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OSG council member Stefan Höche receives IUPAP Young Scientist Prize

The International Union of Pure and Applied Physics (IUPAP) awarded a 2016 Young Scientist Prize in Particles and Fields to Stefan Höche, a particle physicist at SLAC National Accelerator Laboratory and an Open Science Grid (OSG) council member, for “developing high precision Monte Carlo simulations of events at hadronic colliders.”

 

Stefan Hoeche at SLAC

Stefan Hoeche at SLAC


For an OSG research highlight in 2014, Höche described his work this way:

Two cars collide on the motorway. It happens so fast that we cannot see details. From debris that is scattered around the scene we try to reconstruct interesting facts: Did the driver wear a seatbelt? Did the airbag work? What happened to the purse in the glove compartment?

Now imagine doing this for collisions that happen more than once every millisecond, i.e., a thousand times per second. We are talking about the Large Hadron Collider in Geneva. It smashes protons at nearly the speed of light. They behave much like a car and disintegrate. Physicists study the debris to reveal which forces were at work, and find the fundamental theory of nature.

More precise simulations mean better analysis of hadron collider data like that from the LHC, which in turn brings us closer to understanding nature at the most fundamental level. That is why Höche and his colleagues develop computer programs like Sherpa for calculating the dynamics of particle collisions at unprecedented accuracy.

Most of Höche’s work is concerned with the strong interactions (the forces which hold together the subatomic particles of a nucleus). These forces can be described by the theory of Quantum Chromodynamics (QCD), a complex theory that makes exact predictions for LHC events almost impossible. Particle physicists use approximations to tackle the problem, but the better their approximations, the higher the computing costs.

 

 


Making precise calculations efficient on today’s computers is one of the common challenges Höche and his colleagues face day to day. Another is finding new algorithms to improve their approximations to the full theory of QCD. Above: Representation of a proton-proton collision. Image credit: Frank Krauss/Durham University. Used with permission.

Making precise calculations efficient on today’s computers is one of the common challenges Höche and his colleagues face day to day. Another is finding new algorithms to improve their approximations to the full theory of QCD. Above: Representation of a proton-proton collision. Image credit: Frank Krauss/Durham University. Used with permission.



 

To support this work, Höche received an Early Career Research Program grant from the U.S. Department of Energy (DOE) in 2013. He was one of 61 scientists selected for the award, among them three from his home institution, the SLAC National Accelerator Laboratory. Höche is an active user of the OSG, though he is currently focused on the improvement and extension of his software to tackle more complex calculations. The IUPAP award highlighted his achievements this way:

His professional career has been devoted to providing more accurate simulations of the complex scattering events that take place when two high energy hadrons collide, such as at the Large Hadron Collider. Such simulations are essential to experimentalists for precision measurements of Higgs boson couplings as well as in the search for new physics. He has produced simulations that are accurate to next-to-next-to-leading order in the strong coupling constant for benchmark processes such as Higgs production and W and Z boson production. He has also shown how to construct simulations that are accurate to next-to-leading order, even for events with additional jets within the same sample. He recently developed a novel parton shower formalism which has significantly improved behavior compared with previous ones. His work sets the standards for the precision calculations and simulation tools used at the LHC today.

Established in 1922 in Brussels with 13 member countries, IUPAP is dedicated to the worldwide development of physics. Its first general assembly was held in 1923 in Paris and it currently has 60 member countries. Each year, IUPAP sponsors a number of awards for scientists, including the Young Scientist Prize, which is granted by IUPAP Commissions to candidates who have up to 8 years of research experience following a Ph.D.

– Greg Moore