scholarly journals Hadronic light-by-light contribution to $$(g-2)_\mu $$ from lattice QCD: a complete calculation

2021 ◽  
Vol 81 (7) ◽  
Author(s):  
En-Hung Chao ◽  
Renwick J. Hudspith ◽  
Antoine Gérardin ◽  
Jeremy R. Green ◽  
Harvey B. Meyer ◽  
...  
Keyword(s):  
Light Scattering ◽  
Lattice Qcd ◽  
Strange Quark ◽  
Systematic Errors ◽  
Point Function ◽  
Quark Sector ◽  
A Value ◽  
Complete Calculation ◽  
Scattering Contribution ◽  
Theory And Experiment

AbstractWe compute the hadronic light-by-light scattering contribution to the muon $$g-2$$ g - 2 from the up, down, and strange-quark sector directly using lattice QCD. Our calculation features evaluations of all possible Wick-contractions of the relevant hadronic four-point function and incorporates several different pion masses, volumes, and lattice-spacings. We obtain a value of $$a_\mu ^{\text {Hlbl}}= 106.8(15.9) \times 10^{-11}$$ a μ Hlbl = 106.8 ( 15.9 ) × 10 - 11 (adding statistical and systematic errors in quadrature), which is consistent with current phenomenological estimates and a previous lattice determination. It now appears conclusive that the hadronic light-by-light contribution cannot explain the current tension between theory and experiment for the muon $$g-2$$ g - 2 .

scholarly journals Hadronic light-by-light scattering in the muon g − 2

2019 ◽  
Vol 218 ◽  
pp. 01001
Author(s):  
Andreas Nyffeler
Keyword(s):  
Light Scattering ◽  
Lattice Qcd ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Current Status ◽  
Reliable Estimate ◽  
Model Calculations ◽  
Recent Developments ◽  
Model Independent ◽  
Scattering Contribution

We briefly review the current status of the hadronic light-by-light scattering contribution to the anomalous magnetic moment of the muon. Based on various model calculations in the literature, we obtain the estimate $ \mathop a\nolimits_\mu ^{HLbL} = (102 \pm 39) \times \mathop {10}\nolimits^{ - 11} $. Recent developments including more model-independent approaches using dispersion relations and lattice QCD, that could lead to a more reliable estimate, are also discussed.

scholarly journals Hadronic light-by-light scattering contribution to the muon g – 2 on the lattice

2018 ◽  
Vol 179 ◽  
pp. 01017 ◽  
Author(s):  
Nils Asmussen ◽  
Antoine Gérardin ◽  
Jeremy Green ◽  
Oleksii Gryniuk ◽  
Georg von Hippel ◽  
...  
Keyword(s):  
Light Scattering ◽  
Lattice Qcd ◽  
Cross Sections ◽  
Pion Pole ◽  
Lattice Calculation ◽  
Pole Contribution ◽  
Virtual Pion ◽  
Scattering Contribution ◽  
Space Approach ◽  
The Continuum

We briefly review several activities at Mainz related to hadronic light-by-light scattering (HLbL) using lattice QCD. First we present a position-space approach to the HLbL contribution in the muon g̅2, where we focus on exploratory studies of the pion-pole contribution in a simple model and the lepton loop in QED in the continuum and in infinite volume. The second part describes a lattice calculation of the double-virtual pion transition form factor Fπ0γ*γ* (q21; q21) in the spacelike region with photon virtualities up to 1.5 GeV2 which paves the way for a lattice calculation of the pion-pole contribution to HLbL. The third topic involves HLbL forward scattering amplitudes calculated in lattice QCD which can be described, using dispersion relations (HLbL sum rules), by γ*γ* → hadrons fusion cross sections and then compared with phenomenological models.

scholarly journals Archie's law – a reappraisal

Solid Earth ◽  
2016 ◽  
Vol 7 (4) ◽  
pp. 1157-1169 ◽  
Author(s):  
Paul W. J. Glover
Keyword(s):  
Systematic Errors ◽  
Apparent Paradox ◽  
Archie’S Law ◽  
A Value ◽  
The Difference ◽  
Reservoir Parameter ◽  
Parameter Values ◽  
Electrical Data ◽  
Extra Parameter ◽  
Better Than

