Observation of a narrow structure in1H(γ,KS0)

M. J. Amaryan

¹

,

G. Gavalian

²

,

C. S. Nepali

³

et al.

Abstract

We report observation of a narrow peak structure at ∼1.54 GeV with a Gaussian width σ = 6 MeV in the missing mass of KS in the reaction γ + p → pKSKL. The observed structure may be due to the interference between a strange (or anti-strange) baryon resonance in the pKL system and the φ(KSKL) photoproduction leading to the same final state. The statistical significance of the observed excess of events estimated as the log likelihood ratio of the resonant signal+background hypothesis and the φ-production based background-only hypothesis corresponds to 5.3σ.

Observation of a narrow baryon resonance with positive strangeness formed inK+Xe collisions

“…Moreover, increasing the statistics of the charge-exchange reaction allowed DIANA to directly estimate the + intrinsic width: 0.4 ± 0.1 MeV [7,8]. More recently, observation of a narrow peak near 1.54 GeV in the missing mass of the K 0 S meson in the reaction γp → K 0 S K 0 L p was reported by a group from the CLAS Collaboration [9]. Other searches for the + baryon in different reactions and experimental conditions yielded both positive and negative results; see the review papers [10] and [11] and references therein.…”

Neutron anomaly inγN→ηNand the flavour SU(3) symmetry

“…The reanalysis of the CLAS data using the K L K S pairs from the decay of φ-meson the was performed in Ref. [47]. The observation of a narrow peak structure at ∼ 1.54 GeV with a Gaussian width of ∼ 6 MeV in the missing mass of K S was reported.…”

EPECUR setup for the search for narrow baryon resonances in pion-proton scattering

“…container bottom, (3) body, (4) aluminum ring, (5) beryllium shell, (6) vacuum tight housing, (7) transparent diaphragm, (8,9) removal pipes of the heat exchanger, and (10) telescopic tube.…”

“…At the same instant of time, flip flop Т 0 is reset to zero, trans ferring the system to the ready state. It is important that, over this time, the logic state of flip flops Т 1 -Т 8 propagates over the entire internal logic of the FPGA system, and the signals at inputs Dr 1 -Dr 3 are set to certain values. Therefore, the used approach offers a chance to meet strict requirements for FPGA signal clocking and to provide timing of the output triggering signals to the instant of counter С 1 operation.…”

“…The CLASS collaboration analyzed a large body of statistical data, but managed only to estimate the upper limit on the θ + photoproduction cross section [7]. Thereafter, while selecting events in the region of interference with a ϕ meson, a team from this collab oration observed a reliable signal of this resonance [8]. Therefore, the question about the existence of θ + remains open.…”