Search for the Photoexcitation of Exotic Mesons in the π+π+π− System

A search for exotic mesons in the π+π+π− system photoproduced by the charge exchange reaction γp→π+π+π−(n) was carried out by the CLAS Collaboration at Jefferson Lab. A tagged-photon beam with energies in the 4.8 to 5.4 GeV range, produced through bremsstrahlung from a 5.744 GeV electron beam, was incident on a liquid-hydrogen target. A partial wave analysis was performed on a sample of 83 000 events, the highest such statistics to date in this reaction at these energies. The main objective of this study was to look for the photoproduction of an exotic JPC=1−+ resonant state in the 1 to 2 GeV mass range. Our partial wave analysis shows production of the a2(1320) and the π2(1670) mesons, but no evidence for the a1(1260), nor the π1(1600) exotic state at the expected levels. An upper limit of 13.5 nb is determined for the exotic π1(1600) cross section, less than 2% of the a2(1320) production

Search for the Photoexcitation of Exotic Mesons in the \u3ci\u3eπ\u3c/i\u3e​\u3csup\u3e+\u3c/sup\u3e\u3ci\u3eπ\u3c/i\u3e\u3csup\u3e​+\u3c/sup\u3e\u3ci\u3eπ\u3c/i\u3e\u3csup\u3e-\u3c/sup\u3e System

A search for exotic mesons in the π+π+π- system photoproduced by the charge exchange reaction γp → π+π+π- was carried out by the CLAS Collaboration at Jefferson Lab. A tagged-photon beam with energies in the 4.8 to 5.4 GeV range, produced through bremsstrahlung from a 5.744 GeV electron beam, was incident on a liquid-hydrogen target. A partial wave analysis was performed on a sample of 83 000 events, the highest such statistics to date in this reaction at these energies. The main objective of this study was to look for the photoproduction of an exotic JPC = 1-+ resonant state in the 1 to 2 GeV mass range. Our partial wave analysis shows production of the a2(1320) and the π2(1670) mesons, but no evidence for the a1(1260), nor the π1(1600) exotic state at the expected levels. An upper limit of 13.5 nb is determined for the exotic π1(1600) cross section, less than 2% of the a2(1320) production

Magnetic fluctuations in frustrated Laves hydrides R(Mn_{1-x}Al_{x})_{2}H_{y}

By neutron scattering, we have studied the spin correlations and spin fluctuations in frustrated Laves hydrides, where magnetic disorder sets in the topologically frustrated Mn lattice. Below the transition towards short range magnetic order, static spin clusters coexist with fluctuating and alsmost uncorrelated spins. The magnetic response shows a complexe lineshape, connected with the presence of the magnetic inhomogeneities. Its analysis shows the existence of two different processes, relaxation and local excitations, for the spin fluctuations below the transition. The paramagnetic fluctuations are discussed in comparison with classical spin glasses, cluster glasses, and non Fermi liquid itinerant magnets

Determination of organic pollutants in sediment & some commercial species biota from eastern waters of Hormozgan province

This survey was conducted to determine the petroleum pollutants in sediment & some commercial aquatics of species in eastern waters of Hormozgan province during 2006-2008. We have selected 3 stations at 5, 10 and 20 meters depth in each of Sirik, Kuh-e-mobarak and Jask area. The selected biota were Penaeus indicus & Psettodes eruemi.Selected components of PAHs in sediment & biota samples were: Naphthalene (Na), Acenaphthylene (AcPY), Acenaphthene (AcP), Fluorene (FL), Phenantheren (PHEN), Anthracene (AN), Fluornthene (FLUR), Pyrene (PY), Benzo(a)anthracene (BaA), Chrysene(CHRY), Benzo(b) fluoranthene (BaF), Benzo(k)fluoranthene (BkF), Benzo(a) pyrene (BaP), Dibenzo(a,h)anthrancene (dBAn), Benzo(ghi)perylene (BPe), Indeno (1,2.3-cd)pyrene (IcdP) . Our results were: Based to our results Bioaccumulation of PAHs didn't relate to sex and length of selected biota. Percent of naphthalene as a PAH with two rings has a significant difference against other PAHs in all areas. High ratio of HPAH to LPAH, show the combustion source of PAHs. Values for total PAHs at shrimp in Sirik, Kuh-e- mobarak & Jask area were 349.9 ±236.7, 809.1± 605.4 & 1015±1300.1 ng/g. Values for total PAHs at Psettodes eruemi, in Sirik, Kuh-e- mobarak & Jask area were 494 ±460.8, 1465.3±1678.2 and 292.3±400.7 ng/g respectively. In shrimp samples, the values for total PAHs had significant difference between Jask & Kuh e-mobarak, whereas for Psettodes eruemi, the significant difference was observed in Jask & Kuh-e-mobark. In sediment, concentration of total PAHs and their components didn't show any significant difference with area and depth of sampling at 95% confidence level. Average concentration of total PAHs and their components with 2, 3, 4, 5and 6 rings were 279.7±117.4, 4.5± 9.3, 6.2±7.1, 5.4±1.4, 263.6±113.9 respectively. Based to NOAA standards, pollution level of sediment is lower than ERL values

