Pion Decay Constant and Masses of Light Quarks and In-medium Goldstone Bosons

Based on the fully dressed confining quark propagator, the pion decay constant fπ, local quark vacuum condensate, and the masses of light quarks and in-medlum Goldstone bosons are investigated. The pion decay constant fπ is predicted and compared with its value of experimental measurement. A great agreement is obtained. With the predicted fπ and values of Goldstone boson masses measured by experiments in free configuration the current masses of light quarks and the masses of in-medium Goldstone bosons are obtained.

Decay constants of pseudoscalar and vector mesons with improved holographic wavefunction

We calculate the decay constants of light and heavy-light pseudoscalar and vector mesons with improved soft-wall holographic wavefuntions, which take into account the effects of both quark masses and dynamical spins. We find that the predicted decay constants, especially for the ratio fV/fP, based on light-front holographic QCD, can be significantly improved, once the dynamical spin effects are taken into account by introducing the helicity-dependent wavefunctions. We also perform detailed χ2 analyses for the holographic parameters （i.e. the mass-scale parameter κ and the quark masses）, by confronting our predictions with the data for the charged-meson decay constants and the meson spectra. The fitted values for these parameters are generally in agreement with those obtained by fitting to the Regge trajectories. At the same time, most of our results for the decay constants and their ratios agree with the data as well as the predictions based on lattice QCD and QCD sum rule approaches, with only a few exceptions observed.

Relativistic studies of the decay constants of S wave and P wave mesons

Relativistic corrections are important in hadronic physics since even for the heavy hadrons there are sizable relativistic corrections. Therefore one should use a relativistic model to describe the higher excited states. This note summarizes our predictions for the decay constants of the S wave and P wave heavy mesons by means of the instantaneous relativistic Bethe Salpeter equation （Salpeter equation）.

Charmed andϕmeson decay constants from 2+1-flavor lattice QCD

On a lattice with 2+1-flavor dynamical domain-wall fermions at the physical pion mass,we calculate the decay constants of D_s^(*) , D^(*) ,and φ .The lattice size is 48^3×96 ,which corresponds to a spatial extension of -5.5 fm,with a lattice spacing of a\approx a≈0.114 fm.For the valence light,strange,and charm quarks,we use overlap fermions at several mass points close to their physical values.Our results at the physical point are f_(D)=213(5) MeV, f_(D)_(s)=249(7) MeV, f_(D)^(*)=234(6) MeV, f_(D)_(s)^(*)=274(7) MeV,and f_(D)_(s)=241(9) MeV.The couplings of D^(*) and D_s^(*) to the tensor current( f_(V)^(T) )can be derived from ratios f_(D)^(*)^T/f_(D)^(*)=0.91(4) and f_(D)_(s)^(*)^T/f_(D)_(s)^(*)=0.92(4) ,respectively,which are the first lattice quantum chromodynamics(QCD)results.We also obtain ratios f_(D)^(*)/f_(D)=1.10(3) and f_(D)_(s)^(*)/f_(D)_(s)=1.10(4) ,which reflect the size of heavy quark symmetry breaking in charmed mesons.Ratios f_(D)_(s)/f_(D)=1.16(3) and f_(D)_(s)^(*)/f_(D)^(*)=1.17(3) can be taken as a measure of SU(3)flavor symmetry breaking.

Weak decays of doubly heavy baryons:"decay constants"

Inspired by the recent observation of the ∑c^＋c^＋ by the LHCb Collaboration, we explore the ＂decay constants＂ of doubly heavy baryons in the framework of QCD sum rules. With the ∑cc,∑bb, and Ωcc,Ωbc,Ωbb baryons interpolated by three-quark operators, we calculate the correlation functions using the operator product expansion and include the contributions from operators up to dimension six. On the hadron side, we consider both contributions from the lowest-lying states with J^P 1/2^＋ and from negative parity baryons with JP=1/2^-. We find that the results are stable and the contaminations from negative parity baryons are not severe. These results are ingredients for the QCD study of weak decays and other properties of doubly-heavy baryons.

Decay constants of B_(c)(nS) and B_(c)^(*)(nS)^(*)

The decay constants of the low lying S-wave B_(c)mesons,i.e.B_(c)(nS) and B_(c)^(*)(nS) with n ≤3,are calculated in the nonrelativistic quark model.The running coupling of the strong interaction is taken into account,and the uncertainties due to varying parameters and losing Lorentz covariance are considered carefully.As a byproduct,the decay constants of the low lying S-wave charmonium and bottomium states are given in the appendixes.

