Publications

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• Twisted gauging and topological sectors in (2+1)d Abelian lattice gauge theories

  Bram Vancraeynest-De Cuiper, Clement Delcamp

  SciPost Phys. 19, 054 (2025) · published 22 August 2025 | Toggle abstract · pdf

  Given a two-dimensional quantum lattice model with an Abelian gauge theory interpretation, we investigate a duality operation that amounts to gauging its invertible 1-form symmetry, followed by gauging the resulting 0-form symmetry in a twisted way via a choice of discrete torsion. Using tensor networks, we introduce explicit lattice realisations of the so-called condensation defects, which are obtained by gauging the 1-form symmetry along submanifolds of spacetime, and employ the same calculus to realise the duality operators. By leveraging these tensor network operators, we compute the non-trivial interplay between symmetry-twisted boundary conditions and charge sectors under the duality operation, enabling us to construct isometries relating the dual Hamiltonians. Whenever a lattice gauge theory is left invariant under the duality operation, we explore the possibility of promoting the self-duality to an internal symmetry. We argue that this results in a symmetry structure that encodes the 2-representations of a 2-group.

  1 citation

• Quantum parameter estimation with many-body fermionic systems and application to the Hall effect

  Olivier Giraud, Mark-Oliver Goerbig, Daniel Braun

  SciPost Phys. 16, 085 (2024) · published 25 March 2024 | Toggle abstract · pdf

  We calculate the quantum Fisher information for a generic many-body fermionic system in a pure state depending on a parameter. We discuss the situations where the parameter is imprinted in the basis states, in the state coefficients, or both. In the case where the parameter dependence of coefficients results from a Hamiltonian evolution, we derive a particularly simple expression for the quantum Fisher information. We apply our findings to the quantum Hall effect, and evaluate the quantum Fisher information associated with the optimal measurement of the magnetic field for a system in the ground state of the effective Hamiltonian. The occupation of electron states with high momentum enforced by the Pauli principle leads to a "super-Heisenberg" scaling of the sensitivity with a power law that depends on the geometry of the sensor.

  1 citation

• Importance of the X-ray edge singularity for the detection of relic neutrinos in the PTOLEMY project

  Zhiyang Tan, Vadim Cheianov

  SciPost Phys. 17, 022 (2024) · published 26 July 2024 | Toggle abstract · pdf

  Direct detection of relic neutrinos in a beta-decay experiment is an ambitious goal that has long been beyond the reach of available technology. One of the most challenging practical difficulties for such an experiment is managing a large amount of radioactive material without compromising the energy resolution required to distinguish useful events from the substantial beta-decay background. The PTOLEMY project offers an innovative solution to this problem by depositing radioactive material on graphene. While this approach is expected to address the main challenge, it introduces new issues due to the proximity of the beta decayers to a solid-state system. In this work, we focus on the effect of the shakeup of the graphene electron system caused by a beta-decay event. We calculate the distortion of the relic neutrino peaks resulting from this shakeup, analyze the impact of the distortion on the visibility of neutrino capture events, and discuss potential technological solutions to enhance the visibility of these events.

  1 citation

• Next-to-leading power SCET in Higgs amplitudes induced by light quarks

  Xing Wang

  SciPost Phys. Proc. 7, 040 (2022) · published 22 June 2022 | Toggle abstract · pdf

  In this article, we report how to use the "plus-type" subtraction scheme to deal with endpoint divergences in $h\rightarrow\gamma\gamma$ or $gg\rightarrow h$ amplitudes induced by light quark loop, which can be formulated by next-to-leading power (NLP) SCET. This subtraction is ensured by two re-factorization conditions, which have been proven to all orders in $\alpha_s$. Based on these conditions, cutoffs emerge naturally after some re-arrangements to handle endpoint divergences and renormalization is compatible with that. Our formalism can analytically reproduce three-loop amplitudes up to $\ln^3(-M_h^2/m_b^2-i0)$ and resum to next-to-leading logarithm and beyond.

  1 citation

• Measurement of 3He analyzing power for p-3He scattering using the polarized 3He target

  A. Watanabe, S. Nakai, K. Sekiguchi, T. Akieda, D. Etoh, M. Inoue, Y. Inoue, K. Kawahara, H. Kon, K. Miki, T. Mukai, D. Sakai, S. Shibuya, Y. Shiokawa, T. Taguchi, H. Umetsu, Y. Utsuki, Y. Wada, M. Watanabe, M. Itoh, T. Ino, T. Wakui, K. Hatanaka, H. Kanda, H. J. Ong, D. T. Tran, S. Goto, Y. Hirai, D. Inomoto, H. Kasahara, S. Mitsumoto, H. Oshiro, T. Wakasa, Y. Maeda, K. Nonaka, H. Sakai, T. Uesaka

  SciPost Phys. Proc. 3, 020 (2020) · published 25 February 2020 | Toggle abstract · pdf

  Proton–3He scattering is one of the good probes to study the T = 3/2 channel of three– nucleon forces. We have measured 3He analyzing powers for p−3He elastic scattering with the polarized 3He target at 70 and 100 MeV. In the conference the data were com- pared with the theoretical predictions based on the modern nucleon–nucleon potentials. Large discrepancies were found between the data and the calculations at the angles where the 3He analyzing power takes the minimum and maximum values.

