Publications

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Dynamical correlation functions in the Ising field theory

István Csépányi, Márton Kormos

SciPost Phys. 17, 162 (2024) · published 10 December 2024 | · pdf

We study finite temperature dynamical correlation functions of the magnetization operator in the one-dimensional Ising quantum field theory. Our approach is based on a finite temperature form factor series and on a Fredholm determinant representation of the correlators. While for space-like separations the Fredholm determinant can be efficiently evaluated numerically, for the time-like region it has convergence issues inherited from the form factor series. We develop a method to compute the correlation functions at time-like separations based on the analytic continuation of the space-time coordinates to complex values. Using this numerical technique, we explore all space-time and temperature regimes in both the ordered and disordered phases including short, large, and near-light-cone separations at low and high temperatures. We confirm the existing analytic predictions for the asymptotic behavior of the correlations except in the case of space-like correlations in the paramagnetic phase. For this case we derive a new closed form expression for the correlation length that has some unusual properties: it is a non-analytic function of both the space-time direction and the temperature, and its temperature dependence is non-monotonic.
Precise quantum-geometric electronic properties from first principles

José Luís Martins, Carlos Loia Reis, Ivo Souza

SciPost Phys. 19, 109 (2025) · published 24 October 2025 | · pdf

The calculation of quantum-geometric properties of Bloch electrons – Berry curvature, quantum metric, orbital magnetic moment and effective mass – was implemented in a pseudopotential plane-wave code. The starting point was the first derivative of the periodic part of the wavefunction $\psi_{k}(r)$ with respect to wavevector $k$. This was evaluated with perturbation theory by solving a Sternheimer equation. Comparison of effective masses obtained from perturbation theory for silicon and gallium arsenide with carefully-converged numerical second derivatives of band energies confirmed the high precision of the method. Calculations of quantum-geometric quantities for gapped graphene were performed by adding a bespoke symmetry-breaking potential to first-principles graphene. As the two bands near the opened gap are reasonably isolated, the results could be compared with those obtained from an analytical two-band model, allowing to assess the strengths and limitations of such widely-used models. The final application was trigonal tellurium, where some quantum-geometric quantities flip sign with chirality.
Achieving quantum advantage in a search for a violations of the Goldbach conjecture, with driven atoms in tailored potentials

Oleksandr V. Marchukov, Andrea Trombettoni, Giuseppe Mussardo, Maxim Olshanii

SciPost Phys. Core 8, 074 (2025) · published 28 October 2025 | · pdf

The famous Goldbach conjecture states that any even natural number $N$ greater than $2$ can be written as the sum of two prime numbers $p^{\text{(I)}}$ and $p^{\text{(II)}}$. In this article we propose a quantum analogue device that solves the following problem: given a small prime $p^{\text{(I)}}$, identify a member $N$ of a $\mathcal{N}$-strong set even numbers for which $N-p^{\text{(I)}}$ is also a prime. A table of suitable large primes $p^{\text{(II)}}$ is assumed to be known a priori. The device realizes the Grover quantum search protocol and as such ensures a $\sqrt{\mathcal{N}}$ quantum advantage. Our numerical example involves a set of 51 even numbers just above the highest even classical-numerically explored so far [T. O. e Silva, S. Herzog, and S. Pardi, Mathematics of Computation 83, 2033 (2013)]. For a given small prime number $p^{\text{(I)}}=223$, it took our quantum algorithm 5 steps to identify the number $N=4× 10^{18}+14$ as featuring a Goldbach partition involving $223$ and another prime, namely $p^{\text{(II)}}=4× 10^{18}-239$. Currently, our algorithm limits the number of evens to be tested simultaneously to $\mathcal{N} \sim \ln(N)$: larger samples will typically contain more than one even that can be partitioned with the help of a given $p^{\text{(I)}}$, thus leading to a departure from the Grover paradigm.
Recent results from heavy ion collisions at LHCb

Óscar Boente García

SciPost Phys. Proc. 8, 007 (2022) · published 11 July 2022 | · pdf

LHCb is a fully instrumented spectrometer covering the forward rapidity region at the LHC, which provides unique access to the small Bjorken-x region inside the nucleus. In this contribution, a selection of recent results from the LHCb heavy-ion program are presented, including a measurement of charged hadron production in proton-proton (pp) and proton-lead (pPb) collisions, chic2/chic1 production in pPb collisions, and coherent J/psi production in peripheral and ultra-peripheral PbPb collisions. Comparisons with calculations and effects from the nuclear PDFs and dense QCD medium are discussed.
Gluon saturation in proton and its contribution to single inclusive soft gluon production in high energy proton-nucleus collisions

