Anomalous internal pair creation

Péter Kálmán,Tamás Keszthelyi

doi:10.1140/epja/s10050-020-00202-z

Abstract

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 particle. In this paper it is brought up that such enhancements can be generated by higher order processes. It is found that nuclear transitions, the transition energy of which is significantly lower than the whole transition energy, can cause peaked angle dependence in electron-positron angular correlation.

Highlights

The anomalies in the spectra of emitted positrons observed in heavy-ion collisions at GSI (Darmstadt) in the 1980’s [1,2,3,4] inspired experimentalists after the suggestions of [5,6] to search for traces of a short-lived neutral particle [7,8] produced in nuclear decays
The observed significant deviations from internal pair conversion [9,10] sustained the interest [11,12] searching for a light neutral boson [13] which is called X17-boson
In this paper it is shown that effects of nuclear physics origin can contribute to the presence of the observed anomaly

Summary

Introduction

The anomalies in the spectra of emitted positrons observed in heavy-ion collisions at GSI (Darmstadt) in the 1980’s [1,2,3,4] inspired experimentalists after the suggestions of [5,6] to search for traces of a short-lived neutral particle [7,8] produced in nuclear decays. The observed significant deviations from internal pair conversion [9,10] sustained the interest [11,12] searching for a light neutral boson [13] which is called X17-boson. In this paper it is shown that effects of nuclear physics origin can contribute to the presence of the observed anomaly. In the analysis of experiments observing anomalous pair production the possible effect of higher order processes was not taken into account. Higher order coupled reactions, like the ones to be discussed here and which are one joined processes contrary to the former two step one, may happen. It is thought that the anomaly arises if the observed e−e+ coincidences are examined in the light of the two step process only

Statement of this letter

General considerations

Study of the T -matrix element

Summary