Browsing by Author "Lee, Fei-Fan"

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Constraining dark matter capture and annihilation cross sections by searching for neutrino signature from the Earth's core
(2014-01-06)
Lee, Fei-Fan
;
Lin, Guey-Lin
;
Tsai, Yue-Lin Sming
;
物理研究所
;
Institute of Physics
We study the sensitivity of IceCube/DeepCore detector to dark matter annihilations in the Earth's core. We focus on annihilation modes chi chi -> nu(nu) over cap, tau(+)tau(-), h (h) over cap, and W+W-. Both track and cascade events are considered in our analysis. By fixing the dark matter annihilation cross section at some nominal values, we study the sensitivity of the IceCube/DeepCore detector to dark matter spin- independent cross section sigma(SI)(p) for m(chi) ranging from few tens of GeV to 10 TeV. This sensitivity is compared with the existing IceCube 79-string constraint on the same cross section, which was obtained by searching for dark matter annihilations in the Sun. We compare this sensitivity to dark matter direct detection results as well, in particular the XENON100 (2012) limit and the parameter regions preferred by DAMA and CRESST- II experiments. We also present IceCube/DeepCore sensitivity to hs.i as a function of m(chi) by fixing sigma(SI)(p) at XENON100 (2012) and XENON1T limits, respectively. This sensitivity is compared with the preferred dark matter parameter range derived from the combined fitting to PAMELA and AMS02 positron fraction data. We conclude that the search for dark matter annihilations in the Earth's core provides competitive constraints on sigma(SI)(p) and in the case of low- mass dark matter. Particularly, the expected constraint on sigma(SI)(p) for 5 years of data taking in IceCube/DeepCore is more stringent than the current IceCube 79- string limit mentioned above.
Dark Matter Induced Neutrino Signature in IceCube DeepCore Detector
(2014-01-01)
Lee, Fei-Fan
;
Lin, Guey-Lin
;
Tsai, Yue-Lin Sming
;
物理研究所
;
Institute of Physics
The installation of DeepCore array significantly lowers IceCube\'s energy threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos from annihilations and decays of light dark matter. To match this experimental development, we discuss decays of the event rate in DeepCore array due to neutrino flux produced by annihilations and galactic dark matter. This event rate is calculated with a 10 GeV threshold energy, which is smaller than the threshold energy taken in previous works. Taking into account the background event rate due to the atmospheric neutrino flux, we evaluate the sensitivity of DeepCore array for probing dark matter annihilation cross section and decay time. We compare our results with corresponding constraints derived from observations of WMAP, ACT and Fermi-LAT.
On possibility of determining neutrino mass hierarchy by the charged-current and neutral-current events of supernova neutrinos in scintillation detectors
(2019-02-12)
Lee, Fei-Fan
;
Lee, Feng-Shiuh
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Lai, Kwang-Chang
;
電機學院
;
College of Electrical and Computer Engineering
One of the unresolved mysteries in neutrino physics is the neutrino mass hierarchy. We present a new method to determine neutrino mass hierarchy by comparing the events of inverse beta decays (IBD), e+pn+e+, and neutral current (NC) interactions, ()+p()+p, of supernova neutrinos from accretion and cooling phases in scintillation detectors. Supernova neutrino flavor conversions depend on the neutrino mass hierarchy. On account of Mikheyev-Smirnov-Wolfenstein effects, the full swap of the e flux with the x (,) one occurs in the inverted hierarchy, while such a swap does not occur in the normal hierarchy. In consequence, the ratio of high energy IBD events to NC events for the inverted hierarchy is higher than in the normal hierarchy. Since the luminosity ofe is larger than that of x in accretion phase while the luminosity of e becomes smaller than that of x in cooling phase, we calculate this ratio for both accretion and cooling phases. By analyzing the change of this event ratio from accretion phase to cooling phase, one can determine the neutrino mass hierarchy.
Probing annihilations and decays of low-mass galactic dark matter in IceCube DeepCore array: Track events
(2012-01-25)
Lee, Fei-Fan
;
Lin, Guey-Lin
;
物理研究所
;
Institute of Physics
The deployment of DeepCore array significantly lowers IceCube's energy threshold to about 10 GeV and enhances the sensitivity of detecting neutrinos from annihilations and decays of light dark matter. To match this experimental development, we calculate the track event rate in DeepCore array due to neutrino flux produced by annihilations and decays of galactic dark matter. We also calculate the background event rate due to the atmospheric neutrino flux for evaluating the sensitivity of DeepCore array to galactic dark matter signatures. Unlike previous approaches, which set the energy threshold for track events at around 50 GeV (this choice avoids the necessity of including the oscillation effect in the estimation of atmospheric background event rate), we have set the energy threshold at 10 GeV to take full advantage of DeepCore array. We compare our calculated sensitivity with those obtained by setting the threshold energy at 50 GeV. We conclude that our proposed threshold energy significantly improves the sensitivity of DeepCore array to the dark matter signature for m (chi) < 100 GeV in the annihilation scenario and m (chi) < 300 GeV in the decay scenario.
Probing dark matter self-interaction in the Sun with IceCube-PINGU
(2014-10-01)
Chen, Chian-Shu
;
Lee, Fei-Fan
;
Lin, Guey-Lin
;
Lin, Yen-Hsun
;
物理研究所
We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 similar to 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube-PINGU using the annihilation channels chi chi -> tau(+)tau(-), nu(nu) over bar as examples. The PINGU sensitivities to DM self-interaction cross section sigma(chi chi) are estimated for track and cascade events.
