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We study the effect of scalar leptoquarks in the lepton flavour violating $B$ meson decays induced by the flavour changing transitions $b \to q l_i^+ l_j^-$ with $q=s,d$. In the standard model these transitions are extremely rare as they…

High Energy Physics - Phenomenology · Physics 2016-06-08 Suchismita Sahoo , Rukmani Mohanta

In view of the emerging hints for the violation of lepton flavour universality in several $B$-meson decays, we conduct a model-independent study (effective field theory approach) of several well-motivated new physics scenarios. Taking into…

High Energy Physics - Phenomenology · Physics 2021-04-02 J. Kriewald , C. Hati , J. Orloff , A. M. Teixeira

We present a model based on $S_1$ scalar leptoquarks to solve the tension observed in the recently proposed non-leptonic optimized observables $L_{K^{*} \bar{K}^{*}}$ and $L_{K \bar{K}}$. These observables are constructed as ratios of…

High Energy Physics - Phenomenology · Physics 2023-09-20 Javier M. Lizana , Joaquim Matias , Ben A. Stefanek

We investigate the viability of extending the Standard Model with $S_1$ and $S_3$ scalar leptoquarks when the flavour structure is parametrized in terms of Froggatt-Nielsen charges. In contrast to a similar analysis with a vector…

High Energy Physics - Phenomenology · Physics 2021-03-17 Marzia Bordone , Oscar Cata , Thorsten Feldmann , Rusa Mandal

Leptoquarks have been suggested to solve a variety of discrepancies between the expected and observed phenomenon. In this paper, we investigate the effect of scalar leptoquarks on the lepton flavor violating B meson rare decays which…

High Energy Physics - Phenomenology · Physics 2019-01-10 Jin-Huan Sheng , Ru-Min Wang , Ya-Dong Yang

We consider lepton flavor violating Higgs decay, specifically $h \to \mu\tau$, in a leptoquark model. We introduce two scalar leptoquarks with the $SU(3)_c \times SU(2)_L \times U(1)_Y$ quantum numbers, $(3,2,7/6)$ and $(3,2,1/6)$, which do…

High Energy Physics - Phenomenology · Physics 2016-01-13 Seungwon Baek , Kenji Nishiwaki

Several experiments revealed intriguing hints for lepton flavor universality (LFU) violating new physics (NP) in semi-leptonic $B$ meson decays, mainly in $b \to c \tau \nu$ and $b \to s \ell^+ \ell^-$ transitions at the $3-5\,\sigma$…

High Energy Physics - Phenomenology · Physics 2019-06-05 Andreas Crivellin , Francesco Saturnino

$B$-physics data and flavor symmetries suggest that leptoquarks can have masses as low as few ${\cal{O}}(\mbox{TeV})$, predominantly decay to third generation quarks, and highlight $pp \to b \mu \mu$ signatures from single production and…

High Energy Physics - Phenomenology · Physics 2018-04-11 Gudrun Hiller , Dennis Loose , Ivan Nisandzic

Leptoquark models are prime candidates for new physics (NP) explanations of the long-standing anomalies in semi-leptonic $B$ decays; $b\to c \tau \bar\nu$ (encoded in $R(D^{(\ast)})$) and $b\to s\ell\bar\ell (\ell=e,\mu)$ transitions.…

High Energy Physics - Phenomenology · Physics 2025-11-24 Andreas Crivellin , Syuhei Iguro , Teppei Kitahara

Lepton number as a fourth color is an intriguing theoretical idea which is combined with a possible left-right symmetry within the famous Pati-Salam (PS) model. In the conventional PS model, a spontaneous breaking of the PS gauge group down…

High Energy Physics - Phenomenology · Physics 2018-12-12 Lorenzo Calibbi , Andreas Crivellin , Tianjun Li

