Related papers: First bounds on effective muon interactions using …

We derive bounds on couplings in the standard model effective field theory (SMEFT) as a consequence of causality and the analytic structure of scattering amplitudes. In the SMEFT, there are 64 independent operators at mass dimension eight…

We investigate the prospects for detecting light leptophilic dark sectors with a missing-momentum experiment at NA64 running in muon mode. In particular, we consider models in which dark matter connects to the visible sector through a…

We investigate flavour violating four Fermi Standard Model Effective Field Theory (SMEFT) operators of dimension-six that can be probed via $tc ~(\bar{t}c+t\bar{c})$ production at the multi-TeV muon collider. We study different FCNC and…

We consider the anomalous magnetic moment of the muon $a_\mu$, which shows a significant deviation from the Standard Model expectation given the recent measurements at Fermilab and BNL. We focus on Standard Model Effective Field Theory…

We consider higher-dimensional effective (EFT) operators consisting of fermion dark matter (DM) connecting to Standard Model (SM) leptons upto dimension six. Considering all operators together and assuming the DM to undergo thermal…

The $4.2\sigma$ discrepancy in the $(g-2)$ of the muon provides a hint that may indicate that physics beyond the standard model is at play. A multi-TeV scale muon collider provides a natural testing ground for this physics. In this paper,…

It is not only conceivable but likely that the spectrum of physics beyond the Standard Model (SM) is non-degenerate. The lightest non-SM particle may reside close enough to the electroweak scale that it can be kinematically probed at…

The Standard Model Effective Field Theory (SMEFT) based on the unbroken gauge group $\text{SU(3)}_C\otimes\text{SU(2)}_L\otimes\text{U(1)}_Y$ and containing only particles of the Standard Model (SM) has developed in the last decade to a…

Even if some experimental evidence suggests the existence of physics beyond the SM, no clues of new resonances can be found in the data. In the case their masses are much larger than the energies of current experiments, the SMEFT formalism…

We generalize in several directions our recent analysis of the limitations to the use of the effective field theory approach to study dark matter at the LHC. Firstly, we study the full list of operators connecting fermion DM to quarks and…

The NA64 electron beam program comprises of a high sensitivity search for visible and invisible decays of the hypothetical dark photon, $A'$, with a goal to either observe the sub-GeV Dark Matter mediator or exclude most of the model…

In the absence of a concrete discovery of new physics at the LHC, global analyses of the standard model effective field theory (SMEFT) are important to find and describe the impact of new physics beyond the energy reach of the LHC. Among…

The inclusion of an additional $U(1)$ gauge $L_\mu-L_\tau$ symmetry would release the tension between the measured and the predicted value of the anomalous muon magnetic moment: this paradigm assumes the existence of a new, light $Z^\prime$…

Charged lepton-flavor violation is a null-test frontier of the Standard Model and a direct probe of physics beyond it. We present a global effective field theory (EFT) analysis across FCC-ee, ILC, CLIC, HL-LHC, HE-LHC, and muon colliders at…

An Effective Field Theory (EFT) analysis of the magnetic moment of the muon is discussed. The expression for the dipole moment is given in terms of operator coefficients of the low-energy effective field theory (LEFT) and the Standard Model…

We report on a search for a new $Z'$ ($L_\mu-L_\tau$) vector boson performed at the NA64 experiment employing a high energy muon beam and a missing energy-momentum technique. Muons from the M2 beamline at the CERN Super Proton Synchrotron…

In this study, we demonstrate the potential of the NA64 experiment at CERN SPS to search for New Physics processes involving $e\rightarrow\mu$ transitions after the collision of 100 GeV electrons with target nuclei. A new Dark Sector…

The impact of new physics on the interactions of neutrinos with other particles can be parametrized by a set of effective four-fermion operators called non-standard neutrino interactions (NSIs). This NSI framework is useful for studying the…

This is a sequel to our recent work [1] in which we calculated the lepton number violating (LNV) $K^\pm$ decays due to contact dimension-9 (dim-9) quark-lepton effective interactions that are induced at a high energy scale. In this work we…

We develop a "precision-ready", model-independent EFT framework that connects general leptophilic gauge interactions to their low-energy manifestations in SMEFT and LEFT. Starting from a broad U(1)'_ell extension in which leptons carry…