17924332
HARDNESS RATIO ESTIMATION IN LOW COUNTING X-RAY PHOTOMETRY
Hardness ratios are commonly used in X-ray photometry to roughly indicate spectral properties. They are usually defined as the ratio of counts in two different wave bands. This definition, however, is problematic when the counts are very limited. Here we instead define the hardness ratio using the lambda-parameter of Poisson processes and develop an estimation method via Bayesian statistics. Our Monte Carlo simulations show the validity of our method. Based on this new definition we can estimate the hydrogen column density for the photoelectric absorption of X-ray spectra in the case of low counting statistics.
119316237
Fermionization, Triangularization and Integrability
In this article, we derive the fermionic formalism of Hamiltonians as well as corresponding excitation spectrums and states of Calogero-Sutherland(CS), Laughlin and Halperin systems, respectively. In addition, we study the triangular property of these Hamiltonians and prove the integrability in these three cases.
119164535
Hyperon Production from Neutrino–Nucleon Reaction
The neutrino induced hyperon production processes $${\bar{\nu}_{e/\mu} + p \to e^+/\mu^+ + \pi + \Lambda/\Sigma}$$ν¯e/μ+p→e+/μ++π+Λ/Σ may provide a unique clean place for studying low energy $${\pi\Lambda/\Sigma}$$πΛ/Σ interaction and hyperon resonances below KN threshold. The production rates for some neutrino induced hyperon production processes are estimated with theoretical models. Suggestions are made for the study of hyperon production from neutrino–nucleon reaction at present and future neutrino facilities.
118362258
Thermal non-Gaussianity in holographic cosmology
Recently it has been shown that the thermal holographic fluctuations can give rise to an almost scale invariant spectrum of metric perturbations since in this scenario the energy is proportional to the area of the boundary rather than the volume. Here we calculate the non-Gaussianity of the spectrum of cosmological fluctuations in holographic phase, which can imprint on the radiation dominated universe by an abrupt transition. We find that if the matter is phantom-like, the non-Gaussianity fNLequil can reach O(1) or even be larger than O(1). Especially in the limit ω→−5/3, the non-Gaussianity is very large and negative. Furthermore, since the energy is proportional to the area, the thermal holographic non-Gaussianity depends linearly on k if we neglect the variation in T during the transition (fixed temperature).
15138971
The first calculation for the mass of the ground 4(++) glueball state on lattice
Under the quenched approximation, we perform a lattice calculation for the mass of the ground 4(++) glueball state in E++ channel on a D = 3+1 lattice. Our calculation shows that the mass of this state is M-G(4(++)) = 3.65(6)(18) GeV, which rules out the 4(++) or mainly 4(++) glueball state interpretation for xi(2230).
39742923
Metal-insulator transition by holographic charge density waves.
We construct a gravity dual for charge density waves (CDWs) in which the translational symmetry along one spatial direction is spontaneously broken. Our linear perturbation calculation on the gravity side produces the frequency dependence of the optical conductivity, which exhibits the two familiar features of CDWs, namely, the pinned collective mode and gapped single-particle excitation. These two features indicate that our gravity dual also provides a new mechanism to implement the metal to insulator phase transition by CDWs, which is further confirmed by the fact that dc conductivity decreases with the decreased temperature below the critical temperature.
204926501
Covariant tensor formalism for partial wave analyses of psi decays into gamma B anti-B
Recently BES2 collaboration observed an enhancement near the $p\bar p$ invariant mass spectrum. Using the covariant tensor formalism, here we provide theoretical formulae for the partial wave analysis (PWA) of the $\psi$ radiative decay channels $\psi \to \gamma p\bar p, \gamma\Lambda\bar \Lambda, \gamma\Sigma \bar\Sigma, \gamma\Xi\bar \Xi$ . By performing the Monte Carlo simulation, we give the angular distributions for the photon and proton in the process of $J/\psi \to \gamma p\bar p$, which may serve as a useful reference for the future PWA on these channels.