Composite millicharged dark matter

Kouvaris, Chris

doi:10.1103/physrevd.88.015001

Cited by 17 publications

(14 citation statements)

References 88 publications

(132 reference statements)

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“…It is also possible that hidden sector contains millicharged fields, and this possibility also results in viable DM candidates[344] 7. Another possibility is to introduce a new electromagnetically charged scalar, so that the freeze-in production of sterile neutrinos occurs via decay of the charged scalar to a sterile neutrino and a charged SM lepton[346].…”

mentioning

confidence: 99%

The dawn of FIMP Dark Matter: A review of models and constraints

Bernal

Heikinheimo

Tenkanen

et al. 2017

Int. J. Mod. Phys. A

510

504

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Abstract. We present an overview of scenarios where the observed Dark Matter (DM) abundance consists of Feebly Interacting Massive Particles (FIMPs), produced non-thermally by the so-called freeze-in mechanism. In contrast to the usual freeze-out scenario, frozen-in FIMP DM interacts very weakly with the particles in the visible sector and never attained thermal equilibrium with the baryon-photon fluid in the early Universe. Instead of being determined by its annihilation strength, the DM abundance depends on the decay and annihilation strengths of particles in equilibrium with the baryon-photon fluid, as well as couplings in the DM sector. This makes frozen-in DM very difficult but not impossible to test. In this review, we present the freeze-in mechanism and its variations considered in the literature (dark freeze-out and reannihilation), compare them to the standard DM freeze-out scenario, discuss several aspects of model building, and pay particular attention to observational properties and general testability of such feebly interacting DM.

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mentioning

confidence: 99%

The dawn of FIMP Dark Matter: A review of models and constraints

Bernal

Heikinheimo

Tenkanen

et al. 2017

Int. J. Mod. Phys. A

510

504

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“…(4) However as we shall argue, if dark matter (DM) is in the form of millicharged particles (MC) (as for example [8], [9]), accretion of DM onto the NS can lead to an excess of electric charge that due to overall electric neutrality must be expelled from the caps, providing this way an extra component of current. On generic grounds, let us assume that the total current has two components, I = I GJ + I DM , where I DM represents the extra current due to external accretion from the MCDM galactic distribution where the NS may be located [10].…”

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confidence: 99%

Can dark matter explain the braking index of neutron stars?

Kouvaris

Pérez-García

2014

Phys. Rev. D

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We explore a new mechanism of slowing down the rotation of neutron stars via accretion of millicharged dark matter. We find that this mechanism yields pulsar braking indices that can be substantially smaller than the standard n ∼ 3 of the magnetic dipole radiation model for millicharged dark matter particles that are not excluded by existing experimental constraints thus accommodating existing observations. Preprint: CP 3 -Origins-2014-002 DNRF90 & DIAS-2014 Pulsar spin down has been studied since its discovery but yet to date, there is not a definite clear understanding for the handful of existing data values for rotationpowered pulsars [1]. The braking index n as defined from a spin down lawΩ ∼ Ω n , where Ω is the rotational angular velocity, is consistently smaller than the n = 3 value predicted for energy loss via pure dipole radiation. In order to explain this discrepancy other mechanisms have been invoked including relativistic particle flow, and inclination angles or reconnection in the magnetosphere (see e.g. the discussion in [2] and [3]). Apart from short lived glitches or eventual transitions to a more exotic quark star [4], the rate of rotation of a neutron star (NS) drops steadily as a function of time. The deceleration of the rotation is due to torques that are applied on the star impeding its motion. There are basically two components for the torque: an "orthogonal" one, that maximizes when the magnetic moment of the NS is perpendicular to the rotation axis of the star, and an "aligned" component, maximized when the rotation and the magnetic axis of the star are aligned. In the "orthogonal" case, angular momentum is lost through emission of magnetic dipole radiation. In the "aligned" case, the torque is produced by the electric current created by escaping charged particles (mainly electrons and protons) that follow the open field lines of the NS magnetosphere. The rotational kinetic energy loss rate for both mechanisms present is [5]where θ is the angle between the magnetic and the rotational axis. If we take M and R as the mass and radius of the NS respectively, the two components can be written aswhere B 0 is the magnetic field strength on the polar caps of the star, and Ω F = Ω − Ω death (Ω death being the angular velocity below which the pulsar emission dies). The current I is approximately equal to I GJ [6], whereC ρ GJ c is the current quoted in the pioneering work of Goldreich and Julian [7], representing the emission of relativistic charged particles with charge density ρ GJ , due to a large difference in the electrostatic potential, from the NS cap regions of a surface ∼ πR 2 C . ρ GJ is the electron density which shields the electric field and yields the only stable static solution for a pulsar magnetosphere (excluding centrifugal and gravitational forces). At the poles of the NS, it was estimated to be [7] ρ GJ ≃ 7 × 10 −2 e B 0 10 12 Gwhere P is the period of the pulsar. The field lines that do not close within the so-called light cylinder of the NS (defined as a cylinder of radius R ...

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“…In fact, we found that dispersion due to matter effects was irrelevant until energies around 10 29 GeV. But composite DM models might prove to be more reactive, particularly if the DM is comprised of charged constituents [29,30,35,37,42,44,45,47,48,50,52,53,58,59].…”

Section: Introductionmentioning

confidence: 88%

Optical dispersion of composite particles consisting of millicharged constituents

Kvam¹,

Latimer²

2016

J. Phys. G: Nucl. Part. Phys.

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Composite dark matter (DM) comprised of electrically charged constituents can interact with the electromagnetic field via the particle's dipole moment. This interaction results in a dispersive optical index of refraction for the DM medium. We compute this refractive index for atomic dark matter and more strongly bound systems, modeled via a harmonic oscillator potential. The dispersive nature of the index will result in a time lag between high and low energy photons simultaneously emitted from a distant astrophysical observable. This time lag, due to matter dispersion, could confound potential claims of Lorentz invariance violation (LIV) which can also result in such time lags. We compare the relative size of the two effects and determine that the dispersion due to DM is dwarfed by potential LIV effects for energies below the Planck scale.

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Composite millicharged dark matter

Cited by 17 publications

References 88 publications

The dawn of FIMP Dark Matter: A review of models and constraints

The dawn of FIMP Dark Matter: A review of models and constraints

Can dark matter explain the braking index of neutron stars?

Optical dispersion of composite particles consisting of millicharged constituents

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