Measurement of Lifetime and Decay-Width Difference in B_{s};{0}-->J/psivarphi Decays

We measure the mean lifetime tau=2/(Gamma_{L}+Gamma_{H}) and the decay-width difference DeltaGamma=Gamma_{L}-Gamma_{H} of the light and heavy mass eigenstates of the B_{s}{0} meson, B_{sL}{0} and B_{sH}{0}, in B_{s}{0}-->J/psivarphi decays using 1.7 fb;{-1} of data collected with the CDF II detector at the Fermilab Tevatron pp[over ] collider. Assuming CP conservation, a good approximation for the B_{s}{0} system in the standard model, we obtain DeltaGamma=0.076_{-0.063}{+0.059}(stat)+/-0.006(syst) ps{-1} and tau=1.52+/-0.04(stat)+/-0.02(syst) ps, the most precise measurements to date. Our constraints on the weak phase and DeltaGamma are consistent with CP conservation.     

A stochastic model for metabolizing systems with computer simulation

A stochastic model for a first-order metabolizing system which was studied in the deterministic sense by Branson and others is formulated and a detailed study of the random integral equation arising in the probabilistic model is presented. The equation is used to describe the evolution in time of the amount of metabolite present in the system. Specifically we present a study of the random integral equation of the Volterra type given by $$M\left( {t; \omega } \right) = M\left( {0; \omega } \right)e^{ - et} + \int_0^t {R\left( {\tau ; \omega } \right) e^{ - e\left( {t - \tau } \right)} d\tau , } t \geqslant 0$$ whereM(t; ω) is an unknown random function giving the amount of metabolite in the system at time t ≥ 0. This equation can be expressed in the general form $$x\left( {t; \omega } \right) = h\left( {t; \omega } \right) + \int_0^t {k\left( {t, \tau ; \omega } \right) f\left( {\tau , x\left( {\tau ; \omega } \right)} \right) d\tau } t \geqslant 0$$ which is of a type whose theoretical aspects have recently been studied by the present authors using as a basis the techniques of probabilistic functional analysis. Conditions are derived under which there exists a unique random solution to the above equation. The usefulness of the model is illustrated using computer simulation by considering a one-organ model, an organ-heart model, and a multicompartment model.     

Looking for new physics in leptonic and semileptonic decays of <Emphasis Type="Italic">B</Emphasis>-meson

We probe possible new physics (NP) effects beyond the standard model (SM) in the decays \({\overline B ^0} \to \pi \tau \overline \upsilon ,{\overline B ^0} \to \rho \tau \overline \upsilon ,and{\overline B ^0} \to \tau \overline \upsilon \), based on an effective Hamiltonian including non-SM operators. Experimental constraints on different NP scenarios are provided by recent measurements of the ratios \({{R\left( {{D^{\left( * \right)}}} \right) \equiv B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\tau \overline \upsilon } \right)} \mathord{\left/ {\vphantom {{R\left( {{D^{\left( * \right)}}} \right) \equiv B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\tau \overline \upsilon } \right)} {B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\mu \overline \upsilon } \right)}}} \right. \kern-\nulldelimiterspace} {B\left( {{{\overline B }^0} \to {D^{\left( * \right)}}\mu \overline \upsilon } \right)}}\), as well as the branching \(B\left( {{B^ - } \to \tau \overline \upsilon } \right)\). The corresponding hadronic form factors and leptonic decay constants are calculated in the covariant confined quark model developed by us.     

Laboratory demonstration of geopotential measurement using transportable optical clocks

We report an experimental demonstration of geopotential difference measurement using a pair of transportable $^{40}$Ca$^{+}$ optical clocks (TOC-729-1 and TOC-729-3) in the laboratory, each of them has an uncertainty of $1.3 \times 10^{-17}$ and an instability of $4.8 \times 10^{-15}/\sqrt{ \tau } $. Referenced to a stationary clock of TOC-729-1, the geopotential difference measurements are realized by moving TOC-729-3 to three different locations and the relevant altitude differences are measured with uncertainties at the level of 20 cm. After correcting the systematic shifts (including gravitational red shift), the two-clock frequency difference is measured to be $-0.7(2.2) \times 10^{-17}$, considering both the statistic $(1.0 \times 10^{-17})$ and the systematic $(1.9 \times 10^{-17})$ uncertainties. The frequency difference between these two clocks is within their respective uncertainties, verifying the reliability of transportable $^{40}$Ca$^{+}$ optical clocks at the low level of 10$^{-17}$.     

