Study of f 0(980) and f 0(1500) from B s →f 0(980)π,f 0(1500)π decays

In this paper, we analyze the scalar mesons f ₀(980) and f ₀(1500) from the decays $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0},\allowbreak f_{0}(1500)\pi^{0}$ within Perturbative QCD approach. From the leading-order calculations, we find that (a) in the allowed mixing angle ranges, the branching ratio of $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0}$ is about (1.0～1.6)×10^?7, which is smaller than that of $\bar{B}^{0}_{s}\to f_{0}(980)K^{0}$ (the difference is a few times even one order); (b) the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ is better to distinguish between the lowest lying state or the first excited state for f ₀(1500), because the branching ratios for two scenarios have about one-order difference in most of the mixing angle ranges; and (c) the direct CP asymmetries of $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ for two scenarios also exists great difference. In scenario II, the variation range of the value ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ according to the mixing angle in scenario II is very small, except for the values for mixing angles near 90° or 270°, while the variation range of ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ in scenario I is very large. Compared with the future data for the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ , it is easy to determine the nature of the scalar meson f ₀(1500).     

Study of scalar meson f 0(980) from B→f 0(980)K * decays

We show how parton distributions unintegrated over the parton transverse momentum, k _t , may be generated, at NLO accuracy, from the known integrated (DGLAP-evolved) parton densities determined from global data analyses. A few numerical examples are given, which demonstrate that sufficient accuracy is obtained by keeping only the LO splitting functions together with the NLO integrated parton densities. However, it is important to keep the precise kinematics of the process, by taking the scale to be the virtuality rather than the transverse momentum, in order to be consistent with the calculation of the NLO splitting functions.     

Search for e + e − → f 0(600)γ, f 0(980)γ, f 0(1350)γ, and f 2(1270)γ processes in the energy range from 1.05 to 1.38 GeV

In the energy range from 1.05 to 1.38 GeV, the upper limits for the cross sections of e ⁺ e ^? → f ₀(600)γ, f ₀(980)γ, f ₀(1350)γ, and f ₂(1270)γ → π⁰π⁰γ processes have been established. Measurements are performed in accordance with the statistics gathered in experiment with a spherical neutral detector (SND) on the VEPP-2M e ⁺ e ^? collider. The resultant upper limits vary from 6 to 42 pb depending on the energy and the model.     

中性张量介子f2(1270),f′2(1525)和胶球候选者ξ(2230)的混合

假定ξ(2230)的自旋宇称为2++,研究了中性张量介子f2(1270), f′ 2(1525)和胶球候选者ξ(2230)的混合,通过对可得到的这3个态的衰变数据的拟合,得到了这3个态的夸克和胶球内容. 并给出了一些关于ξ(2230)衰变的预言.     

关于Eu2+的f—f跃迁

文章综述了Eu2+在某些基质化合物中的f-f跃迁.在考察文献数据基础上,总结出Eu2+在氟化物(或氧化物)中产生f-f跃迁的某些规律性,并根据电负性、配位数及离子半径等提出一种判断Eu2+产生尖峰结构光谱的经验方法.在缺少结晶学数据情况下,该方法有可能用来预测Eu2+产生线状峰的新基质化合物.镧系离子的电子结构早已为人们所熟知.三价铕离子(Eu3+),有六个自旋平行的4f电子[1、2、3].根据洪德规则,Eu3+很容易变成Eu2+,4f壳层呈现半充满状态(4f7),获得与Gd3+具有相同的电子构型,从而趋于稳定.     

Are f(R) dark energy models cosmologically viable?

All f(R) modified gravity theories are conformally identical to models of quintessence in which matter is coupled to dark energy with a strong coupling. This coupling induces a cosmological evolution radically different from standard cosmology. We find that, in all f(R) theories where a power of R is dominant at large or small R (which include most of those proposed so far in the literature), the scale factor during the matter phase grows as t(1/2) instead of the standard law t(2/3). This behavior is grossly inconsistent with cosmological observations (e.g., Wilkinson Microwave Anisotropy Probe), thereby ruling out these models even if they pass the supernovae test and can escape the local gravity constraints.     

