scholarly journals Precision studies for Drell–Yan processes at NNLO

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
S. Alekhin ◽  
A. Kardos ◽  
S. Moch ◽  
Z. Trócsányi
Keyword(s):  
Detailed Comparison ◽  
Leading Order ◽  
Order Accuracy ◽  
Power Corrections ◽  
Fixed Order ◽  
Computer Codes ◽  
Tevatron Colliders

AbstractWe present a detailed comparison of the fixed-order predictions computed by four publicly available computer codes for Drell–Yan processes at the LHC and Tevatron colliders. We point out that while there is agreement among the predictions at the next-to-leading order accuracy, the predictions at the next-to-next-to-leading order (NNLO) differ, whose extent depends on the observable. The sizes of the differences in general are at least similar, sometimes larger than the sizes of the NNLO corrections themselves. We demonstrate that the neglected power corrections by the codes that use global slicing methods for the regularization of double real emissions can be the source of the differences. Depending on the fiducial cuts, those power corrections become linear, hence enhanced as compared to quadratic ones that are considered standard.

QCD at Fixed Order: Processes

2018 ◽  
Author(s):  
John Campbell ◽  
Joey Huston ◽  
Frank Krauss
Keyword(s):  
Hadron Collider ◽  
Detailed Comparison ◽  
Theoretical Description ◽  
Higgs Bosons ◽  
Final States ◽  
Collider Physics ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Fixed Order ◽  
The Subject

At the core of any theoretical description of hadron collider physics is a fixed-order perturbative treatment of a hard scattering process. This chapter is devoted to a survey of fixed-order predictions for a wide range of Standard Model processes. These range from high cross-section processes such as jet production to much more elusive reactions, such as the production of Higgs bosons. Process by process, these sections illustrate how the techniques developed in Chapter 3 are applied to more complex final states and provide a summary of the fixed-order state-of-the-art. In each case, key theoretical predictions and ideas are identified that will be the subject of a detailed comparison with data in Chapters 8 and 9.

scholarly journals Lattice calculation of the hadronic leading order contribution to the muon g − 2

2020 ◽  
Vol 234 ◽  
pp. 01016
Author(s):  
Hartmut Wittig ◽  
Antoine Gérardin ◽  
Marco Cè ◽  
Georg von Hippel ◽  
Ben Hörz ◽  
...  
Keyword(s):  
Standard Model Prediction ◽  
Detailed Comparison ◽  
New Physics ◽  
Current Status ◽  
Leading Order ◽  
Lattice Calculation ◽  
Muon Anomalous Magnetic Moment ◽  
The Standard Model ◽  
Vacuum Polarisation

The persistent discrepancy of about 3.5 standard deviations between the experimental measurement and the Standard Model prediction for the muon anomalous magnetic moment, aµ, is one of the most promising hints for the possible existence of new physics. Here we report on our lattice QCD calculation of the hadronic vacuum polarisation contribution $ a_\mu ^{{\rm{hvp}}} $, based on gauge ensembles with Nf = 2 + 1 flavours of O(a) improved Wilson quarks. We address the conceptual and numerical challenges that one encounters along the way to a sub-percent determination of the hadronic vacuum polarisation contribution. The current status of lattice calculations of $ a_\mu ^{{\rm{hvp}}} $ is presented by performing a detailed comparison with the results from other groups.

scholarly journals Automatic predictions in the Georgi-Machacek model at next-to-leading order accuracy

2016 ◽  
Vol 93 (3) ◽  
Author(s):  
Céline Degrande ◽  
Katy Hartling ◽  
Heather E. Logan ◽  
Andrea D. Peterson ◽  
Marco Zaro
Keyword(s):  
Leading Order ◽  
Order Accuracy

scholarly journals Z0-boson production in association with att¯pair at next-to-leading order accuracy with parton shower effects

2012 ◽  
Vol 85 (7) ◽  
Author(s):  
M. V. Garzelli ◽  
A. Kardos ◽  
C. G. Papadopoulos ◽  
Z. Trócsányi
Keyword(s):  
Parton Shower ◽  
Boson Production ◽  
Leading Order ◽  
Order Accuracy

scholarly journals Groomed jet mass as a direct probe of collinear parton dynamics

