Publications

Order by: publication date number of citations

• Muons in showers with energy $\boldsymbol{E_{0} \geq}$ 5 EeV and QGSjetII-04 and EPOS LHC models of hadronic interactions. Is there a muon deficit in the models?

  Stanislav Knurenko, Igor Petrov

  SciPost Phys. Proc. 13, 032 (2023) · published 29 September 2023 | Toggle abstract · pdf

  The paper presents data on the muon component with a threshold $\varepsilon_{thr} ≥$ 1 GeV. Air showers were registered at the Yakutsk array during almost 50 years of continuous air shower observations. The characteristics of muons are compared with calculations of QGSjetII-04 and EPOS LHC models for a proton and an iron nucleus. There is a muon deficit in the models, at energies greater than 5 EeV. To make an agreement between experimental data and simulations on muons, further tuning of the models is required.

• Fusion of low-entanglement excitations in 2D toric code

  Jing-Yu Zhao, Xie Chen

  SciPost Phys. 18, 106 (2025) · published 20 March 2025 | Toggle abstract · pdf

  On top of a $D$-dimensional gapped bulk state, Low Entanglement Excitations (LEE) on $d(<D)$-dimensional sub-manifolds can have extensive energy but preserves the entanglement area law of the ground state. Due to their multi-dimensional nature, the LEEs embody a higher-category structure in quantum systems. They are the ground state of a modified Hamiltonian and hence capture the notions of 'defects' of generalized symmetries. In previous works, we studied the low-entanglement excitations in a trivial phase as well as those in invertible phases. We find that LEEs in these phases have the same structure as lower-dimensional gapped phases and their defects within. In this paper, we study the LEEs inside non-invertible topological phases. We focus on the simple example of $\mathbb{Z}_2$ toric code and discuss how the fusion result of 1d LEEs with 0d morphisms can depend on both the choice of fusion circuit and the ordering of the fused defects.

• SUSY-QCD corrections to squark annihilation into gluons and light quarks

  Luca Paolo Wiggering

  SciPost Phys. Proc. 12, 047 (2023) · published 4 July 2023 | Toggle abstract · pdf

  We calculate the full one-loop SUSY-QCD corrections to stop annihilation into gluons and light quarks including the Sommerfeld enhancement effect and discuss their impact on the neutralino relic density in the MSSM.

• VERITAS highlights of observations and results

  Sonal R. Patel for the VERITAS collaboration

  SciPost Phys. Proc. 13, 035 (2023) · published 29 September 2023 | Toggle abstract · pdf

  Located in southern Arizona, VERITAS is amongst the most sensitive detectors for astrophysical very high energy (VHE; E>100 GeV) gamma rays and has been operational since April 2007. We highlight some recent results from VERITAS observations. These include the long-term observations of the gamma-ray binaries HESS J0632+057 and LS I +61° 303, the observations of the Galactic Center region, and of the supernova remnant Cas A. We discuss the results from a decade of multi-wavelength observations of the blazar 1ES 1215+303, the EHT 2017 campaign on the M87 galaxy, the discovery of 3C 264 in VHE, and the observation of three flaring quasars. Brief highlights of the indirect dark matter searches and targets-of-opportunity (ToO) observations are also discussed. The ToO observations allow for rapid follow-up of multi-messenger alerts and astrophysical transients.

• Spin of fractional quantum Hall neutral modes and “missing states” on a sphere

  Dung Xuan Nguyen, Dam Thanh Son

  SciPost Phys. 19, 131 (2025) · published 18 November 2025 | Toggle abstract · pdf

  A low-energy neutral quasiparticle in a fractional quantum Hall system appears in the latter's energy spectrum on a sphere as a series of many-body excited states labeled by the angular momentum $L$ and whose energy is a smooth function of $L$ in the limit of large sphere radius. We argue that the signature of a nonvanishing spin (intrinsic angular momentum) $s$ of the quasiparticle is the absence, in this series, of states with total angular momentum less than $s$. We reinterpret the missing of certain states, observed in an exact-diagonalization calculation of the spectrum of the $\nu=7/3$ FQH state in a wide quantum well as well as in many proposed wave functions for the excited states as a consequence of the spin-2 nature of the zero-momentum magnetoroton.

