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Off-shell effects for t-channel and s-channel single-top production at next-to-leading order in QCD

P. Falgari, F. Giannuzzi, P. Mellor, and A. Signer
Phys. Rev. D 83, 094013 – Published 10 May 2011
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  • INTRODUCTION
  • CALCULATION
  • RESULTS
  • CONCLUSION
  • ACKNOWLEDGEMENTS
    • References

    Abstract

    In this work we present a calculation of both t-channel and s-channel single-top production at next-to-leading order in QCD for the Tevatron and for the LHC at a center-of-mass energy of 7 TeV. All the cross sections and kinematical distributions presented include leading nonfactorizable corrections arising from interferences of the production and decay subprocesses, extending previous results beyond the narrow-width approximation. The new off shell effects are found to be generally small, but can be sizeable close to kinematical endpoints and for specific distributions.

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    • Received 28 February 2011

    DOI:https://doi.org/10.1103/PhysRevD.83.094013

    © 2011 American Physical Society

    Authors & Affiliations

    P. Falgari1, F. Giannuzzi2, P. Mellor3, and A. Signer3

    • 1Institute for Theoretical Physics and Spinoza Institute, Utrecht University, 3508 TD Utrecht, The Netherlands
    • 2Dipartimento di Fisica, Università degli Studi di Bari, I-70126 Bari, Italy and I.N.F.N., Sezione di Bari, I-70126 Bari, Italy
    • 3IPPP, Department of Physics, University of Durham, Durham DH1 3LE, England

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    Vol. 83, Iss. 9 — 1 May 2011

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    Images

    • Figure 1
      Figure 1
      Correspondence between the expansion by regions and the effective-theory calculation: hard loops (top left) coincide with corrections to the matching coefficient of the production vertex (top right), whereas soft loops (bottom left) reproduce the effect of loop diagrams in the effective theory (bottom right).Reuse & Permissions
    • Figure 2
      Figure 2
      Scale dependence of the total cross section for pp¯→JbJle+ET (left) and pp¯→JbJb¯e+ET (right) at the Tevatron. The plot shows the LO cross section with LO (dashed blue) and NLO (solid blue) PDFs, and the NLO cross section with simultaneous variation of factorization and renormalization scale (solid red) and for fixed factorization scale (dashed red).Reuse & Permissions
    • Figure 3
      Figure 3
      Top invariant mass distributions for the process pp¯→JbJle+ET+X (upper plot) and pp¯→JbJb¯e+ET+X (lower plot) at the Tevatron. The blue band represents the LO ET result, the red band the NLO ET result, and the green curve the NLO spin-correlated NWA prediction. For the ET results the band width is obtained by varying the factorization and renormalization scales in the interval mt/4≤μR=μF≤mt. The lower panels show the NWA result divided by the NLO ET result to illustrate the off shell effects.Reuse & Permissions
    • Figure 4
      Figure 4
      Kinematical distributions for pp¯→JbJle+ET+X at the Tevatron. Top: top quark transverse mass (left) and hadronic transverse energy (right). Center: top quark transverse momentum (left) and top quark pseudorapidity (right). Bottom: e+νJh invariant mass (left) and cosθS (right). See the text for a precise definition of the observables and further explanations.Reuse & Permissions
    • Figure 5
      Figure 5
      Kinematical distributions for pp¯→JbJb¯e+ET+X at the Tevatron. Top: top quark transverse mass (left) and JbJb¯ invariant mass (right). Center: top quark transverse momentum (left) and top quark rapidity (right). Bottom: e+νeJb¯ invariant mass (left) and cosθB (right). See the text for a precise definition of the observables and further explanations.Reuse & Permissions
    • Figure 6
      Figure 6
      Scale dependence of the total cross section for pp→JbJle+ET (left) and pp→JbJb¯e+ET (right) at the 7 TeV LHC. The plot shows the LO cross section with LO (dashed blue) and NLO (solid blue) PDFs, and the NLO cross section with simultaneous variation of factorization and renormalization scale (solid red) and for fixed factorization scale (dashed red).Reuse & Permissions
    • Figure 7
      Figure 7
      Top invariant mass distributions for the process pp→JbJle+ET (upper plot) and pp→JbJb¯e+ET (lower plot) at the 7 TeV LHC. The blue band represents the LO ET result, the red band the NLO ET result, and the green curve the NLO spin-correlated NWA prediction. For the ET results the band width is obtained by varying the factorization and renormalization scales in the interval mt/4≤μR=μF≤mt. The lower panels show the NWA result divided by the NLO ET result to illustrate the off shell effects.Reuse & Permissions
    • Figure 8
      Figure 8
      Kinematical distributions for pp→JbJle+ET+X for the 7 TeV LHC. Top: top quark transverse mass (left) and hadronic transverse energy (right). Center: top quark transverse momentum (left) and top quark pseudorapidity (right). Bottom: e+νJh invariant mass (left) and cosθS (right). See the text for a precise definition of the observables and further explanations.Reuse & Permissions
    • Figure 9
      Figure 9
      Kinematical distributions for pp→JbJb¯e+ET+X for the 7 TeV LHC. Top: top quark transverse mass (left) and JbJb¯ invariant mass (right). Center: top quark transverse momentum (left) and top quark rapidity (right). Bottom: e+νeJb¯ invariant mass (left) and cosθB (right). See the text for a precise definition of the observables and further explanations.Reuse & Permissions
    • Figure 10
      Figure 10
      Normalized top quark rapidity distributions for t-channel production at the LHC. Leading-order results are shown in blue and next-to-leading-order results in red. Solid and dashed lines represent contributions proportional to |Vtb|2 and |Vtd|2, respectively.Reuse & Permissions
    • Figure 11
      Figure 11
      Kinematical distributions for pp→JbJle+ET+X for the 7 TeV LHC with the cuts shown in Table  applied. Top: top quark transverse mass (left) and hadronic transverse energy (right). Center: top quark transverse momentum (left) and top quark pseudorapidity (right). Bottom: e+νJh invariant mass (left) and cosθS (right). See the text for a precise definition of the observables and further explanations.Reuse & Permissions
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