Decay of Rhizophora apiculata(Blume)and Xylocarpus granatum(Koenig)detrital sources in the Sarawak Mangrove,Malaysia

Decaying mangrove detritus plays a significant role in nutrient cycling and fueling in both the forests and aquatic habitats where the detritus stems from estuarine and coastal food webs.Detrital decay rates partly depend on the type of detritus,but most studies have thus far focused on leaf litter decay and decomposition,whereas other detrital sources(except for roots)have largely been ignored.We compare the decay rates of Rhizophora apiculata and Xylocarpus granatum non-leafy detritus(flowers,propagules,stipules,and twigs)with mangrove leaf litter in field studies,using litter bags during the dry and the wet seasons in the tropical mangrove forest of Sibuti,Sarawak,Malaysia.We observed higher microbial decay rates of stipules,flowers,propagules,and twigs for both the R.apiculata and X.granatumduring the wet months.By contrast,leaf decay rates were higher during the dry months.Decay rates depended on the lignin content of the detrital sources of both species,both during dry and wet months.Accordingly,the half-life(T0.5)and 95%lifespan(T0.95)of non-leaf materials(flowers,propagules,stipules and twigs)for both species were remarkably longer than those of leaf litter.Slowly decaying non-leafy detritus may play a significant role in nutrient and carbon cycling over longer time,when leaf litter is either being decomposing rapidly and/or being washed away by tidal flush and river runoff.Hence,non-leafy(flowers,propagules,stipules and twigs)detritus should be taken into account when budgeting organic matter turnover in mangroves.

Influence of the Magnetic Field on the Transient Decay of the Density of Charge Carriers in a Silicon Photocell with Vertical Multijunctions Connected in Series Placed in Open Circuit

This study investigates the effect of the magnetic field on the transient density of excess minority charge carriers in the base of a series-connected vertical junction silicon solar cell. The solar cell is presented in open circuit transient operation. The magnetic field through the Laplace force which deflects the photogenerated carriers from their initial trajectory towards the lateral surfaces reducing their mobility, diffusion and conduction, will certainly influence the decay time of the transient regime. The transient density of excess minority carriers in the base is a sum of infinite terms whose decay time of the different harmonics is studied.

Nutrient dynamics associated with leaf litter decomposition of three agroforestry tree species (Azadirachta indica, Dalbergia sissoo, and Melia azedarach) of Bangladesh

Azadirachta indica A. Juss, Dalbergia, sissoo Roxb., and Melia azedarach L. are little studied species in nutrient return capabilities from leaf litter decomposition to maintenance of the soil fertility despite their importance in agroforestry practices of Bangladesh. A leaf litter decomposition experiment was conducted using a litterbag teeh7 nique to assess the nutrient reaun efficiency of these species. The de- composition rate of leaf litter was highest for M. azedarach and lowest for D. sissoo. Rainfall and temperature of study sites showed a significant （p〈0.05） positive relationship with the rate of leaf litter decomposition. The highest decay constant was observed for M. azedarach （6.67）. Nitrogen and Phosphorus concentration in leaf litter showed a decreased trend sharply at the end of the first month, whereas rapid decrease of Potassium concentration was reported within 10 days. Conversely, higher concentration of nutrient was observed at the later stages of decomposition. All three species showed a similar pattern of nutrient release （K 〉 N 〉 P） during the decomposition process of leaf litter. Among the studied species, D. sissoo was best in terms of N and P return and A. indica was best in terms of K return.

Experimental investigation and prediction model for UCS loss of unsaturated sandstones under freeze-thaw action

Sandstone is widely distributed in cold regions and the freeze-thaw deterioration of them has caused many geological engineering disasters.As an important and direct index of frost resistance,the strength loss of sandstones under freeze-thaw actions should be investigated to provide a guidance for the stability assessment of geological engineering.In this research,the UCS(Uniaxial compressive strength)loss of six typical sandstones with different water contents after 0,20,40 and 60 freeze-thaw cycles was measured in the laboratory.The experimental results indicated that the freeze-thaw damage was more serious in sandstones containing high water contents,and the critical saturations for causing a significant loss of UCS under freeze-thaw were 60%-80%for these sandstones.Below this critical saturation,the UCS loss of the sandstones was mainly caused by water weakening rather than freeze-thaw damage.Besides,a developed strength prediction model was proposed by combining the exponential decay function and multiple linear regression method.The initial porosity,elastic modulus and tensile strength of fresh sandstones were a good parameter combination to accurately determine the decay constant in this developed model.The main novelty of this model is that it can accurately and easily estimate the UCS loss of sandstones after any freeze-thaw cycle only using the initial parameters of fresh sandstones,but it does not need to perform freeze-thaw and mechanical strength experiments.This study not only provides an accurate prediction model of UCS under freeze-thaw,but also makes a contribution to better understanding the frost resistance mechanism of sandstones.

