No abstract

Differential cross sections for the reaction γ p → n π + have been measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged photon beam with energies from 0.725 to 2.875 GeV. Where available, the results obtained here compare well with previously published results for the reaction. Agreement with the SAID and MAID analyses is found below 1 GeV. The present set of cross sections has been incorporated into the SAID database, and exploratory fits have been made up to 2.7 GeV. Resonance couplings have been extracted and compared to previous determinations. With the addition of these cross sections to the world data set, significant changes have occurred in the high-energy behavior of the SAID cross-section predictions and amplitudes.

Because of their long lifetimes, the ω and ϕ mesons are the ideal candidates for the study of possible modifications of the in-medium meson-nucleon interaction through their absorption inside the nucleus. During the E01-112 experiment at the Thomas Jefferson National Accelerator Facility, the mesons were photoproduced from 2H, C, Ti, Fe, and Pb targets. This Letter reports the first measurement of the ratio of nuclear transparencies for the e+e- channel. The ratios indicate larger in-medium widths compared with what have been reported in other reaction channels. The absorption of the ω meson is stronger than that reported by the CBELSA-TAPS experiment and cannot be explained by recent theoretical models.

We argue that the existence of a new narrow (Γ ≤ 25 MeV) nucleon resonance N * (1685) is strongly supported by recent data on η photoproduction off the nucleon. The resonance has much stronger photo-coupling to the neutron than to the proton. This nucleon resonance is a good candidate for the non-strange member of the exotic anti-decouplet of baryons -the partner of the pentaquark Θ + . All up to date known properties of new N * (1685) are summarized. PACS: 13.60.Le, 14.20.Gk 1) For brevity we call this enhancement "neutron anomaly".

The search for double beta-decay of 76 Ge was carried out with a detector fabricated of enriched material (85% abundance of 76 Ge compared with 7.8% natural abundance). Measurements have been performed by the ITEP/YePI team in the Avan salt mine, 245 meters underground, situated in Yerevan, Armenia. Evidence for two-neutrino double beta-decay of 76 Ge with half-life of T1/2(2v)=(9±1) · 1020 y was obtained. New limits for neutrinoless double beta-decay, T1/2(0v)>1.3×1024 y, and double beta-decay with majoron emission T1/2(0v, B)>1×1022 y were obtained at 68% CL from mean background fluctuations. Limit for 0v-decay derived by the maximum likelihood method was T1/2>2.0×1024 y.