Publications

Order by: publication date number of citations

• 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.

• 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.

• Measurements of Higgs boson properties in decays to two Tau leptons and search for lepton-flavor-violating Higgs boson decays into Tau leptons using the ATLAS detector

  Ömer Oğul Öncel

  SciPost Phys. Proc. 17, 013 (2025) · published 23 July 2025 | Toggle abstract · pdf

  Three analyses exploiting the $H→\tau\tau$ process using 139 fb$^{-1}$ of proton--proton collision data collected at a center-of-mass energy of 13 TeV by the ATLAS detector at the LHC are presented. A measurement of $VH$ production, with $V(=W, Z)→ e\nu/\mu\nu,ee/\mu\mu$ decays, has established the first evidence for this process with an observed (expected) significance of 4.2 (3.6) standard deviations. The second analysis, first of its kind by the ATLAS collaboration, probes CP-invariance if the decay products of the $\tau$ leptons using an angular observable $\phi_\tau$, and measured an observed (expected) value of $\phi_\tau=9 ± 16^\circ (0 ± 28^\circ)$ at 68% confidence level. The last analysis is a search for lepton-flavour-violation in $H→ e\tau/\mu\tau$ decays, where most stringent exclusion limits at 95% confidence level on $H→ e\tau$ branching ratio of 0.2%, is obtained.

• 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.

• Background suppression in the COSINUS experiment: Active muon veto and radiopure materials selection

  M. Stukel, G. Angloher, Mukund Raghunath Bharadwaj, I. Dafinei , N. Di Marco, L. Einfalt, 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, F. Wagner, S. Yue, V. Zema, Y. Zhu

  SciPost Phys. Proc. 12, 032 (2023) · published 4 July 2023 | Toggle abstract · pdf

  For over twenty-five years the DAMA/LIBRA experiment has reported an annual modulation signal that is consistent with a dark matter explanation. This signal is, currently, in tension with the null results observed by other searches that utilize different target detectors. The COSINUS experiment will perform a model-independent cross-check of the DAMA/LIBRA result by using the same target material, NaI crystals, operated as scintillating calorimeters. By measuring both temperature and light the NaI crystals in COSINUS will be able to distinguish between electron and nuclear recoils on an event-by-event basis. However, background events induced by cosmic-rays, environmental radioactivity or the intrinsic contamination of the materials used in the crystal, shielding and infrastructure can pose an issue to any analysis and must be fully understood. We report on the status of the development of the simulation for an active water Cherenkov muon veto, as well as the results of the beginning radiogenic material screening.

• Searches for lepton flavor violation in meson decays at Belle

  Sourav Patra

  SciPost Phys. Proc. 17, 009 (2025) · published 23 July 2025 | Toggle abstract · pdf

  We report the results of recent searches on charged lepton flavor violation using the $e^+e^-$ collision data collected by the Belle detector. In the first section, we present a search for the lepton-flavor-violating decays $B{}^0_s → \ell^{\mp}\tau^{±}$, where $\ell = e, \mu$, using $121\ \mathrm{fb}^{-1}$ data collected at the $\Upsilon(5S)$ resonance. We also search for the lepton-flavour-violating decays $B^+ \to K^+ \tau^± \ell^\mp$, with $\ell = (e, \mu)$, using $711\ \mathrm{fb}^{-1}$ $\Upsilon(4S)$ data sample. Finally, we present a search for the charged lepton-flavor-violating decays $\Upsilon(1S)→\ell^±\ell^{\prime\mp}$ and radiative charged lepton-flavour-violating decays $\Upsilon(1S)→\gamma\ell^±\ell^{\prime\mp}$ [$\ell,\ell^\prime = e, \mu, \tau$] using $25\ \mathrm{fb}^{-1}$ data recorded at $\Upsilon(2S)$ resonance. This search uses $\Upsilon(1S)$ mesons produced in $\Upsilon(2S)→\pi^+\pi^-\Upsilon(1S)$ transitions.

