Publications

Order by: publication date number of citations

• NLO collinear factorization of large mass diphoton photoproduction amplitude

  Oskar Grocholski, Bernard Pire, Paweł Sznajder, Lech Szymanowski, Jakub Wagner

  SciPost Phys. Proc. 8, 078 (2022) · published 12 July 2022 | Toggle abstract · pdf

  We calculate large mass diphoton exclusive photoproduction in the framework of collinear QCD factorization at next to leading order in {\alpha}s and at leading twist. Collinear divergences of the coefficient function are absorbed by the evolution of the generalized parton distributions (GPDs). This result enlarges the existing factorization proofs to 2 -> 3 processes, opening new reactions to a trustable extraction of GPDs.

• Spontaneous breaking of finite group symmetries at all temperatures

  Pedro Liendo, Junchen Rong, Haoyu Zhang

  SciPost Phys. 14, 168 (2023) · published 22 June 2023 | Toggle abstract · pdf

  We study conformal field theories with finite group symmetries with spontaneous symmetry breaking (SSB) phases which persist at all temperatures. We work with two $\lambda \phi^4$ theories coupled through their mass terms. The two $\lambda \phi^4$ theories are chosen to preserve either the cubic symmetry group, or the tetrahedral symmetry group. A one-loop calculation in the $4-\epsilon$ expansion shows that there exist infinitely many fixed points that can host an all temperature SSB phase. An analysis of the renormalization group (RG) stability matrix of these fixed points, reveals that their spectrum contains at least three relevant operators. In other words, these fixed points are tetracritical points.

• Measurements of jet substructure and jet fragmentation using the ATLAS detector

  Javier Llorente Merino

  SciPost Phys. Proc. 8, 080 (2022) · published 12 July 2022 | Toggle abstract · pdf

  Measurements of the internal properties of jets at the LHC interaction scale allow QCD to be studied in a new energy regime. In this talk, we discuss recent measurements of jet substructure and jet fragmentation, which were performed using data collected by the ATLAS experiment at a centre-of-mass energy of $\sqrt{s}=13$ TeV. The fragmentation properties of jets, such as the jet charge and summed fragmentation function, are measured using charged particles. A comprehensive suite of jet substructure observables is also measured for jets reconstructed with the soft-drop algorithm applied. In addition, a measurement of the Lund plane is performed using charged particles. All of the measurements are corrected for detector effects and are compared to the predictions of state-of-the-art Monte Carlo event generators.

• Indirect searches for dark matter with the nEDM spectrometer

  S. Roccia, G. Zsigmond on behalf of the nEDM collaboration at PSI

  SciPost Phys. Proc. 5, 028 (2021) · published 6 September 2021 | Toggle abstract · pdf

  The nEDM apparatus at PSI has been used to search for different dark matter signatures utilizing its high sensitivity to shifts in the neutron precession frequency and its well-controlled low magnetic field at the microT level. Such a shift could be interpreted as a consequence of a short-range spin-dependent interaction that could possibly be mediated by axions or axion-like particles, or as an axion-induced oscillating electric dipole moment of the neutron. Another search, based on so-called UCN disappearance measurements, targeted previously reported signals of neutron to mirror-neutron oscillations. These dark matter searches confirmed and improved previous results, as detailed in this review.

• Dark Matter searches with the ATLAS Detector

  Guglielmo Frattari

  SciPost Phys. Proc. 8, 085 (2022) · published 12 July 2022 | Toggle abstract · pdf

  The presence of a non-baryonic dark matter (DM) component in the Universe is inferred from the observation of its gravitational interaction. If dark matter interacts weakly with the Standard Model (SM) it could be produced at the LHC. The ATLAS experiment has developed a broad search program for DM candidates, including resonance searches for the mediator which would couple DM to the SM. The results of recent searches on 13 TeV pp data, their interplay and interpretation will be presented. Prospects for HL-LHC will also be discussed.

