Welcome to the homepage of
Christopher Plumberg
Assistant Professor of Physics
at Pepperdine University
Assistant Professor of Physics
at Pepperdine University
I am a theoretical physicist whose research focuses on particle physics and high-energy nuclear physics. I am currently an assistant professor of physics at Pepperdine University in Malibu, California. In addition to physics, I am very interested in topics related to the philosophy of physics, the philosophy of science, and the philosophy of mathematics.
Here's a little more information about me. I live in California, USA, with my wife and two young children.
The big idea: I explore the properties of this force at very high temperatures and densities by studying and modelling collisions between nuclei at the speed of light. I focus on advanced statistical techniques to analyse the large datasets of collected information, both from colliders and collision simulators, in order to confirm and predict aspects of the collisions' structures. My work relies heavily on both analytical and computational methods to describe and simulate various aspects of these nuclear collisions.
Some keywords: Relativistic heavy-ion collisions, hydrodynamic fluctuations, Hanbury Brown-Twiss (HBT) interferometry, quantum chromodynamics (QCD), the QCD phase diagram and the critical endpoint (CEP), event generators
Here's some of my background and previous experience.
Aug 2022 - Present
Location: Malibu, California, USA
Sep 2020 - July 2022
Supervisor: Jaki Noronha-Hostler
Location: Urbana, Illinois, USA
Focus: heavy-ion event generators, collectivity in small systems, α-clustering in oxygen-oxygen collisions, relativistic hydrodynamics and causality
Sep 2018 - Sep 2020
Supervisor: Leif Lönnblad
Location: Lund, Sweden
Focus: heavy-ion event generators, collectivity in small systems
Aug 2016 - Aug 2018
Supervisor: Prof. Joseph Kapusta
Location: Minneapolis, Minnesota, USA
Focus: relativistic hydrodynamics and hydrodynamic fluctuations, Hanbury-Brown--Twiss (HBT) interferometry, AdS/QCD, conserved-charge fluctuations and correlations
May 2009 - August 2009
REU/NSF Summer Program
Topic: Developed tomographic software for analyzing STEREO and TRACE data of solar corona
Advisor: Prof. Charles Kankelborg
May 2008 - August 2008
REU/NSF Summer Program
Topic: Fluxon modeling of magnetohydrodynamic phenomena on solar corona and photosphere
Advisor: Prof. Charles Kankelborg
Spring 2020
Topic: Classical Mechanics and Special Relativity
Oct 2016
Topic: Graduate Statistical Physics
Sep 2009 - May 2013
Topics: Introductory Physics, Freshman Engineering Honors, Intermediate Mechanics
Sep 2012 - Jul 2016
Thesis Topic: Azimuthally sensitive and event-by-event Hanbury Brown-Twiss analyses
Advisor: Prof. Ulrich W. Heinz
Area of Study: Relativistic heavy-ion collisions
Sep 2009 - Aug 2012
Candidacy Topic: Constraints on Supersymmetry from \(B_s \rightarrow \mu^+ \mu^-\)
Advisor: Prof. Stuart A. Raby
Area of Study: Model building and collider phenomenology
Sep 2005 - May 2009
Major: Astronomy and Astrophysics (Magna Cum Laude)
Templeton Honors College graduate
Advisor: Prof. David H. Bradstreet
Here is a selection of some of my most recent papers. You can find a more complete list here.
It is sometimes believed that small quantum gravity effects can encode information as ‘delicate correlations’ in Hawking radiation, thus saving unitarity while maintaining a semi classical horizon. A recently derived inequality showed that this belief is incorrect: one must have order unity corrections to low energy evolution at the horizon (i.e. fuzzballs) to remove entanglement between radiation and the hole. In this paper we take several models of ‘small corrections’ and compute the entanglement entropy numerically; in each case this entanglement is seen to monotonically grow, in agreement with the general inequality. We also construct a model of ‘burning paper’, where the entanglement is found to rise and then return to zero, in agreement with the general arguments of Page. We then note that the fuzzball structure of string microstates offers a version of ‘complementarity’. Low energy evolution is modified by order unity, resolving the information problem, while for high energy infalling modes (E?\(\gg\)?kT) we may be able to replace correlators by their ensemble averaged values. Israel (and others) have suggested that this ensemble sum can be represented in the thermo-field-dynamics language as an entangled sum over two copies of the system, giving the two sides of the extended black hole diagram. Thus high energy correlators in a microstate may be approximated by correlators in a spacetime with horizons, with the ensemble sum over microstates acting like the ‘sewing’ prescription of conformal field theory.
The PHENIX Collaboration has reported third-order harmonic oscillations of the source radius parameters when measuring the Hanbury Brown-Twiss correlation function for charged hadrons relative to the triangular flow angle. We explore possible origins of such third-order oscillations with a simple Gaussian source featuring both a triangular geometric deformation and triangular flow. Third-order oscillations of the HBT radii can arise from a purely geometric triangular deformation superimposed on an azimuthally symmetric radial flow, or from a radially symmetry spatial distribution which expands anisotropically with a triangular component in the flow velocity profile. In both cases the final particle momentum distribution features triangular flow. We show that the two alternatives can be distinguished experimentally through the phase of the azimuthal oscillations of the HBT radii relative to the triangular flow plane.
We study the propagation and diffusion of electric charge fluctuations in high-energy heavy-ion collisions using the Cattaneo form for the dissipative part of the electric current. As opposed to the ordinary diffusion equation this form limits the speed at which charge can propagate. Including the noise term in the current, which arises uniquely from the fluctuation-dissipation theorem, we calculate the balance functions for charged hadrons in a simple 1+1-dimensional Bjorken hydrodynamical model. Limiting the speed of propagation of charge fluctuations increases the height and reduces the width of these balance functions when plotted versus rapidity. We also estimate the numerical value of the associated diffusion time constant from antide Sitter-space/conformal-field theory.
Hanbury Brown-Twiss correlation functions and radii from event-by-event hydrodynamics (HoTCoffeeh) is a new computational tool which determines Hanbury Brown-Twiss (HBT) charged-pion (π+) correlation functions and radii for event-by-event hydrodynamics with fluctuating initial conditions in terms of CooperFrye integrals, including resonance-decay contributions. In this paper, we review the basic formalism for computing the HBT correlation functions and radii with resonance-decay contributions included and discuss our implementation of this formalism in the form of HoTCoffeeh. This tool may easily be integrated with other numerical packages [see, e.g., Comput. Phys. Commun. 199, 61 (2016)] for the purpose of simulating the evolution of heavy-ion collisions and thereby extracting predictions for heavy-ion observables.
Here are the best ways to get in touch with me.
Loomis Laboratory of Physics
University of Illinois at Urbana-Champaign
1110 W Green St
Urbana, IL 61801
christopher.plumberg (at) gmail.com
