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:20250110T182642Z UID:indico-contribution-338-1540@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Takuya Wada on behalf of the GAPS collaboration (Aoy ama Gakuin University)\nThe General Antiparticle Spectrometer (GAPS) is an international balloon-borne project for indirect dark matter (DM) searche s that investigates low-energy antinuclei in cosmic-ray\, especially undis covered antideuterons. Cosmic-ray antideuterons can be produced by self-an nihilation or decay of WIMP DM. The flux of DM-originated antideuterons ca n be orders of magnitude higher than that of the secondary (or background) component. Therefore\, antideuterons are considered to be a background-fr ee probe to search for DM. GAPS uses a unique concept to identify antinucl ei by applying the physics of exotic atom creation and decay. The GAPS ins trument is composed of lithium-drifted silicon (Si(Li)) detectors surround ed by a double-layered plastic scintillation-counter time-of-flight system . An incoming antinucleus forms an exotic atom in the Si(Li) detectors. Th rough the deexcitation and nuclear annihilation processes of the exotic at om\, characteristic X-rays and charged particles are emitted. By detecting and tracking those X-rays and particles\, GAPS has strong particle identi fication\, resulting in a high sensitivity for rare antinuclei. The first GAPS flight is scheduled for late 2021. We are currently developing all di fferent subsystems\, such as the Si(Li) tracker\, time-of-flight system\, cooling system\, and detailed simulation code of the instrument. We will r eport the scientific motivation\, detection concept\, and development stat us of GAPS.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/259/contributions/1 540/ 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:20250110T182642Z UID:indico-contribution-338-1541@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Daiki Hashimoto (Nagoya University)\nIn the context of the high energy astrophysics\, the nature of dark matter annihilation e xpected to emit gamma rays have been probed utilizing observed gamma-ray f lux in a direction of a high matter-density region. Recently\, some studie s have been performed with nearby dwarf galaxies or the Galactic center an d then the cross section for dark matter annihilation have been constraine d.\nIn our study\, we focus on Low Surface Brightness Galaxies (LSBGs) cat aloged by the observation data of Hyper Suprime-Cam (HSC). LSBGs can be us ed as novel tracers of dark matter annihilation signals because of being m ore massive than dwarf spheroids and having less astronomical contaminatio ns due to relatively quiescent states of those\, which can perform robuste r research for dark matter annihilation signals. \nWe model the gamma-ray flux from LSBGs using the 8 HSC-LSBGs measured each redshift\, and comperi ng with observed gamma-ray flux by Fermi Large Area Telescope\, provide th e upper limit of the cross section for dark matter annihilation. \nMoreove r\, we prospect the future constraint with soon-to-be-detected LSBGs by fu ture observation. In our poster presentation\, we report our method and re sults\, and also discuss the prospects for the future constraint.\n\nhttps ://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:20250110T182642Z UID:indico-contribution-338-1561@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Osamu Seto (Hokkaido University)\nWe propose models of a thermal relic DM with the present annihilation cross-section being ve ry suppressed. This property can be realized in an extra U(1) gauge intera cting 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 r egions. We also discuss various implication to future DM detection experim ents\, the DM interpretation of the gamma ray excess in the globular clust er 47 Tucanae\, the muon anomalous magnetic moment\, the Hubble Tension an d others.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/259/contributions/156 1/ 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:20250110T182642Z UID:indico-contribution-338-1560@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Oscar Macias ()\nWe set conservative constraints on decaying dark matter particles with masses spanning a very wide range ($10 ^4-10^{16}$ GeV). For this we use multimessenger observations of cosmic-ra y (CR) protons/antiprotons\, electrons/positrons\, neutrinos/antineutrinos and gamma rays. Focusing on decays into the $b\\bar{b}$ channel\, we simu late the spectra of dark matter yields by using the Dokshitzer-Gribov-Lipa tov-Altarelli-Parisi equations and the Pythia package. We then propagate t he CRs of dark matter origin till Earth by using the state-of-the-art nume rical frameworks CRPropa\, GALPROP and HelMod for the solution of the CR t ransport equation in the extragalactic\, Galactic region and the heliosphe re\, respectively. Conservative limits are obtained by requiring that the predicted dark matter spectra at Earth be less than the observed CR spectr a. Overall\, we exclude dark matter lifetimes of $10^{28}$ s or shorter fo r all the masses investigated in this work. The most stringent constraints reach $10^{30}$ s for very heavy dark matter particles with masses in the range $10^{11}−10^{14}$ GeV.