95 research outputs found
Proposal to search for a dark photon in on target collisions at DANE linac
Photon-like particles are predicted in many extensions of the Standard Model.
They have interactions similar to the photon, are vector bosons, and can be
produced together with photons. The present paper proposes a search for such
particles in the process in a positron-on-target
experiment, exploiting the positron beam of the DANE linac at the
Laboratori Nazionali di Frascati, INFN. In one year of running a sensitivity in
the relative interaction strength down to is achievable, in the
mass region from 2.5 MeV 20 MeV. The proposed experimental setup and the
analysis technique is discussed.Comment: 19 pages, 21 figures, version accepted for publication in Adv. in HE
The PADME experiment at LNF
Massive photon-like particles are predicted in many extensions of the
Standard Model. They have interactions similar to the photon, are vector
bosons, and can be produced together with photons. The PADME experiment
proposes a search for the dark photon () in the
process in a positron-on-target experiment, exploiting the positron beam of the
DANE linac at the Laboratori Nazionali di Frascati, INFN. In one year of
running a sensitivity in the relative interaction strength down to is
achievable, in the mass region from 2.5 MeV 22.5 MeV. The proposed
experimental setup and the analysis technique is discussed.Comment: to be published in the DHF2014 proceedings EPJ Web of Conference
Search for Dark Photon at NA48/2, and measurement of π0 form factor
The NA48/2 experiment at CERN performed a search for the dark photon (A') via the decay chain pi(0) -> gamma A', A' -> e(+)e(-) . Using a sample of similar to 1.7.10(7) neutral pions tagged from K-+/- -> pi(+/-)pi x(D)(0) and K +/- -> mu(+/-) pi(0)(D)nu decays collected in 2003-04 no signal is observed. The limits in the plane dark photon mixing parameter epsilon(2) versus its mass m(A') are reported. The NA62-RK experiment collected, during the 2007 data taking, a large sample of neutral pion Dalitz decays with a trigger optimised for electrons final states with respect to NA48/2 one. We report the measurement of the pi(0) electromagnetic transition form factor (TFF) slope parameter (a) based on a sample of similar to 1.10(6) pi(0)(D) decays. The preliminary measured value a = (3.70 +/- 0:53(stat) +/- 0.36(syst)).10(2) is compatible with theoretical expectations and previous measurements
Resonant search for the X17 boson at PADME
We discuss the experimental reach of the Frascati PADME experiment in
searching for new light bosons via their resonant production in positron
annihilation on fixed target atomic electrons. A scan in the mass range around
17 MeV will thoroughly probe the particle physics interpretation of the anomaly
observed by the ATOMKI nuclear physics experiment. In particular, for the case
of a spin-1 boson, the viable parameter space can be fully covered in a few
months of data taking.Comment: 8 pages, 5 figures and 1 tabl
Resonant production of dark photons in positron beam dump experiments
Positrons beam dump experiments have unique features to search for very
narrow resonances coupled superweakly to pairs. Due to the continue
loss of energy from soft photon bremsstrahlung, in the first few radiation
lengths of the dump a positron beam can continuously scan for resonant
production of new resonances via annihilation off an atomic in the
target. In the case of a dark photon kinetically mixed with the photon,
this production mode is of first order in the electromagnetic coupling
, and thus parametrically enhanced with respect to the
production mode and to the
bremsstrahlung in nucleon scattering so far considered. If the lifetime
is sufficiently long to allow the to exit the dump, decays
could be easily detected and distinguished from backgrounds. We explore the
foreseeable sensitivity of the Frascati PADME experiment in searching with this
technique for the MeV dark photon invoked to explain the Be anomaly
in nuclear transitions.Comment: 11 pages, 4 figures, added 3 references and some clarifications.
Version accepted for publication in Phys. Rev.
Electrophysiological and Neuropsychological Indices of Cognitive Dysfunction in Patients with Chronic Insomnia and Severe Benzodiazepine Use Disorder.
Benzodiazepine (BDZ) misuse is a growing health problem, with 1-2% of patients under BDZ treatment meeting the criteria for use disorder or dependence. Although BDZ addiction potential has been known for decades, much remains unknown its effects on brain functions. The aim of this study was to assess the neuropsychological and neurophysiological profile of a group of chronic insomniacs taking long-term high doses of benzodiazepine. We recruited 17 consecutive patients admitted to our third-level Sleep Medicine Unit for drug discontinuation (7 males, mean age 49.2 ± 11.2 years, mean education 13.7 ± 3.9 years, mean daily diazepam-equivalent BDZ: 238.1 ± 84.5 mg) and 17 gender/age-matched healthy controls (7 males, mean age 46.8 ± 14.1 years, mean education 13.5 ± 4.5 years). We performed a full neuropsychological evaluation of all subjects and recorded their scalp event-related potentials (Mismatch-Passive Oddball-Paradigm and Active Oddball P300 Paradigm). Patients with chronic insomnia and BDZ use disorder showed a profound frontal lobe executive dysfunction with significant impairment in the cognitive flexibility domain, in face of a preserved working, short and long-term memory. In patients, P300 amplitude tended to be smaller, mainly over the frontal regions, compared to controls. BDZ use disorder has a severe cognitive impact on chronic insomnia patients. Long-term high-dose BDZ intake should be carefully evaluated and managed by clinicians in this specific patient population, especially in relation to risky activities
Dark sectors 2016 Workshop: community report
This report, based on the Dark Sectors workshop at SLAC in April 2016,
summarizes the scientific importance of searches for dark sector dark matter
and forces at masses beneath the weak-scale, the status of this broad
international field, the important milestones motivating future exploration,
and promising experimental opportunities to reach these milestones over the
next 5-10 years
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