FS bbHR. Harlander, M. Krämer, M. Schumacher CERN-PH-TH/2011-

134

Difference between 4FS & 5FS is logarithmic- Large Higgs mass: 5FS more reliableas it resums collinear logs ln(MH/mb)

• use 5FS for mH→∞- For small logs [ln(MH/mb)=2] 4FS dominates

arbitrary choice

Common approach for ATLAS/CMS results


CMS & ATLAS: MSSM Neutral Higgs CMS & ATLAS: MSSM Neutral Higgs exclusion in tanexclusion in tan – M – MAA plane plane

CMS & ATLAS: MSSM Neutral Higgs CMS & ATLAS: MSSM Neutral Higgs exclusion in tanexclusion in tan – M – MAA plane plane

arXiv:1107.5003 [hep-ex]

CMS-PAS-HIG-11-009 1.1 fb-1

36 pb-1

CMS: theoretical band in observed limitATLAS: theoretical uncertainty usedin limit setting procedure

More luminosity: larger reach in MA

CMS restricticts to tan< 60

Higgs→search

Santander matching used


Charged Higgs Production MechanismCharged Higgs Production MechanismCharged Higgs Production MechanismCharged Higgs Production Mechanism

• top quark decay

• Associated production

Two main production mechanism at the LHC

Suppressed modes:


Light Charged Higgs Production: tLight Charged Higgs Production: t→b→bHH±±Light Charged Higgs Production: tLight Charged Higgs Production: t→b→bHH±±

Good agreement between FeynHiggs & CPsuperHexcept for small values of mu, high tan and small MH±

mu: Higgs mixing parameter

mhmax scenario

FeynHiggs 2.7.3S. Heinemeyer, W. Hollik, and G. Weiglein - Comput. Phys. Commun. 124 (2000) 76 - Eur. Phys. J. C9 (1999) 343G. Degrassi et al. Eur. Phys. J. C28 (2003) 133–143M. Frank et al., JHEP 02 (2007) 047

CPsuperH 2.2J. S. Lee et al.- Comput. Phys. Commun. 156 (2004) 283- Comput. Phys. Commun. 180 (2009) 312

t→H±b also included in HDECAYA. Djouadi, J. Kalinowski, and M. Spira, Comput. Phys. Commun. 108 (1998) 56Not included in the comparison FeynHiggs:

CPsuperH:



Heavy Charged Higgs Production: Heavy Charged Higgs Production: pppp→tb→tbHH± ± in the 4FSin the 4FS


Calculation available at NLO QCD 4FSJ. Diaz-Cruz and O. A. Sampayo, Phys. Rev. D50 (1994) 6820F. Borzumati, J. Kneur, and N. Polonsky, Phys. Rev. D60 (1999) 115011 D. Miller, S. Moretti, D. Roy, and W. Stirling Phys. Rev. D61 (2000) 055011S. Dittmaier, M. Krämer, M. Spira, and M. Walser, arXiv:0906.2648 [hep-ph]

LO diagrams

tan = 30

SUSY QCD corrections taken into account rescaling bottom couplings:mb tan mb tanbb

tan = 30

MSTW2008 PDF 4F & 5F consistent resultsUsed 5F for predictions and uncertaintiesas 4F error sets were not available

Scale variation: factor 3

4FS


private code




PDF and S uncertainty not computed!

tan = 30

LO diagram:

NLO corrections to:

Calculation available at NLO QCD 5FSE. L. Berger, T. Han, J. Jiang, and T. Plehn, Phys. Rev. D71 (2005) 115012T. Plehn, Phys. Rev. D67 (2003) 014018C. Weydert et al., Eur. Phys. J. C67 (2010) 617

MC@NLO

5FS

MSTW 5F PDF

Scale variation: factor 3

4FS.vs.5FS



44thth generation SM: Higgs production generation SM: Higgs production44thth generation SM: Higgs production generation SM: Higgs production

• The same theory uncertainty of SM ggF (±15-20% for scale & PDF+αs) • Add ±10% theory uncertainty for missing EW corrrections

