Simultaneous measurement of forward-backward asymmetry and top polarization in dilepton final states from tt¯ production at the Tevatron

Abazov, V. M. and Abbott, B. and Acharya, B. S. and Adams, M. and Adams, T. and Agnew, J. P. and Alexeev, G. D. and Alkhazov, G. and Alton, A. and Askew, A. and Atkins, S. and Augsten, K. and Avila, C. and Badaud, F. and Bagby, L. and Baldin, B. and Bandurin, D. V. and Banerjee, S. and Barberis, E. and Baringer, P. and Bartlett, J. F. and Bassler, U. and Bazterra, V. and Bean, A. and Begalli, M. and Bellantoni, L. and Beri, S. B. and Bernardi, G. and Bernhard, R. and Bertram, I. and Besanifmmode çelse çon, M. and Beuselinck, R. and Bhat, P. C. and Bhatia, S. and Bhatnagar, V. and Blazey, G. and Blessing, S. and Bloom, K. and Boehnlein, A. and Boline, D. and Boos, E. E. and Borissov, G. and Borysova, M. and Brandt, A. and Brandt, O. and Fox, H. and Price, D. and Ratoff, P. N. and Ross, A. and Williams, M. R. J. (2015) Simultaneous measurement of forward-backward asymmetry and top polarization in dilepton final states from tt¯ production at the Tevatron. Physical Review D, 92 (5). ISSN 1550-7998

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We present a simultaneous measurement of the forward-backward asymmetry and the top-quark polarization in tt¯ production in dilepton final states using 9.7  fb−1 of proton-antiproton collisions at s√=1.96  TeV with the D0 detector. To reconstruct the distributions of kinematic observables we employ a matrix element technique that calculates the likelihood of the possible tt¯ kinematic configurations. After accounting for the presence of background events and for calibration effects, we obtain a forward-backward asymmetry of Att¯=(15.0±6.4(stat)±4.9(syst))% and a top-quark polarization times spin analyzing power in the beam basis of κP=(7.2±10.5(stat)±4.2(syst))%, with a correlation of −56% between the measurements. If we constrain the forward-backward asymmetry to its expected standard model value, we obtain a measurement of the top polarization of κP=(11.3±9.1(stat)±1.9(syst))%. If we constrain the top polarization to its expected standard model value, we measure a forward-backward asymmetry of Att¯=(17.5±5.6(stat)±3.1(syst))%. A combination with the D0 Att¯ measurement in the lepton+jets final state yields an asymmetry of Att¯=(11.8±2.5(stat)±1.3(syst))%. Within their respective uncertainties, all these results are consistent with the standard model

Item Type:
Journal Article
Journal or Publication Title:
Physical Review D
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© 2015 American Physical Society Published: 22/9/2015, Received 22/7/2015 Evidence of Acceptance not available
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Deposited On:
21 Oct 2015 04:59
Last Modified:
30 May 2020 03:54