Search arXiv⌕ Search
Home/Archive/arXiv

arXiv · hep-ex/0609059

An Improved Limit on Invisible Decays of Positronium

A. Badertscher·P. Crivelli·W. Fetscher·U. Gendotti·S. Gninenko·V. Postoev·A. Rubbia·V. Samoylenko·D. Sillou
View original source ↗Read source document ↗Export metadata ↓

Abstract

The results of a new search for positronium decays into invisible final states are reported. Convincing detection of this decay mode would be a strong evid ence for new physics beyond the Standard Model (SM): for example the existence of extra--dimensions, of milli-charged particles, of new light gauge bosons or of mirror particles. Mirror matter could be a relevant dark matter candidate. In this paper the setup and the results of a new experiment are presented. In a collected sample of about $(6.31\pm0.28) \times 10^6$ orthopositronium decay s, no evidence for invisible decays in an energy window [0,80] keV was found and an upper limit on the branching ratio of orthopositronium \invdecay could be set: $\binvdecay<4.2\times 10^{-7}$ (90% C.L.) Our results provide a limit on the photon mirror-photon mixing strength $ε\leq 1.55\times 10^{-7}$ (90% C.L.) and rule out particles lighter than the electron mass with a fraction $Q_x \leq 3.4 \times 10^{-5}$ of the electron charge. Furthermore, upper limits on the branching ratios for the decay of parapositronium $Br(p-Ps\to invisible)\leq 4.3 \times 10^{-7}$ (90% C.L.) and the direct annihilation $Br(e^+e^-\to invisible)\leq 2.1 \times 10^{-8}$ (90% C.L.) could be set.

Explore related subjects

hep-ex

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

A. Badertscher, P. Crivelli, W. Fetscher, U. Gendotti, S. Gninenko, V. Postoev, A. Rubbia, V. Samoylenko, D. Sillou. 2006-10-05. An Improved Limit on Invisible Decays of Positronium. https://doi.org/10.1103/physrevd.75.032004

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related papers

arXiv2026

First broadband search for fixed-polarization dark photon dark matter with GigaBREAD

We present the first search for fixed-polarization dark photon (DP) dark matter in the 44-52$μ\mathrm{eV}$ mass range, corresponding to 10.7-12.5GHz. GigaBREAD is a room-temperature broadband dish antenna experiment in which DP convert to ordinary photons on a cylindrical metallic emission surface and are focused onto a radio-frequency receiver. Previous searches, including GigaBREAD and several other dish antenna searches, have assumed randomly polarized DP dark matter. However, vector dark matter produced by a misalignment-like mechanism may retain an approximately fixed polarization, leading to sidereal modulation of the detector response as the Earth rotates. We reanalyze the GigaBREAD data using a polarization-matched likelihood that accounts for the time-dependent projection of a fixed DP polarization onto the detector axis. We find no evidence for a fixed-polarization DP signal and set upper limits on the kinetic mixing parameter at the level of $χ\sim10^{-12}$. These limits are about $20\%$ better than a naive limit obtained by rescaling the previous GigaBREAD limit under the fixed-polarization assumption.

hep-ex↗
arXiv2026

Search for dark matter axions at 1-2 micro-eV with a RADES-DarkQuantum haloscope at CERN

The QCD axion remains one of the most compelling candidates for the dark matter of the Universe, yet the mass range around $1$\text{--}\SI{2}{\micro\electronvolt} remains essentially unexplored. In this paper, we describe a proposal to employ CERN's M1 superconducting magnet to deploy a haloscope to perform a search for galactic axion and axion-like particle dark matter providing continuous coverage from approximately 1.2 to 1.8 \SI{}{\micro\electronvolt}. Under conservative assumptions, the experiment can reach the QCD axion band over a significant fraction of the scanned range, while optimistic detector performance would allow sensitivity to benchmark models such as KSVZ and DFSZ over a large part of the explored mass interval. With the current long shut-down of CERN's accelerators providing a unique and timely window, such an experiment will deliver high-impact results even in conservative scenarios and potentially delivering a definitive test of the axion dark matter paradigm in the unexplored $1$\text{--}\SI{2}{\micro\electronvolt} mass range.

hep-ex↗
arXiv2026

Data-quality monitoring of luminosity blocks with ATLAS Open Data: an open benchmark and a learned within-run detector

Data-quality monitoring at the LHC decides, luminosity block by luminosity block, which collision data enter physics analyses, yet its methods cannot be compared openly because the experiments' monitoring data are not public. We construct a public benchmark from the ATLAS Open Data release of the 2015--2016 proton--proton collisions at $\sqrt{s}=13$~TeV: 1289-bin histograms of reconstructed jets, electrons, photons, muons and the missing transverse momentum computed from them, for 39\,828 luminosity blocks of all 217 runs in the Good Run Lists; eight types of detector defects injected at event level at three strengths; real-data labels from the Good Run Lists and the liquid-argon calorimeter error flag; and a time-ordered protocol in which every detector is trained and calibrated on earlier runs only. Histogram shapes differ far more between runs than within a run (median $χ^2/n_\mathrm{dof}$ of 5.9 against 1.1), so references and autoencoders built across runs fail, and all competitive detectors use residuals with respect to a robust reference of each run. A gradient-boosted classifier on position-invariant features of these residuals, trained on synthetic defects and calibrated by split-conformal prediction, detects 43\% of the luminosity blocks with injected defects at a false-positive rate of 1.0\%, against 25\% for a matched-filter scan and 63\% for a single-histogram test that knows the defect pattern. For defect types excluded from its training, its efficiency falls to 18\%; adding pattern-agnostic synthetic detector failures to the training raises it to 34\%, above the scan, at a cost of three percentage points on the known types.

hep-ex↗