Publications

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• Improved treatment of dark matter capture in compact stars

  Sandra Robles

  SciPost Phys. Proc. 12, 057 (2023) · published 5 July 2023 | Toggle abstract · pdf

  Compact stellar objects are promising cosmic laboratories to test the nature of dark matter (DM). DM captured by the strong gravitational field of these stellar remnants transfers kinetic energy to the star during the collision. This can have various effects such as anomalous heating of old compact stars. The proper calculation of the DM capture rate is key to derive bounds on DM interactions in any scenario involving DM accretion in a star. We improve former calculations, which rely on approximations, for both white dwarfs (WDs) and neutron stars (NSs). We account for the stellar structure, gravitational focusing, relativistic kinematics, Pauli blocking, realistic form factors, and strong interactions (NSs). Considering DM capture by scattering off either ions or degenerate electrons in WDs, we show that old WDs in DM-rich environments could probe the elusive sub-GeV mass regime for both DM-nucleon and DM-electron scattering. In NSs, DM can be captured via collisions with strongly interacting baryons or relativistic leptons. We project the NS sensitivity to DM-nucleon and DM-lepton scattering cross sections which greatly exceeds that of direct detection experiments, especially for low mass DM.

  1 citation

• ELOISE - Reliable background simulation at sub-keV energies

  Holger Kluck

  SciPost Phys. Proc. 12, 064 (2023) · published 5 July 2023 | Toggle abstract · pdf

  CaWO$_4$ and Al$_2$O$_3$ are well-established target materials used by experiments searching for rare events like the elastic scattering off of a hypothetical Dark Matter particle. In recent years, experiments have reached detection thresholds for nuclear recoils at the 10 eV-scale. At this energy scale, a reliable Monte Carlo simulation of the expected background is crucial. However, none of the publicly available general-purpose simulation packages are validated at this energy scale and for these targets. The recently started ELOISE project aims to provide reliable simulations of electromagnetic particle interactions for this use case by obtaining experimental reference data, validating the simulation code against them, and, if needed, calibrating the code to the reference data.

  1 citation

• The all-particle energy spectrum of cosmic rays from 10 TeV to 1 PeV measured with HAWC

  Jorge A. Morales-Soto, Juan C. Arteaga-Velázquez on behalf of the HAWC Collaboration

  SciPost Phys. Proc. 13, 039 (2023) · published 29 September 2023 | Toggle abstract · pdf

  The HAWC observatory is an air-shower detector, which is designed to study both astrophysical gamma-rays in the TeV region and galactic cosmic rays in the energy interval from 1 TeV to 1 PeV. This energy regime is interesting for cosmic ray research, since indirect observations overlap with direct measurements, which offers the opportunity for cross calibration and studies of experimental systematic errors in both techniques. One quantity that could help for this purpose is the all-particle energy spectrum of cosmic rays. In this work, we present an update of HAWC measurements on the total cosmic-ray energy spectrum between 10 TeV and 1 PeV. The spectrum was obtained from an unfolding analysis of almost two years of HAWC's data, which was collected from January, 2018 to December, 2019. For the energy estimation, we employed the high-energy hadronic interaction model QGSJET-II-04. As in a previous work of HAWC, published in 2017, we observed the presence of a knee-like feature in the region of tens of TeV.

  1 citation

• The pion-photon transition form factor at two loops in QCD

  Jing Gao, Tobias Huber, Yao Ji, Yu-Ming Wang

  SciPost Phys. Proc. 7, 022 (2022) · published 21 June 2022 | Toggle abstract · pdf

  We report on the fully analytic calculation of the leading-power contribution to the photon-pion transition form factor $\gamma \, \gamma^{\ast} \to \pi^0$ at two loops in QCD. The applied techniques are based on hard-collinear factorization, together with modern multi-loop methods. We focus both, on the technical details such as the treatment of evanescent operators, and the phenomenological implications. Our results indicate that the two-loop correction is numerically comparable to the one-loop effect in the same kinematic domain. We also demonstrate that our results will play a key role in disentangling various models for the twist-two pion distribution amplitude thanks to the envisaged precision at Belle II.

  1 citation

• First measurement results from DANAE - Demonstrating DePFET RNDR on a prototype Matrix

  Alexander Bähr, Holger Kluck, Peter Lechner, Jelena Ninkovic, Jochen Schiek, Hexi Shi, Wolfgang Treberspurg, Johannes Treis

  SciPost Phys. Proc. 12, 066 (2023) · published 5 July 2023 | Toggle abstract · pdf

  In the search for dark matter particle candidates, the mass region below 1 GeV/c$^2$ is relatively unprobed. Utilizing a low-noise silicon sensor as a sensitive target material, we aim to study the event signature of recoils between dark matter candidates and bound electrons. As the deposited energy is only a few eV, a sensor capable of detecting these low signals is required. We present first measurements on a prototype pixel matrix. It is based on the RNDR DePFET principle and provides a deep sub-electron readout noise of 0.2e$^-$ and below.