Leptoquarks are prime candidates for explaining the intriguing hints for lepton flavour universality violation. In particular, the $SU(2)_L$ doublet of scalar leptoquarks $S_2$ is capable of providing an explanation for the tensions between…

High Energy Physics - Phenomenology · Physics 2022-07-05 Andreas Crivellin , Benjamin Fuks , Luc Schnell

We examine new aspects of leptoquark (LQ) phenomenology using effective field theory (EFT). We construct a complete set of leading effective operators involving SU(2) singlets scalar LQ and the SM fields up to dimension six. We show that,…

High Energy Physics - Phenomenology · Physics 2019-10-14 Shaouly Bar-Shalom , Jonathan Cohen , Amarjit Soni , Jose Wudka

Motivated by the recent experimental progress on the $B$-meson decay anomalies (in particular the angular observables in $B\to K^\ast\mu\mu$), we rely on a simplified-model approach to study the prospects of vector leptoquarks in what…

High Energy Physics - Phenomenology · Physics 2021-12-20 C. Hati , J. Kriewald , J. Orloff , A. M. Teixeira

There has been persistent disagreement between the Standard Model (SM) prediction and experimental measurements of $R_{D^{(*)}}=\mathcal{B}(\bar B \rightarrow D^{(*)} \tau \bar\nu_\tau)/\mathcal{B}(\bar B \rightarrow D^{(*)} l \bar\nu_l)$…

High Energy Physics - Phenomenology · Physics 2019-03-06 Saurabh Bansal , Rodolfo M. Capdevilla , Christopher Kolda

We extend the $SU(3)_C \times SU(3)_L \times U(1)_X$ model with neutral leptons (331LHN) by introducing scalar leptoquarks. We determine the particle content of the leptoquark multiplets and their Yukawa interactions with fermions. We find…

High Energy Physics - Phenomenology · Physics 2026-04-15 D. T. Binh , V. H. Binh , H. T. Hung , Duong Van Loi

The collection of a few anomalies in semileptonic $B$-decays, especially in $b\rightarrow c \tau \bar{\nu}$, invites to speculate about the emergence of some striking new phenomena, perhaps interpretable in terms of a weakly broken $U(2)^n$…

High Energy Physics - Phenomenology · Physics 2017-01-06 Riccardo Barbieri , Christopher W. Murphy , Fabrizio Senia

The long-standing anomaly in the anomalous magnetic moment of the muon indicates the presence of chirality violating new physics contributions. A possible solution involves scalar leptoquarks with left- and right-handed couplings to the top…

High Energy Physics - Phenomenology · Physics 2017-03-29 Estefania Coluccio Leskow , Andreas Crivellin , Giancarlo D'Ambrosio , Dario Müller

It has been shown that the anomalies observed in $\bar B\to D^{(\ast)}\tau\bar\nu_\tau$ and $\bar B\to \bar K\ell^+\ell^-$ decays can be resolved by adding a single scalar or vector leptoquark to the Standard Model, while constraints from…

High Energy Physics - Phenomenology · Physics 2017-03-08 Xin-Qiang Li , Ya-Dong Yang , Xin Zhang

We introduce two scalar leptoquarks, the SU$(2)_L$ isosinglet denoted $\phi\sim(\mathbf{3}, \mathbf{1}, -1/3)$ and the isotriplet $\varphi\sim(\mathbf{3}, \mathbf{3}, -1/3)$, to explain observed deviations from the standard model in…

High Energy Physics - Phenomenology · Physics 2019-10-17 Innes Bigaran , John Gargalionis , Raymond R. Volkas

Recently reported anomalies in various $B$ meson decays and also in the anomalous magnetic moment of muon $(g-2)_\mu$ motivate us to consider a particular extension of the standard model incorporating new interactions in lepton and quark…

High Energy Physics - Phenomenology · Physics 2023-01-18 Kayoung Ban , Yongsoo Jho , Youngjoon Kwon , Seong Chan Park , Seokhee Park , Po-Yan Tseng