Nuclear and Particle Physics Colloquium (NPPC)


Seminar Details

Mondays  4:00 PM

All seminars are hybrid
Building 26, 414 (Kolker Room)


Committee: Philip Harris, Chair ~ Alan Guth ~ Eluned Smith ~ Tracy Slatyer
Colloquia Archives

Spring 2024


hosted by:Tracy Slatyer     

Robert Jaffe 

The Prelude to the QCD Revolution

The is the historical talk I gave at the \50 Years of QCD" conference at UCLA last September. I describe the revolution in particle physics between 1962 and 1972 that led up to the formulation of QCD and the discovery of asymptotic freedom in 1973. The talk focuses on James Bjorken's seminal 1966 paper on the \Applications of the Chiral U(6)U(6) Algebra of Current Densities", the discoveries that led up to it, the confusion in the theory community that ensued,and the emergence of the quark-gluon paradigm that became QCD.





No Talk - Presidents Day




hosted by: Ronald Ruiz Garcia               

Eric Cornell  

Precision measurements are having a moment: recent results in g-2 and electric dipoles of leptons

The past three years have seen three dipole-moment measurements of record-breaking accuracy – the magnetic dipole moments (aka “g-2”) of the muon and of the electron, and the electric dipole moment (EDM) of the electron. I will focus in on the latter measurement, performed at the University of Colorado. Then I will try to compare and contrast the relative implications of all these three measurements for the search for Beyond Standard Model physics.




hosted by:Iain Stewart  

Johannes Henn

Positive geometry in particle physics and cosmology

There are strong indications from physics at both infinitesimal and cosmic distances that our current understanding of the laws of nature is only approximate, and must be replaced by deeper principles. Both in particle physics and in cosmology, novel geometric structure have made an appearance that hint at underlying mathematical structure. Many of these insights are driven by theoretical studies of scattering amplitudes -- the basic building blocks used to predict outcomes of particle scattering. In this talk I will review recent progress in this fascinating field.




hosted by:William Barletta 

Vladimir Shiltsev

Particle Colliders: Ultimate Limits and The Course Ahead

Particle colliders, indispensable tools for high-energy physics, are celebrating 60 years this spring. While the Large Hadron Collider and the Super-KEKB factory represent the frontier of hadron and lepton colliders today, respectively, future colliders are an essential component of a strategic vision for particle physics. Conceptual studies and technical developments for several exciting near- and medium-term future collider options are underway internationally.

Analysis of numerous proposals and studies for far-future colliders indicates the limits of collider beam technology due to machine size, cost, and power consumption. This calls for a paradigm shift in particle physics research at ultra-high energy but low luminosity colliders approaching or exceeding a 1 PeV center-of-mass energy scale.

The U.S. and international community of particle physicists and collider builders have defined the most important questions for the field and identified promising opportunities to address them. I will discuss the major recommendations of the Snowmass’21 Accelerator Frontier and briefly overview the key accelerators/colliders recommendations of the decadal report of the P5, Particle Physics Project Prioritization Panel (Dec. 2023).




hosted by:TBA 

Matt Durham

Mesons, baryons, and tetraquarks in the QCD medium at LHCb

One of the defining features of Quantum Chromodynamics is confinement, which prevents isolated quarks and gluons from being observed. Instead, partons are bound within a rich spectrum of hadrons, which have various quark content, binding energy, and size. With precision vertexing, full particle ID, and a fast DAQ, the LHCb detector can measure an unprecedented range of conventional and exotic hadrons. I will discuss recent LHCb results on mesons, baryons, and tetraquarks that are sensitive to the mechanisms enforcing confinement. In particular, I will show how these mechanisms are affected by the hadronic environment and discuss our understanding of hadronization in the QCD medium.





No Talk - Spring Break




hosted by:Elunded Smith  

Patrick Dunne  

A joint neutrino oscillation analysis of the T2K and NOvA experiments

Neutrino oscillation experiments are able to address some of the most pressing questions in modern physics. Notably, whether neutrinos violate CP symmetry, which could provide an explanation for the baryon asymmetry of the universe. Oscillation experiments are also sensitive to the neutrino mass ordering, ie, whether there are two light states and a heavier one (normal ordering) or vice versa (inverted ordering), the sizes of the mass differences between the neutrinos, and details related to the structure of neutrino mass/flavor mixing. This talk will present the first joint analysis of data sets from T2K and NOvA, the two currently operating long-baseline neutrino oscillation experiments. We take advantage of the experiments’ complementary designs to lift degeneracies in parameter space and set new constraints on a number of neutrino sector parameters. This analysis provides new precision on ∆m232, as well as giving a 3σ interval on δCP of [-4.34,0.94] ([-2.89,-0.13]) in the normal (inverted) ordering. The data shows no strong preference for either mass ordering. However, if another experiment were to show the inverted ordering to be true, then our results would provide evidence of CP symmetry violation in the neutrino sector.





