分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-26
摘要: In S- and D-wave mixing scheme, the branching ratio of ψ″→ρπ is estimated. Together with the continuum cross section of ρπ estimated by form factor, the observed cross section of ρπ production at ψ″ in e+e− experiment is calculated taking into account the interference effect between the resonance and continuum amplitudes and the initial state radiative correction. The behavior of the cross section reveals that the disappearance of ρπ signal just indicates the existence of the corresponding branching ratio Bψ″→ρπ at the order of 10−4.
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-27
摘要: In this paper we simultaneously explain the excesses of the 750 GeV diphoton, muon g-2 and h→μτ in an extension of the two-Higgs-doublet model (2HDM) with additional vector-like fermions and a CP-odd scalar singlet ( P ) which is identified as the 750 GeV
分类: 物理学 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-26
摘要: Adding to the long standing “ρπ puzzle” in ψ′and J/ψ decays, recently BEijing Spectrometer (BES) reported B(ψ′→ K0SK0L) which is enhanced relative to the pQCD “12% rule” expectation from B(J/ψ → K0SK0L). If the enhancement is due to the mixing of the S- and D-wave charmonium states as in the ρπ case, the newly measured B(ψ′ → K0SK0L) gives a constraint on B(ψ″ → K0SK0L).It erves as a good test for the scenario of the S- and D-wave mixing in the ψ′and ψ″.
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 >> 凝聚态:结构、力学和热性能 提交时间: 2017-03-26
摘要: Multiple solutions exist in many experimental situations when several interfering amplitudes are summed to fit experimentally measured distributions, such as cross sections, mass spectra, and/or the angular distributions. We show a few examples where multiple solutions are found, but only one solution is reported in the publications. Since there is no standard rule for choosing one among the solutions as the physics one, we propose a simple rule that agrees with what has been adopted in previous literatures: the solution corresponding to the minimal magnitudes of the amplitudes must be the physical solution. We suggest test this rule in the future analyses.
分类: 物理学 >> 核物理学 提交时间: 2016-09-09
摘要: We report a new measurement of electron antineutrino disappearance using the fully-constructed Daya Bay Reactor Neutrino Experiment. The final two of eight antineutrino detectors were installed in the summer of 2012. Including the 404 days of data collected from October 2012 to November 2013 resulted in a total exposure of 6.9×105 GWth-ton-days, a 3.6 times increase over our previous results. Improvements in energy calibration limited variations between detectors to 0.2%. Removal of six 241Am-13C radioactive calibration sources reduced the background by a factor of two for the detectors in the experimental hall furthest from the reactors. Direct prediction of the antineutrino signal in the far detectors based on the measurements in the near detectors explicitly minimized the dependence of the measurement on models of reactor antineutrino emission. The uncertainties in our estimates of sin22θ13 and |Δm2ee| were halved as a result of these improvements. Analysis of the relative antineutrino rates and energy spectra between detectors gave sin22θ13=0.084±0.005 and |Δm2ee|=(2.42±0.11)×10−3 eV2 in the three-neutrino framework.
分类: 物理学 >> 核物理学 提交时间: 2016-09-05
摘要: The Daya Bay Reactor Neutrino Experiment discovered an unexpectedly large neutrino oscillation related to the mixing angle θ13 in 2012. This finding paved the way to the next generation of neutrino oscillation experiments. In this article, we review the history, featured design, and scientific results of Daya Bay. Prospects of the experiment are also described.
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: 2016-09-14
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 >> 核物理学 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: The relation between the vector-isoscalar and vector-isovector interactions in the two-flavor Nambu-Jona-Lasinio (NJL) model is investigated under the different constraints from QCD. We demonstrate that the flavor-mixing can be induced by the mismatched vector-isoscalar and vector-isovector interactions at finite baryon chemical potential and isospin chemical potential I. The effect of this non-anomaly flavor-mixing on the possible separate chiral transitions at nonzero I is studied under the assumption of the effective restoration of U(1)A symmetry. We find that for the weak isospin asymmetry, the two separate phase boundaries found previously can be converted into one only if the vector-isovector coupling gvv is significantly stronger than the vector-isoscalar one gvs without the axial anomaly.