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event /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:20250110T182642Z UID:indico-contribution-338-1564@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Masao Mori (University of Tsukuba)\nCold dark matter (CDM) cosmology is the standard paradigm of structure formation in the un iverse. However\, it has several unsolved severe problems. The missing sat ellites problem refers to the overabundance of theoretically predicted CDM subhalos compared to observed satellite galaxies in the Local Group. The most popular interpretation is that the small dark matter halos have extre mely inefficient star-forming history. In this study\, we investigate the possible existence of the stellar deficient CDM halos using large scale nu merical simulations for galaxy collisions between a CDM subhalo and a dwar f galaxy in the Local Group.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/25 9/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:20250110T182642Z UID:indico-contribution-338-1559@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Shunichi Horigome (Kavli IPMU)\nDwarf spheroidal gal axies (dSphs) are promising targets for indirect detection experiments sin ce they contain a large amount of dark matter (DM). For the precise calcul ation of the amount of annihilation signal flux from dSph\, we must know t he DM mass density distribution of target dSphs\, estimated from the obser vation of the stellar motion.\nIn the DM profile estimation\, the major un certainty of DM profile comes from the foreground contamination of the Mil ky Way stars in front of dSph. In the conventional analyses\, the contamin ated stars are partially removed based on their membership probability est imated by a clustering technique called EM algorithm. However\, even if we use this technique\, some contaminated stars still remain in the data set \, which leads to the incorrect sensitivity of indirect detection experime nts.\nIn this work\, we adopt a new method to deal with the contamination effect based on the mixture model of the dSph member and foreground stars. \nUsing this method\, we estimate the DM density profile of Draco\, Sculpt or\, and Ursa Minor\, the top three DM rich dSphs\, with reliable errorbar s properly including the uncertainty of the contamination effect.\n\nhttps ://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:20250110T182642Z UID:indico-contribution-338-1569@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Kazuki Kato (University of Tsukuba)\nThe lambda cold dark matter model is the standard paradigm of structure formation in the universe. However\, there is a discrepancy known as the “cusp–core pro blem” in the mass–density distribution of a dark matter halo (DMH) bet ween theory and observation. We investigate the dynamical response of DMHs to recurrent starbursts on the formation of less massive galaxies to solv e this issue. In the early epoch of the galaxy formation\, the cycle of ex pansion and contraction of the interstellar gas driven by the stellar feed backs leads to a recursive change in the gravitational potential of the ga s. The eccentricity of the DMH particles around the centre becomes large b y this change. Then\, the system expands\, and the core scale increases du e to the oscillation process. Finally\, the DMH then reaches the new quasi -equilibrium state. Our simulation shows that the energy transport by the overtone components contained in the periodic oscillation of the potential change strongly influences the inner slope of the mass–density profile of the DMH. We conclude that the resonance between DMH particles and the d ensity wave excited by the oscillating potential plays a crucial role in u nderstanding the physical mechanism of the cusp–to–core transition of 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:20250110T182642Z UID:indico-contribution-338-1571@indico.icrr.u-tokyo.ac.jp DESCRIPTION:Speakers: Kosuke Ozaki (Nagoya University)\nIn the last three decades\, numerous terrestrial experiments have been built to detect the f aint interactions between WIMP dark matter and ordinary matter. Among them \, experiments using dual-phase xenon time projection chambers (TPCs) are leading the search especially for high mass WIMPs. In these experiments\, photomultipliers (PMTs) are used to detect the prompt primary scintillatio n and secondary electro-luminescence of ionized electrons. However\, PMTs have several important shortcomings: the residual radioactivity levels\, c ost\, bulkiness\, and stability at cryogenic conditions. Therefore\, sever al alternative technologies are under consideration toward the future dark matter experiments using ~50 tons of liquid xenon (LXe). One of the such technologies is silicon photomultipliers (SiPMs). SiPM has very low radioa ctivity\, compact geometry\, low operation voltages and reasonable photo-d etection efficiency for VUV light. However\, current SiPM still has ~two o rder of magnitude higher dark count rate compared with PMT\, which signifi cantly increases accidental coincidence background. In order to solve thes e problems\, we are currently developing a new SiPM with the help of Hamam atsu and FBK. In this poster\, we will report the current status of the p erformance measurements of the Hamamatsu VUV4 SiPMs (3mm×3mm)\, new SiPMs with less dark count and FBK VUV SiPMs (6mm×6mm).\n\nhttps://indico.icrr .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