Observation of a J^PC = 1-+ exotic resonance in diffractive dissociation of 190 GeV/c pi- into pi- pi- pi+

The COMPASS experiment at the CERN SPS has studied the diffractive dissociation of negative pions into the pi- pi- pi+ final state using a 190 GeV/c pion beam hitting a lead target. A partial wave analysis has been performed on a sample of 420000 events taken at values of the squared 4-momentum transfer t' between 0.1 and 1 GeV^2/c^2. The well-known resonances a1(1260), a2(1320), and pi2(1670) are clearly observed. In addition, the data show a significant natural parity exchange production of a resonance with spin-exotic quantum numbers J^PC = 1-+ at 1.66 GeV/c^2 decaying to rho pi. The resonant nature of this wave is evident from the mass-dependent phase differences to the J^PC = 2-+ and 1++ waves. From a mass-dependent fit a resonance mass of 1660 +- 10+0-64 MeV/c^2 and a width of 269+-21+42-64 MeV/c^2 is deduced.Comment: 7 page, 3 figures; version 2 gives some more details, data unchanged; version 3 updated authors, text shortened, data unchange

The Polarised Valence Quark Distribution from semi-inclusive DIS

The semi-inclusive difference asymmetry A^{h^{+}-h^{-}} for hadrons of opposite charge has been measured by the COMPASS experiment at CERN. The data were collected in the years 2002-2004 using a 160 GeV polarised muon beam scattered off a large polarised ^6LiD target and cover the range 0.006 < x < 0.7 and 1 < Q^2 < 100 (GeV/c)^2. In leading order QCD (LO) the asymmetry A_d^{h^{+}-h^{-}} measures the valence quark polarisation and provides an evaluation of the first moment of Delta u_v + Delta d_v which is found to be equal to 0.40 +- 0.07 (stat.) +- 0.05 (syst.) over the measured range of x at Q^2 = 10 (GeV/c)^2. When combined with the first moment of g_1^d previously measured on the same data, this result favours a non-symmetric polarisation of light quarks Delta u-bar = - Delta d-bar at a confidence level of two standard deviations, in contrast to the often assumed symmetric scenario Delta u-bar = Delta d-bar = Delta s-bar = Delta s.Comment: 7 pages, 3 figures, COMPASS, revised: details added, author list update

Tiny hitchhikers and parasites: a review of Australian heterostigmatic mites (Acari: Prostigmata) associated with insects, with description of three new species

Heterostigmatic mites (Heterostigmata) are highly diverse, have symbiotic associations with various insects and occur worldwide. Despite Australia's rich insect biodiversity, little is known about its heterostigmatic mites. In this study, we conducted a preliminary study on heterostigmatic mites associated with beetles in eastern Australia and found four species, of which three were new: Caraboacarus stammeri Krczal, 1959 (Caraboacaridae) and Eutarsopolipus orpheus Katlav & Seeman, sp. nov., (Podapolipidae) associated with Australian-endemic Gnathaphanus melbournensis (Castelnau, 1867) (Carabidae); Hoplocheylus australiensis Katlav & Seeman, sp. nov., (Tarsocheylidae) phoretic on Australian-endemic Mastachilus quaestionis (Kuwert, 1891) (Passalidae); and Pavania gazellatris Katlav & Seeman, sp. nov., (Dolichocybidae) phoretic on introduced Digitonthophagus gazella (Fabricius, 1787) (Scarabaeidae). The species of Caraboacaridae, Dolichocybidae and Tarsocheylidae are the first species records of these families in Australia. It is likely that two of the three new species are Australian endemics, while P. gazellatris may be a more recent arrival on introduced dung beetles, possibly arriving with imports of exotic adult dung beetles. Furthermore, we provide an overview of the heterostigmatic mite fauna of Australia that consists of less than 90 species belonging to 13 families, with representatives of all known seven superfamilies. These mites have so far been mostly reported on beetles but also on other insect orders (Blattodea, Diptera, Hemiptera, Hymenoptera, Orthoptera, Thysanoptera). Our findings of three new species and one new record based on the analysis of a relatively small number of specimens and beetle species suggest that more comprehensive studies of host insect taxa will reveal a substantially larger Australian diversity of heterostigmatic mites