No Talk





No Talk - Patriot's Day




hosted by:Janet Conrad  

Cathy Cutler 

50 years of Isotope Production via High Energy Accelerators at Brookhaven National Laboratory

In February 1972 the Brookhaven Linac Isotope Producer (BLIP) came online to accept protons from the 200 MeV Linac that synergistically supports multiple programs including the isotope production program, the Nasa Space Radiation Laboratory (RHIC) as well as the Relativistic Hadron Ion Collider (RHIC).  In addition to the BLIP the isotope program operates the Radionuclide Research and Production Laboratory (RRPL) which contains laboratories and hot cells for processing targets irradiated at the BLIP for external customers as well as internal research. New hot cells have been brought online to aid in the processing of Ac-225. The BLIP allows the production of isotopes from 200 MeV and down in energies using stacked target arrays that allows for multiple isotope production. High energy accelerators play a critical role in supplying radionuclides such as Sr-82 used in Sr-82/Rb-82 generators for cardiac imaging.  They continue to be upgraded to further production yields by installing beam rastering systems that have allowed higher intensities and thus higher production yields.  Demand for isotopes that can be produced by these systems have also increased.  Linear accelerators such as the one at Brookhaven National Laboratory when operating at maximum proton energy of 200 MeV can have simultaneous production of several medically relevant isotopes. Among those are Ac-225 (T1/2=10.0 d), Cu-67 (T1/2=64.83 h), Se-72/As-72 (T1/2=26 h), Sr-82/Rb-82 (T1/2=1.26 min) and Ti-44/Sc-44 (T1/2=3.97 h).  Discussion of recent facility enhancements and future upgrades and production of novel radionuclides will be presented.




hosted by:Phillip Harris  

Jennifer Roloff

Any way you slice it: The Lund jet plane as a unique probe of QCD

Jet substructure is a versatile tool which has been applied to identify jets originating from different particles, enabling a wide range of searches and measurements at the LHC. Beyond simply tagging jets, it is also a sensitive probe of QCD across a wide range of energy scales, giving insight into the formation and evolution of jets. While a useful tool, jet substructure is notoriously difficult to describe, and mismodeling of this rich inner structure limits its effectiveness. In this talk, I will discuss how measurements of jet substructure are being used to better understand jet formation and to provide new tests of our theoretical descriptions of these models. In particular, I will cover how measurements of the Lund jet plane have provided a new framework for testing different theoretical effects. I will then use the example of a recent measurement by the ATLAS experiment of the Lund subjet multiplicity to illustrate how these measurements can provide precision tests of parton shower models, enabling more advanced descriptions of jet formation.




hosted by:Tracey Slatyer 

Nicholas Rodd

Echos of the Early Universe in Axion Haloscopes

The coming decade will bring dramatic improvement in the axion dark-matter program as new experimental designs move beyond the proof of principle stage. In this talk I will outline two signals beyond dark matter that these instruments could discover. The first is a population of relativistic axions that were produced in the early universe and persist as a residual Cosmic axion Background (CaB). The second is high-frequency gravitational waves; I will outline how exploiting an analogy between axion and gravitational-wave electrodynamics allows for axion haloscopes to be converted into gravitational-wave telescopes. Axion instruments could even be used to detect individual gravitons, and I will end with a brief comment on what this would imply for the quantum nature of gravity.




hosted by:Tracy Slatyer  

Priya Natarajan

New Windows into Supermassive Black Holes in the Universe

There is a revolution afoot in our understanding of supermassive black holes (SMBHs), that is reshaping our view of their formation, growth and influence on cosmic architecture. This talk will spotlight three recent breakthroughs that have enriched our knowledge of their origins, mass assembly histories and coupling to the larger scale galactic environments. These include: (i) unveiling black hole seed formation via direct collapse illuminated by the synergistic capabilities of NASA's JWST, Chandra, and Hubble telescopes; (ii) groundbreaking evidence for the collective gravitational wave signals from merging SMBHs, captured by the global network of pulsar timing arrays, including NANOGrav; and (iii) the advent of cutting-edge computational methods enabling us to integrate the dynamics of SMBH accretion with their extended cosmic environments. These advancements signify a major leap forward in tackling the key open questions in black hole physics. The talk will conclude by exploring the horizons of this scientific renaissance, and prospects for the future including the upcoming LISA mission.