Publications

Order by: publication date number of citations

• Ruling out QCD phase transition as a PBH origin of LIGO/Virgo events

  Joaquim Iguaz Juan

  SciPost Phys. Proc. 12, 052 (2023) · published 5 July 2023 | Toggle abstract · pdf

  The best-motivated scenario for a sizable primordial black hole (PBH) contribution to the LIGO/Virgo binary black hole mergers invokes the QCD phase transition, which naturally enhances the probability to form PBH with masses of stellar scale. We reconsider the expected mass function assuming a CMB-like primordial spectrum and associated not only to the QCD phase transition proper, but also the $e^{+}e^{-}$ annihilation process, and analyze the constraints on this scenario from a number of observations. We find that the scenario is not viable, unless an ad hoc mass evolution for the PBH mass function and a cutoff in power-spectrum very close to the QCD scale are introduced by hand.

• Improved Galactic diffuse emission model strengthens the case for a Millisecond Pulsar explanation of the Fermi GeV excess

  Oscar Macias, Martin Pohl, Chris Gordon, Phaedra Coleman

  SciPost Phys. Proc. 12, 049 (2023) · published 4 July 2023 | Toggle abstract · pdf

  After more than a decade since its discovery, the Galactic center gamma-ray excess - discovered with the Fermi Large Area Telescope - remains puzzling. While the spectrum of the signal can be explained by either dark matter or an unresolved population of millisecond pulsars, the spatial morphology of this excess seems to hold the key to separate the two theories. In this contribution, we present the results of a recent study in which we use bleeding edge models for interstellar gas, inverse Compton emission, and stellar mass models to reanalyze the Galactic center excess. We find that the spatial morphology of the excess is highly correlated with stellar matter in the Galactic bulge, providing strong support for the millisecond pulsar hypothesis.

• ISAI: Investigating Solar Axion by Iron-57

  Tomonori Ikeda, Toshihiro Fujii, Takeshi Go Tsuru, Yuki Amano, Kazuho Kayama, Masamune Matsuda, Hiromu Iwasaki, Mizuki Uenomachi, Kentaro Miuchi, Yoshiyuki Onuki, Yoshizumi Inoue, Akimichi Taketa

  SciPost Phys. Proc. 12, 041 (2023) · published 4 July 2023 | Toggle abstract · pdf

  The existence of the axion is a unique solution for the strong CP problem, and the axion is one of the most promising candidates of the dark matter. Investigating Solar Axion by Iron-57 (ISAI) is being prepared as a complemented table-top experiment to confirm the solar axion scenario. Probing an X-ray emission from the nuclear transitions associated with the axion-nucleon coupling is a leading approach. ISAI searches for the monochromatic 14.4 keV X-ray from the first excited state of $^{57}$Fe using a state-of-the-art pixelized silicon detector, dubbed XRPIX, under an extremely low-background environment. We highlight scientific objectives, experimental design and the latest status of ISAI.

• Searching for wave-like dark matter with QSHS

  Ian Bailey, Bhaswati Chakraborty, Gemma Chapman, Edward J. Daw, John Gallop, Gianluca Gregori, Edward Hardy, Ling Hao, Edward Laird, Peter Leek, John March-Russell, Phil Meeson, Seaárbhan Ó Peatáin, Yuri Pashkin, Mitchell G. Perry, Michele Piscitelli, Edward Romans, Subir Sarkar, Paul J. Smith, Ningqiang Song, Mahesh Soni, Boon K. Tan, Stephen West, Stafford Withington

  SciPost Phys. Proc. 12, 040 (2023) · published 4 July 2023 | Toggle abstract · pdf

  In 2021 the Quantum Sensors for the Hidden Sector (QSHS) collaboration was founded in the UK and received funding to develop and demonstrate quantum devices with the potential to detect hidden sector particles in the $\mu$eV to 100 $\mu$eV mass window. The collaboration has been developing a range of devices. It is building a high-field, low-temperature facility at the University of Sheffield to characterise and test the devices in a haloscope geometry. This paper introduces the collaboration's motivation, aims, and progress.

• Approaching the first any light particle search II science run

  Aaron D. Spector for the ALPS Collaboration

  SciPost Phys. Proc. 12, 039 (2023) · published 4 July 2023 | Toggle abstract · pdf

  The Any Light Particle Search II (ALPS II) is a light-shining-through-a-wall (LSW) experiment based at DESY in Hamburg, Germany, that will search for axions and axion-like particles down to the coupling of the axion to two photons of $g_{a\gamma\gamma}$ >2$\times10^{-11}$ GeV$^{-1}$ for masses below 0.1 meV. ALPS II will use two strings of superconducting dipole magnets that are over one hundred meters in length, as well as optical cavities before and after the wall to boost the effective signal rate of the regenerated photons by more than 12 orders of magnitude when compared to previous generations of LSW experiments. Data taking with a simplified optical system is expected to begin in early 2023.

• Axion-like particle as cold dark matter via the misalignment mechanism with PQ symmetry unbroken during inflation

  Pawel Kozow, Marek Olechowski

  SciPost Phys. Proc. 12, 038 (2023) · published 4 July 2023 | Toggle abstract · pdf

  The QCD axion and axion-like particles (ALPs) are well motivated candidates for Cold Dark Matter (CDM). Such models may be divided into two classes depending on whether the associated Peccei-Quinn (PQ) symmetry is broken or not during inflation. The latter case is usually considered to be quite simple with relic density depending only on the corresponding decay constant and with no constraints from the known bounds on isocurvature perturbations. We will show that the situation is much more complicated. We will discuss conditions which should be fulfilled by ALP models with U(1) unbroken during inflation to be phenomenologically interesting.