• The Scintillating Bubble Chamber Experiment

  Ben Broerman

  SciPost Phys. Proc. 12, 023 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The Scintillating Bubble Chamber (SBC) collaboration is combining the well-established liquid argon and bubble chamber technologies to search for low-mass, GeV-scale dark matter. Liquid-noble bubble chambers benefit from the excellent electron-recoil insensitivity inherent in bubble chambers with the addition of energy reconstruction provided from the scintillation signal for background rejection. The projected sensitivity with a quasi-background-free 10-kg-year exposure at a 100 eV nuclear recoil threshold is approximately 10$^{-43}$ cm$^2$ for a 1 GeV/c$^2$ dark matter mass.

• Anisotropic ionization threshold and directional sensitivity in solid state DM detectors

  Matti Heikinheimo, Sebastian Sassi, Kimmo Tuominen, Kai Nordlund, Nader Mirabolfathi

  SciPost Phys. Proc. 12, 020 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The threshold displacement energy for nuclear recoils depends strongly on the direction of the recoiling nucleus with respect to the crystal lattice. Assuming that similar dependence holds for the ionization threshold for low energy nuclear recoils, we explore the consequences of the resulting directional dependence of the observable event rate in ionization detectors. For low mass dark matter, this effect leads to a daily modulation in the event rate. We discuss how this effect can be utilized to separate the DM signal from the solar neutrino background and how the structure of the modulation signal can be used to identify the type of the DM-nucleon coupling.

• The CYGNO/INITIUM experiment

  F. D. Amaro, E. Baracchini, L. Benussi , S. Bianco, C. Capoccia, M. Caponero, D. Santos Cardoso, G. Cavoto, A. Cortez, I. A. Costa, E. Dané, G. Dho, F. Di Giambattista, E. Di Marco, G. D’Imperio, F. Iacoangeli, H. P. L. Jùnior, G. S. P. Lopes, G. Maccarrone, R. D. P. Mano, R. R. M. Gregorio, D. J. G. Marques, G. Mazzitelli, A. G. McLean, A. Messina, C. M. B. Monteiro, R. A. Nobrega, I. Fonseca Pains, E. Paoletti, L. Passamonti, S. Pelosi, F. Petrucci, S. Piacentini, D. Piccolo, D. Pierluigi, D. Pinci, A. Prajapati, F. Renga, R. J. C. Roque, F. Rosatelli, A. Russo, J. M. F. dos Santos, G. Saviano, N. J. C. Spooner, R. Tesauro, S. Tommasini, S. Torelli

  SciPost Phys. Proc. 12, 019 (2023) · published 3 July 2023 | Toggle abstract · pdf

  The CYGNO project for the development of a high precision optical readout gaseous TPC for directional Dark Matter search and solar neutrino spectroscopy will be presented. It is to be hosted at Laboratori Nazionali del Gran Sasso. CYGNO peculiar features are the use of sCMOS cameras and PMTs coupled to GEMs amplification of a helium-based gas mixture at atmospheric pressure, in order to achieve 3D tracking with head tail capability and background rejection down to O(keV) energy, to boost sensitivity to low WIMP masses. The latest R&D results within the CYGNO project will be discussed along with the underground installation and operation of a 50 l prototype, soon to be followed by a O(1) m3 experiment demonstrator in 2024-2026. The latest results on the negative ion drift operation at atmospheric pressure within CYGNO optical readout approach will be illustrated, which is the aim of the ERC Consolidator Grant project INITIUM.

• Neutron production in ($\alpha$,n) reactions in SOURCES4

  Vitaly A. Kudryavtsev, Piotr Krawczun, Rayna Bocheva

  SciPost Phys. Proc. 12, 018 (2023) · published 3 July 2023 | Toggle abstract · pdf

  Neutrons produced in spontaneous fission and ($\alpha,n$) reactions can induce background events in underground experiments looking for rare processes. A number of computer codes are available to calculate cross-sections of ($\alpha,n$) reactions, branching ratios to various states and neutron yields. SOURCES4 code has been used in this work to calculate neutron yields and energy spectra with input cross-sections and branching ratios taken from experimental data and models from EMPIRE2.19/3.2.3 and TALYS1.9 codes. A comparison of SOURCES4 calculations with experimental data from alpha beams and radioactive decay chains is presented.