Biography
Christian Bauer received his undergraduate education in Karlsruhe, Germany, and his PhD from the University of Toronto under Michael Luke. After graduating in 2000, he took a postdoc position at UC San Diego. In 2003 he moved to Caltech as a McCone senior research fellow and joined the LBNL theory group in 2005 as a Divisional Fellow to LBNL. Since 2006 he has been Senior Staff Scientist. In 2005 he received an Outstanding Junior Investigator award, and in 2010 an Early Career Award from the Department of Energy. In 2010 he was the recipient of the Presidential Early Career Award. Since 2018 he is the head of the Theory Group.
Research interests
Much of my research in the past has focused on the development of novel calculational techniques to increase our ability to make precise predictions in the standard model. Effective field theories are a wonderful tool to work in realistic situations, where widely separated scales make perturbation theory slowly converging, or where non-perturbative effects become important.
One of my major accomplishments is the development of Soft-collinear effective theory (SCET). This Effective Theory has been applied to many different problems in particle physics, mostly in the context of collider physics. One of the most important applications is the ability to derive and prove factorization theorems, which allow to separate non-perturbative long distance physics from perturbative short distance physics, allowing to identify and extract challenging non-perturbative ingredients in predictions of collider physics.
I have been involved in the effort to improve the accuracy of event generators at fixed order. This has led to the development of the GENEVA Monte Carlo. The major difference compared to any other event generators currently on the market or under development, is that GENEVA does not only include higher fixed order accuracy, but higher logarithmic accuracy as well. Many high profile analyses such as H -> WW require jet vetoes to control the backgrounds, and higher logarithmic resummation has been shown to be of crucial importance to reduce theoretical uncertainties to a level comparable with experimental uncertainties. GENEVA is therefore be of vital importance to provide fully exclusive predictions in such restricted regions of phase space.
Recently I have started to work on the rapidly growing field of Quantum Computing (QC), with an eye towards applications of QC to High Energy Physics, and making currently available Noisy Intermediate Scale Quantum (NISQ) devices more reliable. My group has had important contributions on a variety of different fronts. We have developed quantum algorithms for parton showers, which can include certain quantum interference that are exponentially difficult to include with many showers. We have also devised several methods for the mitigation of gate and readout errors, with these methods being crucial to obtain reliable results from current NISQ hardware. Another important development of my group was to show that non-perutbative matrix elements of SCET, which are not easily extracted from experimental measurements can be calculated efficiently using quantum computers. Most of the research of my group, however, is in the field of Hamiltonian Lattice Field Theory. It has been shown that quantum computers provide exponential advantage over classical computers to simulate the dynamics of field theories using this approach, and we have derived a variety of different formulations of gauge theories in this framework. Most notable are the developments allowing to work in the small coupling limit (which matters to take the continuum limit of the lattice field theory), and our work on SU(3) gauge theory in the large Nc limit, which has allowed simulations of this theory on large 2-dimensional lattices for the first time.
Selected publications
(Full list of publications can be found here.)
Gauge Loop-String-Hadron Formulation on General Graphs and Applications to Fully Gauge Fixed Hamiltonian Lattice Gauge Theory,
with I. M. Burbano, [arXiv:2409.13812]
Block encoding by signal processing,
with C. F. Kane, S. Hariprakash, N. S. Modi, M. Kreshchuk, [arXiv:2408.16824]
Quantum Simulation of SU(3) Lattice Yang-Mills Theory at Leading Order in Large-Nc Expansion,
with A. Ciavarella, PRL 133 (2024) 11, 111901 [arXiv:2402.10265]
New basis for Hamiltonian SU(2) simulations,
with I. D’Andrea, M. Freytsis, D. Grabowska, Phys.Rev.D 109 (2024) 7, 074501 , [arXiv:2307.11829]
Quantum Computing for High-Energy Physics: State of the Art and Challenges,
with A. Di Meglio et al, PRX Quantum 5 (2024) 3, 037001, [arXiv:2307.03236]
Quantum simulation of fundamental particles and forces,
with Z. Davoudi, N. Klco, M. Savage, Nature Rev.Phys. 5 (2023) 7, 420-432, [arXiv:2404.06298]
Quantum Simulation for High-Energy Physics,
co-edited with Z. Davoudi, PRX Quantum 4 (2023) 2, 027001, [arXiv:2204.03381]
Efficient representation for simulating U(1) gauge theories on digital quantum computers at all values of the coupling,
with D. Grabowska, Phys.Rev.D 107 (2023) 3, L031503, [arXiv:2111.08015]
Dark Matter Spectra from the Electroweak to the Planck Scale,
with N. L. Rodd and B. R. Webber, [arXiv:2007.15001]
Zero-noise extrapolation for quantum-gate error mitigation with identity insertions,
with A. He, B. Nachman, W. A. de Jong, PRA 102 (2020) 1, 012426, [arXiv:2003.04941]
Unfolding Quantum Computer Readout Noise,
with B. Nachman, M. Urbanek, W. A. de Jong, [arXiv:1910.01969]
A quantum algorithm for high energy physics simulations,
with W. A. de Jong, B. Nachman, D. Provasoli, [arXiv:1904.03196]
A numerical formulation of resummation in effective field theory,
with P. F. Monni, arXiv:2007.04320]
Standard Model Parton Distributions at Very High Energies,
with N. Ferland and B. R. Webber, JHEP 1708 (2017) 036, [arXiv:1703.08562]
Drell-Yan Production at NNLL’+NNLO Matched to Parton Showers,
with S. Alioli, C. Berggren, F. J. Tackmann, J. R. Walsh, PRD 92, 094020 [arXiv:1508.01475]
Factorization and Resummation for Dijet Invariant Mass Spectra ,
with F. J. Tackmann, J. R. Walsh, S. Zuberi, PRD 85, 074006, [arXiv:1106.6047]
Factorization of e+e- Event shape distributions with Hadronic Final States in SCET
with S. P. Fleming, C. Lee, G. F. Sterman, PRD 78, 034027, [arXiv:hep-ph/0801.4569]
Event Generation from Effective Field Theory,
with M. D. Schwartz, PRD 76, 074004 [arXiv:hep-ph/0607296].
Soft collinear factorization in effective field theory,
with D. Pirjol, I. W. Stewart, PRD 65, 054022, [arXiv:hep-ph/0109045].
An effective theory for collinear and soft gluons: Heavy to light decays,
with S. Fleming, D. Pirjol, I. W. Stewart, PLB 516 (2001) 134-142, [arXiv:hep-ph/0011336].
Summing Sudakov logarithms in B->Xs γ in effective field theory,
with S. Fleming, M. E. Luke, PRD 63 (2000) 014006, [arXiv:hep-ph/0005275].