Search for narrow states in the inclusive gamma ray spectra resulting from antiproton annihilations at rest in liquid hydrogen and deuterium

摘要

The energy spectrum of gamma rays produced in proton-antiproton annihilation at rest in hydrogen and deuterium has been measured with good energy resolution and high statistics. The data were taken using the PS183 magnetic pair spectrometer at LEAR (CERN). A detailed search of the gamma spectrum yielded no evidence of gamma transitions to narrow states with widths consistent with the spectrometer resolution. In hydrogen, upper limits (95% CL) are obtained for the yield of narrow states of 2--5 (times) 10(sup (minus)4) for states below 1,700 MeV/c(sup 2), and 5--10 (times) 10(sup (minus)4) for states between 1,700 and 1,800 MeV/c(sup 2). In deuterium, the corresponding upper limits are, 1--7 (times) 10(sup (minus)3) for masses between 700 and 1, 730 MeV/c(sup 2), and 1--2 (times) 10(sup (minus)3) for masses between 1,750 and 1,835 MeV/c(sup 2). These results contradict reports of the observation of narrow lines made by previous experiments. Valid pacs appear here.