Publications

Order by: publication date number of citations

• Quantum to classical mapping of the two-dimensional toric code in an external field

  Sydney R. Timmerman, Zvonimir Z. Bandic, Roger G. Melko

  SciPost Phys. Lect. Notes 57 (2022) · published 20 July 2022 | Toggle abstract · pdf

  Kitaev's toric code Hamiltonian in dimension D=2 has been extensively studied for its topological properties, including its quantum error correction capabilities. While the Hamiltonian is quantum, it lies within the class of models that admits a D+1 dimensional classical representation. In these notes, we provide details of a Suzuki-Trotter expansion of the partition function of the toric code Hamiltonian in the presence of an external magnetic field. By coupling additional degrees of freedom in the form of a matter field that can subsequently be gauged away, we explicitly derive a classical Hamiltonian on a cubic lattice which takes the form of a non-isotropic 3D Ising gauge theory.

  2 citations

• Probing the Inflaton Potential with SKA

  Tanmoy Modak, Tilman Plehn, Lennart Röver, Björn Malte Schäfer

  SciPost Phys. Core 5, 037 (2022) · published 18 July 2022 | Toggle abstract · pdf

  SKA will be a major step forward not only in astrophysics, but also in precision cosmology. We show how the neutral hydrogen intensity map can be combined with the Planck measurements of the CMB power spectrum, to provide a precision test of the inflaton potential. For a conservative range of redshifts we find that SKA can significantly improve current constraints on the Hubble slow-roll parameters.

  1 citation

• Classical and quantum harmonic mean-field models coupled intensively and extensively with external baths

  Francesco Andreucci, Stefano Lepri, Stefano Ruffo, Andrea Trombettoni

  SciPost Phys. Core 5, 036 (2022) · published 15 July 2022 | Toggle abstract · pdf

  We study the nonequilibrium steady-state of a fully-coupled network of $N$ quantum harmonic oscillators, interacting with two thermal reservoirs. Given the long-range nature of the couplings, we consider two setups: one in which the number of particles coupled to the baths is fixed (intensive coupling) and one in which it is proportional to the size $N$ (extensive coupling). In both cases, we compute analytically the heat fluxes and the kinetic temperature distributions using the nonequilibrium Green's function approach, both in the classical and quantum regimes. In the large $N$ limit, we derive the asymptotic expressions of both quantities as a function of $N$ and the temperature difference between the baths. We discuss a peculiar feature of the model, namely that the bulk temperature vanishes in the thermodynamic limit, due to a decoupling of the dynamics of the inner part of the system from the baths. At variance with usual cases, this implies that the steady state depends on the initial state of the particles in the bulk. We also show that quantum effects are relevant only below a characteristic temperature that vanishes as $1/N$. In the quantum low-temperature regime the energy flux is proportional to the universal quantum of thermal conductance.

  4 citations

• Picking the low-hanging fruit: testing new physics at scale with active learning

  Juan Rocamonde, Louie Corpe, Gustavs Zilgalvis, Maria Avramidou, Jon Butterworth

  SciPost Phys. 13, 002 (2022) · published 15 July 2022 | Toggle abstract · pdf

  Since the discovery of the Higgs boson, testing the many possible extensions to the Standard Model has become a key challenge in particle physics. This paper discusses a new method for predicting the compatibility of new physics theories with existing experimental data from particle colliders. By using machine learning, the technique obtained comparable results to previous methods (>90% precision and recall) with only a fraction of their computing resources (<10%). This makes it possible to test models that were impossible to probe before, and allows for large-scale testing of new physics theories.

  4 citations

• The Return of the Singularities: Applications of the Smeared Null Energy Condition

  Ben Freivogel, Eleni-Alexandra Kontou, Dimitrios Krommydas

  SciPost Phys. 13, 001 (2022) · published 15 July 2022 | Toggle abstract · pdf

  The classic singularity theorems of General Relativity rely on energy conditions that can be violated in semiclassical gravity. Here, we provide motivation for an energy condition obeyed by semiclassical gravity: the smeared null energy condition (SNEC), a proposed bound on the weighted average of the null energy along a finite portion of a null geodesic. We then prove a semiclassical singularity theorem using SNEC as an assumption. This theorem extends the Penrose theorem to semiclassical gravity. We also apply our bound to evaporating black holes and the traversable wormhole of Maldacena-Milekhin-Popov, and comment on the relationship of our results to other proposed semiclassical singularity theorems.

