Theoretical introduction

• Claudio Toni (Istituto Nazionale di Fisica Nucleare)
• Claudio Toni
• Claudio Toni (Sapienza)

Room: Aula Conversi

MEG-II

• Francesco Renga (Istituto Nazionale di Fisica Nucleare)

Room: Aula Conversi

Probing the existence and properties of the X7 boson using proton and neutron beams

• Carlo Gustavino (Istituto Nazionale di Fisica Nucleare)

Room: Aula Conversi Three significant anomalies have been observed in the emission of electron-positron pairs in the 7Li(p,e+e−)8Be, 3H(p,e+e−)4He and 11B(p,e+e−)12C nuclear reactions [1-3]. These anomalies have been interpreted as the signature of the existence of a boson (hereafter referred to as X17) of mass MX17 = 16.8 MeV/c2 that could be a mediator of a fifth force, characterised by a strong coupling suppression of protons compared to neutrons (protophobic force). In this talk is presented a new experimental approach to clarify the present scenario, by searching for the X17 boson in the decay of excited A=3,4 (Tritium, helium-3, helium-4) nuclei through reactions induced by protons or neutrons. The study of the 3He(n,e+e−)4He and 3H(p,e+e−)4He reaction, in a wide energy window and using a detector with a large angular acceptance would probe the X17 existence and quantic numbers. In the case of a positive result, the study of the 2H(n,e+e−)3He and 2H(p,e+e−)3H would show the kinematic onset of the X17 channel at Ebeam~>16 MeV and offers the opportunity to shed light on the isospin dependence of the X17-nucleon coupling. The achievable results are discussed on the base of ab-initio calculations, in which the existence of a 17 MeV boson is considered [4,5]. [1] A. J. Krasznahorkay et al., Phys. Rev. Lett. 116, (2016) 042501. [2] A. J. Krasznahorkay et al., Phys. Rev. C 104, (2021) 044003. [3] A. J. Krasznahorkay et al., Phys. Rev. C 106, (2022) 061601. [4] M. Viviani et al., Phys. Rev. C 105, 014001 (2022), arXiv:2104.07808 [nucl-th]. [5] M. Viviani et al., submitted to Phys. Rev. C. arXiv:2408.16744.

Other initiatives and PADME

• Mauro Raggi (Istituto Nazionale di Fisica Nucleare)

Room: Aula Conversi

X17 production and electron motion pitfalls

• Luc Darmé (Laboratori Nazionali di Frascati)
• Luc DARME (IP2I - Lyon 1 University)
• Luc Jean Marie Darmé

Room: Aula Conversi

Discussion Room: Aula Conversi

Coffee break Room: Aula Conversi