Finite-width effects on threshold corrections to squark and gluino production

Falgari, Pietro; Schwinn, Christian; Wever, Christopher

doi:10.1007/jhep01(2013)085

Cited by 22 publications

(19 citation statements)

References 67 publications

(129 reference statements)

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“…Corresponding results for top squarks have been obtained as well [16,[21][22][23][24][25][26][27][28]. Complementary work to this improvement of total cross sections by higher-order QCD corrections is provided by the computation of electroweak contributions [29][30][31][32][33][34][35][36], the automation of NLO calculations in the MSSM [37,38], the matching of NLO corrections to a parton shower [39][40][41], the calculation of NLO corrections to squark production and decay [40,42,43] and the estimate of finite-width effects [44].…”

Section: Introductionmentioning

confidence: 89%

NNLL soft and Coulomb resummation for squark and gluino production at the LHC

Beneke

Piclum

Schwinn

et al. 2016

J. High Energ. Phys.

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We present predictions for the total cross sections for pair production of squarks and gluinos at the LHC including a combined NNLL resummation of soft and Coulomb gluon effects. We derive all terms in the NNLO cross section that are enhanced near the production threshold, which include contributions from spin-dependent potentials and socalled annihilation corrections. The NNLL corrections at √ s = 13 TeV range from up to 20% for squark-squark production to 90% for gluino pair production relative to the NLO results and reduce the theoretical uncertainties of the perturbative calculation to the 10% level. Grid files with our numerical results are publicly available [1].

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Section: Introductionmentioning

confidence: 89%

NNLL soft and Coulomb resummation for squark and gluino production at the LHC

Beneke

Piclum

Schwinn

et al. 2016

J. High Energ. Phys.

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“…We also find that the corresponding Coulomb term is absent in the case of the charged B decay. We note that D + and τ − are sufficiently long-lived for the resummations to be valid [39]…”

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confidence: 99%

Soft-Photon Corrections to B¯→Dτ−ν
Boer
¹
,
Kitahara
²
,
Nišandžić
³

2018
Phys. Rev. Lett.

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We evaluate long-distance electromagnetic (QED) contributions toBrelative toB 0 → D þ μ −ν μ and B − → D 0 μ −ν μ , respectively, in the standard model. We point out that the QED corrections to the ratios RðD þ Þ and RðD 0 Þ are not negligible, contrary to the expectation that radiative corrections are almost canceled out in the ratio of the two branching fractions. The reason is that longdistance QED corrections depend on the masses and relative velocities of the daughter particles. We find that theoretical predictions for RðD þ Þ τ=μ and RðD 0 Þ τ=μ can be amplified by ∼4% and ∼3%, respectively, for the soft-photon energy cut in the range 20-40 MeV. DOI: 10.1103/PhysRevLett.120.261804 The semileptonic B meson decays that are at the elementary level induced by the b → clν l transitions provide a potentially interesting avenue for testing the standard model (SM) at low energies. In this respect, it turns out useful to construct the ratios RðHÞ, H ¼ D, D Ã between the branching fractions that involve τ leptons and those involving light leptons. These observables do not depend on the Cabibbo-Kobayashi-Maskawa matrix element V cb and are also theoretically cleaner due to the (partial) cancellation of the hadronic uncertainties parametrized by the corresponding form factors. The forthcoming Belle II experiment is expected to reduce the corresponding measurement uncertainties to the level of around 3% [1], comparable to the current theoretical uncertainties. This is also the typical size of electromagnetic (QED) effects, which we turn to study in this Letter, focusing on long-distance QED effects in RðDÞ.Short-distance electroweak (EW) contributions to branching fractions of semileptonic decays were evaluated to 1.3% [2-4], but since such corrections are lepton universal, they cancel in the ratio RðDÞ. The complete understanding of QED effects in meson decays is a nontrivial task due to the complicated interplay with QCD dynamics, e.g., structure-dependent contributions that probe the hadronic content [5][6][7]. In this Letter, we evaluate the lepton-massdependent soft-photon effects, which give rise to important corrections.We point out terms that distinguish the cases of the neutral and charged B decaysThe up-to-date average [2] of the lattice-QCD predictions [8,9] iswhich is consistent with previous evaluations involving different approaches (see [10][11][12][13][14] which combines electrons and muons for the decay into the light lepton and averages neutral and charged B decays. The averaged experimental result exceeds the SM expectation at the level of 2.2σ. Combined with current discrepancy with respect to the SM in RðD Ã Þ, these have been considered as a hint of physics beyond the SM.One should note that the measured results partially include soft photons using PHOTOS Monte Carlo generator [19,20] for the simulation of modifications of the kinematic variables induced by final-state photon radiations [21][22][23].

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“…The progress towards resummation at next-tonext-to-leading logarithmic (NNLL) accuracy and towards the corresponding LHC predictions has been reported in [43][44][45][46][47][48][49][50][51][52]. Finite width and bound state effects have been studied for squark and gluino production processes in [53][54][55][56][57][58]. Resummed calculations for sleptons and gauginos are also available at NLO+NLL accuracy [59][60][61].A potential source of theory uncertainty in these calculations arises from the fact that they are based on parton distribution functions (PDFs) extracted from experimental data using partonic cross-sections computed at fixed-order, NLO accuracy.…”

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confidence: 99%

NLO+NLL squark and gluino production cross sections with threshold-improved parton distributions

et al. 2016

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We present updated predictions for the cross sections for pair production of squarks and gluinos at the LHC Run II. First of all, we update the calculations based on NLO+NLL partonic cross sections by using the NNPDF3.0NLO global analysis. This study includes a full characterization of theoretical uncertainties from higher orders, PDFs and the strong coupling. Then we explore the implications for this calculation of the recent NNPDF3.0 PDFs with NLO+NLL threshold resummation. We find that the shift in the results induced by the threshold-improved PDFs is within the total theory uncertainty band of the calculation based on NLO PDFs. However, we also observe that the central values of the NLO+NLL cross sections are modified both in a qualitative and a quantitative way, illustrating the relevance and impact of using threshold-improved PDFs together with resummed partonic cross sections. The updated NLO+NLL cross sections based on NNPDF3.0NLO are publicly available in the NLL-fast format, and should be an important ingredient for the interpretation of the searches for supersymmetric particles at Run II.

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Finite-width effects on threshold corrections to squark and gluino production

Cited by 22 publications

References 67 publications

NNLL soft and Coulomb resummation for squark and gluino production at the LHC

NNLL soft and Coulomb resummation for squark and gluino production at the LHC

Soft-Photon Corrections to B¯→Dτ−ν
Boer
¹
,
Kitahara
²
,
Nišandžić
³

2018
Phys. Rev. Lett.

NLO+NLL squark and gluino production cross sections with threshold-improved parton distributions

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Finite-width effects on threshold corrections to squark and gluino production

Cited by 22 publications

References 67 publications

NNLL soft and Coulomb resummation for squark and gluino production at the LHC

NNLL soft and Coulomb resummation for squark and gluino production at the LHC

Soft-Photon Corrections to B¯→Dτ−νBoer1, Kitahara2, Nišandžić3 2018Phys. Rev. Lett.

NLO+NLL squark and gluino production cross sections with threshold-improved parton distributions

Contact Info

Product

Resources

About

Soft-Photon Corrections to B¯→Dτ−ν
Boer
¹
,
Kitahara
²
,
Nišandžić
³

2018
Phys. Rev. Lett.