LHC Scientists Finally Detect Most Favored Higgs Decay

ZeeEvent Aug21 v5Candidate event showing the associated production of a Higgs boson and a Z boson, with the subsequent decay of the Higgs boson to a bottom quark and its antiparticle.

Scientists now know the fate of the vast majority of all Higgs bosons produced in the LHC.

Today at CERN, the Large Hadron Collider experiments ATLAS and CMS jointly announced the discovery of the Higgs boson transforming into bottom quarks as it decays. This is predicted to be the most common way for Higgs bosons to decay, yet was a difficult signal to isolate because it closely mimics ordinary background processes. This new discovery is a big step forward in the quest to understand how the Higgs enables fundamental particles to acquire mass.

After several years of refining their techniques and gradually incorporating more data, both experiments finally saw evidence of the Higgs decaying to bottom quarks that exceeds the 5-sigma threshold of statistical significance typically required to claim a discovery. Both teams found their results were consistent with predictions based on the Standard Model. UMD professors Alberto Belloni, Drew Baden, Sarah Eno, Nick Hadley and Andris Skuja are members of the CMS collaboration.

Higgs bosons are only produced in roughly one out of a billion LHC collisions and live only one-septillionth of a second before their energy is converted into a cascade of other particles. Because it is impossible to see Higgs bosons directly, scientists use these secondary particles to study the Higgs’ properties. Since its discovery in 2012, scientists have been able to identify only about thirty percent of all the predicted Higgs boson decays, while its decays to bottom quarks, which should occur sixty percent of the time, had not yet been observed.

“The Higgs boson is an integral component of our universe and theorized to give all fundamental particles their mass,” said Alberto Belloni of the University of Maryland. “But previously we had only directly seen the Higgs couplings to the tau lepton, and the W and Z bosons. Now we have seen the decay of the Higgs to a quark-antiquark pair. This measurement shows for the first time that the Higgs gives mass to a quark.”

The Higgs field is theorized to interact with all massive particles in the Standard Model, the best theory scientists have to explain the behavior of subatomic particles. But many scientists suspect that the Higgs could also interact with massive particles outside the Standard Model, such as dark matter. By finding and mapping the Higgs bosons’ interactions with known particles, scientists can simultaneously probe for new phenomena.

The next step is to increase the precision of these measurements so that scientists can study this decay mode with a much greater resolution and explore what secrets the Higgs boson might be hiding.

Further information:

ATLAS: https://atlas.cern/updates/press-statement/observation-higgs-boson-decay-pair-bottom-quarks

CMS: http://cms.cern/higgs-observed-decaying-b-quarks-submitted

JQI Scientists Monroe and Gorshkov are Part of a New, $15 Million NSF Quantum Computing Project

ion trapA fabricated trap that researchers use to capture and control atomic ion qubits (quantum bits). (Credit: K. Hudek/IonQ and E. Edwards/JQI)NSF has announced a $15 million award to a collaboration of seven institutions including the University of Maryland. The goal: Build the world’s first practical quantum computer.

"Quantum computers will change everything about the technology we use and how we use it, and we are still taking the initial steps toward realizing this goal," said NSF Director France Córdova. "Developing the first practical quantum computer would be a major milestone. By bringing together experts who have outlined a path to a practical quantum computer and supporting its development, NSF is working to take the quantum revolution from theory to reality."

Dubbed the Software-Tailored Architecture for Quantum co-design (STAQ) project, the new effort seeks to demonstrate a quantum advantage over traditional computers within five years using ion trap technology.

The project is the result of a National Science Foundation Ideas Lab—a week-long, free-form exchange among researchers from a wide range of fields that aims to spawn creative, collaborative proposals to address a given research challenge. The result of each Ideas Lab is interdisciplinary research that is high-risk, high-reward, cutting-edge and unlikely to be funded through traditional grant mechanisms.

JQI Fellow Christopher Monroe will lead the team developing the hardware. JQI Fellow Alexey Gorshkov will be involved in the theory side of the collaboration.

Text for this news item was adapted from the Duke University and NSF press releases on the award.

RESEARCH CONTACT
Christopher Monroe | This email address is being protected from spambots. You need JavaScript enabled to view it.;
MEDIA CONTACT
Emily Edwards | This email address is being protected from spambots. You need JavaScript enabled to view it.

Davoudi Receives Ken Wilson Award

Assistant Professor Zohreh Davoudi has been honored with the 2018 Kenneth G. Wilson Award for Excellence in Lattice Field Theory during the 36th Annual International Symposium on Lattice Field Theory held July 22–28 at Michigan State University. Davoudi was cited for her fundamental contributions to lattice field theory in a finite volume that are essential for performing lattice simulations of complex systems.

The annual award is named after Nobel Laureate Ken Wilson (1936-2013), who founded lattice gauge theory in 1974, permitting such theories to be studied numerically using powerful computers. Established in 2011, the award recognizes outstanding lattice field theorists who are within seven years of completing the Ph.D., and consists of a modest monetary prize and an invitation to give a plenary talk at the next symposium on lattice field theory.

Davoudi’s significant contributions to formulating the path between quantities obtained in numerical simulations of lattice field theory in a finite spacetime and the physical observables have advanced the few-body frontier in lattice field theory. The cited work paved the road towards obtaining important quantities in particle and nuclear physics, such as two and three-body scattering amplitudes, bound-state properties, electromagnetic structure of hadrons and nuclei, coupled-channel scattering and reaction rates.

Davoudi received her Ph.D. in theoretical nuclear physics at the University of Washington, and held a postdoctoral position at the Center for Theoretical Physics at the Massachusetts Institute of Technology before joining UMD in 2017. She studies how complex systems of hadrons and nuclei emerge from fundamental interactions of nature using a combination of analytical and computational methods.

zohreh receiving Ken Wilson Lattice AwardPhoto courtesy of Lattice 2018. Christine Davies, University of Glasgow (left) Zohreh Davoudi, University of Maryland (right).

Complexity Test Offers New Perspective on Small Quantum Computers

State-of-the-art quantum devices are not yet large enough to be called full-scale computers. The biggest comprise just a few dozen qubits—a meager count compared to the billions of bits in an ordinary computer’s memory. But steady progress means that these machines now routinely string together 10 or 20 qubits and may soon hold sway over 100 or more.

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