Probing low energy scalar leptoquarks by the leptonic $W$ and $Z$ couplings

Abstract

We compute the generic one-loop contribution involving scalar leptoquarks (LQ) to the $W$ and $Z$ leptonic decay widths. In our computation we include for the first time the finite terms and the corrections due to the external momenta of the electroweak bosons, which is a step beyond the leading-logarithmic approximation considered in the literature so far. We show that the terms we include can be numerically quite significant. They amount to about $20\%$ for scalar LQ masses below $1.5$~TeV, as currently allowed by the direct searches at the LHC. To further illustrate the relevance of our results we revisit a model with two light scalar LQs, proposed to accommodate the $B$-physics anomalies. We show that the finite terms we computed can reduce the tension with the $Z$-pole data.

Minor typos amended

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Cited by in corpus (8)

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• Impact of $B\to K\nu \bar{\nu }$ measurements on beyond the Standard Model theories
• Unified SU(4) theory for the $R_{D^{(\ast )}}$ and $R_{K^{(\ast )}}$ anomalies
• Phenomenology of $b\to c\tau \bar{\nu }$ decays in a scalar leptoquark model
• Explaining anomalies of $B$-physics, muon $g-2$ and $W$ mass in $R$-parity violating MSSM with seesaw mechanism
• Constraining New Physics with Single Top production at LHC
• Perturbative unitarity constraints on generic Yukawa interactions
• Explaining lepton-flavor non-universality and self-interacting dark matter with $L_{\mu }-L_{\tau }$