分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-11-10
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2017-09-17
摘要: The three active light neutrinos are used to explain the neutrino oscillations.The inherently bi-large mixing neutrino mass matrix and the Fritzsch type,bi-small mixing charged lepton mass matrix are assumed. By requiring the maximal #23;μ −#23;#28; mixing for the atmospheric neutrino problem and the mass-squared difference approperiate for the almost maximal mixing solution to the solar neutrino problem, the following quantities are predicted: the #23;e−#23;μ mixing, Ve3, CP violation in neutrino oscillations, and the effective electron-neutrino mass relevant to neutrinoless double beta decays.
分类: 物理学 >> 核物理学 提交时间: 2016-09-12
摘要: We report an improved measurement of D0-D0bar mixing and a search for CP violation in D0 decays to CP-even final states K+K- and pi+pi-. The measurement is based on the final Belle data sample of 976/fb. The results are y_CP=(1.11 +- 0.22 +- 0.09)% and A_Gamma=(-0.03 +- 0.20 +- 0.07)%, where the first uncertainty is statistical and the second is systematic.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: We calculate the tree and penguin amplitudes in the B0→π+π− decay channel employing the perturbative QCD factorization approach. Using the amplitudes as input with the theoretical uncertainties sufficiently considered, we constrain the UT angle γ to 53∘≤γ≤70∘, from the measurements of the CP violation parameters Cπ+π− and Sπ+π− in B0→π+π−. The U-spin breaking effect between B0→π+π− and B0s→K+K− is estimated to be around 30\%.
分类: 物理学 >> 核物理学 提交时间: 2016-09-10
摘要: We report a measurement of the time-dependent CP asymmetry of B0->D(*)CP h0 decays, where the light neutral hadron h0 is a pi0, eta or omega meson, and the neutral D meson is reconstructed in the CP eigenstates K+ K-, K0S pi0 or K0S omega. The measurement is performed combining the final data samples collected at the Y(4S) resonance by the BaBar and Belle experiments at the asymmetric-energy B factories PEP-II at SLAC and KEKB at KEK, respectively. The data samples contain ( 471 +/- 3 ) x 10^6 BB pairs recorded by the BaBar detector and ( 772 +/- 11 ) x 10^6, BB pairs recorded by the Belle detector. We measure the CP asymmetry parameters -eta_f S = +0.66 +/- 0.10 (stat.) +/- 0.06 (syst.) and C = -0.02 +/- 0.07 (stat.) +/- 0.03 (syst.). These results correspond to the first observation of CP violation in B0->D(*)CP h0 decays. The hypothesis of no mixing-induced CP violation is excluded in these decays at the level of 5.4 standard deviations.
分类: 物理学 >> 基本粒子与场物理学 分类: 物理学 >> 交叉学科物理及相关领域的科学与技术 提交时间: 2016-06-15
摘要: Developing a theory that can describe everything in the universe is of great interest, and is closely relevant to M-theory, neutrino oscillation and charge-parity (CP) violation. Although M-theory is claimed as a grand unified theory, it has not been tested by any direct experiment. Here we show that existing neutrino oscillation experimental data supports one kind of high dimensional unified theory, such as M-theory. We propose a generalization of the tri-bimaximal neutrino mixing ansatz, and we find that the latest neutrino oscillation experimental data constraints dimension in a range between 10.46 and 12.93 containing 11, which is an important prediction of M-theory. This ansatz naturally incorporates the fractal feature of the universe and leptonic CP violation into the resultant scenario of fractal nearly tri-bimaximal flavor mixing. We also analyze the consequences of this new ansatze on the latest experimental data of neutrino oscillations, and this theory matches the experimental data. Furthermore, an approach to construct lepton mass matrices in fractal universe under permutation symmetry is discussed. The proposed theory opens an unexpected window on the physics beyond the Standard Model.
分类: 物理学 >> 核物理学 提交时间: 2016-09-13
摘要: The Majorana nature of massive neutrinos will be crucially probed in the next-generation experiments of the neutrinoless double-beta (0ν2β) decay. The effective mass term of this process, ⟨m⟩ee, may be contaminated by new physics. So how to interpret a discovery or null result of the 0ν2β decay in the foreseeable future is highly nontrivial. In this paper we introduce a novel three-dimensional description of |⟨m⟩ee|, which allows us to see its sensitivity to the lightest neutrino mass and two Majorana phases in a transparent way. We take a look at to what extent the free parameters of |⟨m⟩ee| can be well constrained provided a signal of the 0ν2β decay is observed someday. To fully explore lepton number violation, all the six effective Majorana mass terms ⟨m⟩αβ (for α,β=e,μ,τ) are calculated and their lower bounds are illustrated with the two-dimensional contour figures. The effect of possible new physics on the 0ν2β decay is also discussed in a model-independent way. We find that the result of |⟨m⟩ee| in the normal (or inverted) neutrino mass ordering case modified by the new physics effect may somewhat mimic that in the inverted (or normal) mass ordering case in the standard three-flavor scheme. Hence a proper interpretation of a discovery or null result of the 0ν2β decay may demand extra information from some other measurements.