  1 citation

• Attention to the strengths of physical interactions: Transformer and graph-based event classification for particle physics experiments

  Luc Builtjes, Sascha Caron, Polina Moskvitina, Clara Nellist, Roberto Ruiz de Austri, Rob Verheyen, Zhongyi Zhang

  SciPost Phys. 19, 028 (2025) · published 28 July 2025 | Toggle abstract · pdf

  A major task in particle physics is the measurement of rare signal processes. Even modest improvements in background rejection, at a fixed signal efficiency, can significantly enhance the measurement sensitivity. Building on prior research by others that incorporated physical symmetries into neural networks, this work extends those ideas to include additional physics-motivated features. Specifically, we introduce energy-dependent particle interaction strengths, derived from leading-order SM predictions, into modern deep learning architectures, including Transformer Architectures (Particle Transformer), and Graph Neural Networks (Particle Net). These interaction strengths, represented as the SM interaction matrix, are incorporated into the attention matrix (transformers) and edges (graphs). Our results in event classification show that the integration of all physics-motivated features improves background rejection by $10\%-40\%$ over baseline models, with an additional gain of up to $9\%$ due to the SM interaction matrix. This study also provides one of the broadest comparisons of event classifiers to date, demonstrating how various architectures perform across this task. A simplified statistical analysis demonstrates that these enhanced architectures yield significant improvements in signal significance compared to a graph network baseline.

  1 citation

• Comments on the negative grade KdV hierarchy

  Y. F. Adans, Jose F. Gomes, G. V. Lobo, A. H. Zimerman

  SciPost Phys. Proc. 14, 014 (2023) · published 23 November 2023 | Toggle abstract · pdf

  The construction of negative grade KdV hierarchy is proposed in terms of a Miura-gauge transformation. Such gauge transformation is employed within the zero curvature representation and maps the Lax operator of the mKdV into its couterpart within the KdV setting. Each odd negative KdV flow is obtained from an odd and its subsequent even negative mKdV flows. The negative KdV flows are shown to inherit the two different vacua structure that characterizes the associated mKdV flows.

  1 citation

• Parallel assembly of neutral atom arrays with an SLM using linear phase interpolation

  Ivo H. A. Knottnerus, Yu Chih Tseng (曾于誌), Alexander Urech, Robert J. C. Spreeuw, Florian Schreck

  SciPost Phys. 19, 118 (2025) · published 31 October 2025 | Toggle abstract · pdf

  We present fast parallel rearrangement of single atoms in optical tweezers into arbitrary geometries by updating holograms displayed by an ultra fast spatial light modulator. Using linear interpolation of the tweezer position and the optical phase between the start and end arrays, we can calculate and display holograms every few ms, limited by technology. To show the versatility of our method, we sort the same atomic sample into multiple geometries with success probabilities of $0.996(2)$ per rearrangement cycle. This makes the method a useful tool for rearranging large atom arrays for quantum computation and quantum simulation.

  1 citation

• LiHoF4 as a spin-half non-standard quantum Ising system

  Tomer Dollberg, Moshe Schechter

  SciPost Phys. 17, 028 (2024) · published 31 July 2024 | Toggle abstract · pdf

  LiHoF$_{4}$ is a magnetic material known for its Ising-type anisotropy, making it a model system for studying quantum magnetism. However, the theoretical description of LiHoF$_{4}$ using the quantum Ising model has shown discrepancies in its phase diagram, particularly in the regime dominated by thermal fluctuations. In this study, we investigate the role of off-diagonal dipolar terms in LiHoF$_{4}$, previously neglected, in determining its properties. We analytically derive the low-energy effective Hamiltonian of LiHoF$_{4}$, including the off-diagonal dipolar terms perturbatively, both in the absence and presence of a transverse field. Our results encompass the full \boldmath{$B_{x}-T$} phase diagram, confirming the significance of the off-diagonal dipolar terms in reducing the zero-field critical temperature and determining the critical temperature's dependence on the transverse field. We also highlight the sensitivity of this mechanism to the crystal structure by comparing our calculations with the Fe$_{8}$ system.

  1 citation

• Lecture notes on large deviations in non-equilibrium diffusive systems

  Bernard Derrida

  SciPost Phys. Lect. Notes 106 (2025) · published 29 October 2025 | Toggle abstract · pdf

  These notes are a written version of lectures given in the 2024 Les Houches Summer School on Large deviations and applications. They are are based on a series of works published over the last 25 years on steady properties of non-equilibrium systems in contact with several heat baths at different temperatures or several reservoirs of particles at different densities. After recalling some classical tools to study non-equilibrium steady states, such as the use of tilted matrices, the Fluctuation theorem, the determination of transport coefficients, the Einstein relations or fluctuating hydrodynamics, they describe some of the basic ideas of the macroscopic fluctuation theory allowing to determine the large deviation functions of the density and of the current of diffusive systems.

  1 citation