Publications

Order by: publication date number of citations

• Multiscale pentagon integrals to all orders

  Dhimiter D. Canko, Costas G. Papadopoulos, Nikolaos Syrrakos

  SciPost Phys. Proc. 7, 030 (2022) · published 21 June 2022 | Toggle abstract · pdf

  We present analytical results for one-loop five-point master integrals with up to three off-shell legs. The method of canonical differential equations along with the Simplified Differential Equations approach is employed. All necessary boundary terms are given in closed form, resulting to solutions in terms of Goncharov Polylogarithms of arbitrary weight. Explicit results up to weight six will be presented.

• The quantum Ising chain for beginners

  Glen Bigan Mbeng, Angelo Russomanno, Giuseppe E. Santoro

  SciPost Phys. Lect. Notes 82 (2024) · published 14 June 2024 | Toggle abstract · pdf

  We present here various techniques to work with clean and disordered quantum Ising chains, for the benefit of students and non-experts. Starting from the Jordan-Wigner transformation, which maps spin-1/2 systems into fermionic ones, we review some of the basic approaches to deal with the superconducting correlations that naturally emerge in this context. In particular, we analyze the form of the ground state and excitations of the model, relating them to the symmetry-breaking physics, and illustrate aspects connected to calculating dynamical quantities, thermal averages, correlation functions, and entanglement entropy. A few problems provide simple applications of the techniques.

• Towards higher super-$\sigma$-model categories

  Rafał R. Suszek

  SciPost Phys. Proc. 14, 044 (2023) · published 24 November 2023 | Toggle abstract · pdf

  A simplicial framework for the gerbe-theoretic modelling of supercharged-loop dynamics in the presence of worldsheet defects is discussed whose equivariantisation with respect to global supersymmetries of the bulk theory and subsequent orbit decomposition lead to a natural stratification of and cohomological superselection rules for target-space supergeometry, expected to encode essential information on the quantised 2d field theory. A physically relevant example is analysed in considerable detail.

• 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.

• Mass testing of SiPMs for the CMVD at IICHEP

  Mamta Jangra, Raj Bhupen, Gobinda Majumder, Kiran Gothe, Mandar Saraf, Nandkishor Parmar, Bheesette Satyanarayana, Ravindra R. Shinde, Shobha K. Rao, Suresh S. Upadhya, Vivek M. Datar, Douglas A. Glenzinski, Alan Bross, Anna Pla-Dalmau, Vishnu V. Zutshi, Robert Craig Group, Edmond Craig Dukes

  SciPost Phys. Proc. 13, 025 (2023) · published 29 September 2023 | Toggle abstract · pdf

  A Cosmic Muon Veto Detector (CMVD) is being built around the mini-Iron Calorimeter (mini-ICAL) detector at the transit campus of the India based Neutrino Observatory, Madurai. The CMV detector will be made using extruded plastic scintillators with embedded wavelength shifting (WLS) fibres which propagate re-emitted photons of longer wavelengths to silicon photo-multipliers (SiPMs). The SiPMs detect these scintillation photons, producing electronic signals. The design goal for the cosmic muon veto efficiency of the CMV is $>$99.99% and fake veto rate less than 10$^{-5}$. A testing system was developed, using an LED driver, to measure the noise rate and gain of each SiPM, and thus determine its overvoltage ($V_{ov}$). This paper describes the test results and the analysed characteristics of about 3.5k SiPMs.

• Modified rational six vertex model on the rectangular lattice

  Samuel Belliard, Rodrigo Alves Pimenta, Nikita A. Slavnov

  SciPost Phys. 16, 009 (2024) · published 9 January 2024 | Toggle abstract · pdf

  We consider a rational six vertex model on a rectangular lattice with boundary conditions that generalize the usual domain wall type. We find that the partition function of the inhomogeneous version of this model is given by a modified Izergin determinant. The proofs are based on the quantum inverse scattering method and its representation theory together with elementary linear algebra.

