CP-violating dipole form factors of the top quark and tau lepton in scalar leptoquark models

Poulose, Poulose; Rindani, Saurabh D.

doi:10.1007/bf02828932

Cited by 10 publications

(7 citation statements)

References 34 publications

(26 reference statements)

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“…Scalar leptoquarks are predicted in a variety of particle physics models [73][74][75][76][77]. They contribute to the muon anomalous magnetic moment through the diagrams shown in Figs.1(a) and 1(b).…”

Section: Scalar Leptoquarksmentioning

confidence: 99%

New physics contributions to the muon anomalous magnetic moment: A numerical code

2014

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We consider the contributions of individual new particles to the anomalous magnetic moment of the muon, utilizing the generic framework of simplified models. We also present analytic results for all possible one-loop contributions, allowing easy application of these results for more complete models which predict more than one particle capable of correcting the muon magnetic moment. Additionally, we provide a Mathematica code to allow the reader straightforwardly compute any 1-loop contribution. Furthermore, we derive bounds on each new particle considered, assuming either the absence of other significant contributions to a µ or that the anomaly has been resolved by some other mechanism. The simplified models we consider are constructed without the requirement of SU (2) L invariance, but appropriate chiral coupling choices are also considered. In summary, we found the following particles capable of explaining the current discrepancy, assuming unit couplings: 2 TeV (0.3 TeV) neutral scalar with pure scalar (chiral) couplings, 4 TeV doubly charged scalar with pure pseudoscalar coupling, 0.3 − 1 TeV neutral vector boson depending on what couplings are used (vector, axial, or mixed), 0.5−1 TeV singly-charged vector boson depending on which couplings are chosen, and 3 TeV doubly-charged vector-coupled bosons. We also derive the following 1σ lower bounds on new particle masses assuming unit couplings and that the experimental anomaly has been otherwise resolved: a doubly charged pseudo-scalar must be heavier than 7 TeV, a neutral scalar than 3 TeV, a vector-coupled new neutral boson 600 GeV, an axial-coupled neutral boson 1.5 TeV, a singly-charged vector-coupled W 1 TeV, a doubly-charged vector-coupled boson 5 TeV, scalar leptoquarks 10 TeV, and vector leptoquarks 10 TeV. We emphasize that the quoted numbers apply within simplified models, but the reader can easily use our Mathemata code to calculate the contribution of their own model of new physics.

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Section: Scalar Leptoquarksmentioning

confidence: 99%

New physics contributions to the muon anomalous magnetic moment: A numerical code

2014

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“…[22], and calculate the corresponding contribution to the WMDM and the WEDM of a fermion. Although the WEDM of heavy fermions has already been studied in the context of leptoquark models [32,33], to our knowledge there is no previous analysis on the behavior of the contributions of leptoquarks to the WMDM. In the model I of Ref.…”

Section: Weak Dipole Moments Of a Fermion In Scalar Leptoquark Momentioning

confidence: 99%

Static weak dipole moments of theτlepton via renormalizable scalar leptoquark interactions

2014

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The weak dipole moments of elementary fermions are calculated at the one-loop level in the framework of a renormalizable scalar leptoquark model that forbids baryon number violating processes and so is free from the strong constraints from experimental data. In this model there are two scalar leptoquarks accommodated in an SUL(2) × UY (1) doublet: one of such leptoquarks is non-chiral and has electric charge of 5/3e, whereas the other one is chiral and has electric charge 2/3e. In particular, a non-chiral leptoquark contributes to the weak properties of an up fermion via a chirality flipping-term proportional to the mass of the virtual fermion and can also induce a non-zero weak electric dipole moment provided that the leptoquark couplings are complex. The numerical analysis is focused on the weak properties of the τ lepton since they offer good prospects for their experimental study. The constraints on leptoquark couplings are briefly discussed for a non-chiral leptoquark with non-diagonal couplings to the second and third fermion generations, a third-generation non-chiral leptoquark, and a third-generation chiral leptoquark. It is found that although the chirality-flipping term can enhance the weak properties of the τ lepton via the top quark contribution, such an enhancement would be offset by the strong constraints on the leptoquark couplings. So, the contribution of scalar leptoquarks to the weak magnetic dipole moment of the τ lepton are smaller than the standard model (SM) contributions but can be of similar size than those arising in some SM extensions. A non-chiral leptoquark can also give contributions to the weak electric dipole moment larger than the SM one but well below the experimental limit. We also discuss the case of the off-shell weak dipole moments and for completeness analyze the behavior of the τ electromagnetic properties. * Email: gtv@fcfm.buap.mx 2

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“…We have evaluated these Passarino-Veltman functions numerically using existing numerical packages [14]. An alternative method involves calculation of the absorptive parts explicitly in terms of simple integrals and then reexpressing the real parts in terms of dispersion relations [15]. We have checked that the two methods give identical results.…”

Section: The Zzz Vertexmentioning

confidence: 99%

“…For the real parts, the situation is analogous, but slightly more complex. This part can be better in terms of a dispersion integral of the absorptive part [15]. The opening up of a channel now manifests itself as a kink, rather than a typical threshold jump.…”

Section: The Sm Contribution Revisitedmentioning

confidence: 99%

Trilinear Neutral Gauge Boson Couplings

Choudhury

Dutta

Rakshit

et al. 2001

Int. J. Mod. Phys. A

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CP-violating dipole form factors of the top quark and tau lepton in scalar leptoquark models

Cited by 10 publications

References 34 publications

New physics contributions to the muon anomalous magnetic moment: A numerical code

New physics contributions to the muon anomalous magnetic moment: A numerical code

Static weak dipole moments of theτlepton via renormalizable scalar leptoquark interactions

Trilinear Neutral Gauge Boson Couplings

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