SLAC’s planned project, the Light-Dark Matter Experiment (LDMX), will scan for light-dark matter if it receives funding (a Department of Energy decision is expected in the next year or so). The experiment is designed to accelerate electrons toward a tungsten target at End Station A. In the vast majority of collisions between high-speed electrons and tungsten nuclei, nothing interesting happens. But occasionally (once in 10,000 trillion, if light-dark matter exists), the electron will interact with the nucleus through an unknown dark force, creating light-dark matter and draining the electron’s energy considerably.
The 10,000 trillion is actually a worst-case scenario for light dark matter. It’s the lowest rate at which dark matter could be produced that matches the thermal remnant measurements. But Schuster says that light dark matter could potentially occur in more than one collision in 100 billion. If so, at the experiment’s planned collision speed, “the amount of dark matter that could be produced would be enormous.”
Nelson said LDMX needs to operate for three to five years to definitively detect or rule out thermal remnant dark matter.
Ultralight Dark Matter
Other dark matter hunters are tailoring their experiments to a different candidate. Ultralight dark matter is similar to axions, but it no longer needs to solve the strong CP problem. For this reason, it is much lighter than a normal axion, and could be as light as a billionth of a trillionth of the mass of an electron. This small mass corresponds to waves with wavelengths as long as a small galaxy. In fact, the mass cannot be made any smaller, because if it were to get smaller, the even longer wavelengths would mean that dark matter could not be concentrated around galaxies as astronomers observe.
Because ultralight dark matter is so incredibly tiny, the dark force particles needed to mediate its interactions are thought to be massive. “These mediators haven’t been named,” Schuster says, “because they’re outside the scope of any experiment. They have to be there.” [in the theory] To be consistent, we’re not worried about that.”
The origin of ultralight dark matter particles depends on the particular theoretical model, but Toro says that the thermal residue theory is irrelevant because they must have arisen after the Big Bang. The motivation for thinking about them is different: the particles follow naturally from string theory, a candidate for the fundamental theory of physics. These weak particles are Six Small Dimensions According to string theory, it is possible that at various points in the four-dimensional universe, light axion-like particles may be curling up or “compactifying.” “The existence of light axion-like particles is Strong motivation “This is something that gets achieved through many kinds of string compactification, and it’s something that we should take seriously,” said Jesse Shelton, a physicist at the University of Illinois.
Rather than trying to create dark matter using accelerators, experiments looking for axions, or ultralight dark matter, listen to the dark matter that supposedly surrounds us. Based on the effects of gravity, dark matter appears to be most concentrated near the center of the Milky Way galaxy. estimate Even on Earth, the density of dark matter is thought to be roughly half the mass of a proton per cubic centimeter. Experiments attempt to detect this ever-present dark matter using strong magnetic fields. In theory, the dark matter in the aether will occasionally absorb photons from the strong magnetic field and convert them into microwave photons that can be detected by experiments.