Abstract. When scientists apply Archie's first law they often include an extra parameter a, which was introduced about 10 years after the equation's first publication by Winsauer et al. (1952), and which is sometimes called the “tortuosity” or “lithology” parameter. This parameter is not, however, theoretically justified. Paradoxically, the Winsauer et al. (1952) form of Archie's law often performs better than the original, more theoretically correct version. The difference in the cementation exponent calculated from these two forms of Archie's law is important, and can lead to a misestimation of reserves by at least 20 % for typical reservoir parameter values. We have examined the apparent paradox, and conclude that while the theoretical form of the law is correct, the data that we have been analysing with Archie's law have been in error. There are at least three types of systematic error that are present in most measurements: (i) a porosity error, (ii) a pore fluid salinity error, and (iii) a temperature error. Each of these systematic errors is sufficient to ensure that a non-unity value of the parameter a is required in order to fit the electrical data well. Fortunately, the inclusion of this parameter in the fit has compensated for the presence of the systematic errors in the electrical and porosity data, leading to a value of cementation exponent that is correct. The exceptions are those cementation exponents that have been calculated for individual core plugs. We make a number of recommendations for reducing the systematic errors that contribute to the problem and suggest that the value of the parameter a may now be used as an indication of data quality.

scholarly journals Hadronic light-by-light scattering amplitudes from lattice QCD versus dispersive sum rules

2018 ◽  
Vol 98 (7) ◽  
Author(s):  
Antoine Gérardin ◽  
Jeremy Green ◽  
Oleksii Gryniuk ◽  
Georg von Hippel ◽  
Harvey B. Meyer ◽  
...  
Keyword(s):  
Light Scattering ◽  
Scattering Amplitudes ◽  
Lattice Qcd ◽  
Sum Rules

scholarly journals Nucleon sigma term and strange quark content from lattice QCD with exact chiral symmetry

2008 ◽  
Vol 78 (5) ◽  
Author(s):  
H. Ohki ◽  
H. Fukaya ◽  
S. Hashimoto ◽  
T. Kaneko ◽  
H. Matsufuru ◽  
...  
Keyword(s):  
Lattice Qcd ◽  
Chiral Symmetry ◽  
Strange Quark ◽  
Sigma Term ◽  
Quark Content

scholarly journals A Note on Koide’s Doubly Special Parametrization of Quark Masses

Open Physics ◽  
2018 ◽  
Vol 16 (1) ◽  
pp. 427-429
Author(s):  
Piotr Żenczykowski
Keyword(s):  
Charged Lepton ◽  
Strange Quark ◽  
Scale Parameter ◽  
Low Energy ◽  
Quark Masses ◽  
Quark Sector ◽  
Energy Regime ◽  
Two Parameters

Abstract Three charged lepton masses may be expressed in terms of a Z3-symmetric parametrization relevant for the discussion of Koide’s formula. After disregarding the overall scale parameter, the observed pattern of lepton masses can be described extremely well if the remaining two parameters acquire the unexpectedly simple values of 1 and 2/9. We argue that an analogue of this doubly special feature of the parametrization can also be seen in the quark sector provided that the mass of the strange quark is taken to be around 160 MeV, as might be expected in the low-energy regime.

scholarly journals THE NUCLEON MASS AND PION-NUCLEON SIGMA TERM FROM A CHIRAL ANALYSIS OF Nf = 2 + 1 LATTICE QCD WORLD DATA

2014 ◽  
Vol 26 ◽  
pp. 1460089 ◽  
Author(s):  
L. ALVAREZ-RUSO ◽  
T. LEDWIG ◽  
M. J. VICENTE VACAS ◽  
J. MARTIN-CAMALICH
Keyword(s):  
Lattice Qcd ◽  
Degrees Of Freedom ◽  
Pion Mass ◽  
Nucleon Mass ◽  
A Value ◽  
Natural Size ◽  
Sigma Term ◽  
Pion Nucleon ◽  
Pion Mass Dependence ◽  
Energy Constants

Fits of the p4 covariant SU(2) baryon chiral perturbation theory to lattice QCD nucleon mass data from several collaborations for 2 and 2+1 flavors are presented. We consider contributions from explicit Δ(1232) degrees of freedom, finite volume and finite spacing corrections. We emphasize here on our Nf = 2 + 1 study. We obtain low-energy constants of natural size that are compatible with the rather linear pion-mass dependence of the nucleon mass observed in lattice QCD. We report a value of σπN = 41(5)(4) MeV in the 2 flavor case and σπN = 52(3)(8) MeV for 2+1 flavors.

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