BNL Physics Department Videos

Physics Colloquium of 26 March 2024
"The Higgs boson and the fate of our universe"
Viviana Cavaliere, BNL

As the most recently discovered and thus least studied fundamental particle, the Higgs boson offers enormous opportunity for continuing to understand the fundamental forces and particles that make up our Universe. With the Higgs boson mass of 125 GeV the vacuum sits very close to the border of stable and metastable, which may be a hint to deeper physics beyond the Standard Model. The Higgs potential also plays an important role in ideas about the cosmological constant or dark energy that drives the accelerating expansion of the Universe, the mysterious dark matter that comprises about 80% of the matter component in the Universe, as well as a possible phase transition in the early Universe that might be responsible for baryogenesis. Present measurements at the Large Hadron Collider are focused on testing the Higgs boson's couplings to other elementary particles, precision measurements of the Higgs boson's properties and initial investigation of the Higgs boson's self-interaction and shape of the Higgs potential. I will discuss two new measurements that will help shed light on some of these questions and can direct future searches and finish with a brief look on what's to come.

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Physics Colloquium of 21 March 2024
"Ab initio nuclear structure theory and implications for relativistic heavy-ion collisions"
Dean Lee, Michigan State University

This talk starts with a review of ab initio nuclear structure theory, covering the various different methods currently being used. It then considers measurements of nuclear structure in low-energy experiments and the complementary information one might deduce from relativistic heavy-ion collisions. The talk then focuses on nuclear lattice simulations and the calculation of A-nucleon probability distributions. The cluster structure of several light nuclei are presented and predictions are discussed for 16O-16O and 20Ne-20Ne collisions.

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Physics Colloquium of 12 March 2024
"Recent results from the IceCube Neutrino Observatory and the prospects for IceCube-Gen2"
Erik K. Blaufuss, Univ.of Maryland

The IceCube Neutrino Observatory instruments a cubic-kilometer of glacial ice under the Amundsen-Scott South Pole Station, Antarctica to detect neutrinos above ~100 GeV and perform astroparticle observations of the Universe. Astrophysical neutrinos are expected to be created in the birthplaces of high-energy cosmic rays, and point the way back to these elusive sources. Since IceCube's detection of a diffuse flux of high-energy astrophysical neutrinos in 2013, identifying their sources has been the primary science goal. This talk with will present the latest measurements of the astrophysical neutrino flux, highlight results from realtime alerts generated by astrophysical neutrino detections that trigger rapid follow-up observations by the community and the recent observation of neutrinos from our Milky Way galaxy. Future upgrades to IceCube will also be discussed, including the physics potential of a future IceCube-Gen2 facility at the South Pole.

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Physics Colloquium of 5 March 2024
"The DNA of Particle Scattering"
Lance Dixon, SLAC

Scattering amplitudes are where quantum field theory meets particle experiment, especially at the Large Hadron Collider where the copious scattering of quarks and gluons in quantum chromodynamics (QCD) produces Higgs bosons and many backgrounds to searches for new physics. Particle scattering in QCD and other gauge theories is far simpler than standard perturbative approaches would suggest. Modern approaches based on unitarity and bootstrapping dramatically simplify many computations previously done with Feynman diagrams. Even so, the final results are often highly intricate, multivariate mathematical functions, which are difficult to describe, let alone compute. In many cases, the functions have a "genetic code" underlying them, called the symbol, which reveals much of their structure. The symbol is a linear combination of words, sequences of letters analogous to sequences of DNA base pairs. Understanding the alphabet, and then reading the code, exposes the physics and mathematics underlying the scattering process, including new symmetries. For example, the two scattering amplitudes that are known to the highest orders in perturbation theory (8 loops) are related to each other by a mysterious antipodal duality, which involves reading the code backwards as well as forwards. A third scattering amplitude, which contains both of these as limits, has an antipodal self-duality which "explains" the other duality. However, we still don't know `who ordered' this property, or what it really means.

