Taprogge, J. et al, Gadea, A., & Montaner-Piza, A. (2014). Identification of a millisecond isomeric state in Cd-129(81) via the detection of internal conversion and Compton electrons. Phys. Lett. B, 738, 223–227.
Abstract: The decay of an isomeric state in the neutron-rich nucleus Cd-129 has been observed via the detection of internal conversion and Compton electrons providing first experimental information on excited states in this nucleus. The isomer was populated in the projectile fission of a U-238 beam at the Radioactive Isotope Beam Factory at RIKEN. From the measured yields of gamma-rays and internal conversion electrons, a multipolarity of E3 was tentatively assigned to the isomeric transition. A half-life of T-1/2 = 3.6(2) ms was determined for the new state which was assigned a spin of (21/2(+)), based on a comparison to shell model calculations performed using state-of-the-art realistic effective interactions.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2014). Fiducial and differential cross sections of Higgs boson production measured in the four-lepton decay channel in pp collisions at root s=8 TeV with the ATLAS detector. Phys. Lett. B, 738, 234–253.
Abstract: Measurements of fiducial and differential cross sections of Higgs boson production in the H -> ZZ* -> 4l decay channel are presented. The cross sections are determined within a fiducial phase space and corrected for detection efficiency and resolution effects. They are based on 20.3 fb(-1) of pp collision data, produced at root s= 8 TeV centre-of-mass energy at the LHC and recorded by the ATLAS detector. The differential measurements are performed in bins of transverse momentum and rapidity of the four-lepton system, the invariant mass of the subleading lepton pair and the decay angle of the leading lepton pair with respect to the beam line in the four-lepton rest frame, as well as the number of jets and the transverse momentum of the leading jet. The measured cross sections are compared to selected theoretical calculations of the Standard Model expectations. No significant deviation from any of the tested predictions is found.
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ATLAS Collaboration(Aad, G. et al), Cabrera Urban, S., Castillo Gimenez, V., Costa, M. J., Ferrer, A., Fiorini, L., et al. (2014). Search for new resonances in W gamma and Z gamma final states in pp collisions at root s=8 TeV with the ATLAS detector. Phys. Lett. B, 738, 428–447.
Abstract: This Letter presents a search for new resonances decaying to final states with a vector boson produced in association with a high transverse momentum photon, V gamma, with V = W(-> l nu) or Z(-> l(+)l(-)), where l = μor mu. The measurements use 20.3fb(-1) of proton-proton collision data at a center-of-mass energy of root s = 8 TeV recorded with the ATLAS detector. No deviations from the Standard Model expectations are found, and production cross section limits are set at 95% confidence level. Masses of the hypothetical a(T) and omega(T) states of a benchmark Low Scale Technicolor model are excluded in the ranges [275, 960] GeV and [200, 700]boolean OR[750, 890] GeV, respectively. Limits at 95% confidence level on the production cross section of a singlet scalar resonance decaying to Z gamma final states have also been obtained for masses below 1180 GeV.
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AGATA Collaboration(Pellegri, L. et al), & Gadea, A. (2014). Pygmy dipole resonance in Sn-124 populated by inelastic scattering of O-17. Phys. Lett. B, 738, 519–523.
Abstract: The gamma decay from the high-lying states of Sn-124 was measured using the inelastic scattering of O-17 at 340 MeV. The emitted gamma rays were detected with high resolution with the AGATA demonstrator array and the scattered ions were detected in two segmented Delta E-E silicon telescopes. The angular distribution was measured both for the gamma rays and the scattered O-17 ions. An accumulation of E1 strength below the particle threshold was found and compared with previous data obtained with (gamma,gamma') and (alpha,alpha'gamma) reactions. The present results of elastic scattering, and excitation of E2 and E1 states were analysed using the DWBA approach. From this comprehensive description the isoscalar component of the 1-excited states was extracted. The obtained values are based on the comparison of the data with DWBA calculations including a form factor deduced using a microscopic transition density.
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BABAR Collaboration(Lees, J. P. et al), Martinez-Vidal, F., Oyanguren, A., & Villanueva-Perez, P. (2014). Measurements of direct CP asymmetries in B -> X-s gamma decays using sum of exclusive decays. Phys. Rev. D, 90(9), 092001–12pp.
Abstract: We measure the direct CP violation asymmetry, A(CP), in B -> X-s gamma and the isospin difference of the asymmetry, Delta A(CP), using 429 fb(-1) of data collected at Upsilon(4S) resonance with the BABAR detector at the PEP- II asymmetric- energy e(+)e(-) storage rings operating at the SLAC National Accelerator Laboratory. B mesons are reconstructed from ten charged B final states and six neutral B final states. We find A(CP) = +(1.7 +/- 1.9 +/- 1.0)%, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between A(CP) for charged and neutral decay modes, Delta A(CP) = +(5.0 +/- 3.9 +/- 1.5)%. Using the value of Delta A(CP), we also provide 68% and 90% confidence intervals on the imaginary part of the ratio of theWilson coefficients corresponding to the chromomagnetic dipole and the electromagnetic dipole transitions.
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