The subatomic particles are a mash-up of three lighter particles called quarks: two of the type known as up quarks and one down quark. But physicists have speculated for decades that protons may also host more massive quarks, called “intrinsic” are much heavier than up or down quarks. So heavy that, mind-bendingly, “you can have a component of the proton which is heavier than the proton itself,”
Physicists know that the more deeply you probe a proton, the more complicated it appears.
But charm quarks might exist inside protons even at low energies, in a more persistent, deep-seated form.
In quantum physics, particles don’t take on a definite state until they’re measured — they are instead described by probabilities. If protons contain intrinsic charm, there’d be a small probability to find within a proton not only two up quarks and a down quark, but also a charm quark and anti quark:the small probability means that the full mass of the charm quark and anti quark isn’t added to the proton’s heft, explaining how the proton may contain particles heavier than itself:using thousands of measurements from experiments at the LHC and other particle accelerators, combined with theoretical calculations, the team found evidence for intrinsic charm in the proton at a statistical level called 3 sigma:the intrinsic charm quarks carry about 0.6 percent of a proton’s momentum, the researchers report.
What’s more, defining what is meant by “intrinsic charm” isn’t straightforward, muddling the comparison of the new finding with earlier results from different groups. “Previous studies have found different limits on intrinsic charm partly because they have used different definitions and schemes,” says theoretical physicist Wally of Jefferson Lab in Newport News, Va, But Yuan has reservations about the type of calculation used to interpret the data:is not done at what we today call the state-of-art analysis:scientists need to pin down the proton’s intrinsic charm content to better understand results at the LHC and other facilities that smash protons together and observe what comes out. Researchers have to be able to gauge the ins and outs of the objects they’re colliding:data from future accelerators such as the planned Electron-Ion Collider could help, says theoretical physicist Tim Hobbs of Fermi lab in Batavia, Ill. For now, the proton remains mysterious. The problem is still with us; it remains very challenging. “Previous studies have found different limits on intrinsic charm partly because they have used different definitions and schemes,” There are six types, known as flavors, of quarks: up, down, charm, strange, top, and bottom.[4] Up and down quarks have the lowest masses of all quarks. The heavier quarks rapidly change into up and down quarks through a process of particle decay: the transformation from a higher mass state to a lower mass state. Because of this, up and down quarks are generally stable and the most common in the universe, whereas strange, charm, bottom, and top quarks can only be produced in high energy collisions (such as those involving cosmic rays and in particle accelerators).
Protons are commonly thought to contain only three quarks — two up quarks and one down quark (illustrated). But there’s new evidence that protons may also contain intrinsic charm quarks and anti quarks
This is the final report for the anti quarks and charm quarks
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