Lepton Flavor Universality Tests Using Bc+ Decays at LHCb

UMD graduate student Emily Jiang delivered a CERN seminar on May 19, 2026, unveiling an important new result on studies of Lepton Flavor Universality using decays of the heaviest B meson, Bc+, which has quark contents of a bottom-quark and anti-charm quark.   

The result is primarily the work of Jiang, UMD alumnus Zishuo Yang (Ph.D., 2023), Phoebe Hamilton and Hassan Jawahery, members of the Large Hadron Collider beauty experiment (LHCb) at CERN in Geneva, Switzerland.  It was a seven-year effort undertaken while the UMD group was also working on the development and construction of the new LHCb detector.LHCbLHCb

These results are of significant interest in the field because they show deviation from the Standard Model predictions. Previous measurements of similar quantities using the light B mesons from the BaBar experiment at SLAC, Belle Experiment at the KEK laboratory in Japan and the LHCb experiment at CERN are also in tension with the Standard Model. The new results show a similar trend, reinforcing the effect and has been highly anticipated in the field.

Jiang’s presentation can be seen here: https://indico.cern.ch/event/1685950/attachments/3277204/5855756/26-04-23_ejiang_CERN_seminar.pdf

For further information:

https://bolek.web.cern.ch/RJpsi/

https://lhcb-outreach.web.cern.ch/2026/05/19/lepton-flavor-universality-tests-using-bc-decays-at-lhcb/

Childhood Physics Fun Leads to Twin PhDs

When Sylvester James Gates III (B.S. ’15, biological sciences) graduates from the University of Maryland with his Ph.D. in biological sciences this month, it will be a family affair—and a homecoming. 

Sylvester grew up near College Park. His father, Distinguished University Professor of Physics Sylvester James Gates Jr., who goes by Jim, holds the Clark Leadership Chair in Science and has been at UMD since 1984. As kids, Sylvester and his twin, Delilah Gates (B.S. ’15, physics; B.S. ’15, mathematics), spent their free days with their dad in the John S. Toll Physics BuildingThe Gates family after Sylvester's graduation. From left: Sylvester James Gates Jr., Sylvester James Gates III, Delilah Gates, Dianna Abney. Photo courtesy of Sylvester James Gates III.The Gates family after Sylvester's graduation. From left: Sylvester James Gates Jr., Sylvester James Gates III, Delilah Gates, Dianna Abney. Photo courtesy of Sylvester James Gates III.

“The university always felt like a second home to me,” Sylvester said. 

So it was no surprise that both twins chose to stay in College Park for their bachelor’s degrees and they both became scientists. 

After graduating from UMD, Delilah earned her Ph.D. in physics from Harvard University in 2021, where she studied black holes in space. She completed a Future Faculty in the Physical Sciences Fellowship at Princeton University and then returned to Harvard as a postdoctoral fellow at the Center for Astrophysics | Harvard & Smithsonian and a member of the Black Hole Initiative. 

Sylvester, meanwhile, spent a brief stint in graduate school at Duke University before returning to Maryland for his Ph.D., where he studied how brain cells communicate. Working with Physics Professor Wolfgang Losert, Sylvester’s Ph.D. research developed new, nontraditional ways to measure brain cell activity—for example, by monitoring ions, stress compounds and the cell’s internal skeleton. He argues that gaining a more holistic picture of how the brain works could lead to more powerful artificial neural networks for computing and better drug discovery for brain diseases. 

When Sylvester presented this work during his dissertation defense in April, his whole family came to campus to watch. This month, they’ll return once more to cheer him on as he walks across the graduation stage. The milestone marks the end of a challenging but rewarding graduate school journey. 

“I'm incredibly proud of Sylvester,” Delilah said. “He's an amazing guy, as both a scientist and a human.”

Two Science Terps Are Born

What exactly does a kid do when they’re dragged into a university physics building? Actually, quite a lot, Sylvester and Delilah said. 

They have fond childhood memories of playing with physics demonstrations, mingling with employees and learning Japanese from a department staff member. Delilah even recalls playing physicist—much like many kids play doctor—scribbling gibberish on her dad’s blackboard and notepads as she pretended to do complex calculations. 

In many ways, the twins took after their parents. Their mother, Dianna Abney, is a pediatrician, child abuse specialist and the health officer for Charles County, Maryland. Like the kids, one of their parents studies physics, and the other is in the life sciences. Still, neither kid felt pressured by their parents to be scientists. In fact, both twins played the clarinet and considered majoring in music at UMD. 

“Though I have been deeply passionate about reaching my wish of becoming a scientist starting at age 4—as is similar to the case of my wife, Dianna, whose wish to become a medical doctor began around age 8—we shared a belief that parents should provide a safe environment with some structure, but stay out of the children's lanes of determining their lives' ambitions,” Jim said. 

