Publications

Order by: publication date number of citations

• Out of equilibrium many-body expansion dynamics of strongly interacting bosons

  Rhombik Roy, Barnali Chakrabarti, Arnaldo Gammal

  SciPost Phys. Core 6, 073 (2023) · published 3 November 2023 | Toggle abstract · pdf

  We solve the Schrödinger equation from first principles to investigate the many-body effects in the expansion dynamics of one-dimensional repulsively interacting bosons released from a harmonic trap. We utilize the multiconfigurational time-dependent Hartree method for bosons (MCTDHB) to solve the many-body Schrödinger equation at high level of accuracy. The MCTDHB basis sets are explicitly time-dependent and optimised by variational principle. We probe the expansion dynamics by three key measures; time evolution of one-, two- and three-body densities. We observe when the mean-field theory results to unimodal expansion, the many-body calculation exhibits trimodal expansion dynamics. The many-body features how the initially fragmented bosons independently spreads out with time whereas the mean-field pictures the expansion of the whole cloud. We also present the three different time scale of dynamics of the inner core, outer core and the cloud as a whole. We analyze the key role played by the dynamical fragmentation during expansion. A Strong evidence of the many-body effects is presented in the dynamics of two- and three-body densities which exhibit correlation hole and pronounced delocalization effect.

• 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.

• 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.

• 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.

• Effect of isospin averaging for $ppK^-$ kaonic cluster

  Branislav Vlahovic, Igor Filikhin

  SciPost Phys. Proc. 3, 040 (2020) · published 27 February 2020 | Toggle abstract · pdf

  The kaonic cluster $ppK^-$ is described by isospin-dependent $N{\bar K}$ potentials with significant difference between singlet and triplet components. The quasi-bound state energy of the system is calculated based on the configuration space Faddeev equations within isospin and averaged potential models. The isospin averaging of $ N{\bar K} $ potentials is used to simplify the isospin model to isospinless one. We show that three-body bound state energy $E_{3}$ has a lower bound within the isospin formalism due to relation $\left\vert E_{3}(V_{NN}=0)\right\vert<2\left\vert E_{2}\right\vert$, where $E_{2}$ is the binding energy of isospin singlet state of the $N{\bar K}$ subsystem. The averaged potential model demonstrates opposite relation between $|E_{2}|$ and $|E_{3}(V_{NN}=0)|$.

• Top quark mass corrections to single and double Higgs boson production in gluon fusion

  Joshua Davies

  SciPost Phys. Proc. 7, 031 (2022) · published 21 June 2022 | Toggle abstract · pdf

  In this talk we discuss recent computations of the top quark mass dependence of QCD amplitudes describing Higgs boson production in gluon fusion. We compute terms in the expansion for a large top quark mass, which reduces the Feynman diagrams to products of massless integrals and massive tadpole integrals which contain the top mass dependence. In particular we discuss the real and virtual corrections to double Higgs production at NNLO, and the virtual corrections to single Higgs production at N3LO.

• Topological-insulator nanocylinders

  Michele Governale, Fabio Taddei

  SciPost Phys. Core 6, 032 (2023) · published 21 April 2023 | Toggle abstract · pdf

  Nanostructures, such a quantum dots or nanoparticles, made of three-dimensional topological insulators (3DTIs) have been recently attracting increasing interest, especially for their optical properties. In this paper we calculate the energy spectrum, the surface states and the dipole matrix elements for optical transitions with in-plane polarization of 3DTI nanocylinders of finite height $L$ and radius $R$. We first derive an effective 2D Hamiltonian by exploiting the cylindrical symmetry of the problem. We develop two approaches: the first one is an exact numerical tight-binding model obtained by discretising the Hamiltonian. The second one, which allows us to obtain analytical results, is an approximated model based on a large-$R$ expansion and on an effective boundary condition to account for the finite height of the nanocylinder. We find that the agreement between the two models, as far as eigenenergies and eigenfunctions are concerned, is excellent for the lowest absolute value of the longitudinal component of the angular momentum. Finally, we derive analytical expressions for the dipole matrix elements by first considering the lateral surface alone and the bases alone, and then for the whole nanocylinder. In particular, we focus on the two limiting cases of tall and squat nanocylinders. The latter case is compared with the numerical results finding a good agreement.

• Recent progress on two-loop massless pentabox integrals with one off-shell leg

  D. Canko, A. Kardos, C. G. Papadopoulos, A. V Smirnov, N. Syrrakos, C. Wever

  SciPost Phys. Proc. 7, 037 (2022) · published 21 June 2022 | Toggle abstract · pdf

  Analytic expressions in terms of polylogarithmic functions for all three families of planar two-loop five-point Master Integrals with one off-shell leg are presented. The Simplified Differential Equations approach is the only known way to fulfil this task due to its unique factorisation property of the symbols of the canonical differential equation. The results are relevant to the study of many $2\to 3$ scattering processes of interest at the LHC.

• Jet substructure observables for jet quenching in quark gluon plasma: A machine learning driven analysis

  Miguel Crispim Romão, José Guilherme Milhano, Marco van Leeuwen

  SciPost Phys. 16, 015 (2024) · published 18 January 2024 | Toggle abstract · pdf

  We present a survey of a comprehensive set of jet substructure observables commonly used to study the modifications of jets resulting from interactions with the Quark Gluon Plasma in Heavy Ion Collisions. The JEWEL event generator is used to produce simulated samples of quenched and unquenched jets. Three distinct analyses using Machine Learning techniques on the jet substructure observables have been performed to identify both linear and non-linear relations between the observables, and to distinguish the Quenched and Unquenched jet samples. We find that most of the observables are highly correlated, and that their information content can be captured by a small set of observables. We also find that the correlations between observables are resilient to quenching effects and that specific pairs of observables exhaust the full sensitivity to quenching effects. The code, the datasets, and instructions on how to reproduce this work are also provided.

• Three-loop soft anomalous dimensions in QCD

  Nikolaos Kidonakis

  SciPost Phys. Proc. 7, 046 (2022) · published 22 June 2022 | Toggle abstract · pdf

  I present results for soft anomalous dimensions through three loops for many QCD processes. In particular, I give detailed expressions for soft anomalous dimensions in various processes with electroweak and Higgs bosons as well as single top quarks and top-antitop pairs.