Publications

Order by: publication date number of citations

• Prospects of a future multi-TeV muon collider

  M. Casarsa

  SciPost Phys. Proc. 8, 061 (2022) · published 12 July 2022 | Toggle abstract · pdf

  A multi-TeV muon collider is a discovery machine and an invaluable tool for many new standard model precision measurements such as the shape of the Higgs boson potential. The update of the European Strategy for Particle Physics recognized the unique opportunity of a muon collider to reach the energy frontier, despite the challenges to produce intense collimated muon beams. The options of a collider at 3 TeV and a collider at 10 TeV or above are the main focus of the forming International Muon Collider Collaboration as well as of the discussion panels at the ongoing US Snowmass process.

• A new method to extract the valence transversity distributions

  Mauro Anselmino, Raj Kishore, Asmita Mukherjee

  SciPost Phys. Proc. 8, 052 (2022) · published 12 July 2022 | Toggle abstract · pdf

  A new method is suggested for the extraction of $u$-quark and $d$-quark transversity distributions, using single spin asymmetry (SSA) data in semi-inclusive deep inelastic scattering (SIDIS) processes, where they couple to the Collins or the di-hadron fragmentation functions. We discuss a recent suggestion to extract the transversity distribution using the concept of difference asymmetries and their ratios, which avoids the requirement of Collins function. We suggest new measurements, involving ratios of polarized cross-sections, that would directly probe the ratio $h_1^{d_v}/h_1^{u_v}$. We also show some numerical estimates.

• 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.

• Global Analysis of SSAs and the Impact of the EIC and SoLID on Tensor Charge Extractions

  Daniel Pitonyak

  SciPost Phys. Proc. 8, 044 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Single transverse-spin asymmetries (SSAs) give great insight into the 3-dimensional structure of hadrons. We report on the first global QCD analysis of SSAs in semi-inclusive deep-inelastic scattering, electron-positron annihilation, Drell-Yan, and single-inclusive proton-proton collisions. One byproduct of the analysis is an extraction of the transversity function, from which the nucleon tensor charges can be computed, and we find, for the first time, agreement with lattice QCD for these quantities. Based on this analysis, we perform an impact study of future data on extractions of the nucleon tensor charges.

• A novel formulation of the unintegrated gluon distribution for DIS

  Yacine Mehtar-Tani

  SciPost Phys. Proc. 8, 037 (2022) · published 12 July 2022 | Toggle abstract · pdf

  In this talk, we revisit inclusive DIS in the small $x$ limit and derive a new factorization formula that accounts for leading powers in both Bjorken and Regge limits. In this semi-classical description, we obtain a new unintegrated gluon distribution which encompasses both the dipole operator and the gluon Parton Distribution Function with an explicit dependence on the longitudinal momentum fraction $x$.

• Backward-Angle (u-Channel) Meson Production from JLab 12~GeV Hall C to EIC

  Wenliang B. Li

  SciPost Phys. Proc. 8, 036 (2022) · published 12 July 2022 | Toggle abstract · pdf

  The recent exclusive backward-angle electroproduction of omega from Jefferson Lab Hall C electron-proton fixed-target scattering experiments above the resonance region hints at a new domain of applicability of QCD factorization in a unique u-channel kinematics regime. Thanks to this effort, the interest in studying nucleon structure through u-channel meson production observables has grown significantly. In the fixed target configuration, theu-channel meson electroproduction observables feature a unique interaction picture: the target proton absorbs nearly all momentum induced by virtual photons and recoils forward, while the produced mesons (such as omega or pions) are left behind almost at rest near the target station. In this presentation, We provide a summary of the key observations of the existing u-channel meson production results, update-to-date theory insights, and a path to further exploration from JLab 12 GeV Hall C program to the future Electron-Ion Colliders

• Prompt hadroproduction of C-even quarkonia in the light-front $k_T$ -factorization approach

  Wolfgang Schäfer, Izabela Babiarz, Roman Pasechnik, Antoni Szczurek

  SciPost Phys. Proc. 8, 032 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present a new approach for the prompt production of quarkonia which is based on the $k_T$-factorization method. The production of even C-parity quarkonia proceeds via the fusion of two (off-shell) gluons. Especially in the kinematics of the LHCb experiment these processes are thus expected to be a sensitive probe of the small-x gluon distribution. We calculate the relevant off-shell matrix elements in terms of the light-front wave functions of the quarkonium states. We present our results for scalar and pseudoscalar charmonia and discuss photon transition form factors as well as cross sections for prompt hadroproduction. We compare our results for the $\eta_c$ to recent LHCb data.

• Measurements of W and Z boson production in ATLAS

  Zhibo Wu

  SciPost Phys. Proc. 8, 031 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Precision measurements of the production cross-sections of W and Z boson at LHC provide important tests of perturbative QCD and information about the parton distribution functions for quarks within the proton. We present measurements of cross sections for inclusive $W^+$, $W^{-}$ and Z boson production using data collected by the ATLAS experiment at a center-of-mass energy of $\sqrt{s}$=2.76 TeV. Measurement of the transverse momentum distribution of Z boson at $\sqrt{s}$=13 TeV is also presented. The measurements are corrected for detector effects and compared with state-of-the-art theoretical calculations.

• Quark Sivers Function at Small-$x$: Leading contribution from the Spin-Dependent Odderon

  M. Gabriel Santiago

  SciPost Phys. Proc. 8, 027 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present the calculation of the leading contribution to the quark Sivers function at small-Bjorken $x$. This calculation uses the high energy scattering approximation and operator formalism developed by Kovchegov and Sievert to obtain a dominant contribution to the quark Sivers function coming from the spin-dependent odderon, in agreement with the results of Dong, Zhen, and Zhou. We then calculate this dominant contribution in the diquark model of the proton to obtain a small-$x$ estimate for the Sivers function.

• Forward trijet production and saturation

  Andreas van Hameren

  SciPost Phys. Proc. 8, 022 (2022) · published 11 July 2022 | Toggle abstract · pdf

  We present a multi-parton extension of the so-called small-$\boldsymbol{x}$ Improved Transverse Momentum Dependent (ITMD) factorization for hadroproduction of three or more jets in the forward rapidity region, allowing to study gluon saturation using such processes.