Status of Higgs plus one jet at NNLO

Transcription

1 Status of Higgs plus one jet at NNLO Matthieu Jaquier Physics Institute University of Zürich Radcor-Loopfest UCLA 7 th June 205 Based on work with X. Chen, T. Gehrmann and E.W.N. Glover Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, 205 / 20

2 Introduction Introduction Higgs boson discovered [Atlas collaboration 202, CMS collaboration 202], what next? Establish if it is the SM Higgs boson or something else. Investigate its coupling to other SM particles. This requires a very good theoretical knowledge of the new particles s behaviour, in particular its p T spectrum. Understand how the signal behaves under jet cuts, as are applied for H WW via VBF to supress t t background [Atlas collaboration 202, CMS collaboration 202]. Jet substructure techniques to access H b b decays [Butterworth, Davison, Rubin, Salam 2008]. Also: better understanding of jet binning in H WW. Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

3 Introduction Introduction Where do we stand? m t H + J at NLO [De Florian, Grazzini, Kunszt 999, Ravindran, Smith, Van Neerven 2002, Glosser, Schmidt 2002] in Higgs effective field theory (HEFT) [Wilczek 977, Shifman, Vainshtein, Zakharov 978, Inami, Kubota, Okada 083] with finite m t effects [Harlander, Neumann, Ozeren, Wiesemann 202]. H + J at NNLO in HEFT [Boughezal, Caola, Melnikov, Petriello, Schulze 205, Boughezal, Focke, Giele, Liu, Petriello 205] We provide a computation of purely gluonic (N f = 0) H + J at NNLO in HEFT. This is expected to contribute by 60% to the total cross section. Independent crosscheck One of the first NNLO processes done with several different subtraction formalisms Opportunity for benchmarking Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

4 Introduction IR subtraction at NNLO dˆσ ij,nnlo = [dˆσ ij,nnlo RR dˆσs ij,nnlo ] dφ n+2 + [dˆσ ij,nnlo RV dˆσt ij,nnlo ] dφ n+ + [dˆσ ij,nnlo VV dˆσu ij,nnlo ] dφ n Subtraction schemes are: Antenna subtraction [Gehrmann-De Ridder, Gehrmann, Glover 2007, Kosover 998], q T -subtraction [Catani, Grazzini 2007], Residue subtraction [Frixione, Kunszt, Signer 996], Sector decomposition [Binoth, Heinrich 2000], STRIPPER [Czakon, Heymes 204] and N-Jettiness [Boughezal, Focke, Liu, Petriello 205, Gaunt, Stahlhofen, Tackmann, Walsh 205]. Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

5 Antenna subtraction Structure of the subtraction terms at NLO Real subtraction term includes X3 0 (i, j, k) M(0) n (..., I, K,...) 2 J n (..., I, K,...). Integrated subtraction term contains where X3 0 (i, j) M(0) n (..., i, j,...) 2 J n (..., i, j,...) dz dz 2 ( z z Γ(z 2 )δ( z 2 ) + ( 2) ) M n (0) (z p, z 2 p 2,...) 2 J n (...). X3 0 (X 3 0 ) are the unintegrated (integrated) 3-parton 0-loop antenna funtions. The mapping (i, j, k) (I, K) interpolates between singular limits. J n is the measurement function selecting n jets. Γ is the mass factorisation kernel. Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

6 Antenna subtraction Structure of the subtraction terms at NLO Recently, progress has been achieved in understanding the structure of the integrated subtraction terms [Currie, Glover, Wells 203]: X 0 3 (I, J) = J () 2 (I, J), X 0 3 (, I ) + Γ(z ) = J () 2 (, I ), X 0 3 (, 2) + Γ(z )δ( z 2 ) + Γ(z 2 )δ( z ) = J () 2 (, 2), and J () 2 (I, J) = I () 2 (I, J) + Finite, where I () 2 (I, J) is catani s IR singularity operator. This correspondence might allow an automatisation of NNLO subtraction starting from the known IR behaviour of loop amplitudes! Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

