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Research

My research interests are all connected by lattice field theory, but they span several topics within high energy theory and software development. I try to describe each project and link some relevant literature. A complete list of literature can be found on InspireHEP.

HVP contribution to muon anomalous magnetic moment

The muon anomalous magnetic moment \(a_\mu\) has been measured to extremely high precision, most recently at Fermilab by the Muon \(g-2\) collaboration. On the theoretical side, it can be subdivided into QED, electroweak, and hadronic contributions, the latter of which cannot be obtained perturbatively. The hadronic vacuum polarization (HVP) contribution can be computed using lattice QCD or using the dispersive method, a data-driven approach that takes experimentally measured cross sections as input. \(a_\mu\) has been of particular interest to the community, as state-of-the-art experimental results compared to theoretical results extracted using the dispersive approach exhibited about \(4.2\sigma\) tension in 2020. If that discrepancy were confirmed, it may indicate another possible signal for physics beyond the Standard Model (SM). Since then, a lattice determination by the BMW Collaboration fell between the dispersive and experimental results, which has been updated to favor the experimental result, albeit using some additional experimental input. Meanwhile the situation for the dispersive approach has become somewhat ambiguous, as new measurements from CMD-3 lie in tension with older results. Independent lattice input is urgently needed, and I help the Fermilab-HPQCD-MILC collaboration to that end.

Publications
  • 2025: R. Aliberti, T. Aoyama, E. Balzani, A. Bashir, G. Benton et al. "The anomalous magnetic moment of the muon in the Standard Model: an update", Phys. Rep., 1143, DOI: 10.1016/j.physrep.2025.08.002 arXiv: 2505.21476.
  • 2024: A. Bazavov, C. W. Bernard, D. A. Clarke, C. T. H. Davies, C. DeTar et al. "Hadronic vacuum polarization for the muon \(g-2\) from lattice QCD: Long-distance and full light-quark connected contribution", Phys. Rev. Lett, 135, DOI: 10.1103/d583-yhfs arXiv: 2412.18491.
  • 2024: A. Bazavov, D. A. Clarke, C. T. H. Davies, C. DeTar, A. X. El-Khadra et al. "Hadronic vacuum polarization for the muon \(g-2\) from lattice QCD: Complete short and intermediate windows", Phys. Rev. D, 111, DOI: 10.1103/PhysRevD.111.094508 arXiv: 2411.09656.
Presentations

QCD phase diagram

The phase diagram of strongly interacting matter in the plane of temperature \(T\) and net-baryon chemical potential \(\mu_B\) has been under active study for some decades. Its landscape has implications for the evolution of the early universe, the content of neutron-star cores, and understanding non-perturbative aspects of the QCD Lagrangian. It was recognized relatively early on that there is a temperature threshold, the Hagedorn temperature, beyond which strongly interacting systems are not described well by the thermodynamics of ordinary nuclear matter. Since then, the community has mapped out many features of the diagram: broadly, there is a hadron-gas phase at low \(T\) and/or \(\mu_B\) and a quark-gluon-plasma phase for high \(T\) and/or \(\mu_B\). For sufficiently small \(\mu_B\), this phase change is a crossover. At large enough \(\mu_B\) the phases are expected to be separated by a first-order line. There has been substantial effort both theoretical and experimental in the form of heavy-ion collisions (HICs) to find the critical endpoint (CEP) at which the first-order line terminates. My research uses a variety of approaches to put bounds on the location of the CEP using lattice QCD. I also compute other properties of the medium, e.g. its material parameters or how observables scale approaching various transition points, especially for initial conditions similar to those in HICs.

Publications

  • 2025: D. A. Clarke, P. Dimopoulos, F. Di Renzo, J. Goswami, C. Schmidt et al. "Searching for the QCD critical point using multi-point Padé approximations", Phys. Rev. D, 112, DOI: 10.1103/y6kg-ry8x arXiv: 2405.10196.

  • 2025: D. A. Clarke, J. Goswami, F. Karsch, and P. Petreczky. "A generalized definition of the isothermal compressibility in (2+1)-flavor QCD", arXiv: 2506.22816.

  • 2024: D. A. Clarke, P. Dimopoulos, F. Di Renzo, J. Goswami, C. Schmidt et al. "Searching for the QCD critical point using Lee-Yang edge singularities", 453 PoS(LATTICE2023)168, DOI: 10.22323/1.453.0168 arXiv: 2401.08820.

