Publications

Order by: publication date number of citations

• Sparks in the dark

  Olga Sunneborn Gudnadottir, Axel Gallén, Giulia Ripellino, Jochen J. Heinrich, Raazesh Sainudiin, Rebeca Gonzalez Suarez

  SciPost Phys. 18, 080 (2025) · published 4 March 2025 | Toggle abstract · pdf

  This study presents a novel method for the definition of signal regions in searches for new physics at collider experiments. By leveraging multi-dimensional histograms with precise arithmetic and utilizing the SparkDensityTree library, it is possible to identify high-density regions within the available phase space, potentially improving sensitivity to very small signals. Inspired by a search for dark mesons at the ATLAS experiment, CMS open data is used for this proof-of-concept intentionally targeting an already excluded signal. Signal regions are defined based on density estimates of signal and background. These preliminary regions align well with the physical properties of the signal while effectively rejecting background events.

• NLO QCD corrections for off-shell $t\bar{t}b\bar{b}$

  Michele Lupattelli

  SciPost Phys. Proc. 7, 006 (2022) · published 20 June 2022 | Toggle abstract · pdf

  We present a full off-shell NLO QCD calculation of $pp \rightarrow e^+ \nu_e b \mu^- \bar{\nu}_\mu \bar{b} b \bar{b} + X$. Results are obtained using the \textsc{Helac-Nlo} Monte Carlo framework. We discuss a comparison to previous results and to experimental measurements. We also investigate the contribution of the initial states involving $b$-quarks and we introduce two $b$-jet tagging schemes.

• Josephson current through the SYK model

  Luca Dell'Anna

  SciPost Phys. 17, 120 (2024) · published 24 October 2024 | Toggle abstract · pdf

  We calculate the equilibrium Josephson current through a disordered interacting quantum dot described by a Sachdev-Ye-Kitaev model fully contacted by two BCS superconductors, such that all modes of the dot contribute to the coupling, which encodes hopping and spin-flip processes. We show that, at zero temperature and at the conformal limit, i.e. in the strong interacting limit, the Josephson current is suppressed by $U$, the strength of the interaction, as ln(U)/U and becomes universal, namely it gets independent on the superconducting gap. At finite temperature, instead, it depends on the ratio between the gap and the temperature. A proximity effect exists but the self-energy corrections induced by the coupling with the superconducting leads seem subleading as compared to the interaction self-energy and the tunneling matrix for large number of particles. Finally we compare the results of the original four-fermion model with those obtained considering zero interaction, two-fermions and a generalized $q$-fermion model.

• A Fermi surface descriptor quantifying the correlations between anomalous Hall effect and Fermi surface geometry

  Elena Derunova, Jacob Gayles, Yan Sun, Michael W. Gaultois, Mazhar N. Ali

  SciPost Phys. Core 8, 085 (2025) · published 18 November 2025 | Toggle abstract · pdf

  In the last few decades, basic ideas of topology have completely transformed the prediction of quantum transport phenomena. Following this trend, we go deeper into the incorporation of modern mathematics into quantum material science focusing on geometry. Here we investigate the relation between the geometrical type of the Fermi surface and Anomalous and Spin Hall Effects. An index, $\mathbb{H}_F$, quantifying the hyperbolic geometry of the Fermi surface, shows a universal correlation (R$^2$ = 0.97) with the experimentally measured intrinsic anomalous Hall conductivity, of 16 different compounds spanning a wide variety of crystal, chemical, and electronic structure families, including those where topological methods give R$^2$ = 0.52. This raises a question about the predictive limits of topological physics and its transformation into a wider study of bandstructures' and Fermi surfaces' geometries and relating them to the quantum geometry theory of a more general metric of eigenstates, opening horizon for the prediction of phenomena beyond topological understanding.

• High-energy logarithmic corrections to the QCD component of same-sign W-pair production

  Jeppe R. Andersen, Bertrand Ducloué, Conor Elrick, Andreas Maier, Graeme Nail, Jennifer M. Smillie

  SciPost Phys. Proc. 8, 129 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We describe the calculation of the QCD contribution to same-sign $W$-pair production, $pp\to e^\pm \nu_e \mu^\pm \nu_\mu jj$, resumming all contributions scaling as $\alpha_W^4 \alpha_s^{2+k}\log^k(\hat s/p_\perp^2)$ [arXiv:2107.06818]. These leading logarithmic contributions are enhanced by typical cuts used for Vector Boson Scattering (VBS) studies. We show that while the cross sections are little affected by these corrections, other more exclusive observables relevant for experimental studies are affected more significantly.