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: 2017-11-29
摘要: We present an improved digital phase generated carrier (PGC)algorithm based on the synchronous carrier restoration(SCR) method to mitigate the carrier phase delay effects. The most distinguishing feature of this method is that it picks up the carrier signal information (frequency and phase) from the interference signal directly and accomplishes the processing of carrier signal restoration synchronically. In comparison with the traditional one which adopts the initial carrier signal, the total-harmonic-distortions of the SCR method is only 0.091%, lower than the traditional one's 18.38%, and the signal-to-noise-ratio increases 29 dB. Further, we derive the analytic expression of distortion component and verify it by experiments. Thistechnique may be potentially applied in a long distance large-scale distributed fiber-optic interferometer sensors array.
分类: 物理学 >> 核物理学 提交时间: 2016-09-18
摘要: Behind the observed pattern of lepton flavor mixing is a partial or approximate mu-tau flavor symmetry --- a milestone on our road to the true origin of neutrino masses and flavor structures. In this review article we first describe the features of mu-tau permutation and reflection symmetries, and then explore their various consequences on model building and neutrino phenomenology. We pay particular attention to soft mu-tau symmetry breaking, which is crucial for our deeper understanding of the fine effects of flavor mixing and CP violation.
分类: 物理学 >> 核物理学 提交时间: 2024-01-09
摘要: In nuclear reactors, temperature fluctuations of fluids may cause fatigue damage to adjacent structures; this is referred to as thermal striping. Research on thermal striping in the upper plenum has mainly focused on fluid fields. Few experimental studies have been reported on solid structures in a fluid field with a coaxial jet. This study entailed an experimental study of the temperature fluctuations in the fluid and on a plate surface caused by a coaxial jet. The temperature fluctuations of the fluid and plate surfaces located at different heights were analyzed. The cause of the temperature fluctuation was analyzed using a transient temperature distribution. The results show that the mixing of the hot and cold fluids gradually becomes uniform in the positive axial direction. The average surface temperatures tended to be consistent. When the jet reaches the plate surface, the swing of the jet center, contraction and expansion of the cold jet, and changes in the jet shape result in temperature fluctuations. The intensity of the temperature fluctuation was affected by the position. More attention should be paid when the plate is located at a lower height, and between the hot and cold-fluid nozzles.In nuclear reactors, temperature fluctuations of fluids may cause fatigue damage to adjacent structures; this is referred to as thermal striping. Research on thermal striping in the upper plenum has mainly focused on fluid fields. Few experimental studies have been reported on solid structures in a fluid field with a coaxial jet. This study entailed an experimental study of the temperature fluctuations in the fluid and on a plate surface caused by a coaxial jet. The temperature fluctuations of the fluid and plate surfaces located at different heights were analyzed. The cause of the temperature fluctuation was analyzed using a transient temperature distribution. The results show that the mixing of the hot and cold fluids gradually becomes uniform in the positive axial direction. The average surface temperatures tended to be consistent. When the jet reaches the plate surface, the swing of the jet center, contraction and expansion of the cold jet, and changes in the jet shape result in temperature fluctuations. The intensity of the temperature fluctuation was affected by the position. More attention should be paid when the plate is located at a lower height, and between the hot and cold-fluid nozzles.
