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.     

Neutrinoless Double-Beta Decay to Excited 0+ States Mediated by Light Majorana Neutrinos

The neutrinoless double-beta decay (0 decay) to the first excited 0⁺ collective final state is examined for A = 76, 82, 100 and 136 nuclei by assuming light Majorana neutrino exchange mechanism. Realistic calculations of nuclear matrix elements are performed within the renormalized Quasiparticle Random Phase Approximation. Transitions to the first excited two-quadrupole phonon 0⁺ state are described within a boson expansion formalism. It is found that the ¹⁰⁰Mo is a good candidate for experimental study of the 0 decay to excited 0⁺ state due to small suppression of this transition relative to the transition to the ground state.     

无中微子双贝塔衰变：寻找马约拉纳中微子之路

无中微子双贝塔衰变是目前粒子物理与核物理学家积极寻找的一种极其稀有的原子核衰变模式。它的发现将验证中微子是否是其本身的反粒子,也就是通常指的马约拉纳费米子。同时这一物理过程破坏轻子数守恒,也可以为宇宙初期的正反物质不对称性提供重要的条件。鉴于其极重要的物理意义,国际上多个实验组利用不同的探测器技术,在多种不同的目标同位素中寻找这一突破粒子物理标准模型的稀有衰变。目前主流实验还未发现确定的无中微子双贝塔衰变信号,但对其半衰期的限制已经达到了10²⁶年量级。国内近期也开展了一系列预研实验,期望在未来几年内可以确定一到两个切实可行的实验方案,开展吨级实验。     

Search for supersymmetry at LHC

One of the main motivations for the experiments at the Large Hadron Collider (LHC), scheduled to start around 2006, is to search for supersymmetric particles. The region of the parameter space of the minimal supersymmetric standard model, where supersymmetry can be discovered, is investigated. We show that if supersymmetry exists at the electroweak scale, it would be easy to find signals for it at the LHC. If the LHC does find supersymmetry, this would be one of the greatest achievements in the history of theoretical physics.     

无中微子双β衰变相关的中微子势（英文）

介绍了在双β衰变中的闭合近似下的原子核矩阵元,并在此基础上研究了无中微子双β衰变的中微子势部分及统计性质。分析结果显示,费米型和伽莫夫-泰勒型矩阵元部分贡献了几乎相等的正值,并且费米型部分一般比伽莫夫-泰勒型部分的贡献稍大,而张量部分的贡献虽小但不可忽略,其中有少量矩阵元为负。阐明了无中微子双β衰变的中微子势中费米型、伽莫夫-泰勒型及张量部分大于零矩阵元的关联。该统计结果粗略地揭示了这些组份对原子核矩阵元的贡献。Nuclear matrix element in double beta decay under the closure approximation is outlined, in which neutrino potential for neutrinoless double beta decay is studied with focusing on its statistical property. It is shown from the analysis that Fermi and Gamow-Teller parts provide almost the same positive values with the Fermi part slightly larger than the Gamow-Teller part in general, while the tensor part includes small but non-negligible positive and negative values. Positive correlation of the values between Fermi, Gamow-Teller, and tensor parts has been clarified. The statistics provides a gross view of understanding amplitude of constitutional components of the nuclear matrix element.     

Search for heavy Majorana neutrinos at future lepton colliders

A nonzero neutrino mass may be a sign of new physics beyond the standard model (SM). To explain the small neutrino mass, we can extend the SM using right-handed Majorana neutrinos in a low-scale seesaw mechanism, and the CP violation effect can be induced due to the CP phase in the interference of heavy Majorana neutrinos. The existence of heavy Majorana neutrinos may lead to lepton number violation processes, which can be used to search for the signals of heavy Majorana neutrinos. In this paper, we focus on the CP violation effect related to two generations of heavy Majorana neutrinos at \begin{document}$ 15 $\end{document} GeV \begin{document}$ <m_{N_1}< 70 $\end{document} GeV in the pair production of W bosons and rare decays. It is valuable to investigate Majorana neutrino production signals and the related CP violation effects in rare W boson decays at future lepton colliders.     

