Electroweak and QCD corrections to 
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-boson production with one 
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 jet in a massive five-flavor scheme

Figueroa, Diogenes; Honeywell, S.; Quackenbush, Seth; Reina, Laura; Reuschle, Christian; Wackeroth, D.

doi:10.1103/physrevd.98.093002

Cited by 17 publications

(25 citation statements)

References 91 publications

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“…However, in a matched-b framework the massive computation is still beset by the need to start at high perturbative order. As a possible way out, the use of a "massive five flavor scheme" has been suggested recently [7,8], in which there is a b PDF (hence five flavors), yet b quark mass effects are included (possibly, at least in part, also in parton showering). The use of an independently parametrized b quark PDF within a framework in which massive and massless computations are combined offers a simpler way of dealing with the same problem.…”

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confidence: 99%

Fitting the b-quark PDF as a massive-b scheme: Higgs production in bottom fusion

2019

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We show that a simple and accurate approach to the computation of hadron collider processes involving initial-state b quarks can be obtained by introducing an independently parametrized b PDF. We use the so-called FONLL method for the matching of a scheme in which the b quark is treated as a massless parton to that in which it is treated as a massive state, and extend it to the case in which the b quark PDF is not necessarily determined by perturbative matching conditions. This generalizes to hadronic collisions analogous results previously obtained for deep-inelastic scattering. The results corresponds to a "massive b" scheme, in which b mass effects are retained, yet the b quark is endowed with a PDF. We specifically study Higgs production in bottom fusion, and show that our approach overcomes difficulties related to the fact that in a standard massive four-flavor scheme b-quark induced processes only start at high perturbative orders. arXiv:1905.02207v2 [hep-ph] 18 Jul 20191 The treatment of heavy quark PDFs It has been recently shown [1] that for accurate phenomenology at the LHC it is advantageous to treat the charm parton distribution (PDF) on the same footing as light-quark PDFs, namely, to parametrize it and extract it from data, rather than to take it as radiatively generated from the gluon using perturbative matching conditions. This is likely to be due to the fact that matching conditions are only known to the lowest nontrivial order, which may well be subject to large higher order corrections, as revealed by the strong dependence of results on the choice of matching scale. On top of this, of course, the starting low-scale heavy quark PDFs could in principle also have a non-perturbative "intrinsic" component [2,3]. It is important to note that whether or not the heavy quark PDF has a nonperturbative component, and whether it is advantageous to parametrize the heavy quark PDF are separate issues: in fact in Ref. [1] it was shown that the main phenomenological advantage in parametrizing and fitting the charm PDF comes from a region in which any nonperturbative contribution to charm is likely to be extremely small.The case of the bottom quark PDF is, in this respect, particularly interesting. On the one hand, one may think that that the problem of large higher order corrections to the matching conditions is alleviated in this case by the larger value of the mass. However, on the other hand, there is a more subtle consideration. Namely, there are b-initiated hadron collider processes -some of which are especially relevant for new physics searches -such as Higgs production in bottom fusion, for which b quark mass effects might be nonnegligible [4][5][6]. This suggests the use of a scheme in which the b quark is treated as a massive final-state parton -hence not endowed with a PDF. In such a scheme the b-induced process necessarily starts at a higher perturbative order than in a scheme in which there exists a b PDF, because the b production process is included in the hard matrix element. As a consequence, th...

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Fitting the b-quark PDF as a massive-b scheme: Higgs production in bottom fusion

2019

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“…2.2. This process was examined by the authors using NLOX recently [52,53], where particular attention was paid to EW corrections and using a massive b quark. The corresponding fixed-order NLO QCD corrections were first calculated in [91].…”

Section: Pp → Jjmentioning

confidence: 99%

“…Ref. [52] The primary interface for the TRed library is the class TRed, which mangages the storage and computation of all tensor coefficients, and interfaces to external scalar libraries. Here we describe some of its more important interface functions.…”

Section: Appendix A3 Qcd Renormalizationmentioning

confidence: 99%

“…Recent calculations of NLO QCD and EW corrections to important SM processes obtained in these frameworks include the production of a Higgs boson with a pair of on-shell [41] or off-shell top quarks [42], of tt plus jets [43], of EW vector bosons with jets [44,45,46] or photons [47], of diphotons plus jets [48], of a pair of off-shell EW bosons [49], of W W W [50], and of four on-shell top-quarks or of top pairs with a W boson [51]. NLOX, the program described in this article, is a new program for the automated computation of one-loop QCD and EW corrections in the Standard Model, which has recently been used in the computation of QCD and EW corrections to Z + b-jet production [52,53], and further partook in a technical comparison of tools for the automation of NLO EW calculations [54]. A non-public predecessor of NLOX has been available in the past, to calculate one-loop QCD corrections to selected processes [55,56].…”

