12 March 2014 Liverpool High Energy Theory Group

Transcription

1 ELECTROWEA HIGGS BOSON PRODUCTION IN ASSOCIATION WITH THREE JETS (A..A. VBF + JET) AT QCD IN COLLABORATION WITH S. PLATZER, F. CAMPANERIO, AND M. SJODAHL! PRL, 2802, (203), ARXIV:3.5455! Dr. Terrance Figy NAFUM Research Associate The University of Manchester! 2 March 204 Liverpool High Energy Theory Group!!

2 OUTLINE Introduction Some Details The Results Outlook

3 Happy Higgsdependence Day! I think we have it -Rolf-Dieter Heuer, 4 July 202 ATLAS-CONF CMS-PAS-HIG T. Figy H 0 production via VBF

4 SM Higgs boson Spontaneous Symmetry Breaking: SU(2) L U() Y U() em SM Higgs Doublet Φ = U(x) ( ) 0 2 v + H The remormalizable Lagrangian L = D µ Φ 2 + µ 2 Φ Φ λ(φ Φ) 2 leads to the vacuum expectiation value v = field H. µ 2 λ for the Higgs

5 SM Higgs boson Higgs couplings to fermions Fermion ( masses arise from Yukawa couplings via Φ 0, v+h 2 ). L Yukawa = f m f ff ( + H v ) Test SM prediction: ffh Higgs coupling strength = mf /v Observation of Hf f Yukawa coupling is no proof that a v.e.v exists

6 SM Higgs boson Higgs couplings to gauge bosons inetic energy term of the Higgs doublet field: (D µ Φ) (D µ Φ)= 2 µ H µ H [ (gv 2 ) 2W µ+ W µ (g 2 + g 2 )v 2 4 Z µ Z µ ]( + H v ) 2 W,Z mass generation: mw 2 = ( ) gv 2 2, m 2 Z = ( g 2 +g 2 )v 2 4 WWH and ZZH couplings are generated:coupling strength =2mV 2 /v g 2 v within SM

7 Total SM Higgs cross sections at the LHC H H H t W, Z H t

8 Vector Boson Fusion Event Characteristics Energetic jets in the forward and backward directions (p T > 20 GeV) Higgs decay products between tagging jets Little gluon radiation in the central-rapidity region, due to colorless W /Z exchange (central jet veto: no extra jets with p T > 20 GeV and η < 2.5)

9 Vector Boson Fusion Central Jet Veto Example: Gluon fusion vs vector boson fusion JHEP 05 (2004) 064 y rel = y veto j (y tag j + y tag 2 j )/2

10 Hjjj via VBF at (only t-channels) Total Cross section No pentagon or hexagon diagrams included. Approximate as two DIS reactions. µ 0 =40GeV ξ =2 scale variations: : +26% to 9% : less than 5% JHEP 0802 (2008) 076 [arxiv: ]

11 COMMENTS ON VBF POWHEGBOX [ARXIV: ] p S = 4 TeV mh = 20 GeV Figure 6: Transverse momentum (p j 3 T ) distribution of the third azimuthal-distance distribution of the two tagging jets, φ jj (right

12 THIS WOR (HJETS++) Our aim was to compute the missing pieces (s, t,and u-channel one-loop amplitudes) in H+3 Jets production where the Higgs boson is produced via the HVV coupling (a.k.a VBF+Jet). H H H H Virtuals: Hexagons, Pentagons, 2 u u 4 Boxes, and Triangles z h 7 z d~ 6 Reals: H+6 parton amplitudes (6 quark + H, 4 quark + 2 gluons +H) u d~ g d u 5 3

13 σ DIPOLE SUBTRACTION Overview H 0 production via VBF Results ab (p, p) = σ {4} ab (p, p)+σ {3} ab (p, p) cross section: + 0 σ {3} ab (p, p) = dx[ˆσ {3} ab σ 3 Higgs Production via Vector Boson Fusion Dipole subtraction method Catani and Seymour, hep-ph/ (x, xp, p)+ˆσ {3} ab (x, p, x p)] ab (p, p) = σ {4} [dσab V (p, p)+dσb ab (p, + p) I] ϵ=0 Catani and Seymour, hep-ph/ ab dx[ˆσ {3} ab 0 (p, p)+σ {3} ab (p, p) (x, xp, p)+ˆσ {3} ab (x, 0 dx ˆσ {3} ab (x, xp, p) = a 0 dx 3 {dσa B b (xp, p) [P(x)+(x)] aa } ϵ=0 σ {4} ab (p, p) = 4 [dσ R ab (p, p) ϵ=0 dσ A ab (p, p) ϵ=0] For the H+2,3, and 4 jet amplitudes we use the in-house spinor library of Matchbox. T. Figy H 0 production via VBF

