Standard model: proton weight may be smaller (Introduction)

by David Turell , Thursday, July 06, 2017, 20:36 (2674 days ago) @ David Turell

Protons are in all atoms. a lighter weight may explain why antimatter is so sparse:

https://www.newscientist.com/article/2139372-protons-are-lighter-than-thought-which-may...

"The proton has lost a little of its bulk. A fresh attempt to pin down its mass, with three times the precision of the previous best try, finds that the subatomic particle is 30 billionths of a per cent lighter than we thought.

"All atoms contain at least one proton, which means measurements of its simplest characteristics – its size, charge and mass – can help answer some of the big questions in physics, including why the universe contains more matter than antimatter.

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"The slimming down of the proton could help us fine-tune experiments that aim to understand why the amount of matter in the universe dwarfs the amount of antimatter, says Makoto Fujiwara, who works on CERN’s ALPHA experiment, seeking differences between hydrogen and its antimatter counterpart.

"More precise measurements on the proton will allow researchers to look for smaller discrepancies between it and the antiproton, although Fujiwara points out similar precision in antiproton measurements will be needed for that.

As for the tiny discrepancy between the new proton mass and the previously reported value, “in precision measurement, this is not so unusual”, Sturm says.

"But no one is yet sure why the results disagree. It could be an indication of new physics – or simply an experimental error that the researchers overlooked, Mohr says. “Of course, 99 percent of the time, it’s an experimental issue,” he says. “We don’t break through new principles that often.”

"Sturm’s group produced its measurement in time for CODATA’s latest physics standards, which will be published in a few months. Since we don’t know why this measurement differs from the last, CODATA has to carefully consider how to make use of the new value, Mohr says.

"Sturm’s group plans to repeat and refine the measurement. “We will try to implement some new techniques which should improve the precision by a factor of six,” he says."

Comment: the small amount of antimatter is not well explained.