Abstract
The great success of the Standard Model has reached its maximum with the Higgs boson discovery. However, several anomalies observed in the universe when applying the gravitational theory, ...lead to believe that the visible matter is not the only constituent of the universe. A new matter component, called dark matter, must be introduced through an extension of the Standard Model. A simple scenario consisting in adding a new gauge symmetry
U
D
(1) and, as a consequence, a new (massive) gauge boson, the dark photon A′. PADME is a new experiment of the Laboratori Nazionali di Frascati searching for the A′, decaying invisibly, produced in the fixed target annihilation
e+e
−
→ γA′. The technique used by the experiment to probe the dark photon hypothesis is the missing mass method. The PADME experiment took data in two runs. Some preliminary highlights from the ongoing data analysis effort are presented.
We have measured the ratio Rϕ=BR(ϕ→η′γ)/BR(ϕ→ηγ) by looking for the radiative decays ϕ→η′γ and ϕ→ηγ into the final states π+π−7γ and 7γ, respectively, in a sample of ∼1.4×109ϕ mesons produced at the ...Frascati ϕ factory. We obtain Rϕ=(4.77±0.09stat±0.19syst)×10−3, from which we derive BR(ϕ→η′γ)=(6.20±0.11stat±0.25syst)×10−5. Assuming the η′ has zero gluonium content, we extract the pseudoscalar mixing angle in the quark-flavor basis, φP=(41.4±0.3stat±0.7syst±0.6th)°. Combining the value of Rϕ with other constraints, we estimate the fractional gluonium content of the η′ to be Z2=0.14±0.04 and the mixing angle to be φP=(39.7±0.7)°.
Recent KLOE measurements allowing precision tests of lepton flavor universality are here briefly described, with particular emphasis on the analysis for the ratio of branching fractions for the K ± → ...e± e and K± → μ± μ decays. The sensitivity of these tests, all obtained from the study of kaon decays, is compared to that from other sources.
Status of the PADME experiment Spagnolo, Stefania
Journal of physics. Conference series,
12/2018, Letnik:
1137, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Among the theoretical models addressing the dark matter problem, the category based on a secluded sector is attracting increasing interest. The PADME experiment, at the Laboratori Nazionali di ...Frascati of INFN, is designed to be sensitive to the production of a low mass gauge boson A′ of a new U(1) symmetry holding for dark sector particles and weakly coupled to the Standard Model photon. The DAΦNE Beam-Test Facility at LNF will provide a high intensity, mono-energetic positron beam impinging on a low Z target. The PADME detector will measure with high precision the momentum of the photon, produced along with the A′ boson in e+e− → A′+γ annihilation in the target, thus allowing to measure the A′ mass as the missing mass in the final state. This technique, particularly useful in case of invisible decays of the A′ boson, will be exploited for the first time in a fixed target experiment. Simulation studies predict a sensitivity on the interaction strength (ϵ2 parameter) down to 10−6, in the mass region 1 MeV < MA′ < 23.7 MeV. In this work the physics potential, the experimental strategy and the status of readiness of the experiment will be reviewed.
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