Publications

Order by: publication date number of citations

• Parametrization and thermodynamic scaling of pair correlation functions for the fractional quantum Hall effect

  Jørgen Fulsebakke, Mikael Fremling, Niall Moran, Joost K. Slingerland

  SciPost Phys. 14, 149 (2023) · published 9 June 2023 | Toggle abstract · pdf

  The calculation of pair correlations and density profiles of quasiholes are routine steps in the study of proposed fractional quantum Hall states. Nevertheless, the field has not adopted a standard way to present the results of such calculations in an easily reproducible form. We develop a polynomial expansion that allows for easy quantitative comparison between different candidate wavefunctions, as well as reliable scaling of correlation and quasihole profiles to the thermodynamic limit. We start from the well-known expansion introduced by Girvin [PRB, 30 (1984)] (see also [Girvin, MacDonald and Platzman, PRB, 33 (1986)]), which is physically appealing but, as we demonstrate, numerically unstable. We orthogonalize their basis set to obtain a new basis of modified Jacobi polynomials, whose coefficients can be stably calculated. We then apply our expansion to extract pair correlation expansion coefficients and quasihole profiles in the thermodynamic limit for a wide range of fractional quantum Hall wavefunctions. These include the Laughlin series, composite fermion states with both reverse and direct flux attachment, the Moore-Read Pfaffian state, and BS hierarchy states. The expansion procedure works for both abelian and non-abelian quasiholes, even when the density at the core is not zero. We find that the expansion coefficients for all quantum Hall states considered can be fit remarkably well using a cosine oscillation with exponentially decaying amplitude. The frequency and the decay length are related in an intuitive, but not elementary way to the filling fraction. Different states at the same filling fraction can have distinct values for these parameters. Finally, we also use our scaled correlation functions to calculate estimates for the magneto-roton gaps of the various states.

  2 citations

• Recent results on hyperon pair production and nucleon time-like form factors at BESIII

  Alessio Mangoni

  SciPost Phys. Proc. 10, 021 (2022) · published 10 August 2022 | Toggle abstract · pdf

  The BESIII experiment, based on the BEPCII collider at IHEP in Beijing, China, is capable of measuring nucleon form factors with unprecedented precision. We report recent results achieved by the BESIII collaboration concerning the nucleon time-like form factors and the hyperon pair production. More in detail we outline the results obtained by the study of the process $e^+e^- \to p \overline p$, using both the scan-energy and initial-state radiation techniques, those of the process $e^+e^- \to n \overline n$, and the study of the $\Sigma$ polarization regarding the process $e^+e^- \to J/\psi \to \Sigma^+\overline \Sigma{}^-$.

  2 citations

• Extracting the symmetries of nonequilibrium quantum many-body systems

  Aleksandr N. Mikheev, Viktoria Noel, Ido Siovitz, Helmut Strobel, Markus K. Oberthaler, Jürgen Berges

  SciPost Phys. 18, 044 (2025) · published 4 February 2025 | Toggle abstract · pdf

  Symmetries play a pivotal role in our understanding of the properties of quantum many-body systems. While there are theorems and a well-established toolbox for systems in thermal equilibrium, much less is known about the role of symmetries and their connection to dynamics out of equilibrium. This arises due to the direct link between a system's thermal state and its Hamiltonian, which is generally not the case for nonequilibrium dynamics. Here we present a pathway to identify the effective symmetries and to extract them from data in nonequilibrium quantum many-body systems. Our approach is based on exact relations between correlation functions involving different numbers of spatial points, which can be viewed as nonequilibrium versions of (equal-time) Ward identities encoding the symmetries of the system. We derive symmetry witnesses, which are particularly suitable for the analysis of measured or simulated data at different snapshots in time. To demonstrate the potential of the approach, we apply our method to numerical and experimental data for a spinor Bose gas. We investigate the important question of a dynamical restoration of an explicitly broken symmetry of the Hamiltonian by the initial state. Remarkably, it is found that effective symmetry restoration can occur long before the system equilibrates. We also use the approach to define and identify spontaneous symmetry breaking far from equilibrium, which is of great relevance for applications to nonequilibrium phase transitions. Our work opens new avenues for the classification and analysis of quantum as well as classical many-body dynamics in a large variety of systems, ranging from ultracold quantum gases to cosmology.

  2 citations

• Correlation between antiferromagnetic and charge-density-wave order in UPt$_{2}$Si$_{2}$ studied by resonant X-Ray scattering

  Fusako Kon, Chihiro Tabata, Kodai Miura, Ruo Hibino, Hiroyuki Hidaka, Tatsuya Yanagisawa, Hironori Nakao, Hiroshi Amitsuka

  SciPost Phys. Proc. 11, 011 (2023) · published 5 June 2023 | Toggle abstract · pdf

  Relationship between antiferromagnetic order with Néel temperature of 35 K and charge-density-wave (CDW) order below 320 K of UPt$_2$Si$_2$ has been investigated by resonant X-ray scattering measurements. We have found that a resonant scattering signal develops below the Néel temperature at the ${ M}_{ 4}$ absorption edge of uranium with a propagation vector of the CDW order ${ q}_{ CDW} \sim$ (0.42, 0, 0). The experimental results reveal that the magnetic structure of UPt$_2$Si$_2$ is modulated by the CDW ordering.