Ming Li

SciPost Phys. Proc. 8, 162 (2022) · published 14 July 2022 | · pdf

The leading order single inclusive soft gluon production in high energy proton-nucleus (pA) collisions has been studied by various approaches for more than two decades. The first correction due to the gluon saturation in proton was analytically attempted recently through a diagrammatic approach in which only partial results were obtained. An important feature of the first saturation correction is that it includes both initial state and final state interactions. In this paper, we present the complete result derived from the Color Glass Condensate framework. Our approach is to analytically solve the classical Yang-Mills equations in the dilute-dense regime and then use the Lehmann-Symanzik-Zimmermann (LSZ) reduction formula to obtain gluon production from classical gluon fields.
Annihilating dark matter search with 12 years of Fermi LAT data in nearby galaxy clusters

Charles Thorpe-Morgan, D. Malyshev, C.-A. Stegen, Andrea Santangelo, J. Jochum

SciPost Phys. Proc. 12, 071 (2023) · published 10 July 2023 | · pdf

Galaxy clusters contain an abundance of dark matter making them attractive laboratories for indirect DM searches. This work details a search for signals of pair annihilation from WIMP dark matter in the GeV gamma ray regime. We perform this search in five low $z$ and high galactic latitude galaxy clusters (Centaurus, Coma, Virgo, Perseus and Fornax); using nearly 12 years of Fermi/LAT data. Through the non-detection of this characteristic signal, we derive constraints on the annihilation cross-section of DM pair annihilation into the $b\overline{b}$, $W^+W^-$ and $\gamma\gamma$ channels. The limits obtained are of a comparable magnitude to those of recently derived from Fermi/LAT observations of dwarf spheroidal galaxies.
Recent results from reactor antineutrino experiments

Hyunkwan Seo

SciPost Phys. Proc. 1, 027 (2019) · published 20 February 2019 | · pdf

The smallest neutrino mixing angle $\theta_{13}$ has been successfully measured by the disappearance of reactor antineutrinos at RENO, Daya Bay, and Double Chooz. The oscillation frequency is also measured based on energy and baseline dependent disappearance probability of reactor antineutrinos. Recent results fi nd a variation in the observed reactor antineutrino flux as a function of the reactor fuel evolution. We report more precisely measured values of $\theta_{13}$ and $\Delta m^2_{ee}$ and results on the evolution of observed reactor antineutrino yield and spectrum.
Measuring single-top-associated Higgs production at the HL-LHC

Henning Bahl

SciPost Phys. Proc. 8, 010 (2022) · published 11 July 2022 | · 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.
On the generalized Komar charge of Kaluza-Klein theories and higher-form symmetries

Gabriele Barbagallo, José Luis V. Cerdeira, Carmen Gómez-Fayrén, Patrick Meessen, Tomás Ortín

SciPost Phys. Core 8, 077 (2025) · published 4 November 2025 | · pdf

The generalized Komar $(d-2)$-form charge can be modified by the addition of any other on-shell closed (conserved) $(d-2)$-form charge. We show that, with Kaluza–Klein boundary conditions, one has to add a charge related to the higher-form symmetry identified in Ref. [C. Gomez-Fayren et al., SciPost Phys. Core 8, 010 (2025)] to the naive Komar charge of pure 5-dimensional gravity to obtain a conserved charge whose integral at spatial infinity gives the mass. The new term also contains the contribution of the Kaluza–Klein monopole charge leading to electric-magnetic duality invariance.
Engineering of anyons on M5-probes via flux quantization

Hisham Sati, Urs Schreiber

SciPost Phys. Lect. Notes 107 (2025) · published 4 November 2025 | · pdf

These extended lecture notes survey a novel derivation of anyonic topological order (as seen in fractional quantum Hall systems) on single magnetized M5-branes probing Seifert orbi-singularities ("geometric engineering" of anyons), which we motivate from fundamental open problems in the field of quantum computing. The rigorous construction is non-Lagrangian and non-perturbative, based on previously neglected global completion of the M5-brane's tensor field by flux-quantization consistent with its non-linear self-duality and its twisting by the bulk C-field. This exists only in little-studied non-abelian generalized cohomology theories, notably in a twisted equivariant (and "twistorial") form of unstable Cohomotopy ("Hypothesis H"). As a result, topological quantum observables form Pontrjagin homology algebras of mapping spaces from the orbi-fixed worldvolume into a classifying 2-sphere. Remarkably, results from algebraic topology imply from this the quantum observables and modular functor of abelian Chern-Simons theory, as well as braid group actions on defect anyons of the kind envisioned as hardware for topologically protected quantum gates.

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