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Asymmetry in flavour changing electromagnetic transitions of vector-like quarks.
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In this article, the decay rates and $CP$ asymmetry resulting from a combination of the imaginary components of the loop integrals and complex phases in the quark mixing matrix are analyzed.Abstract:
Vector-like quarks have been of interest for a plethora of experimentally motivated reasons and have come under increased investigation recently due to their inclusion to the Standard Model (SM) appreciably improving global fits to several flavour physics and precision electroweak measurements. The addition of vector-like quark singlets breaks the unitarity of the Cabibbo-Kobayashi-Maskawa (CKM) matrix and enables tree-level flavour changing neutral (FCN) vertices. The resulting radiative flavour changing decays of these particles through the electromagnetic transition dipole moment are a key means to study their properties and search for them at experiments like the Large Hadron Collider (LHC). Despite these radiative decays providing such a clean experimental signature, an explicit analytical study of the branching ratios and $CP$ violation resulting from these loop level processes has thus far evaded attention. We provide the formulation for the decay rates and $CP$ asymmetry resulting from a combination of the imaginary components of the loop integrals and complex phases in the quark mixing matrix. We then apply our analytical results to study phenomenology of these states for several global fits pertaining to vector-like isosinglets $t'$ and $b'$. We find that clean collider signatures and polarisation observables can be generated for both $t'$ and $b'$.read more
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TL;DR: In this article , the authors investigate all three representations of vector-like quarks under the Standard Model gauge group that can generate a sizable branching ratio for the rare flavor-changing top quark decay without violating bounds from $B$ physics.
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Searching for a vector-like B quark through a tW decay channel at future electron–positron colliders
Lin Han,Jie-Fen Shen,Yaobei Liu +2 more
TL;DR: In this paper , the SU (2) singlet vector-like bottom quark (VLQ-B ) was discovered in the decay channel of the 3 TeV Compact Linear Collider (CLIC).
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Search for pair production of the heavy vectorlike top partner in same-sign dilepton signature at the HL-LHC
TL;DR: In this paper , a simplified model including a singlet vector-like top partner with charge $2/3 was proposed to investigate the process of finding new vectorlike quarks at the high-luminosity LHC (HL-LHC).
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Global fit of modified quark couplings to EW gauge bosons and vector-like quarks in light of the Cabibbo angle anomaly
TL;DR: In this article , a combined analysis for all dimension-six Standard Model Effective Field Theory operators that generate modified $W$ couplings to first and second generation quarks is presented. But due to the SU(2)_L$ invariance, quarks are also modified and flavour changing neutral currents can occur.
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Do the small numbers in the quark mixing arise from new physics?
TL;DR: In this paper , it was shown that the small numbers in the $$V_\text {CKM}$$ matrix are generated by physics beyond the Standard Model, and the conjecture can be realized in the context of an up-type vector-like quark.
References
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Rare decays of the top quark in the standard and two-Higgs-doublet models.
TL;DR: The decays of heavy quarks are calculated, keeping all masses, in the standard model for all possible values of the top-quark mass that are consistent with present data and the possible contributions of charged Higgs bosons to the transitions are extended.