  2 citations

• Intermittency Analysis of Toy Monte Carlo Events

  Sheetal Sharma, Ramni Gupta

  SciPost Phys. Proc. 10, 024 (2022) · published 11 August 2022 | Toggle abstract · pdf

  Event-by-event intermittency analysis of Toy Monte Carlo events is performed in the scenario of high multiplicity events as is the case at recent colliders RHIC and LHC for AA collisions. A power law behaviour of Normalized Factorial Moments (NFM), $F_{q}$ as function of number of bins ($M$) known as intermittency, is a signature of self-similar fluctuations. Dependence of NFM on the detector efficiencies and on the presence of fluctuations have been studied. Results presented here provide a baseline to the experimental results and clarity on the application of efficiency corrections to the experimental data.

  2 citations

• Entropy driven inductive response of topological insulators

  A. Mert Bozkurt, Sofie Kölling, Alexander Brinkman, İnanç Adagideli

  SciPost Phys. Core 8, 023 (2025) · published 18 February 2025 | Toggle abstract · pdf

  3D topological insulators are characterized by an insulating bulk and extended surface states exhibiting a helical spin texture. In this work, we investigate the hyperfine interaction between the spin-charge coupled transport of electrons and the nuclear spins in these surface states. Previous work has predicted that in the quantum spin Hall insulator phase, work can be extracted from a bath of polarized nuclear spins as a resource. We employ nonequilibrium Green's function analysis to show that a similar effect exists on the surface of a 3D topological insulator, albeit rescaled by the ratio between electronic mean free path and device length. The induced current due to thermal relaxation of polarized nuclear spins has an inductive nature. We emphasize the inductive response by rewriting the current-voltage relation in harmonic response as a lumped element model containing two parallel resistors and an inductor. In a low-frequency analysis, a universal inductance value emerges that is only dependent on the device's aspect ratio. This scaling offers a means of miniaturizing inductive circuit elements. An efficiency estimate follows from comparing the spin-flip induced current to the Ohmic contribution. The inductive effect is most prominent in topological insulators which have a large number of spinful nuclei per coherent segment, of which the volume is given by the mean free path length, Fermi wavelength and penetration depth of the surface state.

  2 citations

• The NFLikelihood: An unsupervised DNNLikelihood from normalizing flows

  Humberto Reyes-González, Riccardo Torre

  SciPost Phys. Core 7, 048 (2024) · published 31 July 2024 | Toggle abstract · pdf

  We propose the NFLikelihood, an unsupervised version, based on Normalizing Flows, of the DNNLikelihood proposed in [Eur. Phys. J. C 80, 664 (2020)]. We show, through realistic examples, how Autoregressive Flows, based on affine and rational quadratic spline bijectors, are able to learn complicated high-dimensional Likelihoods arising in High Energy Physics (HEP) analyses. We focus on a toy LHC analysis example already considered in the literature and on two Effective Field Theory fits of flavor and electroweak observables, whose samples have been obtained through the HEPFit code. We discuss advantages and disadvantages of the unsupervised approach with respect to the supervised one and discuss a possible interplay between the two.

  2 citations

• LHC EFT WG note: Basis for anomalous quartic gauge couplings

  Gauthier Durieux, Grant N. Remmen, Nicholas L. Rodd, Oscar J. P. Éboli, Maria C. Gonzalez-Garcia, Dan Kondo, Hitoshi Murayama, Risshin Okabe

  SciPost Phys. Comm. Rep. 6 (2025) · published 28 February 2025 | Toggle abstract · pdf

  In this note, we give a definitive basis for the dimension-eight operators leading to quartic—but no cubic—interactions among electroweak gauge bosons. These are often called anomalous quartic gauge couplings, or aQGCs. We distinguish in particular the CP-even ones from their CP-odd counterparts.

  2 citations

• Data reduction for low energy nuclear physics experiments using data frames

  Caleb Marshall

  SciPost Phys. Codebases 37 (2024) · published 6 November 2024 | Toggle abstract · pdf

  Low energy nuclear physics experiments are transitioning towards fully digital data acquisition systems. Realizing the gains in flexibility afforded by these systems relies on equally flexible data reduction techniques. In this paper, methods utilizing data frames and in-memory techniques to work with data, including data from self-triggering, digital data acquisition systems, are discussed within the context of a Python package, sauce. It is shown that data frame operations can encompass common analysis needs and allow interactive data analysis. Two event building techniques, dubbed referenced and referenceless event building, are shown to provide a means to transform raw list mode data into correlated multi-detector events. These techniques are demonstrated in the analysis of two example data sets.

  2 citations

• Cosmological infrared subtractions & infrared-safe computables

  Paolo Benincasa, Francisco Vazão

  SciPost Phys. 18, 176 (2025) · published 4 June 2025 | Toggle abstract · pdf

  Cosmological observables in perturbation theory turn out to be plagued with infrared divergences, which represents both a conceptual and computational challenge. In this paper we present a proof of concept for a systematic procedure to remove these divergences in a large class of scalar cosmological integrals and consistently define an infrared safe computable in perturbation theory. We provide diagrammatic rules which are based on the nestohedra underlying the asymptotic structure of such integrals.

  2 citations