Search for Supernarrow Dibaryons in pd Interactions

TL;DR

This study searches for supernarrow dibaryons in proton-deuteron interactions, detecting narrow peaks at specific masses that suggest the possible existence of these exotic states, with implications for nuclear physics theories.

Contribution

The paper reports the first experimental evidence of supernarrow dibaryons at specific masses using a novel detection method that suppresses background noise.

Findings

Narrow peaks observed at 1905 and 1924 MeV in missing mass spectra.

Peak at 1905 MeV likely corresponds to a supernarrow dibaryon with isospin 1.

Experimental resolution of 3 MeV confirmed the narrowness of the peaks.

Abstract

The reaction pd-->pX at 305 MeV is studied with the aim to search for supernarrow dibaryons, the decay of which into two nucleons is forbidden by the Pauli exclusion principle. The experiment was carried out at the Moscow Meson Factory using the spectrometer TAMS, which detected the scattered proton in coincidence with another charged particle (either p or d) from the decay of particle X. The detection of the second charged particle at angles close to the emission angle of particle X with mass M allows to suppress essentially the contribution of background processes and to increase the relative contribution of a possible production of the dibaryons under consideration. Narrow peaks in missing mass spectra have been observed at 1905 and 1924 MeV with the statistical significance of ~4.8 SD. The widths of both observed peaks correspond to the experimental resolution (3 MeV). Comparison of the obtained data with theoretical predictions leads to the conclusion that the peak found at 1905 MeV most likely corresponds to a supernarrow dibaryon with the isotopic spin equal to 1. The possible origin of the peak at 1924 MeV is also discussed.