Study of semileptonic decay of ${\bar{B}}_{s}^{0} \rightarrow \phi {l}^{+}{l}^{-}$ in QCD sum rule

In this work we study the semileptonic decay of ${\bar{B}}_{s}^{0}\to \phi {l}^{+}{l}^{-}$ (l=e, μ, τ) with the QCD sum rule method. We calculate the ${\bar{B}}_{s}^{0}\to \phi $ translation form factors relevant to this semileptonic decay, then the branching ratios of ${\bar{B}}_{s}^{0}\to \phi {l}^{+}{l}^{-}$ (l=e, μ, τ) decays are calculated with the form factors obtained here. Our result for the branching ratio of ${\bar{B}}_{s}^{0}\to \phi {\mu }^{+}{\mu }^{-}$ agree very well with the recent experimental data. For the unmeasured decay modes such as ${\bar{B}}_{s}^{0}\to \phi {e}^{+}{e}^{-}$ and ${\bar{B}}_{s}^{0}\to \phi {\tau }^{+}{\tau }^{-}$, we give theoretical predictions.     

Enhanced interface properties of diamond MOSFETs with Al_2O_3 gate dielectric deposited via ALD at a high temperature

The interface state of hydrogen-terminated(C–H) diamond metal–oxide–semiconductor field-effect transistor(MOSFET) is critical for device performance. In this paper, we investigate the fixed charges and interface trap states in C–H diamond MOSFETs by using different gate dielectric processes. The devices use Al_2O_3 as gate dielectrics that are deposited via atomic layer deposition(ALD) at 80℃ and 300℃, respectively, and their C–V and I–V characteristics are comparatively investigated. Mott–Schottky plots(1/C~2–VG) suggest that positive and negative fixed charges with low density of about 1011 cm~(-2) are located in the 80-℃-and 300-℃ deposition Al_2O_3 films, respectively. The analyses of direct current(DC)/pulsed I–V and frequency-dependent conductance show that the shallow interface traps(0.46 e V–0.52 e V and0.53 e V–0.56 e V above the valence band of diamond for the 80-℃ and 300-℃ deposition conditions, respectively) with distinct density(7.8 × 10~(13) e V~(-1)·cm~(-2)–8.5 × 10~(13) e V-1·cm~(-2) and 2.2 × 1013 e V~(-1)·cm~(-2)–5.1 × 10~(13) e V~(-1)·cm~(-2) for the80-℃-and 300-℃-deposition conditions, respectively) are present at the Al_2O_3/C–H diamond interface. Dynamic pulsed I–V and capacitance dispersion results indicate that the ALD Al_2O_3 technique with 300-℃ deposition temperature has higher stability for C–H diamond MOSFETs.     

Observation of B(0)-->D(*-)tau(+)nu(tau) decay at Belle

We report an observation of the decay B{0}-->D{*-}tau{+}nu{tau} in a data sample containing 535x10{6} BB pairs collected with the Belle detector at the KEKB asymmetric-energy e{+}e{-} collider. We find a signal with a significance of 5.2sigma and measure the branching fraction B(B{0}-->D{*-}tau{+}nu{tau})=(2.02{-0.37}{+0.40}(stat)+/-0.37(syst))%. This is the first observation of an exclusive B decay with a b-->ctaunu{tau} transition.     

