scholarly journals Inclusive gluon production in pion-proton collisions and the principle of maximum conformality renormalization scale

2014 ◽  
Vol 89 (1) ◽  
Author(s):  
A. I. Ahmadov ◽  
C. Aydin ◽  
O. Uzun
Keyword(s):  
Renormalization Scale ◽  
Proton Collisions ◽  
Gluon Production ◽  
Principle Of Maximum

scholarly journals The renormalization scale problem and novel perspectives for QCD

2015 ◽  
Vol 39 ◽  
pp. 1560108
Author(s):  
Stanley J. Brodsky
Keyword(s):  
Renormalization Scale ◽  
High Transverse Momentum ◽  
Proton Proton ◽  
Direct Production ◽  
Proton Collisions ◽  
Qcd Factorization ◽  
Quarkonium Production ◽  
Proton Proton Collisions ◽  
Principle Of Maximum

I discuss a number of novel tests of QCD, measurements which can illuminate fundamental features of hadron physics. These include the origin of the “ridge” in proton-proton collisions; the production of the Higgs at high [Formula: see text]; the role of digluon-initiated processes for quarkonium production; flavor-dependent anti-shadowing; the effect of nuclear shadowing on QCD sum rules; direct production of hadrons at high transverse momentum; and leading-twist lensing corrections; and the breakdown of perturbative QCD factorization. I also review the “Principle of Maximum Conformalit” (PMC) which systematically sets the renormalization scale order-by-order in pQCD, independent of the choice of renormalization scheme, thus eliminating an unnecessary theoretical uncertainty.

scholarly journals Higher-twist mechanism and inclusive gluon production in pion–proton collisions

2015 ◽  
Vol 30 (36) ◽  
pp. 1550217
Author(s):  
A. I. Ahmadov ◽  
C. Aydin ◽  
R. Myrzakulov ◽  
O. Uzun
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Production Cross Section ◽  
Production Cross ◽  
Feynman Diagrams ◽  
Proton Collisions ◽  
Running Coupling ◽  
Gluon Production ◽  
Coupling Approach ◽  
Holographic Qcd

We calculate the contribution of the higher-twist Feynman diagrams to the large-[Formula: see text] inclusive gluon production cross-section in [Formula: see text] collisions in case of the running coupling and frozen coupling approaches within perturbative and holographic QCD. The structure of infrared renormalon singularities of the higher-twist subprocess cross-section is obtained and the resummed higher-twist cross-sections (Borel sum) with the ones obtained in the framework of the frozen coupling approach and leading-twist cross-section are compared and analyzed.

scholarly journals Z-boson hadronic decay width up to $${{\mathcal {O}}}(\alpha _s^4)$$-order QCD corrections using the single-scale approach of the principle of maximum conformality

2021 ◽  
Vol 81 (4) ◽  
Author(s):  
Xu-Dong Huang ◽  
Xing-Gang Wu ◽  
Xu-Chang Zheng ◽  
Qing Yu ◽  
Sheng-Quan Wang ◽  
...  
Keyword(s):  
Quantum Chromodynamics ◽  
Perturbative Qcd ◽  
Decay Width ◽  
Z Boson ◽  
Hadronic Decay ◽  
Experimental Measurements ◽  
Renormalization Scale ◽  
Single Scale ◽  
Global Fit ◽  
Principle Of Maximum

AbstractIn the paper, we study the properties of the Z-boson hadronic decay width by using the $$\mathcal {O}(\alpha _s^4)$$ O ( α s 4 ) -order quantum chromodynamics (QCD) corrections with the help of the principle of maximum conformality (PMC). By using the PMC single-scale approach, we obtain an accurate renormalization scale-and-scheme independent perturbative QCD (pQCD) correction for the Z-boson hadronic decay width, which is independent to any choice of renormalization scale. After applying the PMC, a more convergent pQCD series has been obtained; and the contributions from the unknown $$\mathcal {O}(\alpha _s^5)$$ O ( α s 5 ) -order terms are highly suppressed, e.g. conservatively, we have $$\Delta \Gamma _{\mathrm{Z}}^{\mathrm{had}}|^{{{\mathcal {O}}}(\alpha _s^5)}_{\mathrm{PMC}}\simeq \pm 0.004$$ Δ Γ Z had | PMC O ( α s 5 ) ≃ ± 0.004 MeV. In combination with the known electro-weak (EW) corrections, QED corrections, EW–QCD mixed corrections, and QED–QCD mixed corrections, our final prediction of the hadronic Z decay width is $$\Gamma _{\mathrm{Z}}^{\mathrm{had}}=1744.439^{+1.390}_{-1.433}$$ Γ Z had = 1744 . 439 - 1.433 + 1.390 MeV, which agrees with the PDG global fit of experimental measurements, $$1744.4\pm 2.0$$ 1744.4 ± 2.0 MeV.

scholarly journals Revisiting the bottom quark forward–backward asymmetry $$A_\mathrm{{FB}}$$ in electron–positron collisions

2020 ◽  
Vol 80 (7) ◽  
Author(s):  
Sheng-Quan Wang ◽  
Rui-Qing Meng ◽  
Xing-Gang Wu ◽  
Long Chen ◽  
Jian-Ming Shen
Keyword(s):  
Experimental Determination ◽  
Bottom Quark ◽  
Model Fit ◽  
Renormalization Scale ◽  
Leading Order ◽  
Electron Positron ◽  
Order Of Magnitude ◽  
Positron Collisions ◽  
Reasonable Behavior ◽  
Principle Of Maximum

Abstract The bottom quark forward–backward asymmetry $$A_\mathrm{{FB}}$$AFB is a key observable in electron–positron collisions at the $$Z^{0}$$Z0 peak. In this paper, we employ the Principle of Maximum Conformality (PMC) to fix the $$\alpha _s$$αs-running behavior of the next-to-next-to-leading order QCD corrections to $$A_\mathrm{{FB}}$$AFB. The resulting PMC scale for this $$A_\mathrm{{FB}}$$AFB is an order of magnitude smaller than the conventional choice $$\mu _r=M_Z$$μr=MZ. This scale has the physically reasonable behavior and reflects the virtuality of its QCD dynamics, which is independent to the choice of renormalization scale. Our analyses show that the effective momentum flow for the bottom quark forward–backward asymmetry should be $$\mu _r\ll M_Z$$μr≪MZ other than the conventionally suggested $$\mu _r=M_Z$$μr=MZ. Moreover, the convergence of perturbative QCD series for $$A_\mathrm{{FB}}$$AFB is greatly improved using the PMC. Our prediction for the bare bottom quark forward–backward asymmetry is refined to be $$A^{0,b}_\mathrm{FB}=0.1004\pm 0.0016$$AFB0,b=0.1004±0.0016, which diminishes the well known tension between the experimental determination for this (pseudo) observable and the respective Standard Model fit to $$2.1\sigma $$2.1σ.

scholarly journals Higher-Twist Mechanism and Inclusive Gluon Production in Pion-Proton Collisions

2016 ◽  
Vol 670 ◽  
pp. 012001
Author(s):  
A. I. Ahmadov ◽  
C. Aydin ◽  
R. Myrzakulov ◽  
O. Uzun
Keyword(s):  
Proton Collisions ◽  
Gluon Production
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