arXiv subjects

Guey-Lin Lin

Publications and source records attributed to Guey-Lin Lin.

At least 55 records · Page 3Linked to original sources

arXiv2005

A semi-analytic calculation on the atmospheric tau neutrino flux in the GeV to TeV energy range

We present a semi-analytic calculation on the atmospheric tau neutrino flux in the GeV to TeV energy range. The atmospheric $ν_τ$ flux is calculated for the entire zenith angle range. This flux is contributed by the oscillations of muon neutrinos coming from the two-body $π, K$ decays and the three-body $μ^{\pm}$ decays, and the intrinsic tau neutrino flux surviving the oscillations. The uncertainties in our calculations are discussed in detail. The implications of our result are also discussed.

hep-ph↗

arXiv2005

On the Prospects of Tau Neutrino Astronomy in Gev Energies and Beyond

We point out the opportunity of tau neutrino astronomy for neutrino energies of the order of 10 GeV to 10$^{3}$ GeV. In this energy range, it is demonstrated that the flavor dependence in the background atmospheric neutrino flux leads to drastically different prospects between the observation of astrophysical muon neutrinos and that of astrophysical tau neutrinos. Taking the galactic-plane neutrino flux as a targeted astrophysical source, we found that the galactic-plane tau neutrino flux dominates over the atmospheric tau neutrino flux for neutrino energies beyond 10 GeV. Hence the galactic-plane can in principle be seen through tau neutrinos with energies greater than 10 GeV. In a sharp contrast, the galactic-plane muon neutrino flux is overwhelmed by its atmospheric background until the energy of $10^{6}$ GeV.

hep-ph↗

arXiv2005

The matter effects to neutrino oscillations ν_μ\to ν_e, ν_μat very long baselines and the neutrino mixing angles θ_13 and θ_23

We study the matter effects to neutrino oscillations ν_μ\to ν_e and ν_μ\to ν_μat very long baselines. It has been observed that, for a very long baseline L~10000 km, the resonance peak for the ν_μ\to ν_e oscillation and the local minimum of the ν_μsurvival probability occurs at similar energies. With a good knowledge on the absolute value of Δm_{31}^2, measurements of the above oscillation probabilities, P_{μe} and P_{μμ}, can be performed with the neutrino energy tuned to the resonance peak of the ν_μ\to ν_e oscillations. We show that the variations of CP violating phase and the solar neutrino mixing parameters have negligible effects on P_{μe} and P_{μμ} for such a long baseline. Hence P_{μe} and P_{μμ} together determine the mixing angles θ_{13} and θ_{23}. Around the resonance peak for ν_μ\to ν_e oscillations, the dependencies of P_{μe} and P_{μμ} on the above mixing angles are worked out in detail, and the implications of such dependencies are discussed.

hep-ph↗

arXiv2003

High energy tau neutrinos: production, propagation and prospects of observations

High energy tau neutrinos with energy greater than several thousands of GeV may be produced in some astrophysical sites. A summary of the intrinsic high energy tau neutrino flux estimates from some representative astrophysical sites is presented including the effects of neutrino flavor oscillations. The presently envisaged prospects of observations of the oscillated high energy tau neutrino flux are mentioned. In particular, a recently suggested possibility of future observations of Earth-skimming high energy tau neutrinos is briefly discussed.

hep-ph↗

arXiv2002

The technique of inverse Mellin transform for processes occurring in a background magnetic field

We develop the technique of inverse Mellin transform for processes occurring in a background magnetic field. We show by analyticity that the energy (momentum) derivatives of a field theory amplitude at the zero energy (momentum) is equal to the Mellin transform of the absorptive part of the amplitude. By inverting the transform, the absorptive part of the amplitude can be easily calculated. We apply this technique to calculate the photon polarization function in a background magnetic field.

hep-ph↗

arXiv2002

On non hadronic origin of high energy neutrinos

Some of the non hadronic interactions, such as the ηresonance formation in the γγinteractions and the muon pair production in the eγinteractions, are identified as possible source interactions for generating high energy neutrinos in the cosmos.

