BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:The GAPS experiment: sensitive survey of cosmic-ray antinuclei to search dark matter DTSTART;VALUE=DATE-TIME:20191112T030000Z DTEND;VALUE=DATE-TIME:20191112T030100Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-23@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Wada on behalf of the GAPS collaboration\, Takuya (A oyama Gakuin University)\nThe General Antiparticle Spectrometer (GAPS) is an international balloon-borne project for indirect dark matter (DM) searc hes that investigates low-energy antinuclei in cosmic-ray\, especially und iscovered antideuterons. Cosmic-ray antideuterons can be produced by self- annihilation or decay of WIMP DM. The flux of DM-originated antideuterons can be orders of magnitude higher than that of the secondary (or backgroun d) component. Therefore\, antideuterons are considered to be a background- free probe to search for DM. GAPS uses a unique concept to identify antinu clei by applying the physics of exotic atom creation and decay. The GAPS i nstrument is composed of lithium-drifted silicon (Si(Li)) detectors surrou nded by a double-layered plastic scintillation-counter time-of-flight syst em. An incoming antinucleus forms an exotic atom in the Si(Li) detectors. Through the deexcitation and nuclear annihilation processes of the exotic atom\, characteristic X-rays and charged particles are emitted. By detecti ng and tracking those X-rays and particles\, GAPS has strong particle iden tification\, resulting in a high sensitivity for rare antinuclei. The firs t GAPS flight is scheduled for late 2021. We are currently developing all different subsystems\, such as the Si(Li) tracker\, time-of-flight system\ , cooling system\, and detailed simulation code of the instrument. We will report the scientific motivation\, detection concept\, and development st atus of GAPS.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/259/contributions /1540/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1540/ END:VEVENT BEGIN:VEVENT SUMMARY:Constraint on the nature of annihilating dark matter with Low Surf ace Brightness Galaxies DTSTART;VALUE=DATE-TIME:20191112T030600Z DTEND;VALUE=DATE-TIME:20191112T030700Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-51@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Hashimoto\, Daiki (Nagoya University)\nIn the contex t of the high energy astrophysics\, the nature of dark matter annihilation expected to emit gamma rays have been probed utilizing observed gamma-ray flux in a direction of a high matter-density region. Recently\, some stud ies have been performed with nearby dwarf galaxies or the Galactic center and then the cross section for dark matter annihilation have been constrai ned.\nIn our study\, we focus on Low Surface Brightness Galaxies (LSBGs) c ataloged by the observation data of Hyper Suprime-Cam (HSC). LSBGs can be used as novel tracers of dark matter annihilation signals because of being more massive than dwarf spheroids and having less astronomical contaminat ions due to relatively quiescent states of those\, which can perform robus ter research for dark matter annihilation signals. \nWe model the gamma-ra y flux from LSBGs using the 8 HSC-LSBGs measured each redshift\, and compe ring with observed gamma-ray flux by Fermi Large Area Telescope\, provide the upper limit of the cross section for dark matter annihilation. \nMoreo ver\, we prospect the future constraint with soon-to-be-detected LSBGs by future observation. In our poster presentation\, we report our method and results\, and also discuss the prospects for the future constraint.\n\nhtt ps://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1541/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1541/ END:VEVENT BEGIN:VEVENT SUMMARY:Scalar dark matter interacting through an extra U (1) gauge intera ction DTSTART;VALUE=DATE-TIME:20191112T030300Z DTEND;VALUE=DATE-TIME:20191112T030400Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-35@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Seto\, Osamu (Hokkaido University)\nWe propose model s of a thermal relic DM with the present annihilation cross-section being very suppressed. This property can be realized in an extra U(1) gauge inte racting complex scalar DM. We consider scalar dark matter in U(1)B−L\,U( 1)(B−L)3 and U(1)Lμ−Lτ extended models and identify viable parameter regions. We also discuss various implication to future DM detection exper iments\, the DM interpretation of the gamma ray excess in the globular clu ster 47 Tucanae\, the muon anomalous magnetic moment\, the Hubble Tension and others.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1 561/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1561/ END:VEVENT BEGIN:VEVENT SUMMARY:Probing heavy dark matter decays with multi-messenger astrophysica l data DTSTART;VALUE=DATE-TIME:20191112T031200Z DTEND;VALUE=DATE-TIME:20191112T031300Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-63@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Macias\, Oscar ()\nWe set conservative constraints o n decaying dark matter particles with masses spanning a very wide range ($ 10^4-10^{16}$ GeV). For this we use multimessenger observations of cosmic- ray (CR) protons/antiprotons\, electrons/positrons\, neutrinos/antineutrin os and gamma rays. Focusing on decays into the $b\\bar{b}$ channel\, we si mulate the spectra of dark matter yields by using the Dokshitzer-Gribov-Li patov-Altarelli-Parisi equations and the Pythia package. We then propagate the CRs of dark matter origin till Earth by using the state-of-the-art nu merical frameworks CRPropa\, GALPROP and HelMod for the solution of the CR transport equation in the extragalactic\, Galactic region and the heliosp here\, respectively. Conservative limits are obtained by requiring that th e predicted dark matter spectra at Earth be less than the observed CR spec tra. Overall\, we exclude dark matter lifetimes of $10^{28}$ s or shorter for all the masses investigated in this work. The most stringent constrain ts reach $10^{30}$ s for very heavy dark matter particles with masses in t he range $10^{11}−10^{14}$ GeV.