Publications

Order by: publication date number of citations

• $tW$ and $tZ'$ production at hadron colliders

  Nikolaos Kidonakis, Marco Guzzi, Nodoka Yamanaka

  SciPost Phys. Proc. 8, 064 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We present theoretical results with soft-gluon corrections for two separate processes: (1) the production of a single top quark in association with a $W$ boson in the Standard Model; and (2) the production of a single top quark in association with a heavy $Z'$ boson in new physics models with or without anomalous couplings. We show that the higher-order corrections from soft-gluon emission are dominant for a wide range of collider energies. Results are shown for the total cross sections and top-quark transverse-momentum and rapidity distributions for $tW$ and $tZ'$ production at LHC and future collider energies up to 100 TeV. The uncertainties from scale dependence and parton distribution functions are also analyzed.

• Status and prospects for $\tau$ property measurements at Belle II

  Michel Hernández Villanueva

  SciPost Phys. Proc. 16, 015 (2025) · published 14 July 2025 | Toggle abstract · pdf

  Belle II is a major upgrade of the Belle detector, operating at the SuperKEKB asymmetric-energy $e^+e^-$ collider with a design luminosity of 8×$10^{35}$ cm$^{-2}$s$^{-1}$. To date, the detector has recorded over 200 fb$^{-1}$ of data and aims to collect 50 ab$^{-1}$, a factor of 50 more than its predecessor. Belle II has a broad $\tau$ physics program, from high-precision measurements of Standard Model parameters to searches of new non-Standard-Model interactions. In this work, we review the status of the Belle II experiment and the prospects for the measurement of the $\tau$ lepton mass and lifetime, which are fundamental inputs in tests of LFU violation.

• Feasibility of tau g-2 measurements in ultra-peripheral collisions of heavy ions

  Nazar Burmasov, Evgeny Kryshen, Paul Buehler, Roman Lavicka

  SciPost Phys. Proc. 16, 022 (2025) · published 15 July 2025 | Toggle abstract · pdf

  The anomalous magnetic moment of the tau lepton, $a_\tau=(g_\tau - 2)/2$, is a sensitive probe of new physics but is extremely difficult to measure precisely in contrast to electron and muon moments. The best experimental limits were set by the DELPHI collaboration more than 15 years ago in studies of the ditau production in the $ee\to ee\tau\tau$ process. Ultra-peripheral collisions (UPCs) of heavy ions at the LHC may provide a unique opportunity to improve the $a_\tau$ constraints in the studies of ${\rm Pb + Pb}\to {\rm Pb + Pb}+\tau\tau$ process. We review recent proposals to study ditau production via semi-leptonic tau decays in Pb-Pb UPC with the available ATLAS and CMS data and discuss the feasibility to explore this process down to low transverse momenta of decay leptons with the ALICE and LHCb experiments.

• Nucleon and pion PDFs: large-x asymptotics meets functional mimicry

  Aurore Courtoy, Pavel M. Nadolsky

  SciPost Phys. Proc. 8, 063 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We review strategies to unveil the primordial large-$x$ structure of the nucleons as well as the pion from hard-scattering experiments. Ideas are presented for learning about the $x\to 1$ limit of nonperturbative QCD dynamics at energy scales of order 1 GeV from collider experiments at much higher scales. The behavior of parton distributions at $x\to 1$ predicted by the quark counting rules and other low-energy theoretical approaches is contrasted with phenomenological PDFs. Polynomial mimicry of PDF parametrizations is one of many factors that influence the apparent power of the $(1-x)$ falloff. We discuss implications of the mimicry for the large-$x$ falloff of the pion PDFs.

• Interaction and collision of skyrmions in chiral antiferromagnets

  George Theodorou, Bruno Barton-Singer, Stavros Komineas

  SciPost Phys. 18, 037 (2025) · published 30 January 2025 | Toggle abstract · pdf

  Skyrmions in an antiferromagnet can travel as solitary waves in stark contrast to the situation in ferromagnets. Traveling skyrmion solutions have been found numerically in chiral antiferromagnets. We study head-on collision events between two skyrmions. We find that the result of the collision depends on the initial velocity of the skyrmions. For small velocities, the skyrmions shrink as they approach, then bounce back and eventually acquire almost their initial speed. For larger velocities, the skyrmions approach each other and shrink until they become singular points at some finite separation and are eventually annihilated. Considering skyrmion energetics, we can determine the regimes of the different dynamical behaviors. Using a collective co-ordinate approach, we reproduce the dynamics of the collisions including the variation of the size of the skyrmions and collapse above a critical velocity.

