# Freddy Cachazo wins New Horizons Prize

“Perimeter is thrilled at this timely recognition of Freddy’s important work,” Director Neil Turok commented. “The techniques and concepts he introduced have shed new light on quantum field theory, our most basic description of reality, and have found immediate application in the analysis and interpretation of major international particle physics experiments. I believe his insights will have enduring impact in the search for a simpler, more unified description of nature’s physical laws.”

FPP prizes recognize theorists and researchers who are “dedicated to advancing our knowledge of the universe at the deepest level.” Although new, these awards are already considered highly prestigious.

It’s the second year in a row that a Perimeter faculty member has been tapped for a New Horizons Prize. Last year’s winners included quantum fields and strings researcher Davide Gaiotto.

This is the third major international prize for Cachazo. In 2011, he won the Rutherford Medal from the Royal Society of Canada. One of the Royal Society’s top honours, the medal recognizes outstanding research in any branch of physics. In 2009, Cachazo was awarded the Gribov Medal of the European Physical Society. Cachazo was also awarded the Herzberg Medal by the Canadian Association of Physicists in 2012.

In trying to understand nature’s most fundamental constituents, Cachazo has made several discoveries that have been widely characterized as breakthroughs.

He is best known for his work in developing new and much more user-friendly systems for calculating scattering amplitudes. Scattering amplitudes – which predict what happens when two or more particles interact – are the most fundamental calculation in particle physics. Unfortunately, calculating scattering amplitudes has, until now, been extremely difficult.

This has been a major stumbling block, particularly for high energy physics of the kind carried out at the Large Hadron Collider at CERN. In order to discover new phenomena at the LHC, it is necessary to first precisely calculate what current models predict – you can’t spot the unusual unless you know exactly what the usual looks like.

The standard way of doing these calculations has been to use Feynman diagrams. Using Feynman diagrams to model even simple collisions of a few particles can involve thousands of diagrams, each introducing many terms into the calculation. As collisions become more complex, the Feynman diagram technique becomes too unwieldy to use. The high energy physics of the LHC is now well beyond the reach of Feynman diagrams.

Cachazo’s work has helped to bring these calculations under better control. Drawing together ideas from quantum field theory and complex analysis, Cachazo and his collaborators developed new techniques that yield results far more simply and efficiently than was previously possible.

The new methods have had a significant impact on high energy physics. They have been adopted in state-of-the-art calculations used in the interpretation of new data coming from experiments at the Large Hadron Collider and other colliders.

Just this year, Cachazo and collaborators published a 152-page paper, walking the physics community through the elegant mathematical ideas behind a new system for calculating what happens when particles interact. The new system has created widespread excitement in the particle physics and mathematical physics communities. It will likely be a focal point for years to come.

Cachazo has also done work untangling the difficult knot of calculating the scattering amplitudes of gravitons. A graviton is a hypothetical particle that carries the force of gravity, in the same way photons carry the electromagnetic force. Gravitons are more complicated than photons, though; every graviton carries a great deal of information.

This dense tangle of information means that the calculation of scattering amplitudes for even the simplest process – where two gravitons scatter off each other and produce more – has always been intractable. In 2012, Cachazo and collaborator David Skinner found a new way of organizing the mathematics, which made it possible to write down a general formula for graviton-graviton scattering for the first time.

These discoveries of new and surprising mathematical structures governing scattering amplitudes are of immediate utility to experimentalists, but they may also have deeper implications. In physics, it is often the case that when the results of calculations are much simpler than expected, then there is some principle or symmetry that is revealed. Cachazo’s work has initiated a profound shift in our understanding of quantum field theories. It may provide clues that will lead to a much deeper understanding of how elementary particles arise and the structure of spacetime itself.

Perimeter is also delighted that one of its Distinguished Visiting Research Chairs, Andrew Strominger, of Harvard University, has won one of three Physics Frontiers Prizes (with his collaborator, Cumrun Vafa, also at Harvard) and has become a candidate for the $3 million Fundamental Physics Prize.

### ABOUT THE FUNDAMENTAL PHYSICS PRIZE FOUNDATION

The Fundamental Physics Prize Foundation is a not-for-profit corporation dedicated to advancing our knowledge of the universe at the deepest level by awarding annual prizes for scientific breakthroughs, as well as communicating the excitement of fundamental physics to the public. Two categories of prizes are awarded for achievements in the field of fundamental physics: the Fundamental Physics Prize, which recognizes transformative advances in the field, and the New Horizons in Physics Prizes, which are targeted at promising junior researchers.

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