Periodic Reporting for period 4 - SIMDAMA (Strong-interaction matter coupled to electroweak probes and dark matter candidates)
Période du rapport: 2022-10-01 au 2023-03-31
A decade after the discovery of the Higgs boson and with the
non-observation of particles beyond the Standard Model at the Large
Hadron Collider, several research avenues in particle physics are
being pursued in parallel. These include the search for dark matter
particles, the quest to complete the determination of neutrino
oscillation parameters and their absolute mass scale, as well as the
intensified search for deviations between Standard Model predictions
and experimental measurements of precision observables. While the
Standard Model of particle physics has been enormously successful at
predicting observables measured in collider experiments, it fails to
account for gravity, for neutrino oscillations and for dark matter,
which makes up for 27 percent of the energy in the universe.
Project SIMDAMA, based on the `lattice QCD' framework, aimed at
enabling a more stringent test of the Standard Model (SM),
contributing to narrowing down the list of dark-matter candidate
particles, and reducing uncertainties in neutrino detection. In all
cases, the complexity of the strong interaction is a bottleneck in
pursuing these research avenues. The strong-interaction physics is
addressed within SIMDAMA using the ab initio method of lattice
QCD. The method is numerically very demanding and requires massively
parallel computing resources.
As a conclusion of SIMDAMA, the scattering of light by light via
hadrons contribution in the muon g-2 cannot explain the existing
tension between its direct experimental measurement and the
theoretical prediction based on the SM. Neutrinos are more likely to
be scattered by protons at momentum transfers of typical hadronic
scale than previously thought; and the scattering of hypothetical
massive dark matter particles on nuclei via exchange of a Higgs
particle can now better be quantified. And the quark-gluon plasma
emits hard photons at a rate in line with weak-coupling predictions.
non-observation of particles beyond the Standard Model at the Large
Hadron Collider, several research avenues in particle physics are
being pursued in parallel. These include the search for dark matter
particles, the quest to complete the determination of neutrino
oscillation parameters and their absolute mass scale, as well as the
intensified search for deviations between Standard Model predictions
and experimental measurements of precision observables. While the
Standard Model of particle physics has been enormously successful at
predicting observables measured in collider experiments, it fails to
account for gravity, for neutrino oscillations and for dark matter,
which makes up for 27 percent of the energy in the universe.
Project SIMDAMA, based on the `lattice QCD' framework, aimed at
enabling a more stringent test of the Standard Model (SM),
contributing to narrowing down the list of dark-matter candidate
particles, and reducing uncertainties in neutrino detection. In all
cases, the complexity of the strong interaction is a bottleneck in
pursuing these research avenues. The strong-interaction physics is
addressed within SIMDAMA using the ab initio method of lattice
QCD. The method is numerically very demanding and requires massively
parallel computing resources.
As a conclusion of SIMDAMA, the scattering of light by light via
hadrons contribution in the muon g-2 cannot explain the existing
tension between its direct experimental measurement and the
theoretical prediction based on the SM. Neutrinos are more likely to
be scattered by protons at momentum transfers of typical hadronic
scale than previously thought; and the scattering of hypothetical
massive dark matter particles on nuclei via exchange of a Higgs
particle can now better be quantified. And the quark-gluon plasma
emits hard photons at a rate in line with weak-coupling predictions.
In 2021, SIMDAMA provided the world's most precise ab initio
determination of the hadronic light-by-light contribution in the muon
g-2, thereby strengthening the latter quantity as a test of the
Standard Model. The result was included in the 2022 Snowmass White
Paper on the subject (arXiv:2203.15810).
The axial form factor parametrizes the elastic scattering of a
neutrino off a nucleon; a 2022 SIMDAMA calculation of the axial form
factor with controlled errors strengthened a tension with previous
phenomenological determinations of the same form factor.
Finally, the rate at which photons are emitted by the plasma of quarks
and gluons at the typical temperatures reached in collider experiments
has been computed, showing a broad agreement with previous
small-coupling expansions.
determination of the hadronic light-by-light contribution in the muon
g-2, thereby strengthening the latter quantity as a test of the
Standard Model. The result was included in the 2022 Snowmass White
Paper on the subject (arXiv:2203.15810).
The axial form factor parametrizes the elastic scattering of a
neutrino off a nucleon; a 2022 SIMDAMA calculation of the axial form
factor with controlled errors strengthened a tension with previous
phenomenological determinations of the same form factor.
Finally, the rate at which photons are emitted by the plasma of quarks
and gluons at the typical temperatures reached in collider experiments
has been computed, showing a broad agreement with previous
small-coupling expansions.
Under SIMDAMA, major new computational methods were developed. In the
context of the anomalous magnetic moment of the muon, these led in
2021 to the most precise result at the time for the hadronic
light-by-light contribution.
In the finite-temperature context, a new method to compute moments of
the spectrum of emitted photons was developed within SIMDAMA. This is
the first time that such direct information can be obtained on the
photon emissivity without having to solve a numerically ill-posed
inverse problem. First results have been presented at the Lattice 2022
conference and will be published soon.
Nucleon structure calculations with fully quantified uncertainties
have only started to appear in recent years. Within SIMDAMA, two major
such calculations, respectively on the axial form factor and the
pion-nucleon sigma term, have appeared. In particular, the method of
performing a weighted average over different analysis procedures and to use the spread as
a measure of the systematic uncertainty was introduced into this
physics context.
context of the anomalous magnetic moment of the muon, these led in
2021 to the most precise result at the time for the hadronic
light-by-light contribution.
In the finite-temperature context, a new method to compute moments of
the spectrum of emitted photons was developed within SIMDAMA. This is
the first time that such direct information can be obtained on the
photon emissivity without having to solve a numerically ill-posed
inverse problem. First results have been presented at the Lattice 2022
conference and will be published soon.
Nucleon structure calculations with fully quantified uncertainties
have only started to appear in recent years. Within SIMDAMA, two major
such calculations, respectively on the axial form factor and the
pion-nucleon sigma term, have appeared. In particular, the method of
performing a weighted average over different analysis procedures and to use the spread as
a measure of the systematic uncertainty was introduced into this
physics context.