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On the existence of low-mass dark matter and its direct detection.

Bateman J, McHardy I, Merle A, Morris TR, Ulbricht H - Sci Rep (2015)

Bottom Line: This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics.Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far.We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too.

View Article: PubMed Central - PubMed

Affiliation: Quantum, Light and Matter, Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom.

ABSTRACT
Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, gravitational lensing of light around these, and through its imprint on the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics. Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far. While its large interaction strength might at first seem unlikely, neither constraints from particle physics nor cosmological/astronomical observations are sufficient to rule out this type of DM, and it motivates our proposal for direct detection by optomechanics technology which should soon be within reach, namely, through the precise position measurement of a levitated mesoscopic particle which will be perturbed by elastic collisions with χ particles. We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too.

No MeSH data available.


Related in: MedlinePlus

(a), Acceleration of a silicon test particle (nucleon number density 1.4 · 1030 m−3) across the size regimes for χ de Broglie wavelength . For small particles (), the Born approximation holds and acceleration is proportional to nucleon number; for large particles (), the force is proportional to projected area and thus increases slower than the inertia. In the intermediate regime (), acceleration depends strongly upon the particle shape: for illustration we have chosen a spherical particle with an attractive interaction; the repulsive case is similar. Resonances, which distract from the main argument, have been smoothed by a few times their width. Similar plots are obtained for other de Broglie wavelengths, and the limiting cases are unaffected. (b), Reduction in sinusoidal fringe visibility due to elastic collisions for a range of mχ. Experiments with a similar geometry and path separation are indicated: state-of-the-art experiments have demonstrated 104 nucleons21; an experiment with 106 is proposed22; and space-based ‘MAQRO'23 will span the necessary range. For , the Born approximation for scattering χ particles is not well satisfied and further theoretical work is needed to fully describe the decoherence.
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f2: (a), Acceleration of a silicon test particle (nucleon number density 1.4 · 1030 m−3) across the size regimes for χ de Broglie wavelength . For small particles (), the Born approximation holds and acceleration is proportional to nucleon number; for large particles (), the force is proportional to projected area and thus increases slower than the inertia. In the intermediate regime (), acceleration depends strongly upon the particle shape: for illustration we have chosen a spherical particle with an attractive interaction; the repulsive case is similar. Resonances, which distract from the main argument, have been smoothed by a few times their width. Similar plots are obtained for other de Broglie wavelengths, and the limiting cases are unaffected. (b), Reduction in sinusoidal fringe visibility due to elastic collisions for a range of mχ. Experiments with a similar geometry and path separation are indicated: state-of-the-art experiments have demonstrated 104 nucleons21; an experiment with 106 is proposed22; and space-based ‘MAQRO'23 will span the necessary range. For , the Born approximation for scattering χ particles is not well satisfied and further theoretical work is needed to fully describe the decoherence.

Mentions: A consequence of the low χ mass is that the de Broglie wavelength is large compared to the internuclear separation in normal matter, . The χ hence scatters coherently from the constituent nuclei. For small particles under the Born approximation, all nuclei are subject to the same field from the incident χ, and we find an effective cross-section σeff = σN2. Conversely, for large particles, the flux is attenuated and the cross-section is the projected surface area σeff ∝ N2/3. In the intermediate regime, details of the interaction depend strongly on particle shape and on whether the underlying interaction is attractive or repulsive. For illustration, we consider a spherical particle with an attractive potential and we calculate the interaction via partial waves, described in further in the supplementary material; the expected acceleration a = σeffP/M, where M is the particle mass, as shown in FIG. 2 a, reduces to the Born approximation and to the geometrical approximation in the respective limits. Details of size-dependent acceleration in the intermediate regime, if observed, will allow for an independent measurement of the χ DM pressure P and collisional cross-section σ.


On the existence of low-mass dark matter and its direct detection.

