New physics in B decays? Challenges to Lepton Flavor Universality from LHCb and the B factories  

Since the establishment of the Standard Model (SM) many decades ago, the three types of charged leptons (electron, muon, and tau) have been seen as doppelgängers of each other in everything but their readings on the scale. That is, the SM interactions of the three lepton families with other particles differ only because of their different masses. This resulting (accidental) symmetry is known as Lepton Flavor Universality (LFU). Since 2012, however, a series of measurements of decays involving tree-level b → cτν and loop-level b → sℓℓ transitions (the so-called "B anomalies") have repeatedly hinted at the possibility that lepton universality may be, in fact, violated. This pattern was reinforced in March 2021 when LHCb reported the first deviation from the SM by more than 3σ in a single LFU observable, one which is affected by negligible theoretical uncertainties. In this talk I will go over the current status of LFU measurements as well as their compatibility with exotic leptoquarks, and will briefly review the prospects for the upcoming LHCb and Belle II datasets to resolve the anomalies one way or another.

Towards Topological Superconductivity in Epitaxial Superconductor-Semiconductor Materials Systems  

A central goal in condensed matter physics is to understand and control the order parameter characterizing the collective state of electrons in quantum heterostructures. For example, new physical behaviors can emerge that are absent in the isolated constituent materials. With regards to superconductivity this has opened a whole new area of investigation in the form of topological superconductivity. This type of superconductivity is expected to host exotic quasi-particle excitations including Majorana bound states which hold promise for fault-tolerant quantum computing. In this talk,
we first discuss the important role of epitaxial superconductor-semiconductor hybrid systems as an enabling materials platform. We present unprecedented values of transparency and induced gap that could allow us to reach into previously unexplored parameter regimes. In wide Josephson junctions exposed to magnetic field, we observe a minimum of critical current accompanied with a phase jump in the superconducting phase. We discuss this observation as a signature of a transition between trivial and topological superconductivity. These findings in addition to new directions in proximitizing edge modes reveal a versatile two-dimensional platform to explore mesoscopic and topological superconductivity.

Climate Change and Extreme Summer Weather Events  

In addition to well-established direct physical linkages between a warming planet and extreme summer weather events such as floods, droughts, heat waves and wildfires are more tenuous but potentially profound linkages tied to altered characteristics of the Northern Hemisphere jet stream and associated wave disturbances. Some of the most significant extreme summer weather events in recent years have been associated with high-amplitude quasi-stationary Rossby waves with zonal wavenumbers 6-8 tied to the phenomenon of Quasi-Resonant Amplification (QRA). Current state-of-the-art (CMIP5) climate models are unable to adequately resolve this mechanism owing to substantial errors in the models in the curvature of the zonal velocity field which is a key quantity controlling the associated wave disturbances. A reliable fingerprint for the occurrence of QRA can, however, be defined in terms of the zonally-averaged surface temperature field. Examining climate observations and historical (CMIP5) climate model simulations, we have demonstrated consistent evidence for an increasing trend in QRA events over the past half century tied to anthropogenic warming. Examining CMIP5 model projections we find that QRA-related extreme weather events are likely to increase by ~50% this century under business-as-usual carbon emissions, but there is considerable variation among climate models, and a reduction in mid-latitude aerosol loading could actually lead to Arctic de-amplification this century, ameliorating potential further increases in persistent extreme weather events. Given the uncertainties, substantial further increases in these events cannot however be ruled out.

Bio: Dr. Michael E. Mann is Distinguished Professor of Atmospheric Science at Penn State, with joint appointments in the Department of Geosciences and the Earth and Environmental Systems Institute (EESI). He is also director of the Penn State Earth System Science Center (ESSC). Dr. Mann was a Lead Author on the Observed Climate Variability and Change chapter of the Intergovernmental Panel on Climate Change (IPCC) Third Scientific Assessment Report in 2001 and was organizing committee chair for the National Academy of Sciences Frontiers of Science in 2003. He has received a number of honors and awards including NOAA's outstanding publication award in 2002 and selection by Scientific American as one of the fifty leading visionaries in science and technology in 2002. He contributed, with other IPCC authors, to the award of the 2007 Nobel Peace Prize. Dr. Mann is author of more than 200 peer-reviewed and edited publications, numerous op-eds and commentaries, and five books. 