  2 citations

• Resummation of the Sivers asymmetry in heavy flavor dijet production at the Electron-Ion Collider

  Zhong-Bo Kang, Jared Reiten, Ding Yu Shao, John Terry

  SciPost Phys. Proc. 8, 175 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We review our transverse momentum dependent factorization and resummation formalism for heavy flavor dijet production at the EIC. In this formalism, we have calculated the heavy flavor mass corrections in the collinear-soft and jet functions, and in the resummed expression for the cross section. By establishing this formalism, we then study the effects of the mass corrections by providing predictions at the EIC for the massive case and for the case where the mass is neglected. We find that the heavy flavor mass effects can give sizable corrections to the predicted asymmetry.

• Transverse-momentum-dependent parton distribution functions for spin-1 hadrons

  S. Kumano, Qin-Tao Song

  SciPost Phys. Proc. 8, 174 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We show transverse-momentum-dependent parton distribution functions (TMDs) for spin-1 hadrons including twist-3 and 4 functions by taking the decomposition of a quark correlation function in the Lorentz-invariant way with the conditions of Hermiticity and parity invariance. We found 30 new TMDs in the tensor-polarized spin-1 hadron at twists 3 and 4 in addition to 10 TMDs at twist 2. Since time-reversal-odd terms of the collinear correlation function should vanish after integrals over the partonic transverse momentum, we obtained new sum rules for the time-reversal-odd structure functions, ${\int d^2 k_T g_{LT} = \int d^2 k_T h_{LL} = \int d^2 k_T h_{3LL} =0}$, at twists 3 and 4. We also indicated that transverse-momentum-dependent fragmentation functions exist in tensor-polarized spin-1 hadrons. The TMDs can probe color degrees of freedom, so that they are valuable in providing unique opportunities for creating interdisciplinary physics fields such as gluon condensate, color Aharonov-Bohm effect, and color entanglement. We also found three new collinear PDFs at twists 3 and 4, and a twist-2 relation and a sum rule were derived in analogy to the Wandzura-Wilczek relation and the Burkhardt-Cottingham sum rule on the structure function ${g_2}$.

• Top-quark mass determination in the optimised threshold scan

  Kacper Nowak, Aleksander Filip Zarnecki

  SciPost Phys. Proc. 8, 173 (2022) · published 14 July 2022 | Toggle abstract · pdf

  One of the important goals at the future e$^+$e$^−$ colliders is to measure the top-quark mass and width in a scan of the pair production threshold. Presented in this work is the most general approach to the top-quark mass determination from the threshold scan at CLIC, with all relevant model parameters and selected systematic uncertainties included in the fit procedure. In the baseline scan scenario the top-quark mass can be extracted with precision of the order of 30 to 40 MeV, already for 100 fb$^{−1}$ of data collected at the threshold. We present the optimisation procedure based on the genetic algorithm with which the statistical uncertainty of the mass measurement can be reduced by about 20%.

• Valence quark distributions of light mesons in light-cone quark model

  Satvir Kaur, Narinder Kumar, Jiangshan Lan, Chandan Mondal, Harleen Dahiya

  SciPost Phys. Proc. 8, 172 (2022) · published 14 July 2022 | Toggle abstract · pdf

  In order to investigate the tomographical structure of light pseudoscalar mesons, particularly, pion and kaon, we study the valence quark distribution function (PDF) and the generalized parton distributions (GPDs) using light-cone quark model (LCQM).

• The ATLAS Tile Calorimeter performance and its upgrade towards the High Luminosity Large Hadron Collider

  Ryan Mckenzie

  SciPost Phys. Proc. 8, 171 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The Tile Calorimeter (TileCal) is a sampling calorimeter that forms the central region of the hadronic calorimeter of the ATLAS experiment. This sub-detector is to undergo its Phase-II upgrade during long-shutdown 3, in the years from 2025 to mid 2027, in preparation for the start of operation of the High Luminosity Large Hadron Collider (HL-LHC) in 2027. In this proceeding, an overview of the TileCal HL-LHC on-detector electronics upgrade is provided. The detectors Run-II performance in the cases of EM scale calibration, calorimeter response, cell energy distribution and noise as well as a portion of the 2015-2018 Test-beam campaigns results are examined.