  1 citation

• Exploring coherent elastic neutrino-nucleus scattering of reactor neutrinos with the NUCLEUS experiment

  C. Goupy, H. Abele, G. Angloher, A. Bento, L. Canonica, F. Cappella, L. Cardani, N. Casali, R. Cerulli, I. Colantoni, A. Cruciani, G. del Castello, M. del Gallo Roccagiovine, A. Doblhammer, S. Dorer, A. Erhart, M. Friendl, A. Garai, V. M. Ghete, D. Hauff, F. Jeanneau, E. Jericha, M. Kaznacheeva, A. Kinast, H. Kluck, A. Langenkämper, T. Lasserre, D. Lhuillier, M. Mancuso, B. Mauri, A. Mazzolari, E. Mazzucato, H. Neyrial, C. Nones, L. Oberauer, T. Ortmann, L. Pattavina, L. Peters, F. Petricca, W. Potzel, F. Pröbst, F. Pucci, F. Riendl, R. Rogly, M. Romagnoni, J. Rothe, N. Schermer, J. Schieck, S. Schönert, C. Schwertner, L. Scola, G. Soum Sidikov, L. Stodolsky, R. Strauss, M. Tamisari, C. Tomei, M. Vignati, M. Vivier, V. Wagner, A. Wex (The NUCLEUS collaboration)

  SciPost Phys. Proc. 12, 053 (2023) · published 5 July 2023 | Toggle abstract · pdf

  The NUCLEUS experiment aims to perform a high-precision measurement of Coherent Elastic Neutrino-Nucleus Scattering (CEvNS) at the EdF Chooz B nuclear power plant in France. CEvNS is a unique process to study neutrino properties and to search for physics beyond the Standard Model. The study of CEvNS is also important for light Dark-Matter searches. It could be a possible irreducible background for high-sensitivity Dark-Matter experiments. NUCLEUS is an experiment under construction based on ultra-low threshold ($\sim$20 eV$_{nr}$) cryogenic calorimeters, operated at tens-of-mK temperatures.

  1 citation

• LUXE: A new experiment to study non-perturbative QED in $e^{-}$-laser and $γ$-laser collisions

  Ruth Jacobs

  SciPost Phys. Proc. 8, 088 (2022) · published 13 July 2022 | Toggle abstract · pdf

  The LUXE experiment (Laser Und XFEL Experiment) is a new experiment in planning at DESY Hamburg using the electron beam of the European XFEL. LUXE is intended to study collisions between a high-intensity optical laser and up to 16.5 GeV electrons from the Eu.XFEL electron beam, or, alternatively, high-energy secondary photons. The physics objective of LUXE are processes of Quantum Electrodynamics (QED) at the strong-field frontier, where QED is non-perturbative. This manifests itself in the creation of physical electron-positron pairs from the QED vacuum. LUXE intends to measure the positron production rate in a new physics regime at an unprecedented laser intensity. Parasitically, the high-intensity Compton photon beam of LUXE can be used to search for physics beyond the Standard Model.

  1 citation

• CJ15 global PDF analysis with new electroweak data from the STAR and SeaQuest experiments

  Sanghwa Park, Alberto Accardi, Xiaoxian Jing, Joseph F. Owens

  SciPost Phys. Proc. 8, 177 (2023) · published 11 July 2023 | Toggle abstract · pdf

  We present updates to a recent CTEQ-Jefferson Lab (CJ) global analysis of parton distribution functions with a new set of electroweak data that provide unique access to quark flavor separation in the proton. In particular, recent $W$ and $Z$ boson measurements from the STAR experiment at RHIC put additional constraints on light quarks and antiquarks near the valence regime. The new measurement of the Drell-Yan lepton pair production ratio in $p+p$ and $p+d$ collisions by the SeaQuest experiment at Fermilab extends the large-$x$ coverage of the previous E866 experiment and sheds new light on the light antiquarks distribution. In this report, the impact of these new data sets on parton distribution functions will be presented with emphasis given to the flavor asymmetry of the light antiquark sea at large values of the parton momentum $x$.

  1 citation

• Feynman integrals for binary systems of black holes

  Philipp Alexander Kreer, Robert Runkel, Stefan Weinzierl

  SciPost Phys. Proc. 7, 023 (2022) · published 21 June 2022 | Toggle abstract · pdf

  The initial phase of the inspiral process of a binary black-hole system can be described by perturbation theory. At the third post-Minkowskian order a two-loop double box graph, known as H-graph, contributes. In this talk we report how all master integrals of the H-graph with equal masses can be expressed up to weight four in terms of multiple polylogarithms. We also discuss techniques for the unequal mass case. The essential complication (and the focus of the talk) is the occurrence of several square roots.

  1 citation

• 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