Charm meson couplings in hard-wall Holographic QCD

The four-flavor hard-wall holographic QCD is studied to evaluate the couplings of $(D^{_{-(*-)}}, \bar{D}^{_0}, a_1^{_-})$, $(D^{_{-(*-)}}, \bar{D}^{_0}, b_1^{_-})$, $(D_{s}^{_{-(*-)}},\bar{D}^{_0}, K_{1A}^{_-})$, $(D_s^{_{-(*-)}}, \bar{D}^{_0}, K_{1B}^{_{-(*-)}})$, $(D_s^{_{+(*+)}}, D^{_+}, K_{1A}^{_0})$, $(D_s^{_{+(*+)}}, D^{_+}, K_{1B}^{_0})$, $(D^{_{-(*-)}}, \bar{D}^{_{0(*0)}}, \rho^{_-})$, $(D_s^{_{-(*-)}}, \bar{D}^{_{0(*0)}}, K^{_{*-}})$, $(D^{_{0(*0)}}, \bar{D}^{_{0(*0)}}, \psi)$, $(D_1^{_-}, \bar{D}_1^{_0}, \pi^{_-})$, $(D_{s1}^{_-}, \bar{D}_1^{_0}, K^{_{-}})$, $(D_1^{_0}, \bar{D}_1^{_0}, \eta_c)$, $(\psi, D^{_{0(*0)}}, D^{_+}, \pi^{_-})$, $(\psi, D^{_{0(*0)}}, \bar{D}^{_0}, \pi^{_0})$, $(\psi, D_{s}^{_{+(*+)}}, D^{_-}, K^{_0})$, $(\psi, D^{_{0(*0)}}, D^{_+}, a_1^{_-})$, $(\psi, D^{_{0(*0)}}, D^{_+}, b_1^{_-})$, $(\psi, D_s^{_{+(*+)}}, D^{_-}, K_{1B}^{_0})$ and $(\psi, D_s^{_{+(*+)}}, D^{_-}, K_{1B}^{_0})$ vertices. Moreover, the values of the masses of $D^{_{0(*0)}}$, $D_s^{_{-(*-)}}$, $\omega$, $\psi$, $D_1^{_0}$, $D_1^{_{-}}$, $K^0$, $\eta_{c}$, $D_{s1}^{_-}$ and $\chi_{_{c1}}$ as well as the decay constant of $\pi^-$, $D^{_{-(*-)}}$, $K^-$, $\rho^-$, $D_1^{_-}$ , $a_1^-$ and $D_s^{_{-(*-)}}$ are estimated in this study. A comparison is also made between our results and the experimental values of the masses and decay constants. Our results for strong couplings are also compared with the 3PSR and LCSR predictions

Cylindrical Solutions in Modified f(T) Gravity

We investigate static cylindrically symmetric vacuum solutions in Weyl coordinates in the framework of f(T) theories of gravity, where T is the torsion scalar. The set of modified Einstein equations is presented and the fourth coming equations are established. Specific physical expressions are assumed for the algebraic function f(T) and solutions are obtained. Moreover, general solution is obtained with finite values of u(r) on the axis r = 0, and this leads to a constant torsion scalar. Also, cosmological constant is introduced and its relation to Linet-Tian solution in GR is commented.Comment: 13 pages; Accepted for publication in International Journal of Modern Physics D (IJMPD

Population dynamics of Sind Sardine, Sardinella sindensis, in coastal waters of Qeshm Island

Sardinella sindensis is economically the most important small pelagic fish species in the coastal area of Qeshm Island. Population dynamics of Sind sardinella from Qeshm Island coastal waters, during April 2005 to March 2006 were studied. The asymptotic length (Lx) and growth coefficient (K) were estimated at 178mm and 1.11yr ^(-1), respectively. The minimum and maximum T.L was recorded at 42 and 172mm respectively. The value of t0 was calculated at -0.17, and Tmax was estimated at 2.7 year. The Von Bertalanffy growth equation was obtained at L_(t) = 178^(1-exp(-1.1 l(t-(-0.17))) for this species. Total mortality (Z) rate was estimated to be 3.48yr ^(-1) (r ^(2) = 0.88) on length-converted catch curve method. The rates of natural mortality (M) based on Pauly's empirical equation, fishing mortality (F) and exploitation ratio were estimated at 1.13yr ^(-1), 2.35yr ^(-1) and 0.67, respectively. Four cohorts were distinguished annually based on Bhattacharya's method with mean length of 56, 89, 107 and 141mm. Maximum recruitment was in September at 18.62 percent. The length-weight relationship was determined as W= 0.000005 L ^(3.1399)

Numerical solution of linear time delay systems using Chebyshev-tau spectral method

In this paper, a hybrid method based on method of steps and a Chebyshev-tau spectral method for solving linear time delay systems of differential equations is proposed. The method first converts the time delay system to a system of ordinary dierential equations by the method of steps and then employs Chebyshev polynomials to construct an approx- imate solution for the system. In fact, the solution of the system is expanded in terms of orthogonal Chebyshev polynomials which reduces the solution of the system to the solution of a system of algebraic equations. Also, we transform the coefficient matrix of the algebraic system to a block quasi upper triangular matrix and the latter system can be solved more efficiently than the first one. Furthermore, using orthogonal Chebyshev polynomials enables us to apply fast Fourier transform for calculating matrix-vector multiplications which makes the proposed method to be more efficient. Consistency, stability and convergence analysis of the method are provided. Numerous numerical examples are given to demonstrate efficiency and accuracy of the method. Comparisons are made with available literature