Related papers: Model independent constraints on four-lepton opera…
In a bottom-up approach we investigate lepton-flavour violating processes $\tau \to 3 \ell$ that are mediated by New Physics encoded in effective-theory operators of dimension six. While the opportunity to scrutinize the underlying operator…
When the Standard Model is considered as an effective low-energy theory, higher dimensional interaction terms appear in the Lagrangian. Dimension-six terms have been enumerated in the classical article by Buchmueller and Wyler [3]. Although…
We predict the contribution of scalar unparticle to the branching ratios of the lepton flavor conserving Z -> l^+ l^- decays and we study the discrepancy between the experimental and the QED corrected standard model branching ratios. We…
This note presents a combination of published and preliminary electroweak results from the four LEP collaborations ALEPH, DELPHI, L3 and OPAL based on electron-positron collision data taken at centre-of-mass energies above the Z-pole, $130…
We explore constraints on the parameter space of the alternative left-right model originating from the leptonic sector. Our analyses focuses on both lepton-flavour-conserving observables, particularly the anomalous magnetic moment of the…
We explore the concept of effective alignments: contractions of multiple flavour symmetry breaking flavon fields. These contractions give rise to directions that are hard or impossible to obtain directly by breaking the flavour symmetry.…
We present a complete and independent list of the dimension 9 operator basis in the Standard Model effective field theory by an automatic algorithm based on the amplitude-operator correspondence. A complete basis (y-basis) is first…
We study the constraints that can be placed on anomalous $\tau$-lepton couplings at the LHC. We use an effective Lagrangian description for physics beyond the standard model which contains the $\tau$-lepton anomalous magnetic moment,…
The Standard Model Effective Field Theory (SMEFT) is a universal way of parametrizing New Physics (NP) manifesting as new, heavy particle interactions with the Standard Model (SM) degrees of freedom, that respect the SM gauged symmetries.…
We update the global constraint on four-fermion $ee q q$ contact interactions. In this update, we included the published data of H1 and ZEUS for the 94--96 run in the $e^+ p$ mode and the newly published data of H1 for the 1999 run in the…
We consider the hypothetical possibility of neutral gauge bosons~($Z^\prime$) with flavor-specific leptophilic couplings. For such {\it New Physics}~(NP) interactions, the current experimental constraints are much relaxed in the heavy mass…
We calculate $pp \to \ell^{+}\nu, \ell^-\bar \nu$ to ${\cal{O}}(1/\Lambda^4)$ within the Standard Model Effective Field Theory (SMEFT) framework. In particular, we calculate the four-fermion contribution from dimension six and eight…
Extensions of the standard model with low-energy supersymmetry generically allow baryon- and lepton-number violating operators of dimension four and five, yielding rapid proton decay. The dimension-four operators are usually forbidden by…
We investigate the consequences of introducing a set of exotic doublet leptons which couple to the standard model leptons in a minimal way. Through these additional gauge invariant and renormalizable coupling terms, new sources of…
We reassess non-standard triple gauge couplings in the light of the recent $(g-2)_\mu$ measurement at FNAL, the new lattice theory result of $(g-2)_\mu$ and the updated measurements of several $B$-decay modes. In the framework of SMEFT,…
A search for the neutrinoless, lepton-flavor violating decay of the tau lepton into three charged leptons has been performed using 376 fb^{-1} of data collected at an e^+e^- center-of-mass energy around 10.58 GeV with the BaBar detector at…
We have studied the correlations among the three absolute neutrino mass observables - the effective Majorana mass ($m_{ee}$) which can be obtained from neutrinoless double beta decay, the electron neutrino mass ($m_{\beta}$) which is…
We discuss the leptonic flavor structure generated by a brane shifted extra dimensional seesaw model with a single right handed neutrino in the bulk. In contrast to previous works, no unitarity approximation for the $3 \times 3$ submatrix…
The flavour lepton symmetry is gauged for both the Standard Model flavor group and its extension with three degenerate right-handed neutrinos. As a consequence of anomaly cancellation, exotic leptons are introduced which induce a see-saw…
Updated standard model predictions for $D_{(s)} \to P l^+ l^-$, $l=e,\mu$, $P=\pi,K$ and inclusive decays are presented. Model-independent constraints on $|\Delta C|=|\Delta U|=1$ Wilson coefficients are worked out. New physics (NP)…