A5028275942- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Neutrino Physics Research
- Cosmology and Gravitation Theories
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Galaxies: Formation, Evolution, Phenomena
- Black Holes and Theoretical Physics
- Atomic and Subatomic Physics Research
- Quantum Mechanics and Applications
- Quantum Chromodynamics and Particle Interactions
- Quantum chaos and dynamical systems
- Physics of Superconductivity and Magnetism
- Computational Physics and Python Applications
- Scientific Research and Discoveries
- Mathematical Dynamics and Fractals
- Statistical Mechanics and Entropy
- Noncommutative and Quantum Gravity Theories
Institute of Physics, Academia Sinica
2014-2019
National Taiwan University
2011-2016
University of Illinois Chicago
2014
University of California, Irvine
2007-2009
Aarhus University
2005-2007
Deutsches Elektronen-Synchrotron DESY
2002-2006
University of Southern Denmark
2005
Max Planck Institute for Nuclear Physics
2001
Can dark matter be stabilized by charge conservation, just as the electron is in standard model? We examine possibility that hidden, is, neutral under all model gauge interactions, but charged an exact {\rm U}(1) symmetry of hidden sector. Such candidates are predicted WIMPless models, supersymmetric models which has desired thermal relic density for a wide range masses. Hidden many novel properties not shared matter: (1) bound state formation and Sommerfeld-enhanced annihilation after...
The Fisher matrix formalism has in recent times become the standard method for predicting precision with which various cosmological parameters can be extracted from future data. This approach is fast and generally returns accurate estimates parameter errors when individual likelihoods approximate a Gaussian distribution. However, where Gaussianity not respected (due, instance, to strong degeneracies), loses its reliability. In this paper, we compare results of those Monte Carlo simulations....
Dark matter may be hidden, with no standard model gauge interactions. At the same time, in WIMPless models (WIMP: weakly interacting massive particles) hidden masses proportional to couplings squared, dark matter's thermal relic density naturally right range, preserving key quantitative virtue of WIMPs. We consider this possibility detail. first determine model-independent constraints on sectors from big bang nucleosynthesis and cosmic microwave background. Contrary conventional wisdom,...
In scenarios with extra dimensions and TeV-scale quantum gravity, black holes are expected to be produced copiously at center-of-mass energies above the fundamental Planck scale. The Large Hadron Collider (LHC) may thus turn into a factory of holes, which their production evaporation studied in detail. But even before LHC starts operating, Pierre Auger Observatory for cosmic rays, presently under construction, has an opportunity search hole signatures. Black scattering ultrahigh energy...
We have studied bounds on the neutrino mass using new data from WMAP 3 year data, Sloan Digital Sky Survey measurement of baryon acoustic (BAO) peak, Type Ia supernovae SNLS, and Lyman-α forest. find that even in most general models with a running spectral index where number neutrinos dark energy equation state are allowed to vary, 95% confidence limit (C.L.) bound sum masses is eV (95% C.L.), which we believe be robust. In more often used constrained analysis Nν = 3, w −1, αs 0, 0.48...
Surveys of weak gravitational lensing distant galaxies will be one the key cosmological probes in future. We study ability such surveys to constrain neutrino masses and equation state parameter dark energy, focusing on how tomographic information can improve sensitivity these parameters. also provide a detailed discussion systematic effects pertinent surveys, possible degradation parameters due effects. For future as Large Synoptic Survey Telescope survey, we find that, when combined with...
We propose a new constraint on light (sub-GeV) particles beyond the Standard Model that can be produced inside protoneutron star core resulting from core-collapse supernova explosion. It is derived by demanding energy carried exotic being transferred to progenitor stellar envelopes not exceed explosion of $\ensuremath{\lesssim}\text{ }2\ifmmode\times\else\texttimes\fi{}{10}^{51}\text{ }\text{ }\mathrm{erg}$ observed supernovae. show specifically for case dark photon which kinetically mixes...
Under the assumption that some part of observed highest energy cosmic rays consists protons originating from cosmological distances, we derive bounds on associated flux neutrinos generated by inelastic processes with microwave background photons. We exploit two methods. First, a power-like injection spectrum is assumed. Then, model-independent technique, based inversion proton flux, presented. The inferred lower bound quite robust. As expected, upper depends unknown composition rays. Our...
If the diffuse extragalactic gamma ray emission traces large scale structures of universe, peculiar anisotropy patterns are expected in sky. In particular, because cutoff distance introduced by absorption 0.1-10 TeV photons on infrared/optical background, prominent correlations with local within a range few hundreds Mpc should be present. We provide detailed predictions signal based PSCz map universe. also use mock N-body catalogues complemented halo model to study some statistical features...
