【作者】 黄秀菊；

【导师】 王永久；

【作者基本信息】 湖南师范大学 ， 理论物理， 2006， 博士

【摘要】 中微子是基本粒子家族中重要且具有特色的成员之一,是唯一只参与弱相互作用的粒子,它在理论物理学及天体物理学中都占有着十分重要的地位。 泡利提出中微子假说之后,人们进行了一系列捕获中微子的实验。现在这些实验都用无可辩驳的事实证明了中微子是客观存在的基本粒子,同时也促使人们从多方面对中微子进行深入的研究。其中中微子的质量问题和中微子振荡现象是研究的热门课题。在费米弱作用理论乃至弱电统一理论中,都是把中微子当作无静止质量的粒子来处理的。用这样的理论来计算各种物理过程中的结果,都与实验符合得很好。另一方面,如果中微子质量不为零,则可很自然地解释某些现象(如宇宙中的热暗物质问题,太阳中微子丢失问题等)。于是一些理论也试图赋予中微子以质量,同时人们也在用不同的方法来测量和计算中微子的质量。虽然随着实验技术的飞速发展,实验测量到的中微子质量上限值不断下降,但目前各种实验还未精确确定中微子的质量值。 另外,早在1958年,Pontecorvo就指出,如果中微子质量不为零,则不同种类的中微子之间可能会相互转化,即产生中微子振荡现象。由中微子振荡的量子力学可知,在探测点发现一种中微子转化为另一种中微子的振荡几率与混合角、中微子束的平均能量、中微子产生源—探测器间的距离以及两种中微子的质量平方差有关。本文在此基础上主要讨论中微子振荡的干涉相因子以及中微子振荡中的CP破坏效应。因此,本文的结构安排如下: 在第一章的引言中,介绍了中微子的发现、中微子的质量、以及中微子的混合和振荡现象,然后在此基础上,用量子力学的语言描述了中微子的振荡。 在第二章中,介绍了平直时空中的中微子振荡,得到了中微子振荡的干涉相因子。并且指出此因子与中微子束的平均能量、两种中微子质量平方差以及中微子产生点到探测点间的距离有关。更多还原

【Abstract】 Neutrino is one of the important and characteristic particles in elementary particle family, and the one only participating in the weak interaction. It plays an important role in theoretical physics and astrophysics.After Pauli put forward the neutrino hypothesis, a series of experiments were done for catching for the neutrino. Now, these experiments have proved that the neutrino is the elementary particle that existing externally, which makes people do deeply research on it in many ways. And the mass of the neutrino and mass neutrino oscillations have become hot topics. In the Fermi weak interaction theory and even in the electro-weak unification theory, the neutrino is looked as the massless particle. On the basis of these theories, the results calculated in all kinds of physical process are in good agreement with the experiments. On the other hand, if the mass of the neutrino is nonzero, we can naturally explain some phenomenon such as the hot dark matter in cosmos, the missing of the solar neutrino, etc. So in some theoretical models the neutrino is trying to be endowed with the mass. At the same time, different methods are used to measure and calculate the mass of the neutrino. With the quick development of the experiment technique, the upper limit of the mass of the neutrino measured in experiments is declining perpetually, but at present any experiment doesn’t give a definite and exact value to the mass of the neutrino.On the other hand, in 1958, Pontecorvo pointed out that if the mass of neutrino is nonzero, the different kind of neutrinos will transform commuta-tively, that is mass neutrino oscillations happens. From the quantum mechanics of neutrino oscillations we known that at the detector point the oscillation probability of one kind of neutrino transforming into another is relative to the mixing angle, the average energy of the neutrino beam, the source-detector distance and the mass-squared difference between two kinds of neutrinos. In the basis of this, our paper mainly discussed the interference phase factor and the CP violation in mass neutrino oscillations. So we organize our paper as follows:In chapter I , we introduce the discovery , the mass, the mixing and the oscillation of the neutrino, in the basis of which, we present the quantum mechanics of neutrino oscillations.In chapter II , we discuss the neutrino oscillations in flat space-time, and present the interference phase factor. From the result we point out that the phase factor is relative to the average energy of the neutrino, mass-squared difference between two kinds of neutrinos and the source-detector distance.In chapter III, resorting to the geodesic, we discuss the mass neutrino oscillations in Einstein’s gravitational theory. With the standard method, we firstly discussed the interference phase factor of neutrino oscillation in Schwarz-schild space-time. Then with the same method we present the phase factor in Reissner-Nordstrom space-time and Kerr space-time, respectively. Prom the result, we known that, though the existence of the charge of the Reissner-Nordstrom field source and the angle momentum of the Kerr field source will have contribution to the phase factor, but comparing to the result in Schwarz-schild field, the contribution is very little. At last, we calculate the interference phase factor in Robertson-Walker space-time.In chapter IV and V, we calculate the interference phase factor of neutrino oscillation in static spherically symmetric space-time in Brans-Dicke (B-D)gravitational theory and torsion gravity, respectively. The contribution obtained in B-D gravitational theory to the quantum mechanical phase of neutrino are very significant and could be considered as a test for establishing the validity of B-D theory. Prom the result in torsion gravity we find that the modification to the vacuum phase factor of mass neutrino by torsion, although bigger than that by general relativity in some conditions, is very small. Therefore, the mass neutrino oscillation experiment cannot provide a criterion to adjudge which gravitational theory is preferred, general relativity, or other gravitational theories.In chapter VI, we introduce the violation of the symmetry under the united operation between the charged conjugate and the parity, or the CP violation. Then we present the theoretical study and the experimental detect ofthe direct CP violation, the new sources and mechanism of CP violation. In the basis of the above, we discuss the CP violation effect in neutrino oscillations, in which we point out that in the two flavor neutrino oscillations, since the mixing matrix is real, there is no CP violation, but in the three flavor neutrino oscillations, the mixing matrix is complex, so there exists CP violation.更多还原