Rubin-LSST

Research group

Research theme

Sub department

About

Measurement of the tt̄ production cross section in pp̄ collisions at s=1.96TeV using lepton+jets events with jet probability b-tagging

Physical Review D - Particles, Fields, Gravitation and Cosmology 74:7 (2006)

Authors:

A Abulencia, D Acosta, J Adelman, T Affolder, T Akimoto, MG Albrow, D Ambrose, S Amerio, D Amidei, A Anastassov, K Anikeev, A Annovi, J Antos, M Aoki, G Apollinari, JF Arguin, T Arisawa, A Artikov, W Ashmanskas, A Attal, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, H Bachacou, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, F Bedeschi, S Behari, S Belforte, G Bellettini, J Bellinger, A Belloni, E Ben Haim, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, D Carlsmith, R Carosi, S Carron, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, J Chapman, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, I Cho, K Cho, D Chokheli, JP Chou, PH Chu, SH Chuang, K Chung, WH Chung, YS Chung, M Ciljak, CI Ciobanu

Abstract:

We present a measurement of the tt̄ production cross section using events with one charged lepton and jets from pp̄ collisions at a center-of-mass energy of 1.96 TeV. A b-tagging algorithm based on the probability of displaced tracks coming from the event interaction vertex is applied to identify b quarks from top decay. Using 318pb-1 of data collected with the CDF II detector, we measure the tt̄ production cross section in events with at least one restrictive (tight) b-tagged jet and obtain 8.9-1.0+1.0(stat)-1.0+1.1(syst)pb. The cross section value assumes a top quark mass of mt=178GeV/c2 in the acceptance corrections. The dependence of the cross section on mt is presented in the paper. This result is consistent with other CDF measurements of the tt̄ cross section using different samples and analysis techniques, and has similar systematic uncertainties. We have also performed consistency checks by using the b-tagging probability function to vary the signal-to-background ratio and also using events that have at least two b-tagged jets. © 2006 The American Physical Society.
More details from the publisher

A very brief description of LOFAR - the Low Frequency Array

(2006)

Authors:

H Falcke, MP van Haarlem, AG de Bruyn, R Braun, HJA Röttgering, B Stappers, WHWM Boland, HR Butcher, EJ de Geus, L Koopmans, R Fender, J Kuijpers, GK Miley, RT Schilizzi, C Vogt, RAMJ Wijers, M Wise, WN Brouw, JP Hamaker, JE Noordam, T Oosterloo, L Bähren, MA Brentjens, SJ Wijnholds, JD Bregman, WA van Cappellen, AW Gunst, GW Kant, J Reitsma, K van der Schaaf, CM de Vos
More details from the publisher

The modulated emission of the ultraluminous X-ray source in NGC 3379

Astrophysical Journal 650:2 I (2006) 879-884

Authors:

G Fabbiano, DW Kim, T Fragos, V Kalogera, AR King, L Angelini, RL Davies, JS Gallagher, S Pellegrini, G Trinchieri, SE Zepf, A Zezas

Abstract:

We report recent Chandra observations of the ULX in the elliptical galaxy NGC 3379 that clearly detect two flux variability cycles. Comparing these data with the Chandra observation of ∼5 years ago, we measure a flux modulation with a period of ∼12.6 hr. Moreover, we find that the emission undergoes a correlated spectral modulation, becoming softer at low flux. We argue that our results establish this source as a ULX binary in NGC 3379. Given the old stellar population of this galaxy, the ULX is likely to be a soft transient; however, historical X-ray sampling suggests that the current "on" phase has lasted ∼10yr. We discuss our results in terms of ADC and wind-feedback models. If the flux modulation is orbital, we can constrain the donor mass and orbital period at the onset of mass transfer within 1.15-1.4 Ṁ and 12.5-17 hr, respectively. The duration of the mass transfer phase so far is probably ∼ 1 Gyr, and the binary has been a soft X-ray transient throughout this time. These constraints are insensitive to the mass of the accretor. © 2006. The American Astronomical Society. All rights reserved.
More details from the publisher

LOFAR - Opening up a new window on the Universe

(2006)

Authors:

HJA Rottgering, R Braun, PD Barthel, MP van Haarlem, GK Miley, R Morganti, I Snellen, H Falcke, AG de Bruyn, RB Stappers, WHWM Boland, HR Butcher, EJ de Geus, L Koopmans, R Fender, J Kuijpers, RT Schilizzi, C Vogt, RAMJ Wijers, M Wise, WN Brouw, JP Hamaker, JE Noordam, T Oosterloo, L Bahren, MA Brentjens, SJ Wijnholds, JD Bregman, WA van Cappellen, AW Gunst, GW Kant, J Reitsma, K van der Schaaf, CM de Vos
More details from the publisher

Measurement of the tt̄ production cross section in pp̄ collisions at s=1.96TeV in the all hadronic decay mode

Physical Review D - Particles, Fields, Gravitation and Cosmology 74:7 (2006)

Authors:

A Abulencia, J Adelman, T Affolder, T Akimoto, MG Albrow, D Ambrose, S Amerio, D Amidei, A Anastassov, K Anikeev, A Annovi, J Antos, M Aoki, G Apollinari, JF Arguin, T Arisawa, A Artikov, W Ashmanskas, A Attal, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, F Bedeschi, S Behari, S Belforte, G Bellettini, J Bellinger, A Belloni, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, S Budroni, K Burkett, G Busetto, P Bussey, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, S Carrillo, D Carlsmith, R Carosi, S Carron, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, I Cho, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, M Ciljak, CI Ciobanu, MA Ciocci

Abstract:

We report a measurement of the tt̄ production cross section using the CDF II detector at the Fermilab Tevatron. The analysis is performed using 311pb-1 of pp̄ collisions at s=1.96TeV. The data consist of events selected with six or more hadronic jets with additional kinematic requirements. At least one of these jets must be identified as a b-quark jet by the reconstruction of a secondary vertex. The cross section is measured to be σtt̄=7. 5±2.1(stat.)-2.2+3.3(syst.)-0.4+0.5(lumi.)pb, which is consistent with the standard model prediction. © 2006 The American Physical Society.
More details from the publisher