Publications

Order by: publication date number of citations

• Anomalous coupling studies with intact protons at the LHC

  Cristophe Royon

  SciPost Phys. Proc. 15, 029 (2024) · published 3 April 2024 | Toggle abstract · pdf

  We describe the reaches on quartic $\gamma \gamma \gamma \gamma$, $\gamma \gamma WW$, $\gamma \gamma ZZ$, $\gamma \gamma \gamma Z$, $\gamma \gamma t \bar{t}$ anomalous couplings at the LHC using intact protons in the final state measured in AFP in ATLAS or PPS in CMS-TOTEM.

  1 citation

• Codebase release 2.0 for sauce

  Caleb Marshall

  SciPost Phys. Codebases 37-r2.0 (2024) · published 6 November 2024 | Toggle abstract · src

  Low energy nuclear physics experiments are transitioning towards fully digital data acquisition systems. Realizing the gains in flexibility afforded by these systems relies on equally flexible data reduction techniques. In this paper, methods utilizing data frames and in-memory techniques to work with data, including data from self-triggering, digital data acquisition systems, are discussed within the context of a Python package, sauce. It is shown that data frame operations can encompass common analysis needs and allow interactive data analysis. Two event building techniques, dubbed referenced and referenceless event building, are shown to provide a means to transform raw list mode data into correlated multi-detector events. These techniques are demonstrated in the analysis of two example data sets.

  1 citation

• Solvable models for 2+1D quantum critical points: Loop soups of 1+1D conformal field theories

  Amin Moharramipour, Dan Sehayek, Thomas Scaffidi

  SciPost Phys. 16, 061 (2024) · published 28 February 2024 | Toggle abstract · pdf

  We construct a class of solvable models for 2+1D quantum critical points by attaching 1+1D conformal field theories (CFTs) to fluctuating domain walls forming a "loop soup". Specifically, our local Hamiltonian attaches gapless spin chains to the domain walls of a triangular lattice Ising antiferromagnet. The macroscopic degeneracy between antiferromagnetic configurations is split by the Casimir energy of each decorating CFT, which is usually negative and thus favors a short loop phase with a finite gap. However, we found a set of 1D CFT Hamiltonians for which the Casimir energy is effectively positive, making it favorable for domain walls to coalesce into a single "snake" which is macroscopically long and thus hosts a CFT with a vanishing gap. The snake configurations are geometrical objects also known as fully-packed self-avoiding walks or Hamiltonian walks which are described by an $\mathrm{O}$(n=0) loop ensemble with a non-unitary 2+0D CFT description. Combining this description with the 1+1D decoration CFT, we obtain a 2+1D theory with unusual critical exponents and entanglement properties. Regarding the latter, we show that the log contributions from the decoration CFTs conspire with the spatial distribution of loops crossing the entanglement cut to generate a "non-local area law". Our predictions are verified by Monte Carlo simulations.

  1 citation

• Simulation of the 1d XY model on a quantum computer

  Marc Farreras, Alba Cervera-Lierta

  SciPost Phys. Lect. Notes 95 (2025) · published 11 June 2025 | Toggle abstract · pdf

  The field of quantum computing has grown fast in recent years, both in theoretical advancements and the practical construction of quantum computers. These computers were initially proposed, among other reasons, to efficiently simulate and comprehend the complexities of quantum physics. In this paper, we present a comprehensive scheme for the exact simulation of the 1-D XY model on a quantum computer. We successfully diagonalize the proposed Hamiltonian, enabling access to the complete energy spectrum. Furthermore, we propose a novel approach to design a quantum circuit to perform exact time evolution. Among all the possibilities this opens, we compute the ground and excited state energies for the symmetric XY model with spin chains of $n=4$ and $n=8$ spins. Further, we calculate the expected value of transverse magnetization for the ground state in the transverse Ising model. Both studies allow the observation of a quantum phase transition from an antiferromagnetic to a paramagnetic state. Additionally, we have simulated the time evolution of the state all spins up in the transverse Ising model. The scalability and high performance of our algorithm make it an ideal candidate for benchmarking purposes, while also laying the foundation for simulating other integrable models on quantum computers.

