Related papers: Lepton Flavor Universality tests in $b\to s\ell^+\…

The coupling of the electroweak gauge bosons of the Standard Model (SM) to leptons is flavour universal. Extensions of the SM do not necessarily have this property. Rare decays of heavy flavour are suppressed in the SM and new particles may…

Lepton universality, meaning the equal coupling of the electroweak gauge bosons to the different lepton flavours, is a central property of the Standard Model (SM). Tests of lepton universality in ratios of rates of $b\to s\ell^+\ell^-$…

In the Standard Model (SM), the coupling of the electroweak gauge bosons to the leptons is lepton flavour universal. Tests of this property constitute sensitive probes for new physics models that violate lepton flavour universality. Recent…

The Standard Model of particle physics predicts that charged leptons have the same electroweak interaction strength. This symmetry, called lepton flavour universality, was found to hold in a wide range of particle decays. One observable…

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…

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…

In the Standard Model, the three charged lepton are identical copies of each other, apart from mass differences. Experimental tests of this feature in decays of semileptonic b hadrons, such as $B\rightarrow D^* \tau\ nu$, are highly…

The Standard Model (SM) of particle physics represents our most fundamental knowledge of elementary particles and their interactions. One of the cardinal properties of the SM which has been thoroughly studied during the past years is the…

The first test of lepton flavor universality between muons and electrons using $B^+ \to K^+\pi^+\pi^-\ell^+\ell^-$ ($\ell=e,\mu$) decays is presented. The measurement is performed with data from proton-proton collisions collected by the…

This article discusses tests of lepton flavour universality that are carried out with the LHCb experiment. The experimental situation of \btosll and $b \to c \ell \nu$ decays is summarised.

In the Standard Model of particle physics, charged leptons of different flavour couple to the electroweak force carriers with the same interaction strength. This property, known as lepton flavour universality, was found to be consistent…

Lepton flavour universality in rare $b\rightarrow s$ transitions is tested for the first time using $B_s^0$ meson decays. The measurements are performed using $pp$ collision data collected by the LHCb experiment between 2011 and 2018,…

Tests of lepton flavour universality in charged-current $B$ decays offer an excellent opportunity to test the Standard Model, and show hints of new physics in analyses performed by the LHCb, Belle and BaBar experiments. These proceedings…

The basic features of quark and lepton mass matrices can be successfully explained by natural minima of a generic potential with dynamical Yukawa fields invariant under the $[\mathrm{SU(3)}]^5\times \mathcal{O}(3)$ flavor symmetry. If this…

The electroweak penguin B decays mediated by $b \to s \ell^+ \ell^- $ transitions are flavour-changing neutral current processes, and are thus sensitive to new physics owing to potential contributions of heavy particles in the quantum loop.…

The LHCb experiment at the Large Hadron Collider specialises in high-precision measurements of flavour physics with hadrons containing $b$ and $c$ quarks. Lepton flavour universality tests provide an accurate and clear approach to…

Flavour-changing neutral-current processes, such as $b\to s \ell^+\ell^-$, are forbidden at tree level in the Standard Model and hence might receive comparatively large corrections from new particles. This document highlights recent…

We study the flavor universality of the lepton couplings with the W and Z bosons. Currently, it is constrained by the electroweak precision observables. We focus on the leptonic decay of the pion. It is shown that the decay is expected to…

One of the fundamental predictions of the Standard Model is Lepton Flavour Universality. Any deviation from this prediction would indicate the existence of physics beyond the Standard Model. Recent LHCb measurements present a pattern of…

The first simultaneous test of muon-electron universality using $B^{+}\rightarrow K^{+}\ell^{+}\ell^{-}$ and $B^{0}\rightarrow K^{*0}\ell^{+}\ell^{-}$ decays is performed, in two ranges of the dilepton invariant-mass squared, $q^{2}$. The…