Publications

Order by: publication date number of citations

• Bayesian active search on parameter space: A 95 GeV spin-0 resonance in the ($B-L$)SSM

  Mauricio A. Diaz, Giorgio Cerro, Srinandan Dasmahapatra, Stefano Moretti

  SciPost Phys. Core 8, 068 (2025) · published 10 October 2025 | Toggle abstract · pdf

  In the attempt to explain possible data anomalies from collider experiments in terms of New Physics (NP) models, computationally expensive scans over their parameter spaces are typically required in order to match theoretical predictions to experimental observations. Under the assumption that anomalies seen at a mass of about 95 GeV by the Large Electron-Positron (LEP) and Large Hadron Collider (LHC) experiments correspond to a NP signal, which we attempt to interpret as a spin-0 resonance in the $(B-L)$ Supersymmetric Standard Model ($(B-L)$SSM), chosen as an illustrative example, we introduce a novel Machine Learning (ML) approach based on a multi-objective active search method, called b-CASTOR, able to achieve high sample efficiency and diversity, due to the use of probabilistic surrogate models and a volume based search policy, outperforming competing algorithms, such as those based on Markov-Chain Monte Carlo (MCMC) methods.

  1 citation

• Energy loss due to defect creation in solid state detectors

  Matti Heikinheimo, Sebastian Sassi, Kimmo Tuominen, Kai Nordlund, Nader Mirabolfathi

  SciPost Phys. Proc. 12, 010 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The threshold displacement energy in solid state detector materials varies from several eV to $\lesssim$ 100 eV. If a stable or long lived defect is created as a result of a nuclear recoil event, some part of the recoil energy is stored in the deformed lattice and is therefore not observable in a phonon detector. Thus, an accurate model of this effect is necessary for precise calibration of the recoil energy measurement in low threshold phonon detectors. Furthermore, the sharpness of the defect creation threshold varies between materials. For a hard material such as diamond, the sharp threshold will cause a sudden onset of the energy loss effect, resulting in a prominent peak in the observed recoil spectrum just below the threshold displacement energy. We describe how this effect can be used to discriminate between nuclear and electron recoils using just the measured recoil spectrum.

  1 citation

• Estimating time in quantum chaotic systems and black holes

  Haifeng Tang, Shreya Vardhan, Jinzhao Wang

  SciPost Phys. 19, 095 (2025) · published 13 October 2025 | Toggle abstract · pdf

  We characterize new universal features of the dynamics of chaotic quantum many-body systems, by considering a hypothetical task of "time estimation". Most macroscopic observables in a chaotic system equilibrate to nearly constant late-time values. Intuitively, it should become increasingly difficult to estimate the precise value of time by making measurements on the state. We use a quantity called the Fisher information from quantum metrology to quantify the minimum uncertainty in estimating time. Due to unitarity, the uncertainty in the time estimate does not grow with time if we have access to optimal measurements on the full system. Restricting the measurements to act on a small subsystem or to have low computational complexity leads to results expected from equilibration, where the time uncertainty becomes large at late times. With optimal measurements on a subsystem larger than half of the system, we regain the ability to estimate the time very precisely, even at late times. Hawking's calculation for the reduced density matrix of the black hole radiation in semiclassical gravity contradicts our general predictions for unitary quantum chaotic systems. Hawking's state always has a large uncertainty for attempts to estimate the time using the radiation, whereas our general results imply that the uncertainty should become small after the Page time. This gives a new version of the black hole information loss paradox in terms of the time estimation task. By restricting to simple measurements on the radiation, the time uncertainty becomes large. This indicates from a new perspective that the observations of computationally bounded agents are consistent with the semiclassical effective description of gravity.

  1 citation

• Single-Logarithmic Corrections to Small-$x$ Helicity Evolution

  Yossathorn Tawabutr

  SciPost Phys. Proc. 8, 103 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The small-$x$ quark helicity evolution equations at double-logarithmic order, with the kernel $\sim\alpha_s\ln^2(1/x)$, have been derived previously. In this work, we derive the single-logarithmic corrections to the equations, to order $\alpha_s\ln(1/x)$ of the evolution kernel. The new equations include the effects of the running coupling and the unpolarized small-$x$ evolution, both of which are parametrically significant at single-logarithmic order. The large-$N_c$ and large-$N_c\& N_f$ approximations to the equation are computed. (Here, $N_c$ and $N_f$ are the numbers of quark colors and flavors, respectively.) Their solutions will provide more precise estimates of the quark helicity distribution at small $x$, contributing to the resolution of the proton spin puzzle.

  1 citation

• Codebase release 0.2 for Pychastic

  Radost Waszkiewicz, Maciej Bartczak, Kamil Kolasa, Maciej Lisicki

  SciPost Phys. Codebases 11-r0.2 (2023) · published 3 April 2023 | Toggle abstract · src

  In the last decade, Python-powered physics simulations ecosystem has been growing steadily, allowing greater interoperability, and becoming an important tool in numerical exploration of physical phenomena, particularly in soft matter systems. Driven by the need for fast and precise numerical integration in colloidal dynamics, here we formulate the problem of Brownian Dynamics (BD) in a mathematically consistent formalism of the Itō calculus, and develop a Python package to assist numerical computations. We show that, thanks to the automatic differentiation packages, the classical truncated Taylor-Itō integrators can be implemented without the burden of computing the derivatives of the coefficient functions beforehand. Furthermore, we show how to circumvent the difficulties of BD simulations such as calculations of the divergence of the mobility tensor in the diffusion equation and discontinuous trajectories encountered when working with dynamics on $S^2$ and $SO(3)$. The resulting Python package, Pychastic, is capable of performing BD simulations including hydrodynamic interactions at speeds comparable to dedicated implementations in lower-level programming languages, but with a much simpler end-user interface.