  1 citation

• Radiation statistics of a degenerate parametric oscillator at threshold

  Fabian Hassler, Steven Kim, Lisa Arndt

  SciPost Phys. 14, 156 (2023) · published 15 June 2023 | Toggle abstract · pdf

  As a function of the driving strength, a degenerate parametric oscillator exhibits an instability at which spontaneous oscillations occur. Close to threshold, both the nonlinearity as well as fluctuations are vital to the accurate description of the dynamics. We study the statistics of the adiation that is emitted by the degenerate parametric oscillator at threshold. For a weak nonlinearity, we can employ a quasiclassical description. We identify a universal Liouvillian that captures the relevant long-time dynamics for large photon-numbers. We find that the cumulants obey a universal power-law scaling as a function of the nonlinearity. The Fano factor shows a maximum close, but not coinciding, with the threshold. Moreover, we predict a certain ratio of the first three cumulants to be independent of the microscopic details of the system and connect the results to experimental platforms.

  1 citation

• TAIGA - An advanced hybrid detector complex for astroparticle physics and high energy gamma-ray astronomy

  N. M. Budnev, I. Astapov, P. Bezyazeekov, E. Bonvech, A. Borodin, A. Bulan, D. Chernov, A. Chiavassa, A. Dyachok, A. Gafarov, A. Garmash, V. Grebenyuk, E. Gress, O. Gress, T. Gress, A. Grinyuk, O. Grishin, A. D. Ivanova, A. L. Ivanova, N. Kalmykov, V. Kindin, S. Kiryuhin, R. Kokoulin, K. Kompaniets, E. Korosteleva, V. Kozhin, E. Kravchenko, A. Kryukov, L. Kuzmichev, A. Lagutin, M. Lavrova, Y. Lemeshev, B. Lubsandorzhiev, N. Lubsandorzhiev, A. Lukanov, D. Lukyantsev, S. Malakhov, R. Mirgazov, R. Monkhoev, E. Osipova, A. Pakhorukov, L. Pankov, A. Pan, A. Panov, A. Petrukhin, I. Poddubnyi, D. Podgrudkov, V. Ponomareva, E. Popova, E. Postnikov, V. Prosin, V. Ptuskin, A. Pushnin, R. Raikin, A. Razumov, G. Rubtsov, E. Ryabov, V. Samoliga, A. Satyshev, A. Silaev, A. Silaev, A. Sidorenkov, A. Skurikhin, A. Sokolov, L. Sveshnikova, V. Tabolenko, L. Tkachev, A. Tanaev, M. Ternovoy, R. Togoo, N. Ushakov, A. Vaidyanathan, P. Volchugov, N. Volkov, D. Voronin, A. Zagorodnikov, D. Zhurov, I. Yashin

  SciPost Phys. Proc. 13, 027 (2023) · published 29 September 2023 | Toggle abstract · pdf

  The physical motivations, present status, main results in study of cosmic rays and in the field of gamma-ray astronomy as well future plans of the TAIGA-1 (Tunka Advanced Instrument for cosmic ray physics and Gamma Astronomy) project are presented. The TAIGA observatory addresses ground-based gamma-ray astronomy and astroparticle physics at energies from a few TeV to several PeV, as well as cosmic ray physics from 100 TeV to several EeV. The pilot TAIGA-1 complex is located in the Tunka valley, 50 km west from the southern tip of the lake Baikal.

  1 citation

• Codebase release r1.4 for CoVVVR

  Prasanth Shyamsundar, Jacob L. Scott, Stephen Mrenna, Konstantin T. Matchev, Kyoungchul Kong

  SciPost Phys. Codebases 28-r1.4 (2024) · published 4 March 2024 | Toggle abstract · src

  Monte Carlo (MC) integration is an important calculational technique in the physical sciences. Practical considerations require that the calculations are performed as accurately as possible for a given set of computational resources. To improve the accuracy of MC integration, a number of useful variance reduction algorithms have been developed, including importance sampling and control variates. In this work, we demonstrate how these two methods can be applied simultaneously, thus combining their benefits. We provide a python wrapper, named CoVVVR, which implements our approach in the VEGAS program. The improvements are quantified with several benchmark examples from the literature.

