On the nature of new baryon state X(2000) observed in the experiments with the SPHINX spectrometer
Abstract
Description
In the experiment with the SPHINX spectrometer in 1995-99 a new baryon state X(2000) -> Sigma^0K^+ was observed in the proton diffractive reactions p + N(C) -> Sigma^0K^+ + N(C). The main parameters of X(2000)^+ baryon are M = 1986 +- 6 MeV, Gamma = 98 +- 21 MeV. Unusual features of massive X(2000) state (narrow decay width Gamma/M simeq 0.05, anomalously large branching ratio with strange particle emission) make it serious candidate for cryptoexotic pentaquark baryon with hidden strangeness. New data on the SPHINX with by an order of magnitude enlarge statistics are in agreement with previous data and are supported our conclusions. We propose further studies X(2000) baryon production in the meson reactions with baryon exchange: pi^{+-} + p -> X(2000)^+ + pi^{+-} OZI - forbidden suppressed reaction for the state |qqqsbar{s}>) and K^{+-} + p -> X(2000)^+ + K^{+-} (OZI - allowed reaction). If the value of R=BR[pi^{+-} + p -> X(2000)^+ + pi^{+-}]/BR[K^{+-}+p -> X(2000)^+ + K^{+-}]<<1 it will be the crucial argument in favor of X(2000)= |qqqsbar{s}>) structure. These experiments may be done on IHEP separated kaon beam with OKA spectrometer.
7 pages 11 figures
7 pages 11 figures