About

Csaba Csaki is the John A. Newman Professor of Physical Sciences at Cornell University, specializing in elementary particle theory with a focus on physics beyond the standard model. His research aims to understand plausible theories that extend the standard model and their experimental consequences, particularly in light of ongoing LHC collider experiments. His work explores two main directions: theories with extra spatial dimensions, which could introduce new mechanisms for electroweak symmetry breaking, and supersymmetry, a symmetry relating fermionic and bosonic particles that offers elegant extensions of the standard model. Csaki's academic background includes a B.Sc. in Physics from Eötvös University in Budapest and a Ph.D. in Physics from MIT. He has held positions at Cornell University since 2002, progressing from Assistant Professor to Professor of Physics. His contributions to the field include advancing understanding of elementary particle physics and contributing to the theoretical framework that guides experimental investigations into the fundamental nature of matter.

Research topics

• Physics
• Particle physics
• Theoretical physics
• Mathematical physics
• Astrophysics
• Quantum mechanics
• Quantum electrodynamics

Selected publications

• $θ$ Angle and Axial Anomaly in Holographic QCD

  arXiv (Cornell University) · 2026-03-26

  preprintOpen access1st authorCorresponding

  We present a bottom-up holographic description of the QCD $θ$-vacuum and the $U(1)_A$ anomaly in five dimensions. The multi-branched $θ$-vacuum structure emerges geometrically from a higher-dimensional gauge field, while the axial anomaly is realized through a Stückelberg coupling that is dual to a Chern-Simons term. In this framework, the $η'$ meson appears as a zero mode of bulk fluctuations, and its mass arises from the anomaly-induced Stückelberg term. The construction provides a transparent holographic derivation of the anomaly contribution to the $η'$ mass and naturally reproduces the Witten-Veneziano relation between the $η'$ mass and the Yang-Mills topological susceptibility.

  PublisherDOI

• The Holographic QCD Axion in Five Dimensions

  arXiv (Cornell University) · 2026-04-02

  preprintOpen access1st authorCorresponding

  We present a holographic construction of the QCD axion based on a warped 5D model. A key ingredient of our setup is the introduction of a bulk scalar field $θ$, which is holographically dual to the topological operator of QCD. This makes the relation among the axion, the $η'$, and the anomalies transparent. We identify the bulk modes corresponding to the $η'$ and axion states, and show that an adjustment analogous to that of the usual 4D axion takes place. We identify the origin of the axion quality problem in this framework and show that a large degree of axion compositeness is needed to solve it. We also find that, in the limit of a high quality axion, the physical axion state is predominantly contained in the bulk gauge field.

  PublisherDOI

• Electroweak precision constraints on dark photon models with generalized mixing

  Journal of High Energy Physics · 2026-03-16

  articleOpen access

  A bstract We present a global fit to electroweak precision observables (EWPOs) in dark photon (DP) models containing both kinetic and mass mixing between the DP and the neutral gauge bosons of the Standard Model (SM). Such more general mixing can be the result of an extended scalar sector, which we specify in this paper. We calculate the tree-level contributions to EWPOs due to the mixing with the DP, as well as the leading loop corrections to the oblique parameters due to the extended Higgs sector. In the scalar sector, we find that ample regions of parameter space are still unconstrained by data. In the gauge sector, the excluded region depends strongly on the vacuum expectation values of the scalar fields: for moderate ratios, DP masses in the (40 GeV, 1 TeV) range are excluded; for larger ratios, the limits become indistinguishable from those for standard DPs.

  PublisherDOI

• The Holographic QCD Axion in Five Dimensions

  arXiv (Cornell University) · 2026-04-02

  articleOpen access1st authorCorresponding

  We present a holographic construction of the QCD axion based on a warped 5D model. A key ingredient of our setup is the introduction of a bulk scalar field $θ$, which is holographically dual to the topological operator of QCD. This makes the relation among the axion, the $η'$, and the anomalies transparent. We identify the bulk modes corresponding to the $η'$ and axion states, and show that an adjustment analogous to that of the usual 4D axion takes place. We identify the origin of the axion quality problem in this framework and show that a large degree of axion compositeness is needed to solve it. We also find that, in the limit of a high quality axion, the physical axion state is predominantly contained in the bulk gauge field.

  PublisherOA PDF

• $θ$ Angle and Axial Anomaly in Holographic QCD

  ArXiv.org · 2026-03-26

  articleOpen access1st authorCorresponding

  We present a bottom-up holographic description of the QCD $θ$-vacuum and the $U(1)_A$ anomaly in five dimensions. The multi-branched $θ$-vacuum structure emerges geometrically from a higher-dimensional gauge field, while the axial anomaly is realized through a Stückelberg coupling that is dual to a Chern-Simons term. In this framework, the $η'$ meson appears as a zero mode of bulk fluctuations, and its mass arises from the anomaly-induced Stückelberg term. The construction provides a transparent holographic derivation of the anomaly contribution to the $η'$ mass and naturally reproduces the Witten-Veneziano relation between the $η'$ mass and the Yang-Mills topological susceptibility.

