Publications

Order by: publication date number of citations

• Non-minimal coupling, negative null energy, and effective field theory

  Jackson R. Fliss, Ben Freivogel, Eleni-Alexandra Kontou, Diego Pardo Santos

  SciPost Phys. 16, 119 (2024) · published 2 May 2024 | Toggle abstract · pdf

  The non-minimal coupling of scalar fields to gravity has been claimed to violate energy conditions, leading to exotic phenomena such as traversable wormholes, even in classical theories. In this work we adopt the view that the non-minimal coupling can be viewed as part of an effective field theory (EFT) in which the field value is controlled by the theory's cutoff. Under this assumption, the average null energy condition, whose violation is necessary to allow traversable wormholes, is obeyed both classically and in the context of quantum field theory. In addition, we establish a type of "smeared" null energy condition in the non-minimally coupled theory, showing that the null energy averaged over a region of spacetime obeys a state dependent bound, in that it depends on the allowed field range. We finally motivate our EFT assumption by considering when the gravity plus matter path integral remains semi-classically controlled.

  1 citation

• Codebase release 1.1 for TASEPy

  Luca Ciandrini, Richmond L. Crisostomo, Juraj Szavits-Nossan

  SciPost Phys. Codebases 22-r1.1 (2023) · published 13 December 2023 | Toggle abstract · src

  The totally asymmetric simple exclusion process (TASEP) is a paradigmatic lattice model for one-dimensional particle transport subject to excluded-volume interactions. Solving the inhomogeneous TASEP in which particles' hopping rate vary across the lattice is a long-standing problem. In recent years, a power series approximation (PSA) has been developed to tackle this problem, however no computer algorithm currently exists that implements this approximation. This paper addresses this issue by providing a Python-based package TASEPy that finds the steady state solution of the inhomogeneous TASEP for any set of hopping rates using the PSA truncated at a user-defined order.

  1 citation

• Next generation proton PDFs with deuteron and nuclear uncertainties

  Rosalyn L. Pearson, Richard D. Ball, Emanuele R. Nocera

  SciPost Phys. Proc. 8, 026 (2022) · published 11 July 2022 | Toggle abstract · pdf

  As data become more precise, estimating theoretical uncertainties in global PDF determinations is likely to become increasingly necessary to obtain correspondingly precise PDFs. Here we present a next generation of global proton PDFs (NNPDF4.0) that include theoretical uncertainties due to the use of heavy nuclear and deuteron data in the fit. We estimate these uncertainties by comparing the values of the nuclear observables computed with the nuclear PDFs against those computed with proton PDFs. For heavy nuclear PDFs we use the nuclear nNNPDF2.0 set, while for deuteron PDFs we develop an iterative procedure to determine proton and deuteron PDFs simultaneously, each including the uncertainties in the other. Accounting for nuclear uncertainties resolves some of the tensions in the global fit of the proton PDFs, especially those between the nuclear data and the extended LHC data set used in NNPDF4.0.

  1 citation

• Connected and Disconnected Sea Partons from CT18 Parametrization of PDFs

  Tie-Jiun Hou, Jian Liang, Keh-Fei Liu, Mengshi Yan, C.-P. Yuan

  SciPost Phys. Proc. 8, 067 (2022) · published 12 July 2022 | Toggle abstract · pdf

  The separation of the connected and disconnected sea partons, which were uncovered in the Euclidean path-integral formulation of the hadronic tensor, is accommodated with the CT18 parametrization of the global analysis of the parton distribution functions (PDFs). This is achieved with the help of the distinct small $x$ behaviors of these two sea parton components and the constraint from the lattice calculation of the ratio of the strange momentum fraction to that of the ${\bar u}$ or ${\bar d}$ in the disconnected insertion. This allows lattice calculations of separate flavors in both the connected and disconnected insertions to be directly compared with the global analysis results term by term.

