OPUCEM: A library with error checking mechanism for computing oblique parameters

Çobanoğlu, Ö.; Özcan, Erkcan; Sultansoy, S.; Ünel, G.

doi:10.1016/j.cpc.2011.04.018

Cited by 11 publications

(7 citation statements)

References 34 publications

(36 reference statements)

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“…Although the off-diagonal lepton mixings are required to be smaller than 0.115 to be consistent with the recent global fits [20], a trivial 4 × 4 PMNS unitary matrix is considered throughout this analysis, namely a long-lived Dirac neutrino with |U ν τ | = 1. We mention, however, the interest of the Majorana case, as the exhaustive study [21] has shown.…”

Section: Direct Limitsmentioning

confidence: 95%

Closing in on a perturbative fourth generation

Buchkremer

Gérard

Maltoni

2012

J. High Energ. Phys.

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A perturbative new family of fermions is now severely constrained, though not excluded yet. We reconsider the current bounds (i.e., direct and from Higgs searches, R_b, oblique parameters) on the fourth generation parameter space assuming the case of a small CKM mixing with the third generation. We identify viable scenarios featuring either a light or a heavy Higgs boson. A set of representative benchmark points targeted for LHC searches is proposed with a normal (inverted) quark mass hierarchy where t' -> b'W (b' -> tW) decays are sizable. In the case where the fourth generation couplings to the lighter quark families are small, we suggest that search strategies at the LHC should include both pair (strong) and single (weak) production with bb+nW (n=2,...,6) final state signatures.Comment: 23 pages, 6 figures, v2: some issues clarified and references added. To appear in JHE

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Section: Direct Limitsmentioning

confidence: 95%

Closing in on a perturbative fourth generation

Buchkremer

Gérard

Maltoni

2012

J. High Energ. Phys.

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“…These S, T, U parameters can be defined in both unphysical and physical gauge boson basis as [66,70,221,222]:…”

Section: Oblique Parametersmentioning

confidence: 99%

Hilbert series and plethystics: paving the path towards 2HDM- and MLRSM-EFT

Anisha

Bakshi

Chakrabortty

et al. 2019

J. High Energ. Phys.

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Effective Field Theory (EFT) technique is one of the most elegant ways to capture the impact of high scale theory, if any, at some low energy by incorporating higher mass dimensional (≥ 5) effective operators (O i ). The low energy EFT is described in terms of only light degrees of freedom (DOF) which can appear on-shell. An essential task while developing the EFT framework is to compute these O i 's. Hilbert Series (HS) is a novel and mathematically robust method to construct the complete set of gauge invariant independent, effective operators. The HS requires the knowledge of the transformation properties of the light DOF and the covariant derivatives under the internal gauge symmetries and conformal groups. The Hilbert Series method, by its virtue, automatically takes care of the redundancies in the operator set due to the Equations of Motion (EOMs) of fields and Integration by Parts (IBPs) with impeccable accuracy.In this paper, we have adopted this methodology to construct the complete set of independent operators up to dimension-6 in the "Warsaw"-like basis for two different Beyond Standard Model scenarios -Two Higgs Doublet Model (2HDM) and Minimal Left-Right Symmetric Model (MLRSM). For both these cases, we have calculated the corrections to the scalar, gauge boson and fermion mass spectra due to the dimension-6 operators. The additional contributions to all the Feynman vertices are computed and their impact on different observables, namely Weak mixing angle, Fermi constant, ρ and oblique (S, T, U ) parameters. We have further discussed how the magnetic moments of charged leptons and production and decay of the massive BSM particles, e.g., charged scalar and different rare processes are affected in the presence of effective operators. We have also constructed the effective scalar four-point interactions and commented on the possible reinvestigation of the theoretical constraints, e.g., unitarity and vacuum stability within these frameworks.

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“…The existence of the fourth SM family is the outcome of the flavor democracy hypothesis and the actual spectrum of the third family fermion masses [4][5][6] (see, also review [7] and ref's therein). Twenty years' ongoing discussions on "precision data vs fourth SM family" have been concluded in favor of the fourth SM family (see [8,9] and ref's therein). Today, the mass and the mixing patterns of quarks and leptons are the most mysterious aspects of particle physics.…”

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confidence: 99%

Searching for the fourth family quarks through anomalous decays

2010

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The existence of fourth family follows from the basics of the Standard Model. Because of the high masses of the fourth family quarks, their anomalous decays could be dominant, if certain criteria are met. This will drastically change the search strategy at hadron colliders. We show that the fourth SM family down quarks with masses up to 400 − 450 GeV can be observed (or excluded) via anomalous decays by Tevatron before the LHC.

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OPUCEM: A library with error checking mechanism for computing oblique parameters

Cited by 11 publications

References 34 publications

Closing in on a perturbative fourth generation

Closing in on a perturbative fourth generation

Hilbert series and plethystics: paving the path towards 2HDM- and MLRSM-EFT

Searching for the fourth family quarks through anomalous decays

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