Measuring the Higgs Quantum Numbers

Transcription

1 Measuring the Higgs Quantum Numbers to appear on hep/ph next Wednesday IMPRS seminar 3.. Dorival Gonçalves Netto in collaboration with C. Englert (Durham U.), K. Mawatari (Vrije U. Brussel) & T. Plehn (U. Heidelberg) ITP - Universität Heidelberg

2 Motivation ATLAS and CMS reported discovery of a Higgs-like resonance with mass ~6 GeV How can we know that it is really the Higgs boson? We need to confirm the structure of the Higgs Lagrangian from the data. Check the Spin and CP nature Check the operator basis Then measure its couplings to the other particles We propose to determine the coupling structure, spin and CP nature using angular correlations via WBF (and associated ZH production).

3 Higgs Production at the LHC

4 Lagrangian Spin zero: L = g () HV µ V µ g () 4 HV µ V µ g () 3 4 AV e µ V µ g () 4 4 HG µ G µ g () 5 4 AG e µ G µ CP even and odd scalars X = H, A; V = W, Z and G = gluon

5 Lagrangian Spin zero: L = g () HV µ V µ g () 4 HV µ V µ g () 3 4 AV e µ V µ g () 4 4 HG µ G µ g () 5 4 AG e µ G µ CP even and odd scalars X = H, A; V = W, Z and G = gluon Spin one: L = ig () (W µ W µ W µ W µ ) Y (e) ig () W µ W Y (e)µ g () 3 µ (W W )Y (e) ig () 4 W µw µ Y (e) g () 5 W µ W (@ µ Y Y (o)µ )ig () 6 W µ W Y e (o)µ ig () 7 W µw µ Y e (o) g () 8 µ Y (e) µ Z (@ Z )g () 9 Y (o) µ (@ Z µ )Z. Spin two: L = g () G µ T µ V g () G µ T µ G g () 3 G µ T µ f

6 Models

7 Hadron collider observables The momentum of a produced particle is expressed by the polar angle θ and the azimuthal angle Φ from the collision point, where the z-axis is taken along the beam axis. Rapidity η is often used instead of θ: η=-/ ln tan(θ/) η θ 9 (central region) η.5 θ (forward region)

8 Hadron collider observables The momentum of a produced particle is expressed by the polar angle θ and the azimuthal angle Φ from the collision point, where the z-axis is taken along the beam axis. Rapidity η is often used instead of θ: η=-/ ln tan(θ/) η θ 9 (central region) η.5 θ (forward region)

9 Hadron collider observables VBF distinctive jet Kinematics: VBF : q q! j j (X! d d) { mn, mn} for m, n = j,,x,d, d

10 Tagging jet kinematics σ dσ dη X dσ σ dη j σ dσ dp Tj SM D5 - D5 EW EWq η X -4-4 η j 5 5 p Tj Central X production Spin- forward tagging jets Spin- central tagging jets Spin- PT go beyond the TeV scale. Consistent models will include a form factor to cut this tail

11 Contaminating sub-process for WBF GF WBF gg sum.5.5 qq 5 qg 5 5 m min [GeV] m > 6 GeV Gluon fusion is suppressed to 5% Jet veto reduces it to %

12 Tagging jet kinematics spin- spin- spin- spin- PTj>GeV.6.4 d d SM D5 - D5 D5(g) - D5(g).6.4 Z W - Z - W.6.4 EW EWq QCD Δφ 4 6 Δφ 4 6 Δφ 4 6 Δφ d d d d constant cos d d cos Plehn, Rainwater, Zeppenfeld ()

13 Tagging jet kinematics spin- spin- spin- spin- PTj>GeV Δη Δη Δη Δη In our analysis we avoid the standard WBF cut > 4. This makes our set of observables more powerful to distinguish the hypothesis Spin-, in contrary to the spin-, does not present a large rapidity gap The cut P Tj > GeV selects the same helicity state as the spin-

14 Higgs-jet correlations spin- spin- spin- spin- PTj>GeV.5 SM D5 - D5 D5(g) - D5(g).5 Z W - Z - W.5 EW EWq QCD Δφ jx 4 6 Δφ jx 4 6 Δφ jx 4 6 Δφ jx Requires reconstruction of the heavy resonance: X! most promising channel X! approximate reconstruction

15 Higgs-jet correlations.3 spin- spin- spin- spin- PTj>GeV Δη jx Δη jx Δη jx Δη jx Requires reconstruction of the heavy resonance: X! most promising channel X! approximate reconstruction

16 Basic strategy

17 Comparison of observables Confidence level for distinction from the SM hypothesis. SM vs. D5 SM vs. D5 SM vs. EWq confidence level η φ 95% CL η jx φ jx confidence level η 95% CL η jx φ jx φ confidence level η φ 95% CL η jx φ jx σ limit 7 5σ limit 7 5σ limit luminosity L [/fb] luminosity L [/fb] luminosity L [/fb] 6 8 Makes the analysis competitive with the standard X! ZZ Most powerful observables: and It is essential avoiding the standard rapidity gap cut for WBF in this analysis

18 Comparison of observables Confidence level for distinction from the SM hypothesis. SM vs. D5 SM vs. D5 confidence level η φ 95% CL η jx φ jx confidence level η 95% CL η jx φ jx φ σ limit 7 5σ limit luminosity L [/fb] luminosity L [/fb] dσ σ dδφ SM D5 - D5.3. σ dσ dδη Δφ Δη

19 Summary After the Higgs discovery the main challenge is to confirm its Lagrangian We present a comprehensive study of the determination of it in WBF Most powerful observables: and It is required very low luminosity to distinguish the hypothesis fb The analysis is competitive with the standard X! ZZ

20 Nelson angles X! ZZ! 4l.5 ê z j e e p p X ` µ µ µ.4.3 dγ Γ dδφ j e e h Z ê z? Z p p µ µ.. - D5 D5 SM Nelson angles (standard approach): S.Y.Choi, Miller, Muhlleitner, Zerwas, PLB(3) Y. Gao, A. Gritsan, Z. Guo, K. Melnikov, M. Schulze, N. Tran ()

21 Flipped Nelson VBF : q q! j j (X! d d) ( Q V d j dσ σ dδφ - D5 V ( Q? j. D5. SM Flipped Nelson angles: It assumes the completely reconstruction of the hard process Not well suited for dealing with QCD effects at a Hadron Collider