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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2010). Diffractive W and Z production at the Fermilab Tevatron. Phys. Rev. D, 82(11), 112004–10pp.
Abstract: We report on a measurement of the fraction of events with a W or Z boson which are produced diffractively in (p) over barp collisions at root s = 1.96 TeV, using data from 0.6 fb-1 of integrated luminosity collected with the CDF II detector equipped with a Roman- pot spectrometer that detects the (p) over bar from (p) over bar + p -> (p) over bar + [X + W/Z]. We find that (1.00 +/- 0.11)% of Ws and (0.88 +/- 0.22)% of Zs are produced diffractively in a region of antiproton or proton fractional momentum loss xi of 0.03 < xi < 0.10 and 4-momentum transferred squared t of -1 < t < 0 (GeV/c)(2), where we account for the events in which the proton scatters diffractively while the antiproton dissociates, (p) over bar + p -> [X + W/Z] + p, by doubling the measured proton dissociation fraction. We also report on searches for W and Z production in double Pomeron exchange, (p) over bar + p -> [X + W/Z] + p, and on exclusive Z production, (p) over bar + p -> (p) over bar + Z + p. No signal is seen above background for these processes, and comparisons are made with expectations.
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CDF Collaboration(Aaltonen, T. et al), & Cabrera, S. (2010). Measurement of the top pair production cross section in the dilepton decay channel in p(p)over-bar collisions at root s = 1.96 TeV. Phys. Rev. D, 82(5), 052002–20pp.
Abstract: A measurement of the t (t) over bar production cross section in p (p) over bar collisions at root s = 1.96 TeV using events with two leptons, missing transverse energy, and jets is reported. The data were collected with the CDF II detector. The result in a data sample corresponding to an integrated luminosity 2.8 fb(-1) is sigma(t (t) over bar) = 6.27 +/- 0.73(stat) +/- 0.63(syst) +/- 0.39(lum) pb. for an assumed top mass of 175 GeV/c(2).
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HADES Collaboration(Agakishiev, G. et al), Diaz, J., & Gil, A. (2010). Lambda-p femtoscopy in collisions of Ar + KCl at 1.76AGeV. Phys. Rev. C, 82(2), 021901–5pp.
Abstract: Results on Lambda p femtoscopy are reported at the lowest energy so far. At a beam energy of 1.76AGeV, the reaction Ar + KCl was studied with the High Acceptance Di-Electron Spectrometer ( HADES) at SIS18/GSI. A high-statistics and high-purity Lambda sample was collected, allowing for the investigation of Lambda p correlations at low relative momenta. The experimental correlation function is compared to corresponding model calculations allowing the determination of the space-time extent of the Lambda p emission source. The Lambda p source radius is found to be slightly smaller than the pp correlation radius for a similar collision system. The present Lambda p radius is significantly smaller than that found for Au + Au/Pb + Pb collisions in the AGS, SPS, and RHIC energy domains but larger than that observed for electroproduction from He. Taking into account all available data, we find the Lambda p source radius to increase almost linearly with the number of participants to the power of one-third.
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Mengoni, D. et al, Gadea, A., Algora, A., & Rubio, B. (2010). Lifetime measurements of excited states in neutron-rich Ar-44,Ar-46 populated via a multinucleon transfer reaction. Phys. Rev. C, 82(2), 024308–7pp.
Abstract: Lifetimes of low-lying excited states of the neutron-rich Ar-44,Ar-46 nuclei, populated via multinucleon transfer reactions, are measured by means of the differential recoil distance Doppler shift method. The extracted electromagnetic transition probabilities are compared with previous intermediate-energy Coulomb-excitation measurements and with large-scale shell-model calculations. The increase in the deduced B( E2; 2(+) -> 0(+)) transition probability from Ar-44 to the closed-shell nucleus Ar-46 contradicts the earlier results of Coulomb-excitation experiments. Shell-model calculations using different effective interactions agree with the new measured values.
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Rodriguez-Alvarez, M. J., Sanchez, F., Soriano, A., & Iborra, A. (2010). Sparse Givens resolution of large system of linear equations: Applications to image reconstruction. Math. Comput. Model., 52(7-8), 1258–1264.
Abstract: In medicine, computed tomographic images are reconstructed from a large number of measurements of X-ray transmission through the patient (projection data). The mathematical model used to describe a computed tomography device is a large system of linear equations of the form AX = B. In this paper we propose the QR decomposition as a direct method to solve the linear system. QR decomposition can be a large computational procedure. However, once it has been calculated for a specific system, matrices Q and R are stored and used for any acquired projection on that system. Implementation of the QR decomposition in order to take more advantage of the sparsity of the system matrix is discussed.
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