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Title: From direct detection to relic abundance: the case of proton-philic spin-dependent inelastic Dark Matter

Abstract

We discuss strategies to make inferences on the thermal relic abundance of a Weakly Interacting Massive Particle (WIMP) when the same effective dimension-six operator that explains an experimental excess in direct detection is assumed to drive decoupling at freeze-out, and apply them to the explicit scenario of WIMP inelastic up-scattering with spin-dependent couplings to protons (proton-philic Spin-dependent Inelastic Dark Matter, pSIDM), a phenomenological set-up containing two Dark Matter (DM) particles χ{sub 1} and χ{sub 2} with masses m {sub χ}= m {sub χ{sub 1}} and m {sub χ{sub 2}}= m {sub χ}+δ that we have shown in a previous paper to explain the DAMA effect in compliance with the constraints from other detectors. We also update experimental constraints on pSIDM, extend the analysis to the most general spin-dependent momentum-dependent interactions allowed by non-relativistic Effective Field Theory (EFT), and consider for the WIMP velocity distribution in our Galaxy f ( v ) both a halo-independent approach and a standard Maxwellian. Under these conditions we find that the DAMA effect can be explained in terms of the particle χ{sub 1} in compliance with all the other constraints for all the analyzed EFT couplings and also for a Maxwellian f ( v ).more » As far as the relic abundance is concerned, we show that the problem of calculating it by using direct detection data to fix the model parameters is affected by a strong sensitivity on f ( v ) and by the degeneracy between the WIMP local density ρ{sub χ} and the WIMP-nucleon scattering cross section, since ρ{sub χ} must be rescaled with respect to the observed DM density in the neighborhood of the Sun when the calculated relic density Ω is smaller than the observed one Ω{sub 0}. As a consequence, a DM direct detection experiment is not directly sensitive to the physical cut-off scale of the EFT, but on some dimensional combination that does not depend on the actual value of Ω. However, such degeneracy can be used to develop a consistency test on the possibility that the WIMP is a thermal relic in the first place. When we apply it to the pSIDM scenario we find that only a WIMP with the standard spin-dependent interaction O=χ-bar {sub 1γ}{sup μ}γ{sup 5χ{sub 2}} q-bar γ{sub μ}γ{sup 5} q + h.c. with quarks can be a thermal relic for, approximately, 10 GeV\;≲ m {sub χ}≲ 16 GeV, 17 keV\;≲ δ≲ 28 keV, and a large uncertainty on Ω, 6× 10{sup −7}Ω{sub 0≲} Ω ≲ Ω{sub 0}. In order for the scenario to work the WIMP galactic velocity distribution must depart from a Maxwellian. Moreover, all the χ{sub 2} states must have already decayed today, and this requires some additional mechanism besides that provided by the O operator.« less

Authors:
;  [1]
  1. Department of Physics, Sogang University, Seoul (Korea, Republic of)
Publication Date:
OSTI Identifier:
22679910
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 04; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; CROSS SECTIONS; DECOUPLING; DENSITY; FIELD THEORIES; GALAXIES; GEV RANGE; INTERACTIONS; KEV RANGE; MASS; NONLUMINOUS MATTER; PARTICLE DECAY; PROTONS; QUARKS; RELATIVISTIC RANGE; SCATTERING; SPIN; SUN; VELOCITY; WIMPS

Citation Formats

Scopel, Stefano, and Yu, Hyeonhye, E-mail: scopel@sogang.ac.kr, E-mail: skyh2yu@gmail.com. From direct detection to relic abundance: the case of proton-philic spin-dependent inelastic Dark Matter. United States: N. p., 2017. Web. doi:10.1088/1475-7516/2017/04/031.
Scopel, Stefano, & Yu, Hyeonhye, E-mail: scopel@sogang.ac.kr, E-mail: skyh2yu@gmail.com. From direct detection to relic abundance: the case of proton-philic spin-dependent inelastic Dark Matter. United States. doi:10.1088/1475-7516/2017/04/031.
Scopel, Stefano, and Yu, Hyeonhye, E-mail: scopel@sogang.ac.kr, E-mail: skyh2yu@gmail.com. Sat . "From direct detection to relic abundance: the case of proton-philic spin-dependent inelastic Dark Matter". United States. doi:10.1088/1475-7516/2017/04/031.
@article{osti_22679910,
title = {From direct detection to relic abundance: the case of proton-philic spin-dependent inelastic Dark Matter},
author = {Scopel, Stefano and Yu, Hyeonhye, E-mail: scopel@sogang.ac.kr, E-mail: skyh2yu@gmail.com},
abstractNote = {We discuss strategies to make inferences on the thermal relic abundance of a Weakly Interacting Massive Particle (WIMP) when the same effective dimension-six operator that explains an experimental excess in direct detection is assumed to drive decoupling at freeze-out, and apply them to the explicit scenario of WIMP inelastic up-scattering with spin-dependent couplings to protons (proton-philic Spin-dependent Inelastic Dark Matter, pSIDM), a phenomenological set-up containing two Dark Matter (DM) particles χ{sub 1} and χ{sub 2} with masses m {sub χ}= m {sub χ{sub 1}} and m {sub χ{sub 2}}= m {sub χ}+δ that we have shown in a previous paper to explain the DAMA effect in compliance with the constraints from other detectors. We also update experimental constraints on pSIDM, extend the analysis to the most general spin-dependent momentum-dependent interactions allowed by non-relativistic Effective Field Theory (EFT), and consider for the WIMP velocity distribution in our Galaxy f ( v ) both a halo-independent approach and a standard Maxwellian. Under these conditions we find that the DAMA effect can be explained in terms of the particle χ{sub 1} in compliance with all the other constraints for all the analyzed EFT couplings and also for a Maxwellian f ( v ). As far as the relic abundance is concerned, we show that the problem of calculating it by using direct detection data to fix the model parameters is affected by a strong sensitivity on f ( v ) and by the degeneracy between the WIMP local density ρ{sub χ} and the WIMP-nucleon scattering cross section, since ρ{sub χ} must be rescaled with respect to the observed DM density in the neighborhood of the Sun when the calculated relic density Ω is smaller than the observed one Ω{sub 0}. As a consequence, a DM direct detection experiment is not directly sensitive to the physical cut-off scale of the EFT, but on some dimensional combination that does not depend on the actual value of Ω. However, such degeneracy can be used to develop a consistency test on the possibility that the WIMP is a thermal relic in the first place. When we apply it to the pSIDM scenario we find that only a WIMP with the standard spin-dependent interaction O=χ-bar {sub 1γ}{sup μ}γ{sup 5χ{sub 2}} q-bar γ{sub μ}γ{sup 5} q + h.c. with quarks can be a thermal relic for, approximately, 10 GeV\;≲ m {sub χ}≲ 16 GeV, 17 keV\;≲ δ≲ 28 keV, and a large uncertainty on Ω, 6× 10{sup −7}Ω{sub 0≲} Ω ≲ Ω{sub 0}. In order for the scenario to work the WIMP galactic velocity distribution must depart from a Maxwellian. Moreover, all the χ{sub 2} states must have already decayed today, and this requires some additional mechanism besides that provided by the O operator.},
doi = {10.1088/1475-7516/2017/04/031},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 04,
volume = 2017,
place = {United States},
year = {Sat Apr 01 00:00:00 EDT 2017},
month = {Sat Apr 01 00:00:00 EDT 2017}
}
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