Search

We report here on an experiment done at the 30-GeV proton synchrotron at Brookhaven National Laboratory using a large-acceptance ($delta$m=1 GeV) pair spectrometer with a mass resolution of plus-or-minus5 MeV, to search for additional long-lived particles which decay into K$sup -$$pi$$sup +$, K$sup +$$pi$$sup -$, pp, K$sup +$K$sup -$, $pi$$sup +$$pi$$sup -$, K$sup -$p, $pi$$sup - $p, K$sup +$p, or $pi$$sup +$p. The result, based on 2times10$sup 7$ events, shows that, to a sensitivity comparable to or lower than the production of J particles (production) times (decay branching ratio) approx. =10$sup -34$ cm$sup 2$, no additional states were found.

The invariant cross section for the inclusive production of ..pi../sup +/, ..pi../sup -/, K/sup +/, K/sup -/, p, and p-bar is presented for proton-nucleon interactions at p/sub lab/=28.5 GeV/c. Beryllium, titanium, and tungsten targets were used and the yields were extrapolated to A=1 using the power law sigmaapprox.A/sup ..cap alpha../. The exponent ..cap alpha.. increases with p/sub T/, except for protons. The p/sub T/ dependence of the cross sections is compared with a simple fireball model. (AIP)

We report the observation of a heavy particle $J$, with mass $m=3.1$ GeV and width approximately zero. The observation was made from the reaction $p+\mathrm{Be}\ensuremath{\rightarrow}{e}^{+}+{e}^{\ensuremath{-}}+x$ by measuring the ${e}^{+}{e}^{\ensuremath{-}}$ mass spectrum with a precise pair spectrometer at the Brookhaven National Laboratory's 30-GeV alternating-gradient synchrotron.

We report here the observation of surprisingly simple behaviors in the massive-hadron-pair (m>2 GeV) production from proton-nucleon collisions. With a 28.6-GeV incident proton beam and a pair spectrometer to detect the hadrons, the measured cross section decreases like d$sup 2$sigma/dxdmproportionale$sup -5$/ subm/ and can be grouped into three groups: $pi$$sup -$+p; $pi$$sup +$+$pi$$sup - $, p+p, K$sup -$+p; and K$sup -$+$pi$$sup +$, $pi$$sup +$+p. Within a given group the yield is the same to plus-or-minus20%; different groups are separated by a factor of approx.10 from each other.