Polarized double-virtual amplitudes for heavy-quark pair production

Chen, L.; Czakon, M.; Poncelet, Rene

doi:10.1007/jhep03(2018)085

Cited by 23 publications

(24 citation statements)

References 69 publications

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“…(5) (or similar variance for the color-octet channels), where the analytic helicity amplitudes for a heavy quark pair production are known in the literature (see, e.g., in Ref. [50]). The final differential cross sections of DPS 2 are obtained via Eq.…”

Section: A Double Parton Scatteringmentioning

confidence: 99%

J/ψ meson production in association with an open charm hadron at the LHC: A reappraisal

Shao

2020

Phys. Rev. D

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We critically (re)examine the associated production process of a J=ψ meson plus an open charm hadron at the LHC in the proton-proton (pp) and proton-lead (pPb) collisions. Such a process is very intriguing in the sense of tailoring to explore the double parton structure of nucleons and to determine the geometry of partons in nuclei. In order to interpret the existing pp data with the LHCb detector at the center-of-mass energy ffiffi ffi s p ¼ 7 TeV, we introduce two overlooked mechanisms for the double parton scattering (DPS) and single parton scattering (SPS) processes. Besides the conventional DPS mode, where the two mesons are produced almost independently in the two separate scattering subprocesses, we propose a novel DPS mechanism that the two constituent (heavy) quarks stemming from two hard scatterings can form into a composite particle, like the J=ψ meson, during the hadronization phase. It yields a strong correlation in the final state from the two distinct scattering subprocesses per hadron-hadron collision. Such a mechanism should be ubiquitous for quarkonium associated production processes involving more-than-one pair of same-flavor heavy quarks. However, it turns out the corresponding contribution is small in J=ψ þ cc hadroproduction. On the contrary, we point out that the resummation of the initial state logarithms due to gluon splitting into a charm quark pair is crucial to understand the LHCb measurement, which was overlooked in the literature. We perform a proper matching between the perturbative calculations in different initial-quark flavor number schemes, generically referring to the variable flavor number scheme. The new variable flavor number scheme calculation for the process strongly enhances the SPS cross sections, almost closing the discrepancies between theory and experiment. Finally, we present our predictions for the forthcoming LHCb measurement in pPb collisions at ffiffiffiffiffiffiffiffi s NN p ¼ 8.16 TeV. Some interesting observables are exploited to set up the control regions of the DPS signal and to probe the impactparameter-dependent parton densities in lead.

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Section: A Double Parton Scatteringmentioning

confidence: 99%

J/ψ meson production in association with an open charm hadron at the LHC: A reappraisal

Shao

2020

Phys. Rev. D

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“…A key ingredient to these calculations are the two-loop QCD corrections to the matrix elements for top pair production in quark-antiquark annihilation and gluon fusion. While numerical representations of these two-loop matrix elements were derived already some time ago [10,11], only partial analytical results are available for them up to now [12][13][14][15] (and used in partial validations [16,17] of the total NNLO cross section calculation). Such analytical results allow in-depth investigations into the structure of the matrix elements, enabling to investigate limiting behaviors and analyticity structures, as well as providing an independent approach to their numerical evaluation.…”

Section: Introductionmentioning

confidence: 99%

Master integrals for the NNLO virtual corrections to $$ q\overline{q}\to t\overline{t} $$ scattering in QCD: the non-planar graphs

Vita

Gehrmann

Laporta

et al. 2019

J. High Energ. Phys.

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We complete the analytic evaluation of the master integrals for the two-loop non-planar box diagrams contributing to the top-pair production in the quark-initiated channel, at next-to-next-to-leading order in QCD. The integrals are determined from their differential equations, which are cast into a canonical form using the Magnus exponential. The analytic expressions of the Laurent series coefficients of the integrals are expressed as combinations of generalized polylogarithms, which we validate with several numerical checks. We discuss the analytic continuation of the planar and the non-planar master integrals, which contribute to qq → tt in QCD, as well as to the companion QED scattering processes ee → µµ and eµ → eµ.

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“…Following [29,30] we employ a hybrid renormalisation scheme where the gluon field G µ and the top quark mass m t are in the on-shell scheme while the strong coupling constant α s is renormalised in the MS scheme. We have…”

Section: Pole Structurementioning

confidence: 99%

Contribution of third generation quarks to two-loop helicity amplitudes for W boson pair production in gluon fusion

Brønnum-Hansen¹,

Wang²

2021

J. High Energ. Phys.

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Polarized double-virtual amplitudes for heavy-quark pair production

Cited by 23 publications

References 69 publications

J/ψ meson production in association with an open charm hadron at the LHC: A reappraisal

J/ψ meson production in association with an open charm hadron at the LHC: A reappraisal

Master integrals for the NNLO virtual corrections to $$ q\overline{q}\to t\overline{t} $$ scattering in QCD: the non-planar graphs

Contribution of third generation quarks to two-loop helicity amplitudes for W boson pair production in gluon fusion

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