Darkish Matter May Be Hiding in Current Information From Present Detectors

Dark Matter Lurking Concept

Present experiments’ detectors and knowledge evaluation efforts might be refocused to hunt out newly advised sorts of darkish matter alerts which will have been missed.

Darkish matter has to date defied each sort of detector designed to seek out it. Due to its big gravitational footprint in area, we all know darkish matter should make up about 85 p.c of the overall mass of the universe, however we don’t but know what it’s product of.

A number of giant experiments that hunt for darkish matter have looked for indicators of darkish matter particles knocking into atomic nuclei by way of a course of generally known as scattering, which may produce tiny flashes of sunshine and different alerts in these interactions.

Now a brand new examine, led by researchers on the Division of Power’s Lawrence Berkeley Nationwide Laboratory (Berkeley Lab) and UC Berkeley, suggests new paths for catching the alerts of darkish matter particles which have their power absorbed by these nuclei.

The absorption course of may give an affected atom a kick that causes it to eject a lighter, energized particle equivalent to an electron, and it would produce different sorts of alerts, too, relying on the character of the darkish matter particle.

Evolution of Dark Matter Universe

This picture was produced by a simulation exhibiting the evolution of darkish matter within the universe. Credit score: Milennium-II Simulation

The examine focuses totally on these circumstances the place an electron or neutrino is ejected because the darkish matter particle strikes an atom’s nucleus.

Revealed on Might 4, 2020, in Bodily Evaluation Letters, the examine proposes that some present experiments, together with ones that seek for darkish matter particles and processes associated to neutrinos – ghostly, detectable particles that may go via most matter and have the power to alter into completely different types – can simply be broadened to additionally search for these absorption-related sorts of telltale darkish matter alerts.

Additionally, the researchers suggest that new searches in beforehand collected particle detector knowledge may presumably flip up these missed darkish matter alerts.

“In this field, we’ve had a certain idea in mind about well-motivated candidates for dark matter, such as the WIMP,” or weakly interacting huge particle, stated Jeff Dror, the lead writer of the examine who’s a postdoctoral researcher in Berkeley Lab’s Concept Group and UC Berkeley’s Berkeley Middle for Theoretical Physics.

Photomultiplier Tube Arrays WIMP-Hunting LUX-ZEPLIN

Photomultiplier tube arrays are ready for the WIMP-hunting LUX-ZEPLIN experiment throughout meeting on the Sanford Underground Analysis Facility in Lead, South Dakota. Credit score: Matt Kapust/SURF

Darkish matter pushes on the boundaries of the identified basic legal guidelines of physics, encapsulated within the Commonplace Mannequin of particle physics, and “The WIMP paradigm is very easy to build into the Standard Model, but we haven’t found it for a long time,” Dror famous.

So, physicists are actually contemplating different locations that darkish matter particles could also be hiding, and different particle prospects equivalent to theorized “sterile neutrinos” that is also introduced into the household of particles generally known as fermions – which incorporates electrons, protons, and neutrinos.

“It’s easy, with small modifications to the WIMP paradigm, to accommodate a whole different type of signal,” Dror stated. “You can make a huge amount of progress with very little cost if you step back a little bit in the way we’ve been thinking about dark matter.”

Robert McGehee, a UC Berkeley graduate scholar, and Gilly Elor of the College of Washington had been examine co-authors.

The researchers observe that the vary of recent alerts they’re specializing in opens up an “ocean” of darkish matter particle prospects: particularly as-yet-undiscovered fermions with lots lighter than the standard vary thought-about for WIMPs. They might be shut cousins of sterile neutrinos, for instance.

The examine staff thought-about absorption processes generally known as “neutral current,” by which nuclei within the detector materials recoil, or get jolted by their collision with darkish matter particles, producing distinct power signatures that may be picked up by the detector; and likewise these generally known as “charged current,” which may produce a number of alerts as a darkish matter particle strikes a nucleus, inflicting a recoil and the ejection of an electron.

The cost present course of also can contain nuclear decay, by which different particles are ejected from a nucleus as a form of domino impact triggered by the darkish matter absorption.

Reference: “Directly Detecting Signals from Absorption of Fermionic Dark Matter” by Jeff A. Dror, Gilly Elor and Robert McGeheen, 4 Might 2020, Bodily Evaluation Letters.
DOI: 10.1103/PhysRevLett.124.181301

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