Publications

Order by: publication date number of citations

• Highlights from the Telescope Array Experiment

  Hiroyuki Sagawa for the Telescope Array Collaboration

  SciPost Phys. Proc. 13, 041 (2023) · published 29 September 2023 | Toggle abstract · pdf

  The Telescope Array (TA) is the largest hybrid cosmic ray detector in the Northern Hemisphere, which observes primary particles in the energy range from 2 PeV to 100 EeV. The main TA detector consists of 507 plastic scintillation counters on a 1.2-km spacing square grid and fluorescence detectors at three stations overlooking the sky above the surface detector array. The TA Low energy Extension (TALE) detector, which consists of ten fluorescence telescopes, and 80 infill surface detectors with 400m and 600 m spacing, has continued to provide stable observations since its construction completion in 2018. The TAx4, a plan to quadruple the detection area of TA is also ongoing. About half of the planned surface detectors have been deployed, and the current TAx4 continues to operate stably as a hybrid detector. I review the present status of the TA experiment and the recent results on the cosmic-ray anisotropy, mass composition and energy spectrum.

  1 citation

• Time-dependent variational Monte Carlo study of the dynamic response of bosons in an optical lattice

  Mathias Gartner, Ferran Mazzanti, Robert E. Zillich

  SciPost Phys. 13, 025 (2022) · published 18 August 2022 | Toggle abstract · pdf

  We study the dynamics of a one-dimensional Bose gas at unit filling in both shallow and deep optical lattices and obtain the dynamic structure factor ${S(k,\omega)}$ by monitoring the linear response to a weak probe pulse. We introduce a new procedure, based on the time-dependent variational Monte Carlo method (tVMC), which allows to evolve the system in real time, using as a variational model a Jastrow-Feenberg wave function that includes pair correlations. Comparison with exact diagonalization results of ${S(k,\omega)}$ obtained on a lattice in the Bose-Hubbard limit shows good agreement of the dispersion relation for sufficiently deep optical lattices, while for shallow lattices we observe the influence of higher Bloch bands. We also investigate non-linear response to strong pulses. From the power spectrum of the density fluctuations we obtain the excitation spectrum, albeit broadened, by higher harmonic generation after a strong pulse with a single low wave number. As a remarkable feature of our simulations we furthermore demonstrate that the full excitation spectrum can be retrieved from the power spectrum of the density fluctuations due to the stochastic noise inherent in any Monte Carlo method, without applying an actual perturbation.

  1 citation

• divERGe implements various Exact Renormalization Group examples

  Jonas B. Profe, Dante M. Kennes, Lennart Klebl

  SciPost Phys. Codebases 26 (2024) · published 8 February 2024 | Toggle abstract · pdf

  We present divERGe, an open source, high-performance C/C++/Python library for functional renormalization group (FRG) calculations on lattice fermions. The versatile model interface is tailored to real materials applications and seamlessly integrates with existing, standard tools from the ab-initio community. The code fully supports multi-site, multi-orbital, and non-SU(2) models in all of the three included FRG variants: TU$^2$FRG, N-patch FRG, and grid FRG. With this, the divERGe library paves the way for widespread application of FRG as a tool in the study of competing orders in quantum materials.

  1 citation

• Proton penetration efficiency over a high altitude observatory in Mexico

  S. Miyake, T. Koi, Y. Muraki, Y. Matsubara, S. Masuda, P. Miranda, T. Naito, E. Ortiz, A. Oshima, T. Sakai, T. Sako, S. Shibata, H. Takamaru, M. Tokumaru, J. F. Valdés-Galicia

  SciPost Phys. Proc. 13, 001 (2023) · published 28 September 2023 | Toggle abstract · pdf

  In association with a large solar flare on November 7, 2004, the solar neutron detectors located at Mt. Chacaltaya (5,250 m) in Bolivia and Mt. Sierra Negra (4,600 m) in Mexico recorded very interesting events. In order to explain these events, we have performed a calculation solving the equation of motion of anti-protons inside the magnetosphere. Based on these results, the Mt. Chacaltaya event may be explained by the detection of solar neutrons, while the Mt. Sierra Negra event may be explained by the first detection of very high energy solar neutron decay protons (SNDPs) around 6 GeV.

