Manuel Franco Sevilla Receives Junior Faculty Award

Manuel Franco Sevilla installs ODMB modules into the CMS detector at CERN. (Photo: Jeff Richman)

Manuel Franco Sevilla has received the 2022 Junior Faculty Award from the Board of Visitors of the College of Computer, Mathematics and Natural Sciences in recognition of his “exceptional accomplishments that have raised the profile and prestige of the college”.

Franco Sevilla is a particle physicist doing research at CERN’s Large Hadron Collider’s beauty (LHCb) experiment, which employs “beauty” (or “b”) hadrons produced in high-energy collisions of protons to study the fundamental laws of our Universe.Manuel Franco Sevilla Manuel Franco Sevilla

His research focuses on measurements that test lepton universality, a fundamental assumption within the Standard Model of particle physics that states that the interactions of all charged leptons (electrons, muons, and taus) differ only because of their different masses. His thesis in 2012 saw the first hints of possible lepton universality violation, and since then, several measurements in experiments across the world have found similar hints. He has covered this topic in multiple international forums and in reviews for Nature and Review of Modern Physics.

Additionally, Franco Sevilla works on the Upstream Tracker (UT), a new silicon tracker that is a crucial part of LHCb’s ongoing upgrade to achieve data taking rates five times larger than previously possible. Together with Professor Hassan Jawahery, he co-led the development and production of the readout electronics for the UT, a total of over 600 main boards and 3,000 ancillary ones. This immense effort included contributions from an electronics engineer, three postdocs, four graduate students and the recruitment and training of a group of 12 undergraduate students who were instrumental during the testing and assembly phases of the project.

Last year Franco Sevilla was named deputy project leader of the UT and spent the second half of 2022 at CERN coordinating the assembly and installation of this subdetector into the LHCb experiment, an effort that involved a team of over 25 engineers, technicians, postdocs, and students as well as other CERN resources such as survey, transportation, or radiation protection teams. Some pictures of theses activities are shown below.

(Possibly) Breaking the Standard Model, One Lepton-universality-violating Decay at a Time

Physicists in general, and high energy physicists in particular, like to "break" things. It can be useful to prove again that a well established theory is true, especially if you are probing a yet-untested prediction of the venerable theory. But proving that the theory is wrong--or at least not completely true--that is where the fun is. This is why a series of measurements of b hadron decays that seemingly break the Standard Model (SM) of particle physics is garnering so much excitement.

You see, the SM is the most well established theory of them all, the only one with predictions corroborated to the 11th digit (see the anomalous magnetic moment of the electron). It was fully fleshed out in the 70's, and since then it has racked up success after success. Its crowning achievement came in 2012 when the long-predicted Higgs boson was finally confirmed to be alive and well. Despite this resiliency, the SM is not the end of it all. It can't explain why the mass of the Higgs is so low, what the nature of dark matter is, or why there is so much more matter than antimatter in the universe. Finding answers to these questions will thus require breaking, or extending, the SM.

Enter Lepton Flavor Universality (LFU) violation. LFU is a fundamental assumption within the SM involving the three lepton flavors: electron, muon, and tau. All SM interactions other than the Higgs are assumed to be flavor universal, and this has been shown to be true in numerous measurements. Since 2012, however, an intriguing pattern has emerged in decays of b hadrons (particles with a b quark inside) to final states with a c quark, a tau lepton τ, and a neutrino ν. When results involving a tau lepton and a neutrino are compared to decays involving a muon or an electron and a neutrino, they tend to be higher than we'd expect from SM calculations. This is shown in the nearby figure by all the measurements keeping their distance from the theoretical predictions in blue. Measurements that measured the two LFU quantities RD and RD* are shown as Artistic representation of a proton-proton collision resulting in a B meson that subsequently decays to a charmed D0 or D* meson, a tau lepton, as well as a smaller antineutrino. Credit: Greg Stewart, SLAC National Accelerator Laboratory/BaBar and Manuel Franco Sevilla.Artistic representation of a proton-proton collision resulting in a B meson that subsequently decays to a charmed D0 or D* meson, a tau lepton, as well as a smaller antineutrino. Credit: Greg Stewart, SLAC National Accelerator Laboratory/BaBar and Manuel Franco Sevilla.ellipses while measurements of RD* alone are shown as markers with uncertainties.
None of these results on their own rises to what is typically known as an "observation" (5σ statistical significance), and it could very well go away. For instance, a similar pattern that had appeared when comparing decays involving a kaon and two muons to decays with a pair of electrons was recently shown to be an artifact  of an underestimated background. But the consistency among results that share the same b→ cτν underlying process is very suggestive. Multiple explanations have been proposed that would explain all of these with physics beyond the SM (BSM). A particularly neat solution postulates a new kind of exotic particle that interacts with both leptons and quarks: a vector leptoquark. 
In an article published last year in Review of Modern Physics ("Semitauonic b-hadron decays: A lepton flavor universality laboratory"), my co-authors and I comprehensively described these results, delved into the main sources of uncertainty, and mapped out the future measurements. Spoiler alert: while we do not know whether BSM physics will be discovered, we are rather confident that we will know whether these results are due to BSM physics or not within 5-10 years. 
And the first of these new results was just submitted to Physical Review Letters  Professor Hassan Jawahery and Dr. Phoebe Hamilton, together with Dr. Greg Ciezarek from CERN, measured for the first time RD and RD* simultaneously at LHCb. The uncertainties are still large, so it is hard to say whether the discrepancy will be proven true. But this result sets the stage for another meaThe results reflect analysis of two years of data by Phoebe Hamilton and Hassan Jawahery and their CERN collaborator, Greg Ciezarek.The results reflect analysis of two years of data by Phoebe Hamilton and Hassan Jawahery and their CERN collaborator, Greg Ciezarek.surement based on the same techniques that uses a data sample more than 6 times larger. This work, carried out by the all-UMD team Professor Manuel Franco Sevilla, Dr. Hamilton, Dr. Christos Hadjivasiliou, Yipeng Sun, and Alex Fernez, is now fairly advanced. So stay tuned, there's potential for SM-breaking ahead!