Perspective on John S. Toll’s “OmniPolymathism” From an Age of Skepticism

I first met John S. Toll during the late nineteen eighties during the time he was leading the University Research Associates (URA) while it sought to build the Superconducting Super Collider. Had it been built, the ‘Higgs Boson,’ an elementary particle, would have been discovered in the USA, not at the Large Hadron Colliderin Europe. One night in the physics department, I saw an elderly gentleman and wondered whether he was lost. Little did I know then, this man was the creator of the modern University of Maryland. I learned this and many more things later.

This talk is a presentation about some of these lessons.

Quantum Technologies for New-physics Discoveries

The extraordinary advances in quantum control of matter and light have been transformative for atomic and molecular precision measurements enabling probes of the most basic laws of Nature to gain a fundamental understanding of the physical Universe. Exceptional versatility, inventiveness, and rapid development of precision experiments supported by continuous technological advances and improved atomic and molecular theory led to rapid development of many avenues to explore new physics. I will give a broad overview of atomic and molecular physics searches for physics beyond the standard model. Several examples will be highlighted, including searches for permanent electron electric-dipole moment that probe new TeV-scale physics, dark matter searches with atomic and nuclear clocks, and new ideas in gravitational wave detection with atomic quantum sensors. 

Order, disorder and the entropic bond: The Truth About Entropy

Entropy is typically associated with disorder; yet, the counterintuitive notion that particles with no interactions other than excluded volume might self-assemble from a fluid phase into an ordered crystal has been known since the mid-20th century. First predicted for rods, and then spheres, the thermodynamic ordering of hard particle shapes by nothing more than crowding is now well established. In recent years, surprising discoveries of entropically ordered colloidal crystals of extraordinary structural complexity have been predicted by computer simulation and observed in the laboratory. Colloidal quasicrystals, clathrate structures, and structures with large and complex unit cells typically associated with metal alloys can all self-assemble from disordered phases of identical nanoparticles due solely to entropy maximization. In this talk, we show how entropy alone can produce order and complexity beyond that previously imagined.  We introduce the notion of the entropic bond, and show how methods used by the quantum community to predict atomic crystal structures can be used to predict entropic colloidal crystals.

Structural Color - Origin and Evolution in Nature  

Structural color originates from physical interaction of light with nanostructures. Most studies so far have focused on ordered structures which produce iridescent colors that change with viewing angle. However, nature has used extensively quasi-ordered structures to create weakly iridescent colors. An interdisciplinary team, consisting of optical physicists, material scientists, and biologists at Yale, has investigated the physical mechanism for coloration of nanostructures with short-range order in bird feather barbs. Inspired by nature, a simple technique is developed to fabricate large-scale biomimetic films which display isotropic structural color, that is amenable to potential applications in coatings, cosmetics, and textiles. In order to understand how the structural color evolves in nature, artificial selection has been conducted on a lab model butterfly to evolve the structural color of wing scales and compared to natural selection. This study reveals the physical mechanism of structural color evolution, which stands in sharp contrast to pigment color evolution.

The Emergence of Topological Quantum Matter

Matter can arrange itself in the most ingenious ways.   In addition to the solid, liquid and gas phases that are familiar in classical physics, electronic phases of matter with both useful and exotic properties are made possible by quantum mechanics.  In the last century, the thorough understanding of the simplest quantum electronic phase - the electrical insulator - enabled the development of the semiconductor technology that is ubiquitous in today's information age.   In the present century, new "topological" electronic phases are being discovered that allow the seemingly impossible to occur:  indivisible objects, like an electron or a quantum bit of information, can be split into two, allowing mysterious features of quantum mechanics to be harnessed for future technologies.  Our understanding of topological phases builds on deep ideas in mathematics.   We will try to convey that they are as beautiful as they are fundamental.

TBA

The Public Relations Machine in Science: A Self-Inflicted Wound?

James Glanz grew up in radio and television stations as the son of a sportscaster and DJ in the Midwest. Dead broke in college, he talked his way into a job at a physics lab, eventually earning a Ph.D. in Astrophysical Sciences at Princeton. He then turned to journalism, and at Science magazine broke stories like the discovery of dark energy in the universe. At the New York Times, he covered the collapse of the twin towers on Sept. 11 and spent two years reporting from ground zero. In 2003, with Eric Lipton, he published City in the Sky: The Rise and Fall of the World Trade Center. He has also been the Times’s Baghdad bureau chief and has covered disasters ranging from the fire at the Notre Dame cathedral to the crashes of two Boeing 737 Max jetliners.

 

  

The Simple (and Not-So-Simple) Physics of Detecting Gravitational Waves