Litterfall,decomposition and nutrient release of Shorea robusta and Tectona grandis in a sub-tropical forest of West Bengal,Eastern India

We studied leaf litter fall, decomposition and nutrient release patterns of Shorea robusta and Tectona grandis by using a litter bag technique to better understand the release pattern of nutrients to soil from leaf litter. Annual litterfall varied from 13.40 ± 2.56 t ha-1 a-1 for S. robusta to 11.03 ± 3.72 t ha-1 a-1 for T. grandis and the decay constant （k） of decomposed leaf litter was distinctly higher for T. grandis （2.70 ± 0.50 a-1） compared to S. robusta （2.41 ±0.30 a-1）. Biomass loss was positively correlated with the initial litter C, WSC, C/N and ash content in S. robusta and N, P and K concentration for T. grandis. Biomass was negatively correlated with lignin and L/N ratio for S. robusta and L, WSC, L/N and C/N ratio for T. grandis （P 〈 0.01）. Nutrient use efficiency （NUE） and nutrient accumulation index （NAI） of S. robusta was higher than for T. grandis. The retranslocation of bioelements from senescent leaves ranked as P 〉 N 〉 K. Annual N, P and K input to soil through litterfall differed significantly between the two species in the following order： N〉K^P. S. robusta was superior in terms of K and P return and T. grandis was superior in terms of N return. The two tree species showed a similar patterns of nutrient release （K 〉 P 〉 N） during decomposition of their leaf litter.Nutrients of N, K and P were the primary limiting nutrients returned to soil through litterfall with important roles in soil fertility and forest productivity.

Decomposition and nutrient release patterns of Phyllostachys bambusoides and Arundinaria racemosa, India

We investigated decomposition and nutrient release patterns of leaf and sheath litter of two important highland bamboo species （viz. Phyllostachys bambusoides Sieb. （Zucc.） and Arundinaria racemosa Munro） by using a litter bag technique. Our objective was to improve understanding of the addition of organic matter and nutrients to soil from the litter of two abundant highland bamboo species, species that support the local population of the region in many ways. N concentration and N/P ratio were significantly higher （p〈0.01） in leaf litter of P bambusoides. Significantly, larger values of lignin concentration, C/N ratio, and lignin/N ratio were found in the sheath litter ofA racemosa. Weight loss of both leaf and sheath litter was strongly positively correlated with N and N/P ratio, and significantly negatively correlated 6o〈0.01） with C/N ratio. Lignin/N had a negative correlation with decay rate. In both species, only lignin concentration of the litter showed strong positive correlation with N release. Litter decomposition and N release patterns were similar for the two bamboo species, whereas, P release rate from leaf litter was higher in P bambusoides and differed significantly between sheath and leaf litter for both species. The complex pattern of nutrient release through mineralization and immobilization during litter decomposition ensures nutrient availability in both managed and natural bamboo stands subjected to anthropogenic disturbances.

Charmonium Spectrum and Their Transitions in Relativistic Quark Models

Using the phenomenological relativistic harmonic model （RHM） for quarks, we have obtained the masses of S wave charmonium states. The full Hamiltonian used in the investigation has Lorentz scalar plus vector confinement potential, along with the confined one gluon exchange potential （COGEP）. A good agreement with the experimental masses for the ground state and the radially excited states is obtained for both the triplet and singlet S wave mesons. The calculated charge radii, meson decay constants, leptonic decay width, two photon decay width, and the radiative M1 decay width are in good agreement with the experimental results.

Analysis of sand particles’ lift-off and incident velocities in wind-blown sand flux

In the research of windblown sand movement,the lift-off and incident velocities of saltating sand particles play a significant role in bridging the spatial and temporal scales from single sand particle＇s motion to windblown sand flux.In this paper,we achieved wind tunnel measurements of the movement of sand particles near sand bed through improving the wind tunnel experimental scheme of paticle image velocimetry（PIV） and data processing method.And then the influence of observation height on the probability distributions of lift-off and incident velocities of sand particles was analyzed.The results demonstrate that the observation height has no obvious influence on the distribution pattern of the lift-off and incident velocities of sand particles,i.e.,the probability distribution of horizontal and vertical velocities of lift-off and incident sand particles follow a Gaussian distribution and a negative exponential distribution,respectively.However,it influences the center of the Gaussian distribution,the decay constant and the amplitude of the negative exponential distribution.

