Excited Particle Physicists

Abbreviations. Violations. Sometimes science has everything.

Physicists have long suspected that a difference in the properties of matter and antimatter is key to the early universe’s survival. Such a difference—technically known as charge-parity (CP) violation—would have allowed normal matter to prevail over antimatter so that normal matter could go on to form all of the stuff we see in the universe today.

To witness CP violation, physicists study particles to see if there is any difference in the rate of decay between normal particles and their antiparticles. The accepted theory of elementary particles, the standard model, allows for a low level of CP violation—including that revealed in the discoveries of the 1960s and 2000s—but not enough to explain the prevalence of normal matter. So researchers have been trying to find cases in which CP violation is higher.

The LHCb detector at CERN, and CDF at Fermilab, are two such experiments. They trace the paths of D0 meson particles and their antiparticles. These can decay into pairs of either pions or kaons, and by tallying these decay products, the LHCb and CDF teams can calculate the difference in decay rates between the D0 particles and antiparticles.

The results cannot be claimed as a bona fide discovery, which requires a statistical significance of 5 sigma—or the chance of it being random at less than one in a million. Still, particle physicists are excited. “We cannot yet say for sure it is CP violation,” says Angelo Carbone, a member of the LHCb collaboration. “But it’s close.”

What have you done today to ensure the universe’s survival, huh?