Particle physics research

Campus Point: New and Exciting Research at UCSB

Luca Disbrow / Daily Nexus

Cracks in quark theory

Theoretical physicists Abraham Pais and Sam Treiman proposed the Standard Model in 1975, which explains three of the four forces that govern matter in our universe. The forces explained are the electromagnetic force, the strong force and the weak force. Simply put, these forces all play a role in what holds matter matters – such as quarks, protons and neutrons – together. The fourth force, which is gravitational force, is not explained by the Standard Model (SM). It is into this specific gap, as well as the inability to describe dark matter in a manner consistent with the model, that Claudio Campagnari, professor and department chair in the physics department at UC Santa Barbara, comes into play. perspective article published in Science MagazineCampagnari presents potential measures that contradict the SM, in particular from the O boson – one of the building blocks associated with the weak force responsible for radioactive beta decay. Campagnari postulates that an accurate measurement of the mass of a O boson could invalidate the coherence of the SM. Campagnari is part of the Collider Detector at Fermilab (CDF) collaboration as part of its association with the European Organization for Nuclear Research. Those in the CDF collaboration, including Campagnari, were able to produce extremely accurate measurements of the O boson that directly contradict the SM, such as the O boson was measured to be heavier than the SM predicts by seven standard deviations. As more and more measurements are made, not only of the O boson but other components that make up matter, Campagnari believes that through the work of the CDF collaboration, more cracks in SM theory can be found, potentially leading to a better theoretical understanding of how the forces of the universe control the formation of matter.

Sticky science

Virgile Thiévenaz, postdoctoral researcher at UCSB, and Alban Sauret, assistant professor in the department of mechanical engineering, recently published a paper in the journal Proceedings of the National Academy of Sciences discuss the viscosity of fluids and how the suspension of particles in various liquids can induce various properties and behaviors of liquids. Viscosity is a measure of how difficult it is to change the physical conformation of a liquid. Honey is an example of a viscous fluid, in that it is less “willing” to move than, say, water. Researchers have already understood that the presence of particles in a liquid increases its viscosity, but the mystery lies in why and how studying the suspension of particles becomes more difficult on larger scales. Thievenaz and Sauret sought to explain it. They found that particles do not spread uniformly at very small scales, ultimately leaving areas in a given amount of fluid that contain no particles and therefore act like pure fluid. Through experimentation with droplets, Thiévenaz and Sauret observed that there is a thickness threshold for fluids which, when crossed, makes the particles impossible to separate, leading to an effective viscosity equal to that of a pure liquid. The researchers also concluded that this threshold depends on the size and concentration of the particles. These observations are an important advance in the study of fluids and provide crucial context for industry professionals dealing with fluids in manufacturing processes, such as coating products with varnish or paint. The results also provide a promising basis for further research into fluid composition and behavior, including the study of similar suspension systems, such as thin films, as well as liquids containing non-spherical particles, such as fibers.

Climatic disasters

In recent years, there has been an increase in instances of wildfires followed by extreme rainfall across the western United States. The impacts of this continuing pattern are expected to have dire consequences, including an increased risk of debris flows, loss of vegetation and flash flooding. UCSB Bren School of Environmental Science & Management researchers Danielle Touma and Samantha Stevenson reported the increased frequency of post-wildfire extreme precipitation events that occurred less than a year apart . With their findingspaired with the Community Earth System Model v1 Big Set, joint disasters are projected to likely increase by 100% in California and 700% in the 2,100 Pacific Northwest. Additionally, the results suggest that increased post-fire hydraulic hazards would affect most of the western United States. At least three extreme precipitation events are expected to follow 90% of wildfires in California, Colorado and the Pacific Northwest over the next five years.

A version of this article appeared on p. 15 of the April 14 print edition of the Daily Nexus.