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Title: Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor

Abstract

Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments are said to run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable through a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that, using only spectral information, the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions it can still be surpassed using timing information, and so the neutrino floor is not an absolute limit on the sensitivitymore » of Direct Detection experiments.« less

Authors:
 [1]
  1. Institut d’Astrophysique de Paris, 98 bis boulevard Arago, 75014 Paris (France)
Publication Date:
Sponsoring Org.:
SCOAP3, CERN, Geneva (Switzerland)
OSTI Identifier:
22454517
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 03; Other Information: PUBLISHER-ID: JCAP03(2015)012; OAI: oai:repo.scoap3.org:9482; Article funded by SCOAP3. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 License. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTROPHYSICS; CROSS SECTIONS; DETECTION; GEV RANGE; MODULATION; NONLUMINOUS MATTER; PHASE SHIFT; RECOILS; SIGNALS; SOLAR NEUTRINOS; SPECTRA; TIME DEPENDENCE; VELOCITY

Citation Formats

Davis, Jonathan H. Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor. United States: N. p., 2015. Web. doi:10.1088/1475-7516/2015/03/012.
Davis, Jonathan H. Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor. United States. doi:10.1088/1475-7516/2015/03/012.
Davis, Jonathan H. 2015. "Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor". United States. doi:10.1088/1475-7516/2015/03/012.
@article{osti_22454517,
title = {Dark matter vs. neutrinos: the effect of astrophysical uncertainties and timing information on the neutrino floor},
author = {Davis, Jonathan H.},
abstractNote = {Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments are said to run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable through a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that, using only spectral information, the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions it can still be surpassed using timing information, and so the neutrino floor is not an absolute limit on the sensitivity of Direct Detection experiments.},
doi = {10.1088/1475-7516/2015/03/012},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 03,
volume = 2015,
place = {United States},
year = 2015,
month = 3
}
  • Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments are said to run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable throughmore » a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that, using only spectral information, the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions it can still be surpassed using timing information, and so the neutrino floor is not an absolute limit on the sensitivity of Direct Detection experiments.« less
  • The effects of astrophysical uncertainties on the exclusion limits at dark matter direct detection experiments are investigated for three scenarios: elastic, momentum dependent, and inelastically scattering dark matter. We find that varying the dark matter galactic escape velocity and the Sun's circular velocity can lead to significant variations in the exclusion limits for light (< or approx. 10 GeV) elastic and inelastic scattering dark matter. We also calculate the limits using 100 velocity distributions extracted from the Via Lactea II and GHALO N-body simulations and find that a Maxwell-Boltzmann distribution with the same astrophysical parameters generally sets less constraining limits.more » The elastic and momentum dependent limits remain robust for masses > or approx. 50 GeV under variations of the astrophysical parameters and the form of the velocity distribution.« less
  • In recent years, a number of experiments have been conducted with the goal of studying cosmic rays at GeV to TeV energies. This is a particularly interesting regime from the perspective of indirect dark matter detection. To draw reliable conclusions regarding dark matter from cosmic ray measurements, however, it is important to first understand the propagation of cosmic rays through the magnetic and radiation fields of the Milky Way. In this paper, we constrain the characteristics of the cosmic ray electron/positron propagation model through comparison with observational inputs, including recent data from the CREAM experiment, and use these constraints tomore » estimate the corresponding uncertainties in the spectrum of cosmic ray electrons and positrons from dark matter particles annihilating in the halo of the Milky Way.« less
  • We study the impact of the assumed velocity distribution of galactic dark matter particles on the interpretation of results from nuclear recoil detectors. By converting experimental data to variables that make the astrophysical unknowns explicit, different experiments can be compared without implicit assumptions concerning the dark matter halo. We extend this framework to include the annual modulation signal, as well as multiple target elements. Recent results from DAMA, CoGeNT and CRESST-II can be brought into agreement if the velocity distribution is very anisotropic and thus allows a large modulation fraction. However constraints from CDMS and XENON cannot be evaded bymore » appealing to such astrophysical uncertainties alone.« less
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