Search for new particles decaying into electron pairs of mass below 100 MeV/c²

Abstract

We report results on 1220 electron pairs produced from a 207Pb beam at 160 A GeV in nuclear emulsion with invariant mass Q ranging between 1 and 100 MeV and lifetime τ between 10−15 s and 10−12 s. These electron pairs were produced at a distance of more than 50 µm from the primary interactions—this distance eliminates contamination due to Dalitz pairs. After subtracting the background pairs from the materialization of photons and also due to the decay of π0 → 2γ from the data, they exhibit enhancement at low mass Q = 6–20 MeV with narrow peaks at 7 ± 1 MeV, 19 ± 1 MeV and τ ⩽ 10−13 s.

Open string QED meson description of the X17 particle and dark matter

“…Supporting evidence for this hypothetical X17 particle has been reported recently in the decay of the excited I(J π ) = 0(0 − ) state of 4 He [16]. Earlier observations of similar e + e − pairs with invariant masses between 3 to 20 MeV in the collision of nuclei with emulsion detectors have been reported [17][18][19][20][21][22]. Different theoretical interpretations, astrophysical implications, and experimental searches have been presented [2][3][4][5][6][7][8][9][10][11][12][13][14][15].…”

Viscous Modified Cosmic Chaplygin Gas Cosmology

“…An important problem is determining nature of dark Universe. It is found that the dark matter may be consists of neutrinos [1] axions [2] or WIMPs (weak interactive massive particles) [3]. In that case there are several ways to specify the nature of the dark Universe.…”

A cyclic universe with colour fields

“…of the electron, might also reveal itself at low energies through synchronisation between the constituents of the composite electrons in ferromagnetic electron liquids [179] and lowdimensional electron systems, like Wigner crystals [180]. Another possibility is to detect some exotic electron bound states, like those observed by Jain and Singh [181] in their experiments at CERN aimed at searching for low-mass neutral particles decaying into e + e − pairs. They have reported the detection of short-lived neutral particles having masses of 7 ± 1 MeV and 19 ± 1 MeV.…”