Publications

Order by: publication date number of citations

• Updated results on the cosmic ray energy spectrum and composition from the GRAPES-3 experiment

  F. Varsi, S. Ahmad, M. Chakraborty, A. Chandra, S. R. Dugad, U. D. Goswami, S. K. Gupta, B. Hariharan, Y. Hayashi, P. Jagadeesan, A. Jain , P. Jain, S. Kawakami, H. Kojima, S. Mahapatra, P. K. Mohanty, R. Moharana, Y. Muraki, P. K. Nayak, T. Nonaka, A. Oshima, B. P. Pant, D. Pattanaik, G. Pradhan, M. Rameez, K. Ramesh, L. V. Reddy, R. Sahoo, R. Scaria, S. Shibata, K. Tanaka, M. Zuberi

  SciPost Phys. Proc. 13, 031 (2023) · published 29 September 2023 | Toggle abstract · pdf

  Here, we present the updated results on the cosmic ray energy spectrum and composition analysis from the GRAPES-3 experiment over the energy range of 50 TeV to 1000 TeV since ICRC 2021. The simulation of cosmic ray showers was performed using the post-LHC high energy hadronic interaction model QGSJetII-04 and low energy hadronic model FLUKA. A detailed GEANT4 simulation of the GRAPES-3 muon telescope was performed. The composition was obtained by fitting simulated muon multiplicity distributions for proton, helium, nitrogen, aluminium, and iron primaries to the observed data. The energy spectrum connects to the direct measurements with a fairly good agreement in flux.

• Inverted pendulum driven by a horizontal random force: statistics of the never-falling trajectory and supersymmetry

  Nikolai A. Stepanov, Mikhail A. Skvortsov

  SciPost Phys. 13, 021 (2022) · published 16 August 2022 | Toggle abstract · pdf

  We study stochastic dynamics of an inverted pendulum subject to a random force in the horizontal direction (Whitney's problem). Considered on the entire time axis, the problem admits a unique solution that always remains in the upper half plane. We formulate the problem of statistical description of this never-falling trajectory and solve it by a field-theoretical technique assuming a white-noise driving. In our approach based on the supersymmetric formalism of Parisi and Sourlas, statistic properties of the never-falling trajectory are expressed in terms of the zero mode of the corresponding transfer-matrix Hamiltonian. The emerging mathematical structure is similar to that of the Fokker-Planck equation, which however is written for the "square root" of the probability distribution function. Our results for the statistics of the non-falling trajectory are in perfect agreement with direct numerical simulations of the stochastic pendulum equation. In the limit of strong driving (no gravitation), we obtain an exact analytical solution for the instantaneous joint probability distribution function of the pendulum's angle and its velocity.

• Generalisation of affine Lie algebras on compact real manifolds

  Rutwig Campoamor-Stursberg, Marc de Montigny, Michel Rausch de Traubenberg

  SciPost Phys. Proc. 14, 022 (2023) · published 23 November 2023 | Toggle abstract · pdf

  We report on recent work concerning a new type of generalised Kac-Moody algebras based on the spaces of differentiable mappings from compact manifolds or homogeneous spaces onto compact Lie groups.

• Probabilistic deconstruction of a theory of gravity, part II: Curved space

  Sunok Josephine Suh

  SciPost Phys. 16, 012 (2024) · published 17 January 2024 | Toggle abstract · pdf

  We propose that the underlying context of holographic duality and the Ryu-Takayanagi formula is that the volume measure of spacetime is a probability measure constrained by quantum dynamics. We define quantum stochastic processes using joint quantum distributions which are realized in a quantum system as expectation values of products of projectors. In anti-de Sitter JT gravity, we show that Einstein's equations arise from the evolution of probability under the quantum stochastic process induced by the boundary, with the area of compactified space in the gravitational theory identified as a probability density evolving under the quantum process. Extrapolating these and related results in flat JT gravity found in [SciPost Phys. 15, 174 (2023)], we conjecture that general relativity arises in the semi-classical limit of the evolution of probability with respect to quantum stochastic processes.

