Influence of anomalous VVH and VVHH on determination of Higgs self couplings

Transcription

1 , DAE-BRNS High Energy Physics Symposium December 08-12, 2014 Influence of anomalous VVH and VVHH on determination of Higgs self couplings Author: Satendra Kumar Department of Physics Indian Institute of Technology Guwahati Guwahati , India

2 Preamble Introduction and Motivation General Set-up Method and Analysis Results and Discussion Summary and Conclusion 1/26

3 Introduction and Motivation P article content of the standard model(sm) is now complete with therecentdiscoveryofhiggsbosonof massaround GeV,observed by the ATLASand thecmscollaborationsatthelhc. This model describes the universe in terms of elementary particles and their interactions. Itisbasicallyquantumfieldtheoryofgroup. All fundamental particles in the SM, receive their mass through the electroweak symmetry breaking(ewsb) via Higgs mechanism. The more massive a particle, the stronger its interaction with the Higgs boson 2/26

4 Introduction and Motivation Fermions generation generation generation Bosons Leptons Quarks Electron Mass = Charge = -1 Electron-neutrino Mass < Charge = 0 Up-quark Mass = Charge = 2/3 Down-quark Mass = Charge = -1/3 u d Muon Mass = Charge = -1 Particle Muon-neutrino Tau-neutrino content of the SM Mass < Charge = 0 Charm-quark Mass = 1.3 Charge = 2/3 c Strange-quark Mass = 0.1 Charge = -1/3 s Tau Mass = Charge = -1 Mass < 0.02 Charge = 0 Top-quark Mass=175 Charge = 2/3 t Bottom-quark Mass = 4.3 Charge = -1/3 b W-Boson Mass = 80.4 Charge = 1 Spin = 1 Z-Boson Mass = Charge = Spin = 1 Photon Mass = 0 Charge = 0 Spin = 1 Gluon Mass = 0 Charge = 0 Spin = 1 Force Carriers All masses in GeV. 3/26 Charges in terms of e.

5 Introduction and Motivation Fermions generation generation generation Bosons Leptons Quarks Electron Mass = Charge = -1 Electron-neutrino Mass < Charge = 0 Up-quark Mass = Charge = 2/3 Down-quark Mass = Charge = -1/3 u d Muon Mass = Charge = -1 Particle Muon-neutrino Tau-neutrino content of the SM Mass < Charge = 0 Charm-quark Mass = 1.3 Charge = 2/3 c Strange-quark Mass = 0.1 Charge = -1/3 s Tau Mass = Charge = -1 Mass < 0.02 Charge = 0 Top-quark Mass=175 Charge = 2/3 Higgs Boson t Mass Charge = 0 Spin = 0 Bottom-quark Mass = 4.3 Charge = -1/3 b W-Boson Mass = 80.4 Charge = 1 Spin = 1 Z-Boson Mass = Charge = Spin = 1 Photon Mass = 0 Charge = 0 Spin = 1 Gluon Mass = 0 Charge = 0 Spin = 1 Higgs Force Carriers All masses in GeV. 3/26 Charges in terms of e.

6 Introduction and Motivation Leptons Quarks u d c s b t Higgs 4/26

7 Introduction and Motivation Thismodel has great story of success, from several experiments, but still it is silent about various questions. Hierarchy problem Dark Matter Neutrino mass Matter-antimatter asymmetry Answerofsomeofthesequestionshasbeengivenbysomeextensionsof the SM. MSSM, NMSSM, Low energy gravity models, GUTs etc. 5/26

8 Introduction and Motivation DiscoveryofHiggsbosonbytheLHChasestablishedthatEWSBis brought through Higgs mechanism. MassofHiggsbosonisknownquitewell. Spin-Parity measurement favours Spin-0, even parity state. Details are not known yet- OneHiggsormanyHiggs? Exact nature of EWSB potential? Need to understand various couplings precisely. We know: Longitudinal degree of gauge boson originates from Higgs field. It is very exciting time to understand the interaction of Higgs boson with gauge bosons, as well as with itself. StudyofVVV,VVH,VVHHandHHHareveryimportant V = W, Z, 6/26

