Publications

Order by: publication date number of citations

• Single-Logarithmic Corrections to Small-$x$ Helicity Evolution

  Yossathorn Tawabutr

  SciPost Phys. Proc. 8, 103 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The small-$x$ quark helicity evolution equations at double-logarithmic order, with the kernel $\sim\alpha_s\ln^2(1/x)$, have been derived previously. In this work, we derive the single-logarithmic corrections to the equations, to order $\alpha_s\ln(1/x)$ of the evolution kernel. The new equations include the effects of the running coupling and the unpolarized small-$x$ evolution, both of which are parametrically significant at single-logarithmic order. The large-$N_c$ and large-$N_c\& N_f$ approximations to the equation are computed. (Here, $N_c$ and $N_f$ are the numbers of quark colors and flavors, respectively.) Their solutions will provide more precise estimates of the quark helicity distribution at small $x$, contributing to the resolution of the proton spin puzzle.

  1 citation

• Azimuthal correlations in diffractive scattering at the Electron-Ion Collider

  Adrian Dumitru, Heikki Mäntysaari, Risto Paatelainen, Kaushik Roy, Farid Salazar, Björn Schenke

  SciPost Phys. Proc. 8, 102 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We calculate azimuthal correlations between the exclusively produced vector meson and the scattered electron in Deep Inelastic Scattering processes at the future Electron-Ion Collider (EIC). We identify "kinematical" and "intrinsic" contributions to these correlations, and show that the correlations are sensitive to the non-trivial correlations in the gluon distribution of the target. Realistic predictions at the EIC kinematics are provided using two different approaches to describe the dipole-proton interaction at relatively small $x$.

  1 citation

• PDF4LHC21: Update on the benchmarking of the CT, MSHT and NNPDF global PDF fits

  Thomas Cridge

  SciPost Phys. Proc. 8, 101 (2022) · published 13 July 2022 | Toggle abstract · pdf

  There have been recent updates to the three global PDF fits (CT, MSHT and NNPDF), all adding large amounts of data from the LHC, and this has resulted in significant changes to the global PDFs. Given the impact that the new PDFs will have on physics comparisons at the LHC, it is crucial to perform a benchmarking among the PDFs, similar in spirit to that which was carried out for PDF4LHC15, widely used for LHC physics. In this article we detail a benchmarking comparison of three global PDF sets - CT18, MSHT20 and NNPDF3.1 - and their similarities and differences that have been observed. The end result of this study will be a new PDF4LHC21 ensemble of combined PDFs suitable for a wide range of LHC applications.

  4 citations

• Simultaneous Extraction of Unpolarized PDFs and Nuclear Effects

  C. Cocuzza, A. Metz, N. Sato

  SciPost Phys. Proc. 8, 098 (2022) · published 13 July 2022 | Toggle abstract · pdf

  We present a new global QCD analysis of unpolarized parton distribution functions (PDFs) and nuclear effects including for the first time data from the SeaQuest and MARATHON experiments in addition to high-energy weak-boson-production data from the Tevatron and Large Hadron Collider. Simultaneously extracting the PDFs and nuclear effects, we examine the impact of the SeaQuest and MARATHON data on the light-quark sea asymmetry and the EMC ratios of deuterium, helium, and tritium.

• Production mechanisms of open heavy flavor mesons in high-multiplicity events

  Marat Siddikov, Ivan Schmidt

  SciPost Phys. Proc. 8, 096 (2022) · published 13 July 2022 | Toggle abstract · pdf

  In this proceeding we discuss different mechanisms of open-heavy flavor meson production which contribute to inclusive and single diffractive cross-sections. For the case of inclusive production we demonstrate that the three-Pomeron fusion is significant for the $D$-meson production in the kinematics of small transverse momenta $p_{T}$, as well as in large-multiplicity events. Its inclusion allows to improve significantly the description of experimental data. We also analyzed the diffractive production and found that due to gap survival factors it constitutes 0.5\textendash 2 per cent of the inclusive production. The expected dependence on event multiplicity in this channel is significantly milder than for inclusive case.

