Weak Decays of Doubly Heavy Baryons: the 1/2→1/21/2\to 1/2 case

Very recently, the LHCb collaboration has observed in the final state $\Lambda_c^+ K^-\pi^+\pi^+$ a resonant structure that is identified as the doubly-charmed baryon $\Xi_{cc}^{++}$. Inspired by this observation, we investigate the weak decays of doubly heavy baryons $\Xi_{cc}^{++}$, $\Xi_{cc}^{+}$, $\Omega_{cc}^{+}$, $\Xi_{bc}^{(\prime)+}$, $\Xi_{bc}^{(\prime)0}$, $\Omega_{bc}^{(\prime)0}$, $\Xi_{bb}^{0}$, $\Xi_{bb}^{-}$ and $\Omega_{bb}^{-}$ and focus on the decays into spin $1/2$ baryons in this paper. At the quark level these decay processes are induced by the $c\to d/s$ or $b\to u/c$ transitions, and the two spectator quarks can be viewed as a scalar or axial vector diquark. We first derive the hadronic form factors for these transitions in the light-front approach and then apply them to predict the partial widths for the semi-leptonic and non-leptonic decays of doubly heavy baryons. We find that a number of decay channels are sizable and can be examined in future measurements at experimental facilities like LHC, Belle II and CEPC.Comment: 40 pages, 4 figures, to appear in EPJ

Electron-cyclotron maser and solar microwave millisecond spike emission

An intense solar microwave millisecond spike emission (SMMSE) event was observed on May 16, 1981 by Zhao and Jin at Beijing Observatory. The peak flux density of the spikes is high to 5 x 100,000 s.f.u. and the corresponding brightness temperature (BT) reaches approx. 10 to the 15th K. In order to explain the observed properties of SMMSE, it is proposed that a beam of electrons with energy of tens KeV injected from the acceleration region downwards into an emerging magnetic arch forms so-called hollow beam distribution and causes electron-cyclotron maser (ECM) instability. The growth rate of second harmonic X-mode is calculated and its change with time is deduced. It is shown that the saturation time of ECM is t sub s approx. equals 0.42 ms and only at last short stage (delta t less than 0.2 t sub s) the growth rate decreases to zero rather rapidly. So a SMMSE with very high BT will be produced if the ratio of number density of nonthermal electrons to that of background electrons, n sub s/n sub e, is larger than 4 x .00001

Inverse Problem Approach for Non-Perturbative QCD: Foundation

We propose a novel theoretical framework to calculate the non-perturbative QCD quantities. It starts from the dispersion relation of quantum field theory, separating the high-energy and low-energy scales and using the known perturbative theories to solve the unknown non-perturbative quantities by the inverse problem. We prove that the inverse problem of dispersion relation is ill-posed, with unique but unstable solutions. The regularization methods must be used to get the stable approximate solutions. The method is based on the strict mathematics, without any artificial assumptions. We have test some toy models to vividly show the main features of the inverse problem. It can be found that this approach can systematically improve the precision of the solutions.Comment: 23 pages, 8 figure

The loonguard research institute and the 2017 conference for food and medicine governance

Abstract. Poblematic food safety issues are emerging in contemporary societies, especially those undergoing economically and socially rapid developments. In such context, failures in market and governance mechanisms present challenging situations for serving quality and trust-worthy foods and medicine to people. Meanwhile, scientific progresses are slowed down due to unavailability of critical information regarding good practices for food and medicine governance.Keywords. Food, Medicine, Governance.JEL. H12, E62, H50, H69