Publications

Order by: publication date number of citations

• Measurement of low-energy Compton and neutron scattering in Si CCDs for dark matter searches

  Radomir Smida for the DAMIC-M Collaboration

  SciPost Phys. Proc. 12, 015 (2023) · published 3 July 2023 | Toggle abstract · pdf

  For optimal sensitivity to low-mass dark matter candidates experiments like DAMIC-M employ skipper charged-coupled devices (CCDs) with detection threshold of just a few ionization charges. Ionization signals from small-angle Compton scatters of environmental $\gamma$-rays, an important component of the background in dark matter searches, must thus be characterized down to $O$(10 eV) energy. Using a $^{241}$Am $\gamma$-ray source, we report a precise measurement of scattering on Si atomic shell electrons in a skipper CCD with single-electron resolution. Notable differences are observed between data and theoretical expectations in the L-shell energy region ($<$150 eV). We also present preliminary data from a skipper CCD exposed to low-energy neutrons ($<$24 keV) from a $^{124}$Sb$^9$Be photoneutron source, demonstrating a measurement of the nuclear recoil ionization efficiency in Si down to few ionization charges.

• Dark matter searches and energy accumulation and release in materials

  Sergey Pereverzev

  SciPost Phys. Proc. 12, 009 (2023) · published 3 July 2023 | Toggle abstract · pdf

  Efforts to identify dark matter by detecting nuclear recoils produced by dark matter particles reveal low-energy backgrounds of unknown origin in different types of detectors. In many cases, energy accumulation and delayed burst-like releases of stored energy could provide an explanation. These dynamics follow Prigogine's ideas on systems with energy flow and the general Self-Organized Criticality scenario. We compare these models with properties of excess backgrounds in cryogenic solid-state detectors, relaxation processes in glasses and crystals, our observations of delayed luminescence in NaI(Tl), and make predictions for more phenomena present in these systems and in superconducting photon detectors and qubits. Experiments to create accurate phenomenological models are needed.

• Annual modulation of dark matter signals: Experimental results and new ideas

  Felix Kahlhoefer

  SciPost Phys. Proc. 12, 004 (2023) · published 3 July 2023 | Toggle abstract · pdf

  Direct detection experiments searching for the scattering of dark matter particles off nuclei expect an annual modulation in their event rate. In this presentation, I will review the theoretical predictions and the experimental status of the search for annual modulations, with a focus on ongoing and planned experiments using NaI detectors. In particular, I will discuss the interpretation of the DAMA signal and related model-building efforts.

• New determination of the production cross section for secondary positrons and electrons in the Galaxy

  Luca Orusa, Mattia Di Mauro, Fiorenza Donato, Michael Korsmeier

  SciPost Phys. Proc. 13, 006 (2023) · published 28 September 2023 | Toggle abstract · pdf

  The cosmic-ray fluxes of electrons and positrons ($e^{±}$) are measured with high precision by the space-borne particle spectrometer AMS-02. To infer a precise interpretation of the production processes for $e^{±}$ in our Galaxy, it is necessary to have an accurate description of the secondary component, produced by the interaction of cosmic-ray proton and helium with the interstellar medium atoms. We determine new analytical functions of the Lorentz invariant cross section for the production of $e^±$ by fitting data from collider experiments. The total differential cross section $d\sigma/dT_{e^±}(p+p→ e^±+X)$ is predicted with an uncertainty of about 5-7% in the energies relevant for AMS-02 positron flux. For further information about this work refer to [Phys. Rev. D 105, 123021 (2022)].

• Sivers extraction with Neural Network

  I. P. Fernando, N. Newton, D. Seay, D. Keller

  SciPost Phys. Proc. 8, 035 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Psuedo-data with simulated experimental errors can be generated to train an ensemble of Artificial Neural Networks (ANN) implemented on a regression to extract Transverse Momentum-dependent Distributions (TMDs). A preliminary analysis is presented on the reliability in extraction of the Sivers function imposed in the pseudo-data given the bounds on the experimental errors, data sparsity, and complexity of phase-space.

• 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.

• Recent Studies of Exotic Hadrons at the LHCb Experiment

  Gary Robertson

  SciPost Phys. Proc. 8, 030 (2022) · published 11 July 2022 | Toggle abstract · pdf

  Recent results on studies of exotic hadrons at the LHCb experiment are summarised. These are the observation of new resonances decaying to J/$\psi K^{+}$ and J/$\psi\phi$, evidence of a J/$\psi\Lambda$ structure and observation of excited $\Xi^{-}$ states in the $\Xi_{b}^{-}\to J/\psi \Lambda K^{-}$ decay and the study of $B_{s}^{0}\to J/\psi\pi^{+}\pi^{-}K^{+}K^{-}$ decays.

• Azimuthal single- and double-spin asymmetries in semi-inclusive deep-inelastic lepton scattering by transversely polarized protons

  Luciano L. Pappalardo, Gunar Schnell

  SciPost Phys. Proc. 8, 024 (2022) · published 11 July 2022 | Toggle abstract · pdf

  A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi- inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining single-spin and double-spin asymmetries for transverse target-polarization orientation.

• 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.

• SO(1,3) Yang-Mills solutions on Minkowski space via cosets

  Kaushlendra Kumar

  SciPost Phys. Proc. 14, 033 (2023) · published 24 November 2023 | Toggle abstract · pdf

  We present a novel family of Yang-Mills solutions, with gauge group SO(1,3), on Minkowski space that are geometrically distinguished into two classes, viz. interior and exterior of the lightcone. We achieve this by foliating the former with SO(1,3)/SO(3) cosets and the latter with SO(1,3)/SO(1,2) cosets and analytically solving the Yang-Mills equation of an SO(1,3)-invariant gauge field. The resulting fields and their stress-energy tensor, when translated to the Minkowski space, diverge at the lightcone, but we demonstrate how this stress-energy tensor could be regularised due to its unique algebraic structure.