Publications

Order by: publication date number of citations

• A brief note on the G$_2$ Affleck-Kennedy-Lieb-Tasaki chain

  Hosho Katsura, Dirk Schuricht

  SciPost Phys. Core 8, 052 (2025) · published 15 August 2025 | Toggle abstract · pdf

  We consider the valence bond solid (VBS) state built of singlet pairs of fundamental representations and projected onto adjoint representations of the exceptional Lie group G$_2$. The two-point correlation function in the VBS state is non-vanishing only for nearest neighbours, but possesses finite string order. We construct a parent Hamiltonian for the VBS state, which constitutes the G$_2$ analog of the famous AKLT chain.

• Nonequilibrium steady-state dynamics of Markov processes on graphs

  Stefano Crotti, Thomas Barthel, Alfredo Braunstein

  SciPost Phys. 19, 045 (2025) · published 18 August 2025 | Toggle abstract · pdf

  We propose an analytic approach for the steady-state dynamics of Markov processes on locally tree-like graphs. It is based on time-translation invariant probability distributions for edge trajectories, which we encode in terms of infinite matrix products. For homogeneous ensembles on regular graphs, the distribution is parametrized by a single $d× d× r^2$ tensor, where $r$ is the number of states per variable, and $d$ is the matrix-product bond dimension. While the method becomes exact in the large-$d$ limit, it typically provides highly accurate results even for small bond dimensions $d$. The $d^2r^2$ parameters are determined by solving a fixed point equation, for which we provide an efficient belief-propagation procedure. We apply this approach to a variety of models, including Ising-Glauber dynamics with symmetric and asymmetric couplings, as well as the SIS model. Even for small $d$, the results are compatible with Monte Carlo estimates and accurately reproduce known exact solutions. The method provides access to precise temporal correlations, which, in some regimes, would be virtually impossible to estimate by sampling.

• Phenomenological study on correlation between flow harmonics and mean transverse momentum in nuclear collisions

  Chunjian Zhang, Jiangyong Jia, Shengli Huang

  SciPost Phys. Proc. 10, 009 (2022) · published 10 August 2022 | Toggle abstract · pdf

  To assess the properties of the quark-gluon plasma formed in nuclear collisions, the Pearson correlation coefficient between flow harmonics and mean transverse momentum, $\rho\left(v_{n}^{2},\left[p_{\mathrm{T}}\right]\right)$, reflecting the overlapped geometry of colliding atomic nuclei, is measured. $\rho\left(v_{2}^{2},\left[p_{\mathrm{T}}\right]\right)$ was found to be particularly sensitive to the quadrupole deformation of the nuclei. We study the influence of the nuclear quadrupole deformation on $\rho\left(v_{n}^{2},\left[p_{\mathrm{T}}\right]\right)$ in $\rm{Au+Au}$ and $\rm{U+U}$ collisions at RHIC energy using $\rm{AMPT}$ transport model, and show that the $\rho\left(v_{2}^{2},\left[p_{\mathrm{T}}\right]\right)$ is reduced by the prolate deformation $\beta_2$ and turns to change sign in ultra-central collisions (UCC).

• Twisted S-duality

  Surya Raghavendran, Philsang Yoo

  SciPost Phys. 19, 049 (2025) · published 20 August 2025 | Toggle abstract · pdf

  We study an $\mathrm{SL}(2, \mathbb{Z})$ symmetry of a variant of BCOV theory in three complex dimensions. Using conjectural descriptions of twists of superstrings in terms of topological strings, we argue that this action can be thought of as a version of S-duality that preserves an $\mathrm{SU}(3)$-invariant twist of type IIB supergravity. We analyze how $\mathrm{SL}(2, \mathbb{Z})$ acts on various deformations of the holomorphic-topological twist of 4-dimensional $\mathcal{N}=4$ supersymmetric gauge theory, which come from residual supertranslations and superconformal symmetries, and are of relevance to geometric Langlands theory and gauge-theoretic constructions of the Yangian.

