5,998 research outputs found
A Fresh Approach to Forecasting in Astroparticle Physics and Dark Matter Searches
We present a toolbox of new techniques and concepts for the efficient
forecasting of experimental sensitivities. These are applicable to a large
range of scenarios in (astro-)particle physics, and based on the Fisher
information formalism. Fisher information provides an answer to the question
what is the maximum extractable information from a given observation?. It is a
common tool for the forecasting of experimental sensitivities in many branches
of science, but rarely used in astroparticle physics or searches for particle
dark matter. After briefly reviewing the Fisher information matrix of general
Poisson likelihoods, we propose very compact expressions for estimating
expected exclusion and discovery limits (equivalent counts method). We
demonstrate by comparison with Monte Carlo results that they remain
surprisingly accurate even deep in the Poisson regime. We show how correlated
background systematics can be efficiently accounted for by a treatment based on
Gaussian random fields. Finally, we introduce the novel concept of Fisher
information flux. It can be thought of as a generalization of the commonly used
signal-to-noise ratio, while accounting for the non-local properties and
saturation effects of background and instrumental uncertainties. It is a
powerful and flexible tool ready to be used as core concept for informed
strategy development in astroparticle physics and searches for particle dark
matter.Comment: 33 pages, 12 figure
Representing Structural Information of Helical Charge Distributions in Cylindrical Coordinates
Structural information in the local electric field produced by helical charge
distributions, such as dissolved DNA, is revealed in a straightforward manner
employing cylindrical coordinates. Comparison of structure factors derived in
terms of cylindrical and helical coordinates is made. A simple coordinate
transformation serves to relate the Green function in cylindrical and helical
coordinates. We also compare the electric field on the central axis of a single
helix as calculated in both systems.Comment: 11 pages in plain LaTex, no figures. Accepted for publication in PRE
March, 199
A Unique Multi-Messenger Signal of QCD Axion Dark Matter
We propose a multi-messenger probe of QCD axion Dark Matter based on
observations of black hole-neutron star binary inspirals. It is suggested that
a dense Dark Matter spike may grow around intermediate mass black holes
(). The presence of such a spike produces
two unique effects: a distinct phase shift in the gravitational wave strain
during the inspiral and an enhancement of the radio emission due to the
resonant axion-photon conversion occurring in the neutron star magnetosphere
throughout the inspiral and merger. Remarkably, the observation of the
gravitational wave signal can be used to infer the Dark Matter density and,
consequently, to predict the radio emission. We study the projected reach of
the LISA interferometer and next-generation radio telescopes such as the Square
Kilometre Array. Given a sufficiently nearby system, such observations will
potentially allow for the detection of QCD axion Dark Matter in the mass range
to .Comment: 5 pages, 3 figures. Appendix added with additional figures. Updated
to published versio
Optimal simulation-based Bayesian decisions
We present a framework for the efficient computation of optimal Bayesian
decisions under intractable likelihoods, by learning a surrogate model for the
expected utility (or its distribution) as a function of the action and data
spaces. We leverage recent advances in simulation-based inference and Bayesian
optimization to develop active learning schemes to choose where in parameter
and action spaces to simulate. This allows us to learn the optimal action in as
few simulations as possible. The resulting framework is extremely simulation
efficient, typically requiring fewer model calls than the associated posterior
inference task alone, and a factor of more efficient than
Monte-Carlo based methods. Our framework opens up new capabilities for
performing Bayesian decision making, particularly in the previously challenging
regime where likelihoods are intractable, and simulations expensive.Comment: 12 pages, 4 figure
Dark Matter Model or Mass, but Not Both: Assessing Near-Future Direct Searches with Benchmark-free Forecasting
Forecasting the signal discrimination power of dark matter (DM) searches is
commonly limited to a set of arbitrary benchmark points. We introduce new
methods for benchmark-free forecasting that instead allow an exhaustive
exploration and visualization of the phenomenological distinctiveness of DM
models, based on standard hypothesis testing. Using this method, we reassess
the signal discrimination power of future liquid Xenon and Argon direct DM
searches. We quantify the parameter regions where various non-relativistic
effective operators, millicharged DM, and magnetic dipole DM can be
discriminated, and where upper limits on the DM mass can be found. We find that
including an Argon target substantially improves the prospects for
