Predictions for the Top-Quark Forward-Backward Asymmetry at High Invariant Pair Mass Using the Principle of Maximum Conformality

Abstract

The D0 collaboration at FermiLab has recently measured the top-quark pair forward-backward asymmetry in $\bar{p}p\to t\bar{t}X$ reactions as a function of the $t\bar{t}$ invariant mass $M_{t\bar{t}}$. The D0 result for $A_{\mathrm{FB}}(M_{t\bar{t}}>650\mathrm{GeV})$ is smaller than $A_{\mathrm{FB}}(M_{t\bar{t}})$ obtained for small values of $M_{t\bar{t}}$, which may indicate an "increasing-decreasing" behavior for $A_{\mathrm{FB}}(M_{t\bar{t}}>M_{\mathrm{cut}})$. This behavior is not explained using conventional renormalization scale-setting, even by a next-to-next-to-leading order (N${}^2$LO) QCD calculation -- one predicts a monotonically increasing behavior. In the conventional scale-setting method, one simply guesses a single renormalization scale ${\mu }_r$ for the argument of the QCD running coupling and then varies it over an arbitrary range. However, the conventional method has inherent difficulties. ...... In contrast, if one fixes the scale using the Principle of Maximum Conformality (PMC), the resulting pQCD predictions are renormalization-scheme independent since all of the scheme-dependent $\{{\beta }_i\}$-terms in the QCD perturbative series are resummed into the QCD running couplings at each order. ...... In this paper we show that if one applies the PMC to determine the top versus anti-top quark forward-backward asymmetry by properly using the pQCD predictions up to N${}^2$LO level, one obtains the predictions without renormalization scheme or scale ambiguities. ...... In addition, the PMC prediction for $A_{\mathrm{FB}}(M_{t\bar{t}}>M_{\mathrm{cut}})$ shows an "increasing-decreasing" behavior for increasing values of $M_{\mathrm{cut}}$ which is not observed in the NLO and N${}^2$LO predictions for $A_{\mathrm{FB}}(M_{t\bar{t}}>M_{\mathrm{cut}})$ with conventional scale-setting. This behavior could be tested by the future more precise measurements at the LHC.

7 pages, 2 figures. Revised version to be published in Phys.Rev.D

References in corpus (16)

• Implications of CTEQ global analysis for collider observables
• -- HATHOR -- HAdronic Top and Heavy quarks crOss section calculatoR
• First measurement of the forward-backward charge asymmetry in top quark pair production
• Eliminating the Renormalization Scale Ambiguity for Top-Pair Production Using the Principle of Maximum Conformality
• Measurement of the forward-backward asymmetry in top quark-antiquark production in ppbar collisions using the lepton+jets channel
• Self-Consistency Requirements of the Renormalization Group for Setting the Renormalization Scale
• Application of the Principle of Maximum Conformality to the Top-Quark Forward-Backward Asymmetry at the Tevatron
• Measurement of the top quark pair production cross section in the lepton+jets channel in proton-antiproton collisions at $\sqrt{s}$=1.96 TeV
• First Measurement of the Ratio sigma_(t-tbar) / sigma_(Z/γ*->ll) and Precise Extraction of the t-tbar Cross Section
• Asymmetries in top quark pair production at hadron colliders
• The top quark forward-backward asymmetry at approximate N${}^3$LO
• Degeneracy Relations in QCD and the Equivalence of Two Systematic All-Orders Methods for Setting the Renormalization Scale
• Application of the Principle of Maximum Conformality to the Top-Quark Charge Asymmetry at the LHC
• Simultaneous measurement of forward-backward asymmetry and top polarization in dilepton final states from $t\bar{t}$ production at the Tevatron
• Reanalysis of the Higher Order Perturbative QCD corrections to Hadronic $Z$ Decays using the Principle of Maximum Conformality
• Renormalization group improved pQCD prediction for ${\rm Y}(1S)$ leptonic decay

Cited by in corpus (10)

• The QCD Running Coupling
• Meson/Baryon/Tetraquark Supersymmetry from Superconformal Algebra and Light-Front Holography
• The Importance of Proper Renormalization Scale-Setting for Testing QCD at Colliders
• Ambiguities of the principle of maximum conformality procedure for hadron collider processes
• A precise determination of the top-quark pole mass
• Application of the Principle of Maximum Conformality to the Hadroproduction of the Higgs Boson at the LHC
• Revisiting the Bottom Quark Forward-Backward Asymmetry $A_{\mathrm{FB}}$ in Electron-Positron Collisions
• Reanalysis of the top-quark pair hadroproduction and a precise determination of the top-quark pole mass at the LHC
• Revisiting the top-quark pair production at future $e^{+}{e}^{-}$ colliders
• The Higgs-Boson Decay $H\to gg$ to Order ${\alpha }_s^5$ under the mMOM-Scheme