Publications

Order by: publication date number of citations

• Particle Physics with the Pierre Auger Observatory

  Matias Perlin

  SciPost Phys. Proc. 8, 130 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The Pierre Auger Observatory is the largest extensive air shower detector. Based on a hybrid system, this experiment measures the longitudinal shower development and the particles at the ground. This detection system allows the extraction of the p-air cross-section at energies much higher than the ones accessible by current colliders. It is also possible to test hadronic interaction models using correlations between different air shower observables, like the depth of shower maximum and the muon number at the ground and their fluctuations. Thanks to the low energy extension of the Pierre Auger Observatory, the muon deficit in air shower simulations can be addressed over almost three decades at the highest energies.

  2 citations

• Phenomenological extraction of a universal TMD fragmentation function from single hadron production in $e^+ e^-$ annihilations

  M. Boglione, J.O. Gonzalez-Hernandez, A. Simonelli

  SciPost Phys. Proc. 8, 139 (2022) · published 14 July 2022 | Toggle abstract · pdf

  Factorizing the cross section for single hadron production in $e^+e^-$ annihilations, differential in $z_h$, $P_T$ and thrust, is a highly non trivial task. We have devised a factorization scheme that allows us to recast the $e^+e^- \to hX$ cross section in the convolution of a calculable hard coefficient and a universal Transverse Momentum Dependent (TMD) Fragmentation Function (FF). The predictions obtained from our NLO-LL perturbative computation, together with a simple ansatz to model the non-perturbative part of the TMD, are applied to the experimental measurements of the BELLE Collaboration for the phenomenological extraction of this process independent TMD FF.

  2 citations

• Integrability for Feynman integrals

  Florian Loebbert

  SciPost Phys. Proc. 14, 008 (2023) · published 23 November 2023 | Toggle abstract · pdf

  We give a brief overview of the Yangian symmetry of Feynman integrals. After a short introduction to the Yangian and integrability, we motivate the emergence of integrable structures for Feynman integrals via the fishnet limit of AdS/CFT. We discuss the resulting Yangian differential equations for massless fishnets in four dimensions as well as generalizations to massive propagators and generic dimensions. We also comment on the relation to momentum space conformal symmetry and on examples in dimensional regularization. Finally we sketch the recent application to fishnet integrals in two spacetime dimensions and the curious identification of Yangian invariants with period integrals of Calabi-Yau geometries.

  2 citations

• Subnucleon fluctuations in coherent and incoherent ultra-peripheral AA collisions at LHC and RHIC with the Sartre event generator

  Tobias Toll

  SciPost Phys. Proc. 8, 148 (2022) · published 14 July 2022 | Toggle abstract · pdf

  Sartre has been extensively used for describing photon-nuclei processes at the electron-ion collider (EIC) as well as ultra-peripheral collisions (UPC) at LHC and RHIC. Sartre is an event generator which implements the dipole model for DIS, and models the transverse geometry of the target nucleus or proton in coordinate space. It uses the Good-Walker mechanism for simulating fluctuations which contribute to the incoherent cross section for which the target breaks up after the interaction. With improved precision of UPC measurements in the last years, a detailed test of the dipole model has become possible, and Sartre's model was found lacking. In these proceedings we add subnucleon fluctuations to the nucleus and show that this is sufficient for describing the vast majority of the present measurements. We also find that for larger momentum transfers in the nucleus, which probes gluon fluctuations at higher resolution, the current complexity of the model may not suffice. Future measurements at the LHC, RHIC and especially the EIC has the potential to reveal these gluon vacuum fluctuations and glean novel insights into the self-interacting quantum field of QCD.

