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G. -L. Lin

Publications and source records attributed to G. -L. Lin.

9 recordsLinked to original sources
arXiv2011

Determinations of flavor ratios and flavor transitions of astrophysical neutrinos

We argue that an effective flavor discrimination in neutrino telescopes is the key to probe the flavor ratios of astrophysical neutrinos at the source and flavor transition mechanisms of these neutrinos during their propagations from the source to the Earth. We first discuss how well one can reconstruct the flavor ratios of astrophysical neutrinos at the source. We then discuss how to probe flavor transition mechanisms of propagating astrophysical neutrinos. In this regard, we propose a model independent parametrization for neutrino flavor transitions, with the neutrino oscillation as a special case.

hep-ph↗
arXiv2005

Tau Neutrino Astronomy in GeV Energies

We point out the opportunity of the tau neutrino astronomy for the neutrino energy E ranging between 10 GeV and 10^3 GeV. In this energy range, the intrinsic tau neutrino production is suppressed relative to the intrinsic muon neutrino production. Any sizable tau neutrino flux may thus arise because of the ν_μ\to ν_τ neutrino oscillations only. It is demonstrated that, in the presence of the neutrino oscillations, consideration of the neutrino flavor dependence in the background atmospheric neutrino flux leads to the drastically different prospects between the observation of the astrophysical muon neutrinos and that of the astrophysical tau neutrinos. Taking the galactic-plane neutrino flux as the targeted astrophysical source, we have found that the galactic-plane tau neutrino flux dominates over the atmospheric tau neutrino flux for E > 10 GeV. Hence, the galactic-plane can at least in principle be seen through the tau neutrinos with energies just greater than 10 GeV. In a sharp contrast, the galactic-plane muon neutrino flux is overwhelmed by its atmospheric background until E > 10^6 GeV.

hep-ph↗
arXiv2003

The high-energy galactic tau neutrino flux and its atmospheric background

We compare the tau neutrino flux arising from the galaxy and the earth atmosphere for $10^{3} \leq E/{GeV} \leq 10^{11}$. The intrinsic and oscillated tau neutrino fluxes from both sources are considered. We find that, for $E\geq 10^3$ GeV, the oscillated $ν_τ$ flux along the galactic plane dominates over the maximal intrinsic atmospheric $ν_τ$ flux, i.e., the flux along the horizontal direction. We also briefly comment on the prospects for observing these high-energy tau neutrinos.

astro-ph↗
arXiv2003

The energy spectrum of tau leptons induced by the high energy Earth-skimming neutrinos

We present a semi-analytic calculation of the tau-lepton flux emerging from the Earth, induced by the incident high energy neutrinos interacting inside the Earth for $10^{5} \leq E_ν/{\rm GeV} \leq 10^{10}$. We obtain results for the energy dependence of the tau-lepton flux coming from the Earth-skimming neutrinos, because of the neutrino-nucleon charged-current scattering as well as the resonant $\barν_e e^-$ scattering. We illustrate our results for several anticipated high energy astrophysical neutrino sources such as the AGNs, the GRBs, and the GZK neutrino fluxes. The tau lepton fluxes resulting from rock-skimming and ocean-skimming neutrinos are compared. Such comparisons can render useful information for the spectral indices of incident neutrino fluxes.

astro-ph↗
arXiv2002

On Analytic Properties of the Photon Polarization Function in a Background Magnetic Field

We examine the analytic properties of the photon polarization function in a background magnetic field, using the technique of inverse Mellin transform. The photon polarization function is first expressed as a power series of the photon energy $ω$ with $ω< 2m_e$. Based upon this energy expansion and the branch cut of the photon polarization function in the complex $ω$ plane, we compute the absorptive part of the polarization function with the inverse Mellin transform. Our results are valid for arbitrary photon energies and magnetic-field strengths. The applications of our approach are briefly discussed.

hep-ph↗
arXiv2001

Muon Pair Production by Electron-Photon Scatterings

The cross section for muon pair productions by electrons scattering over photons, $σ_{MPP}$, is calculated analytically in the leading order. It is pointed out that for the center-of-mass energy range, $s \geq 5 m^{2}_μ$, the cross section for $σ_{MPP}$ is less than $1 μ$b. The differential energy spectrum for either of the resulting muons is given for the purpose of high-energy neutrino astronomy. An implication of our result for a recent suggestion concerning the high-energy cosmic neutrino generation through this muon pair is discussed.

hep-ph↗
arXiv1997

Flavor Changing Neutral Higgs Couplings and Top-Charm Production at Next Linear Collider

We explore the possibility of detecting flavor changing neutral Higgs couplings at the Next Linear Collider (NLC) through $e^+e^-\to ν_e\bar{ν_e} t\bar{c}$. In the framework of a general two-Higgs doublet model, we perform a complete calculation and find that $σ(e^+e^-\to ν_eν_e t\bar{c}, ν_e\bar{ν_e} {\bar t}c)$ could reach $\sim 9$ fb for $\sqrt{s}=2 TeV$. This amounts to an annual production of 500 $t\bar{c}$ plus $\bar{t}c$ pairs at the NLC with an integrated luminosity of 50 fb$^{-1}$. The dependence of $tc$-production rate on the neutral scalar mixing angle is mild except when $\sin^2α\to 0 or 1$. The $ννW^+W^-$ background should be manageable after $b$-tagging, while $ννt\bar t$ background should not be a problem when the signal event rate is still interesting. The process, together with $e^+e^-\to ν_e\bar{ν_e} W^+W^-, ν_e\bar{ν_e} ZZ$ studies, offer the chance of measuring the $t$-$c$-Higgs coupling.

hep-ph↗
arXiv1993

Heavy Top Quark Effects in Vertices with Light External Fermions

We extend our previous work on non-linear realization of the top quark field, which is a consequence of its being much heavier than any other scales. One loop effective Lagrangian to account for virtual top effects is constructed in this article, for processes where there are two external fermions, as well as any number of bosons. Particularly, we focus on those terms which have power dependence on the top mass $m_t$.

hep-ph↗