介子束缚态相对论本征方程的非微扰重整化

介子结合态本征方程中δ相互作用可用T矩阵进行非微扰重整化,深入理解重整化的一些基本问题:物理结果与重正化点的选取无关,T矩阵非微扰重整化的物理实质. Nonperturbative T-matrix renormalization of the relativistic eigen equation for meson mass spectra is described and the expressions for eigen mass spectra and eigen wave functions are given.     

Vacuum Polarization Bubble Effects on the Triangle Relations for B Meson Charmless Decay Amplitudes

Assuming that factorization is valid and that contributions of the exchange, annihilation, and penguin-annihilation diagrams are negligible, we study the effects of the QCD vacuum polarization bubbles on the decay amplitudes of some B meson charmless decays into two light pseudoscalars. The bubbles have much less effects on B⁰→π⁺π^-, π^-K⁺, π⁰K⁰ than on B⁰→π⁰π⁰ thus the triangle relation √2A(B⁺→π⁺π⁰) = A(B⁰→π^-K⁺)/R_u+√2A(B⁰→π⁰K⁰)/R_u is changed slightly while √2A(B⁺→π⁺π⁰)=√2A(B⁰→π⁰π⁰)+A(B⁰→π⁺π^-) is altered significantly. This may indicate that in order to test or use these triangle relations other higher order QCD corrections should also be carefully taken into consideration.     

菲尔德–费曼模型中的介子碎裂函数

从菲尔德–费曼的叠代模型出发,考虑到入射夸克的味结构,研究了π介子的碎裂函数Duπ+,Ddπ+,和Dsπ+,并将分析结果和实验数据进行了比较,对K介子的碎裂函数DsK+(z),DuK+(z),DsK+(z)和DdK+(z)作出的预言将被进一步的实验检验。     

D介子稀有衰变研究

利用工作在北京正负电子对撞机(BEPC)上的北京谱仪(BES)收集到的33pb^－1的Ψ(3770)数据,寻找D介子味道改变中性流(FCNC)和轻子数不守恒(LNV)的稀有衰变, 包括4个D⁰介子的衰变模式(K⁰e⁺e^－,Φe⁺e^－,ρ⁰e⁺e^－和K^*0e⁺e^－)和6个D⁺介子的衰变模式(K^－e⁺e⁺,K⁺e⁺e^－,π^－e⁺e⁺, π⁺e⁺e^－,K^*－e⁺e⁺和K^*+e⁺e^－). 没有发现信号,给出90%置信水平的上限. 其中, D⁺介子的两个衰变模式D⁺→K^*－e⁺e⁺和D⁺→K^*+e⁺e^－的上限是首次测量.     

Two-loop Majorana neutrino mass and magnetic moment in a gauge model

Two-loop contributions to Majorana mass and transition magnetic moment in a gauge model not in conflict with decaying neutrino dark matter (DDM) hypothesis have been studied. Another variant of an earlier model [J Dhar and S Dev,Pramana — J. Phys. 39 541 (1992)] consistent with the DDM hypothesis is proposed and is shown to lead to large enough neutrino magnetic moment and consistent with the phenomenological constraints on neutrino mass.     

Matter Effects on Neutrino Oscillations in Different Supernova Models

In recent years,with the development of simulations about supernova explosion,we have a better understanding about the density profiles and the shock waves in supernovae than before.There might be a reverse shock wave,another sudden change of density except the forward shock wave,or even no shock wave,emerging in the supernova.Instead of using the expression of the crossing probability at the high resonance,PH,we have studied the matter effects on neutrino oscillations in different supernova models.In detail,we have calculated the survival probability of νe(P_s)and the conversion probability of ν_x(P_c) in the Schrodinger equation within a simplified two-flavor framework for a certain case,in which the neutrino transfers through the supernova matter from an initial flavor eigenstate located at the core of the supernova.Our calculations was based on the data of density in three different supernova models obtained from simulations.In our work,we do not steepen the density gradient around the border of the shock wave,which differs to what was done in most of the other simulations.It is found that the mass and the density distribution of the supernova do make a difference on the behavior of P_s and P_c.With the results of P_s and P_c,we can estimate the number of νe(and ν_x) remained in the beam after they go through the matter in the supernova.     

