Thesis Prize Winner’s Calculations Characterize Neutrino Interactions

  • Photo of 2017 JSA Thesis Prize Winner Alessandro Baroni in a natural setting.

Alessandro Baroni was awarded the 2017 Jefferson Science Associates Thesis Prize. Photo: K. J. Soloria

Alessandro Baroni was awarded the 2017 JSA Thesis Prize for studying nuclear processes that contribute to scientists’ understanding of neutrinos.

NEWPORT NEWS, VA – Alessandro Baroni is helping demystify one of the most mysterious particles. His work is contributing to our understanding of neutrinos, and it has earned him the 2017 Jefferson Science Associates Thesis Prize for work performed on a thesis related to research at the Department of Energy’s Thomas Jefferson National Accelerator Facility.

Despite their abundance, neutrinos remain elusive. These chargeless, nearly massless particles are difficult to detect, because they rarely interact with other particles. However, a better understanding of neutrinos’ interactions could lead to insight into the evolution of the universe. 

Baroni approached the study of neutrinos differently: he studied neutrinos’ interactions with nuclei at low energy using chiral effective field theory. 

He started with quantum chromodynamics. QCD is the theory that describes the interaction that holds quarks together to form neutrons and protons, the particles that comprise nuclei. Baroni focused on studying processes that could be described with chiral effective field theory, a theory that allows physicists to get an approximate QCD calculation for interactions that provides a systematic method for reducing and estimating the uncertainties associated with approximation. 

“Chiral effective field theory has been proven to be a powerful tool in the description of low energy nuclear processes,” Baroni says. This tool allowed Baroni to model certain interactions of protons and neutrons with each other and with external probes, such as electrons and neutrinos. 

These dynamical interactions are responsible for many electroweak processes relevant to the neutrino experimental program, including neutrino interactions with nuclei and single- and double-beta decays. Baroni’s work has shown that such interactions can now be studied within the chiral effective field theory approach.

“The calculations, which combined the theoretical framework of chiral effective field theory with ab initio computational methods, led to numerical results in agreement with previous phenomenological calculations, that (in the past) have been important for the analysis of the data of the SNO experiment” he says. 

Baroni conducted the work in his thesis, titled “Nuclear Chiral Axial Currents and Applications to Few-Nucleon Systems,” at Thomas Jefferson National Accelerator Facility while pursuing his Ph.D. in theoretical nuclear physics at Old Dominion University. His thesis advisor was Rocco Schiavilla, a professor of physics at Old Dominion University and a senior staff member of Jefferson Lab’s Theory Center, a group with which Baroni also worked. 

In his thesis, Baroni focused on two nuclear processes: low energy neutrino deuteron scattering (when a neutrino interacts with a deuteron) and nuclear beta decay (when a neutron inside the nucleus converts into a proton, electron and antineutrino). Baroni used chiral effective field theory to derive and test nuclear axial currents, which are calculations that describe these processes. Because of Baroni’s work, these processes can now be studied using chiral effective field theory. 

The JSA Thesis Prize is awarded annually for the best Ph.D. student thesis on research related to Jefferson Lab science and includes a $2,500 cash award and a commemorative plaque. Nominations for the JSA Thesis Prize are judged on four criteria: the quality of the written work, the student's contribution to the research, the work's impact on the field of physics, and service (how the work benefits Jefferson Lab or other experiments).

“It is a great pleasure to receive this award,” Baroni says. “I would like to thank my advisor, Rocco Schiavilla, and the collaborators, Luca Girlanda, Alejandro Kievsky, Laura E. Marcucci, Saori Pastore and Michele Viviani, who made this work possible.”

Jerry Draayer, JSA CEO, presented the award to Baroni at the annual Jefferson Lab Users Group meeting, noting that, “It is important that JSA recognizes the work and contributions of our young researchers who are helping to define the future of our field.” 

Users are the scientists, from across the U.S. and worldwide, who conduct fundamental nuclear physics experiments with Jefferson Lab’s research facilities and capabilities. The Users Group Board of Directors oversees the award process. Baroni presented his work to the Users during a session at the meeting.

“As in previous years, the quality of theses nominated for the JSA thesis prize presented a challenge in selecting a winner,” said Krishna Kumar, chair of the Jefferson Lab Users Group Board of Directors and professor at Stony Brook University. “In the end, Alessandro Baroni’s thesis stood out.”

Baroni is currently a postdoctoral researcher at the University of South Carolina, where he continues to work in low energy theoretical nuclear physics. 

The JSA Thesis Prize was established in 1999 by the Southeastern Universities Research Association and is now one of many projects supported by the JSA Initiatives Fund Program, which was established by Jefferson Science Associates to support programs, initiatives and activities that further the scientific outreach, and promote the science, education and technology missions of Jefferson Lab in ways that complement its basic and applied research focus. Initiatives Fund awards are for those projects that benefit the lab user community and that leverage commitments of others.

Contact: Kandice Carter, Jefferson Lab Communications Office, 757-269-7263, kcarter@jlab.org

By Chris Patrick

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Jefferson Science Associates, LLC, a joint venture of the Southeastern Universities Research Association, Inc. and PAE Applied Technologies, manages and operates the Thomas Jefferson National Accelerator Facility, or Jefferson Lab, for the U.S. Department of Energy's Office of Science.DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.