  1 citation

• Tensor network variational optimizations for real-time dynamics: Application to the time-evolution of spin liquids

  Ravi Teja Ponnaganti, Matthieu Mambrini, Didier Poilblanc

  SciPost Phys. 15, 158 (2023) · published 12 October 2023 | Toggle abstract · pdf

  Within the Projected Entangled Pair State (PEPS) tensor network formalism, a simple update (SU) method has been used to investigate the time evolution of a two-dimensional U(1) critical spin-1/2 spin liquid under Hamiltonian quench [Phys. Rev. B 106, 195132 (2022)]. Here we introduce two different variational frameworks to describe the time dynamics of SU(2)-symmetric translationally-invariant PEPS, aiming to improve the accuracy. In one approach, after using a Trotter-Suzuki decomposition of the time evolution operator in term of two-site elementary gates, one considers a single bond embedded in an environment approximated by a Corner Transfer Matrix Renormalization Group (CTMRG). A variational update of the two tensors on the bond is performed under the application of the elementary gate and then, after symmetrization of the site tensors, the environment is updated. In the second approach, a cluster optimization is performed on a finite (periodic) cluster, maximizing the overlap of the exact time-evolved state with a symmetric finite-size PEPS ansatz. Observables are then computed on the infinite lattice contracting the infinite-PEPS (iPEPS) by CTMRG. We show that the variational schemes outperform the SU method and remain accurate over a significant time interval before hitting the entanglement barrier. Studying the spectrum of the transfer matrix, we find that the asymptotic correlations are very well preserved under time evolution, including the critical nature of the singlet correlations, as expected from the Lieb-Robinson (LR) bound theorem. Consistently, the system (asymptotic) boundary is found to be described by the same Conformal Field Theory of central charge $c = 1$ during time evolution. We also compute the time-evolution of the short distance spin-spin correlations and estimate the LR velocity.

  1 citation

• Nuclear matter effects on jet production at electron-ion colliders

  Hai Tao Li, Ze Long Liu, Ivan Vitev

  SciPost Phys. Proc. 8, 134 (2022) · published 14 July 2022 | Toggle abstract · pdf

  In these proceedings we report recent progress on understanding hadron and jet production in electron-nucleus collisions at the future Electron-Ion Collider [1,2]. These processes will play an essential role in the exploration of the partonic structure of nuclei and the study of parton shower evolution in strongly-interacting matter. We employ the framework of soft-collinear effective theory, generalized to include in-medium interactions, to present the first theoretical results for inclusive hadron and jet cross sections, as well as the jet charge modification in deep inelastic scattering on nuclei. We further demonstrate how to separate initial-state and final-state effects.

  1 citation

• A NEAT quantum error decoder

  Hugo Théveniaut, Evert van Nieuwenburg

  SciPost Phys. 11, 005 (2021) · published 12 July 2021 | Toggle abstract · pdf

  We investigate the use of the evolutionary NEAT algorithm for the optimization of a policy network that performs quantum error decoding on the toric code, with bitflip and depolarizing noise, one qubit at a time. We find that these NEAT-optimized network decoders have similar performance to previously reported machine-learning based decoders, but use roughly three to four orders of magnitude fewer parameters to do so.

  1 citation

• Current mean values in the XYZ model

  Levente Pristyák, Balázs Pozsgay

  SciPost Phys. 14, 158 (2023) · published 15 June 2023 | Toggle abstract · pdf

  The XYZ model is an integrable spin chain which has an infinite set of conserved charges, but it lacks a global $U(1)$-symmetry. We consider the current operators, which describe the flow of the conserved quantities in this model. We derive an exact result for the current mean values, valid for any eigenstate in a finite volume with periodic boundary conditions. This result can serve as a basis for studying the transport properties of this model within Generalized Hydrodynamics.

  1 citation

• Searches for additional Higgs bosons decaying to tau leptons at the LHC

  Claudio Caputo on behalf of the ATLAS an CMS collaborations

  SciPost Phys. Proc. 1, 022 (2019) · published 20 February 2019 | Toggle abstract · pdf

  The searches for additional Higgs bosons decaying to tau leptons in scenarios beyond the standard model will be summarised, from the pp collision data collected by the ATLAS and CMS experiments at LHC Run-2.

  1 citation

• Intermittency in pp collisions at $\sqrt{s}=$ 0.9, 7 and 8 TeV from the CMS collaboration

  Z. Ong, P. Agarwal, H. W. Ang, A. H. Chan, C. H. Oh

  SciPost Phys. Proc. 10, 032 (2022) · published 11 August 2022 | Toggle abstract · pdf

  The intermittency-type fluctuations as outlined by Bialas and Peschanski in the 1980s is analysed in $pp$ collisions at $\sqrt{s}=$ 0.9, 7 and 8 TeV from the CMS collaboration at CERN. Our preliminary analysis shows that the intermittency exponents in the bin-averaged scaled factorial moments decrease in magnitude with increasing collision energy at the TeV scale, which suggests that the cascading nature of multiparticle production described by the $\alpha$-model is weakening. We outline possible areas planned for future studies.

  1 citation