  PublisherOA PDF

• Ultralight Dilatonic Dark Matter

  Journal of High Energy Physics · 2026-04-20

  articleOpen access

  A bstract The dilaton, a pseudo-Nambu-Goldstone boson (pNGB) of broken scale invariance, is an appealing ultralight dark matter (DM) candidate. Its mass is protected by conformal invariance and it can be searched for in tabletop experiments. However, contrary to standard pNGBs of internal symmetries, the dilaton generically has a large non-derivative self-coupling, leading to radiative contributions to its mass of the order of its decay constant. Hence typical ultralight dilatons should also have sub-eV decay constants, which would incur significant deviations from standard DM behavior at structure formation times, in severe tension with observations. Therefore, a fine-tuning is required to generate a hierarchy between the mass and the decay constant. In this work, we consider whether supersymmetry (SUSY) can be used to protect this hierarchy from quantum corrections. To ensure an ultralight dilaton mass robust against realistic SUSY-breaking contributions, we must consider a novel dilaton stabilization mechanism. The observed DM abundance can be produced by the misalignment mechanism for dilaton masses ranging from 10 −11 to 1 eV. Unfortunately, irreducible SUSY-breaking corrections due to gravity restrict the couplings between the dilaton and the Standard Model to be extremely small, beyond the reach of any current or proposed experiments. Our work demonstrates that constructing a consistent model of ultralight dilaton DM is quite involved.

  PublisherOA PDFDOI

• Electroweak precision constraints on dark photon models with generalized mixing

  Journal of High Energy Physics · 2026-03-16

  articleOpen access

  A bstract We present a global fit to electroweak precision observables (EWPOs) in dark photon (DP) models containing both kinetic and mass mixing between the DP and the neutral gauge bosons of the Standard Model (SM). Such more general mixing can be the result of an extended scalar sector, which we specify in this paper. We calculate the tree-level contributions to EWPOs due to the mixing with the DP, as well as the leading loop corrections to the oblique parameters due to the extended Higgs sector. In the scalar sector, we find that ample regions of parameter space are still unconstrained by data. In the gauge sector, the excluded region depends strongly on the vacuum expectation values of the scalar fields: for moderate ratios, DP masses in the (40 GeV, 1 TeV) range are excluded; for larger ratios, the limits become indistinguishable from those for standard DPs.

  PublisherDOI

• Holographic energy correlators for soft walls

  Journal of High Energy Physics · 2025-07-09 · 6 citations

  articleOpen access1st authorCorresponding

  A bstract We calculate energy correlators in a general holographic model of confinement, involving an asymptotically anti-de Sitter (AdS) warped extra dimension. Building on a recent computation in a minimal hard-wall model of confinement, we show that the shockwave method for efficiently computing energy correlators in AdS generalizes to an arbitrary warped geometry. This is possible because exact, linear shockwave solutions to the 5D field equations exist in any warped background. We apply our formalism to compute the two-point energy correlator for two simple models of confinement with interesting infrared spectra — one with a gapped continuum spectrum and one with linear Regge trajectories. The results differ from the simple hard-wall model and from each other, demonstrating that the details of the confining dynamics affect the shape of the energy correlator observables.

  PublisherOA PDFDOI

• A cosmological solution to the doublet-triplet splitting problem

  Journal of High Energy Physics · 2025-02-11 · 4 citations

  articleOpen access1st authorCorresponding

  A bstract We propose a model that provides a simultaneous solution to the doublet-triplet splitting problem of grand unified theories, the electroweak hierarchy problem and the strong CP problem. The mechanism is based on the dynamics of two axion-like particles that would crunch the universe at the time of the QCD phase transition if triplets were light or had a VEV or if doublets were heavy or did not have a VEV. The only trace left at low energies are these two axion-like particles. They are weakly coupled to the Standard Model and could be detected at upcoming axion experiments or by a combination of neutron EDM measurements and the astrophysical detection of fuzzy dark matter.

  PublisherOA PDFDOI

• Phase transitions at unusual values of θ

  Journal of High Energy Physics · 2025-12-01

  articleOpen access1st author

  A bstract We calculate the θ dependence in a cousin of QCD, where the vacuum structure can be analyzed exactly. The theory is $$ \mathcal{N} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> </mml:math> = 2 SU(2) gauge theory with N F = 0, 1, 2, 3 flavors of fundamentals, explicitly broken to $$ \mathcal{N} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>N</mml:mi> </mml:math> = 1 via an adjoint superpotential, and coupled to anomaly mediated supersymmetry breaking (AMSB). The hierarchy m AMSB ≪ μ 𝒩=1 ≪ Λ ensures the validity of our IR analysis. As expected from ordinary QCD, the vacuum energy is a function of θ which undergoes 1st order phase transitions between different vacua where the various dyons condense. For N F = 0 we find the expected phase transition at θ = π , while for N F = 1, 2, 3 we find phase transitions at fractional values of π .

  PublisherOA PDFDOI

Recent grants

• Elementary Particle Theory

  NSF · $1.9M · 2014–2017

• Theoretical Particle Physics

  NSF · $1.8M · 2017–2021

• Theoretical Particle Physics

  NSF · $3.3M · 2009–2014

• Theoretical Particle Physics

  NSF · $2.2M · 2020–2024

Frequent coauthors

• John Terning

  University of California, Davis

  102 shared

• Christophe Grojean

  48 shared

• Hitoshi Murayama

  Kavli Institute for the Physics and Mathematics of the Universe

  42 shared

• Brando Bellazzini

  CEA Paris-Saclay

  32 shared

• Ofri Telem

  32 shared

• Raffaele Tito D’Agnolo

  Centre National de la Recherche Scientifique

  32 shared

• Yuri Shirman

  University of California, Irvine

  29 shared

• Jing Shu

  Peking University

  22 shared

Labs

• Department of Physics, Cornell UniversityPI

Awards & honors

• Miller Fellow, UC Berkeley, 1997-1999
• J. Robert Oppenheimer Fellow, Los Alamos National Laboratory…
• DOE Outstanding Junior Investigator, 2001-2007