Determination of f(s)/f(d) for 7 TeV pp collisions and measurement of the B0→D-K+ branching fraction

The relative abundance of the three decay modes B(0)→D(-)K(+), B(0)→D(-)π(+), and B(s)(0)→D(s)(-)π(+) produced in 7 TeV pp collisions at the LHC is determined from data corresponding to an integrated luminosity of 35 pb(-1). The branching fraction of B(0)→D(-)K(+) is found to be B(B(0)→D(-)K(+)) = (2.01 ± 0.18(stat) ± 0.14(syst)) × 10(-4). The ratio of fragmentation fractions f(s)/f(d) is determined through the relative abundance of B(s)(0)→D(s)(-)π(+) to B(0)→D(-)K(+) and B(0)→D(-)π(+), leading to f(s)/f(d) = 0.253 ± 0.017 ± 0.017 ± 0.020, where the uncertainties are statistical, systematic, and theoretical, respectively.     

Fiber-based multiple-access frequency synchronization via 1f–2f dissemination

Considering the reference frequency dissemination requirements of the Square Kilometre Array telescope(SKA)project,on the basis of the 1f–2f precision frequency synchronization scheme,we propose and demonstrate a fiber-based multiple-access frequency synchronization scheme.The dissemination reference frequency can be recovered at arbitrary nodes along the entire fiber link.It can be applied to antennas close proximity to the SKA central station,and will lead to a better SKA frequency synchronization network.As a performance test,we recover the disseminated 100-MHz reference frequency at an arbitrary node chosen as being 5 km away from the transmitting site.Relative frequency stabilities of2.0×10~(-14)/s and 1.6×10~(-16)/10~4 s are obtained.We also experimentally verify the feasibility of a frequency dissemination link with three access points.     

Observation of B(s)⁰→J/ψf₀(980) and evidence for B(s)⁰→J/ψf₀(1370)

We report the observation of B(s)?→J/ψf?(980) and evidence for B(s)?→J/ψf?(1370), which are CP eigenstate decay modes. These results are obtained from 121.4 fb?1 of data collected at the Υ(5S) resonance with the Belle detector at the KEKB e(+)e? collider. We measure the branching fractions B(B(s)?→J/ψf?(980); f?(980)→π(+)π?)=(1.16(-0.19)(+0.31)(stat)(-0.17)(+0.15)(syst)(-0.18)(+0.26)(N(B(s)((*))B(s)((*)))))×10?? with a significance of 8.4σ, and B(B(s)?→J/ψf?(1370); f?(1370)→π(+)π?)=(0.34(-0.14)(+0.11)(stat)(-0.02)(+0.03)(syst)(-0.05)(+0.08)(N(B(s)((*))B(s)((*)))))×10?? with a significance of 4.2σ. The last error listed is due to uncertainty in the number of produced B(s)((*))B(s)((*)) pairs.     

Behavior of Anisotropic Compact Stars in f(R, ?) Gravity

The aim of this paper is to investigate modified f(R, ?) theory of gravity, where R and ? represent the Ricci scalar and scalar potential respectively. Specifically, we take the spherically symmetric spacetime to discuss the possible emergence of compact stars. We study the physical behavior of compact stars by considering 4 U 1820-30, SAX J1808-3658 and Her X1, which are three popular models of compact stars. The graphical analysis of energy density, radial pressure, tangential pressure, energy conditions as well as stability of compact stars has been shown. It is concluded that behavior of these three stars is usual for f(R, ?) gravity models with some specific choices of model parameters.     