  • 2024: D. A. Clarke, J. Goswami, F. Karsch, and P. Petreczky. "QCD material parameters at zero and non-zero chemical potential from the lattice", EPJ Web Conf. 296 (2024) 14005 DOI: 10.1051/epjconf/202429614005 arXiv: 2312.16703.

  • 2023: D. Bollweg, D. A. Clarke, J. Goswami, O. Kaczmarek, F. Karsch et al.
    "Equation of state and speed of sound of (2+1)-flavor QCD in strangeness-neutral matter at non-vanishing net baryon-number density", Phys. Rev. D, 108, DOI: 10.1103/PhysRevD.108.014510 arXiv: 2212.09043.

  • 2022: D. A. Clarke. "Isothermal and isentropic speed of sound in (2+1)-flavor QCD at non-zero baryon chemical potential", 430 PoS(LATTICE2022)147, DOI: 10.22323/1.430.0147 arXiv: 2212.10009.

  • 2021: D. A. Clarke, O. Kaczmarek, F. Karsch, A. Lahiri, and M. Sarkar. "Imprint of chiral symmetry restoration on the Polyakov loop and the heavy quark free energy", 396 PoS(LATTICE2021)184, DOI: 10.22323/1.396.0184 arXiv: 2111.09844.

  • 2021: D. A. Clarke, O. Kaczmarek, A. Lahiri, and M. Sarkar. "Sensitivity of the Polyakov loop to chiral symmetry restoration", Acta Phys. Pol. B Proc. Suppl. 14, 311 DOI: 10.5506/APhysPolBSupp.14.311 arXiv: 2010.15825.

  • 2021: D. A. Clarke, O. Kaczmarek, F. Karsch, A. Lahiri, and M. Sarkar. "Sensitivity of the Polyakov loop and related observables to chiral symmetry restoration", Phys. Rev. D, 103 DOI: 10.1103/PhysRevD.103.L011501 arXiv: 2008.11678.

Presentations

Deep learning phases of matter

Deep learning has proven capable of distinguishing phases of matter in classical statistical physics systems. For example the output layer of a convolutional neural network can be treated as an effective order parameter and used to extract critical parameters. We explore the capabilities and limitations of deep learning with the eventual goal of examining the width of the QCD crossover transition.

Publications
  • 2025: A. Abuali, D. A. Clarke, M. Hjorth-Jensen, I. Konstantinidis, C. Ratti et al. "Deep learning of phase transitions with minimal examples", Phys. Rev. E, 112, DOI: 10.1103/wjvx-5nk7 arXiv: 2501.05547.

Software development

SIMULATeQCD is a (Si)mple, (Mu)lti-GPU (Lat)ice code for (QCD) calculations, is a multi-GPU, multi-node, highly modularized code base, written using modern C++. It supports \(N_f=2+1\) HISQ and pure SU(3) gauge actions, and it includes modules for measurement of various observables. It can run on both NVIDIA and AMD GPUs.

The AnalysisToolbox is a set of Python tools for analyzing physics data, in particular targeting lattice QCD. It includes statistics modules, such as general jackknife and bootstrap error bar calculators; physics modules, for instance allowing hadron resonance gas model calculations; and it also includes moderate interfacing with HotQCD and MILC software.

Publications

  • 2023: L. Altenkort, D. A. Clarke, J. Goswami, H. Sandmeyer. "Streamlined data analysis in Python", 453 PoS(LATTICE2023)136, DOI: 10.22323/1.453.0136 arXiv: 2308.06652.

  • 2023: L. Mazur, D. Bollweg, D. A. Clarke, L. Altenkort, O. Kaczmarek et al. "SIMULATeQCD: A simple multi-GPU lattice code for QCD calculations", Comput. Phys. Commun, 300, DOI:10.1016/j.cpc.2024.109164, arXiv:2306.01098.

  • 2021: D. Bollweg, L. Altenkort, D. A. Clarke, O. Kaczmarek, L. Mazur et al. "HotQCD on Multi-GPU Systems", 396 PoS(LATTICE2021)196, DOI: 0.22323/1.396.0196 arXiv: 2111.10354.