  1 citation

• Traveling discontinuity at the quantum butterfly front

  Camille Aron, Éric Brunet, Aditi Mitra

  SciPost Phys. 15, 042 (2023) · published 2 August 2023 | Toggle abstract · pdf

  We formulate a kinetic theory of quantum information scrambling in the context of a paradigmatic model of interacting electrons in the vicinity of a superconducting phase transition. We carefully derive a set of coupled partial differential equations that effectively govern the dynamics of information spreading in generic dimensions. Their solutions show that scrambling propagates at the maximal speed set by the Fermi velocity. At early times, we find exponential growth at a rate set by the inelastic scattering. At late times, we find that scrambling is governed by shock-wave dynamics with traveling waves exhibiting a discontinuity at the boundary of the light cone. Notably, we find perfectly causal dynamics where the solutions do not spill outside of the light cone.

  1 citation

• Non-standard neutrino spectra from annihilating neutralino dark matter

  Melissa van Beekveld, Wim Beenakker, Sascha Caron, Jochem Kip, Roberto Ruiz de Austri, Zhongyi Zhang

  SciPost Phys. Core 6, 006 (2023) · published 7 February 2023 | Toggle abstract · pdf

  Neutrino telescope experiments are rapidly becoming more competitive in indirect detection searches for dark matter. Neutrino signals arising from dark matter annihilations are typically assumed to originate from the hadronisation and decay of Standard Model particles. Here we showcase a supersymmetric model, the BLSSMIS, that can simultaneously obey current experimental limits while still providing a potentially observable non-standard neutrino spectrum from dark matter annihilation.

  1 citation

• Central exclusive production of axial-vector f1 mesons in proton-proton collisions within the tensor-pomeron approach

  Piotr Lebiedowicz

  SciPost Phys. Proc. 6, 010 (2022) · published 31 May 2022 | Toggle abstract · pdf

  We discuss the central exclusive production of $f_{1}$ mesons in proton-proton collisions. The diffractive pomeron-pomeron fusion process within the tensor-pomeron approach is considered. Two ways to construct the pomeron-pomeron-$f_{1}$ coupling are discussed. The theoretical calculation of coupling constants is a challenging problem of nonperturbative QCD. We adjust the parameters of the model to the WA102 experimental data. The total cross section and differential distributions are presented. Predictions for LHC experiments are given. Detailed analysis of the distributions in $\phi_{pp}$ the azimuthal angle between the transverse momenta of the outgoing protons can help to check different models and to study real pattern of the absorption effects.

  1 citation

• An exact method for bosonizing the Fermi surface in arbitrary dimensions

  Takamori Park, Leon Balents

  SciPost Phys. 16, 069 (2024) · published 8 March 2024 | Toggle abstract · pdf

  Inspired by the recent work by Delacretaz et. al. [Phys. Rev. Res. 4, 033131 (2022)], we rigorously derive an exact and simple method to bosonize a non-interacting fermionic system with a Fermi surface starting from a microscopic Hamiltonian. In the long-wavelength limit, we show that the derived bosonized action is exactly equivalent to the action obtained by Delacretaz et. al. In addition, we propose diagrammatic rules to evaluate correlation functions using our bosonized theory and demonstrate these rules by calculating the three- and four-point density correlation functions. We also consider a general density-density interaction and show that the simplest approximation in our bosonic theory is identical to RPA results.

  1 citation

• Probing black hole microstate evolution with networks and random walks

  Anthony M. Charles, Daniel R. Mayerson

  SciPost Phys. 8, 077 (2020) · published 14 May 2020 | Toggle abstract · pdf

  We model black hole microstates and quantum tunneling transitions between them with networks and simulate their time evolution using well-established tools in network theory. In particular, we consider two models based on Bena-Warner three-charge multi-centered microstates and one model based on the D1-D5 system; we use network theory methods to determine how many centers (or D1-D5 string strands) we expect to see in a typical late-time state. We find three distinct possible phases in parameter space for the late-time behaviour of these networks, which we call ergodic, trapped, and amplified, depending on the relative importance and connectedness of microstates. We analyze in detail how these different phases of late-time behavior are related to the underlying physics of the black hole microstates. Our results indicate that the expected properties of microstates at late times cannot always be determined simply by entropic arguments; typicality is instead a highly non-trivial, emergent property of the full Hilbert space of microstates.

  1 citation

• Three-body correlations in mesonic-atom-like systems

  Hajime Moriya, Wataru Horiuchi, Jean-Marc Richard

  SciPost Phys. Proc. 3, 051 (2020) · published 27 February 2020 | Toggle abstract · pdf

  Three-body correlations in three-body exotic atoms are studied with simple models that consist of three bosons interacting through a superposition of long- and short-range potentials. We discuss the correlations among particles by comparing the energy shifts given by precise three-body calculations and by the Deser-Trueman formula, in which the long- and short-range contributions are factorized. By varying the coupling of the short-range potential, we evaluate the ranges of the strength where the two-body correlations dominate and where the three-body correlations cannot be neglected.

  1 citation