reconstructing the DM properties. We also show that only in a small region with
DM masses in the range 20-100 GeV and DM-nucleon cross sections a factor of a
few below current bounds can near-future Xenon and Argon detectors discriminate
both the DM-nucleon interaction and the DM mass simultaneously. In all other
regions only one or the other can be obtained.Comment: 5 pages, 4 figures + appendices. Code for the calculations throughout
the paper can be found at
https://github.com/tedwards2412/benchmark_free_forecasting/ . v2: Minor
corrections, matches version published in PRL as "Assessing Near-Future
Direct Dark Matter Searches with Benchmark-Free Forecasting
New Projections for Dark Matter Searches with Paleo-Detectors
Paleo-detectors are a proposed experimental technique to search for dark
matter (DM). In lieu of the conventional approach of operating a tonne-scale
real-time detector to search for DM-induced nuclear recoils, paleo-detectors
take advantage of small samples of naturally occurring rocks on Earth that have
been deep underground ( km), accumulating nuclear damage tracks from
recoiling nuclei for Gyr. Modern microscopy techniques promise
the capability to read out nuclear damage tracks with nanometer resolution in
macroscopic samples. Thanks to their Gyr integration times,
paleo-detectors could constitute nuclear recoil detectors with keV recoil
energy thresholds and 100 kilotonne-yr exposures. This combination would allow
paleo-detectors to probe DM-nucleon cross sections orders of magnitude below
existing upper limits from conventional direct detection experiments. In this
article, we use improved background modeling and a new spectral analysis
technique to update the sensitivity forecast for paleo-detectors. We
demonstrate the robustness of the sensitivity forecast to the (lack of)
ancillary measurements of the age of the samples and the parameters controlling
the backgrounds, systematic mismodeling of the spectral shape of the
backgrounds, and the radiopurity of the mineral samples. Specifically, we
demonstrate that even if the uranium concentration in paleo-detector samples is
(per weight), many orders of magnitude larger than what we expect in
the most radiopure samples obtained from ultra basic rock or marine evaporite
deposits, paleo-detectors could still probe DM-nucleon cross sections below
current limits. For DM masses GeV/, the sensitivity of
paleo-detectors could still reach down all the way to the conventional neutrino
floor in a Xe-based direct detection experiment.Comment: Invited contribution to Instruments "Special Issue Innovative
Experimental Techniques for Direct Dark Matter Detection)". 30 pages, 5
figures, 1 table. Code available at https://github.com/sbaum90/paleoSpec and
https://github.com/sbaum90/paleoSen
Digging for Dark Matter: Spectral Analysis and Discovery Potential of Paleo-Detectors
Paleo-detectors are a recently proposed method for the direct detection of
Dark Matter (DM). In such detectors, one would search for the persistent damage
features left by DM--nucleus interactions in ancient minerals. Initial
sensitivity projections have shown that paleo-detectors could probe much of the
remaining Weakly Interacting Massive Particle (WIMP) parameter space. In this
paper, we improve upon the cut-and-count approach previously used to estimate
the sensitivity by performing a full spectral analysis of the background- and
DM-induced signal spectra. We consider two scenarios for the systematic errors
on the background spectra: i) systematic errors on the normalization only, and
ii) systematic errors on the shape of the backgrounds. We find that the
projected sensitivity is rather robust to imperfect knowledge of the
backgrounds. Finally, we study how well the parameters of the true WIMP model
could be reconstructed in the hypothetical case of a WIMP discovery.Comment: 14 pages, 5 figures, code available at
https://github.com/tedwards2412/paleo_detectors/ . v2: Added additional
analysis theory details, matches version published in PR
Transient Radio Signatures from Neutron Star Encounters with QCD Axion Miniclusters
The QCD axion is expected to form dense structures known as axion
miniclusters if the Peccei-Quinn symmetry is broken after inflation.
Miniclusters that have survived until today will interact with neutron stars
(NSs) in the Milky Way to produce transient radio signals from axion-photon
conversion in the NS magnetosphere. We quantify the properties of these
encounters and find that they occur frequently
(); last between a day and a few months;
are spatially clustered towards the Galactic center; and can reach observable
fluxes. These radio transients are within reach of current generation
telescopes and therefore offer a promising pathway to discovering QCD axion
dark matter.Comment: 11 pages, 5 figures. Code is available online at
https://github.com/bradkav/axion-miniclusters/ (archived at
https://doi.org/10.5281/zenodo.4006128 ). Joint submission with "Stellar
Disruption of Axion Miniclusters in the Milky Way" in astro-ph
(arXiv:2011.05377). Updated to match published versio
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