On the Experimental Determination of 4f–4f Intensity Parameters from the Emission Spectra of Europium (III) Compounds

Optics and Spectroscopy - Eu3+ complexes and specially β-diketonate compounds are well known and studied in several areas due to their luminescence properties, such as sensors and lightning...     

f0(975)和φ(1020)介子对中子星物质的影响

利用相对论平均场理论,考虑了σ*,φ介子及重子八重态{N,P,A,∑-,∑0,∑ ,(I)-,(I)0},研究了中子星的性质.发现当考虑了σ*,φ介子的贡献时,超子出现的临界重子数密度降低了,超子数目增加了,超子星的转变密度ρ0H降低了,物态方程变软,最大质量变小而相应的中子星半径增大,中子星的中心重子数密度、中心能量密度和中心压强均降低.     

Bianchi Type-V Cosmology in f(R,T) Gravity with Λ(T)

A new class of cosmological models in f(R,T) modified theories of gravity proposed by Harko et al. (Phys. Rev. D 84:024020, 2011), where the gravitational Lagrangian is given by an arbitrary function of Ricci scalar R and the trace of the stress-energy tensor T, have been investigated for a specific choice of f(R,T)=f ₁(R)+f ₂(T) by considering time dependent deceleration parameter. The concept of time dependent deceleration parameter (DP) with some proper assumptions yield the average scale factor $a(t) = \sinh^{\frac{1}{n}}(\alpha t)$ , where n and α are positive constants. For 0<n≤1, this generates a class of accelerating models while for n>1, the models of universe exhibit phase transition from early decelerating phase to present accelerating phase which is in good agreement with the results from recent astrophysical observations. Our intention is to reconstruct f(R,T) models inspired by this special law for the deceleration parameter in connection with the theories of modified gravity. In the present study we consider the cosmological constant Λ as a function of the trace of the stress energy-momentum-tensor, and dub such a model “Λ(T) gravity” where we have specified a certain form of Λ(T). Such models may display better uniformity with the cosmological observations. The statefinder diagnostic pair {r,s} parameter has been embraced to characterize different phases of the universe. We also discuss the physical consequences of the derived models.     

Radiative decays and quark content of f 0(980) and φ(1020)

The quark structure of φ(1020) and f ₀(980) is studied on the basis of data on the radiative decays φ(1020) → γπ ⁰, γη, γη′, γ a ₀(980), γ f ₀(980) and f ₀(980) → γγ. The partial widths are calculated under the assumption that all the mesons under consideration are $\bar qq$ states: φ(1020) is a dominantly $s\bar s$ state ( $\eta ' = n\bar nsin\theta + s\bar scos\theta $ component contributes not more than 1%); η, η′, and π ⁰ are standard $q\bar q$ states, $\eta = n\bar ncos\theta - s\bar ssin\theta $ and $\eta ' = n\bar nsin\theta + s\bar scos\theta $ with θ?37°; and f ₀(980) is a e5 meson with the flavor wave function $n\bar ncos\varphi + s\bar ssin\varphi $ . The transition φ → γπ ⁰ specifies the admixture of the $n\bar n$ component in the φ meson: it is on the order of 0.5%. We argue that this order of $n\bar n$ value does not contradict data on the decay φ(1020) → γ a ₀(980). The partial widths calculated for the decays φ → γη, γη? are in reasonable agreement with experimental data. The measured branching-ratio value Br(φ→γf ₀(980))=(3.4±0.4 _?0.5 ^+1.5 ×10^?4) requires 25°≤|?|≤90°. For the decay f ₀(980) → γγ, the agreement with data, Γ(f ₀(980) → γγ)=0.28 _?0.13 ^+0.09 keV, is attained at either ?=85°±8° or ?=?46°±8°. A simultaneous analysis of the decays φ(1020) → γ f ₀(980) and f ₀(980) → γγ favors the solution with the negative mixing angle of ?=?48°±6°, setting f ₀(980) very close to the flavor octet (? _octet=±54.7°).     

球坐标和柱坐标下▽f、▽·(fg)、▽×(fg)、▽~2f的运算公式

找出球坐标、柱坐标各单位矢的微分运算规则 ,并进一步得出球坐标、柱坐标下 f、 ·(fg)、 ×(fg)、 2 f的方便而又严格的运算公式 .这些公式还可推广到更高阶张量的微分运算 ,因而具有普遍意义