14 SOME DETAILS Matchbox [S. Platzer and S. Gieseke, arxiv: ] Catani-Seymour Dipole subtraction [hep-ph/ ] Subtractive and POWHEG style matching to parton shower ColorFull [M. Sjodahl, arxiv:2.2099, ColorMath.htm#ColorMath, ColorFull will soon be public.] Tensorial Reduction [F. Capanario, arxiv: ] Scalar Loop Integrals: Oneop [A. van Hameren arxiv: ]

15 THE RESULTS Input parameters and kinematic cuts. Scale variations for total cross section. inematic distributions.

16 INPUT PARAMETERS Ecm=4 TeV (proton - proton LHC) At least three anti-t D=0.4 (E-scheme recombination) of 20 GeV and rapidity within -4.5 and 4.5 using FastJet [arxiv: , arxiv:.6097] PDF choices: CT0 for and CTEQ 6L for [arxiv:hepph/02095, arxiv: ] Scales: W-boson mass (MW) and sum of transverse momentum of reconstructed jets (HT)

17 Scale Variations on Integrated Cross-sections , µ = ξh T, µ = ξm W, µ = ξh T, µ = ξm W µ 0 = H T (M W ) 900 H T = P j p T,j σ/fb = / ξ = µ/µ 0 µ R = µ F = H T /2(M W /2): 30% (24%) at and 2% (8%) at = 520(8) fb = 466(7) + 35 fb

18 JET DISTRIBUTIONS dσ/dy3 [fb] Rapidity of the third jet dσ/dp,3 [fb/gev] Transverse momentum of the third jet Relative position of the third jet y p,3 [GeV] dσ/dz 3 [fb] z 3 z? 3 =(y 3 2 (y + y 2 ))/(y y 2 ) ctor for the p T of the third hardest jet (left) and the normalized et w.r.t. the tagging jets (right). Cuts are described in the text.

19 Rapidity difference of first and second jet Rapidity separation dσ/d y2 [fb] dσ/d y3 [fb] 0 3 Rapidity difference of first and third jet y dσ/d y23 [fb] 0 3 Rapidity difference of second and third jet y y 23

20 Higgs Boson Distributions dσ/dp,h [fb/gev] 0 Transverse momentum of the H dσ/dyh [fb] Rapidity of the H p,h [GeV] y H Transverse momentum Rapidity

21 Higgs Boson Distributions Azimuthal angle separation of H and third jet Rapidity separation of H and third jet dσ/d φ h3 [fb] dσ/d y h3 [fb] φ h3 y h3

22 Jet Masses Mass of the first jet Mass of the second jet dσ/dm [fb/gev] dσ/dm2 [fb/gev] m m 2 Mass of the third jet Here we see fat jets. dσ/dm3 [fb/gev] m 3

23 Distributions with VBF cuts Mass of first and second jet Mass of first and third jet dσ/dm2 [fb/gev] 0 dσ/dm3 [fb/gev] Ratio Ratio m 2 [GeV] m 3 [GeV] Mass of second and third jet m j j 2 > 600 GeV dσ/dm23 [fb/gev] 0 y j j 2 > 4.0 Ratio m 23 [GeV]

24 Distributions with VBF cuts Rapidity difference of first and second jet Rapidity difference of first and third jet dσ/d y2 [fb] dσ/d y3 [fb] Ratio Ratio y 2 y 3 Rapidity difference of second and third jet m j j 2 > 600 GeV dσ/d y23 [fb] y j j 2 > 4.0 Ratio y 23

25 Distributions with VBF cuts Relative position of third jet Transverse momentum of the third jet dσ/dz 3 [fb] dσ/dp,3 [fb/gev] z 3 Ratio p,3 [GeV] Rapidity of the third jet m j j 2 > 600 GeV dσ/dy3 [fb] 0 y j j 2 > 4.0 Ratio y 3

26 OUTO Write a longer paper with more details (study VBF cuts, etc.) Matching to parton shower (angular ordered and dipole shower in Herwig++)

27 Comparison to VBF 2 0 VBF cuts VBF 0 9 VBF cuts VBF 8 d /d p T,3 (fb/gev) d /d p T,3 (fb/gev) p T,3 (GeV) p T,3 (GeV)