Washington: A team of physicists has found the first direct evidence of pear shaped nuclei in exotic atoms.
The findings could advance the search for a new fundamental force in nature that could explain why the Big Bang created more matter than antimatter-a pivotal imbalance in the history of everything.
"If equal amounts of matter and antimatter were created at the Big Bang, everything would have annihilated, and there would be no galaxies, stars, planets or people," said Tim Chupp, a University of Michigan professor of physics and biomedical engineering.
Antimatter particles have the same mass but opposite charge from their matter counterparts. Antimatter is rare in the known universe, flitting briefly in and out of existence in cosmic rays, solar flares and particle accelerators like CERN`s Large Hadron Collider , for example. When they find each other, matter and antimatter particles mutually destruct or annihilate.
What caused the matter/antimatter imbalance is one of physics`great mysteries. It`s not predicted by the Standard Model-the overarching theory that describes the laws of nature and the nature of matter.
The Standard Model describes four fundamental forces or interactions that govern how matter behaves: Gravity attracts massive bodies to one another. The electromagnetic interaction gives rise to forces on electrically charged bodies. And the strong and weak forces operate in the cores of atoms, binding together neutrons and protons or causing those particles to decay.
Physicists have been searching for signs of a new force or interaction that might explain the matter-antimatter discrepancy. The evidence of its existence would be revealed by measuring how the axis of nuclei of the radioactive elements radon and radium line up with the spin.
The researchers confirmed that the cores of these atoms are shaped like pears, rather than the more typical spherical orange or elliptical watermelon profiles. The pear shape makes the effects of the new interaction much stronger and easier to detect.
"The pear shape is special. It means the neutrons and protons, which compose the nucleus, are in slightly different places along an internal axis," Chupp said.
The pear-shaped nuclei are lopsided because positive protons are pushed away from the center of the nucleus by nuclear forces, which are fundamentally different from spherically symmetric forces like gravity.
"The new interaction, whose effects we are studying does two things: It produces the matter/ antimatter asymmetry in the early universe and it aligns the direction of the spin and the charge axis in these pear-shaped nuclei," Chupp said.
The research was led by University of Liverpool Physics Professor Peter Butler.
"Our expectation is that the data from our nuclear physics experiments can be combined with the results from atomic trapping experiments measuring EDMs to make the most stringent tests of the Standard Model, the best theory we have for understanding the nature of the building blocks of the universe," the researcher said.