Changes between Version 25 and Version 26 of VLQ


Ignore:
Timestamp:
04/21/14 12:11:35 (5 years ago)
Author:
buchkremer
Comment:

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  • VLQ

    v25 v26  
    5757In order to provide an exhaustive test of all the top partners couplings, the cross-sections for a selection of processes of direct phenomenological interest for the model applications have been tested systematically. The detailed simulation of the signals has been performed using Madgraph5 (Version: 1.5.7) for event generation at the partonic level, interfaced with PYTHIA (Version: 2.1.20) for parton showering. The QCD pair-production cross-sections have been computed in the VLQ model and match the leading order predictions at the % level for top pair production when setting M = mt at 7, 8 and 14 TeV LHC running energies.
    5858
    59 As for electroweak production, the t-channel, s-channel and WT associated production cross-sections have been compared to the results in [3] for unity mixings (|Vtb|²=1), and are consistent with the SM predictions for M equal to the top mass. All the simulations have been performed independently in CalcHep, MadGraph4 (Usermod) and MadGraph5 (FeynRules) for various benchmark points (M = 600,800 and 1000 GeV) at leading order (CTEQ6L1). The cross-sections for Vector-Like quarks and anti-quarks have been compared for pp > Qt, Qj, QW, QZ and QH between the three built-in implementations, and the results are in agreement at the % level, except for pp > Qj which may allow for deviations as large as 10% in the W- and Z- mediated channels. Finally, the model results have been compared to the cross-sections presented in [6], assuming exclusive mixing with the first generation for all four Vector-Like quark types. The ratios of the cross-sections for electroweak single production of X, T, B and Y quarks have been compared with MadGraph for M = 900 (1800) GeV
     59As for electroweak production, the t-channel, s-channel and WT associated production cross-sections have been compared to the results in [3] for unity mixings (|Vtb|²=1), and are consistent with the SM predictions for M equal to the top mass. All the simulations have been performed independently in CalcHep, MadGraph4 (Usermod) and MadGraph5 (FeynRules) for various benchmark points (M = 600,800 and 1000 GeV) at leading order (CTEQ6L1). The cross-sections for Vector-Like quarks and anti-quarks have been compared for pp > Qt, Qj, QW, QZ and QH between the three built-in implementations, and the results are in agreement at the % level, except for pp > Qj which may allow for deviations as large as 10% in the W- and Z- mediated channels. Please note that the use of the MadGraph implementation is here restricted to 2>2 processes. Finally, the model results have been compared to the cross-sections presented in [6], assuming exclusive mixing with the first generation for all four Vector-Like quark types. The ratios of the cross-sections for electroweak single production of X, T, B and Y quarks have been compared with MadGraph for M = 900 (1800) GeV
    6060at the LHC for 7(14) TeV, N=50000 events and MZ-fixed factorization and renormalization scales (CTEQ6L1). The results are found to be consistent at the 5% level.
    6161