Effects of vector leptoquarks onΛb→Λ,lv^-l decay

Experimental data on R(D⁺).R(K⁺),and R(J/ψ),provided by different collaborations,show sizable deviations from the standard model predictions.To describe these anomalies,many new physics scenarios have been proposed.One of them is the leptoquark model,which introduces the simultaneous coupling of vector and scalar leptoquarks to quarks and leptons.To look for similar possible anomalies in the baryonic sector,we investigate the effects of a vector leptoquark U3(3,3,2/3)on various physical quantities related to the tree-levelΛb→Λclv^-l decays(l=u,t),which proceed via b→c l v^-l transiti ons at the quark level.We calculate the differential branching ratio,forward-backward asymmetry,and longitudinal polarizations of leptons and Ac baryons at theμandτlepton channels in the leptoquark model and compare their behavior to the predictions of the SM in terms of q^2.In the calculations,we use the form factors calculated in full QCD as the main input and account for all errors coming from the form factors and model parameters.We observe that at theτchanneL the Ra fit solution to data related to the leptoquark model sweeps some regions out of the SM band;nevertheless,the fit has a considerable intersection with the SM predictions.The Rr type solution gives roughly the same results as the SM on DBR(q^2)-q^2.At theμchannel.the leptoquark model gives results that are consistent with the SM predictions and existing experimental data on the behavior of DBR(q^2)with respect to q^2.Concerning the q^2 behavior of the AFB(q^2),the two types of fits forτand the predictions at the“channel in the leptoquark model give exactly the same results as the SM.We also investigate the behavior of the parameter R(q^2)with respect to q^2 and the value of R(Λc)in both the vector leptoquark and SM models.Both fit solutions lead to results that deviate considerably from the SM predictions for R(q^2)-q^2 and R(Ac).Future experimental data on R(q^2)-q^2 and RC made available by measurements of theΛb→Λcτv^-τchannel,will be particularly helpful.Any experimental deviations from the SM predictions in this channel would emphasize the im porta nee of tree-level hadronic weak tran sitions as good probes of new physics effects beyond the SM.     

Phenomenology of b→cτ■ decays in a scalar leptoquark model

During the past few years,signs of lepton flavor universality(LFU)violation have been observed in b→cτ■ and b→sl+l-transitions.Recently,the D* and τ polarization fractions P_L~D* and P_L~τ in B→D*τ■decay were likewise measured by the Belle collaboration.Motivated by these intriguing results,we revisit the RD(*)and RK(*) anomalies in a scalar leptoquark(LQ)model,where two scalar LQs,one of which is a S U(2)L singlet and the other a S U(2)L triplet,are introduced simultaneously.We consider five b→ cτ■ mediated decays,B→D(*)τ■,B_c→ηcτ■,Bc→J/ψt■,and ∧_b→∧_cτ■,and focus on the LQ effects on the q~2 distributions of the branching fractions,LFU ratios,and various angular observables in these decays.Under the combined constraints of the available data on RD(*),RJ/ψ,P_L~τ(D*),and pLD*,we perform scans for the LQ couplings and make predictions for a number of observables.Numerically it is found that both the differential branching fractions and LFU ratios are largely enhanced by the LQ effects,with the latter expected to provide testable signatures at the SuperKEKB and High-Luminosity LHC experiments.     

Bistatic Reverberation in Shallow Water：Modelling and Data Comparison

Bistatic and monostatic reverberation data were recorded in the 2001 Asian Sea International Acoustic Experiment (ASLIAEX).A model based on the normal mode theory has been developed to calculate bistatic bottom reverberation in shallow water and to explain the recorded data.The comparisons between the monostatic and bistatic reverberation data are discussed,and the comparisons between model predictions and measured bistatic reverberation data are also presented.The numerical and experimental results show that the numerical predictions from the bistatic reverberation model fit the experimental data well,and the long-range bistatic reverberation with a time delay can be approximately expressed by the monostatic reverberation data.     