 --Manuel Franco Sevilla



James J. Griffin, 1930-2022

Professor Emeritus James J. Griffin died on December 13, 2022.

Griffin earned his Ph.D. in theoretical physics at Princeton University in 1956 and then accepted a Fulbright Scholarship to the Institute for Theoretical Physics in Copenhagen. Following a National Science Foundation Fellowship at the University of Birmingham and an appointment as a Visiting Lecturer at the University of Wisconsin, he joined UMD as an assistant professor in 1966. He was promoted to associate professor and full professor in 1968 and 1973, respectively. In the 1968-69 academic year, Griffin served as Associate Chair of the UMD Department of Physics and Astronomy.

Griffin studied nuclear structure and heavy ions, and was perhaps best known for his publication, “The statistical model of intermediate structure,” which appeared in Physical Review Letters.  He received a John Simon Guggenheim Foundation Fellowship to work at the Lawrence Berkeley Laboratory in 1972-73. In 1975, he received an Alexander von Humboldt Foundation Senior Scientist Fellowship and worked at the Justus Liebig University in Giessen and the Hahn Meitner Institute for Nuclear Research in Berlin.   

During his career, Griffin also enjoyed visiting positions at Los Alamos National Laboratory, Oak Ridge National Laboratory, the University of California in Berkeley, and several institutions in France and Germany. He was an invited guest lecturer in Germany, Canada, Poland, China, Israel, Japan, France and Romania. 

A memorial is planned for the spring. If you'd like to be notified when it is scheduled, please contact This email address is being protected from spambots. You need JavaScript enabled to view it..

Wolfgang Losert Elected AAAS Fellow

Wolfgang Losert  has been elected a Fellow of the American Association for the Advancement of Science. Wolfgang Losert. Credit: UMD/Lisa Helfert. Wolfgang Losert. Credit: UMD/Lisa Helfert.

In his research, Losert aims to discover emergent dynamic properties of complex systems at the interface of physics and biology. He currently leads a Multidisciplinary University Research Initiative program funded by the Air Force Office of Scientific Research that transformed our understanding of how cells sense their physical environment. He also serves as co-principal investigator on a Brain Research through Advancing Innovative Neurotechnologies (BRAIN) initiative center grant from the National Institutes of Health focused on information processing in sensory brain circuits.

Losert actively fosters cross-disciplinary interactions and new research and educational opportunities on campus and beyond. He helped launch and currently co-leads the American Physical Society Group on Data Science. He was part of a trans-university initiative of the Howard Hughes Medical Institute (called NEXUS) that developed new science and math courses for biology majors and pre-health care students that are being widely adopted. He led the development of and co-directs the NCI-UMD Partnership for Integrative Cancer Research, which provides UMD faculty members and graduate students the opportunity to tackle pressing problems in cancer research in collaboration with National Cancer Institute experts. 

A Fellow of the American Physical Society, Losert joined UMD in 2000 as an assistant professor and served as an associate dean in CMNS (2014-22) and as interim IPST director (2019-20). He earned his Ph.D. in physics from the City College of the City University of New York in 1998 and his diplom in applied physics from the Technical University of Munich in Germany in 1995.

Also elected from the College of Computer, Mathematical, and Natural Sciences (CMNS) were  mathematician Abba Gumel and computer scientists Mohammad Hajiaghayi  and Dana Nau.

“I join the CMNS community in congratulating Professors Gumel, Hajiaghayi, Losert and Nau on their well-deserved election as AAAS Fellows,” said CMNS Dean Amitabh Varshney. “This is an affirmation of what we already know—that they are each pushing the boundaries in their respective fields and making a significant impact on the grand challenges our society faces today.”

UMD’s 2022 Fellows, seven in total, join a class of 506 new Fellows who have moved their fields forward, paving the way for scientific advances that benefit society. They bring diverse and novelty thinking, innovative approaches and passion that will help solve the world’s most complex problems, according to AAAS’s announcement.

“AAAS is proud to elevate these standout individuals and recognize the many ways in which they’ve advanced scientific excellence, tackled complex societal challenges and pushed boundaries that will reap benefits for years to come,” Sudip S. Parikh, AAAS chief executive officer and executive publisher of the Science family of journals, said in an announcement.