Direct Detection of Dark Matter with Resonant Annihilation

In the scenario where the dark matter (DM) particles χχ pair annihilate through a resonance particle R, the constraint from DM relic density makes the corresponding cross section for DM-nuclei elastic scattering extremely small, and can be below the neutrino background induced by the coherent neutrino-nuclei scattering, which makes the DM particle beyond the reach of the conventional DM direct detection experiments. We present an improved analytical calculation of the DM relic density in the case of resonant DM annihilation for s- and p-wave cases and invesitgate the condition for the DM-nuclei scattering cross section to be above the neutrino background. We show that in Higgs-portal type models, for DM particles with s-wave annihilation, the spin-independent DM-nucleus scattering cross section is proportional to Γ_R/m_R, the ratio of the decay width and the mass of R. For a typical DM particle mass ～50 GeV, the condition leads to Γ_R/m_R ≥O(10^-4). In p-wave annihilation case, the spin-independent scattering cross section is insensitive to Γ_R/m_R, and is always above the neutrino background, as long as the DM particle is lighter than the top quark. The real singlet DM model is discussed as a concrete example.     

Kasner 时空中的中微子振荡相位

研究了质量中微子在 Kasner 时空特殊情况下的传播相位和振荡特征长度,得到了中微子的零短程线相位是短程线相位一半的关系.当参数a=0时,Kasner 时空中的传播相位和史瓦希时空中的相同.这一问题的研究在宇宙学中是有意义的^[1-3]. 关键词： 传播相位 Kasner 时空 质量中微子 振荡特征长度     

Can a non-unitary effect be prominent in neutrino oscillation measurements?

Subject to neutrino experiments, the mixing matrix of ordinary neutrinos can still have small vi-olation from unitarity. We introduce a quasi-unitary matrix to interpret this violation and propose a natural scheme to parameterize it. A quasi-unitary factor △QF is defined to be measured in neutrino oscillation exper-iments and the numerical results show that the improvement in experimental precision may help us figure out the secret of neutrino mixing.     

Interference phase of mass neutrino in Reissner-NordstrSm-de Sitter space-time

The chemical potential of electrons in a strong magnetic field is investigated. It is shown that the magnetic field has only a slight effect on electron chemical potential when B < 1011 T, but electron chemical potential will decrease greatly when B > 1011 T. The effects of a strong magnetic field on electron capture rates for 60Fe are discussed, and the result shows that the electron capture sharply decreases because of the strong magnetic field.     

Entropic Uncertainty in Neutrino and Meson Systems

The dynamics of quantum‐memory‐assisted entropic uncertainty for the closed neutrino system in the context of two flavor oscillations and the meson system within the framework of open quantum system are investigated. It is found that the entropic uncertainty exists in close relation with the quantum correlation, and growing quantum correlation can decrease the uncertainty. The oscillatory behaviors of entropic uncertainty in neutrino system brought about by neutrino oscillating property are different from the decaying behaviors of entropic uncertainty in meson system induced by the meson decaying nature. In addition, the entropic uncertainty is always equal to its lower bound in the two subatomic systems. This study would throw light on the particle behavior characteristics of high energy physics, and may be useful to the tasks of quantum information‐processing implemented with subatomic system since the uncertainty principle plays vital role in quantum information science and technology.     

Exploring neutrino mass and mass hierarchy in the scenario of vacuum energy interacting with cold dark matter

We investigate the constraints on total neutrino mass in the scenario of vacuum energy interacting with cold dark matter. We focus on two typical interaction forms, i.e., Q=βHρ_c and Q=βHρ_∧. To avoid the occurrence of large-scale instability in interacting dark energy cosmology, we adopt the parameterized post-Friedmann approach to calculate the perturbation evolution of dark energy. We employ observational data, including the Planck cosmic microwave background temperature and polarization data, baryon acoustic oscillation data, a JLA sample of type Ia supernovae observation, direct measurement of the Hubble constant, and redshift space distortion data. We find that, compared with those in the ∧CDM model, much looser constraints on ∑m_ν are obtained in the Q=βHρ_c model, whereas slightly tighter constraints are obtained in the Q=βHρ_∧ model. Consideration of the possible mass hierarchies of neutrinos reveals that the smallest upper limit of ∑m_ν appears in the degenerate hierarchy case. By comparing the values of χ_min², we find that the normal hierarchy case is favored over the inverted one. In particular, we find that the difference △χ_min² ≡ χ_{IH; min}²-χ_{NH; min}² > 2 in the Q=βHρ_c model. In addition, we find that β=0 is consistent with the current observations in the Q=βHρ_c model, and β < 0 is favored at more than the 1σ level in the Q=βHρ_∧ model.     

Interference phase of mass neutrino in CM space--time

In the gravitational field of central mass with electric and magnetic charges and magnetic moment (CM space-time), this paper calculates the interference phase of mass neutrino along geodesic in the radial direction, and discusses the contribution of the electric and magnetic charges and magnetic moment of the central mass to the phase.     

Neutrino Mass Generation in SO(4) Model

Generation of neutrino mass in SO(4) model is proposed here. Thealgebraic structure of SO(4) is same as to that of SU(2)_L ×SU(2)_R. It is shown that the spontaneous symmetry breaking results three massive as well as three massless gauge bosons. The standard model theory according to which there exist three massive gauge bosons and a massless one is emergedfrom this model. In the framework of SU(2)_L × SU(2)_R a small Dirac neutrino mass is derived. It is also shown that such mass term may vanish with a special choice. The Majorana mass term is not considered here and thus in this model the neutrino mass does not follow seesaw structure.     

Gibbons-Maeda黑洞附近中微子场的熵

从Gibbons-Maeda(G-M)时空背景下的线元出发,利用WKB近似,由自旋为1/2的中微子场方程求得径向波数pkr,在此基础上利用brick-wall方法计算了G-M黑洞附近中微子场的自由能和熵,并与标量场的熵作了比较,发现中微子场的主项熵是标量场的主项熵的7/8倍.     

First measurements with the neutron decay spectrometer a SPECT

The neutron decay spectrometera SPECT has been built to perform a precise measurement of the proton spectrum shape in the decay of free neutrons. Such a measurement allows a determination of the neutrino electron angular-correlation coefficienta . The present best experiments have an uncertainty of Δa/a = 5% and since the seventies there is no substantial improvement. Witha SPECT, we aim for an uncertainty which is lower by more than an order of magnitude, thus enabling us to perform several precise tests of the Standard Model. In our first beam time at the particle physics beam MEPHISTO at the Forschungsneutronenquelle Heinz Maier-Leibnitz, we studied the properties of the spectrometer. The most serious problem turned out to be the situation- and time-dependent behavior of the background. From the data sets from this beam time in which a background problem was not obvious, we could extract a value ofa = - 0.1151±0.0040^stat , but we could not quantify the background uncertainty. We show ways to deal with the background and other problems for future beam times.