Rare Decay B → Xsvv in the Two-Higgs-Doublet Model of Type-Ⅲ

In this paper, we calculated the new physics contribution to theoretically very clean rare decay B → Xsvvin the general two-Higgs-doublet model (model Ⅲ). Within the considered parameter space, we found that (a) thenew physics contribution can provide one to two orders of enhancement to the branching ratio B(B → Xsvv) and cansaturate the experimental bound on B(B → Xs vv) in some regions of the parameter space; (b) besides the CLEO data ofB → Xsγ, the ALEPH upper limit on B(B → Xsvv) also leads to further constraint on the size of the Yukawa couplingλtt: λtt ＜ 6.4 for λbb = 2.7 and mH+ = 200 GeV.     

Effective potential for emergent Majorana fermions in superconductor systems

Majorana fermions cannot be found in nature as a free fundamental particle. Nevertheless, in condensed matter systems, they can emerge as a collective excitation. In this work, using functional integration techniques, we calculated the effective potential for emergent Majorana fermions in the Kitaev chain. In this case, we have shown the behavior of the superconductor parameter as a function of temperature. Furthermore, we considered surface-induced superconductivity in a Topological Insulator and calculated the effective potential for emergent Majorana fermions in this system. In the case of an s-wave superconductor, we obtained a gap equation equivalent to that one appearing in a quasi-two-dimensional Dirac electronic system, a candidate to explain high-Tc superconductivity. Finally, for the p-wave superconductor, we have obtained a critical value of the electron-electron interaction in the surface of the Topological Insulator, determining the existence or not of induced superconductivity, a remarkable result to guide experiments.     

Direct Search for keV-Sterile Neutrino in Nuclear Decay. Troitsk Nu-Mass (Scientific Summary)

JETP Letters - We present a brief review of experimental status in searching for hypothetical sterile neutrino in nuclear decay in laboratory testing. The main idea is based on search for an...     

热密π介子环境中的ρ介子谱函数

利用描述ρ-π耦合的有效模型, 研究了热密π介子环境中的ρ介子谱函数. 数值计算的结果表明, 随着温度和π介子化学势的升高, 谱函数变宽, 且峰的位置向高不变质量区移动.     

A theorem for the existence of Majorana fermion modes in spin-orbit-coupled semiconductors

We prove an index theorem for the existence of Majorana zero modes in a semiconducting thin film with a sizable spin-orbit coupling when it is adjacent to an s-wave superconductor. The theorem, which is analogous to the Jackiw-Rebbi index theorem for the zero modes in mass domain walls in one-dimensional Dirac theory, applies to vortices with odd flux-quantum in a semiconducting film in which s-wave superconductivity and a Zeeman splitting are induced by proximity effect. The momentum space construction of the zero-mode solution presented here is complementary to the approximate real space solution of the Bogoliubov-de Gennes equations at a vortex core (Sau et al., arXiv:0907.2239 [17]), proving the existence of non-degenerate zero-energy Majorana excitations and the resultant non-Abelian topological order in the semiconductor heterostructure. With increasing magnitude of the proximity-induced pairing potential, the non-Abelian superconducting state makes a topological quantum phase transition to an ordinary s-wave superconducting state which no topological order.     

微扰QCD方法计算稀有衰变B+→D+s(-K)*0

在标准模型中,稀有衰变道B+→D+s(-K)*0只有通过纯湮没图才可以发生.这样这个衰变道的分支比很小.利用基于kT因子化的微扰方法给出分支比的预测,发现它在10-8的量级上.这个衰变道估计在将来的LHC上得到测量,对检验标准模型以及探寻新物理有着重要的意义.