• Muon puzzle in inclined muon bundles detected by NEVOD-DECOR

  A. G. Bogdanov, N. S. Barbashina, S. S. Khokhlov, V. V. Kindin, R. P. Kokoulin, K. G. Kompaniets, A. Y. Konovalova, G. Mannocchi, A. A. Petrukhin, V. V. Shutenko, G. Trinchero, V. S. Vorobev, I. I. Yashin, E. A. Yurina, E. A. Zadeba

  SciPost Phys. Proc. 13, 003 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The data of cosmic ray NEVOD-DECOR experiment on the investigation of inclined muon bundles for a long time period (May 2012 - March 2021) are presented. The analysis showed that the observed intensity of muon bundles at primary cosmic ray energies of about 1 EeV and higher can be compatible with the expectation in frame of widely used hadron interaction models only under the assumption of an extremely heavy mass composition. This conclusion is consistent with data of several experiments on investigations of muon content in air showers, but contradicts the available fluorescence data on $X_{\text{max}}$ which favor a light mass composition at these energies. In order to clarify the nature of the "muon puzzle", investigations of the muon bundle energy deposit in the detector material were carried out. For the first time, experimental estimates of the average energy of muons in the bundles of inclined air showers initiated by primary particles with energies from 10 to 1000 PeV have been obtained.

• TAMBO: Searching for tau neutrinos in the Peruvian Andes

  William G. Thompson, on behalf of the TAMBO collaboration.

  SciPost Phys. Proc. 17, 021 (2025) · published 23 July 2025 | Toggle abstract · pdf

  TAMBO is a planned next-generation neutrino observatory sensitive to 1-100 PeV Earth-skimming tau neutrinos. This tau neutrino specificity will provide a high-purity sample of astrophysical neutrinos whose locations on the sky can then be used to improve the sensitivities of all-flavor neutrino observatories. The observatory will be located in a deep canyon and will comprise an array of water-Cherenkov and plastic scintillator air-shower detectors. In this proceeding, I will summarize the current status of the updated TAMBO simulation package, which is currently being used for detector optimization and reconstruction studies.

• Physics motivation and detector upgrades for the new era of the ATLAS experiment

  Jason Nielsen

  SciPost Phys. Proc. 8, 126 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The ATLAS experiment at CERN’s Large Hadron Collider (LHC) will be upgraded in two stages to prepare first for the Run 3 data-taking campaign, during which the integrated luminosity will roughly double, and then for the High-Luminosity LHC program with an ultimate integrated luminosity of up to 4 ab-1. These upgrades and high-statistics datasets will allow ATLAS to perform searches and precision measurements to constrain the Standard Model in yet-unexplored phase spaces and in the Higgs sector. This contribution summarizes the ATLAS detector upgrades and selected physics prospects for Run 3 and the HL-LHC.

• Clocking mechanism from a minimal spinning particle model

  Tobiasz Pietrzak, Łukasz Bratek

  SciPost Phys. Proc. 14, 042 (2023) · published 24 November 2023 | Toggle abstract · pdf

  The clock hypothesis plays an important role in the theory of relativity. To test this hypothesis, a mechanical model of an ideal clock is needed. Such a model should have the phase of its intrinsic periodic motion increasing linearly with the affine parameter of the clock's center of mass worldline. A class of relativistic rotators introduced by Staruszkiewicz in the context of an ideal clock is studied. A singularity in the inverse Legendre transform leading from the Hamiltonian to the Lagrangian leads to new possible Lagrangians characterized by fixed values of mass and spin. In free motion the rotators exhibit intrinsic motion with the speed of light and fixed frequency.

• Systematically constructing the likelihood for boosted $H\to gg$ decays

  Andrew J. Larkoski

  SciPost Phys. 18, 130 (2025) · published 17 April 2025 | Toggle abstract · pdf

  We study the binary discrimination problem of identification of boosted $H\to gg$ decays from massive QCD jets in a systematic expansion in the strong coupling. Though this decay mode of the Higgs is unlikely to be discovered at the LHC, we analytically demonstrate several features of the likelihood ratio for this problem through explicit analysis of signal and background matrix elements. Through leading-order, we prove that by imposing a constraint on the jet mass and measuring the energy fraction of the softer subjet an improvement of signal to background ratio that is independent of the kinematics of the jets at high boosts can be obtained, and is approximately equal to the inverse of the strong coupling evaluated at the Higgs mass. At next-to-leading order, we construct a powerful discrimination observable through a sort of anomaly detection approach by simply inverting the next-to-leading order $H\to gg$ matrix element with soft gluon emission, which is naturally infrared and collinear safe. Our analytic conclusions are validated in simulated data from all-purpose event generators and subsequent parton showering and demonstrate that the signal-to-background ratio can be improved by a factor of several hundred at high, but accessible, jet energies at the LHC.