Top Quark Decay t → cb-↑b in Topcolor-Assisted Technicolor Models

The topcolor-assisted technicolor （TC2） model predicts the existence of the top-pions and the CP-even top-Higgs with large flavor-changing couplings to the top quark, which at tree-level can mediate the top quark three-body decay t → cb-↑b. We study this decay, show the dependence of the decay rate on the relevant TC2 parameters and compare the results with the predictions in the minimal supersymmetric model. We find that the decay rate in the TC2 model is much larger than that in the minimal supersymmetric model if the new particles are not too heavy. However, in consideration of the ODF and the LEP experiment limits, the top-pion mass is greater than 340 GeV in a more realistic parameter space, so the decay width of the channel t → cb-↑b intermediated by top-pions will be depressed greatly and difficult to be detected at the future collider. Thus, to observe this channel at the future collider, considering the top-higgs contribution may be the possible way when the masses of the top-pions and the top-higgs are not degenerate.     

Chiral Extrapolation of Lattice Data of Λ_b→Λ_c Form Factors

An extrapolation to the physical limit for the lattice data of Λ_b →Λ_c form factors computed in the nonphysical region is made in this work through a class of fitting functions proposed by us with nonlinear dependence on m2/π derived in the chiral perturbative theory(ChPT) and the heavy quark effective theory(HQET) framework. Then the results are applied to calculate the differential and integrated Λ_b →Λ_c semileptonic decay rates. Meanwhile, a comparison between our results and those obtained through the extrapolation functions with naive linear dependenceon m2/π is made.It is shown that the difference between the extrapolated central values of these two cases is about 5%.The total uncertainties(depending on the momentum transfer q~2) in the linear case are about 5% ～10%(caused by the uncertainties of lattice data) and those in the nonlinear case are about 10% ～ 20%(caused by the uncertainties of both lattice data and input parameters in Ch PT and HQET). More accurate lattice data and parameters in ChPT and HQET are needed to reduce the uncertainties of the extrapolated results.     

Event generators for η/η’ rare decays into π~+π~-1~+1~- and e~+e~-μ~+μ~-

Study of the rare and forbidden decays of η/η offers a sensitive probe to test fundamental symmetries of quantum chromodynamics and search for new physics beyond the Standard Model. To study the rare decays of η/η to π + π - e + e - , π + π - μ + μ - and e + e - μ + μ - at the BES detector, we developed several event generators based on the vector meson dominant model with finite-width corrections and the pseudoscalar mesons mixing theory. The various distributions from event generators are in good agreement with the theoretical predictions, which indicates that the event generators work very well after implemention in the BES Monte Carlo simulation package. In the BES physics analysis, the performance of the event generators will be improved in accordance with the distributions of different variables of η/η from data and the improvement on the theoretical calculations.     

Colorimetric characterization of liquid crystal display using an improved two-stage model

An improved two-stage model of colorimetric characterization for liquid crystal display (LCD) was proposed. The model included an S-shape nonlinear function with four coefficients for each channel to fit the Tone reproduction curve (TRC), and a linear transfer matrix with black-level correction. To compare with the simple model (SM), gam-offset-gain (GOG), S-curve and three-one-dimensional look-up tables (3-1D LUTs) models, an identical LCD was characterized and the color differences were calculated and summarized using the set of 7×7×7 digital-to-analog converter (DAC) triplets as test data. The experimental results showed that the model was outperformed in comparison with the GOG and SM ones, and near to that of the S-curve model and 3-1D LUTs method.     