Measurement of the ∑± lifetimes

From about 2 × 10⁶ measured ∑^± decay's produced by stoppingK ^? mesons in the 81 cm Saclay hydrogen bubble chamber about 140,000 ∑^? →n π^? and 20,000 ∑⁺ →nπ⁺ decays were selected for a lifetime measurement. We obtained: $$\begin{gathered} \tau _{\Sigma ^ + } = (0.795 \pm 0.010) \times 10^{ - 10} \sec \hfill \\ \tau _{\Sigma ^ - } = (1.485 \pm 0.022) \times 10^{ - 10} \sec . \hfill \\ \end{gathered} $$      

Accurate statistics of a flexible polymer chain in shear flow

We present exact and analytically accurate results for the problem of a flexible polymer chain in shear flow. Under such a flow the polymer tumbles, and the probability distribution of the tumbling times tau of the polymer decays exponentially as approximately exp(-alphatau/tau_{0}) (where tau_{0} is the longest relaxation time). We show that for a Rouse chain this nontrivial constant alpha can be calculated in the limit of a large Weissenberg number (high shear rate) and is in excellent agreement with our simulation result of alpha approximately 0.324. We also derive exactly the distribution functions for the length and the orientational angles of the end-to-end vector R of the polymer.     

New criterion for comparison of classical theory of nucleation in superheated liquids with experimental data

We have obtained inequality $ 1 - {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} < \left( {J \cdot V \cdot \bar \tau } \right)^{ - 1} < 1 + {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} $ 1 - {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} < \left( {J \cdot V \cdot \bar \tau } \right)^{ - 1} < 1 + {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} , where J is the frequency of homogeneous nucleation, V and $ \bar \tau $ \bar \tau are, respectively, volume and average lifetime of the superheated liquid, and $ {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} $ {{\Delta \bar \tau } \mathord{\left/ {\vphantom {{\Delta \bar \tau } {\bar \tau }}} \right. \kern-\nulldelimiterspace} {\bar \tau }} is relative statistical error $ \bar \tau $ \bar \tau . Inequality appears to be a consequence of nucleation homogeneity and stability used at its deduction and taken in the theory as initial and determinant assumption. Calculations with the use of experimental data for the boundaries of the attainable superheating show that inequality is not satisfied. Thus, experimental data can not be considered a proof of the theory fundamentals.     

Electron tunnelling phase time and dwell time through an associated delta potential barrier

The electron tunnelling phase time τP and dwell time τD through an associated delta potential barrier U(x) = ξδ(x) are calculated and both are in the order of 10^-17～10^-16s. The results show that the dependence of the phase time on the delta barrier parameter ξ can be described by the characteristic length lc = h^2/meξ and the characteristic energy Ec=meξ^2/h^2 of the delta barrier, where me is the electron mass, lc and Ec are assumed to be the effective width and height of the delta barrier with lcEc=ξ, respectively. It is found that TD reaches its maximum and τD = τp as the energy of the tunnelling electron is equal to Ec/2, i.e. as lc =λDB, λDB is de Broglie wave length of the electron.     

Preferential attachment network model with aging and initial attractiveness

In this paper, we generalize the growing network model with preferential attachment for new links to simultaneously include aging and initial attractiveness of nodes. The network evolves with the addition of a new node per unit time, and each new node has m new links that with probability Π_i are connected to nodes i already present in the network. In our model, the preferential attachment probability Π_i is proportional not only to k_i + A, the sum of the old node i's degree k_i and its initial attractiveness A, but also to the aging factor ${\tau }_{i}^{-\alpha }$, where τ_i is the age of the old node i. That is, ${{\rm{\Pi }}}_{i}\propto ({k}_{i}+A){\tau }_{i}^{-\alpha }$. Based on the continuum approximation, we present a mean-field analysis that predicts the degree dynamics of the network structure. We show that depending on the aging parameter α two different network topologies can emerge. For α < 1, the network exhibits scaling behavior with a power-law degree distribution P(k) ∝ k^−γ for large k where the scaling exponent γ increases with the aging parameter α and is linearly correlated with the ratio A/m. Moreover, the average degree k(t_i, t) at time t for any node i that is added into the network at time t_i scales as $k({t}_{i},t)\propto {t}_{i}^{-\beta }$ where 1/β is a linear function of A/m. For α > 1, such scaling behavior disappears and the degree distribution is exponential.     

