We present a first-principles lattice QCD+QED calculation at physical pion mass of the leading-order hadronic vacuum polarization contribution to the muon anomalous magnetic moment. The total ...contribution of up, down, strange, and charm quarks including QED and strong isospin breaking effects is a_{μ}^{HVP LO}=715.4(18.7)×10^{-10}. By supplementing lattice data for very short and long distances with R-ratio data, we significantly improve the precision to a_{μ}^{HVP LO}=692.5(2.7)×10^{-10}. This is the currently most precise determination of a_{μ}^{HVP LO}.
In this paper, we discuss how windows in Euclidean time can be used to isolate the origin of potential conflicts between evaluations of the hadronic-vacuum-polarization (HVP) contribution to the ...anomalous magnetic moment of the muon in lattice QCD and from e+e−→hadrons cross-section data. We provide phenomenological comparison numbers evaluated from e+e−→hadrons data for the window quantities most commonly studied in lattice QCD, complete with the correlations among them. We discuss and evaluate modifications of window parameters that could be useful in dissecting the energy dependence of tensions in the HVP integral and emphasize that further optimizations require a precise knowledge of the full covariance matrix in lattice-QCD calculations as well.
We report the first lattice QCD calculation of the hadronic vacuum polarization (HVP) disconnected contribution to the muon anomalous magnetic moment at physical pion mass. The calculation uses a ...refined noise-reduction technique that enables the control of statistical uncertainties at the desired level with modest computational effort. Measurements were performed on the 48^{3}×96 physical-pion-mass lattice generated by the RBC and UKQCD Collaborations. We find the leading-order hadronic vacuum polarization a_{μ}^{HVP(LO)disc}=-9.6(3.3)(2.3)×10^{-10}, where the first error is statistical and the second systematic.
We report the first lattice QCD calculation of the complex kaon decay amplitude A_{0} with physical kinematics, using a 32³×64 lattice volume and a single lattice spacing a, with 1/a=1.3784(68) GeV. ...We find Re(A_{0})=4.66(1.00)(1.26)×10(-7) GeV and Im(A_{0})=-1.90(1.23)(1.08)×10(-11) GeV, where the first error is statistical and the second systematic. The first value is in approximate agreement with the experimental result: Re(A_{0})=3.3201(18)×10(-7) GeV, while the second can be used to compute the direct CP-violating ratio Re(ϵ^{'}/ϵ)=1.38(5.15)(4.59)×10^{-4}, which is 2.1σ below the experimental value 16.6(2.3)×10(-4). The real part of A_{0} is CP conserving and serves as a test of our method while the result for Re(ϵ^{'}/ϵ) provides a new test of the standard model theory of CP violation, one which can be made more accurate with increasing computer capability.
A
bstract
We calculate the strong isospin breaking and QED corrections to meson masses and the hadronic vacuum polarization in an exploratory study on a 64 × 24
3
lattice with an inverse lattice ...spacing of
a
−1
= 1
.
78 GeV and an isospin symmetric pion mass of
m
π
= 340 MeV. We include QED in an electro-quenched setup using two different methods, a stochastic and a perturbative approach. We find that the electromagnetic correction to the leading hadronic contribution to the anomalous magnetic moment of the muon is smaller than 1% for the up quark and 0
.
1% for the strange quark, although it should be noted that this is obtained using unphysical light quark masses. In addition to the results themselves, we compare the precision which can be reached for the same computational cost using each method. Such a comparison is also made for the meson electromagnetic mass-splittings.