Bateman J, McHardy I, Merle A, Morris TR, Ulbricht H - Sci Rep (2015)

(a), Acceleration of a silicon test particle (nucleon number density 1.4 · 1030 m−3) across the size regimes for χ de Broglie wavelength . For small particles (), the Born approximation holds and acceleration is proportional to nucleon number; for large particles (), the force is proportional to projected area and thus increases slower than the inertia. In the intermediate regime (), acceleration depends strongly upon the particle shape: for illustration we have chosen a spherical particle with an attractive interaction; the repulsive case is similar. Resonances, which distract from the main argument, have been smoothed by a few times their width. Similar plots are obtained for other de Broglie wavelengths, and the limiting cases are unaffected. (b), Reduction in sinusoidal fringe visibility due to elastic collisions for a range of mχ. Experiments with a similar geometry and path separation are indicated: state-of-the-art experiments have demonstrated 104 nucleons21; an experiment with 106 is proposed22; and space-based ‘MAQRO'23 will span the necessary range. For , the Born approximation for scattering χ particles is not well satisfied and further theoretical work is needed to fully describe the decoherence.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4306971&req=5

f2: (a), Acceleration of a silicon test particle (nucleon number density 1.4 · 1030 m−3) across the size regimes for χ de Broglie wavelength . For small particles (), the Born approximation holds and acceleration is proportional to nucleon number; for large particles (), the force is proportional to projected area and thus increases slower than the inertia. In the intermediate regime (), acceleration depends strongly upon the particle shape: for illustration we have chosen a spherical particle with an attractive interaction; the repulsive case is similar. Resonances, which distract from the main argument, have been smoothed by a few times their width. Similar plots are obtained for other de Broglie wavelengths, and the limiting cases are unaffected. (b), Reduction in sinusoidal fringe visibility due to elastic collisions for a range of mχ. Experiments with a similar geometry and path separation are indicated: state-of-the-art experiments have demonstrated 104 nucleons21; an experiment with 106 is proposed22; and space-based ‘MAQRO'23 will span the necessary range. For , the Born approximation for scattering χ particles is not well satisfied and further theoretical work is needed to fully describe the decoherence.
Mentions: A consequence of the low χ mass is that the de Broglie wavelength is large compared to the internuclear separation in normal matter, . The χ hence scatters coherently from the constituent nuclei. For small particles under the Born approximation, all nuclei are subject to the same field from the incident χ, and we find an effective cross-section σeff = σN2. Conversely, for large particles, the flux is attenuated and the cross-section is the projected surface area σeff ∝ N2/3. In the intermediate regime, details of the interaction depend strongly on particle shape and on whether the underlying interaction is attractive or repulsive. For illustration, we consider a spherical particle with an attractive potential and we calculate the interaction via partial waves, described in further in the supplementary material; the expected acceleration a = σeffP/M, where M is the particle mass, as shown in FIG. 2 a, reduces to the Born approximation and to the geometrical approximation in the respective limits. Details of size-dependent acceleration in the intermediate regime, if observed, will allow for an independent measurement of the χ DM pressure P and collisional cross-section σ.

Bottom Line: This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics.Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far.We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too.

View Article: PubMed Central - PubMed

Affiliation: Quantum, Light and Matter, Physics and Astronomy, University of Southampton, Southampton SO17 1BJ, United Kingdom.

ABSTRACT
Dark Matter (DM) is an elusive form of matter which has been postulated to explain astronomical observations through its gravitational effects on stars and galaxies, gravitational lensing of light around these, and through its imprint on the Cosmic Microwave Background (CMB). This indirect evidence implies that DM accounts for as much as 84.5% of all matter in our Universe, yet it has so far evaded all attempts at direct detection, leaving such confirmation and the consequent discovery of its nature as one of the biggest challenges in modern physics. Here we present a novel form of low-mass DM χ that would have been missed by all experiments so far. While its large interaction strength might at first seem unlikely, neither constraints from particle physics nor cosmological/astronomical observations are sufficient to rule out this type of DM, and it motivates our proposal for direct detection by optomechanics technology which should soon be within reach, namely, through the precise position measurement of a levitated mesoscopic particle which will be perturbed by elastic collisions with χ particles. We show that a recently proposed nanoparticle matter-wave interferometer, originally conceived for tests of the quantum superposition principle, is sensitive to these collisions, too.

No MeSH data available.


Related in: MedlinePlus