Improved Bhabha cross section at LEP and the number of light neutrino species

Abstract

In ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ collisions, the integrated luminosity is generally measured from the rate of low-angle Bhabha interactions ${\mathrm{e}}^{+}{\mathrm{e}}^{-}\to {\mathrm{e}}^{+}{\mathrm{e}}^{-}$. In the published LEP results, the inferred theoretical uncertainty of $\pm 0.061\%$ on the predicted rate is significantly larger than the reported experimental uncertainties. We present an updated and more accurate prediction of the Bhabha cross section in this letter, which is found to reduce the Bhabha cross section by about $0.048\%$, and its uncertainty to $\pm 0.037\%$. When accounted for, these changes modify the number of light neutrino species (and its accuracy), as determined from the LEP measurement of the hadronic cross section at the Z peak, to $N_{\nu }=2.9963\pm 0.0074$. The 20-years-old $2\sigma$ tension with the Standard Model is gone.

28 pages, 13 tables, 4 figures. Revision submitted to Physics Letters B. With respect to v1: 1) Hadronic vacuum polarization (VPhad) updated from FJ'17 to FJ'19, and compared to DHMZ'20 and KNT'20. 2) Leptonic vacuum polarization (VPlept) updated from LO to NNNLO. 3) Number of light neutrino species changed from 2.9975 to 2.9970 with new VPhad, and from 2.9970 to 2.9963 with new VPlept

References in corpus (1)

• Virtual Hadronic and Heavy-Fermion O(alpha^2) Corrections to Bhabha Scattering

Cited by in corpus (47)

• Modern and Future Colliders
• Probing Physics Beyond the Standard Model: Limits from BBN and the CMB Independently and Combined
• Low-energy phenomenology of scalar leptoquarks at one-loop accuracy
• A Search for Electron Neutrino Transitions to Sterile States in the BEST Experiment
• Global analysis of electroweak data in the Standard Model
• Revisiting Neutrino Self-Interaction Constraints from $Z$ and $\tau$ decays
• Event Generators for High-Energy Physics Experiments
• First-Generation New Physics in Simplified Models: From Low-Energy Parity Violation to the LHC
• Effective portals to heavy neutral leptons
• Global Fit of Modified Quark Couplings to EW Gauge Bosons and Vector-Like Quarks in Light of the Cabibbo Angle Anomaly
• $A_{FB}$ in the SMEFT: precision Z physics at the LHC
• Muon $g-2$ and CKM Unitarity in Extra Lepton Models
• EFT analysis of New Physics at COHERENT
• Dynamical Minimal Flavour Violating Inverse Seesaw
• Third-Family Quark-Lepton Unification and Electroweak Precision Tests
• Beta-decay implications for the W-boson mass anomaly
• From B-meson anomalies to Kaon physics with scalar leptoquarks
• A model for the Singlet-Triplet Leptoquarks
• $W$-Boson Mass, Electroweak Precision Tests and SMEFT
• New physics interpretation of $W$-boson mass anomaly
• Electroweak precision test of axion-like particles
• Anomalies in B mesons decays: A phenomenological approach
• Effective comparison of neutrino-mass models
• The muon g-2 anomaly confronts new physics in $e^{\pm }$ and ${\mu }^{\pm }$ final states scattering
• How large can the Light Quark Yukawa couplings be?
• Improved strong coupling determinations from hadronic decays of electroweak bosons at N${}^3$LO accuracy
• The Low-Scale Seesaw Solution to the $M_W$ and $(g-2{)}_{\mu }$ Anomalies
• Constraints on the dark sector from electroweak precision observables
• Effective field theory analysis of dark matter-standard model interactions with spin one mediators
• Higgs Squared
• Signal processing and spectral modeling for the BeEST experiment
• Light Sterile Neutrinos
• The Z lineshape challenge: ppm and keV measurements
• Probing the non-standard neutrino interactions using quantum statistics
• TASI 2020 Lectures on Precision Tests of the Standard Model
• Probing the mixing between sterile and tau neutrinos in the SHiP experiment
• New Physics contamination to precision luminosity measurements at future $e^{+}{e}^{-}$ colliders
• An EWPD SMEFT likelihood for the LHC -- and how to improve it with measurements of W and Z boson properties
• Circular and Linear ${\mathrm{e}}^{+}{\mathrm{e}}^{-}$ Colliders: Another Story of Complementarity
• Search for sterile neutrino with light gauge interactions: recasting collider, beam-dump, and neutrino telescope searches
• Round table on Standard Model Anomalies
• The Forward Physics Facility at the High-Luminosity LHC
• Dark Z-mediated dark matter with verifiable exotic scalars
• Standard and Non-Standard Aspects of Neutrino Physics
• Precision Theory of Electroweak Interactions
• New Physics Hints from Flavour
• On the implications of positive W mass shift