Section: Introductionmentioning

confidence: 99%

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NLOX, a one-loop provider for Standard Model processes

Honeywell

Quackenbush

Reina

et al. 2020

Computer Physics Communications

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NLOX is a computer program for calculations in high-energy particle physics. It provides fully renormalized scattering matrix elements in the Standard Model of particle physics, up to one-loop accuracy for all possible coupling-power combinations in the strong and electroweak couplings, and for processes with up to six external particles. PROGRAM SUMMARYProgram Title: NLOX Licensing provisions: CC BY NC 3.0 Programming language: C++. Fortran interface available, and Fortran compiler required for dependencies. Required External Dependencies: QCDLoop 1.95, OneLOop 3.6 (available for download in utility tarball).NLOX provides fully renormalized QCD and EW one-loop corrections to SM processes at the squared-amplitude level, for all the possible QCD and EW mixed coupling-power combinations to a certain parton-level process up to one-loop accuracy, including the full mass dependence on initialand final-state particle masses. 5 Based on a Feynman-diagram approach, with optimized parsing and storing of recurrent building blocks,NLOX has been developed with the intent of providing oneloop QCD and EW corrections in the SM, while maintaining the flexibility to be further extended.The generation and evaluation of one-loop QCD and EW corrections of a large variety of 2 → 3 and 2 → 4 SM processes has been thoroughly tested and, with this paper, we are releasing a description of the code functionalities, archives of pre-generated process code, and the core code to evaluate and interface to the pre-generated process code.The conventions used in building renormalized one-loop QCD and EW amplitudes with NLOX are summarized in Sec. 2, while the NLOX workflow and code generation is briefly illustrated in Sec. 3. The TRed tensor-reduction library, an essential part of the NLOX package, is described in Sec. 4. Sec. 5 provides some practical instructions on how to download, install, and use the current public version of NLOX. Finally, in Sec. 6 we report benchmark results for selected processes. A brief summary is provided in Sec. 7. In the two appendices we collect more details about renormalization and tensor reduction in NLOX.

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“…This result makes it not only possible, but also advisableowing to the better perturbative description of the differential observables involving the heavy quark(s) -to employ the 4FS for the exclusive description of these processes. This has been shown explicitly to be the case in single-top production [3,4], bbH [5][6][7][8][9][10][11][12][13][14][15][16] and bbZ/γ production [16][17][18][19][20][21][22][23], and also for processes predicted by extensions of the Standard Model (SM), such as heavy charged Higgs boson production in a two-Higgs doublet model or in supersymmetry [24][25][26][27][28][29][30][31][32][33][34]. On the other hand, the calculations of the total rates in the 5FS display a faster perturbative convergence and exhibit a smaller scale uncertainty associated with missing higher orders.…”

Section: Introductionmentioning

confidence: 99%

A fragmentation-based study of heavy quark production

Ridolfi

Ubiali

Zaro

2020

J. High Energ. Phys.

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Processes involving heavy quarks are a crucial component of the LHC physics program, both by themselves and as backgrounds for Higgs physics and new physics searches. In this work, we critically reconsider the validity of the widely-adopted approximation in which heavy quarks are generated at the matrix-element level, with special emphasis on the impact of the collinear logarithms associated with final-state heavy quark and gluon splittings. Our study, based on a perturbative fragmentation-function approach, explicitly shows that neglecting the resummation of collinear logarithms may yield inaccurate predictions, in particular when observables exclusive in the heavy quark degrees of freedom are considered. Our findings motivate the use of schemes which encompass the resummation of final-state collinear logarithms.

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Electroweak and QCD corrections to Z -boson production with one b jet in a massive five-flavor scheme

Cited by 17 publications

References 91 publications

Fitting the b-quark PDF as a massive-b scheme: Higgs production in bottom fusion

Fitting the b-quark PDF as a massive-b scheme: Higgs production in bottom fusion

NLOX, a one-loop provider for Standard Model processes

A fragmentation-based study of heavy quark production

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