Publications

Order by: publication date number of citations

• Higher-order corrections to exclusive heavy vector meson production

  Tuomas Lappi, Heikki Mäntysaari, Jani Penttala

  SciPost Phys. Proc. 8, 133 (2022) · published 14 July 2022 | Toggle abstract · pdf

  We present results for higher-order corrections to exclusive $\mathrm{J}/\psi$ production. This includes the first relativistic correction of order $v^2$ in quark velocity, and next-to-leading order corrections in $\alpha_s$ for longitudinally polarized production. The relativistic corrections are found to be important for a good description of the HERA data, especially at small values of the photon virtuality. The next-to-leading order results for longitudinal production are evaluated numerically. We also demonstrate how the vector meson production provides complementary information to the structure functions for extracting the initial condition for the small-$x$ evolution of the dipole-proton scattering amplitude.

  5 citations

• Photon TMDs from uPDFevolv

  Hannes Jung, Sara Taheri Monfared, Thomas Wening

  SciPost Phys. Proc. 8, 132 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We present photon TMDs generated using the Parton Branching Method with QED evolution. We discuss the TMD’s properties and compare it to the gluon TMD. Two sets of TMDs differing in their initial evolution scale and the choice of the renormalisation scale are defined and compared to each other.

• $\Lambda$ Polarizing Fragmentation Function from Belle $e^+ e^-$ data

  Umberto D'Alesio, Francesco Murgia, Marco Zaccheddu

  SciPost Phys. Proc. 8, 131 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Experimental data from Belle Collaboration for the transverse polarization of $\Lambda$'s measured in $e^+ e^-$ annihilation processes are used to extract the polarizing fragmentation function (FF) within a TMD approach. We consider both associated and inclusive $\Lambda$ production, showing a quite consistent scenario. Good separation in flavor is obtained, leading to four independent FFs. Predictions for SIDIS processes at the EIC, crucial for understanding their universality and evolution properties, are also presented.

• 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

• High-energy logarithmic corrections to the QCD component of same-sign W-pair production

  Jeppe R. Andersen, Bertrand Ducloué, Conor Elrick, Andreas Maier, Graeme Nail, Jennifer M. Smillie

  SciPost Phys. Proc. 8, 129 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We describe the calculation of the QCD contribution to same-sign $W$-pair production, $pp\to e^\pm \nu_e \mu^\pm \nu_\mu jj$, resumming all contributions scaling as $\alpha_W^4 \alpha_s^{2+k}\log^k(\hat s/p_\perp^2)$ [arXiv:2107.06818]. These leading logarithmic contributions are enhanced by typical cuts used for Vector Boson Scattering (VBS) studies. We show that while the cross sections are little affected by these corrections, other more exclusive observables relevant for experimental studies are affected more significantly.

• Using coherent dipion photoproduction to image gold nuclei

  Spencer R. Klein

  SciPost Phys. Proc. 8, 128 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Vector meson photoproduction offers the opportunity to image target nuclei. The two-dimensional Fourier transform $d\sigma_{\rm coherent}/dt$ of coherent vector meson photoproduction gives the two-dimensional distribution of interaction sites in the target. Since vector meson photoproduction occurs, at lowest order, via two-gluon exchange, this is sensitive to gluon shadowing. We present an analysis of $\pi^+\pi^-$ photoproduction using data from the STAR detector and a study of $d\sigma_{\rm coherent}/dt$, with an emphasis on probing the nuclear shape and its systematic uncertainties.

  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

• Physics motivation and detector upgrades for the new era of the ATLAS experiment

  Jason Nielsen

  SciPost Phys. Proc. 8, 126 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The ATLAS experiment at CERN’s Large Hadron Collider (LHC) will be upgraded in two stages to prepare first for the Run 3 data-taking campaign, during which the integrated luminosity will roughly double, and then for the High-Luminosity LHC program with an ultimate integrated luminosity of up to 4 ab-1. These upgrades and high-statistics datasets will allow ATLAS to perform searches and precision measurements to constrain the Standard Model in yet-unexplored phase spaces and in the Higgs sector. This contribution summarizes the ATLAS detector upgrades and selected physics prospects for Run 3 and the HL-LHC.

• Longitudinal and Transverse Spin Transfer of $Λ$ and $\overlineΛ$ Hyperons in Polarized $p$+$p$ Collisions at $\sqrt{s} = 200$ GeV at RHIC-STAR

  Yike Xu

  SciPost Phys. Proc. 8, 125 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Measurements of the longitudinal spin transfer, $D_{LL}$, and the transverse spin transfer, $D_{TT}$, of the $\Lambda(\bar{\Lambda}$) hyperon in polarized $p$+$p$ collisions are expected to be sensitive to the helicity distribution and transversity distribution of the $s(\bar{s})$ quark in proton and the corresponding polarized fragmentation functions. This contribution presents the new preliminary results of the $\Lambda(\bar{\Lambda}$) $D_{LL}$ and $D_{TT}$ using data collected at RHIC-STAR experiment in 2015, with twice larger statistics than previously published results.

• Intrinsic charm in the nucleon and forward production of charm: a new constrain from IceCube Neutrino Observatory

  Rafał Maciuła, Victor P. Goncalves, Antoni Szczurek

  SciPost Phys. Proc. 8, 124 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The predictions for the atmospheric neutrino flux at high energies strongly depend on the contribution of prompt neutrinos, which are determined by the production of charmed meson in the atmosphere at very forward rapidities. Here we estimate the related cross sections taking into account the presence of an intrinsic charm (IC) component in the proton wave function. The impact on the predictions for the prompt neutrino flux is investigated assuming different values for the probability to find the IC in the nucleon.