Publications

Order by: publication date number of citations

• Dijet production at EIC and interplay of Sudakov and saturation effects in Weizsacker-Williams TMD gluon distribution

  Piotr Kotko

  SciPost Phys. Proc. 8, 020 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We study production of dijets at the EIC using the small-x Improved Transverse Momentum Dependent factorization (ITMD), which is a framework based on the Color Glass Condensate theory. Dijet production in DIS is the simplest process directly coupled to the Weizsacker-Williams TMD gluon distribution, which is the only small-x gluon distribution possessing the gluon number density interpretation. We study various observables sensitive to the interplay of the Sudakov effects and the nonlinear effects, in particular the azimuthal correlations between the jet system and the scattered electron.

• Charmonium and bottomonium spectroscopy at Belle II

  Ashish Thampi

  SciPost Phys. Proc. 8, 019 (2022) · published 11 July 2022 | Toggle abstract · pdf

  The Belle II experiment at the SuperKEKB energy-asymmetric e+e− collider is an upgrade of the B factory facility at KEK in Tsukuba, Japan. The experiment began operation in 2019 and aims to record a factor of 50 times more data than its predecessor. Belle II is uniquely capable of studying the so-called "XYZ" particles: heavy exotic hadrons consisting of more than three quarks. First discovered by Belle, these now number in the dozens, and represent the emergence of a new category within quantum chromodynamics. We present recent results obtained from Belle II data, and the future prospects to explore both exotic and conventional quarkonium physics.

• The MSHT20 Parton Distribution Functions

  R.S. Thorne, S. Bailey, T. Cridge, L. Harland-Lang, A.D. Martin

  SciPost Phys. Proc. 8, 018 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present the new MSHT20 set of parton distribution functions (PDFs) of the proton, determined from a global analysis of the available hard scattering data and superseding the MMHT14 sets. The parameterisation is now adapted and extended and we include a large number of new data sets: the final HERA and Tevatron data, and a significant number of LHC data sets on vector boson production, inclusive jets and top quark distributions. We include up to NNLO QCD corrections for all data sets that play a major role in the fit. There are some changes to central PDF values and a significant reduction in the uncertainties, but the PDFs and the predictions using them are generally within one standard deviation of the MMHT14 results. We discuss the phenomenological impact of our results.

  3 citations

• Sivers asymmetry in inelastic $J/ψ$ leptoproduction at the EIC

  Sangem Rajesh, Umberto D'Alesio, Asmita Mukherjee, Francesco Murgia, Cristian Pisano

  SciPost Phys. Proc. 8, 017 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We study the Sivers asymmetry in inelastic $J/\psi$ leptoproduction, $ep^\uparrow \to e+ J/\psi+X$, within a transverse momentum dependent scheme, the so-called generalized parton model (GPM). The effects of final-state interactions are properly taken into account by employing the color-gauge invariant GPM (CGI-GPM). For the $J/\psi$ formation the non-relativistic QCD (NRQCD) framework is adopted. Predictions for unpolarized cross sections and maximized Sivers asymmetries at EIC energies are given.

• Longitudinal Z-boson polarization and the Higgs boson production cross-section

  Simone Amoroso

  SciPost Phys. Proc. 8, 016 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Lepton pairs are produced copiously in high-energy hadron collisions via electroweak gauge boson exchange, and are one of the most precisely measured final states in proton- proton collisions at the Large Hadron Collider (LHC). We propose that measurements of lepton angular distributions can be used to improve the accuracy of theoretical predic- tions for Higgs boson production cross sections at the LHC. To this end, we exploit the sensitivity of the lepton angular coefficient associated with the longitudinal Z-boson polarization to the parton density function (PDF) for gluons resolved from the incoming protons, in order to constrain the Higgs boson cross section from gluon fusion processes. By a detailed numerical analysis using the open-source platform xFitter, we find that high-statistics determinations of the longitudinally polarized angular coefficient at the LHC Run III and high-luminosity HL-LHC improve the PDF systematics of the Higgs boson cross section predictions by 50 % over a broad range of Higgs boson rapidities.

