Footprints of leptoquarks: from to

S. Fajfer; N. Košnik; L. Vale Silva

doi:10.1140/epjc/s10052-018-5757-5

EPJ

a
b
c
d
e
ap
st
h
plus
ds
pv
ti
qt
am
n

2023 Impact factor 4.2

Particles and Fields

Open Access

Eur. Phys. J. C (2018) 78: 275
https://doi.org/10.1140/epjc/s10052-018-5757-5

Regular Article - Theoretical Physics

Footprints of leptoquarks: from $R_{K^{(*)}}$ to $K \rightarrow \pi \nu \bar{\nu }$

S. Fajfer¹^,2, N. Košnik¹^,2 and L. Vale Silva³^*

¹ Jožef Stefan Institute, Jamova 39, 3000, 1001, Ljubljana, Slovenia
² Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000, Ljubljana, Slovenia
³ Department of Physics and Astronomy, University of Sussex, Falmer, Brighton, BN1 9QH, UK

^* e-mail: luiz.vale@th.u-psud.fr

Received: 9 February 2018
Accepted: 22 March 2018
Published online: 30 March 2018

Abstract

Rare $K \rightarrow \pi \nu \bar{\nu }$ decays, being dominated by short distance contributions within the standard model (SM), open a window for new physics (NP) searches at low energies. The $K \rightarrow \pi \nu \bar{\nu }$ branching ratios are expected to be measured with $\sim 10\%$ accuracies by NA62/CERN and KOTO/JPARC. The theoretical uncertainties of branching ratios within the SM are well under control. In the B sector, it is tentative to explain the B-meson anomalies $R_{D^{(*)}}$ and/or $R_{K^{(*)}}$ by effects of physics beyond the SM. Although NP seems to be present in the third fermion generation it might also manifest in the flavor changing neutral current transition $s \rightarrow d$ . Together with the anticipated good experimental sensitivities and accurate theoretical predictions for $K\rightarrow \pi \nu \bar{\nu }$ , this motivates studies of correlated effects of NP in rare $K\rightarrow \pi \nu \bar{\nu }$ and $B \rightarrow K^{(*)} \mu ^+ \mu ^-$ decays. Here we consider the loop induced effects in $K \rightarrow \pi \nu \bar{\nu }$ in two leptoquark models designed to address lepton-flavor universality violation in the $R_{K^{(*)}}$ anomalies.