Title: Luminous signals of inelastic dark matter in large detectors

Abstract

In this work, we study luminous dark matter signals in models with inelastic scattering. Dark matter $$\chi_1$$ that scatters inelastically off elements in the Earth is kicked into an excited state $$\chi_2$$ that can subsequently decay into a monoenergetic photon inside a detector. The photon signal exhibits large sidereal-daily modulation due to the daily rotation of the Earth and anisotropies in the problem: the dark matter wind comes from the direction of Cygnus due to the Sun's motion relative to the galaxy, and the rock overburden is anisotropic, as is the dark matter scattering angle. This allows outstanding separation of signal from backgrounds. We investigate the sensitivity of two classes of large underground detectors to this modulating photon line signal: large liquid scintillator neutrino experiments, including Borexino and JUNO, and the proposed large gaseous scintillator directional detection experiment CYGNUS. Borexino's (JUNO's) sensitivity exceeds the bounds from xenon experiments on inelastic nuclear recoil for mass splittings $$\delta \gtrsim 240 (180)$$ keV, and is the only probe of inelastic dark matter for $${350 \text{ keV} \lesssim \delta \lesssim 600 \text{ keV}}$$. CYGNUS's sensitivity is at least comparable to xenon experiments with $$\sim 10 \; {\rm m}^3$$ volume detector for $$\delta \lesssim 150$$ keV, and could be substantially better with larger volumes and improved background rejection. Such improvements lead to the unusual situation that the inelastic signal becomes the superior way to search for dark matter even if the elastic and inelastic scattering cross sections are comparable.

Authors:

Eby, Joshua ^[1]; Fox, Patrick J. ^[2]; Harnik, Roni ^[2]; Kribs, Graham D. ^[3]

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+ Show Author Affiliations

1. Weizmann Inst. of Science, Rehovot (Israel). Dept. of Particle Physics and Astrophysics
2. Fermilab, Batavia, IL (United States). Theoretical Physics Dept.
3. Univ. of Oregon, Eugene, OR (United States). Dept. of Physics

Publication Date:

2019-09-16

Research Org.:

Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)

OSTI Identifier:

1545092

Report Number(s):

arXiv:1904.09994; FERMILAB-PUB-19-147-T
Journal ID: ISSN 1029-8479; oai:inspirehep.net:1730850

Grant/Contract Number:  

AC02-07CH11359

Resource Type:

Accepted Manuscript

Journal Name:

Journal of High Energy Physics (Online)

Additional Journal Information:

Journal Name: Journal of High Energy Physics (Online); Journal Volume: 2019; Journal Issue: 9; Journal ID: ISSN 1029-8479

Publisher:

Springer Berlin

Country of Publication:

United States

Language:

English

Subject:

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Beyond Standard Model; cosmology of theories beyond the SM