In unparticle physics, operators of the conformal sector have self-interactions, and these are unsuppressed for strong coupling. The 3-point interactions completely determined by symmetry, up to a constant. We do not know any theoretical upper bounds on this Imposing current experimental constraints, we find that mediate spectacular collider signals, such as...
We propose a scenario in which simple power-like primary spectrum for protons with sources at cosmological distances leads to quantitative description of all the details observed cosmic ray energies from 1017 eV 1021 eV. As usual, ultrahigh energy above EGZK≈4×1019 loose large fraction their by photoproduction pions on microwave background, finally decay mainly into neutrinos. In our scenario, these so-called cosmogenic neutrinos interact nucleons atmosphere through Standard Model...
Recently, Weinberg proposed a scenario where Goldstone bosons may be masquerading as fractional cosmic neutrinos. We calculate the energy loss rates through emission of these in post-collapse supernova core. Invoking well established emissivity bound from Supernova 1987A observations and simulations, we find that nuclear bremsstrahlung processes can notably impose on boson coupling to Standard Model Higgs, $g$, dependent mass associated radial field, $m_r$. For $m_r$ large enough compared...
We study the difference between thermally produced fermionic and bosonic hot dark matter in detail. In linear regime of structure formation, their distinct free-streaming behaviours can lead to pronounced differences power spectrum. While not detectable with current cosmological data, such will be clearly observable upcoming large scale weak lensing surveys for particles as light mHDM∼0.2 eV. nonlinear regime, is subject same phase space constraints that severely limit amount infall into...
Extraterrestrial neutrinos can initiate deeply developing air showers, and those that traverse the atmosphere unscathed may produce cascades in ice or water. Up to now, no such events have been observed. This be translated into upper limits on diffuse neutrino flux. On other hand, observation of cosmic rays with primary energies >1010 GeV suggests there is a guaranteed flux cosmogenic neutrinos, arising from decay charged pions (and their muon daughters) produced proton interactions...
The observed burst duration and energies of the neutrinos from Supernova 1987A strongly limit possibility any weakly-interacting light particle species being produced in proto-neutron star (PNS) core leading to efficient energy loss. We reexamine this constraint on Weinberg’s Higgs portal model, which dark radiation particles (the Goldstone bosons) matter candidate (a Majorana fermion) interact with Standard Model (SM) fields solely through mixing SM boson a boson. In order for bosons freely...
Recently, Weinberg proposed a Higgs portal model with spontaneously broken global U(1) symmetry in which Goldstone bosons may be masquerading as fractional cosmic neutrinos. We extend the by gauging symmetry. This gives rise to so-called dark photon and Higgs. The photons can constitute about 0.912 (0.167) effective number of light neutrino species if they decouple from thermal bath before pions become non-relativistic after (before) QCD transition. Restriction on parameter space coupling...
Gamma-ray bursts (GRBs) are the most energetic explosion events in universe. An amount of gravitational energy order rest-mass Sun is released from a small region within short time. This should lead to formation fireball temperature MeV range, consisting electrons/positrons, photons, and fraction baryons. We exploit potential GRB fireballs for being laboratory testing particle physics beyond Standard Model, where we find that Weinberg's Higgs portal model serves as good candidate this...
We investigate the contribution of minimal supersymmetric extension standard model Higgs bosons produced in neutralino annihilation Earth and Sun to total weakly interacting massive particles detection signal. find that this is important results a lower bound for muon flux from ${10}^{\ensuremath{-}7}--{10}^{\ensuremath{-}8} {\mathrm{m}}^{\ensuremath{-}2} {\mathrm{yr}}^{\ensuremath{-}1}$ neutralinos heavier than about 200 GeV. notice due SUSY charged one can expect an energetic...
Models with extra spatial dimensions and TeV-scale gravity offer the first opportunity to test conjecture of black hole formation in trans-Planckian energy scattering small impact parameters. After a brief review gravitational at ultrahigh energies scenarios gravity, search strategies LHC, Pierre Auger (cosmic ray) Observatory neutrino telescopes AMANDA/IceCube are illustrated simplest but nevertheless representative example: production Schwarzschild holes their observation via Hawking...
After a short review of the ultrahigh energy cosmic ray puzzle - apparent observation rays originating from cosmological distances with energies above expected Greisen-Zatsepin-Kuzmin cutoff 4x10^{19} eV we consider strongly interacting neutrino scenarios as an especially interesting solution. We show that all features spectrum 10^{17} to 10^{21} can be described originate simple power-like injection protons, under assumption neutrino-nucleon cross-section is significantly enhanced at center...