Calculations of Higgs x-sections at NkLO ATL-COM-PHYS-2009-161 A.-C. Bourgaux, M. Escalier, L. Fayard

Tools and parameters used Anastasiou Tools: FEHiP, HggTotal, HNNLO, HqT Factorisation (µF) and renormalisation (µR) scales : mF= mR in [mH/2 ; 2mH ] to limit computations (study in appendix) Pdf: mstw2008, (mrst 2004 for HqT) (study in appendix) default parameters used, while waiting for a common prescription: mt = 172.7 GeV for FEHiP, 178 GeV for HNNLO (study in appendix)

Total x-sections (100-800 GeV) • HNNLO mt  ∞ No correction • FEHiP mt  ∞ + correction: Opening of the on-shell phase-space Result table, approx of ∞ mass t; b  appendix

Total x-sections with HggTotal Available : http://www.phys.ethz.ch/~babis/Software/ Good agreement with calculations by De Florian and Grazzini, with a different choice for mR and mF. Anastasiou : arXiv:0811.3458, arXiv:hep-ph/0207004 "We present results for the Higgs boson cross section accounting for these effects. We account for the effect of soft-gluon resummation at the Tevatron by presenting values for the scale choice µF = µR = MH /2, which is known to very accurately reproduce the reference value of the resummation result [21] for a wide range of Higgs boson masses, and provide an estimate of the remaining theoretical uncertainties arising from unknown higher-order terms and PDF errors."

x-sections*BR with HNNLO s × Br(H  gg) Br(H  gg) (Br tables of HNNLO seem to be computed from Hdecay)

differential x-sections with HNNLO 5 (jet) 1 3 H 4 6 (jet) 2 gg fusion Higgs 2 photons γ LO _ pT34 pT3 &pT4 y34 η3 & η4 NLO pT5 pT34 pT3 &pT4 NNLO pT5 pT34 pT3 & pT4 pT6 y34 η3 & η4

ATL-COM-PHYS-2009-161 Qian, Liu, Mansoulie, Purdham, Strandberg, Thun photon g mH=100 GeV mH=800 GeV For high masses, the photon is more central normalized: stable observable / pert order mH=100 GeV ATL-COM-PHYS-2009-161 Qian, Liu, Mansoulie, Purdham, Strandberg, Thun

photon g mH=100 GeV fixed order calculation : LO bounded at pt=mH/2  NLO and NNLO unstables in this region normalized: ATL-COM-PHYS-2009-161

Higgs mH=100 GeV mH=800 GeV normalized: stable observable / pert order ATL-COM-PHYS-2009-161 Detector acceptance will limit the rapidity range that can be measured

Higgs compatible with statistical error mH=100 GeV ATL-COM-PHYS-2009-161

PT of Higgs : HqT Construction of the curve : Resummed : divergent terms only « resummed »=exp(Sudakov factor) Asymptotic : limit of perturbative order when PT0 : divergent terms only Fix order : all perturbative developpement terms, including divergent terms Matched = Resummed + Fix order - Asymptotic

Higgs PT, @ LO and NLO mH=125 GeV Normalized : ≠ from HNNLO Correction to pT(H) : appendix

resummation for low pT fix order for high pT HqT HNNLO

Influence of mR , mF at LO linear scale: log scale: with normalization:

Influence of mR , mF at NLO (1) linear scale: log scale: with normalization:

Influence of mR , mF at NLO (2) For high pT : dependance on scales remains almost constant : calculation is actually LO For low pT : dependance on scales decreases between LO and NLO NLO mH/2

Influence of resummation scale mRS at LO (1) mRS=mH Matched calculation is closer to fix order when resumation scale is lower

Influence of mRS at LO (2) linear scale: log scale: with normalization:

Influence of mRS at NLO (1) Resumation scale influence is lower at NLO

Influence of mRS at NLO (2) linear scale: log scale: with normalization:

Acceptances with FEHiP, PYTHIA and MC@NLO

Appendix

Approximation of infinity mass of t ; b Plot from Frank Petriello ?!? http://agenda.hep.wisc.edu/getFile.py/access?contribId=9&resId=0&materialId=slides&confId=189

Influence of µF µR Major effect: σ decreases with µR   maximum central value minimum mH=120 GeV mH=190 GeV mF 0.5 1 2 mR 14.7 15.02 15.10 5.98 5.87 5.71 11.8 12.02 12.10 4.86 4.77 4.64 9.62 9.84 9.91 4.03 3.95 3.85 Influence of µF µR Major effect: σ decreases with µR Minor effect: σ increases or decreases with µF depending on mass @ LO (same observations at NLO…), using mrst2001 Complete study in appendix

Influence of mt FEHiP mt  ∞ HNNLO + correction: mt  ∞ without correction mt : little influence HNNLO and FEHiP differences due to F(mt)

Our results with FEHiP: Influence of pdf Our results with FEHiP: mrst2001 mstw2008 +14% LO, 100 GeV: 17,159 19,467 +6% NLO, 100 GeV 31,117 33,005 With HNNLO: mrst2002 mstw2008 +13% LO, 100 GeV 16,507 18,704 +8% LO, 200 GeV 3,632 3,937 Results compatible with: Martin,Stirling,Thorne,Watt, arXiv:0901.0002v2 +10%

Check of constistency: 2 equivalent photons ? (no cuts applied at generation) m=100 GeV

What is the uncertainty on PT(H)? Balazs, Grazzini, Huston, Kulesza,Puljak arXiv:hep-ph/0403052v1

Corrections to pT(H) Finite top quark mass ; Bottom quark contribution Keung, Petriello, hep-ph 0905.2775 Finite top quark mass ; Bottom quark contribution LHC : 30 ≤PT≤50 GeV : -4 % 50≤PT≤150 : % PT~300 GeV : -30 %

EW gauge boson terms (W, Z) Keung, Petriello, hep-ph 0905.2775 EW gauge boson terms (W, Z) LHC : 100≤PT≤300 GeV : -3 %

Prescription used for ATL-COM-PHYS-2007-024 Should we use same prescription ? Arguments for prescription ?

EW corrections 2-loop EW corrections for Hgg : eg of production corrections eg of decay corrections

-top quark contributions : ~15 % of light contribution Degrassi, Maltoni, hep-ph/0407249 Total : 5-8 % correction contrib. of top

-light fermions contributions Aglietti, Bonciani, Degrassi, Vicini, hep-ph/0404071 production decay QCD total EW (no top correction) 9 % to LO up to –10 % correction