Measurement of the Muon Decay Parameter delta

The muon decay parameter delta has been measured by the TWIST collaboration. We find delta = 0.74964 +- 0.00066(stat.) +- 0.00112(syst.), consistent with the Standard Model value of 3/4. This result implies that the product Pmuxi of the muon polarization in pion decay, Pmu, and the muon decay parameter xi falls within the 90% confidence interval 0.9960 < Pmuxi < xi < 1.0040. It also has implications for left-right-symmetric and other extensions of the Standard Model.Comment: Extended to 5 pages. Referee's comments answere

Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System

The exclusive reaction $\pi^- p \to \eta \pi^0 n$, $\eta \to \pi^+ \pi^- \pi^0$ at 18 GeV$/c$ has been studied with a partial wave analysis on a sample of 23~492 $\eta \pi^0 n$ events from BNL experiment E852. A mass-dependent fit is consistent with a resonant hypothesis for the $P_+$ wave, thus providing evidence for a neutral exotic meson with $J^{PC} = 1^{-+}$, a mass of $1257 \pm 20 \pm 25$ MeV$/c^2$, and a width of $354 \pm 64 \pm 60$ MeV$/c^2$. New interpretations of the meson exotics in neutral $\eta \pi^0$ system observed in E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase variations. p4, rewording paragrath "The second method ..." . p4, at the bottom of paragrath "The third method ..." added consistent with the results of methods 1 and 2

Search for Exotic Mesons in pi- P Interactions at 18 GeV/c

The recent search for non $q \bar{q}$ mesons in $\pi^{-}p$ interactions at Brookhaven National Laboratory is summarized. Many final states such as $\eta \pi$, $\eta' \pi^{-}$, $a_{0} \pi$, $f_{1} \pi$, $a_{2} \pi$, $b_{1} \pi$, which are favored decay modes of exotics, are under investigation.Comment: 9 pages, PostScript, Presented at the International School of Nuclear Physics, Erice, Sicily, Italy, September 199

Exotic Meson Production in the f1(1285)π−f_{1}(1285)\pi^{-} System observed in the Reaction π−p→ηπ+π−π−p\pi^{-} p \to \eta\pi^{+}\pi^{-}\pi^{-} p at 18 GeV/c

This letter reports results from the partial wave analysis of the $\pi^{-}\pi^{-}\pi^{+}\eta$ final state in $\pi^{-}p$ collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin, parity and charge conjugation, $J^{PC} = 1^{-+}$ in the decay channel $f_{1}(1285)\pi^{-}$. The mass $M = 1709 \pm 24 \pm 41$ MeV/c^2 and width $\Gamma = 403 \pm 80 \pm 115$ MeV/c^2 of the first state are consistent with the parameters of the previously observed $\pi_{1}(1600)$. The second resonance with mass $M = 2001 \pm 30 \pm 92$ MeV/c^2 and width $\Gamma = 333 \pm 52 \pm 49$ MeV/c^2 agrees very well with predictions from theoretical models. In addition, the presence of $\pi_{2}(1900)$ is confirmed with mass $M = 2003 \pm 88 \pm 148$ MeV/c^2 and width $\Gamma = 306 \pm 132 \pm 121$ MeV/c^2 and a new state, $a_{1}(2096)$, is observed with mass $M = 2096 \pm 17 \pm 121$ MeV/c^2 and width $\Gamma = 451 \pm 41 \pm 81$ MeV/c^2. The decay properties of these last two states are consistent with flux tube model predictions for hybrid mesons with non-exotic quantum numbers