| 1. |
- Allanach, Benjamin C., et al.
(författare)
-
Simple and statistically sound strategies for analysing physical theories
- 2022
-
Ingår i: Reports on progress in physics (Print). - : Institute of Physics Publishing (IOPP). - 0034-4885 .- 1361-6633. ; 85:5
-
Forskningsöversikt (refereegranskat)abstract
- Physical theories that depend on many parameters or are tested against data from many different experiments pose unique challenges to statistical inference. Many models in particle physics, astrophysics and cosmology fall into one or both of these categories. These issues are often sidestepped with statistically unsound ad hoc methods, involving intersection of parameter intervals estimated by multiple experiments, and random or grid sampling of model parameters. Whilst these methods are easy to apply, they exhibit pathologies even in low-dimensional parameter spaces, and quickly become problematic to use and interpret in higher dimensions. In this article we give clear guidance for going beyond these procedures, suggesting where possible simple methods for performing statistically sound inference, and recommendations of readily-available software tools and standards that can assist in doing so. Our aim is to provide any physicists lacking comprehensive statistical training with recommendations for reaching correct scientific conclusions, with only a modest increase in analysis burden. Our examples can be reproduced with the code publicly available at Zenodo.
|
|
| 2. |
- Balázs, Csaba, et al.
(författare)
-
Cosmological constraints on decaying axion-like particles : a global analysis
- 2022
-
Ingår i: Journal of Cosmology and Astroparticle Physics. - : IOP Publishing. - 1475-7516. ; :12
-
Tidskriftsartikel (refereegranskat)abstract
- Axion-like particles (ALPs) decaying into photons are known to affect a wide range of astrophysical and cosmological observables. In this study we focus on ALPs with masses in the keV–MeV range and lifetimes between 104 and 1013 seconds, corresponding to decays between the end of Big Bang Nucleosynthesis and the formation of the Cosmic Microwave Background (CMB). Using the CosmoBit module of the global fitting framework GAMBIT, we combine state-of-the-art calculations of the irreducible ALP freeze-in abundance, primordial element abundances (including photodisintegration through ALP decays), CMB spectral distortions and anisotropies, and constraints from supernovae and stellar cooling. This approach makes it possible for the first time to perform a global analysis of the ALP parameter space while varying the parameters of ΛCDM as well as several nuisance parameters. We find a lower bound on the ALP mass of around ma > 300 keV, which can only be evaded if ALPs are stable on cosmological timescales. Future observations of CMB spectral distortions with a PIXIE-like mission are expected to improve this bound by two orders of magnitude.
|
|
| 3. |
- Emken, Timon, et al.
(författare)
-
Electron recoils from terrestrial upscattering of inelastic dark matter
- 2022
-
Ingår i: Physical Review D. - 2470-0010 .- 2470-0029. ; 105:5
-
Tidskriftsartikel (refereegranskat)abstract
- The growing interest in the interactions between dark matter particles and electrons has received a further boost by the observation of an excess in electron recoil events in the XENON1T experiment. Of particular interest are dark matter models in which the scattering process is inelastic, such that the ground state can upscatter into an excited state. The subsequent exothermic downscattering of such excited states on electrons can lead to observable signals in direct detection experiments and gives a good fit to the XENON1T excess. In this work, we study terrestrial upscattering, i.e., inelastic scattering of dark matter particles on nuclei in the Earth, as a plausible origin of such excited states. Using both analytical and Monte Carlo methods, we obtain detailed predictions of their density and velocity distribution. These results enable us to explore the time dependence of the flux of excited states resulting from the rotation of the Earth. For the case of XENON1T, we find the resulting daily modulation of the electron recoil signal to be at the level of 10% with a strong dependence on the dark matter mass.
|
|
| 4. |
- Nippel, Kathrin, et al.
(författare)
-
Constraining Dark Matter Annihilation with Cosmic Ray Antiprotons using Neural Networks
- 2022
-
Ingår i: 17th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2021), 26 August-3 September 2021, Valencia. - : Institute of Physics Publishing (IOPP).
-
Konferensbidrag (refereegranskat)abstract
- The interpretation of indirect detection experiments searching for dark matter annihilations requires computationally expensive simulations of cosmic-ray propagation. We present a new method based on Recurrent Neural Networks that significantly accelerates simulations of secondary and dark matter cosmic ray antiprotons. This approach allows for an efficient marginalization over the nuisance parameters of a cosmic ray propagation model in order to perform parameter scans for a wide range of dark matter models. We present resulting constraints using the most recent AMS-02 antiproton data on dark matter WIMP models. The speed-up achieved with our method results in a runtime two orders of magnitude below a conventional Monte Carlo approach, once the neural network has been trained.
|
|