Tau Leptonic Decay τ→lVlVτ in Littlest Higgs Model＊

We consider the τ leptonic decay $\tau\rightarrow l\bar{\nu}_{l}\nu_{\tau}$ in the framework of the littlest Higgs (LH) model and calculate the corrections of new particles to this decay. We find that the contributions of the charged scalars can be safely ignored and the LH model is in perfect agreement with the universality of the couplings of the SU gauge bosons to the leptonic charged currents. The corrections of the LH model to the τ leptonic decay $\tau\rightarrow l\bar{\nu}_{l}\nu_{\tau}$ are not sensitive to the parameter c, but depend strongly on the parameters f and x. The precision measured data about the τ leptonic decay demand that the parameter f approximately equal 3.5 TeV and x>0.1, while agree with the general expectation based on other phenomenological explorations.     

Calculation of the Width of the τ → K–K 0 ντ Decay in the Extended Nambu–Jona-Lasinio Model with Estimation of the Contribution from the Final-State Interaction

JETP Letters - The partial width of the $$\tau \to {{K}^{ - }}{{K}^{0}}{{\nu }_{\tau }}$$ decay has been calculated within the extended Nambu–Jona-Lasinio model including the contact and...     

τ → K–π0ντ Decay in the Nambu–Jona-Lasinio Model Including the Final-State Interaction of Mesons

JETP Letters - The $$\tau \to {{K}^{ - }}{{\pi }^{0}}{{\nu }_{\tau }}$$ decay has been described within the Nambu–Jona-Lasinio model including the contact term and the contribution from an...     

Search for charged Higgs bosons at LEP in general two Higgs doublet models

A search for pair-produced charged Higgs bosons was performed in the data collected by the DELPHI detector at LEP II at centre-of-mass energies from 189 GeV to 209 GeV. Five different final states, , , , and were considered, accounting for the major expected decays in type I and type II Two Higgs Doublet Models. No significant excess of data compared to the expected Standard Model processes was observed. The existence of a charged Higgs boson with mass lower than 76.7 GeV/c² (type I) or 74.4 GeV/c² (type II) is excluded at the 95% confidence level, for a wide range of the model parameters. Model independent cross-section limits have also been calculated.Received: 30 September 2003, Revised: 12 February 2004, Published online: 8 April 2004     

The $$\tau\rightarrow\bar{K}^{*0}(892)\pi^{-}\nu_\tau$$ Decay in the Nambu–Jona-Lasinio Model

The width of the \(\tau\rightarrow\bar{K}^{*0}(892)\pi^{-}\nu_\tau\) decay is calculated within the Nambu–Jona-Lasinio model taking into account four channels of the formation of the \(\tau\rightarrow\bar{K}^{*0}(892)\pi^{-}\) pair—the contact interaction and three channels with intermediate axial-vector, vector, and pseudoscalar mesons. Leading contributions arise from the contact interaction and axial-vector channel with an intermediate ground-state K₁(1270) meson. Our theoretical estimate adequately reproduces the measured \(\tau\rightarrow\bar{K}^{*0}(892)\pi^{-}\nu_\tau\) decay width.     

W diffusion in paramagnetic and ferromagnetic <Emphasis Type="Italic">α</Emphasis>-Fe

Diffusion of W in the 723–1153 K temperature range both in paramagnetic and ferromagnetic α-Fe was studied, diffusion couples were manufactured by W evaporation onto high-purity Fe samples. Measurements were made using the Heavy Ion Rutherford Backscattering (HIRBS) technique as the analysis tool. A straight Arrhenius plot was obtained in the paramagnetic region with a break at the Curie temperature (1043 K) followed by a curved plot at lower temperatures as a product of the effect of ferromagnetism on diffusion. A straight Arrhenius plot was obtained in the paramagnetic region with a break at the Curie temperature (1043 K) followed by a curved plot at lower temperatures resulting from the effect of ferromagnetism on diffusion. A previous developed model for the diffusion of non-magnetic impurities in ferromagnetic Fe fits the data perfectly well, giving a temperature dependent diffusivity according to