35 research outputs found
From Hadronic Cross Section to the measurement of the Vacuum Polarization at KLOE: a fascinating endeavour
The KLOE experiment at the DANE in Frascati is the first
to have employed Initial State Radiation (ISR) to precisely determine the
cross section below 1 GeV. Such a measurement is
particularly important to test the Standard Model (SM) calculation for the
of the muon, where a long standing 3 discrepancy is observed. I
will review the ISR activity in KLOE in the last 18 years from the measurement
of the hadronic cross section to the first direct determination of the
time-like complex running in the region below 1 GeV.Comment: 13 pages, 8 figures. Contribution to the proceedings of the KLOE-2
Workshop on e+e- collision physics at 1 GeV, 26-28 October 2016 INFN -
Laboratori Nazionali di Frascati, Ital
Towards a full NNLO Monte Carlo generator for low energy data into leptons and hadrons
During the last 15 years the Radio MonteCarLow Working Group has been
providing valuable support to the development of radiative corrections and
Monte Carlo event generators for low energy data and -lepton
decays. While the working group has been operating for more than 15 years
without a formal basis for funding, parts of our program have recently been
included as a Joint Research Initiative in the group application of the
European hadron physics community, STRONG2020, to the European Union, with a
more specific goal of creating an annotated database for low-energy hadronic
cross sections in collisions. In parallel the theory community is
continuing its effort towards the realization of improved Monte Carlo
generators with for low energy data into hadrons. Full NNLO
corrections in the leptonic sector are to be combined with an improved
treatment of radiative corrections involving pions. This is of relevance for
the precise determination of the leading hadronic contribution to the muon g-2.
We will report on these initiatives.Comment: 6 pages, Contribution to the proceedings of the European Physical
Society Conference on High Energy Physics (EPS-HEP2023), 21-25 August 2023,
Hamburg, German
New results from the Muon g-2 Experiment
The Muon g-2 experiment at Fermilab has published the first result on Run-1
dataset in 2021 showing a good agreement with the previous experimental result
at Brookhaven National Laboratory at comparable precision (0.46 ppm). In August
2023 we released our new result from Run-2 and Run-3 datasets which allowed to
measure to 0.21 ppm, a more than two-fold improved precision respect to
Run-1, and which allowed to reach a precision of 0.20 ppm when combined with
the Run-1 result. We will discuss the improvements of the Run-2/3 analysis
respect to Run-1, the current status of the theory prediction, and the future
prospects.Comment: 10 pages, 9 figures, Contribution to the proceedings of the European
Physical Society Conference on High Energy Physics (EPS-HEP2023), 21-25
August 2023, Hamburg, German
The New Muon g−2 experiment at Fermilab
AbstractThere is a long standing discrepancy between the Standard Model prediction for the muon g−2 and the value measured by the Brookhaven E821 Experiment. At present the discrepancy stands at about three standard deviations, with a comparable accuracy between experiment and theory. Two new proposals – at Fermilab and J-PARC – plan to improve the experimental uncertainty by a factor of 4, and it is expected that there will be a significant reduction in the uncertainty of the Standard Model prediction. I will review the status of the planned experiment at Fermilab, E989, which will analyse 21 times more muons than the BNL experiment and discuss how the systematic uncertainty will be reduced by a factor of 3 such that a precision of 0.14 ppm can be achieved
An alternative evaluation of the leading-order hadronic contribution to the muon g-2 with MUonE
We propose an alternative method to extract the leading-order hadronic
contribution to the muon g-2, , with the MUonE experiment.
In contrast to the traditional method based on the integral of the hadronic
contribution to the running of the effective fine-structure constant
in the space-like region, our approach relies on the
computation of the derivatives of at zero squared
momentum transfer . We show that this approach allows to extract
of the total value of from the MUonE data, while the
remaining can be computed combining perturbative QCD and data on
annihilation to hadrons. This leads to a competitive evaluation of
which is robust against the parameterization used to model
in the MUonE kinematic region, thanks to the
analyticity properties of , which can be expanded as a
polynomial at .Comment: 13 pages, 10 figure