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Author |
ATLAS Collaboration (Aad, G. et al); Cabrera Urban, S.; Castillo Gimenez, V.; Costa, M.J.; Ferrer, A.; Fiorini, L.; Fuster, J.; Garcia, C.; Garcia Navarro, J.E.; Gonzalez de la Hoz, S.; Hernandez Jimenez, Y.; Higon-Rodriguez, E.; Irles Quiles, A.; Kaci, M.; Lacasta, C.; Lacuesta, V.R.; Marti-Garcia, S.; Miñano, M.; Mitsou, V.A.; Moles-Valls, R.; Moreno Llacer, M.; Oliver Garcia, E.; Perez Garcia-Estañ, M.T.; Romero Adam, E.; Ros, E.; Salt, J.; Sanchez Martinez, V.; Solans, C.A.; Soldevila, U.; Sanchez, J.; Torro Pastor, E.; Valladolid Gallego, E.; Valls Ferrer, J.A.; Villaplana Perez, M.; Vos, M.; Wildauer, A. |
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Title |
Evidence for the associated production of a W boson and a top quark in ATLAS at root s=7 TeV |
Type |
Journal Article |
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Year |
2012 |
Publication |
Physics Letters B |
Abbreviated Journal |
Phys. Lett. B |
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Volume |
716 |
Issue |
1 |
Pages |
142-159 |
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Keywords |
ATLAS; Top quark; W plus t; Single top-quark |
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Abstract |
This Letter presents evidence for the associated production of a W boson and a top quark using 2.05 fb(-1) of pp collision data at root s = 7 TeV accumulated with the ATLAS detector at the LHC. The analysis is based on the selection of the dileptonic final states with events featuring two isolated leptons, electron or muon, with significant transverse missing momentum and at least one jet. An approach based on boosted decision trees has been developed to improve the discrimination of single top-quark Wt events from background. A template fit to the final classifier distributions is performed to determine the cross-section. The result is incompatible with the background-only hypothesis at the 3.3 sigma level, the expected sensitivity assuming the Standard Model production rate being 3.4 sigma. The corresponding cross-section is determined and found to be sigma(wt) = 16.8 +/- 2.9 (stat) +/- 4.9 (syst) pb, in good agreement with the Standard Model expectation. From this result the CKM matrix element vertical bar V-tb vertical bar = 1.03(-0.19)(+0.16) is derived assuming that the Wt production through vertical bar V-ts vertical bar and vertical bar V-td vertical bar is small. (C) 2012 CERN. Published by Elsevier B.V All rights reserved. |
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Address |
[Akdogan, T.; Arik, E.; Arik, M.; Istin, S.; Ozcan, V. E.; Rador, T.] Bogazici Univ, Dept Phys, Istanbul, Turkey |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0370-2693 |
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Notes |
WOS:000309621400007 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1255 |
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Author |
Vilella, E.; Alonso, O.; Trenado, J.; Vila, A.; Casanova, R.; Vos, M.; Garrido, L.; Dieguez, A. |
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Title |
A test beam setup for the characterization of the Geiger-mode avalanche photodiode technology for particle tracking |
Type |
Journal Article |
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Year |
2012 |
Publication |
Nuclear Instruments & Methods in Physics Research A |
Abbreviated Journal |
Nucl. Instrum. Methods Phys. Res. A |
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Volume |
694 |
Issue |
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Pages |
199-204 |
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Keywords |
The Geiger-mode avalanche photodiode (GAPD); CMOS; EUDET/AIDA telescope; Schottky detector; Test beam; Trigger logic unit (TLU) |
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Abstract |
It is well known that avalanche photodiodes operated in the Geiger mode above the breakdown voltage offer a virtually infinite gain and time accuracy in the picosecond range that can be used for single photon detection. However, their performance in particle detection still remains unexplored. In this contribution, we are going to expose different steps that we have taken in order to prove the efficiency of the Geiger mode avalanche photodiodes in the aforementioned field. In particular, we will present a setup for the characterization of these sensors in a test beam. The expected results of the test beam at DESY and CERN have been simulated with Geant4 and will also be exposed. |
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Address |
[Vilella, E.; Alonso, O.; Vila, A.; Casanova, R.; Dieguez, A.] Univ Barcelona, Dept Elect, E-08028 Barcelona, Spain, Email: evilella@el.ub.es |
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Publisher |
Elsevier Science Bv |
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English |
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ISSN |
0168-9002 |
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Notes |