• ATLAS LAr Calorimeter commissioning for LHC Run-3

  Luka Selem

  SciPost Phys. Proc. 8, 157 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The ATLAS experiment at the Large Hadron Collider (LHC) measures proton--proton collisions at high energies. Within the Phase-I upgrade of the LHC before the start of Run-3 in 2022, the trigger system of the Liquid Argon calorimeter of ATLAS is being prepared to cope with an increased number of simultaneous proton--proton collisions. In the back-end of this new trigger system, the LATOME boards will be responsible for the computation of the energies deposited in the calorimeter. The commissioning of this computation within the LATOME is presented.

• Development of the ATLAS Liquid Argon Calorimeter Readout Electronics for the HL-LHC

  Mathis Kolb

  SciPost Phys. Proc. 8, 158 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The full ATLAS Liquid Argon Calorimeter electronic readout chain will be upgraded for the high-luminosity LHC. The upgrade is designed to withstand the expected radiation level and to be compatible with the Phase-I Digital Trigger System which is being installed right now. Analogue electronics shape and amplify the calorimeter signals before they are digitized with 16 bit dynamic range on two gain scales. The on-detector system samples the calorimeter cell signals at 40 MHz and sends them to the off-detector electronics which apply digital processing based on FPGAs. Design studies and tests of prototypes of the upgraded components are present

• Critical dynamics and cyclic memory retrieval in non-reciprocal Hopfield networks

  Shuyue Xue, Mohammad Maghrebi, George I. Mias, Carlo Piermarocchi

  SciPost Phys. 19, 100 (2025) · published 16 October 2025 | Toggle abstract · pdf

  We study Hopfield networks with non-reciprocal coupling inducing switches between memory patterns. Dynamical phase transitions occur between phases of no memory retrieval, retrieval of multiple point-attractors, and limit-cycles. The limit cycle phase is bounded by a Hopf bifurcation line and a fold bifurcation line. Autocorrelation scales as $\tilde{C}(\tau/N^\zeta)$, with $\zeta = 1/2$ on the Hopf line and $\zeta = 1/3$ on the fold line. Perturbations of strength $F$ on the Hopf line exhibit response times scaling as $|F|^{-2/3}$, while they induce switches in a controlled way within times scaling as $|F|^{-1/2}$ in the fold line. A Master Equation approach numerically verifies the critical behavior predicted analytically. We discuss how these networks could model biological processes near a critical threshold of cyclic instability evolving through multi-step transitions.

• Dynamically restoring conformal invariance in (integrable) $\sigma$-models

  Rigers Aliaj, Konstantinos Sfetsos, Konstantinos Siampos

  SciPost Phys. 14, 043 (2023) · published 21 March 2023 | Toggle abstract · pdf

  Integrable $\lambda$-deformed $\sigma$-models are characterized by an underlying current algebra/coset model CFT deformed, at the infinitesimal level, by current/parafermion bilinears. We promote the deformation parameters to dynamical functions of time introduced as an extra coordinate. It is conceivable that by appropriately constraining them, the beta-functions vanish and consequently the $\sigma$-model stays conformal. Remarkably, we explicitly materialize this scenario in several cases having a single and even multiple deformation parameters. These generically obey a system of non-linear second-order ordinary differential equations. They are solved by the fixed points of the RG flow of the original $\sigma$-model. Moreover, by appropriately choosing initial conditions we may even interpolate between the RG fixed points as the time varies from the far past to the far future. Finally, we present an extension of our analysis to the Yang--Baxter deformed PCMs.

• Phase transitions in quantum dot-Majorana zero mode coupling systems

  Yue Mao, Qing-Feng Sun

  SciPost Phys. Core 8, 031 (2025) · published 11 March 2025 | Toggle abstract · pdf

  The magnetic doublet ground state (GS) of a quantum dot (QD) could be changed to a spin-singlet GS by coupling to a superconductor. In analogy, here we study the GS phase transitions in QD-Majorana zero mode (MZM) coupling systems: GS behaves phase transition versus intra-dot energy level and QD-MZM coupling strength. The phase diagrams of GS are obtained, for cases with and without Zeeman term. Along with the phase transition, we also study the change of spin feature and density of states. The properties of the phase transition are understood via a mean-field picture. Our study not only serves as an analogue to QD-superconductor phase transitions, but also gives alternative explanations on MZM-relevant experiments.