United States scientists proposed that neutrons can decay into dark matter particles

Xinhua News Agency, Beijing, January 13 Xinhua As one of the most common basic particles, neutrons may have unusual dark secrets. The U.S. scientists recently proposed that neutrons will decay into dark matter particles. This neutron 'dark decay' Can explain the reason why the life expectancy of neutron 'can not be measured.'

The neutron trapped in the nucleus is very stable, but the free neutron has a life span of only about 15 minutes, which decays it to produce a proton, an electron and an anti-neutrino. Measuring the lifetime of free neutrons is two The main method, one is based on the decay product to infer, the other is the neutron bound in the container, counting the number of neutrons remaining after a specified time.

So far, there has always been a difference of about 8 seconds between the measurements of the two methods, with a calculated result of decay of about 888 seconds and a restraint in the container of 879.6 seconds.This is probably because There is systematic error, but it may also be due to an unknown way of decay of neutrons. Estimation of beta decay alone will give an estimation of neutron lifetime.

According to a recent report by the New Scientist magazine in the United States, two physicists at the University of California, San Diego, proposed that neutrons may decay into dark matter particles. One hundred decay times for a neutron is about one such 'dark decay' , Resulting in dark matter particle quality and neutron similar.

According to this new model, dark decay produces monochromatic photons and electron-positrons of specific energies, looking for these particles to test whether the theory is correct, and if supported by evidence, would be a major breakthrough in dark matter research; Aspects, determining the lifetime of free neutrons is also of great significance to physics.

According to the current model of the universe, we are familiar with only about 5% of the universe, and about another 27% is the 'dark matter' that basically does not interact with common matter except gravity, and about 68% is repulsive Not the 'dark energy' of gravitational attraction.For the nature of dark matter, the scientific community has come up with various assumptions, including some imaginary particles, such as massively weak interacting particles, axes, inert neutrinos, etc., but so far no exact Evidence supports any kind of theory.