That’s not to say Jim and Dianna did not influence their children’s careers at all. They were friends with other doctors, professors, lawyers and people with advanced degrees. Being around them helped the twins understand what went into pursuing those career paths, Delilah said. And, they were always invited to chat with the adults. 

“A lot of things that some people might think are hard discussions about science, the universe, planets, biology and medicine were commonplace, because that's just the language my mom and dad spoke,” Sylvester said. 

He added that representation was important. 

“It never felt like science was unapproachable to me,” Sylvester said. “This is one of the reasons why I believe that representation matters. Having a father and mother who were, respectively, a physicist and a pediatrician, both doctors in their own right, made being a doctor seem like something that my sister and I could do.”

Diverging Disciplines

Now that they’re both scientists, the twins study the world on vastly different scales—Sylvester works on microscopic cells, while Delilah researches the vast cosmos. The two siblings always had distinct dispositions, Sylvester said. He was always more artsy, and his sister was more drawn to math. So, he’s not surprised their interests diverged. 

Delilah initially planned to study particle physics like her father, but after taking a cosmology class in graduate school, she became fascinated by black holes. She was drawn to the discipline’s strong mathematical framework, which, like particle physics, builds on concepts like field theory and general relativity. Now, as a theoretical physicist, she’s developing new ways to measure the spin of black holes—a question that has vast implications for understanding how galaxies form and evolve.  

As for Sylvester, when he went to Duke University, he was planning to study cancer for his Ph.D. But living away from Maryland for the first time, he experienced culture shock—from the slower pace of life and the distance from the community he had spent two decades developing. For a year and a half, he struggled with his mental health and imposter syndrome. 

“Then, I was like, ‘I cannot do graduate school at this point in time,’” Sylvester said. “So I came back to Maryland. Thankfully, I had great support, so I was able to rebuild my scientific confidence.” 

Growing Together by Moving Apart

It was difficult for Delilah to watch her twin struggle, but ultimately, it brought them closer. Until that point in their lives, they had lived close enough to see each other and speak regularly. But they had to learn to be there for each other now that they lived hundreds of miles apart. 

“Him having struggled taught us how to support each other in a new way,” Delilah said. “It was difficult at first learning to be in different places and on different timelines, but it taught us a new way to communicate and connect.” 

The Gates family in 2015.The Gates family in 2015.When Delilah faced her own challenges about halfway through graduate school, that bond was invaluable.

“I always say I don't think I'll have a midlife crisis because I went through graduate school. I was struggling quite a lot. I was having severe anxiety. And it was to the point I would cry every day, sometimes several times a day,” she said. “I remember I used to call Sylvester most mornings and talk to him on the way to work, because talking to him made me less anxious.”

After supporting each other through tough times, the twins are closer than ever. They’re best friends and speak every day, whether that’s through text messages, phone calls or wordless exchanges of memes. After watching Sylvester bounce back from his struggles, Delilah was overjoyed as she watched her brother finally defend his Ph.D. It was her first time watching him deliver a scientific lecture, and she noted how calm, cool and collected he was—and also how well-dressed. 

“He's so much more fashionable than me,” she said with a laugh. “He looked really sharp.”

Delilah got emotional as she recounted the day’s events. 

“I was the last one he shouted out in detail in his acknowledgments, and I just bawled. I couldn't contain my joy and pride. I was so happy for him,” she said. “Even thinking about it now, I get a little verklempt.” 

Their father felt the same way. 

“It would take me writing a magnum opus to really express my feelings in the defense,” Jim said.

Now that he’s completed his Ph.D., Sylvester is still figuring out what’s next. He’s open to academia, or maybe a career in government or industry. Wherever he lands, he wants to continue studying how the brain works, whether that means developing artificial neural networks for computing, medicines for neurodegenerative diseases like Alzheimer’s or interventions to help military veterans dealing with brain trauma. 

And although the twins’ physics professor dad never pushed either child to pursue science, he’s thrilled by their accomplishments now that they have chosen the path for themselves. 

“Raising them was amazing. My wife and I still say that there is nothing else in life that we have done that was more fun,” Jim said. 

It’s hard for him to find the words to describe how he feels witnessing his children’s success. So, he turns to something of a family heirloom—cherished words his father once shared with him. 

“After I became the John S. Toll Professor of Physics, my father said to me, ‘You have exceeded any and all expectations that your mother, Charlie, and I ever had of and for you,” Jim said. “My twins have accomplished that also for their parents.”

