A new anomaly observed in ${}^4$He supports the existence of the hypothetical X17 particle

Abstract

Energy-sum and angular correlation spectra of $e^{+}{e}^{-}$ pairs produced in the ${}^3$H(p,$\gamma$)${}^4$He nuclear reaction have been studied at $E_p$=510, 610 and 900 keV proton energies. The main features of the spectra can be understood by taking into account the internal and external pair creations following the direct proton radiative capture by ${}^3$H. However, these processes cannot account for the observed peak around 115${}^{\circ }$ in the angular correlation spectra. This anomalous excess of $e^{+}{e}^{-}$ pairs can be described by the creation and subsequent decay of a light particle during the direct capture process. The derived mass of the particle is $m_{\mathrm{X}}{c}^2$=16.94$\pm 0.12(stat)\pm 0.21(syst)$~MeV. According to the mass and branching ratio ($B_x=5.1(13)\times 10^{-6}$), this is likely the same X17 particle, which we recently suggested [Phys. Rev. Lett. 116, 052501 (2016)] for describing the anomaly observed in the decay of ${}^8$Be.

5 pages, 4 figures. arXiv admin note: text overlap with arXiv:1910.10459

References in corpus (11)

• Secluded WIMP Dark Matter
• The RooFit toolkit for data modeling
• Particle Physics Models for the 17 MeV Anomaly in Beryllium Nuclear Decays
• Atomki Anomaly in Family-Dependent $U(1{)}^{\prime }$ Extension of the Standard Model
• Can a protophobic vector boson explain the ATOMKI anomaly?
• Signals of the QCD axion with mass of 17 MeV/c^2: nuclear transitions and light meson decays
• Is There a Sign of New Physics in Beryllium Transitions?
• Open string QED meson description of the X17 particle and dark matter
• Challenges for a QCD Axion at the 10 MeV Scale
• Search for new light vector boson using $J/\Psi$ at BESIII and Belle II
• First results on the performance of the PADME electromagnetic calorimeter

Cited by in corpus (32)

• 50 Years of Quantum Chromodynamics
• Flavor probes of axion-like particles
• New anomaly observed in ${}^{12}$C supports the existence and the vector character of the hypothetical X17 boson
• Anomalies in Particle Physics
• QED Meson Description of the X17 and Other Anomalous Particles
• The X17 boson and the ${}^3$H$(p,e^{+}{e}^{-}{)}^4$He and ${}^3$He$(n,e^{+}{e}^{-}{)}^4$He processes: a theoretical analysis
• Search for pseudoscalar bosons decaying into $e^{+}{e}^{-}$ pairs in the NA64 experiment at the CERN SPS
• Resonant search for the X17 boson at PADME
• An updated view on the ATOMKI nuclear anomalies
• Neutrino Constraints and the ATOMKI X17 Anomaly
• Displaced Searches for Light Vector Bosons at Belle II
• Checking the ${}^8$Be anomaly with a two-arm electron positron pair spectrometer
• A 17 MeV pseudoscalar and the LSND, MiniBooNE and ATOMKI anomalies
• Search for a new 17 MeV resonance via $e^{+}{e}^{-}$ annihilation with the PADME Experiment
• On the Atomki nuclear anomaly after the MEG-II result
• Ab initio investigation of the ${}^7$Li($p,e^{+}{e}^{-}$)${}^8$Be process and the X17 boson
• Primordial black-hole formation and heavy r-process element synthesis from the cosmological QCD transition. Two aspects of an inhomogeneous early Universe
• Hunting for a 17 MeV particle coupled to electrons
• On the question of quark confinement in the Abelian U(1) QED gauge interaction
• Dynamics of quarks and gauge fields in the lowest-energy states in QCD and QED
• ARIEL experiments and theory
• QED meson description of the anomalous particles at ~17 and ~38 MeV
• Probing the ATOMKI X17 vector boson using Dalitz decays $V\to P{e}^{+}{e}^{-}$
• From oversimplified to overlooked: the case for exploring Rich Dark Sectors
• Novel approach to investigate ATOMKI anomaly using Coherent CAPTAIN-Mills detectors
• New Physics contamination to precision luminosity measurements at future $e^{+}{e}^{-}$ colliders
• Field equation of thermodynamic gravity and galactic rotational curves
• Radiative and Dalitz decays of ${\rm Y}(1S)$ in the light of the ATOMKI X17 anomaly
• Green's Function Formalism for Impurity-Induced Resonances in Sub-barrier Proton-Nucleus Scattering
• Contributions to $Z^0$ decays from a X17 extension of the Standard Model
• Flavor specific chiral $U(1{)}_X$ framework for explaining the ATOMKI anomaly
• Dark hyperCharge Symmetry