scholarly journals Tree-level splitting amplitudes for a gluon into four collinear partons

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Vittorio Del Duca ◽  
Claude Duhr ◽  
Rayan Haindl ◽  
Achilleas Lazopoulos ◽  
Martin Michel
Keyword(s):  
Scattering Amplitudes ◽  
Strong Coupling ◽  
Strong Coupling Constant ◽  
Tree Level ◽  
Leading Order ◽  
Coupling Constant ◽  
Level Splitting ◽  
Infrared Behaviour

Abstract We compute in conventional dimensional regularisation the tree-level splitting amplitudes for a gluon parent which splits into four collinear partons. This is part of the universal infrared behaviour of the QCD scattering amplitudes at next-to-next-to-next-to-leading order (N3LO) in the strong coupling constant. Combined with our earlier results for a quark parent, this completes the set of tree-level splitting amplitudes required at this order. We also study iterated collinear limits where a subset of the four collinear partons become themselves collinear.

scholarly journals Precise determination of αS( $ m_{Z^0 } $ ) from a global fit of energy-energy correlations to NNLO+NNLL predictions

2019 ◽  
Vol 206 ◽  
pp. 05002
Author(s):  
A. Kardos ◽  
S. Kluth ◽  
G. Somogyi ◽  
Z. Tulipánt ◽  
A. Verbytskyi
Keyword(s):  
Strong Coupling ◽  
Precise Determination ◽  
Strong Coupling Constant ◽  
Final States ◽  
Leading Order ◽  
Coupling Constant ◽  
Global Fit ◽  
Hadronic Final States

We present a determination of the strong coupling constant αS( $ m_{Z^0 } $ ) using a global fit of theory predictions in next-to-next-next-leading-order (NNLO) combined with resummed predictions at the next-to-next-leading-log level (NNLL) [bibrR11]. The predictions are compared to distributions of energy-energy correlations measured in e+e−annihilation to hadronic final states by experiments at the e+e−colliders LEP, PETRA, TRISTAN and PEP. The predictions are corrected for hadronisation effects using the modern generator programs Sherpa 2.2.4 and Herwig 7.1.1.

scholarly journals Erratum to: Determination of the strong coupling constant $${{\varvec{\alpha _{\mathrm{s}} (m_{\mathrm{Z}})}}}$$ in next-to-next-to-leading order QCD using H1 jet cross section measurements

2021 ◽  
Vol 81 (8) ◽  
Author(s):  
◽  
V. Andreev ◽  
A. Baghdasaryan ◽  
K. Begzsuren ◽  
A. Belousov ◽  
...  
Keyword(s):  
Strong Coupling ◽  
Cross Section ◽  
Distribution Functions ◽  
Strong Coupling Constant ◽  
Leading Order ◽  
Coupling Constant ◽  
Parton Distribution Functions ◽  
Section Data ◽  
Dijet Data

AbstractThe determination of the strong coupling constant $$\alpha _{\mathrm{s}} (m_{\mathrm{Z}})$$ α s ( m Z ) from H1 inclusive and dijet cross section data [1] exploits perturbative QCD predictions in next-to-next-to-leading order (NNLO) [2–4]. An implementation error in the NNLO predictions was found [4] which changes the numerical values of the predictions and the resulting values of the fits. Using the corrected NNLO predictions together with inclusive jet and dijet data, the strong coupling constant is determined to be $$\alpha _{\mathrm{s}} (m_{\mathrm{Z}}) =0.1166\,(19)_{\mathrm{exp}}\,(24)_{\mathrm{th}}$$ α s ( m Z ) = 0.1166 ( 19 ) exp ( 24 ) th . Complementarily, $$\alpha _{\mathrm{s}} (m_{\mathrm{Z}})$$ α s ( m Z ) is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value $$\alpha _{\mathrm{s}} (m_{\mathrm{Z}}) =0.1147\,(25)_{\mathrm{tot}}$$ α s ( m Z ) = 0.1147 ( 25 ) tot obtained is consistent with the determination from jet data alone. Corrected figures and numerical results are provided and the discussion is adapted accordingly.

scholarly journals QCD EVOLUTION OF NAIVE-TIME-REVERSAL-ODD QUARK-GLUON CORRELATION FUNCTIONS

2012 ◽  
Vol 20 ◽  
pp. 118-128 ◽  
Author(s):  
ZHONG-BO KANG ◽  
JIAN-WEI QIU
Keyword(s):  
Transverse Momentum ◽  
Strong Coupling ◽  
Time Reversal ◽  
Correlation Functions ◽  
Scale Dependence ◽  
Strong Coupling Constant ◽  
Leading Order ◽  
Coupling Constant ◽  
Mulders Function

In this talk, we examine the existing calculations of QCD evolution kernels for the scale dependence of two sets of twist-3 quark-gluon correlation functions, Tq,F(x, x) and [Formula: see text], which are the first transverse-momentum-moment of the naive-time-reversal-odd Sivers and Boer-Mulders function, respectively. The evolution kernels at the leading order in strong coupling constant αs were derived by several groups with apparent differences. We identify the sources of discrepancies and are able to reconcile the results from various groups.

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