Barkeshli Selected for Frontiers of Science Award

Research by Professor Maissam Barkeshli and colleagues has been selected by the International Congress of Basic Science (ICBS) as a recipient of the 2026 Frontiers of Science Award in Condensed Matter Physics. The paper cited was Symmetry fractionalization, defects, and gauging of topological phases by Barkeshli, Parsa Bonderson, Meng Cheng and Zhenghan Wang.Maissam BarkeshliMaissam Barkeshli

The Frontiers of Science Award, inaugurated in 2023 under the auspices of the ICBS, honors recent papers recognized for a major breakthrough in their respective fields and includes a nomination process and review by a panel of experts.

Awards will be presented at the International Congress of Basic Science in Beijing on August 9, 2026. 

Barkeshli has also received a Sloan Fellowship and an NSF Career Award, and was recently selected for a Simons Collaboration

Kara Hoffman Named Chair of Department of Physics

Professor Kara Hoffman was named chair of the Department of Physics, effective July 1, 2026.Kara Hoffman. Photo courtesy of same.Kara Hoffman. Photo courtesy of same.

“Kara Hoffman brings to this role a record of scholarly achievement and an understanding of the department's strengths and aspirations,” said Amitabh Varshney, dean of UMD’s College of Computer, Mathematical, and Natural Sciences. “As a longstanding member of our faculty, she is prepared to lead the department’s continued growth and success.”

The Department of Physics ranks No. 14 overall (and 5th among public institutions) in physics graduate programs according to U.S. News & World Report and has 50 tenured/tenure-track faculty members, nearly 600 students and annual research funding of over $30 million. 

“It is an honor to be chosen to chair a department of this prominence," Hoffman said. “The strength of the department derives from the talent of our faculty and students, the dedicated support of our staff, as well as our partnerships with some of the world’s preeminent research institutions.” 

Hoffman plans to continue recruiting outstanding faculty members and students and providing excellent opportunities outside the classroom for the large fraction of physics majors who conduct research.

“As chair, I look forward to supporting these activities, as well as looking for new opportunities and initiatives,” Hoffman added. “While these are challenging times for research funding, I believe we can emerge even stronger.”Kara Hoffman at the South Pole. Photo courtesy of same.Kara Hoffman at the South Pole. Photo courtesy of same.

Hoffman, who joined UMD in 2004, serves as the principal investigator on the National Science Foundation (NSF) grant that supports the analysis of data taken with the world’s largest neutrino telescope, the IceCube Neutrino Observatory at the South Pole. She has been conducting research at the observatory since the construction of the telescope commenced in 2004. 

Scientists have used IceCube to discover a population of high-energy neutrinos originating from outside our galaxy and from within the Milky Way plane. In addition, IceCube has made several contributions to particle physics, including the first observation of the Glashow resonance. 

Hoffman’s research has focused on multimessenger astrophysics, which aims to correlate information across multiple telescopes—including optical, gamma-ray and gravitational-wave instruments—often in real time, to identify some of the most energetic objects in our universe and gain a deeper understanding of the physical processes that drive them. 

In addition, Hoffman received an NSF Major Research Instrumentation grant that funded the construction of a next-generation neutrino array, the Askaryan Radio Array, also at the South Pole. The array is one of a few instruments pioneering a new detection technique that would extend the sensitivity of neutrino telescopes to higher energies.

Hoffman has held various leadership roles at UMD, including as director of the Center for Experimental Fundamental Physics (2012-15), as a faculty senator (2015-18) and as the department’s associate chair for undergraduate education (2016-20). In the latter role, she restructured the undergraduate laboratory sequence, facilitated the inclusion of active learning in undergraduate courses, recruited new instructors and oversaw the transition to online learning during the pandemic.  Hoffman is also a Fellow of the Joint Space-Science Institute and has served in various leadership roles within her field, including as a member of the executive committee of the Division of Particles and Fields at the American Physical Society (2010-13).Kara Hoffman at the South Pole. Photo courtesy of same.Kara Hoffman at the South Pole. Photo courtesy of same.

She has mentored more than a dozen postdoctoral researchers and graduate students. Hoffman earned her Ph.D. in high-energy physics in 1998 and her master’s degree in physics in 1994 from Purdue University and her bachelor’s degree in physics from the University of Kentucky in 1992. Before joining UMD, she was a Fellow at CERN and a research associate at the University of Chicago’s Enrico Fermi Institute. 

Hoffman succeeds Steve Rolston, who completed a 10-year term as physics chair. During Rolston’s tenure as chair, he hired 14 faculty members, founded the Mid-Atlantic Quantum Alliance, sponsored the Conference for Undergraduate Women in Physics, and sponsored four Conferences for Undergraduate Underrepresented Minorities in Physics—while also successfully navigating the department’s operations during the pandemic. During the past decade, six physics faculty members were elected to the National Academy of Sciences, four were named Distinguished University Professors and four were named Distinguished Scholar-Teachers. While chair, Rolston also maintained his own quantum research program, authoring 32 publications and graduating eight Ph.D. students.