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At the back of succeeding measurements of anomalies in semileptonic decays at LHCb and several collider experiments hinting at the possible violation of lepton flavor universality, we undertake a concise review of theoretical foundations of…

High Energy Physics - Phenomenology · Physics 2023-03-14 Sonali Patnaik , Rajeev Singh

The LHCb measurements on the B ->$ K^*$$\mu^+ \mu^-$ angular observables have shown slight deviations from their Standard Model predictions. The significance of the deviations in the B -> $K^*$$\mu^+ \mu^-$ decay depends on the assumptions…

High Energy Physics - Phenomenology · Physics 2017-05-31 S. Neshatpour , V. G. Chobanova , T. Hurth , F. Mahmoudi , D. Martinez Santos

In the Standard Model (SM), the rare transitions where a bottom quark decays into a strange quark and a pair of light leptons exhibit a potential sensitivity to physics beyond the SM. In addition, the SM embeds Lepton Flavour Universality…

High Energy Physics - Phenomenology · Physics 2018-02-14 Bernat Capdevila , Andreas Crivellin , Sébastien Descotes-Genon , Joaquim Matias , Javier Virto

Rare semileptonic $b \to s \ell^+ \ell^-$ transitions provide some of the most promising frameworks to search for new physics effects. Recent analyses of these decays have indicated an anomalous behaviour in measurements of angular…

High Energy Physics - Phenomenology · Physics 2019-03-21 Andrea Mauri , Nicola Serra , Rafael Silva Coutinho

We perform a general model-independent analysis of $b \to c \tau \bar{\nu}_\tau $ transitions, including measurements of $\mathcal{R}_D$, $\mathcal{R}_{D^*}$, their $q^2$ differential distributions, the recently measured longitudinal $D^*$…

High Energy Physics - Phenomenology · Physics 2019-10-10 Clara Murgui , Ana Peñuelas , Martin Jung , Antonio Pich

The Standard Model predicts that the electroweak couplings to the three charged leptons are identical. However, in the last decade, experimental measurements have suggested that semileptonic processes involving taus could have a slightly…

High Energy Physics - Experiment · Physics 2024-10-24 Rizwaan Mohammed

The LHCb collaboration has very recently released a new study of $B^+ \to K^{+} \ell^+ \ell^-$ and $B \to K^{*0} \ell^+ \ell^-$ ($\ell = e,\mu$) decays, testing lepton universality with unprecedented accuracy using the whole Run 1 and 2…

High Energy Physics - Phenomenology · Physics 2023-04-05 Marco Ciuchini , Marco Fedele , Enrico Franco , Ayan Paul , Luca Silvestrini , Mauro Valli

In this letter we propose a strategy for discerning if new physics in the Wilson coefficient ${\cal C}_{9\mu}$ is dominantly lepton flavour universality violating or if it contains a sizable lepton flavour universal component (${\cal…

High Energy Physics - Phenomenology · Physics 2022-07-15 Marcel Algueró , Bernat Capdevila , Andreas Crivellin , Joaquim Matias

We study the implications of the recent measurements of $R_K$ and $R_{K^*}$ by the LHCb collaboration. We do that by adopting a model-independent approach based on the Standard Model Effective Field Theory (SMEFT), in which the dominant new…

High Energy Physics - Phenomenology · Physics 2017-08-30 Alejandro Celis , Javier Fuentes-Martin , Avelino Vicente , Javier Virto

New results in processes with an underlying quark transition $b\to s \ell^+\ell^-$ have been recently reported by the LHCb and Belle II collaborations. In this note we show how the main implications of a handful of new measurements can be…

High Energy Physics - Phenomenology · Physics 2019-08-12 Bernat Capdevila , Ursula Laa , German Valencia

We present a global likelihood function in the space of dimension-six Wilson coefficients in the Standard Model Effective Field Theory (SMEFT). The likelihood includes contributions from flavour-changing neutral current B decays, lepton…

High Energy Physics - Phenomenology · Physics 2019-07-24 Jason Aebischer , Jacky Kumar , Peter Stangl , David M. Straub

We present constraints on Wilson coefficients from a combined fit to data from top-quark and beauty-physics measurements within the Standard Model effective field theory. We consider present data on top-quark pair production and decay,…

High Energy Physics - Phenomenology · Physics 2021-05-13 Stefan Bißmann , Cornelius Grunwald , Gudrun Hiller , Kevin Kröninger

We present a Bayesian analysis of the implications for new physics in semileptonic $b\to s$ transitions after including new measurements of $R_K$ at LHCb and new determinations of $R_{K^*}$ and $R_{K^{*+}}$ at Belle. We perform global fits…

High Energy Physics - Phenomenology · Physics 2019-10-15 Kamila Kowalska , Dinesh Kumar , Enrico Maria Sessolo

Disentangling New Physics effects from the Standard Model requires a good understanding of all pieces that stem from the latter, especially the uncertainties that might plague the theoretical estimations within the Standard Model. In the…

High Energy Physics - Phenomenology · Physics 2016-11-16 Marco Ciuchini , Marco Fedele , Enrico Franco , Satoshi Mishima , Ayan Paul , Luca Silvestrini , Mauro Valli

Even though the LHC searches did not unveil the new physics particles so far, LHCb hints towards deviations from lepton flavor universality in exclusive decays based on the transition $b\to s\ell\ell$. In this proceeding, we present a new…

High Energy Physics - Phenomenology · Physics 2017-10-25 Olcyr Sumensari

Semileptonic charged current $b \to c l^- \overline{\nu}_l$ decays offer a compelling avenue to probe the limits of the Standard Model and investigate lepton flavor universality (LFU). While the SM maintains flavor universality, new physics…

High Energy Physics - Experiment · Physics 2023-05-16 Abhijit Mathad

The LHCb collaboration has recently presented their result on R_K = BR(B+ -> K+ mu+ mu-)/ BR(B+ -> K+ e+ e-) for the dilepton invariant mass bin m_{ll}^2 = 1-6 GeV^2 (l = mu, e). The measurement shows an intriguing 2.6 sigma deviation from…

High Energy Physics - Phenomenology · Physics 2015-06-22 Diptimoy Ghosh , Marco Nardecchia , S. A. Renner

In the Standard Model and many of its extensions, it is well known that all of the observables associated with the rare decays $b\to s\gamma$ and $b\to s\ell^+\ell^-$ can be expressed in terms of the three Wilson coefficients,…

High Energy Physics - Phenomenology · Physics 2014-11-17 Thomas G. Rizzo

In view of both the latest LHCb measurement of $R_{K^{(*)}}$ and the new $2.8\sigma$ deviation reported by Belle II on $B^{+}\to K^{+}\nu\bar{\nu}$ decays, we present a fit to the $B$ meson anomalies for various one and two dimensional…

High Energy Physics - Phenomenology · Physics 2024-02-19 Peter Athron , R. Martinez , Cristian Sierra

LHCb found hints for physics beyond the standard model in $B\to K^*\mu^+\mu^-$, $B\to K^*\mu^+\mu^-/B\to K^*e^+e^-$ and $B_s\to\phi\mu^+\mu^-$. In addition, the BABAR results for $B\to D^{(*)}\tau\nu$ and the CMS excess in…

High Energy Physics - Phenomenology · Physics 2016-04-20 Andreas Crivellin