2020 ◽  
Vol 80 (9) ◽  
Author(s):  
Daniele Anderle ◽  
Mrinal Dasgupta ◽  
Basem Kamal El-Menoufi ◽  
Marco Guzzi ◽  
Jack Helliwell
Keyword(s):  
Mass Distribution ◽  
Leading Order ◽  
Order Calculation ◽  
Fixed Order ◽  
Collinear Limit

AbstractWe study the link between parton dynamics in the collinear limit and the logarithmically enhanced terms of the groomed jet mass distribution, for jets groomed with the modified mass-drop tagger (mMDT). While the leading-logarithmic (LL) result is linked to collinear evolution with leading-order splitting kernels, here we derive the NLL structure directly from triple-collinear splitting kernels. The calculation we present is a fixed-order calculation in the triple-collinear limit, independent of resummation ingredients and methods. It therefore constitutes a powerful cross-check of the NLL results previously derived using the SCET formalism and provides much of the insight needed for resummation within the traditional QCD approach.

scholarly journals Power corrections in a transverse-momentum cut for vector-boson production at NNLO: the qg-initiated real-virtual contribution

2021 ◽  
Vol 81 (2) ◽  
Author(s):  
Carlo Oleari ◽  
Marco Rocco
Keyword(s):  
Transverse Momentum ◽  
Cross Section ◽  
Cross Sections ◽  
Vector Boson ◽  
Analytic Form ◽  
Leading Order ◽  
Coupling Constant ◽  
Subtraction Method ◽  
Power Corrections ◽  
Interference Contribution

AbstractWe consider the production of a vector boson (Z, $$W^\pm $$ W ± or $$\gamma ^*$$ γ ∗ ) at next-to-next-to-leading order in the strong coupling constant $$\alpha _\mathrm{S}$$ α S . We impose a transverse-momentum cutoff, $$q_{\mathrm{T}}^{\mathrm{cut}}$$ q T cut , on the vector boson produced in the qg-initiated channel. We then compute the power corrections in the cutoff, up to the second power, of the real-virtual interference contribution to the cumulative cross section at order $$\alpha _\mathrm{S}^2$$ α S 2 . Other terms with the same kinematics, originating from the subtraction method applied to the double-real contribution, have been also considered. The knowledge of such power corrections is a required ingredient in order to reduce the dependence on the transverse-momentum cutoff of the QCD cross sections at next-to-next-to-leading order, when the $$q_{\mathrm{T}}$$ q T -subtraction method is applied. In addition, the study of the dependence of the cross section on $$q_{\mathrm{T}}^{\mathrm{cut}}$$ q T cut allows as well for an understanding of its behaviour in the small transverse-momentum limit, giving hints on the structure at all orders in $$\alpha _\mathrm{S}$$ α S and on the identification of universal patterns. Our result are presented in an analytic form, using the process-independent procedure described in a previous paper for the calculation of the all-order power corrections in $$q_{\mathrm{T}}^{\mathrm{cut}}$$ q T cut .

scholarly journals Decoupling of charm beyond leading order

2018 ◽  
Vol 175 ◽  
pp. 10001 ◽  
Author(s):  
Francesco Knechtli ◽  
Tomasz Korzec ◽  
Björn Leder ◽  
Graham Moir
Keyword(s):  
Quark Mass ◽  
Charm Quark ◽  
Direct Access ◽  
Effective Theory ◽  
Leading Order ◽  
Charm Quarks ◽  
Charm Quark Mass ◽  
Power Corrections ◽  
Low Energies ◽  
Pure Gauge Theory

We study the effective theory of decoupling of a charm quark at low energies. We do this by simulating a model, QCD with two mass-degenerate charm quarks. At leading order the effective theory is a pure gauge theory. By computing ratios of hadronic scales we have direct access to the power corrections in the effective theory. We show that these corrections follow the expected leading behavior, which is quadratic in the inverse charm quark mass.

scholarly journals Signature of same-sign top pair production mediated by a nonuniversalZ′with QCD next-to-leading order accuracy at the LHC

2012 ◽  
Vol 86 (11) ◽  
Author(s):  
Bo Hua Li ◽  
Chong Sheng Li ◽  
Hai Tao Li ◽  
Yong Chuan Zhan ◽  
Yue Zhang ◽  
...  
Keyword(s):  
Pair Production ◽  
Leading Order ◽  
Order Accuracy ◽  
Top Pair Production
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