Dr. Shikma Bressler is refining nature’s laws

When the media headlines on July 4, 2012, revealed triumphantly that the once-elusive Higgs boson particle had been found, the thousands of physicists who had been working for decades on this puzzle didn’t pack their bags, call it a day, and go home.

On the contrary. The finding opened the door to reams of new research on the fundamental building blocks of our universe. Dr. Shikma Bressler, who has been an active member of the ATLAS collaboration at the Large Hardron Collider (LHC) at CERN, where the particle was discovered, is one scientist who is leveraging the new knowledge to hammer out an ever-clearer understanding of the laws of nature. She was hired as a new principal investigator at the Weizmann Institute this year in the Department of Particle Physics and Astrophysics, after having joined in 2013 at the rank of scientist.

The discovery of the Higgs boson is a cornerstone in the so-called Standard Model of particle physics—our best understanding of matter at its most fundamental level. But it certainly did not solve all the mysteries in the field of particle physics.

Physicists agree that the Standard Model fails to explain certain phenomena such as gravity, or the origin of neutrinos’ mass, or the “dark matter” that helps explain the rotation of galaxies. These shortcomings indicate that the Standard Model is not a complete theory of nature, suggesting there is more to discover. “By using insights from the ATLAS experiment, I am especially interested in finding evidence for physics beyond the Standard Model,” says Dr. Bressler.

Many models extending the Standard Model have been developed. The LHC searches for signatures predicted by these models. In particular, the ATLAS experiment was designed to exploit the discovery potential of the LHC. Dr. Bressler is leading a multinational team at CERN searching for so-called “lepton flavor violating decays” of the Higgs boson. Three types (flavors) of lepton—an elementary particle—are known. The most familiar is the electron, which is the lightest one, but there are also the muon and tau leptons. These differ from the electron only by their mass. The three lepton flavors carry the same electric charge and interact with the other fundamental particles in exactly the same way.

Within the Standard Model—the current theory describing very precisely the elementary particles and their interactions—the Higgs can decay only to a pair of same-flavor leptons, for instance a tau lepton and an anti-tau lepton. A decay of the Higgs into a tau lepton and an anti-muon would violate the lepton flavor number and thereby would contradict the Standard Model. Finding such decays would revolutionize our understanding of the fundamental laws of nature.

In parallel to the analysis of the data collected by the ATLAS experiment and in preparation for future challenges, Dr. Bressler formed a detector development team at the Weizmann Institute which develops novel detection concepts for large-size radiation-imaging detectors. Such detectors could improve the detection techniques currently used in particle physics experiments. While this line of work is motivated by a desire to understand the fundamental elements of the universe, it has potential for non-scientific applications in homeland security, medicine, archaeology, volcanology and more. In all these fields, radiation detectors can be used as an imaging system and identify, for instance, hazardous material in civil cargo, tumor surrounded by a healthy tissue, an ancient building underground. 

Dr. Bressler was raised in the Jezreel Valley, where she lives today. She completed her BSc summa cum laude in physics and mathematics at the Technion – Israel Institute of Technology in 2003, followed by her MSc there cum laude in physics in 2006 and PhD in 2011. In 2012, she joined the Weizmann Institute as a postdoctoral fellow. In 2013 she joined the Institute as a Scientist and formed a particle physics and detector development team, and in 2015 was promoted to Senior Scientist.

Image copyright: ATLAS Experiment © 2014 CERN 

Atlas experiment