Neutron stars do not reveal evidence of a fifth fundamental force

Neutron stars have failed to detect evidence of a hypothetical fifth fundamental force of nature. Researchers compared theoretical cooling rates of neutron stars with observational data, finding no indication of energy loss beyond known mechanisms. This suggests either the proposed particles do not exist or their interactions are weaker than predicted. The study, published in Physical Review Letters, narrows the possibilities for new physics but acknowledges uncertainties due to incomplete understanding of neutron star interiors.