Related papers: Constraining the axial-vector X17 interpretation w…
In view of the latest experimental results recently released by the ATOMKI collaboration, we critically re-examine the possible theoretical interpretation of the observed anomalies in terms of a new BSM boson $X$ with mass $\sim17\;$MeV. To…
We propose a direct search for the X17 particle, which was conjectured to explain the ATOMKI $^8$Be and $^4$He anomalies, through the dilepton photoproduction process on a nucleon in the photon energy range below or around the pion…
We propose a novel direct search experiment for X17 using the reaction $\gamma D \to e^+ e^- pn$. X17 is a hypothetical particle conjectured by the ATOMKI collaboration to explain anomalous signals around 17 MeV in excited ${}^8$Be,…
We show that the process of Coherent Elastic neutrino (v) Nucleus Scattering (CEvNS) at nuclear reactor experiments has significant sensitivity to the so-called X17 particle, which has been invoked to explain the ATOMKI anomaly, wherein…
Employing the $^{11}$B(p,$\gamma$)$^{12}$C nuclear reaction, the angular correlation of $e^+e^-$ pairs was investigated in the angular range of $40^\circ\Theta\leq 175^\circ$ for five different proton energies between E$_p$ = 1.50 - 2.50…
In recent years, the ATOMKI collaboration has performed a series of measurements of excited nuclei, observing a resonant excess of electron-positron pairs at large opening angles compared to the Standard Model prediction. The excess has…
The so-called $X17$ particle has been proposed in order to explain a very significant resonant behaviour (in both the angular separation and invariant mass) of $e^+e^-$ pairs produced during a nuclear transition of excited $^8$Be, $^4$He…
Recent anomalies observed in $e^+e^-$ nuclear transitions of $^8 \textrm{Be}$, $^4 \textrm{He}$, and $^{12} \textrm{C}$ by the ATOMKI collaboration may hint at the existence of a vector boson with a mass around 17 MeV, referred to as X17.…
The Atomki anomaly puts forward the hypothesis of an $X(17)$ particle to explain the observation. Utilizing experimental data from the Atomki experiments, measurements of the electron's anomalous magnetic moment, beam dump experiments, the…
Observations of anomalies in the electron-positron angular correlations in high-energy decays in $^4$He, $^8$Be, and $^{12}$C have been reported recently by the ATOMKI collaboration. These could be explained by the creation and subsequent…
We present a hypothesis that the anomaly in the folding angle distribution of electron-positron pairs, emitted in the decay of the excited levels of nucleus $^{8}$Be and $^{4}$He can be related to the cluster structure of the decaying…
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…
The Positron Annihilation into Dark Matter Experiment at the Laboratori Nazionali di Frascati has reported an excess of $e^+e^-$ final-state events from positron annihilation on fixed-target atomic electrons. While the global significance…
A recent experimental study of excited $^{8}\!Be$ decay to its ground state reveals an anomaly in the final states angle distribution. This exceptional result is attributed to a new vector gauge boson X(16.7). We study the significance of…
Recent anomalies in $^8$Be and $^4$He nuclear decays can be explained by postulating a fifth force mediated by a new boson $X$. The distributions of both transitions are consistent with the same $X$ mass, 17 MeV, providing kinematic…
The anomalies recently reported in lepton pair transitions of $^8$Be$^*$ and $^4$He nuclei may be attributed to the existence of a feebly interacting light vector boson $X17$. We study the effects of this hypothetical particle in the…
We show that by exploiting the process of Coherent Elastic neutrino (v) Nucleus Scattering (CEvNS), neutrino measurements by nuclear reactor experiments appear to corroborate the evidence of the so-called X17 particle, which has been…
Two recent experimental observations at the ATOMKI Institute of the Hungarian Academy of Sciences (regarding the angular emission pattern of electron-positron pairs from nuclear transitions from excited states in 8Be and 4He) indicate the…
Recent data from the ATOMKI group continues to confirm their claim of the existence of a new $\sim17$ MeV particle. We review and numerically analyze the data and then put into context constraints from other experiments, notably neutrino…
A new electron scattering experiment (E12-21-003) to verify and understand the nature of hidden sector particles, with particular emphasis on the so-called X17 particle, has been approved at Jefferson Lab. The search for these particles is…