• Constraints on heavy dark matter annihilation and decay from electron and positron cosmic ray spectra

  Holger Motz

  SciPost Phys. Proc. 12, 035 (2023) · published 4 July 2023 | Toggle abstract · pdf

  Annihilation or decay of dark matter (DM) could contribute to the electron and positron cosmic-ray flux, allowing for constraints on DM parameters from its measurement. CALET is directly measuring the energy spectrum of electron+positron cosmic rays up into the TeV region most important for studying heavy DM, while AMS-02 provides a positron-only spectrum below the TeV range. Limits on DM annihilation and decay well into the TeV mass range have been derived from a combined analysis of both data-sets with an astrophysical background model including pulsars as the origin of the positron excess and individual nearby supernova remnant sources.

• Dark matter or millisecond pulsars? A deep learning-based analysis of the Fermi Galactic Centre Excess

  Florian List, Nicholas L. Rodd, Geraint F. Lewis

  SciPost Phys. Proc. 12, 034 (2023) · published 4 July 2023 | Toggle abstract · pdf

  The $\gamma$-ray Galactic Centre Excess (GCE) remains one of the few observed high-energy signals for which a dark matter (DM) origin is a plausible explanation. We present a deep learning-based analysis of the $\gamma$-ray sky in the Galactic Centre region, carefully accounting for the mathematical degeneracy between faint point-sources (PSs) such as millisecond pulsars (MSPs) and DM-like Poisson emission. Using recent models for the Galactic foregrounds, we find that relatively few bright PSs just below Fermi's detection threshold seem unlikely to explain the GCE, although we continue to find evidence for PSs. Looking ahead, further improvements in the modelling of the $\gamma$-ray sky will be crucial for distinguishing between a DM-like and point-like morphology of the signal.

• remoTES: A new design for the cryogenic NaI detectors of the COSINUS experiment

  L. Einfalt, G. Angloher, Mukund Raghunath Bharadwaj, I. Dafinei, N. Di Marco, F. Ferroni, S. Fichtinger, A. Filipponi, T. Frank, M. Friedl, A. Fuss, Z. Ge, M. Heikinheimo, K. Huitu, M. Kellermann, R. Maji , M. Mancuso, L. Pagnanini, F. Petricca, S. Pirro, F. Pröbst, G. Profeta, A. Puiu, F. Reindl, K. Schäffner, J. Schieck, D. Schmiedmayer, C. Schwertner, M. Stahlberg, A. Stendahl, M. Stukel , F. Wagner, S. Yue, V. Zema, Y. Zhu

  SciPost Phys. Proc. 12, 033 (2023) · published 4 July 2023 | Toggle abstract · pdf

  The increasing statistical significance of the DAMA/LIBRA annual modulation signal is a cause for tension in the field of dark matter direct detection. The COSINUS experiment aims at a model-independent cross-check of the DAMA/LIBRA signal claim, using NaI crystals operated as cryogenic scintillating calorimeters at millikelvin temperatures. Such a setup enables measurement of phonon and scintillation light signals via Transition Edge Sensors (TESs) and allows particle discrimination on an event-by-event basis. The non-standard properties of NaI cause an obstacle when attaching a TES directly onto the surface of the crystal. This can be overcome with the ``remoTES'' design, where the TES is attached to an external wafer crystal. We present the results from a first successful operation of NaI and other crystals as cryogenic calorimeters with the remoTES design.

• Characterisation of low background CaWO$_4$ crystals for CRESST-III

  A. Kinast, G. Angloher, S. Banik, G. Benato, A. Bento, A. Bertolini, R. Breier, C. Bucci, J. Burkhart, L. Canonica, A. D'Addabbo, S. Di Lorenzo, L. Einfalt, A. Erb, F. v. Feilitzsch, N. Ferreiro Iachellini, S. Fichtinger, D. Fuchs, A. Fuss, A. Garai, V.M. Ghete, S. Gerster, P. Gorla, P.V. Guillaumon, S. Gupta, D. Hauff, M. Ješkovský, J. Jochum, M. Kaznacheeva, H. Kluck, H. Kraus, A. Langenkämper, M. Mancuso, L. Marini, L. Meyer, V. Mokina, A. Nilima, M. Olmi, T. Ortmann, C. Pagliarone, L. Pattavina, F. Petricca, W. Potzel, P. Povinec, F. Pröbst, F. Pucci, F. Reindl, J. Rothe, K. Schäffner, J. Schieck, D. Schmiedmayer, S. Schönert, C. Schwertner, M. Stahlberg, L. Stodolsky, C. Strandhagen, R. Strauss, I. Usherov, F. Wagner, M. Willers, V. Zema (CRESST Collaboration)

  SciPost Phys. Proc. 12, 031 (2023) · published 4 July 2023 | Toggle abstract · pdf

  The CRESST-III experiment aims at the direct detection of dark matter particles via their elastic scattering off nuclei in a scintillating CaWO$_4$ target crystal. For many years CaWO$_4$ crystals have successfully been produced in-house at Technische Universität München with a focus on high radiopurity. To further improve the CaWO$_4$ crystals, an extensive chemical purification of the raw materials has been performed and the crystal TUM93 was produced from this powder. We present results from an $\alpha$-decay rate analysis performed on 344 days of data collected in the ongoing CRESST-III data-taking campaign. The $\alpha$-decay rate could significantly be reduced.