Publications

Order by: publication date number of citations

• Probing proton PDFs at high x with LHCb

  Thomas Boettcher

  SciPost Phys. Proc. 8, 093 (2022) · published 13 July 2022 | Toggle abstract · pdf

  LHCb is a forward spectrometer at the LHC covering the pseudorapidity region 2<$\eta$<5. Because of this forward coverage, LHCb can probe the proton parton distribution functions (PDFs) in previously unexplored kinematic regimes, in particular at very high and low Bjorken-x. This contribution presents LHCb measurements that can be used to constrain the proton PDFs, with a focus on the high-x and high-$Q^2$ regime.

• Bethe Ansatz inside Calogero-Sutherland models

  Gwenaël Ferrando, Jules Lamers, Fedor Levkovich-Maslyuk, Didina Serban

  SciPost Phys. 18, 035 (2025) · published 28 January 2025 | Toggle abstract · pdf

  We study the trigonometric quantum spin-Calogero–Sutherland model, and the Haldane–Shastry spin chain as a special case, using a Bethe-Ansatz analysis. We harness the model's Yangian symmetry to import the standard tools of integrability for Heisenberg spin chains into the world of integrable long-range models with spins. From the transfer matrix with a diagonal twist we construct Heisenberg-style symmetries (Bethe algebra) that refine the usual hierarchy of commuting Hamiltonians (quantum determinant) of the spin-Calogero–Sutherland model. We compute the first few of these new conserved charges explicitly, and diagonalise them by Bethe Ansatz inside each irreducible Yangian representation. This yields a new eigenbasis for the spin-Calogero–Sutherland model that generalises the Yangian Gelfand–Tsetlin basis of Takemura–Uglov. The Bethe-Ansatz analysis involves non-generic values of the inhomogeneities. Our review of the inhomogeneous Heisenberg XXX chain, with special attention to how the Bethe Ansatz works in the presence of fusion, may be of independent interest.

• Studies of $b$-hadrons and quarkonia at LHCb

  Zhiyu Xiang

  SciPost Phys. Proc. 8, 092 (2022) · published 13 July 2022 | Toggle abstract · pdf

  LHCb has productive studies of quarkonia and $b$-hadrons which provide essential inputs to study quantum chromodynamics (QCD). In this proceeding, seven recent results are reported: the observation of a new excited $\Xi_b^0$ resonance in $\Xi_b^- \pi^+$ final states, the new excited $B_s^0$ state is observed in $B^+ K^-$ mass spectrum, the first observation of suppressed semileptonic $B_s^0 \rightarrow K^- \mu^+ \nu_{\mu}$ decay, the first observation of the decay $B^0 \rightarrow D^0 \bar{D}^0 K^+ \pi^-$, the first observation of the Cabibbo-suppressed decay $\Lambda_b^0 \rightarrow \chi_{c1} p \pi^-$, the first observation of $\Lambda_b^0 \rightarrow \Lambda_c^+ K^+ K^- \pi^-$ decay, and end this report with the first search for the doubly heavy baryon $\Omega_{bc}^{0}$ and a search for $\Xi_{bc}^0$ baryon.

• Ionization efficiency at sub-keV energies for crystals and noble liquids

  Youssef Sarkis, Alexis A. Aguilar-Arevalo, Juan Carlos D'Olivo

  SciPost Phys. Proc. 12, 008 (2023) · published 3 July 2023 | Toggle abstract · pdf

  We study the ionization and light yields produced by nuclear recoils at low energies in pure crystals and noble liquids in the context of Lindhard's integral equation, incorporating the effects of binding energy, improved modeling of the electronic stopping, and electronic straggling. We consider three different models for the electronic stopping power that incorporate Coulomb repulsion effects at low energies, and Bohr electronic stripping for high energies. Finally, we discuss possible new effects near threshold.

• Prospects for diffractive dijet photoproduction at the EIC

  V. Guzey, M. Klasen

  SciPost Phys. Proc. 8, 142 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We discuss the prospects of diffractive dijet photoproduction at the EIC to distinguish different fits of diffractive proton PDFs, different schemes of factorization breaking, to determine diffractive nuclear PDFs and pion PDFs from leading neutron production.

• 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.

• Measurement of low-energy Compton and neutron scattering in Si CCDs for dark matter searches

  Radomir Smida for the DAMIC-M Collaboration

  SciPost Phys. Proc. 12, 015 (2023) · published 3 July 2023 | Toggle abstract · pdf

  For optimal sensitivity to low-mass dark matter candidates experiments like DAMIC-M employ skipper charged-coupled devices (CCDs) with detection threshold of just a few ionization charges. Ionization signals from small-angle Compton scatters of environmental $\gamma$-rays, an important component of the background in dark matter searches, must thus be characterized down to $O$(10 eV) energy. Using a $^{241}$Am $\gamma$-ray source, we report a precise measurement of scattering on Si atomic shell electrons in a skipper CCD with single-electron resolution. Notable differences are observed between data and theoretical expectations in the L-shell energy region ($<$150 eV). We also present preliminary data from a skipper CCD exposed to low-energy neutrons ($<$24 keV) from a $^{124}$Sb$^9$Be photoneutron source, demonstrating a measurement of the nuclear recoil ionization efficiency in Si down to few ionization charges.

• Introduction to string theory

  Carlo Maccaferri, Fabio Marino, Beniamino Valsesia

  SciPost Phys. Lect. Notes 90 (2025) · published 29 January 2025 | Toggle abstract · pdf

  These are lecture notes of the introductory String Theory course held by one of the authors for the master program of Theoretical Physics at Turin University. The world-sheet approach to String Theory is pedagogically introduced in the framework of the bosonic string and of the superstring.

• 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.

• Limits to gauge coupling in the dark sector of super-heavy dark matter particles from the Pierre Auger Observatory data

  Olivier Deligny for the Pierre Auger Collaboration

  SciPost Phys. Proc. 13, 013 (2023) · published 28 September 2023 | Toggle abstract · pdf

  Assuming that the energy density of super-heavy particles matches that of dark matter observed today, tight constraints on the couplings governing the decay process are presented as a function of the particle mass. These constraints are obtained from the lack of signatures that would be suggestive of decaying super-heavy $X$ particles in the data of the Pierre Auger Observatory. In particular, instanton-induced decay processes allow us to derive a bound on the reduced coupling constant of gauge interactions in the dark sector: $\alpha_X \lesssim 0.09$, for $10^{9} \lesssim M_X/\mathrm{GeV} < 10^{19}$. Cosmological aspects for super-heavy dark matter production during the reheating epoch are discussed.