  1 citation

• Universal Properties of Anisotropic Dipolar Bosons in Two Dimensions

  J. Sánchez-Baena, L. A. Peña Ardila, G. Astrakharchik, F. Mazzanti

  SciPost Phys. 13, 031 (2022) · published 25 August 2022 | Toggle abstract · pdf

  The energy of ultra-dilute quantum many-body systems is known to exhibit a universal dependence on the gas parameter $x=n a_0^d$, with $n$ the density, $d$ the dimensionality of the space ($d=1,2,3$) and $a_0$ the $s$-wave scattering length. The universal regime typically extends up to $x\approx 0.001$, while at larger values specific details of the interaction start to be relevant and different model potentials lead to different results. Dipolar systems are peculiar in this regard since the anisotropy of the interaction makes $a_0$ depend on the polarization angle $\alpha$, so different combinations of $n$ and $\alpha$ can lead to the same value of the gas parameter $x$. In this work we analyze the scaling properties of dipolar bosons in two dimensions as a function of the density and polarization dependent scattering length up to very large values of the gas parameter $x$. Using Quantum Monte Carlo (QMC) methods we study the energy and the main structural and coherence properties of the ground state of a gas of dipolar bosons by varying the density and scattering length for fixed gas parameter. We find that the dipolar interaction shows relevant scaling laws up to unusually large values of $x$ that hold almost to the boundaries in the phase diagram where a transition to a stripe phase takes place.

  1 citation

• Implementing Transverse Momentum Dependent splitting functions in Parton Branching evolution equations

  Lissa Keersmaekers

  SciPost Phys. Proc. 8, 127 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The Parton Branching (PB) approach describes the evolution of transverse momentum dependent (TMD) parton densities. We propose to extend the PB method by including TMD splitting functions, instead of the DGLAP splitting functions which assume strong ordering in transverse momentum. We present the evolution equations and their numerical solution, which is the first Monte Carlo implementation including TMD splitting functions.

  1 citation

• Variational solution of the superconducting Anderson impurity model and the band-edge singularity phenomena

  Teodor Iličin, Rok Žitko

  SciPost Phys. 19, 006 (2025) · published 2 July 2025 | Toggle abstract · pdf

  We propose a set of variational wavefunctions for the sub-gap spin-doublet and spin-singlet eigenstates of the particle-hole symmetric superconducting Anderson impurity model. The wavefunctions include up to two Bogoliubov quasiparticles in the continuum which is necessary to correctly capture the weak-coupling asymptotics in all parameter regimes. The eigenvalue problems reduce to solving transcendental equations. We investigate how the lowest singlet state evolves with increasing charge repulsion $U$, transitioning from a proximitized state (a superposition of empty and doubly occupied impurity orbitals, corresponding to an Andreev bound state) to a local moment that is Kondo screened by Bogoliubov quasiparticles (Yu-Shiba-Rusinov state). This change occurs for $U = 2\Delta$, where $\Delta$ is the BCS gap. At this point, the band-edge effects make the eigenenergy scale in a singular way as $\Gamma^{2/3}$, where $\Gamma$ is the hybridization strength. Away from this special point, regular $\Gamma$-linear behavior is recovered, but only for $\Gamma ≲ (U/2-\Delta)^2/\Delta$. The singular behavior thus extends over a broad range of parameters, including those relevant for some quantum devices in current use. The singular state is an equal-superposition state with maximal fluctuations between the local impurity charge configurations. Accurately capturing the band-edge singularity requires a continuum model, and it cannot be correctly described by discrete (truncated) models such as the zero-bandwidth approximation or the superconducting atomic limit. We determine the region of parameter space where the second spin-singlet state exists: in addition to the whole $U<2\Delta$ ABS region, it also includes a small part of the $U>2\Delta$ YSR region for finite values of $\Gamma$, as long as some ABS wavefunction component is admixed.

  1 citation