Quantum decay through the looking glass

Imagine looking in the mirror and finding your familiar face reflected back as you've always known it. But as you look more closely, as you precisely examine that mirror image, subtle distortions emerge. The glass itself remains flawless, but real and fundamental differences exist between you and the face that lives on the other side of the looking glass.

Something similar happens in the quantum world when matter is examined against its exotic reflection: antimatter. The analogy is admittedly fanciful, but it's no more dramatic than the dynamics of these almost-twins, which annihilate one another on contact.

Elegance and simplicity suggest that during the Big Bang there were equal numbers of particles and antiparticles - a kind of balanced pure energy. But in reality, we live in a curiously lopsided universe, one in which matter reigns supreme. So what happened? Understanding the mechanism behind that cosmic preference remains one of the great puzzles in science, and physicists are closer than ever to tunneling through the looking glass to seek out the answers.

The distance scales incorporated into the kaon-decay calculation range from fractions of a meter (bubble-chamber image, bottom), to fractions of a femtometer (Fenyman diagram of quark transformations, top).

A new landmark calculation executed by an international team of physicists employed unparalleled experimental results and advanced supercomputers to reveal more about just how and why some fundamental symmetry breaks.

The collaboration examined the decay process of a kaon - the same particle explored in the 1964 experiment at Brookhaven Lab (winner of the 1980 Nobel Prize) that first revealed the charge-parity (CP) violation rooted in the asymmetry of matter and antimatter. Sometimes a perfectly balanced mixture of kaons and their antiparticles will decay unevenly, producing more matter than antimatter - therein lies the mystery.

The computational and experimental measurements spanned a combined 18 orders of magnitude - like considering a single bacterium within the scope of the entire solar system. To top that, particle decay is a prime example of quantum probability. That means that the calculations don't enjoy the luxury of certainty - Heisenberg removed that possibility back in 1927 - but with sophisticated predictions of possibilities.This new study applied the predictions of the Standard Model, the reigning theory that describes the behavior of fundamental particles, to actual experimental evidence. But the new calculation didn't come easily; in fact, it took 54 million computer processor hours.

So was the universe always uneven, or was it once a sea of uniform energy before some mechanism kicked in to throw antimatter under the bus? We're now closer to knowing, and this investigation will spur the next generation of supercomputers to take us even further.

For more on this important calculation, read the press release here.
The paper can be seen online in Physical Review Letters on March 30.

This post was written by Brookhaven Lab science writer Justin Eure.

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