Quantum Sensors May Unlock Secrets of Grand Unification and Ultra-Light Dark Matter

Physicists Xavier Calmet and Nathaniel Sherrill from the University of Sussex have proposed a method to investigate grand unification. This theory combines the three known gauge interactions into one force using quantum sensors. They suggest that scalar multiplets, mathematical objects used in quantum field theory, could provide a mechanism for a time-varying unified coupling, which could be probed with quantum sensors. The researchers also propose that these multiplets could represent ultra-light dark matter. This research could open new avenues for testing grand unified theories and understanding the universe.

Can Quantum Sensors Probe Grand Unification?

The concept of grand unification, a theory that seeks to unify the three known gauge interactions (the electromagnetic, weak, and strong forces) into one single force, has been a topic of interest in the field of physics. Xavier Calmet and Nathaniel Sherrill from the Department of Physics and Astronomy at the University of Sussex have proposed a method to probe grand unification using quantum sensors.

The researchers suggest that scalar multiplets, a type of mathematical object used in quantum field theory, coupled to the gauge sector of a grand unified theory, can provide a mechanism for a time-varying unified coupling. This time-varying unified coupling has low-energy consequences that can be probed with quantum sensors. The researchers also propose that these multiplets could represent ultra-light dark matter, a form of dark matter that is composed of particles that individually carry an extremely small amount of mass.

How Can Fundamental Constants Be Probed?

The stability of fundamental constants, such as the speed of light or the charge of an electron, has long been a topic of debate among scientists. Some theories of quantum gravity, which seek to reconcile quantum mechanics with general relativity, predict a cosmological time evolution of these constants.

Recent technological advancements in quantum sensors and atomic clocks have allowed for the testing of the stability of these constants with much improved precision. These advancements have led to new ideas on how to probe fundamental physics using quantum sensors. The researchers suggest that a time variation of these constants could enable us to probe grand unified theories at very low energy, without ever producing any of the heavy particles associated with such models.

What is the Role of Ultra-Light Dark Matter?

Ultra-light dark matter has been a topic of significant interest in recent years. The researchers propose a special case where the scalar multiplets, which are used to explain the time variation of the unified gauge coupling, are identified with ultra-light dark matter.

This work is the first attempt to embed this dark matter candidate in a grand unified theory. The researchers derive limits on the coupling between the scalar multiplet and standard model particles using data from atomic clock comparisons, pulsar timing arrays, NANOGrav, and MICROSCOPE.

How Can Time Variation of Fundamental Constants Be Achieved?

The researchers propose a mechanism for the time variation of fundamental constants within the context of grand unified theories. This mechanism involves a scalar multiplet charged under the grand unified theory group.

The researchers consider supersymmetric SU(5) as a unification group and assume that supersymmetry is broken at some low-energy scale and that unification takes place at some 10^16 GeV. They propose that the scalar multiplets are time-dependent classical background fields, which could lead to an effective time variation of the unified coupling constant.

What are the Implications of This Research?

This research provides a new perspective on how to probe grand unified theories and the stability of fundamental constants. The proposed mechanism involving scalar multiplets and quantum sensors could open up new avenues for testing these theories at low energies.

Furthermore, the identification of scalar multiplets with ultra-light dark matter could have significant implications for our understanding of the universe. This work represents a significant step forward in the ongoing quest to understand the fundamental forces of nature and the mysteries of dark matter.