• Longitudinal double-spin asymmetries of inclusive jet and dijet production at STAR

  Maria Zurek

  SciPost Phys. Proc. 8, 086 (2022) · published 12 July 2022 | Toggle abstract · pdf

  At the STAR experiment, the gluon helicity distribution $\Delta g(x, Q^2)$ can be accessed through the double-spin asymmetries $A_{LL}$ of inclusive jet and dijet production in collisions of longitudinally polarized protons. These proceedings report on recently published results of $A_{LL}$ for inclusive jets and dijets at $\sqrt{s} = 200$~GeV and $\sqrt{s} = 510$ GeV in mid-pseudorapidity ($|\eta| < 1$) and preliminary results for dijets in intermediate pseudrapidity ($-0.8 < \eta < 1.8$). The mid-pseudorapidity jet and dijet measurements are sensitive to $\Delta g(x, Q^2)$ for gluon momentum fractions $x$ from $\simeq 0.5$ down to $\simeq 0.015$; the sensitivity region for dijets in intermediate pseudorapidity at 510 GeV extends to even lower $x$. The measurements are in good agreement with previous STAR results and recent theoretical evaluations of prior world data.

• Exploring unsupervised top tagging using Bayesian inference

  Ezequiel Alvarez, Manuel Szewc, Alejandro Szynkman, Santiago A. Tanco, Tatiana Tarutina

  SciPost Phys. Core 6, 046 (2023) · published 28 June 2023 | Toggle abstract · pdf

  Recognizing hadronically decaying top-quark jets in a sample of jets, or even its total fraction in the sample, is an important step in many LHC searches for Standard Model and Beyond Standard Model physics as well. Although there exists outstanding top-tagger algorithms, their construction and their expected performance rely on Montecarlo simulations, which may induce potential biases. For these reasons we develop two simple unsupervised top-tagger algorithms based on performing Bayesian inference on a mixture model. In one of them we use as the observed variable a new geometrically-based observable $\tilde{A}_{3}$, and in the other we consider the more traditional $\tau_{3}/\tau_{2}$ $N$-subjettiness ratio, which yields a better performance. As expected, we find that the unsupervised tagger performance is below existing supervised taggers, reaching expected Area Under Curve AUC $\sim 0.80-0.81$ and accuracies of about 69\% $-$ 75\% in a full range of sample purity. However, these performances are more robust to possible biases in the Montecarlo that their supervised counterparts. Our findings are a step towards exploring and considering simpler and unbiased taggers.

• 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.

• Possible studies of gluon transversity in the spin-1 deuteron at hadron-accelerator facilities

  S. Kumano, Qin-Tao Song

  SciPost Phys. Proc. 8, 100 (2022) · published 13 July 2022 | Toggle abstract · pdf

  Chiral-odd gluon transversity distribution could shed light on a new aspect of hadron physics. Although we had much progress recently on quark transversity distributions, there is no experimental measurement on the gluon transversity. The gluon trasversity does not exist in the spin-1/2 nucleons and it exists in the spin-1 deuteron. Therefore, it could probe new hadron physics in the deuteron beyond the basic bound system of a proton and a neutron because the nucleons cannot contribute directly. Here, we explain that the gluon transversity can be measured at hadron accelerator facilities, such as Fermilab and NICA, in addition to charged-lepton scattering measurements at lepton accelerator facilities by showing cross sections of the proton-deuteron Drell-Yan process as an example.

• Dark matter directionality approach using ZnWO$_4$ crystal scintillators

  Vincenzo Caracciolo, Volodymyr Yakovych Degoda, Pierluigi Belli, Rita Bernabei, Y. A. Borovlev, Fabio Cappella, Riccardo Cerulli, Fedor A. Danevich, Antonella Incicchitti, Alice Leoncini, Vittorio Merlo, N. Cherubini, Dmytro V. Kasperovych, Y. P. Kogut, G. P. Podust, Oksana G. Polischuk, A. G. Postupaeva, V. N. Shlegel, Volodymyr I. Tretyak

  SciPost Phys. Proc. 12, 021 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The development of low-background anisotropic detectors can offer a unique way to study those Dark Matter (DM) candidate particles able to induce nuclear recoils through the directionality technique. Among the anisotropic scintillators, the ZnWO$_{4}$ has unique features and is an excellent candidate for the purposes. Both the light output and the scintillation pulse shape depend on the impinging direction of heavy particles with respect to the crystallographic axes and can supply two independent modes to study the directionality and discriminate $\gamma/\beta$ radiation. Measurements to study the anisotropic and scintillation performances of ZnWO$_4$ are reported.