• Physics-informed neural networks viewpoint for solving the Dyson-Schwinger equations of quantum electrodynamics

  Rodrigo Carmo Terin

  SciPost Phys. Core 8, 054 (2025) · published 20 August 2025 | Toggle abstract · pdf

  Physics-informed neural networks (PINNs) are employed to solve the Dyson-Schwinger equations of quantum electrodynamics (QED) in Euclidean space, with a focus on the non-perturbative generation of the fermion's dynamical mass function in the Landau gauge. By inserting the integral equation directly into the loss function, our PINN framework enables a single neural network to learn a continuous and differentiable representation of the mass function over a spectrum of momenta. Also, we benchmark our approach against a traditional numerical algorithm showing the main differences among them. Our novel strategy, which is expected to be extended to other quantum field theories, is the first step towards forefront applications of machine learning in high-level theoretical physics.

• Measuring single-top-associated Higgs production at the HL-LHC

  Henning Bahl

  SciPost Phys. Proc. 8, 010 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Precision measurements of top-associated Higgs production are an important ingredient to unravel the $\mathcal{CP}$ nature of the Higgs boson. In this work, we constraint the $\mathcal{CP}$ nature of the top-Yukawa coupling taking into account all relevant inclusive and differential Higgs boson measurements. Based upon this fit, we show that it is crucial to disentangle single- and di-top-associated Higgs production for tightening indirect constraints on a $\mathcal{CP}$-odd top-Yukawa coupling in the future. In this context, we propose an analysis strategy for measuring $tH$ production at the HL-LHC without relying on assumptions about the Higgs $\mathcal{CP}$ character.

• Ultraperipheral collisions and low-x physics

  Tuomas Lappi

  SciPost Phys. Proc. 8, 003 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Ultraperipheral collisions at the LHC and RHIC offer the highest currently available energy for photon-nucleon and photon-nucleus collisions. Thus they are a valuable tool for studying the gluonic structure of hadrons and nuclei at small x. We discuss recent theoretical work towards understanding such exclusive processes at NLO accuracy in QCD perturbation theory. These theoretical advances are also immediately relevant for understanding the physics of deep inelastic scattering at small x. We also discuss experimental results in ultraperipheral collisions, most prominently for exclusive vector meson production.

• Exponential enhancement of dark matter freezeout abundance

  Bibhushan Shakya

  SciPost Phys. Proc. 12, 070 (2023) · published 5 July 2023 | Toggle abstract · pdf

  A novel paradigm for thermal dark matter (DM), termed "bouncing dark matter", is presented. In canonical thermal DM scenarios, the DM abundance falls exponentially as the temperature drops below the mass of DM, until thermal freezeout occurs. This note explores a broader class of thermal DM models that are exceptions to this rule, where the DM abundance can deviate from the exponentially falling curve, and even rise exponentially, while in thermal equilibrium. Such scenarios can feature present day DM annihilation cross sections much larger than the canonical thermal target, improving the prospects for indirect detection of DM annihilation signals.

• Muonium reaction in MgO: A showcase for the final steps of ion implantation

  Rui C. Vilão, Ali Roonkiani, Apostolos G. Marinopoulos, Helena V. Alberto, João M. Gil, Ricardo B. L. Vieira, Robert Scheuermann, Alois Weidinger

  SciPost Phys. Core 8, 056 (2025) · published 26 August 2025 | Toggle abstract · pdf

  We present an in-depth investigation of the implantation of positive muons in magnesium oxide (MgO). Muonium, the positive muon plus an electron is an analogue of the hydrogen atom. This study describes the final stage of the implantation process, from muon diffusion over the potential barrier and the stopping by an inelastic reaction to the final embedding of the muon into the lattice structure. A special aspect is a relatively long-lived intermediate configuration which lasts for several hundred nanoseconds or more and is accessible to muon spin spectroscopy. The model presented here provides a framework for the analysis of the general case of ion implantation.

• Mixed QCD-electroweak corrections to $Z$ and $W$ boson production and their impact on the $W$ mass measurements at the LHC

  Arnd Behring

  SciPost Phys. Proc. 7, 003 (2022) · published 20 June 2022 | Toggle abstract · pdf

  We report on recently computed mixed QCD-electroweak corrections to on-shell $W$ and $Z$ boson production. We use these differential predictions to estimate their impact on the $W$ boson mass determination at the LHC.