7 Antenna subtraction Additional features at NNLO At RR: X3 0 (i, j, k) M(0) n+ (..., I, K,...) 2 J n+ (..., I, K,...) X4 0 (i, j, k, l) M(0) n (..., I, L,...) 2 J n (..., I, L,...) X3 0(i, j, k)x 3 0 (I, K, l) M(0) n (..., I, L,...) 2 J n (..., I, L,...) At RV: J () (i, j) M (0) n+ (..., i, j,...) 2 J n+ (..., i, j,...) X3 0 (i, j, k) M() n (..., I, K,...) 2 J n (..., I, K,...) X3 (i, j, k) M(0) n (..., I, K,...) 2 J n (..., I, K,...) At VV: J (2) (i, j) M n (0) (..., i, j,...) 2 J n (..., i, j,...) J () (i, j) M () n (..., i, j,...)m (0) n (..., i, j,...) J n (..., i, j,...) J () (i, j) 2 M (0) n (..., i, j,...) 2 J n (..., i, j,...) Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

8 Antenna subtraction Performance of the subtraction terms s a e-06 e-08 e s b e-06 e-08 e s a e-06 e-08 e s b e-06 e-08 e s a e-06 e-08 e s b e-06 e-08 e s 34 s 35 s e-06 e-06 e-06 e-08 e-08 e-08 e-0 e-0 e Distribution of subtracted RR weight versus partonic phase-space variables Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

9 Implementation Technicalities Computation for 8TeV LHC Gluons only Use NNPDF23 set VEGAS integration coded up in FORTRAN Higgs decay matrix element included Production of user defined distributions Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

10 Implementation Comparison with ATLAS We use m H = 25GeV Anti-k T jet algorithm R=0.4 Jet p T cut at 30GeV, Jet η cut at 4.4 Leading/Subleading photon p T cut at 0.35/0.25 m γγ Photon η cut at 2.37 Jγ < GeV < m γγ < 6GeV Photon isolation and hadronisation corrections estimated from MC [ATLAS 204] Correction to H γγ branching ratio included. Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

11 Results Comparison with ATLAS channel cross section [fb] approx. processor time tree 5.8 ± min virt ± min real ± h VV 4.25 ± min RV ± h RR.004 ± h + 4 days warmup (2 cores) σn LO = fb σn NLO = fb σn NNLO = fb, To be compared with σn ATLAS = 2.5 ± 5.3(stat.) (syst.) ± 0.6(lumi) [ATLAS 204] Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, 205 / 20

12 Results σn LO = fb σn NLO = fb σn NNLO = fb. We set H T as central scale and vary it by factors of 2 and 2 the error from missing higher orders. to estimate µ R,µ F m H /2,m H /2 m H /2,2m H m H,m H 2m H,m H /2 2m H,2m H σn LO σn NLO σn NNLO Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

13 Results p T Distributions: diphoton system (preliminary).5 ATLAS NLO theory NNLO theory gg only dσ/dp T [fb/gev] p T γγ [GeV] Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

14 Results p T Distributions: leading jet (preliminary) dσ/dp T [fb/gev] ATLAS NLO theory NNLO theory gg only p T j [GeV] Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

15 Results p T Distributions: subleading jet (preliminary) ATLAS NLO theory NNLO theory gg only dσ/dp T [fb/gev] p T j2 [GeV] Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

16 Results η Distribution of the leading jet (preliminary) ATLAS NLO theory NNLO theory gg only dσ/d η [fb] η j Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

17 Results H T Distribution (preliminary) 0.8 ATLAS NLO theory NNLO theory gg only dσ/dh T [fb/gev] H T [GeV] Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

18 Results cos(θ) Distribution (preliminary) ATLAS NLO theory NNLO theory gg only dσ/d cos(θ) [fb] cos(θ) Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

19 Conclusions Conclusions and outlook We presented a computation of gg H + J at NNLO QCD in HEFT. The handling of IR divergences is successfully carried out by the antenna subtraction formalism. We achieve agreement with existing results. We implemented the setup of ATLAS and compare distributions with experimental results. The next step(s) consist in evaluating the remaining qg and q q channels to obtain full results. Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20

20 Conclusions Thanks! Matthieu Jaquier (Physics Institute UZH) Status of Higgs plus one jet at NNLO June 7, / 20