Changes between Version 1 and Version 2 of GeorgiMachacekModel


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Timestamp:
11/07/14 19:48:52 (6 years ago)
Author:
kkumar84
Comment:

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  • GeorgiMachacekModel

    v1 v2  
    1 To be edited by Kunal...
     1Author Info
     2------------
     3Model Description and Implementation
     4
     5The Georgi-Machacek (GM) model was proposed in 1985 [G,M paper] as a plausible scenario for EWSB with interesting collider signatures. In this model, the scalar sector of the Standard Model (SM) is extended by the addition of one complex and one real SU(2) triplet. The hypercharge assignments of the triplets allows for a custodial SU(2) symmetry to be imposed upon the scalar potential, so that rho=1 is preserved at tree level. This is desirable for SM extensions in light of constraints from electroweak precision data. The model has the following salient features that make it phenomenologically interesting:
     6 -  the hVV (and hhVV) coupling can be enhanced compared to the SM
     7 -  the presence of additional scalars (including doubly charged ones)
     8The GM model can thus be a useful benchmark for the study of Higgs properties as well as searches for additional scalars.
     9
     10The doublet vev  v_phi and the triplet vevs v_chi are constrained by
     11v_phi^2 + 8 v_chi^2 = v_SM^2  to ensure the model generates the measured W and Z boson masses. We parametrize the relative size of the vevs by tan \theta_H = 2\sqrt{2} v_chi/v_phi.
     12
     13The scalars (apart form Goldstone bosons) in this model can be classified as two custodial SU(2) singlets, a triplet and a fiveplet. The two custodial singlets mix by an angle alpha to give eigenstates h and H, one of which is the 125 GeV Higgs.
     14
     15We follow Ref. [our paper] to implement the most general scalar potential that conserves custodial SU(2).  It is automatically CP-conserving. The parameters of the potential are denoted by
     16mu2sq, mu3sq, lam1, lam2, lam3, lam4, lam5, M1coeff and M2coeff in the .fr file. We trade three of these to obtain the set of 9 external parameters (mh, Gf, tanth, lam2, lam3, lam4, lam5, M1coeff, M2coeff) in the .fr file that define the scalar potential.
     17
     18The GM Lagrangian implementation is based on the SM implementation (SM. fr v 1.3).
     19In addition to the scalar potential, we modify all the relevant SM Lagrangian terms
     20that change in the GM model (e.g.: Scalar Kinetic Terms, Yukawa couplings).
     21
     22We also provide the CalcHEP and MG5 model folders generated from the .fr file.
     23In the case of MG5, event generation can be simplified by using the program GMCALC to generate
     24a param_card.dat file. (Note that the widths of t, W+, h and additional scalars should be updated in MG5 using the compute_widths option.)
     25
     26
     27References
     281. GM
     292. ourpaper
     30------------
     31
     32Model files
     33------------
     34GMCALC link
     35------------
     36Additional Files
     37   UFO folder and CalcHEP folder
     38------------