• Generating the electro-weak scale by vector-like quark condensation

  Sophie Klett, Manfred Lindner, Andreas Trautner

  SciPost Phys. 14, 076 (2023) · published 19 April 2023 | Toggle abstract · pdf

  We show that vector-like quarks in the fundamental or higher-dimensional representations of QCD can generate the electro-weak scale in a phenomenologically viable way by chiral symmetry breaking condensates. The thereby generated scales are determined by numerically solving the Dyson-Schwinger equation and these scales are sizable, because they grow with the hard vector-like mass. Communicating such a scale to the Standard Model via a conformally invariant scalar sector can dynamically generate the electro-weak scale without a naturalness problem, because all non-dynamical mass scales are protected by chiral symmetry. We present a minimal setup which requires only a new neutral scalar with mass not too far above the electro-weak scale, as well as vector-like quarks at the (multi-)TeV scale. Both are consistent with current bounds and are attractive for future experimental searches at the LHC and future colliders. Depending on the hypercharge of the vector-like quarks, hadrons made of them are color-neutral bound states which would be interesting Dark Matter candidates.

• Quasiparticle disintegration in fermionic superfluids

  Senne Van Loon, Jacques Tempere, Hadrien Kurkjian

  SciPost Phys. 12, 108 (2022) · published 28 March 2022 | Toggle abstract · pdf

  We study the fermionic quasiparticle spectrum in a zero-temperature superfluid Fermi gas, and in particular how it is modified by different disintegration processes. On top of the disintegration by emission of a collective boson ($1\to2$, subject of a previous study, PRL 124, 073404), we consider here disintegration events where three quasiparticles are emitted ($1\to3$). We show that both disintegration processes are described by a $t$-matrix self-energy (as well as some highly off-resonant vacuum processes), and we characterize the associated disintegration continua. At strong coupling, we show that the quasiparticle spectrum is heavily distorted near the $1\to3$ disintegration threshold. Near the dispersion minimum, where the quasiparticles remain well-defined, the main effect of the off-shell disintegration processes is to shift the location of the minimum by a value that corresponds to the Hartree shift in the BCS limit. With our approximation of the self-energy, the correction to the energy gap with respect to the mean-field result however remains small, in contrast with experimental measurements.

• Probing hadronic interaction models with the hybrid data of the Pierre Auger Observatory

  Jakub Vícha for the Pierre Auger Collaboration

  SciPost Phys. Proc. 13, 026 (2023) · published 29 September 2023 | Toggle abstract · pdf

  Presently large systematic uncertainties remain in the description of hadronic interactions at ultra-high energies and a fully consistent description of air-shower experimental data is yet to be reached. The amount of data collected by the Pierre Auger Observatory using simultaneously the fluorescence and surface detectors in the energy range 10$^{18.5}$ -10$^{19.0}$ eV has provided opportunity to perform a multi-parameter test of model predictions. We apply a global method to simultaneously fit the mass composition of cosmic rays and adjustments to the simulated depth of shower maximum, and hadronic signal at ground level. The best description of the hybrid data is obtained for a deeper scale of simulated depth of shower maximum than predicted by hadronic interaction models tuned to the LHC data. Consequently, the deficit of the simulated hadronic signal at ground level, dominated by muons, is alleviated with respect to the unmodified hadronic interaction models. Because of the size of the adjustments to simulated depth of shower maximum and hadronic signal and the large number of events in the sample, the statistical significance of these assumed adjustments is large, greater than 5$\sigma_{stat}$, even for the combination of the systematic experimental shifts within 1$\sigma_{sys}$ that are the most favorable for the models.

• Group invariants for Feynman diagrams

  Idrish Huet, Michel Rausch de Traubenberg, Christian Schubert

  SciPost Phys. Proc. 14, 031 (2023) · published 24 November 2023 | Toggle abstract · pdf

  It is well-known that the symmetry group of a Feynman diagram can give important information on possible strategies for its evaluation, and the mathematical objects that will be involved. Motivated by ongoing work on multi-loop multi-photon amplitudes in quantum electrodynamics, here I will discuss the usefulness of introducing a polynomial basis of invariants of the symmetry group of a diagram in Feynman-Schwinger parameter space.