分类: 生物学 >> 植物学 >> 应用植物学 提交时间: 2020-05-31 合作期刊: 《干旱区科学》
摘要: Tamarix taklamakanensis, a dominant species in the Taklimakan Desert of China, plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability. This study aimed to determine the water use strategies of T. taklamakanensis in the Taklimakan Desert under a falling groundwater depth. Four typical T. taklamakanensis nabkha habitats (sandy desert of Tazhong site, saline desert-alluvial plain of Qiemo site, desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site) were selected with different climate, soil, groundwater and plant cover conditions. Stable isotope values of hydrogen and oxygen were measured for plant xylem water, soil water (soil depths within 0–500 cm), snowmelt water and groundwater in the different habitats. Four potential water sources for T. taklamakanensis, defined as shallow, middle and deep soil water, as well as groundwater, were investigated using a Bayesian isotope mixing model. It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation, but through the river runoff from snowmelt water in the nearby mountain ranges. The surface soil water content was quickly depleted by strong evaporation, groundwater depth was relatively shallow and the height of T. taklamakanensis nabkha was relatively low, thus T. taklamakanensis primarily utilized the middle (23%±1%) and deep (31%±5%) soil water and groundwater (36%±2%) within the sandy desert habitat. T. taklamakanensis mainly used the deep soil water (55%±4%) and a small amount of groundwater (25%±2%) within the saline desert-alluvial plain habitat, where the soil water content was relatively high and the groundwater depth was shallow. In contrast, within the desert-oasis ecotone in the Qira and Aral sites, T. taklamakanensis primarily utilized the deep soil water (35%±1% and 38%±2%, respectively) and may also use groundwater because the height of T. taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low, which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities. Consequently, T. taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources (deep soil water and groundwater), reflecting its adaptations to the different habitats in the arid desert environment. These findings improve our understanding on determining the water sources and water use strategies of T. taklamakanensis in the Taklimakan Desert.
分类: 环境科学技术及资源科学技术 >> 环境科学技术基础学科 提交时间: 2020-04-23 合作期刊: 《干旱区科学》
摘要: Tamarix taklamakanensis, a dominant species in the Taklimakan Desert of China, plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability. This study aimed to determine the water use strategies of T. taklamakanensis in the Taklimakan Desert under a falling groundwater depth. Four typical T. taklamakanensis nabkha habitats (sandy desert of Tazhong site, saline desert-alluvial plain of Qiemo site, desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site) were selected with different climate, soil, groundwater and plant cover conditions. Stable isotope values of hydrogen and oxygen were measured for plant xylem water, soil water (soil depths within 0–500 cm), snowmelt water and groundwater in the different habitats. Four potential water sources for T. taklamakanensis, defined as shallow, middle and deep soil water, as well as groundwater, were investigated using a Bayesian isotope mixing model. It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation, but through the river runoff from snowmelt water in the nearby mountain ranges. The surface soil water content was quickly depleted by strong evaporation, groundwater depth was relatively shallow and the height of T. taklamakanensis nabkha was relatively low, thus T. taklamakanensis primarily utilized the middle (23%±1%) and deep (31%±5%) soil water and groundwater (36%±2%) within the sandy desert habitat. T. taklamakanensis mainly used the deep soil water (55%±4%) and a small amount of groundwater (25%±2%) within the saline desert-alluvial plain habitat, where the soil water content was relatively high and the groundwater depth was shallow. In contrast, within the desert-oasis ecotone in the Qira and Aral sites, T. taklamakanensis primarily utilized the deep soil water (35%±1% and 38%±2%, respectively) and may also use groundwater because the height of T. taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low, which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities. Consequently, T. taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources (deep soil water and groundwater), reflecting its adaptations to the different habitats in the arid desert environment. These findings improve our understanding on determining the water sources and water use strategies of T. taklamakanensis in the Taklimakan Desert.
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 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: Top squark (stop) plays a key role in the radiative stability of the Higgs boson mass in supersymmetry (SUSY). In this work, we use the LHC Run-1 data to determine the lower mass limit of the right-handed stop in a natural SUSY scenario, where the higgsin
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: Cosmic ray anomalies observed by PAMELA and Fermi-LAT experiments may be interpreted by heavy (TeV-scale) dark matter annihilation enhanced by Sommerfeld effects mediated by a very light (sub-GeV) U(1)_X gauge boson, while the recent direct searches from
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 embed the minimal left-right model SU(2)_L\times SU(2)_R\times U(1)_{B-L} into an SU(4)_W gauge group, and break the unified group via five-dimensional S^1/(Z_2\times Z_2) orbifolding. Leptons are fitted into SU(4)_W multiplets and located on a symmetr
分类: 物理学 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-27
摘要: A radiative natural SUSY spectrum are proposed in the deflected anomaly mediation scenario with general messenger-matter interactions. Due to the contributions from the new interactions, positive slepton masses as well as a large |Att_{t} | term can natur