Probing neutrino mass hierarchy by comparing the charged-current and neutral-current interaction rates of supernova neutrinos
(2016-07)
Lai, Kwang-Chang
;
Lee, Fei-Fan
;
Lee, Feng-Shiuh
;
Lin, Guey-Lin
;
Liu, Tsung-Che
The neutrino mass hierarchy is one of the neutrino fundamental properties yet to be determined. We introduce a method to determine neutrino mass hierarchy by comparing the interaction rate of neutral current (NC) interactions, nu((nu) over bar)+p -> v((v) over bar) +p, and inverse beta decays (IBD), (nu) over bar (e)+p -> n + e(+), of supernova neutrinos in scintillation detectors. Neutrino flavor conversions inside the supernova are sensitive to neutrino mass hierarchy. Due to Mikheyev-Smirnov-Wolfenstein effects, the full swapping of (nu) over bar (e) flux with the (nu) over bar (x)(x = mu, tau) one occurs in the inverted hierarchy, while such a swapping does not occur in the normal hierarchy. As a result, more high energy IBD events occur in the detector for the inverted hierarchy than the high energy IBD events in the normal hierarchy. By comparing IBD interaction rate with the mass hierarchy independent NC interaction rate, one can determine the neutrino mass hierarchy.
Probing the coupling of heavy dark matter to nucleons by detecting neutrino signature from the Earth's core
(2015-02-05)
Lin, Guey-Lin
;
Lin, Yen-Hsun
;
Lee, Fei-Fan
;
物理研究所
;
Institute of Physics
We argue that the detection of the neutrino signature from the Earth's core can effectively probe the coupling of heavy dark matter (m(chi) > 10(4) GeV) to nucleons. We first note that direct searches for dark matter (DM) in such a mass range provide much less stringent constraint than the constraint provided by such searches for m(chi) similar to 100 GeV. Furthermore, the energies of neutrinos arising from DM annihilation inside the Sun cannot exceed a few TeVs at the Sun's surface due to the attenuation effect. Therefore, the sensitivity to the heavy DM coupling is lost. Finally, the detection of the neutrino signature from the Galactic halo can only probe DM annihilation cross sections. We present neutrino event rates in IceCube and KM3NeT arising from the neutrino flux produced by annihilation of Earth-captured DM heavier than 10(4) GeV. The IceCube and KM3NeT sensitivities to spin-independent DM-proton scattering cross section sigma(chi p) in this mass range are presented for both isospin-symmetric and isospin-violating cases.
Sensitivities of the IceCube DeepCore detector to signatures of low-mass dark matter in the Galactic halo
(2013-01-02)
Lee, Fei-Fan
;
Lin, Guey-Lin
;
Tsai, Yue-Lin Sming
;
物理研究所
;
Institute of Physics
We discuss the event rate in the DeepCore array due to neutrino flux produced by annihilations and decays of Galactic dark matter. This event rate is calculated with a 10 GeV threshold energy, which is smaller than the threshold energy taken in previous works. Taking into account the background event rate due to the atmospheric neutrino flux, we evaluate the sensitivity of the DeepCore array for probing the dark matter annihilation cross section and decay time. The sensitivity studies include the annihilation modes chi chi -> b (b) over bar, tau(+)tau(-), mu(+)mu(-), and nu(nu) over bar, and decay modes chi -> b (b) over bar, tau(+)tau(-), mu(+)mu(-), and nu(nu) over bar. We compare our results with corresponding constraints derived from observations of WMAP, ACT, and Fermi-LAT. DOI: 10.1103/PhysRevD.87.025003
The Dark Matter Self-Interaction and Its Impact on the Critical Mass for Dark Matter Evaporations Inside the Sun
(2016-04-06)
Chen, Chian-Shu
;
Lee, Fei-Fan
;
Lin, Guey-Lin
;
Lin, Yen-Hsun
;
物理研究所
We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 similar to 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube-PINGU using the annihilation channels chi chi -> tau(+)tau(-), nu(nu) over bar as examples. The PINGU sensitivities to DM self-interaction cross section sigma(chi chi) are estimated for track and cascade events.
The Dark Matter Self-Interaction and Its Impact on the Critical Mass for Dark Matter Evaporations Inside the Sun
(2016-04-01)
Chen, Chian-Shu
;
Lee, Fei-Fan
;
Lin, Guey-Lin
;
Lin, Yen-Hsun
;
物理研究所
We study the capture, annihilation and evaporation of dark matter (DM) inside the Sun. It has been shown that the DM self-interaction can increase the DM number inside the Sun. We demonstrate that this enhancement becomes more significant in the regime of small DM mass, given a fixed DM self-interaction cross section. This leads to the enhancement of neutrino flux from DM annihilation. On the other hand, for DM mass as low as as a few GeVs, not only the DM-nuclei scatterings can cause the DM evaporation, DM self-interaction also provides non-negligible contributions to this effect. Consequently, the critical mass for DM evaporation (typically 3 similar to 4 GeV without the DM self-interaction) can be slightly increased. We discuss the prospect of detecting DM self-interaction in IceCube-PINGU using the annihilation channels chi chi -> tau(+)tau(-), nu(nu) over bar as examples. The PINGU sensitivities to DM self-interaction cross section sigma(chi chi) are estimated for track and cascade events.