Related papers: X17 discovery potential in the $\gamma N \rightarr…
Recent experimental observations, most notably those reported by the ATOMKI and Positron Annihilation into Dark Matter Experiment (PADME) collaborations, have hinted anomalies that may indicate the presence of a new resonance with a mass…
We show that the X17 vector boson, introduced to explain the ^8 Be anomalous decay, could play a crucial role in the explanation of the muon's (electron's) anomalous magnetic moment and the muonic Lamb shift. We further constrain the…
Rare leptonic kaon and pion decays $K^+(\pi^+) \to \mu^+\, \nu_{\mu}\, e^+ e^-$ can be used to probe a dark photon of mass ${\cal O}(10)$~MeV, with the background coming from the mediation of a virtual photon. This is most relevant for the…
We discuss a set of precision observables that can probe the existence of a light particle $X$ coupled to electrons in the mass range of 1-100 MeV. As a case study, we consider the recent excess of $e^+e^-$ final-state events at $\sqrt{s} =…
The reduced cross sections of the semi-exclusive $(l,l'p)$ lepton scattering process can be identified with distorted nuclear spectral functions. Irrespective of the type of interaction the distorted spectral function is determined mainly…
In our quest to understand the nature of dark matter and discover its non-gravitational interactions with ordinary matter, we propose an experiment using a \pbo ~calorimeter to search for or set new limits on the production rate of i)…
An inclusive search for anomalous production of two prompt, isolated leptons with the same electric charge is presented. The search is performed in a data sample corresponding to 4.7 fb-1 of integrated luminosity collected in 2011 at…
The quasielastic charged current (CCQE) $\nu_e n \rightarrow e^- p$ scattering is the dominant mechanism to detect appearance of a $\nu_e$ in an almost $\nu_\mu$ flux at the 1 GeV scale. Actual experiments show a precision below 1% and…
In recent electron-positron angular correlation measurements the observed significant enhancements relative to the internal pair creation at large angles was interpreted as indication of the creation of $J^{\pi }=1^{+}$ boson called X17…
We revisit the gauged $U(1)_{B-L}$ explanation of the ATOMKI nuclear anomalies, in which the new gauge boson is the hypothetical $X(17)$ particle. It is known that the vanilla $B-L$ scenario is unable to account for appropriate couplings,…
Massive photon-like particles are predicted in many extensions of the Standard Model with a hidden sector where dark matter is secluded. They are vector bosons mediating the interaction between dark matter particles and can be produced in…
We present MicroBooNE's first search for dark sector $e^+e^-$ explanations of the long-standing MiniBooNE anomaly. The MiniBooNE anomaly has garnered significant attention over the past 20 years including previous MicroBooNE investigations…
Positrons beam dump experiments have unique features to search for very narrow resonances coupled superweakly to $e^+ e^-$ pairs. Due to the continue loss of energy from soft photon bremsstrahlung, in the first few radiation lengths of the…
We report measurements of differential cross sections and decay asymmetries of incoherent $\phi$-meson photoproduction from the deuteron at forward angles using linearly polarized photons at \Eg=1.5-2.4 GeV. The nuclear transparency ratio…
We study the prospects of detecting signals of a resonant scattering of high-energy cosmic neutrinos on electrons in the atmosphere. Such a process is possible through an s-channel exchange of a isotriplet scalar particle predicted by some…
The Gamma Factory is a proposal to back-scatter laser photons off a beam of partially-stripped ions at the LHC, producing a beam of $\sim 10$ MeV to $1$ GeV photons with intensities of $10^{16}$ to $10^{18}~\text{s}^{-1}$. This implies…
Some black holes in X-ray binaries accrete at rates far above the Eddington limit. In this supercritical regime, photons are trapped in a radiation-dominated, geometrically thick disk. The innermost regions form a complex environment of…
We describe an experiment to search for a new vector boson A' with weak coupling alpha' > 6 x 10^{-8} alpha to electrons (alpha=e^2/4pi) in the mass range 65 MeV < m_A' < 550 MeV. New vector bosons with such small couplings arise naturally…
Events containing a pair of charged leptons and significant missing transverse momentum are selected from a data sample corresponding to a total integrated luminosity of 20.6 pb^-1 at centre-of-mass energies of 161 GeV and 172 GeV. The…
The dark matter and existence of new particles are now a possible explanation of several physics phenomena which evade the predictions of the Standard Model. In this context Axion-Like-Particles (ALP) with masses in the MeV to GeV range…