Publications

Order by: publication date number of citations

• Correlations between azimuthal asymmetries and multiplicity and mean transverse momentum in small collisions systems in the CGC

  Tolga Altinoluk, Néstor Armesto, Alex Kovner, Michael Lublinsky, Vladimir V. Skokov

  SciPost Phys. Proc. 8, 051 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Considering a dilute-dense situation suitable for pA collisions, we compute in the Color Glass Condensate the correlation between azimuthal asymmetries, specifically the squared second Fourier coefficient $v_2^2$, and the total multiplicity in the event. We also analyse the correlation between $v_2^2$ and the mean squared transverse momentum of particles in the event. In both cases, we find that the correlations are generally very small, consistent with the observations. We also note an interesting sharp change in the value of $v_2^2$ and its correlations as a function of the width of the transverse momentum bin, related with a change of the dominance of Bose and HBT quantum correlations.

• The Compton Amplitude, lattice QCD and the Feynman-Hellmann approach

  K.U. Can, A. Hannaford-Gunn, R. Horsley, Y. Nakamura, H. Perlt, P.E.L. Rakow, E. Sankey, G. Schierholz, H. Stuben, R.D. Young, J.M. Zanotti

  SciPost Phys. Proc. 6, 003 (2022) · published 31 May 2022 | Toggle abstract · pdf

  A major objective of lattice QCD is the computation of hadronic matrix elements. The standard method is to use three-point and four-point correlation functions. An alternative approach, requiring only the computation of two-point correlation functions is to use the Feynman-Hellmann theorem. In this talk we develop this method up to second order in perturbation theory, in a context appropriate for lattice QCD. This encompasses the Compton Amplitude (which forms the basis for deep inelastic scattering) and hadron scattering. Some numerical results are presented showing results indicating what this approach might achieve.

• Dynamic hysteresis across a dissipative multi-mode phase transition

  Marvin Röhrle, Jens Benary, Erik Bernhart, Herwig Ott

  SciPost Phys. 16, 158 (2024) · published 28 June 2024 | Toggle abstract · pdf

  Dissipative phase transitions are characteristic features in open quantum systems. Key signatures are the dynamical switching between different states in the vicinity of the phase transition and the appearance of hysteresis. Here, we experimentally study dynamic sweeps across a first order dissipative phase transition in a multi-mode driven-dissipative system. In contrast to previous studies, we perform sweeps of the dissipation strength instead of the driving strength. We extract exponents for the scaling of the hysteresis area in dependence of the sweep time and study the $g^{(2)}(0)$ correlations, which show non-trivial behavior. By changing the temperature of the system we investigate the importance of coherently pumping the system. We compare our results to numerical calculations done for a single mode variant of the system, and find surprisingly good agreement. Furthermore, we identify and discuss the differences between a scan of the dissipation strength and a scan of the driving strength.

• Transverse spin asymmetries for inclusive $\rho^0$ production in SIDIS at COMPASS

  A. Kerbizi

  SciPost Phys. Proc. 8, 146 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The production of vector mesons in SIDIS is a particularly interesting channel to study the polarized fragmentation and related phenomena. Preliminary COMPASS results for the first measurement of inclusive $\rho^0$ Collins and Sivers transverse-spin asymmetries are presented here for the first time. The analysis is based on the data-set collected by COMPASS in $2010$ using a $160\, \rm{GeV}/c$ $\mu^+$ beam and a transversely polarized $NH_3$ target. The asymmetries are extracted as function of Bjorken-$x$, of the total transverse momentum of the oppositely charged hadron pair and of the fraction of available energy $z$ carried by the pair. Indications for positive Collins and Sivers asymmetries are obtained as expected from models.

• Transversity through Dihadron: a constrained fit

  Aurore Courtoy

  SciPost Phys. Proc. 8, 049 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We present a study of the valence transversity PDF obtained through a constrained fit. The effects of the constraints on the uncertainties of the PDF are explored. We show that the resulting isovector tensor charge is largely undetermined and, hence, compatible with all lattice evaluations.

• Probing gluon density fluctuations at large momentum transfer $|t|$ at HERA

  Arjun Kumar

  SciPost Phys. Proc. 8, 166 (2022) · published 14 July 2022 | Toggle abstract · pdf

  The information on the gluonic structure and its fluctuations is captured by the differential $|t|$ spectrum in diffractive events. The incoherent cross-section is sensitive to the fluctuations in the target wavefunction in such events. We investigate the incoherent $ep$ cross-section in $J/\psi$ photoproduction using the impact-parameter dependent dipole model. The spatial gluonic structure is modelled as hotspots of gluon density having substructure where this substructure is modelled as hotspots within hotspots. We find that three levels of the substructure provide a good description of all the data, available up to $|t|=30~$GeV$^2$. We investigate these fluctuations in both the saturated and non-saturated dipole models and compare our predictions with the HERA Data.

• Characterizing far from equilibrium states of the one-dimensional nonlinear Schrödinger equation

  Abhik Kumar Saha, Romain Dubessy

  SciPost Phys. Core 8, 028 (2025) · published 6 March 2025 | Toggle abstract · pdf

  We use the mathematical toolbox of the inverse scattering transform to study quantita- tively the number of solitons in far from equilibrium one-dimensional systems described by the defocusing nonlinear Schrödinger equation. We present a simple method to iden- tify the discrete eigenvalues in the Lax spectrum and provide a extensive benchmark of its efficiency. Our method can be applied in principle to all physical systems described by the defocusing nonlinear Schrödinger equation and allows to identify the solitons velocity distribution in numerical simulations and possibly experiments.

• Recent jet and jet substructure measurements at the LHC, and ML based tagging

  Meena Meena

  SciPost Phys. Proc. 10, 022 (2022) · published 10 August 2022 | Toggle abstract · pdf

  Recent jet and jet substructure measurements at the LHC, and of machine-learning-based tagging techniques are presented using proton-proton collision data collected by the ATLAS and CMS experiments at CERN's Large Hadron Collider. These measurements are crucial for precise tests of electroweak and pQCD calculations and searches for physics beyond the Standard Model. The measurements are compared with several Monte Carlo event generator predictions which provide valuable input to the tuning of perturbative and non-perturbative models and to constraining model parameters of advanced parton-shower Monte Carlo programs.

• Difference equations: From Berry connections to the Coulomb branch

  Andrea E. V. Ferrari, Daniel Zhang

  SciPost Phys. 18, 045 (2025) · published 5 February 2025 | Toggle abstract · pdf

  In recent work, we demonstrated that a spectral variety for the Berry connection of a 2d $\mathcal{N}=(2,2)$ GLSM with Kähler vacuum moduli space $X$ and Abelian flavour symmetry is the support of a sheaf induced by a certain action on the equivariant quantum cohomology of $X$. This action could be quantised to first-order matrix difference equations obeyed by brane amplitudes, and by taking the conformal limit, vortex partition functions. In this article, we elucidate how some of these results may be recovered from a 3d perspective, by placing the 2d theory at a boundary and gauging the flavour symmetry via a bulk A-twisted 3d $\mathcal{N}=4$ gauge theory (a sandwich construction). We interpret the above action as that of the bulk Coulomb branch algebra on boundary twisted chiral operators. This relates our work to recent constructions of actions of Coulomb branch algebras on quantum equivariant cohomology, providing a novel correspondence between these actions and spectral data of generalised periodic monopoles. The effective IR description of the 2d theory in terms of a twisted superpotential allows for explicit computations of these actions, which we demonstrate for Abelian GLSMs.

• 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.