分类: 物理学 >> 核物理学 提交时间: 2016-08-31
摘要: Given an accelerator-based neutrino experiment with the beam energy E \lesssim 1 GeV, we expand the probabilities of \nu_\mu \to \nu_e and \overline {\nu}_\mu \to \overline {\nu}_e oscillations in matter in terms of two small quantities \Delta_{21}/\Delta_{31} and A/\Delta_{31}, where \Delta_{21} \equiv m^2_2 - m^2_1 and \Delta_{31} \equiv m^2_3 - m^2_1 are the neutrino mass-squared differences, and A measures the strength of terrestrial matter effects. Our analytical approximations are numerically more accurate than those made by Freund in this energy region, and thus they are particularly applicable for the study of leptonic CP violation in the low-energy MOMENT, ESS\nuSM and T2K oscillation experiments. As a by-product, the new analytical approximations help us to easily understand why the matter-corrected Jarlskog parameter \widetilde{\cal J} peaks at the resonance energy E_* \simeq 0.14 GeV (or 0.12 GeV) for the normal (or inverted) neutrino mass hierarchy, and how the three Dirac unitarity triangles are deformed due to the terrestrial matter contamination. We also affirm that a medium-baseline neutrino oscillation experiment with the beam energy E lying in the E_* \lesssim E \lesssim 2 E_* range is capable of exploring leptonic CP violation with little matter-induced suppression.
分类: 物理学 >> 核物理学 提交时间: 2016-09-14
摘要: Given the best-fit results of six neutrino oscillation parameters, we plot the Dirac and Majorana unitarity triangles (UTs) of the 3\times 3 lepton flavor mixing matrix to show their real shapes for the first time. The connections of the Majorana UTs with neutrino-antineutrino oscillations and neutrino decays are explored, and the possibilities of right or isosceles UTs are discussed. In the neutrino mass limit of m_1 \to 0 or m_3 \to 0, which is allowed by current experimental data, we show how the six triangles formed by the effective Majorana neutrino masses \langle m\rangle_{\alpha\beta} (for \alpha, \beta = e, \mu, \tau) and their corresponding component vectors look like in the complex plane. The relations of such triangles to the Majorana phases and to the lepton-number-violating decays H^{++} \to \alpha^+ \beta^+ in the type-II seesaw mechanism are also illustrated.
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: We examine the prospects of making a joint analysis of neutrino oscillation at two baselines with neutrino superbeams. Assuming narrow band superbeams and a 100 kt water Cerenkov calorimeter, we calculate the event rates and sensitivities to the matter ef
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-06-18
摘要: With the assistance of a complex singlet, and an effective operator involving CP violations, the dark matter relic abundance and baryon asymmetry of the universe have been addressed simultaneously. We studied the electroweak baryogenesis mechanism systematically. The electroweak phase transition analysis indicates that the strong first order phase transition takes place by one-step or two-step type due to the dynamics of the energy gap between the electroweak vacuum and the vacuum of the complex singlet. The relation between the magnitude of baryon asymmetry of the universe and the phase transition type and strength has been explored in the framework of electroweak baryogenesis.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-15
摘要: We examined Zb (b) over bar and Zl (l) over bar couplings in the minimal supersymmetric model with explicit trilinear R-parity violating interactions. We found that the top quark couplings lambda (i3k)' and lambda (3j3)" can give sizable contributions through top quark loops. When deriving the bounds from R-b and R-l data, we also take into account the loop contributions of R-parity conserving interactions. The bounds from R-l are found to be stronger than those from R-b and serve as the hitherto strongest bounds for some couplings.
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-15
摘要: We examined Zb (b) over bar and Zl (l) over bar couplings in the minimal supersymmetric model with explicit trilinear R-parity violating interactions. We found that the top quark couplings lambda (i3k)' and lambda (3j3)" can give sizable contributions through top quark loops. When deriving the bounds from R-b and R-l data, we also take into account the loop contributions of R-parity conserving interactions. The bounds from R-l are found to be stronger than those from R-b and serve as the hitherto strongest bounds for some couplings.
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: The dimension-six CP-violating SU_L(2)\times U_Y(1) invariant operators involving the tau lepton are studied. The constraints from the available experimental data on tau dipole moments are derived. Under the current constraints, the induced CP-violating e
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: We discuss the prospects of a very long baseline neutrino oscillation experiment from HIPA to Beijing. The current understanding of neutrino oscillations, both theoretically and experimentally, are summarized. The figure of merits for interested physics m
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: This talk is a brief review of the recent studies on probing new physics through single top quark processes and probing exotic top quark decays at the upgraded Tevatron.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2016-12-28
摘要: In the next-to-minimal supersymmetric model (NMSSM) a light CP-odd Higgs boson is so far allowed by current experiments, which, together with a large tanβtan?β\tan\beta, may greatly enhance the rare dileptonic decays B\to X_s l^+ l^- and B_s\to l^+ l^- \g
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and scrutinize the property of the Higgs bosons in the allowed parameter space. These constraints come from the precision electroweak data, the direct search
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: We examine various direct and indirect constraints on the lepton-specific two-Higgs doublet model and scrutinize the property of the Higgs bosons in the allowed parameter space. These constraints come from the precision electroweak data, the direct search
分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-05-16
摘要: This talk is a review of the recent studies on probing new physics through single top quark processes and probing exotic top quark decays at the upgraded Tevatron.