WOS:000311020500029 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1256 |
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Author |
Bordes, J.; Dominguez, C.A.; Moodley, P.; Peñarrocha, J.; Schilcher, K. |
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Title |
Corrections to the SU(3) x SU(3) Gell-Mann-Oakes-Renner relation and chiral couplings L-8(r) and H-r(2) |
Type |
Journal Article |
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Year |
2012 |
Publication |
Journal of High Energy Physics |
Abbreviated Journal |
J. High Energy Phys. |
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Volume |
10 |
Issue |
10 |
Pages |
102 - 11pp |
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Keywords |
Sum Rules; QCD |
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Abstract |
Next to leading order corrections to the SU(3) x SU(3) Gell-Mann-OakesRenner relation (GMOR) are obtained using weighted QCD Finite Energy Sum Rules (FESR) involving the pseudoscalar current correlator. Two types of integration kernels in the FESR are used to suppress the contribution of the kaon radial excitations to the hadronic spectral function, one with local and the other with global constraints. The result for the pseudoscalar current correlator at zero momentum is psi(5)(0) = (2.8 +/- 0.3) x 10(-3) GeV4, leading to the chiral corrections to GMOR: delta(K) = (55 +/- 5)%. The resulting uncertainties are mostly due to variations in the upper limit of integration in the FESR, within the stability regions, and to a much lesser extent due to the uncertainties in the strong coupling and the strange quark mass. Higher order quark mass corrections, vacuum condensates, and the hadronic resonance sector play a negligible role in this determination. These results confirm an independent determination from chiral perturbation theory giving also very large corrections, i.e. roughly an order of magnitude larger than the corresponding corrections in chiral SU(2) x SU(2). Combining these results with our previous determination of the corrections to GMOR in chiral SU(2) x SU(2), delta(pi), we are able to determine two low energy constants of chiral perturbation theory, i.e. L-8(r) = (1.0 +/- 0.3) x 10(-3), and H-2(r) = -(4.7 +/- 0.6) x 10(-3), both at the scale of the rho-meson mass. |
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Address |
[Bordes, J.; Penarrocha, J.] Univ Valencia, Dept Fis Teor, Valencia, Spain, Email: Jose.M.Bordes@uv.es; |
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Springer |
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English |
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ISSN |
1126-6708 |
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Notes |
WOS:000310851600031 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1257 |
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Author |
de Putter, R.; Mena, O.; Giusarma, E.; Ho, S.; Cuesta, A.; Seo, H.J.; Ross, A.J.; White, M.; Bizyaev, D.; Brewington, H.; Kirkby, D.; Malanushenko, E.; Malanushenko, V.; Oravetz, D.; Pan, K.K.; Percival, W.J.; Ross, N.P.; Schneider, D.P.; Shelden, A.; Simmons, A.; Snedden, S. |
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Title |
New Neutrino Mass Bounds from SDSS-III Data Release 8 Photometric Luminous Galaxies |
Type |
Journal Article |
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Year |
2012 |
Publication |
Astrophysical Journal |
Abbreviated Journal |
Astrophys. J. |
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Volume |
761 |
Issue |
1 |
Pages |
12 - 12pp |
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Keywords |
cosmological parameters; cosmology: observations; large-scale structure of universe |
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Abstract |
We present neutrino mass bounds using 900,000 luminous galaxies with photometric redshifts measured from Sloan Digital Sky Survey III Data Release 8. The galaxies have photometric redshifts between z = 0.45 and z = 0.65 and cover 10,000 deg(2), thus probing a volume of 3 h(-3) Gpc(3) and enabling tight constraints to be derived on the amount of dark matter in the form of massive neutrinos. A new bound on the sum of neutrino masses Sigma m nu < 0.27 eV, at the 95% confidence level (CL), is obtained after combining our sample of galaxies, which we call “CMASS,” with Wilkinson Microwave Anisotropy Probe (WMAP) seven-year cosmic microwave background data and the most recent measurement of the Hubble parameter from the Hubble Space Telescope (HST). This constraint is obtained with a conservative multipole range of 30 < l < 200 in order to minimize nonlinearities, and a free bias parameter in each of the four redshift bins. We study the impact of assuming this linear galaxy bias model using mock catalogs and find that this model causes a small (similar to 1 sigma-1.5 sigma) bias in Omega(DM)h(2). For this reason, we also quote neutrino bounds based on a conservative galaxy bias model containing additional, shot-noise-like