Quark-Number Susceptibility at Finite Chemical Potential and Zero Temperature

We give a direct method for calculating the quark-number susceptibility at finite chemical potential and zero temperature. In this approach the quark-number susceptibility is totally determined by G[μ]（p） （the dressed quark propagator at finite chemical potential μ）. By applying the general result in our previous study [Phys. Rev. C 71 （2005） 015205, 034901, 73 （2006） 016004 ] G[μ]（p） is calculated from the model quark propagator proposed by Pagels and Stokar [Phys. Rev. D 20 （1979） 2947]. The full analytic expression of the quark-number susceptibility at finite μ and zero T is obtained.

A Comparative Study of f_B within QCD Sum Rules with Two Typical Correlators up to Next-to-Leading Order

The B-meson decay constant fB is an important component for studying the B-meson decays, which can be studied through QCD sum rules. We make a detailed discussion on f B from two sum rules up to next-to- leading order, i.e. sum rules I and II, which are derived from the conventional correlator and the correlator with chiral currents respectively. It is found that these two sum rules are consistent with each other. The sum rules H involves less non-perturbative condensates as that of sum rules I, and in principle, it can be more accurate if we know the dimensionfour gluon condensate well. It is found that fB decreases with the increment of mb, and to compare with the Belle experimental data on fB, both sum rules I and H prefer smaller pole b-quark mass, mb= 4.68 ± 0.07 GeV. By varying all the input parameters within their reasonable regions and by adding all the uncertainties in quadrature, we obtain fB=172-25^＋23 MeV for sum rules I and fB =214-34^26 MeV for sum rules П.

A novel non-iterative shape method for estimating the decay time constant of the finger photoplethysmographic pulse

The photoplethysmogram(PPG) of a pulse wave,similar in appearance to the arterial blood pressure(ABP) waveform,contains rich information about the cardiovascular system.The decay time constant RC,equal to the product of peripheral resistance R and total arterial compliance C,is a meaningful cardiovascular model parameter in vascular assessment.Using or ameliorating the existing ABP methods does not achieve a satisfactory estimation of RC from the PPG volume pulse(VRC).Thus,a novel non-iterative shape method(NSM) of evaluating VRC is introduced in this paper.The mathematic expression between a novel,readily available morphological parameter called the area difference ratio(ADR) and VRC was established.As it was difficult to calculate VRC from the complicated expression analytically,we recommend estimating it using a piecewise linear interpolation criterion.Also,since the effect of the PPG magnitude is eliminated in the calculation of ADR,precaliberation or normalization is dispensable in the NSM.Results of human experiments indicated that the NSM was computationally efficient,and the simulation experiments confirmed that the NSM was theoretically available for ABP.

Exotic vector charmonium and its leptonic decay width

We propose a novel type of interpolating field operator, which manifests the hybrid-like configuration that the charm quark-antiquark pair recoils against gluonie degrees of freedom. A heavy vector charmonium-like state with a mass of 4.33（2） GeV is disentangled from the conventional charmonium states in the quenched approximation. This state has affinity for the hybrid-like operators but couples less to the relevant quark bilinear operator. We also try to extract its leptonic decay constant and give a tentative upper limit that it is less than one tenth of that of J/ψ, which corresponds to a leptonic decay width about dozens of eV. The connection of this state with X（4260） is also discussed.

Charm physics with overlap fermions on 2+1-flavor domain wall fermion configurations

Decay constants of pseudoscalar mesons D,D_(s),η_(c) and vector mesons D^(*),D_(s)^(*),J/ψ are determined from the N_(f)=2+1 lattice QCD at a lattice spacing a~0.08 fm.For vector mesons,the decay constants defined by tensor currents are given in the MS scheme at 2 GeV.The calculation is performed on domain wall fermion configurations generated by the RBC-UKQCD collaborations and the overlap fermion action is used for the valence quarks.Comparing the current results with our previous results at a coarser lattice spacing a ~0.11 fm provides a better understanding of the discretization error.We obtain f_(D_(s)^(*))^(T)(MS,2 GeV)/f_(D_(s)^(*))=0.909(18)with a better precision than our previous result.Combining our f_(D_(s)^(*))=277(11)MeV with the total width of D_(s)^(*) determined in a recent study gives a branching fraction 4.26(52)×10^(-5) for D_(s)^(*) leptonic decay.

Alpha Decay Half-Lives of Some Nuclei from Ground State to Ground State with Yukawa Proximity Potential

We study the half-lives of some nuclei via the alpha-decay process from ground state to ground state. To go through the problem, we have considered a potential model with Yukawa proximity potential and have thereby calculated the half-lives. The comparison with the existing data is motivating.