• Dark matter searches with mono-photon signature at future e$^+$e$^-$ colliders

  Jan Kalinowski, Wojciech Kotlarski, Krzysztof Mekala, Pawel Sopicki, Aleksander Filip Zarnecki

  SciPost Phys. Proc. 8, 095 (2022) · published 13 July 2022 | Toggle abstract · pdf

  As any e$^+$e$^-$ scattering process can be accompanied by a hard photon emission from the initial state radiation, the analysis of the energy spectrum and angular distributions of those photons can be used to search for hard processes with an invisible final state. Thus high energy e$^+$e$^-$ colliders offer a unique possibility for the most general search of Dark matter based on the mono-photon signature. We consider production of DM particles via a mediator at the International Linear Collider (ILC) and Compact Linear Collider (CLIC) experiments taking into account detector effects within the DELPHES fast simulation framework. Limits on the light DM production in a generic model are set for a wide range of mediator masses and widths. For mediator masses up to the centre-of-mass energy of the collider, results from the mono-photon analysis are more stringent than the limits expected from direct resonance searches in Standard Model decay channels.

  2 citations

• Exclusive emissions of rho-mesons and the unintegrated gluon distribution

  Andrèe Dafne Bolognino, Francesco Giovanni Celiberto, Dmitry Yu. Ivanov, Alessandro Papa

  SciPost Phys. Proc. 8, 089 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Exclusive emissions of vector mesons in forward directions of rapidity offer us a faultless chance to probe the proton structure at small-$x$. A high-energy factorization formula is established within BFKL, given as the convolution of an impact factor depicting the forward-meson emission and of an unintegrated gluon distribution (UGD) driving the gluon evolution at small-$x$. As a nonperturbative quantity, the UGD is not well known and several models for it exist. We present recent progresses on the study of the exclusive forward $\rho$-meson leptoproduction at HERA and EIC energies, showing how osbervables sensitive to different polarization states of the $\rho$-particle act as discriminators for the existing UGD models.

  7 citations

• A general-mass scheme for prompt charm production at hadron colliders

  Keping Xie, John M. Campbell, Pavel M. Nadolsky

  SciPost Phys. Proc. 8, 084 (2022) · published 12 July 2022 | Toggle abstract · pdf

  In these proceedings, we apply the recently developed S-ACOT-MPS factorization scheme at the next-to-leading order to prompt charm production at hadron colliders. It provides a good agreement with experimental data on charm meson production measured by LHCb at 7 and 13 TeV. The low-$p_T$ data are on the margins of the theoretical error bands, emphasizing the importance of including contributions beyond the next-to-leading order.

  3 citations

• A model for $F_L$ structure function at low values of $Q^2$ and $x$ - revisited

  Barbara Badelek, Anna Stasto

  SciPost Phys. Proc. 8, 082 (2022) · published 12 July 2022 | Toggle abstract · pdf

  A reanalysis of the model for the longitudinal structure function $F_L (x,Q^2)$ at low $x$ and low $Q^2$ was undertaken, in view of the advent of the EIC. The model includes the kinematic constraint $F_L\sim Q^4$ as $Q^2\rightarrow$ 0. It is based on the photon-gluon fusion mechanism suitably extrapolated to the region of low $Q^2$. Revised model was critically updated, extended to the EIC kinematic region, and e.g. contains new parameterisations of the parton distribution functions.

• PineAPPL: NLO EW corrections for PDF processes

  Christopher Schwan

  SciPost Phys. Proc. 8, 079 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Modern parton distribution function (PDF) determinations either neglect higher-order corrections in the electroweak (EW) coupling or implement them approximately for a subset of PDF processes. We present a new tool, PineAPPL, which supports perturbative correction in arbitrary powers of the EW and strong coupling constant, and stores theoretical predictions independently of the used PDFs in so-called interpolation grids. These are the foundation of any PDF determination, and will allow us to perform a PDF fit taking into account EW corrections for all processes consistently. Apart from PDF determinations PineAPPL can also be used in precision phenomenology to study the impact of different choices of PDF sets, without rerunning the time-consuming computation. As an application of this tool we show Drell-Yan (DY) lepton-pair production were larger effects of NLO EW corrections can be seen that will potentially influence the PDF fit and comment about which observables are particularly suited and NLO EW PDF fit and which are not.