free parameters. In this conservative case, the bounds are significantly weakened, e. g., Sigma m(nu) < 0.38 eV (95% CL) for WMAP+HST+CMASS (l(max) = 200). We also study the dependence of the neutrino bound on the multipole range (l(max) = 150 versus l(max) = 200) and on which combination of data sets is included as a prior. The addition of supernova and/or baryon acoustic oscillation data does not significantly improve the neutrino mass bound once the HST prior is included. A companion paper describes the construction of the angular power spectra in detail and derives constraints on a general cosmological model, including the dark energy equation of state w and the spatial curvature Omega(K), while a second companion paper presents a measurement of the scale of baryon acoustic oscillations from the same data set. All three works are based on the catalog by Ross et al. |
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Address |
[de Putter, Roland] Univ Barcelona, ICC, IEEC UB, E-08028 Barcelona, Spain |
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Publisher |
Iop Publishing Ltd |
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English |
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0004-637x |
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Notes |
WOS:000311748800012 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1262 |
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Author |
Seo, H.J. et al; de Putter, R. |
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Title |
Acoustic scale from the angular power spectra of SDSS-III DR8 photometric luminous galaxies |
Type |
Journal Article |
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Year |
2012 |
Publication |
Astrophysical Journal |
Abbreviated Journal |
Astrophys. J. |
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Volume |
761 |
Issue |
1 |
Pages |
13 - 16pp |
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Keywords |
distance scale; cosmological parameters; cosmology: observations; large-scale structure of universe |
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Abstract |
We measure the acoustic scale from the angular power spectra of the Sloan Digital Sky Survey III (SDSS-III) Data Release 8 imaging catalog that includes 872, 921 galaxies over similar to 10,000 deg(2) between 0.45 < z < 0.65. The extensive spectroscopic training set of the Baryon Oscillation Spectroscopic Survey luminous galaxies allows precise estimates of the true redshift distributions of galaxies in our imaging catalog. Utilizing the redshift distribution information, we build templates and fit to the power spectra of the data, which are measured in our companion paper, to derive the location of Baryon acoustic oscillations (BAOs) while marginalizing over many free parameters to exclude nearly all of the non-BAO signal. We derive the ratio of the angular diameter distance to the sound horizon scale D-A(z)/r(s) = 9.212(-0.404)(+0.416) at z = 0.54, and therefore D-A(z) = 1411 +/- 65 Mpc at z = 0.54; the result is fairly independent of assumptions on the underlying cosmology. Our measurement of angular diameter distance D-A(z) is 1.4 sigma higher than what is expected for the concordance Lambda CDM, in accordance to the trend of other spectroscopic BAO measurements for z greater than or similar to 0.35. We report constraints on cosmological parameters from our measurement in combination with the WMAP7 data and the previous spectroscopic BAO measurements of SDSS and WiggleZ. We refer to our companion papers (Ho et al.; de Putter et al.) for investigations on information of the full power spectrum. |
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Address |
[Seo, Hee-Jong] Univ Calif Berkeley, LBL, Berkeley Ctr Cosmol Phys, Berkeley, CA 94720 USA |
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Publisher |
Iop Publishing Ltd |
Place of Publication |
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Editor |
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Language |
English |
Summary Language |
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Original Title |
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Series Editor |
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Abbreviated Series Title |
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Series Volume |
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Series Issue |
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Edition |
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ISSN |
0004-637x |
ISBN |
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Conference |
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Notes |
WOS:000311748800013 |
Approved |
no |
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Is ISI |
yes |
International Collaboration |
yes |
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Call Number |
IFIC @ pastor @ |
Serial |
1264 |
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| Permanent link to this record |