Unitarity arguments: MQ4< 500 GeV Marciano, Valencia, Willenbrock, Phys.Rev. D 40 (1989) 1725

Interesting range: M between 400-600 GeV G. Kribs, et al, Phys. Rev. D76 (2007) 075016

MD4=ML4=600 GeVMU4 - MD4 = [ 1 + 1/5*ln(MH/115) ] * 50 GeV

HIGLU

Cross Section calculation at NLO QCD: HIGLU, BR: HDECAY

G. Kribs, T. Plehn, M. Spannowsky, T. Tait, Phys. Rev. D76 (2007) 075016N. Schmidt, S. Cetin, S. Istin, S. Sultansoy, Eur. Phys. J. C66 (2010) 119C. Anastasiou, R. Boughezal, R. Furlan, JHEP 1006 (2010) 101Q. Lin, M. Spira, J.Gau, C.S. Li, Phys. Rev. D83 (2011) 094018X. Ruan, Z. Zhang arXiv: 1105.1634 [hep-ph]A. Rozanov, M. Vysotsky, Phys. Lett. B700 (2011) 313

SM4

Enhanced ggH cross section


44thth generation SM: Branching Ratios generation SM: Branching Ratios44thth generation SM: Branching Ratios generation SM: Branching Ratios

SM 4th generation SMHDECAY

HDECAY v 4.0M. Spira, Fortschr. Phys. 46 (1998) 203A. Djouadi, J. Kalinowski, and M. Spira, Comput. Phys. Commun. 108 (1998) 56A. Djouadi, J. Kalinowski, M. Muhlleitner, and M. Spira, The Les Houches 2009 proceedings

Enhanced gg BR


44thth generation SM:Cross Sections generation SM:Cross Sections44thth generation SM:Cross Sections generation SM:Cross Sections

SM 4th generation SMHIGLU+HDECAY

HIGLU D. Graudenz, M. Spira, and P. Zerwas, Phys. Rev. Lett. 70 (1993) 1372M. Spira, A. Djouadi, D. Graudenz, and P. M. Zerwas, Nucl. Phys. B453 (1995) 17

Enhanced WW/ZZ cross sections


Fermiophobic Higgs: Branching RatiosFermiophobic Higgs: Branching RatiosFermiophobic Higgs: Branching RatiosFermiophobic Higgs: Branching Ratios

• EW radiative corrections unknown in fermiophobic scenario, assign ± 5 %• Higgs production cross sections: NNLO VBF & WH/ZH calculation can be used

fermiophobic

HDECAY

SM

HDECAY v 4.0M. Spira, Fortschr. Phys. 46 (1998) 203A. Djouadi, J. Kalinowski, and M. Spira, Comput. Phys. Commun. 108 (1998) 56A. Djouadi, J. Kalinowski, M. Muhlleitner, and M. Spira, The Les Houches 2009 proceedings

Enhanced BR


Fermiophobic Higgs: Cross SectionsFermiophobic Higgs: Cross SectionsFermiophobic Higgs: Cross SectionsFermiophobic Higgs: Cross Sections

• EW radiative corrections unknown in fermiophobic scenario, assign ± 5 %• Higgs production cross sections: NNLO VBF & WH/ZH calculation can be used

SM

fermiophobic

HIGLU+HDECAY

HIGLU D. Graudenz, M. Spira, and P. Zerwas, Phys. Rev. Lett. 70 (1993) 1372M. Spira, A. Djouadi, D. Graudenz, and P. M. Zerwas, Nucl. Phys. B453 (1995) 17

Enhanced cross section


SummarySummarySummarySummary•Great progress on the theoretical side which have allowed the LHC experiments to use state-of-the-art calculations forthe inclusive cross sections and branching ratios on Higgs production beyond the Standard Model

•The LHC Higgs Cross Section Group has provided a framework which allows to agree on input parameters,PDF, scale and alphas uncertainties which are used bothby ATLAS and CMS. This will make the future combinationof the Higgs limits/discovery easier