hep-ph↗

arXiv2002

Comparison of high-energy galactic and atmospheric tau neutrino flux

We compare the tau neutrino flux arising from the galaxy and the earth atmosphere for 10^3 < E/GeV < 10^11. The intrinsic and oscillated tau neutrino fluxes from both sources are calculated. The intrinsic galactic ν_τ flux (E > 10^3 GeV) is calculated by considering the interactions of high-energy cosmic-rays with the matter present in our galaxy, whereas the oscillated galactic ν_τ flux is coming from the oscillation of the galactic ν_μ flux. For the intrinsic atmospheric ν_τ flux, we extend the validity of a previous calculation from E < 10^6 GeV up to E < 10^11 GeV. The oscillated atmospheric ν_τ flux is, on the other hand, rather suppressed. We find that, for 10^3 < E/GeV < 5\cdot 10^7, 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 mention the presently envisaged prospects for observing these high-energy tau neutrinos.

hep-ph↗

arXiv2002

Strong-Field QED and the Inverse Mellin Transform

We introduce the technique of inverse Mellin transform in a problem of strong-field QED. We show that the {\it moments} of pair production width in a uniform background magnetic field are proportional to the derivatives of photon polarization function at the zero momentum. Hence, the pair-production width or the absorptive part of the photon polarization function is calculable from the latter by the inverse Mellin transform. Using the {\it Kramers-Kronig} relation, the dispersive part of photon polarization function can be computed as well. Therefore the analytic property of the photon polarization function in all energy range is obtained. We also discuss briefly the possible extensions of this technique to other problems.

hep-th↗

arXiv2001

Implications of $\barν_{e}e^{-}\to W^{-}γ$ for high-energy $\barν_e$ observation

Absorption of high-energy $\barν_e$ over electrons above the W boson production threshold is reexamined. It is pointed out that, in the case of photon emissions along the direction of incident high-energy $\barν_e$, the kinematically allowed average energy carried by the final state hard photon can be $\leq 1%$ of the incident $\barν_e$ energy above the W boson production threshold. The differential energy spectrum for the final state hard photon is calculated. We also discuss implications of our results for the prospective search of high-energy $\barν_e$ through this final state hard photon.

hep-ph↗

arXiv2001

Phenomenology of Higgs bosons in the Zee-Model

To generate small neutrino masses radiatively, the Zee-model introduces two Higgs doublets and one weak-singlet charged Higgs boson to its Higgs sector. From analyzing the renormalization group equations, we determine the possibile range of the lightest CP-even Higgs boson ($h$) mass and the Higgs boson self-couplings as a function of the cut-off scale beyond which either some of the coupling constants are strong enough to invalidate the perturbative analysis or the stability of the electroweak vacuum is no longer guaranteed. Using the results obtained from the above analysis, we find that the singlet charged Higgs boson can significantly modify the partial decay width of $h \to γγ$ via radiative corrections, and its collider phenomenology can also be drastically different from that of the charged Higgs bosons in the usual two-Higgs-doublet models.

hep-ph↗

arXiv2000

The Dispersive Approach to Electroweak Processes in the Background Magnetic Field

We propose a new method to compute amplitudes of electroweak processes in the strong background magnetic field, using $γ\to e^+e^-$ as an example. We show that the {\it moments} of $γ\to e^+e^-$ width are proportional to the derivatives of photon polarization function at the zero energy. Hence, the pair-production width can be easily calculated from the latter by the inverse Mellin transform. The prospects of our approach are commented.

hep-ph↗

arXiv2000

Another Look at Charged Higgs Boson Production at LEP

The current atmospheric and solar neutrino experimental data favors the bi-maximal mixing solution of the Zee-type neutrino mass matrix in which neutrino masses are generated radiatively. This model requires the existence of a weak singlet charged Higgs boson. While low energy data are unlikely to further constrain the parameters of this model, the direct search of charged Higgs production at the CERN LEP experiments can provide useful information on this mechanism of neutrino mass generation by analyzing their data with electrons and/or muons (in contrast to taus or charms) in the final state with missing transverse energies. We also discuss the difference in the production rates of a weak singlet from a weak doublet charged Higgs boson pairs at LEP.

