Related papers: A Challenge to Lepton Universality in B Meson Deca…
Any theory that have a global spontaneously broken symmetry will imply the existence of very light neutral bosons or massless bosons (sometimes called Majorons). For most of these models we have neutrino-Majoron couplings, that appear as…
The mass of an electroweakly charged lepton consists of the two components of electric and weak nature, and regardless of the difference in masses, all leptons have an equal charge, the same charge radius as well as an identical magnetic…
The most recent measurements of the observables $R_{D^{(*)}}$ are in tension with the Standard Model offering hints of New Physics in $b\rightarrow c \ell \bar{\nu}_{\ell}$ transitions. Motivated by these results, in this work we present an…
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…
Motivated by renewed evidence for new physics in $b \to s\ell\ell$ transitions in the form of LHCb's new measurements of theoretically clean lepton-universality ratios and the purely leptonic $B_s\to\mu^+\mu^-$ decay, we quantify the…
The electroweak sector of the Standard Model contains three generations of charged leptons $\ell^-\in\{e^-,\mu^-,\tau^-\}$ as exact replicas of each other, except for their Yukawa couplings to the Higgs that determine their masses. The…
The possibility that the interactions of the third generation of quarks and leptons may violate universality by a small amount remains an open experimental question. The model of Li and Ma, which naturally accommodates such violations, is…
Several experiments observed deviations from the Standard Model (SM) in the flavour sector: LHCb found a $4-5\,\sigma$ discrepancy compared to the SM in $b\to s\mu^+\mu^-$ transitions (recently supported by an Belle analysis) and CMS…
The LHCb measurements of the $\mu / e$ ratio in $B \to K \ell \ell$ decays $(R_{K^{}})$ indicate a deficit with respect to the Standard Model prediction, supporting earlier hints of lepton universality violation observed in the…
Anomalies in (semi)leptonic $B$-meson decays present interesting patterns that might be revealing the shape of the new physics to come. In order to understand the experimental data, we explore symmetry arguments that lead to the hypothesis…
Precision data on Kl3 and Kl2 decay rates and form factors allow us to perform significant tests of lepton universality and to constrain the strength of non-standard interactions. The present status of these tests and new physics searches…
Recently Georgi has discussed the possible existence of `Unparticles' describable by operators having non-integral scaling dimensions. With the interaction of these with the Standard Model (SM) particles being constrained only by gauge and…
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…
Precise measurements of the lepton properties provide stringent tests of the Standard Model and accurate determinations of its parameters. We overview the present status of tau physics, highlighting the most recent developments, and discuss…
We confront the indications of lepton flavor universality (LFU) violation observed in semi-tauonic $B$ meson decays with new physics (NP) searches using high $p_T$ tau leptons at the LHC. Using effective field theory arguments we correlate…
The ratio of branching ratios of the $W$ boson to muons and electrons, $R^{\mu/e}_W=B(W\rightarrow \mu\nu)/B(W\rightarrow e\nu)$, has been measured using 140 fb$^{-1}$ of $pp$ collision data at $\sqrt{s}=13$ TeV collected with the ATLAS…
We test whether or not the tau lepton manifests the same couplings as the mu lepton by investigating the relative decay rates in purely leptonic D+ meson decays. Specifically, we place the first upper limit on the ratio R=Gamma(D+ -> tau+…
The kaon sector is characterised by several processes which are under active investigation across different experiments. In this work, we present the global picture that emerges from a study of the different decay modes. We begin by…
In recent years, exciting (indirect) hints for physics beyond the Standard Model (SM) have been accumulated. In particular, semi-leptonic $B$ decays show deviations from the SM predictions, which, due to the ratios $R(K^{(*)})$ and…
We consider the $\nu$MSM which is an extension of the Standard Model by three right-handed neutrinos with masses below the electroweak scale, in which the origins of neutrino masses, dark matter, and baryon asymmetry of the universe are…