•Next challenge is to establish the best NLO MC to performexclusive selections and determine acceptance corrections [eg. introduction of b-tagging in the study of bbH production We need a bbH MC with finite b-quark pT ! ]

•bbZ observables under study to distinguish between 4FS/5FS

BACKUPBACKUPBACKUPBACKUP


MC Generator wish-listMC Generator wish-listMC Generator wish-listMC Generator wish-list

• How to generate (bb)H for inclusive and exclusive studies in the best way

• It would be nice to have the process gb→bH in MC@NLO gg(qqbar)→ttH was implemented recently

• Implementation of virtual corrections via MENLOPS in SHERPA for 1) bb→H and 2) gb→bH

• Study of acceptance corrections for bbH, H→ with SHERPA

• How to generate gg→H including b-quark corrections. So far all generators use the effective ggH vertex only. The pt spectrum of the Higgs boson might be signifcantly softer for large b-H coupling. Implement this in SHERPA?

M. Schumacher


Search for Charged Higgs: tSearch for Charged Higgs: t→→HH±±bbSearch for Charged Higgs: tSearch for Charged Higgs: t→→HH±±bb

ATLAS 35 pb-1

Assuming:

Assuming:

High tan

Low tan

CMS 1 fb-1

CMS 1 fb-1


bbZ ProductionbbZ Production: : benchmark for 4FS and 5FS calculationsbenchmark for 4FS and 5FS calculations

bbZ ProductionbbZ Production: : benchmark for 4FS and 5FS calculationsbenchmark for 4FS and 5FS calculations

Madgraph+Pythia

Fixed flavour: 4FS NLODittmaier, Kramer, Spira, Dawson, Jackson, Reina, Wackeroth•massive b•2 b (no extra jets)•1 b with pt > 15 GeV

Variable Flavour: 5FS NLOmassless b Campbell, Ellis, Maltoni, Willenbrock•massless b•Inclusive Z+jets (MLM matching with up to 4 jets)Cross sections from MCFM (5FS)

Measurement of:•total cross section•pt of the Z and bwill be used

MC describes well the data

Cross sections available in:MCFM (5FS)MC@NLO (4FS)


MSSM: mMSSM: mhhmaxmax scenario scenarioMSSM: mMSSM: mhhmaxmax scenario scenario

• Mtop= 172.5 GeV

• mb(mb) MSbar= 4.213 GeV

• S(MZ)=0.119

• MSUSY = 1000 GeV

• Xt = 2000 GeV

• M2 = 200 GeV• = 200 GeV• M3 = 800 GeV

SU2 gaugino mass parameter

gluino mass parameter

Higgs mixing parameter

stop mixing parametersoft SUSY-breaking squark mass

Susy loop corrections arenegligible in this scenario


HIGLU: Standard Model ParametersHIGLU: Standard Model ParametersHIGLU: Standard Model ParametersHIGLU: Standard Model Parameters

• S (MZ)= 0.12018 2 loop

• QCD= 226 MeV

• PDF: MSTW2008nlo68cl

• Mcharm = 1.40 GeV

• Mbottom = 4.75 GeV

• Mtop = 172.5 GeV

• GF = 1.16637 10-5 GeV-2

• MZ = 91.1876 GeV

• MW = 80.398 GeV


Yukawa Couplings: Yukawa Couplings: bb corrections from Feynhiggs corrections from Feynhiggs

Yukawa Couplings: Yukawa Couplings: bb corrections from Feynhiggs corrections from Feynhiggs

M. Spira

mhmax scenario: b corrections to the b Yukawa coupling

are smaller than 10 %


Heavy Higgs Cross Section Heavy Higgs Cross Section Heavy Higgs Cross Section Heavy Higgs Cross Section

Deviations wrt zero-width approximationare +30% -20% difference in cross sectionfor MH< 600 GeV

Default option in iHixs

Seymour option in iHixsResummation of VV→VV

scatteringImproved s-ch approximation

C. Anastasiou, S. Buehler, F. Herzog, A. Lazopoulos, arXiv:1107.0683

developments on cross-section and br of higgs production: part 2 bsm

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