0000000000049800
AUTHOR
Stefan E. Müller
showing 10 related works from this author
Measurement of σ(e+e−→π+π−) from threshold to 0.85 GeV2 using initial state radiation with the KLOE detector
2011
Measurement of σ(e+e−→π+π−) from threshold to 0.85 GeV2 using initial state radiation with the KLOE detector
Measurement of the branching ratio and search for a CP violating asymmetry in the η→π+π−e+e−(γ) decay at KLOE
2009
Abstract We have studied the η → π + π − e + e − ( γ ) decay using about 1.7 fb − 1 collected by the KLOE experiment at the DAΦNE ϕ -factory. This corresponds to about 72 millions η mesons produced in ϕ radiative decays. We have measured the branching ratio, inclusive of radiative effects, with 4% accuracy: BR ( η → π + π − e + e − ( γ ) ) = ( 26.8 ± 0.9 Stat . ± 0.7 Syst . ) × 10 − 5 . We have obtained the first measurement of the CP-odd ππ – ee decay planes angular asymmetry, A ϕ = ( − 0.6 ± 2.5 Stat . ± 1.8 Syst . ) × 10 − 2 .
Observation of the rare η→e+e−e+e− decay with the KLOE experiment
2011
Abstract We report the first observation of the rare η → e + e − e + e − ( γ ) decay based on 1.7 fb − 1 collected by the KLOE experiment at the DAΦNE ϕ-factory. The selection of the e + e − e + e − final state is fully inclusive of radiation. We have identified 362 ± 29 events resulting in a branching ratio of ( 2.4 ± 0.2 stat + bckg ± 0.1 syst ) × 10 − 5 .
Physics with the KLOE-2 experiment at the upgraded DAFNE
2010
Investigation at a $\phi$--factory can shed light on several debated issues in particle physics. We discuss: i) recent theoretical development and experimental progress in kaon physics relevant for the Standard Model tests in the flavor sector, ii) the sensitivity we can reach in probing CPT and Quantum Mechanics from time evolution of entangled kaon states, iii) the interest for improving on the present measurements of non-leptonic and radiative decays of kaons and eta/eta$^\prime$ mesons, iv) the contribution to understand the nature of light scalar mesons, and v) the opportunity to search for narrow di-lepton resonances suggested by recent models proposing a hidden dark-matter sector. We…
Search for the decay ϕ→K0K¯0γ with the KLOE experiment
2009
Abstract We have searched for the decay ϕ → K 0 K ¯ 0 γ , by detecting K S pairs plus a photon and with the K S -mesons decaying to π + π − , in a sample of about 1.5 × 10 9 ϕ-decays collected by the KLOE experiment at DAΦNE. The reaction proceeds through the intermediate states f 0 ( 980 ) γ , a 0 ( 980 ) γ . We find five events with 3.2 events expected from background processes. We obtain the upper limit: BR ( ϕ → K 0 K ¯ 0 γ ) 1.9 × 10 − 8 at 90% CL.
Searches for anisotropies in the arrival directions of the highest energy cosmic rays detected by the Pierre Auger Observatory
2015
We analyze the distribution of arrival directions of ultra-high energy cosmic rays recorded at the Pierre Auger Observatory in 10 years of operation. The data set, about three times larger than that used in earlier studies, includes arrival directions with zenith angles up to $80^\circ$, thus covering from $-90^\circ$ to $+45^\circ$ in declination. After updating the fraction of events correlating with the active galactic nuclei (AGNs) in the V��ron-Cetty and V��ron catalog, we subject the arrival directions of the data with energies in excess of 40 EeV to different tests for anisotropy. We search for localized excess fluxes and for self-clustering of event directions at angular scales up t…
Quest for precision in hadronic cross sections at low energy: Monte Carlo tools vs. experimental data
2010
We present the achievements of the last years of the experimental and theoretical groups working on hadronic cross section measurements at the low-energy e (+) e (-) colliders in Beijing, Frascati, Ithaca, Novosibirsk, Stanford and Tsukuba and on tau decays. We sketch the prospects in these fields for the years to come. We emphasise the status and the precision of the Monte Carlo generators used to analyse the hadronic cross section measurements obtained as well with energy scans as with radiative return, to determine luminosities and tau decays. The radiative corrections fully or approximately implemented in the various codes and the contribution of the vacuum polarisation are discussed.
The anomalous magnetic moment of the muon in the Standard Model
2020
We are very grateful to the Fermilab Directorate and the Fermilab Theoretical Physics Department for their financial and logistical support of the first workshop of the Muon g -2 Theory Initiative (held near Fermilab in June 2017) [123], which was crucial for its success, and indeed for the successful start of the Initiative. Financial support for this workshop was also provided by the Fermilab Distinguished Scholars program, the Universities Research Association through a URA Visiting Scholar award, the Riken Brookhaven Research Center, and the Japan Society for the Promotion of Science under Grant No. KAKEHNHI-17H02906. We thank Shoji Hashimoto, Toru Iijima, Takashi Kaneko, and Shohei Nis…
Fast-neutron-induced fission cross section of Pu242 measured at the neutron time-of-flight facility nELBE
2019
The fast-neutron-induced fission cross section of $^{242}\mathrm{Pu}$ was measured at the neutron time-of-flight facility $n$ELBE. A parallel-plate fission ionization chamber with novel, homogeneous, large-area $^{242}\mathrm{Pu}$ deposits on Si-wafer backings was used to determine this quantity relative to the IAEA neutron cross-section standard $^{235}\mathrm{U}(n,f)$ in the energy range of 0.5 to 10 MeV. The number of target nuclei was determined from the measured spontaneous fission rate of $^{242}\mathrm{Pu}$. This helps to reduce the influence of the fission fragment detection efficiency on the cross section. Neutron transport simulations performed with geant4, mcnp6, and fluka2011 ar…
Measurement of the η→3π0 slope parameter α with the KLOE detector
2010
Abstract We present a measurement of the slope parameter α for the η → 3 π 0 decay, with the KLOE experiment at the DAΦNE ϕ -factory, based on a background free sample of ∼17 million η mesons produced in ϕ radiative decays. By fitting the event density in the Dalitz plot we determine α = − 0.0301 ± 0.0035 stat − 0.0035 + 0.0022 syst . The result is in agreement with recent measurements from hadro- and photo-production experiments.