9 Introduction and Motivation LHCisadiscoverymachine,whileILCisaprecisionmachine. Circular collider LHC Proton-Proton collisions (composite) Initial state: No fixed centre-of-mass energy No beam polarization Hadronic background Linear collider e- e+ collisions (elementary) ILC Fixed centre-of-mass energy Polarized beam facility is available Clean initial state LHCandILCarecomplimentary.Weneedbothmachinesifweareto get to the bottom of the fundamental questions. ILC is more suitable for precision measurements of Higgs and gauge boson couplings. 7/26

10 Introduction and Motivation..aprecisionmachine International Linear Collider 8/26

11 Method and Analysis Model file Higgs Effective Lagrangian Mathematica FeynRules Extracting Feynman rules MadGraph Cross Section, Kinematic Distributions Plots and Analysis 9/26

12 General Set-up The effective Lagrangian with full set of dimension-6 operator involving the Higgs bosons is given in Ref. Adam Alloul et al. JHEP 1404(2014) 110. Higgs sector of the Lagrangian is given by Where,, and are coupling constant of group, and respectively., and are field tensor of group, and respectively. 10/26

13 General Set-up This effective Lagrangian leads to the following in unitary gauge and mass basis. + h.c. + h.c. 11/26

14 General Set-up,,, Various physical couplings present in the above expression are given in terms of the parameters of the effective Lagrangian as -,,,,,, 12/26

15 General Set-up In total eight coefficients,,,,,,,, which governing the dynamics of and production at the ILC Experimental constraints on -conseving parameters from the ATLAS and the CMS along with D0 are.,..,..,..,..,. John Ellis, et al. JHEP 1407 (2014) /26

16 and production at ILC Electron-Positro Collision

17 Introduction and Motivation We have considered an effective Lagrangian method which provides a model independent way to understand beyond the SM effects, by encoding those in suitable parameters. WehaveconsideredfollowingprocessesatILCinourstudy- 1. Process 2. Process Following Feynman diagrams contributing to the process at tree level in the SM. 14/26

18 Results and Discussion Process 3 limit 15/26

19 Results and Discussion Single Parameter Analysis 3 limit 3 limit 16/26

20 Results and Discussion Correlation between and Two Parameter Analysis...,..,..,..,. 17/26

21 Results and Discussion Angular distribution 18/26

22 Results and Discussion Energy distribution 19/26

23 Results and Discussion Invariant mass distribution 20/26

24 Results and Discussion Process SM case 21/26

25 Results and Discussion Single Parameter Analysis 3 limit 3 limit 22/26

26 Results and Discussion Angular and invariant mass distribution 23/26

27 Results and Discussion Invariant mass and missing energy distribution 24/26

28 Summary and Conclusion The ILC with its clean environment and tunable initial state is better suited to perform precision measurements. We have considered an effective Lagrangian method which provides a model independent way to understand beyond the SM effects, by encoding those in suitable parameters. The selected processes of and productions are best suitedtostudythecoupling. Previous studies have obtained limits on this couplings assuming all other couplings to be standard. New physics effects in the Higgs sector can be probed through an effective Lagrangian in a model independent way. We have considered the limit obtainable on two of the effective coupling parameters, and at an ILC with for the production,and forthe production. 25/26

29 Summary and Conclusion singleparameterlimitwithanintegratedluminosityof give..and.. The above limits are considerably altered if new physics effect present in Higgs-gauge boson couplings. We also studied various kinematic distribution like cos, cos,,,. Where the sensitivity of and, and the influence of other parameters on this sensitivity are clearly demonstrated. Ourstudyhasclearlyillustratedthatprecisepriorknowledgeof, couplingsisnecessarytoeffectivelyprobethecoupling. One may need to rely on the knowledge of coupling from elsewhere, or can consider clever observables, in order to extract meaningful information regarding the triple Higgs coupling. Satendra Kumar and P. Poulose arxiv: v2 [hep-ph] 26/26

30 Thank you very much for your constant attention December 10, Science 2014 is a method for describing, creating and understanding of human experience :- R. Bruce Lindsay