https://phys.org/news/2020-02-universe.html
Why is there any matter in the universe at all?
New study sheds light:
Scientists at the University of Sussex have measured a property of the neutron—a fundamental particle in the universe—more precisely than ever before. Their research is part of an investigation into why there is matter left over in the universe, that is, why all the antimatter created in the Big Bang didn't just cancel out the matter.
The team—which included the Science and Technology Facilities Council's (STFC) Rutherford Appleton Laboratory in the UK, the Paul Scherrer Institute (PSI) in Switzerland, and a number of other institutions—was looking into whether or not the neutron acts like an "electric compass." Neutrons are believed to be slightly asymmetrical in shape, being slightly positive at one end and slightly negative at the other—a bit like the electrical equivalent of a bar magnet. This is the so-called "electric dipole moment" (EDM), and is what the team was looking for.
more at link....
the paper:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.081803
Measurement of the Permanent Electric Dipole Moment of the Neutron:
ABSTRACT:
We present the result of an experiment to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute using Ramsey’s method of separated oscillating magnetic fields with ultracold neutrons. Our measurement stands in the long history of EDM experiments probing physics violating time-reversal invariance. The salient features of this experiment were the use of a 199Hg comagnetometer and an array of optically pumped cesium vapor magnetometers to cancel and correct for magnetic-field changes. The statistical analysis was performed on blinded datasets by two separate groups, while the estimation of systematic effects profited from an unprecedented knowledge of the magnetic field. The measured value of the neutron EDM is dn=(0.0±1.1stat±0.2sys)×10−26e.cm.
Why is there any matter in the universe at all?
New study sheds light:
Scientists at the University of Sussex have measured a property of the neutron—a fundamental particle in the universe—more precisely than ever before. Their research is part of an investigation into why there is matter left over in the universe, that is, why all the antimatter created in the Big Bang didn't just cancel out the matter.
The team—which included the Science and Technology Facilities Council's (STFC) Rutherford Appleton Laboratory in the UK, the Paul Scherrer Institute (PSI) in Switzerland, and a number of other institutions—was looking into whether or not the neutron acts like an "electric compass." Neutrons are believed to be slightly asymmetrical in shape, being slightly positive at one end and slightly negative at the other—a bit like the electrical equivalent of a bar magnet. This is the so-called "electric dipole moment" (EDM), and is what the team was looking for.
more at link....
the paper:
https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.081803
Measurement of the Permanent Electric Dipole Moment of the Neutron:
ABSTRACT:
We present the result of an experiment to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute using Ramsey’s method of separated oscillating magnetic fields with ultracold neutrons. Our measurement stands in the long history of EDM experiments probing physics violating time-reversal invariance. The salient features of this experiment were the use of a 199Hg comagnetometer and an array of optically pumped cesium vapor magnetometers to cancel and correct for magnetic-field changes. The statistical analysis was performed on blinded datasets by two separate groups, while the estimation of systematic effects profited from an unprecedented knowledge of the magnetic field. The measured value of the neutron EDM is dn=(0.0±1.1stat±0.2sys)×10−26e.cm.