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Tevatron Combination of Single-Top-Quark Cross Sections and Determination of the Magnitude of the Cabibbo-Kobayashi-Maskawa Matrix Element $\bf V_{tb}$

CDF Collaboration, D0 Collaboration

TL;DR

The final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV is presented.

Abstract

We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb$^{-1}$ per experiment. The $t$-channel cross section is measured to be $σ_t = 2.25^{+0.29}_{-0.31}$ pb. We also present the combinations of the two-dimensional measurements of the $s$- vs. $t$-channel cross sections and of the $s+t$ channel cross section measurement resulting in $σ_{s+t} = 3.30^{+0.52}_{-0.40}$ pb, without assuming the standard-model value for the ratio $σ_s/σ_t$. The resulting value of the magnitude of the top-to-bottom quark coupling is $|V_{tb}|$ = $1.02^{+0.06}_{-0.05}$, corresponding to $|V_{tb}| > 0.92$ at the 95% C.L.

Tevatron Combination of Single-Top-Quark Cross Sections and Determination of the Magnitude of the Cabibbo-Kobayashi-Maskawa Matrix Element $\bf V_{tb}$

TL;DR

The final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV is presented.

Abstract

We present the final combination of CDF and D0 measurements of cross sections for single-top-quark production in proton-antiproton collisions at a center-of-mass energy of 1.96 TeV. The data correspond to total integrated luminosities of up to 9.7 fb per experiment. The -channel cross section is measured to be pb. We also present the combinations of the two-dimensional measurements of the - vs. -channel cross sections and of the channel cross section measurement resulting in pb, without assuming the standard-model value for the ratio . The resulting value of the magnitude of the top-to-bottom quark coupling is = , corresponding to at the 95% C.L.

Paper Structure

This paper contains 1 section, 2 equations, 4 figures.

Table of Contents

  1. Acknowledgments

Figures (4)

  • Figure 1: Distribution of the mean discriminants for bins with similar ratios of ($s$-channel$-$$t$-channel) signals divided by background yields. The data, predicted SM $s$- and $t$-channel yields, and expected background are displayed. The total expected background (black solid line) is shown with its uncertainty (gray shaded band). A nonlinear scale is used on the abscissa to better display the range of the discriminant output values.
  • Figure 2: Two-dimensional posterior probability as a function of $\sigma_t$ and $\sigma_s$ with one s. d. (68% C.L.), two s.d. (95% C.L.), and three s. d. (99.7% C.L.) probability contours for the combination of the CDF and D0 analysis channels compared with the NLO+NNLL theoretical prediction of the SM schannel-kidonakistchannel-kidonakis. Several BSM predictions are shown, a model with four quark families with top-to-strange quark coupling $|V_{ts}| = 0.2$FourthGen2, a top-flavor model with new heavy bosons with mass $m_x = 1$ TeV Tait:2000sh, a model of charged top pions with mass $m_{\pi^{\pm}} = 250$ GeV Tait:2000sh, and a model with flavor-changing neutral currents with a 0.036 coupling $\kappa_u/\Lambda$ between up quark, top quark, and gluon Tait:2000shd0-fcnc.
  • Figure 3: Measured single-top-quark production cross sections from the CDF and D0 Collaborations in different production channels and the Tevatron combinations of these analyses compared with the NLO+NNLL theoretical prediction schannel-kidonakistchannel-kidonakis.
  • Figure 4: Posterior probability distribution as a function of $|V_{tb}|^2$ for the combination of CDF and D0 analysis channels. The arrow indicates the allowed values of $|V_{tb}|^2$ corresponding to the limit of $|V_{tb}| > 0.92$ at the $95\%$ C.L.