  2 citations

• On the unexpected fate of scientific ideas: An archeology of the Carroll group

  Jean-Marc Lévy-Leblond

  SciPost Phys. Proc. 14, 006 (2023) · published 23 November 2023 | Toggle abstract · pdf

  In 1965, I published a paper, exhibiting a hitherto unknown limit of the Lorentz group, which I christened "Carroll group" due to its seemingly paradoxical physical contents. Since I saw it as more curious than relevant, I published it in French in a journal somewhat afar from the mainstream of theoretical physics at that time. It was most gratifying to witness the quite unexpected favour this paper started to enjoy half a century later, so much that a so-called "Carrollian physics" is now developing, with applications in various domains of forefront theoretical physics, such as quantum gravitation, supersymmetry, string theory, etc. I offer this narrative as an example of the very diverse time scales with which scientific ideas may develop — or not.

  2 citations

• Recent results of laser spectroscopy experiments of pionic helium atoms at PSI

  M. Hori, H. Aghai-Khozani, A. S\'ot\'er, A. Dax, D. Barna

  SciPost Phys. Proc. 5, 026 (2021) · published 6 September 2021 | Toggle abstract · pdf

  A review of a recent experiment carried out at PSI involving laser spectroscopy of metastable pionic helium ($\pi{\rm ^4He}^+\equiv\pi^{-}+{\rm ^4He}^{2+}+e^-$) atoms is presented. An infrared transition $(n,\ell)=(17,16)$$\rightarrow$$(17,15)$ at a resonance frequency of $\nu\approx 183760$ GHz was detected.

  2 citations

• The eikonal model of reactions involving exotic nuclei; Roy Glauber's legacy in today's nuclear physics

  Pierre Capel

  SciPost Phys. Proc. 3, 017 (2020) · published 25 February 2020 | Toggle abstract · pdf

  In this contribution, the eikonal approximation developed by Roy Glauber to describe high-energy quantum collisions is presented. This approximation has been-and still is-extensively used to analyse reaction measurements performed to study the structure of nuclei far from stability. This presentation focuses more particularly on the application of the eikonal approximation to the study of halo nuclei in modern nuclear physics. To emphasise Roy Glauber's legacy in today's nuclear physics, recent extensions of this model are reviewed.

  2 citations

• Impact of heavy-quark production measurements in the CT18 global QCD analysis of PDFs

  Marco Guzzi, Pavel Nadolsky, Keping Xie

  SciPost Phys. Proc. 8, 164 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We discuss the impact of heavy-flavor production measurements in semi-inclusive deep inelastic scattering at HERA on the CTEQ-TEA PDFs. In particular, we study the impact of the latest charm and bottom production measurements from the H1 and ZEUS collaborations on the gluon, and the interplay of these measurements with the data ensemble of the recent CT18 global QCD analysis.

  2 citations

• Study of deuteron-proton backward elastic scattering at intermediate energies

  Nadezhda Ladygina

  SciPost Phys. Proc. 3, 053 (2020) · published 27 February 2020 | Toggle abstract · pdf

  We study deuteron- proton elastic scattering in the deuteron energy range between 500 MeV and 2~GeV at the cms scattering angle $\theta^*\ge 140^\circ$. The reaction is considered in the relativistic multiple scattering expansion framework. The four reaction mechanisms are included into consideration: one-nucleon exchange, single scattering, double scattering, and the term corresponding to the delta excitation in the intermediate state. The model is applied to describe the angular dependence of the differential cross section at the deuteron energies of between 880 and 1300 MeV. Also the energy dependence of the differential cross section and polarisation observables such as tensor analyzing power $T_{20}$ and polarization transfer from the deuteron to proton $\varkappa$ are considered at the scattering angle equal to 180$^\circ$. Contributions of the different reaction mechanisms into the reaction amplitude are demonstrated in comparison with the existing experimental data.

  2 citations

• SINDRUM II

  A. van der Schaaf

  SciPost Phys. Proc. 5, 008 (2021) · published 6 September 2021 | Toggle abstract · pdf

  In 1987 a collaboration including ETHZ - UZH - PSI - RWTH Aachen - Univ. Tbilisi proposed a new search for μe conversion in muonic atoms. The SINDRUM II spectrometer came into operation in the PSI μE1 area in 1989, but a dedicated beam line was delayed until 1998 by technical setbacks.

  2 citations