• Hard color-singlet exchange in dijet events in proton-proton collisions at $\sqrt{s} = 13$ TeV

  Cristian Baldenegro Barrera

  SciPost Phys. Proc. 8, 015 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present a measurement of events with two jets separated by a pseudorapidity gap (jet-gap-jet). The signature is expected from hard color-singlet exchange. The jets are reconstructed with the CMS detector. The highest $p_\text{T}$ jets have $p_\text{T}^\text{jet1,2} > 40$ GeV, with $1.4 < |\eta^\text{jet1,2}| < 4.7$ and $\eta^\text{jet1} \eta^\text{jet2} < 0$. We measure the fraction of color-singlet exchange dijet events, $f_\text{CSE}$, and compare it to previous measurements and to predictions. We also study jet-gap-jet events where the colliding protons remain intact and are detected with the Roman pots of TOTEM. A larger fraction $f_\text{CSE}$ is found in the latter subsample.

• ATLAS results on charmonium production

  Vato Kartvelishvili

  SciPost Phys. Proc. 8, 014 (2022) · published 11 July 2022 | Toggle abstract · pdf

  An overview is given of the results on charmonium production obtained by the ATLAS collaboration at the LHC. Recent preliminary measurements covering prompt and non-prompt production of $J/\psi$ and $\psi(2S)$ states in the range of high transverse momenta from 60 to 360~GeV are highlighted.

• PERLE - ERL Test Facility at Orsay

  S.A. Bogacz

  SciPost Phys. Proc. 8, 013 (2022) · published 11 July 2022 | Toggle abstract · pdf

  PERLE (Powerful ERL for Experiments) is a novel Energy Recovery Linac (ERL) test facility, designed to validate choices for a 50 GeV ERL foreseen in the design of the Large Hadron Electron Collider (LHeC) and the Future Circular Collider (FCC-eh), and to host dedicated nuclear and particle physics experiments. Its main thrust is to probe high current, continuous wave (CW), multi-pass operation with superconducting cavities at 802 MHz. With very high transient beam power (10 MW), PERLE offers an opportunity for controllable study of every beam dynamic effect of interest in the next generation of ERL design and becomes a ‘stepping stone’ between present state-of-art 1 MW ERLs and future 100 MW scale applications.

  1 citation

• Transverse Single Spin Asymmetries of Heavy Flavor Electrons and Charged Pions in 200 GeV $p+p^{\uparrow}$ Collisions at Midrapidity

  Dillon Fitzgerald

  SciPost Phys. Proc. 8, 012 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Transverse single spin asymmetries of particles produced in $p+p^{\uparrow}$ collisions provide insight on the partonic spin and momentum structure of hadrons; heavy flavor electrons provide access to initial state spin-momentum correlations of gluons in the proton, while charged pions provide access to initial and final state transverse spin effects. Charged particles are measured at midrapidity at PHENIX using the silicon vertex detector and central arm spectrometer, made of an electromagnetic calorimeter, a ring-imaging Cherenkov detector, and drift and pad chambers. Recent results for both electron and charged pion measurements from the 2015 running period will be presented.

• NLO inclusive $J/ψ$ photoproduction at large $P_T$ at HERA and the EIC

  Carlo Flore, Jean-Philippe Lansberg, Hua-Sheng Shao, Yelyzaveta Yedelkina

  SciPost Phys. Proc. 8, 011 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We study inclusive $J/\psi$ photoproduction at NLO at large $P_T$ at HERA and the EIC. Our computation includes NLO QCD leading-$P_T$ corrections, QED contributions via an off-shell photon as well as those from $J/\psi$+charm channels. For the latter, we employ the variable-flavour-number scheme. Our results are found to agree with the latest HERA data by H1 and provide, for the first time, a reliable estimate of the EIC reach for such a measurement. Finally, we demonstrate the observability of $J/\psi$+charm production and the sensitivy to probe the non-perturbative charm content of the proton at high $x$, also known as intrinsic charm, at the EIC.