\n\nhttps://indico.icrr.u-tokyo.ac.jp/eve nt/259/contributions/1560/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1560/ END:VEVENT BEGIN:VEVENT SUMMARY:Galaxy collisions and the missing satellite problem in the cold da rk matter model DTSTART;VALUE=DATE-TIME:20191112T031500Z DTEND;VALUE=DATE-TIME:20191112T031600Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-71@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Mori\, Masao (University of Tsukuba)\nCold dark matt er (CDM) cosmology is the standard paradigm of structure formation in the universe. However\, it has several unsolved severe problems. The missing s atellites problem refers to the overabundance of theoretically predicted C DM subhalos compared to observed satellite galaxies in the Local Group. Th e most popular interpretation is that the small dark matter halos have ext remely inefficient star-forming history. In this study\, we investigate th e possible existence of the stellar deficient CDM halos using large scale numerical simulations for galaxy collisions between a CDM subhalo and a dw arf galaxy in the Local Group.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/ 259/contributions/1564/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1564/ END:VEVENT BEGIN:VEVENT SUMMARY:J-factor estimation of Draco\, Sculptor and Ursa Minor dSphs with the member/foreground mixture model DTSTART;VALUE=DATE-TIME:20191112T030900Z DTEND;VALUE=DATE-TIME:20191112T031000Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-59@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Horigome\, Shunichi (Kavli IPMU)\nDwarf spheroidal g alaxies (dSphs) are promising targets for indirect detection experiments s ince they contain a large amount of dark matter (DM). For the precise calc ulation of the amount of annihilation signal flux from dSph\, we must know the DM mass density distribution of target dSphs\, estimated from the obs ervation of the stellar motion.\nIn the DM profile estimation\, the major uncertainty of DM profile comes from the foreground contamination of the M ilky Way stars in front of dSph. In the conventional analyses\, the contam inated stars are partially removed based on their membership probability e stimated by a clustering technique called EM algorithm. However\, even if we use this technique\, some contaminated stars still remain in the data s et\, which leads to the incorrect sensitivity of indirect detection experi ments.\nIn this work\, we adopt a new method to deal with the contaminatio n effect based on the mixture model of the dSph member and foreground star s.\nUsing this method\, we estimate the DM density profile of Draco\, Scul ptor\, and Ursa Minor\, the top three DM rich dSphs\, with reliable errorb ars properly including the uncertainty of the contamination effect.\n\nhtt ps://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1559/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1559/ END:VEVENT BEGIN:VEVENT SUMMARY:Dynamics of the cusp-to-core transformation in the cold dark matte r halos DTSTART;VALUE=DATE-TIME:20191112T031800Z DTEND;VALUE=DATE-TIME:20191112T031900Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-74@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Kato\, Kazuki (University of Tsukuba)\nThe lambda co ld dark matter model is the standard paradigm of structure formation in th e universe. However\, there is a discrepancy known as the “cusp–core p roblem” in the mass–density distribution of a dark matter halo (DMH) b etween theory and observation. We investigate the dynamical response of DM Hs to recurrent starbursts on the formation of less massive galaxies to so lve this issue. In the early epoch of the galaxy formation\, the cycle of expansion and contraction of the interstellar gas driven by the stellar fe edbacks leads to a recursive change in the gravitational potential of the gas. The eccentricity of the DMH particles around the centre becomes large by this change. Then\, the system expands\, and the core scale increases due to the oscillation process. Finally\, the DMH then reaches the new qua si-equilibrium state. Our simulation shows that the energy transport by th e overtone components contained in the periodic oscillation of the potenti al change strongly influences the inner slope of the mass–density profil e of the DMH. We conclude that the resonance between DMH particles and the density wave excited by the oscillating potential plays a crucial role in understanding the physical mechanism of the cusp–to–core transition o f DMHs.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1569/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1569/ END:VEVENT BEGIN:VEVENT SUMMARY:Characterization of new photo-detectors for the future dark matter experiments with liquid xenon DTSTART;VALUE=DATE-TIME:20191112T032100Z DTEND;VALUE=DATE-TIME:20191112T032200Z DTSTAMP;VALUE=DATE-TIME:20250110T182643Z UID:indico-contribution-432-75@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Ozaki\, Kosuke (Nagoya University)\nIn the last thre e decades\, numerous terrestrial experiments have been built to detect the faint interactions between WIMP dark matter and ordinary matter. Among th em\, experiments using dual-phase xenon time projection chambers (TPCs) ar e leading the search especially for high mass WIMPs. In these experiments\ , photomultipliers (PMTs) are used to detect the prompt primary scintillat ion and secondary electro-luminescence of ionized electrons. However\, PMT s have several important shortcomings: the residual radioactivity levels\, cost\, bulkiness\, and stability at cryogenic conditions. Therefore\, sev eral alternative technologies are under consideration toward the future da rk matter experiments using ~50 tons of liquid xenon (LXe). One of the suc h technologies is silicon photomultipliers (SiPMs). SiPM has very low radi oactivity\, compact geometry\, low operation voltages and reasonable photo -detection efficiency for VUV light. However\, current SiPM still has ~two order of magnitude higher dark count rate compared with PMT\, which signi ficantly increases accidental coincidence background. In order to solve th ese problems\, we are currently developing a new SiPM with the help of Ham amatsu and FBK. In this poster\, we will report the current status of the performance measurements of the Hamamatsu VUV4 SiPMs (3mm×3mm)\, new SiP Ms with less dark count and FBK VUV SiPMs (6mm×6mm).\n\nhttps://indico.ic rr.u-tokyo.ac.jp/event/259/contributions/1571/ LOCATION:The University of Tokyo\, Kashiwa Campus URL:https://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1571/ END:VEVENT END:VCALENDAR