• Hilbert space structure and classical limit of the low energy sector of U(N) quantum Hall ferromagnets

  Manuel Calixto, Alberto Mayorgas, Julio Guerrero

  SciPost Phys. Proc. 14, 021 (2023) · published 23 November 2023 | Toggle abstract · pdf

  Using the Lieb–Mattis ordering theorem of electronic energy levels, we identify and construct the Hilbert space of the low energy sector of U(N) quantum Hall/Heisenberg ferromagnets at filling factor M for L Landau/lattice sites. The carrier Hilbert space of irreducible representations of U(N) is described by rectangular Young tableaux of M rows and L columns, and associated with Grassmannian phase spaces U(N)/U(M)×U(N-M). Replacing U(N)-spin operators by their expectation values in a Grassmannian coherent state allows for a semi-classical treatment of the low energy U(N)-spin-wave coherent excitations (skyrmions) of U(N) quantum Hall ferromagnets in terms of Grasmannian nonlinear sigma models.

• Remembering David J. Rowe

  John L. Wood, Piet Van Isacker

  SciPost Phys. Proc. 14, 013 (2023) · published 23 November 2023 | Toggle abstract · pdf

  David Rowe was a highly respected theoretical physicist who made seminal contributions that improved our understanding of the atomic nucleus, in particular of the collective behaviour of its constituent nucleons - results he often obtained with the use of sophisticated group-theoretical methods. He will also be remembered as the (co-)author of monographs on nuclear physics, written with the scientific rigour that was characteristic of his research.

• Coherent photoproduction of $J/\psi$ in nucleus-nucleus collisions \\in the color dipole approach- an update

  Agnieszka Łuszczak, Wolfgang Schäfer

  SciPost Phys. Proc. 8, 109 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We discuss the role of $c \bar c g$-Fock states in the diffractive photoproduction of $J/\psi$-mesons. We build on our earlier description of the process in the color-dipole approach, where we took into account the rescattering of $c \bar c$ pairs using a Glauber-Gribov form of the dipole-nucleus amplitude. We compare the results of our calculations to recent data on the photoproduction of $J/\psi$ by the ALICE and LHCb collaborations.

• Tchavdar Dimitrov Palev - In memoriam

  N. I. Stoilova

  SciPost Phys. Proc. 14, 011 (2023) · published 23 November 2023 | Toggle abstract · pdf

  Tchavdar Dimitrov Palev – In memoriam

• SO(1,3) Yang-Mills solutions on Minkowski space via cosets

  Kaushlendra Kumar

  SciPost Phys. Proc. 14, 033 (2023) · published 24 November 2023 | Toggle abstract · pdf

  We present a novel family of Yang-Mills solutions, with gauge group SO(1,3), on Minkowski space that are geometrically distinguished into two classes, viz. interior and exterior of the lightcone. We achieve this by foliating the former with SO(1,3)/SO(3) cosets and the latter with SO(1,3)/SO(1,2) cosets and analytically solving the Yang-Mills equation of an SO(1,3)-invariant gauge field. The resulting fields and their stress-energy tensor, when translated to the Minkowski space, diverge at the lightcone, but we demonstrate how this stress-energy tensor could be regularised due to its unique algebraic structure.

• Seven-dimensional super Yang-Mills at negative coupling

  Joseph A. Minahan, Usman Naseer, Charles Thull

  SciPost Phys. 14, 028 (2023) · published 6 March 2023 | Toggle abstract · pdf

  We consider the partition function for Euclidean $SU(N)$ super Yang-Mills on a squashed seven-sphere. We show that the localization locus of the partition function has instanton membrane solutions wrapping the six ``fixed" three-spheres on the $\mathbb{S}^7$. The ADHM variables of these instantons are fields living on the membrane world volume. We compute their contribution by localizing the resulting three-dimensional supersymmetric field theory. In the round-sphere limit the individual instanton contributions are singular, but the singularities cancel when adding the contributions of all six three-spheres. The full partition function on the ${\mathbb S}^7$ is well-defined even when the square of the effective Yang-Mills coupling is negative. We show for an $SU(2)$ gauge theory in this regime that the bare negative tension of the instanton membranes is canceled off by contributions from the instanton partition function, indicating the existence of tensionless membranes. We provide evidence that this phase is distinct from the usual weakly coupled super Yang-Mills and, in fact, is gravitational.