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Physics Colloquium of 27 February 2024
"Random Coupling Models"
Vladimir Rosenhaus, CUNY Graduate Center

There is a long history, in both classical and quantum physics, of models with couplings that are random variables. An example is the Sachdev-Ye-Kitaev model which, over the past decade, has emerged as the harmonic oscillator of chaotic many-body systems. We discuss the model and some of its applications within high energy theory and condensed matter physics. We conclude with a discussion of how quantum field theory techniques may be useful in understanding the statistics of random ocean waves and the observed power law spectrum.

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Physics Colloquium of 6 February 2024
"QCD in space: quark matter with loop calculations"
Saga Saeppi, Technical University of Munich

From the point of view of a particle physicist, neutron stars are fascinating objects: They consist of strongly interacting matter at densities far higher than those achieved in terrestrial laboratories. They give us unique insight on the properties of quantum chromodynamics at finite densities, and a hope for a source of new physics with increasingly improving observations and theoretical descriptions. However, those theoretical descriptions provide exceptionally challenging: Lattice QCD, the usual gold-standard for theoretical information in the strongly coupled regime where neutron stars (and in particular their cores) lie ceases to work at finite density due to a fundamental obstacle known the sign problem. One of the few first-principles tools for describing dense matter is perturbative QCD. The methods of thermal field theory and effective field theories make this possible. Nevertheless, very high-order corrections are required in order to make pQCD applicable for this purpose. I will outline the computations needed for such improvements, in particular showing the diagrammatic methods needed to consistently perform finite-density computations in order to explain how advancements in recent years have made progressing even to next-to-next-to-next-to-leading order possible after a 40-year lull in progress.

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Physics Colloquium of 23 January 2024
"Summaries of 2023-2024 African School of Physics research visits"
Ketevi Assamagan et al., BNL

The African School of Physics (ASP) consists of series of activities to support the academic growth of African students and Early Career researchers. One such activity is the short-term research visits program where alumni of ASP spend 3-6 months at BNL for research. Nine ASP alumni came to BNL between July and December 2019. The program resumed in 2022 when 6 ASP alumni came to BNL for the period of August 2022 to February 2023. The 3rd cohort of 6 came to BNL for the period June 2023 - April 2024. They are placed within different research groups and assigned research advisors according to their majors and physics interests. This program is supported by DOE, the NPP DEIA Council and the departments and research groups that host participants.In this talk, we have short presentations by 4 alumni (cohort of 2023) on the work they have done during their stay at BNL:

1. Gloria Katunge Maithya (University of Nairobi, Kenya), EDG, "Quality Control (QC) Testing and Data Analysis of DUNE Detector Cold Electronics".

2. Aissata Ly (Cheikh Anta Diop University, Dakar, Senegal), Omega Group, "Quality control of ATLAS ITk stave alignment during assembly".

3. Fatima Bendebba (Hassan II University of Casablanca, Morocco), Omega Group, "Search for Higgs boson pair production in 2b + 2l + MET final states in pp collisions at sqrt(??) = 13 TeV with the ATLAS Experiment and Module Testing of the ATLAS Inner Tracker (ITK)".

4. Augustin Sokpor (University of Lome, Togo), Omega Group, "Development of equipment and setup aimed at testing novel AC-LGAD silicon detector".

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Physics Colloquium of 16 January 2024
"Quantum Computing on Classical Machines with Tensor Networks"
Miles Stoudenmire, Flatiron Institute

Quantum algorithms are sought after for their potential to outpace classical computing, but since the development of the first quantum algorithms almost 25 years ago, a new breed of classical algorithms has appeared that closely mimics quantum computers. These algorithms, based on tensor networks, provide scaling and capabilities similar to real quantum computers. Originally conceived for simulating small quantum systems or shallow circuits, in tensor networks can sometimes perform so well that they can even allow us to bring certain quantum algorithms back to the classical world, outperforming previously known classical algorithms on today's computers. After introducing tensor networks from a quantum computing perspective, I will discuss some recent efforts to simulate various quantum algorithms and reflect on the what the results tell us about the boundary between classical and quantum computing.

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Other Listings

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