BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., & Oyanguren, A. (2012). Study of the reaction e(+)e(-) -> J/psi pi(+)pi(-) via initial-state radiation at BABAR. Phys. Rev. D, 86(5), 051102–9pp.
Abstract: We study the process e(+)e(-) -> J/psi pi(+)pi(-) with initial-state-radiation events produced at the PEP-II asymmetric-energy collider. The data were recorded with the BABAR detector at center-of-mass energies 10.58 and 10.54 GeV, and correspond to an integrated luminosity of 454 fb(-1). We investigate the J/psi pi(+)pi(-) mass distribution in the region from 3.5 to 5.5 GeV/c(2). Below 3.7 GeV/c(2) the psi (2S) signal dominates, and above 4 GeV/c(2) there is a significant peak due to the Y(4260). A fit to the data in the range 3.74-5.50 GeV/c(2) yields a mass value 4245 +/- 5(stat) +/- 4(syst) MeV/c(2) and a width value 114(-15)(+16)(stat) +/- 7(syst) MeV for this state. We do not confirm the report from the Belle Collaboration of a broad structure at 4.01 GeV/c(2). In addition, we investigate the pi(+)pi(-) system which results from Y(4260) decay.
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Martinez Torres, A., Bayar, M., Jido, D., & Oset, E. (2012). Strategy to find the two Lambda (1405) states from lattice QCD simulations. Phys. Rev. C, 86(5), 055201–13pp.
Abstract: Theoretical studies within the chiral unitary approach, and recent experiments, have provided evidence of the existence of two isoscalar states in the region of the Lambda(1405). In this paper we use the same chiral approach to generate energy levels in a finite box. In a second step, assuming that these energies correspond to lattice QCD results, we devise the best strategy of analysis to obtain the two states in the infinite-volume case, with sufficient precision to distinguish them. We find out that by using energy levels obtained with asymmetric boxes and/or with a moving frame, with reasonable errors in the energies, one has a successful scheme to get the two Lambda(1405) poles.
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AGATA Collaboration(Soderstrom, P. A. et al), & Gadea, A. (2012). High-spin structure in K-40. Phys. Rev. C, 86(5), 054320–9pp.
Abstract: High-spin states of K-40 have been populated in the fusion-evaporation reaction C-12(Si-30,np)K-40 and studied by means of gamma-ray spectroscopy techniques using one triple-cluster detector of the Advanced Gamma Tracking Array at the Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro. Several states with excitation energy up to 8 MeV and spin up to 10(-) have been discovered. These states are discussed in terms of J = 3 and T = 0 neutron-proton hole pairs. Shell-model calculations in a large model space have shown good agreement with the experimental data for most of the energy levels. The evolution of the structure of this nucleus is here studied as a function of excitation energy and angular momentum.
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NOMAD Collaboration(Kullenberg, C. T. et al), Cervera-Villanueva, A., & Gomez-Cadenas, J. J. (2012). A search for single photon events in neutrino interactions. Phys. Lett. B, 706(4-5), 268–275.
Abstract: We present a search for neutrino induced events containing a single, exclusive photon using data from the NOMAD experiment at the CERN SPS where the average energy of the neutrino flux is similar or equal to 25 GeV. The search is motivated by an excess of electron-like events in the 200-475 MeV energy region as reported by the MiniBooNE experiment. In NOMAD, photons are identified via their conversion to e(+)e(-) in an active target embedded in a magnetic field. The background to the single photon signal is dominated by the asymmetric decay of neutral pions produced either in a coherent neutrino-nucleus interaction, or in a neutrino-nucleon neutral current deep inelastic scattering, or in an interaction occurring outside the fiducial volume. All three backgrounds are determined in situ using control data samples prior to opening the 'signal-box'. In the signal region, we observe 155 events with a predicted background of 129.2 +/- 8.5 +/- 3.3. We interpret this as null evidence for excess of single photon events, and set a limit. Assuming that the hypothetical single photon has a momentum distribution similar to that of a photon from the coherent pi(0) decay, the measurement yields an upper limit on single photon events, < 4.0 x 10(-4) per nu(mu) charged current event. Narrowing the search to events where the photon is approximately collinear with the incident neutrino, we observe 78 events with a predicted background of 76.6 +/- 4.9 +/- 1.9 yielding a more stringent upper limit, < 1.6 x 10(-4) per nu(mu) charged current event.
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ATLAS Collaboration(Aad, G. et al), Amoros, G., Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Escobar, C., et al. (2012). Measurement of the W -> tau nu(tau) cross section in pp collisions at root s=7 TeV with the ATLAS experiment. Phys. Lett. B, 706(4-5), 276–294.
Abstract: The cross section for the production of W bosons with subsequent decay W -> tau nu(tau) is measured with the ATLAS detector at the LHC. The analysis is based on a data sample that was recorded in 2010 at a proton-proton center-of-mass energy of root s = 7 TeV and corresponds to an integrated luminosity of 34 pb(-1). The cross section is measured in a region of high detector acceptance and then extrapolated to the full phase space. The product of the total W production cross section and the W -> tau nu(tau) branching ratio is measured to be sigma(tot)(W -> tau nu tau) = 11.1 +/- 0.3 (stat) +/- 1.7 (syst) +/- 0.4 (lumi) nb. (C) 2011 CERN.
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