We present a lattice QCD calculation of the ΔI = 1/2, K → π π decay amplitude A 0 and ϵ ′, the measure of direct C P violation in K → π π decay, improving our 2015 calculation 1 of these quantities. ...Both calculations were performed with physical kinematics on a 323 × 64 lattice with an inverse lattice spacing of a−1 = 1.3784(68) GeV . However, the current calculation includes nearly 4 times the statistics and numerous technical improvements allowing us to more reliably isolate the π π ground state and more accurately relate the lattice operators to those defined in the standard model. We find Re(A0) = 2.99(0.32)(0.59) × 10−7 GeV and Im(A0) = − 6.98(0.62)(1.44) × 10−11 GeV, where the errors are statistical and systematic, respectively. The former agrees well with the experimental result Re(A0) = 3.3201(18) × 10−7 GeV . These results for A0 can be combined with our earlier lattice calculation of A2 2 to obtain Re(ϵ′/ϵ) = 21.7(2.6)(6.2)(5.0) × 10−4, where the third error represents omitted isospin breaking effects, and Re(A0) / Re(A2) = 19.9(2.3)(4.4). The first agrees well with the experimental result of Re(ϵ′/ϵ) = 16.6(2.3) × 10−4. A comparison of the second with the observed ratio Re(A0) / Re(A2) = 22.45(6), demonstrates the standard model origin of this " ΔI = 1/2 rule" enhancement.
We present results for several light hadronic quantities (f sub(pi), f sub(K), B sub(K), m sub(ud), m sub(s), t super(1/2) sub(0), w sub(0)) obtained from simulations of 2+1 flavor domain wall ...lattice QCD with large physical volumes and nearly physical pion masses at two lattice spacings. We perform a short, O(3)%, extrapolation in pion mass to the physical values by combining our new data in a simultaneous chiral/continuum "global fit" with a number of other ensembles with heavier pion masses. We use the physical values of m sub(pi), m sub(K) and m sub(Omega) to determine the two quark masses and the scale-all other quantities are outputs from our simulations. We obtain results with subpercent statistical errors and negligible chiral and finite-volume systematics for these light hadronic quantities, including f sub(pi)=130.2(9)MeV; f sub(K)=155.5(8)MeV; the average up/down quark mass and strange quark mass in the MS scheme at 3 GeV, 2.997(49) and 81.64(1.17) MeV respectively; and the neutral kaon mixing parameter, BK, in the renormalization group invariant scheme, 0.750(15) and the MS scheme at 3 GeV, 0.530(11).
The El Niño Southern Oscillation (ENSO) is a major driver of global hydro‐climatic variability, with well‐known effects on floods, droughts, and coupled human‐natural systems. Its impact on urban ...settlements depends on both level of exposure and preparedness; two factors that are responsible for severe cuts on millions of people in developing countries, where urban water supply relies almost entirely on rainfall‐dependent sources. To understand whether information on the ENSO state could help mitigate the effects of droughts, we use Metro Manila's water supply system as exemplifying case study, for which we design “traditional” and adaptive management policies. The former are based on information typically available to operators, such as reservoir storage; the latter complement such information with the Oceanic Niño Index (ONI)—an indicator used for monitoring El Niño and La Niña state. Results obtained by comparing the policy performance on a large set of stochastic streamflow and ONI replicates show that ENSO‐informed policies are more robust, meaning that they attain a minimum performance level across a broader set of replicates. We show that the primary cause of this behavior is the information on the ENSO state. To further quantify the value of the ONI, we then compare the performance of a representative ENSO‐informed policy and the system's current operating rules on the period 1968–2014. The comparison shows that the severe water supply restrictions caused by the existing management system could have been partially avoided through a sequence of smaller restrictions implemented at the onset of the main El Niño events.
Key Points
A computational framework to assess ENSO impact on urban water supply
ENSO‐informed operating policies increase system's robustness
Information on ENSO could reduce regrets in the present operations
A
bstract
We present results for the leading hadronic contribution to the muon anomalous magnetic moment due to strange quark-connected vacuum polarisation effects. Simulations were performed using ...RBC-UKQCD’s
N
f
= 2 + 1 domain wall fermion ensembles with physical light sea quark masses at two lattice spacings. We consider a large number of analysis scenarios in order to obtain solid estimates for residual systematic effects. Our final result in the continuum limit is
a
μ
(2)had,
s
= 53.1(9)(
− 3
+ 1
) × 10
− 10
.
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