• Spin-$s$ $Q$-systems: Twist and open boundaries

  Yi-Jun He, Jue Hou, Yi-Chao Liu, Zi-Xi Tan

  SciPost Phys. Core 8, 057 (2025) · published 27 August 2025 | Toggle abstract · pdf

  In integrable spin chains, the spectral problem can be solved by the method of Bethe Ansatz, which transforms the problem of diagonalization of the Hamiltonian into the problem of solving a set of algebraic equations named Bethe equations. In this work, we systematically investigate the spin-$s$ XXX chain with twisted and open boundary conditions using the rational $Q$-system, which is a powerful tool to solve Bethe equations. We establish basic frameworks of the rational $Q$-system and confirm its completeness numerically in both cases. For twisted boundaries, we investigate the polynomiality conditions of the rational $Q$-system and derive physical conditions for singular solutions of Bethe equations. For open boundaries, we uncover novel phenomena such as hidden symmetries and boundary induced strings under specific boundary parameters. Hidden symmetries lead to the appearance of extra degeneracies in the Hilbert space, while the boundary induced string is a novel type of exact string configuration, whose length depends on the boundary magnetic fields. These findings, supported by both analytical and numerical evidences, offer new insights into the interplay between symmetries and boundary conditions.

• Study of light nuclei by polarization observables in electron scattering

  Simon Širca

  SciPost Phys. Proc. 3, 048 (2020) · published 27 February 2020 | Toggle abstract · pdf

  Electron-induced proton, neutron and deuteron knock-out remains the most versatile probe of the electro-magnetic properties and spin structure of light nuclei. The advent of highly polarized beams and targets and improvements in recoil polarization methods, as well as analysis and simulation techniques, have enabled us to study the static and dynamical properties of few-body systems with unprecedented precision. Recent experiments at Jefferson Lab and MAMI are presented and put into perspective of state-of-the art Faddeev calculations, with focus on the $^\mathbf{3}\mathbf{He}$ nucleus.

• A short introduction to cosmology and its current status

  Pedro G. Ferreira, Alexander Roskill

  SciPost Phys. Lect. Notes 109 (2025) · published 24 December 2025 | Toggle abstract · pdf

  The current cosmological model, known as the $\Lambda$-Cold Dark Matter model (or $\Lambda$CDM for short) is one of the most astonishing accomplishments of contemporary theoretical physics. It is a well-defined mathematical model which depends on very few ingredients and parameters and is able to make a range of predictions and postdictions with astonishing accuracy. It is built out of well-known physics – general relativity, quantum mechanics and atomic physics, statistical mechanics and thermodynamics – and predicts the existence of new, unseen components. Again and again it has been shown to fit new data sets with remarkable precision. Despite these successes, we have yet to understand the unseen components of the Universe and there has been evidence for inconsistencies in the model. In these lectures, we lay the foundations of modern cosmology.

• Lattice phase shifts and mixing angles for an arbitrary number of coupled channels

  Lukas Bovermann, Evgeny Epelbaum, Hermann Krebs, Dean Lee

  SciPost Phys. Proc. 3, 052 (2020) · published 27 February 2020 | Toggle abstract · pdf

  We present a lattice method for determining scattering phase shifts and mixing angles for the case of an arbitrary number of coupled channels. The proposed method combines a spherical wall boundary condition and a channel-mixing auxiliary potential to extract the full-rank S-matrix from the radial wave functions. We consider the scattering problem of two spin-1 bosons interacting with a test potential involving up to four coupled channels. For this benchmark system, the phase shifts and mixing angles are shown to agree on the lattice and in the continuum. Our method should allow to extend previous two-channel nuclear lattice EFT simulations to mixing of more than two partial waves.

• Revisiting the flavor violating decays of the Tau and Mu leptons in the Standard Model with massive neutrinos

  Gerardo Hernández Tomé

  SciPost Phys. Proc. 1, 017 (2019) · published 19 February 2019 | Toggle abstract · pdf

  The flavor violating leptonic decays of the $\tau$ and $\mu$ leptons into three lighter charged leptons are revisited in the framework the Standard Model with massive neutrinos. In contrast to the previous prediction, we have found strongly suppressed rates for the $\tau^-\to \mu^- \ell^+ \ell^-$ ($\ell=\mu, e$) decays. Our results are in good agreement with the approximation of neglecting masses and momenta of the external particles in the loop integrals made in the first computation for the $\mu^- \to e^-e^+ e^-$ decay.