Acoustic response characteristics of unsaturated porous media

By employing the plane wave analysis method, the dispersion equations associated with compressional and shear waves using Santos’s three-phase poroelastic theory were driven. Considering the reservoir pressure, the high frequency corrections and the coupling drag of two fluids in pores, the influences of frequency and gas saturation on the phase velocities and the inverse quality factors of four body waves predicted by Santos’s theory were discussed in detail. The theoretical velocities of the fast compressional and shear waves were compared with the results of the low and high frequency experiments from open publications, respectively. The results showed that they are in good agreement in the low frequency case rather than in the high frequency case. In the latter case, several popular poroelastic models were considered and compared with the experimental data. In the models, the results of White’s theory fit the experimental data, but the parameter b in White’s model has a significant impact on the results. Under the framework of the linear viscoelasticity theory, the attenuation mechanism of Santos’s model was extended, and the comparisons between the experimental and theoretical results were also made with respect to attenuation. For the case of water saturation less than 90%, the extended model makes good predictions of the inverse quality factor of shear wave. There is a significant difference between the experimental and theoretical results for the compressional wave, but the difference can be explained by the experimental data available.     

Colorimetric characterization of liquid crystal display using an improved two-stage model

An improved two-stage model of colorimetric characterization for liquid crystal display (LCD) was proposed. The model included an S-shape nonlinear function with four coefficients for each channel to fit the Tone reproduction curve (TRC), and a linear transfer matrix with black-level correction. To compare with the simple model (SM), gain-offset-gain (GOG), S-curve and three-one-dimensional look-up tables (3-1D LUTs) models, an identical LCD was characterized and the color differences were calculated and summarized using the set of 7 × 7 × 7 digital-to-analog converter (DAC) triplets as test data. The experimental results showed that the model was outperformed in comparison with the GOG and SM ones, and near to that of the S-curve model and 3-1D LUTs method.     

Study of the production of Λ_b~0 band ~0 hadrons in pp collisions and first measurement of the Λ_b~0→J/ψpK~- branching fraction

The product of the A_b~0(B~0) differential production cross-section and the branching fraction of the decay A_b~0→J/ψpK~-(B~0→J/ψK~*(892)~0) is measured as a function of the beauty hadron transverse momentum,p_T,and rapidity,y.The kinematic region of the measurements is p_T 20 GeV/c and 2.0y4.5.The measurements use a data sample corresponding to an integrated luminosity of 3fb~(-1) collected by the LHCb detector in pp collisions at centre-of-mass energies s~(1/2)=7 TeV in 2011 and s~(1/2)= 8TeV in 2012.Based on previous LHCb results of the fragmentation fraction ratio,f_∧_b~0/f_d,the branching fraction of the decay ∧_b~0→J/ψpK~- is measured to be B(∧_b~0→J/ψpK~-)=(3.17±0.04±0.07±0.34_(-0.28)~(+0.45)×10~(-4)where the first uncertainty is statistical,the second is systematic,the third is due to the uncertainty on the branching fraction of the decay B~0→J/ψK~*(892)~0,and the fourth is due to the knowledge of f_∧_b~0/f_d.The sum of the asymmetries in the production and decay between A_b and A_b~0 is also measured as a function of p_T and y.The previously published branching fraction of A_b~0→J/φpπ~-,relative to that of A_b~0→J/ψpK~-,is updated.The branching fractions of∧_b~0→P_c~+(→J/ψp)K~- are determined.     

Update of g-2 of the muon and Δα

We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions （5） 2 to the running of the QED coupling, Δαbad^5）（MZ^2）. Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV.     

Update of g-2 of the muon and △α

We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions to the running of the QED coupling,αh(5a)d(MZ2).Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2π channel and from the energy region just below 2 GeV.     

Gas flow characteristics in straight silicon microchannels

Experiments have been conducted to investigate nitrogen gas flow characteristics through four trapezoidal silicon microchannels with different hydraulic diameters. The volume flow rate and pressure ratio are measured in the experiments. It is found that the friction coefficient is no longer a constant, which is different from the conventional theory. The characteristics are first explained by the theoretical analysis. A simplified rectangular model (rectangular straight channel model) is then proposed. The experimental results are compared with the theoretical predictions based on the simplified rectangular model and the two-dimensional flow between the parallel-plate model which was usually used. The difference between the experimental data and the theoretical predictions is found in the high-pressure ratio cases. The influence of the gas compressibility effect based on the Boltzmann gas kinetic analysis method is studied to interpret the discrepancy. We discuss two important factors affecting the application extent of different prediction models.     

