Changes between Version 2 and Version 3 of TFCNC
 Timestamp:
 01/06/14 11:55:51 (7 years ago)
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TFCNC
v2 v3 20 20 21 21 === Description === 22 This model is an extension of the Standard Model (SM), intended for the study of flavorchanging neutral Higgs interactions in the framework of general two Higgs doublet models [1]. As a generic framework, the following interactions are added to the SM Lagrangian [[Image(Lagrangian.png)]] where H is a generic CPeven scalar boson, and the real parameters K_utH and K_cTH denote the flavorchanging couplings of H to uptype quarks. The scenario K_utH = K_ctH = 0 corresponds to the SM case with H being the physical Higgs boson. We highlight that this parametrisation does not include the possiblity for offshell decays of the H boson, potentially allowing for large values of the associated decay rates due to threebody decays. The H boson default mass and width are set to 125 GeV and 5.75 MeV, respectively. Caution should be exercised when considering the decay width of the top quark, which value in the parameter cards should be adjusted depending on the values of the new flavorchanging couplings. The new userdefined parameters consist of the FCNC block, containing the new flavorchanging couplings of the Higgs boson and top quark to the up and charm quarks (set to 0 and 1, respectively).22 This model is an extension of the Standard Model (SM), intended for the study of flavorchanging neutral Higgs interactions in the framework of general two Higgs doublet models [1]. More general parametrizations can be found in the context of effective field theories [2]. As a generic framework, the following interactions are added to the SM Lagrangian [[Image(Lagrangian.png)]] where H is a generic CPeven scalar boson, and the real parameters K_utH and K_cTH denote the flavorchanging couplings of H to uptype quarks. The scenario K_utH = K_ctH = 0 corresponds to the SM case with H being the physical Higgs boson. We highlight that this parametrisation does not include the possiblity for offshell decays of the H boson, potentially allowing for large values of the associated decay rates due to threebody decays. The H boson default mass and width are set to 125 GeV and 5.75 MeV, respectively. Caution should be exercised when considering the decay width of the top quark, which value in the parameter cards should be adjusted depending on the values of the new flavorchanging couplings. The new userdefined parameters consist of the FCNC block, containing the new flavorchanging couplings of the Higgs boson and top quark to the up and charm quarks (set to 0 and 1, respectively). 23 23 24 24 === Files === 25 25 26 The model files have been validated analytically and numerically against the results presented in [arXiv:1112.1707] and [arXiv:1305.4172] for the top quark decay rates and the samesign top pair production crosssections, respectively. Below we provide the tarballs containing the main model files and outputs. The model implementation is also known to work with the CalcHEP/CompHEP interfaces, which can be generated from the TFCNC.nb Mathematica notebook. To import the model into MadGraph, it is enough to copy the UFO directory into the /models/ subdirectory of MadGraph, and load the model using the "import model TFCNC_UFO" command.26 The model files have been crosschecked analytically and numerically against the results presented in [1] and [3] for the top quark decay rates and the samesign top pair production crosssections, respectively. The UFO model was generated with FeynRules 2.0, and validation has been performed using MG5_aMC 2.0.0. Below we provide the tarballs containing the main input files. The model implementation is also known to work with the CalcHEP/CompHEP interfaces, which can be generated from the TFCNC.nb Mathematica notebook. To import the model into MadGraph, it is enough to copy the UFO directory into the /models/ subdirectory of MadGraph, and load the model using the "import model TFCNC_UFO" command. 27 27 28 28 * [attachment:TFCNC.fr] : FeynRules main file. … … 34 34 [1] C. Kao, H.Y. Cheng, W.S. Hou, J. Sayre, Top Decays with Flavor Changing Neutral Higgs Interactions at the LHC , Phys. Lett. B716 (2012) 225230 [arXiv:hepph/1112.1707]. 35 35 36 [2] M. Buchkremer, G. Cacciapaglia, A. Deandrea, L. Panizzi, Model Independent Framework for Searches of Top Partners, Nucl.Phys. B876 (2013) 376417 [arXiv:hepph/1305.4172].36 [2] C. Degrande, J.M. Gerard, C. Grojean, F. Maltoni, G. Servant, An effective approach to same sign top pair production at the LHC and the forwardbackward asymmetry at the Tevatron, Phys. Lett. B703 (2011) 306309 [arXiv:hepph/1104.1798]. 37 37 38 [3] C. Degrande, J.M. Gerard, C. Grojean, F. Maltoni, G. Servant, An effective approach to same sign top pair production at the LHC and the forwardbackward asymmetry at the Tevatron, Phys. Lett. B703 (2011) 306309 [arXiv:hepph/1104.1798].38 [3] M. Buchkremer, G. Cacciapaglia, A. Deandrea, L. Panizzi, Model Independent Framework for Searches of Top Partners, Nucl.Phys. B876 (2013) 376417 [arXiv:hepph/1305.4172].