hep-ph↗

arXiv2000

A new look at the pair-production width in a strong magnetic field

We reexamine the process $γ\to e^++ e^-$ in a background magnetic field comparable to $B_c\equiv m_e^2/e$. This process is known to be non-perturbative in the magnetic-field strength. However, it can be shown that the {\it moments} of the above pair production width is proportional to the derivatives of photon polarization function at the zero energy, which is perturbative in $B$. Hence, the pair-production width can be easily obtained from the latter by the inverse Mellin transform. The implications of our approach are discussed.

hep-ph↗

arXiv2000

The weak-field expansion for processes in a homogeneous background magnetic field

The weak-field expansion of the charged fermion propagator under a uniform magnetic field is studied. Starting from Schwinger's proper-time representation, we express the charged fermion propagator as an infinite series corresponding to different Landau levels. This infinite series is then reorganized according to the powers of the external field strength $B$. For illustration, we apply this expansion to $γ\to ν\barν$ and $ν\to νγ$ decays, which involve charged fermions in the internal loop. The leading and subleading magnetic-field effects to the above processes are computed.

hep-th↗

arXiv1999

The inclusive B->eta' X_s decay and b-> sg* form factors

We compute the branching ratio of inclusive $B \to η' X_s$ decay based upon the QCD anomaly mechanism: $b\to s+g^*\to s+g+η'$. To obtain a reliable $B \to η' X_s$ branching ratio, we calculate the $b\to s+g^*$ form factors up to the next-to-leading-logarithmic(NLL) approximation. We point out that the Standard Model prediction for $B\to η' X_s$ is consistent with the CLEO data, in contrast to the claims of some previous works.

hep-ph↗

arXiv1999

Neutrino-photon scattering and its crossed processes in a background magnetic field

We study the neutrino-photon processes such as $γγ\to ν\barν$ and $νγ\to νγ$ in a background magnetic field smaller than the critical magnetic field $B_c\equiv m_e^2/e$. Using Schwinger's proper-time method, we extract leading magnetic-field contributions to the above processes. Our result is valid throughout the kinematic regime where both neutrino and photon energies are significantly smaller than $m_W$. We briefly discuss the astrophysical implications of our result.

hep-ph↗

arXiv1999

Perturbative QCD study of the B-> K^* gamma decay

We apply the perturbative QCD factorization theorem developed recently for nonleptonic heavy meson decays to the radiative decay $B\to K^*γ$. In this formalism the evolution of the Wilson coefficients from the $W$ boson mass down to the characteristic scale of the decay process is governed by the effective weak Hamiltonian. The evolution from the characteristic scale to a lower hadronic scale is formulated by the Sudakov resummation. Besides computing the dominant contribution arising from the magnetic-penguin operator $O_7$, we also calculate the contributions of four-quark operators. By fitting our prediction for the branching ratio of the $B\to K^*γ$ decay to the CLEO data, we determine the $B$ meson wave function, that possesses a sharp peak at a low momentum fraction.

hep-ph↗

arXiv1999

B--> eta' X_s in the Standard Model

We study $B \to η' X_s$ within the framework of the Standard Model. Several mechanisms such as $b \to η' s g$ through the QCD anomaly, and $b \to η's $ and $B\to η' s \bar q$ arising from four-quark operators are treated simultaneously. Using QCD equations of motion, we relate the effective Hamiltonian for the first mechanism to that for the latter two. By incorporating next-to-leading-logarithmic(NLL) contributions, the first mechanism is shown to give a significant branching ratio for $B\to η' X_s$, while the other two mechanisms account for about 15% of the experimental value. The Standard Model prediction for $B\to η' X_s$ is consistent with the CLEO data.

hep-ph↗