An analytic model for gate-all-around silicon nanowire tunneling field effect transistors

An analytical model of gate-all-around(GAA) silicon nanowire tunneling field effect transistors(NW-TFETs) is developted based on the surface potential solutions in the channel direction and considering the band to band tunneling(BTBT) efficiency. The three-dimensional Poisson equation is solved to obtain the surface potential distributions in the partition regions along the channel direction for the NW-TFET, and a tunneling current model using Kane’s expression is developed. The validity of the developed model is shown by the good agreement between the model predictions and the TCAD simulation results.     

A Micro-Mechanism Model for Porous Media

Based on the tortuous-expanding path/channel model, a micro-mechanism model for porous media is de- veloped. The proposed model is expressed as a function of tortuosity, porosity, resistance coefficient, and fluid properties. Every parameter in the proposed model has clear physical meaning. The results show that the model predictions are in good agreement with those from the existing experimental data.     

Nuclear Slope Parameter Of pp and p^-p Elastic Scattering in QCD Inspired Model

Based on the quark-gluon structure of nucleon and the possible existence of Odderon in strong interaction process due to gluon self-interaction, the elastic scatterings of pp and p^-p at high energies are studied. The contributions from individual terms of quark-quark, gluon-gluon interactions, quark-gluon interference, and the Odderon terms to the nuclear slope parameter B（s） are analyzed. Our results show that the QCD inspired model gives a good fit to the LHC experimental data of the nuclear slope parameter.     

Numerical and experimental investigation of temperature effects on the surface plasmon resonance sensor

The effects of temperature on a surface plasmon studied experimentally and theoretically. SPR resonance （SPR） sensor in Kretschmann configuration are experiments are carried out over a temperature range of 278- 313 K in steps of 5 K. A detailed theoretical model is provided to analyze the variation of performance with varying temperature of the sensing environment. The temperature dependence of the properties of the metal, dielectric, and analyte are studied, respectively. The numerical results indicate that the predictions of the theoretical model are well consistent with the experiment data.     

An improved formula for the surface resistance of normal metals at millimetre wavelengths

A number of researchers have reported discrepancies between surface resistance (SR) measurements and classical theoretical predictions in normal metals for millimetre wavelengths (MW). In this paper, a rigorous model is developed for analysing SR of normal metals. This model is based on quantum mechanical analysis of the spatial dispersion within the metal. We use the model to predict SR and eliminate the discrepancies between SR measurements and classical theoretical predictions in normal metals for MW. Moreover, we have compared the results of this model with that of the classical skin-effect model and classical relaxation-effect model. Our analysis shows that the conductivity is not only frequency- but also wave-vector-dependent for MW. We demonstrate that our model has good quantitative agreement with the published experimental data for the room temperature surface resistance of normal metals for MW.     

Prediction of heat transfer of nanofluid on critical heat flux based on fractal geometry

Analytical expressions for nucleate pool boiling heat transfer of nanofluid in the critical heat flux (CHF) region are derived taking into account the effect of nanoparticles moving in liquid based on the fractal geometry theory. The proposed fractal model for the CHF of nanofluid is explicitly related to the average diameter of the nanoparticles, the volumetric nanoparticle concentration, the thermal conductivity of nanoparticles, the fractal dimension of nanoparticles, the fractal dimension of active cavities on the heated surfaces, the temperature, and the properties of the fluid. It is found that the CHF of nanofluid decreases with the increase of the average diameter of nanoparticles. Each parameter of the proposed formulas on CHF has a clear physical meaning. The model predictions are compared with the existing experimental data, and a good agreement between the model predictions and experimental data is found. The validity of the present model is thus verified. The proposed fractal model can reveal the mechanism of heat transfer in nanofluid.