Related papers: Tree-level new physics in $R(K^{(*)})$
Tests of lepton-universality as rate ratios in $b\to s \ell\ell$ transitions can be predicted very accurately in the Standard Model. The deficits with respect to expectations reported by the LHCb experiment in muon-to-electron ratios of the…
The hierarchy of scales which would allow dimension-six contact interactions to parametrise New Physics may not be verified at colliders. Instead, we explore the feasability and usefulness of parametrising the high-energy tail of…
Measuring the Higgs couplings accurately at colliders is one of the best routes for finding physics Beyond the Standard Model (BSM). If the measured couplings deviate from the SM predictions, then this would give rise to energy-growing…
We investigate a new class of improved relativistic fermion action on the lattice with a criterion to give excellent energy-momentum dispersion relation as well as to be consistent with tree-level $O\left(a^{2}\right)$-improvement. Main…
The B_s to mu+ mu- decay plays an outstanding role in tests of the Standard Model and physics beyond it. The LHCb collaboration has recently reported the first evidence for this decay at the 3.5 sigma level, with a branching ratio in the…
A method to extract B-physics parameters (b-quark mass and fB, fBs decay constants) from currently available lattice data is presented and tested. The approach is based on the idea of constructing appropriate ratios of heavy-light meson…
The implementation of the little Higgs mechanism to solve the hierarchy problem provides an interesting guiding principle to build particle physics models beyond the electroweak scale. Most model building works, however, pay not much…
In a scenario in which fourth generation fermions exist, we study effects of new physics on the differential decay width, forward-backward asymmetry $A_{\text{FB}}$ and integrated branching ratio for $B\to X_s \ell^+ \ell^-$ decay with…
Current experimental information on the charm meson decay observables in which the $c\to s\ell\nu_\ell$ transitions occur is well compatible with the Standard Model predictions. Recent precise lattice calculations of the $D_s$ meson decay…
We present updated global fits of the Standard Model and beyond to electroweak precision data, taking into account recent progress in theoretical calculations and experimental measurements. From the fits, we derive model-independent…
In this work, we update the constraints on tree level FCNC couplings in the framework of a theory with n isosinglet vector-like down quarks. In this context, we emphasize the sensitivity of the B -> J/psi K_S CP asymmetry to the presence of…
We analyze possible new physics (NP) effects on $b\to s$ transition processes, $R(K^{(*)})$, $B_s\to\mu^+\mu^-$, and $B^+\to K^+\nu{\bar\nu}$ decays. Though recent data for $R(K^{(*)})$ and ${\rm Br}(B_s\to\mu^+\mu^-)$ are compatible with…
We calculate the new physics contributions to the rare semileptonic decay $B \to X_s l^+ l^-$ $(l=e,\mu)$ induced by the charged-Higgs loop diagrams appeared in the top quark two-Higgs doublet model (T2HDM). Within the considered parameter…
The Standard Model of particle physics is assumed to be a low-energy effective theory with new physics theoretically motivated to be around TeV scale. The dissertation presents theories with new physics beyond the Standard Model at the TeV…
A comprehensive study of the impact of new-physics on different observables for $B_{s}\to \phi \ell^{+}\ell^{-}$ has been done. We examine the new physics models such as $Z^{\prime}$ and UED models, where the effects of new physics coming…
A range of flavour physics observables show tensions with their corresponding Standard Model expectations: measurements of leptonic flavour-changing neutral current processes and ratios of semi-leptonic branching fractions involving…
Motivated by the anomalies present in $b \to u$ and $b \to c$ semileptonic decays, we study the corresponding $B_s \to (K,K^*) \tau \nu$ and $B \to \pi \tau \nu$ decays within an effective field theory formalism. Our analysis is based on a…
The persisting anomalous data in semileptonic B-decays point towards New Physics models exhibiting large sources of Lepton Flavour Universality Violation. In this work we generalise previous studies by considering frameworks which include…
We report the first lattice QCD calculation of the form factors for the standard model tree-level decay $B_s\to K \ell\nu$. In combination with future measurement, this calculation will provide an alternative exclusive semileptonic…
In the scenario with Z mediated flavor changing neutral current occurring at the tree level due to the addition of a vector-like isosinglet down-type quark d' to the SM particle spectrum, we perform a chi square fit using the flavor physics…