Proton contains more anti-down quarks than anti-up quarks

Recommendable! Let's see whether this result will be confirmed by other experiments!

"The sea of short-lived particles in the proton has a far higher abundance of anti-down quarks than anti-up quarks, new research has shown. ...
Instead, the proton is now modelled as a roiling “sea” of many quarks, antiquarks and gluons that pop in and out of existence over very short time scales. ...
Several theories had suggested that these seas should contain near-identical probability distributions of anti-up and anti-down quarks. ...
Contrary to previous predictions, the researchers found that over a wide range of collision momenta, protons contain a far higher abundance of anti-down quarks than anti-up. ..."

"... An essential feature of this [strong] force, as described by quantum chromodynamics, is its ability to create matter–antimatter quark pairs inside the proton that exist only for a very short time. Their fleeting existence makes the antimatter quarks within protons difficult to study, but their existence is discernible in reactions in which a matter–antimatter quark pair annihilates. ... Here we provide evidence from muon pair production measurements that these distributions are considerably different, with more abundant down antimatter quarks than up antimatter quarks over a wide range of momenta. ..."

Proton contains more anti-down quarks than anti-up – Physics World

Here is the link to the underlying research paper:

The asymmetry of antimatter in the proton (Behind paywall. However, the above Physics World article provides a link to the PDF file)