  1 citation

• A benchmark study of dioxygen complexes based on coupled cluster and density functional theory

  Marcel Swart, Marc Reimann

  SciPost Chem. 3, 001 (2024) · published 13 August 2024 | Toggle abstract · pdf

  A set of five compounds containing peroxo, superoxo or bis-μ-oxo moieties has been studied in the gas phase using CCSD(T)/aug-cc-pVQZ, also in combination with Goodson’s continued fraction approach. The corresponding analytical frequencies corroborate assignments of bands from experiments, and thus provide a consistent set of reference data that can be used for benchmarking a range of density functional approximations. A total of 100 density functionals have been checked for the general bond lengths, the specific peroxo/superoxo bond lengths, angles, and vibrational frequencies. There is not one density functional that performs equally well for all of these properties, not even within one class of density functionals.

  1 citation

• Photomultiplier characterisation and its impact on background for SABRE South

  William J. D. Melbourne, Owen Stanley, Phillip Urquijo, Madeleine J. Zurowski

  SciPost Phys. Proc. 12, 061 (2023) · published 5 July 2023 | Toggle abstract · pdf

  SABRE (Sodium iodide with Active Background REjection) South is a NaI(Tl) based dark matter direct detection experiment located at the Stawell Underground Physics Laboratory (SUPL) [J. Phys. Conf. Ser. 2156, 012064 (2021), arXiv:2205.13849]. It is designed to detect an annual modulation of WIMP recoils as an independent replication of the long-standing DAMA/LIBRA modulation signal. SABRE South will have a low energy threshold of 1 keV in the NaI(Tl) crystal detector and a low experimental background. This requires precise characterisation of the photomultipliers used to understand both their sensitivity at low thresholds and their contribution to the background. We report on the photomultiplier characterisation test bench developed for the crystal detector photomultipliers including studies of the single photon response, transit time, and dark noise. A specific focus is on estimating the contribution to the experimental background of coincident photomultiplier noise due to its predominance at low energy and inability to be modelled using traditional MC simulation.

  1 citation

• Testing the mean field theory of scalar field dark matter

  Andrew Eberhardt, Alvaro Zamora, Michael Kopp, Tom Abel

  SciPost Phys. Proc. 12, 058 (2023) · published 5 July 2023 | Toggle abstract · pdf

  Scalar field dark matter offers an interesting alternative to the traditional WIMP dark matter picture. Astrophysical and cosmological simulations are useful to constraining the mass of the dark matter particle in this model. This is particularly true at low mass where the wavelike nature of the dark matter particle manifests on astrophysical scales. These simulations typical use a classical field approximation. In this work, we look at extending these simulations to include quantum corrections. We look into both the ways in which large corrections impact the predictions of scalar field dark matter, and the timescales on which these corrections grow large. Corrections tend to lessen density fluctuations and increase the effect of "quantum pressure". During collapse, these corrections grow exponentially, quantum corrections would become important in about $\sim 30$ dynamical times. This implies that the predictions of classical field simulations may differ from those with quantum corrections for systems with short dynamical times.

  1 citation

• A new Wilson line-based classical action for gluodynamics

  Hiren Kakkad, Piotr Kotko, Anna Stasto

  SciPost Phys. Proc. 7, 011 (2022) · published 20 June 2022 | Toggle abstract · pdf

  We develop a new classical action that in addition to $\mathrm{MHV}$ vertices contains also $\mathrm{N^kMHV}$ vertices, where $1\leq k \leq n-4$ with $n$ the number of external legs. The lowest order vertex is the four-point MHV vertex -- there is no three point vertex and thus the amplitude calculation involves fewer vertices than in the CSW method. The action is obtained by a canonical transformation of the Yang-Mills action in the light-cone gauge, where the field transformations are based on Wilson line functionals.

  1 citation

• Choose your diffusion: Efficient and flexible ways to accelerate the diffusion model in fast high energy physics simulation

  Cheng Jiang, Sitian Qian, Huilin Qu

  SciPost Phys. 18, 195 (2025) · published 18 June 2025 | Toggle abstract · pdf

  The diffusion model has demonstrated promising results in image generation, recently becoming mainstream and representing a notable advancement for many generative modeling tasks. Prior applications of the diffusion model for both fast event and detector simulation in high energy physics have shown exceptional performance, providing a viable solution to generate sufficient statistics within a constrained computational budget in preparation for the High Luminosity LHC. However, many of these applications suffer from slow generation with large sampling steps and face challenges in finding the optimal balance between sample quality and speed. The study focuses on the latest benchmark developments in efficient ODE/SDE-based samplers, schedulers, and fast convergence training techniques. We test on the public CaloChallenge and JetNet datasets with the designs implemented on the existing architecture, the performance of the generated classes surpass previous models, achieving significant speedup via various evaluation metrics.

  1 citation