Professor’s Paper of the Week shows evolution of particle physics
by Emily Ashbolt, Biomedical Physics, 2017
A recent paper by Pran Nath, Distinguished Professor of Physics, was chosen as Paper of the Week on Physica Scripta, Journal of the Royal Swedish Academy of Sciences. It documents the great physics breakthroughs he and the physicists he worked with have made over the past 50 years while at Northeastern University. Nath has been a prolific researcher with over 400 papers in this period. However, his paper in Physica Scripta in particular captures the mind and the imagination of the reader in a way that shows how the field of particle physics has evolved over the past decades and how his own work was transformational in the evolution of the field.
In fact, looking back at his long and prolific career, Nath can easily reference the top moments that were transformational. “I would say there are three pivotal points in my career,” Nath explained. “I arrived [at Northeastern] in 1966 as an assistant professor, and very shortly after that, I started working on a project with colleagues that lead to a breakthrough. We developed a new Lagrangian approach to the study of physics of mesons and this approach continues to be valid several decades later.”
A lot of Nath’s stories could be told that way. The second breakthrough of his work came when he and his colleague, the late Richard Arnowitt, extended the theory of supersymmetry by bringing in gravity, which other scientists eventually developed into string theory.
The third breakthrough, arguably his magnum opus, was in helping create the Minimal Supergravity model known as mSUGRA, which joins the fields of supersymmetry, gravity and particle physics. The mSUGRA model predicts a host of new particles popularly known as superparticles. It is one of the most widely investigated models of particle physics and is currently continuing to be explored at the Large Hadron Collider—the world’s largest and most powerful particle accelerator, located in Geneva, Switzerland.
Superparticles have not been seen so far, but this is due to the high scale of energy required to see them, according to Nath. “It’s quite simple—we just haven’t reached the level of energy to see them.” According to the work Nath and his group have done, the discovery of the Higgs boson in 2012 at a mass higher than expected requires the superparticle mass to be high, which in turn requires the energy of the particle physics accelerators to be rather large to see them.
Nath explains that the biggest barrier to the exploration of new particle physics is ultimately the highest energy scale physicists can achieve in the laboratory. There could be a whole slew of new physics out there that we currently cannot reach because the energy scale is not high enough. But our ability to increase reachable energy scales has increased exponentially since the 1950s, and Nath, along with other scientists working in this field, have been there to shepherd much of the new science through this period.
Nath’s work has contributed significantly to a revolution in the way that particle physics was seen by the world. By the mid-60s, scientists were beginning to realize that particle physics known up to that point just was not enough to explain all the various and new phenomena around them. The development of new particle accelerators and advanced mechanisms for particle detection allowed for new physics to be explored at higher and higher energies, and the push to advance to ever higher energies isn’t slowing down anytime soon. This gives hope to Nath that his work will continue to be utilized in the exploration of new physics at larger particle accelerators in the future.
Nath started his research at Northeastern in the mid-‘60s. In the 50 years since, both Nath and the scientific community have seen the limits of what is possible tested by leaps and bounds. While, as Nath explains, our current knowledge of the Universe is incomplete, there is no denying the impact of the work he has done to try and rectify this problem.