MI and El transition decay widths in Qq and QQ systems ( q = u,d,s; Q = c, b ) are calculated in the nonrelativistic quark model with the Cornell potential. The relativistic and recoil corrections are taken into account. Results are compared with their experimental values. PACS number(s1: 13.40.Hq, 12.40.Qq, 14.40.G~

The E 1 transition decay widths for the decays D: -D * + y, Dl +D + y, and D, +D* + y are calculated in the nonrelativistic quark model with recoil and relativistic corrections. PACS number(s): 13.40.Hq, 12.39.Hg, 12.39.Jh, 14.40.Lb In heavy quark effective field theory (HQEFT) [I], the heavy quark spin is decoupled. As a consequence of this, we have spin multiplets such as [D (OP),D*( 1-11, [ 0~( 2 + ) ,~, ( 1 + ) ] , and [ D~(~+ ) , D~( o + ) ] . The structure of the angular part of the wave function of the heavy meson [2] has some interesting consequences regarding the radiative decay [2,3] of P-wave D mesons.In particular, J = 1 mesons D and D : both contain the spin-singlet component x:. This has the consequence that D l (2420 ) and D 7 can decay to D ( 'so ) with the E 1 transition [2]. Thus the heavy quark spin symmetry predicts, for D l -D * --t y and D l -D + y , and,forDf + D * + y andD:-tD+y decays,

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Using Thomas-Fermi-Dirac equation within the exchange-correlation scheme and a Z-dependent trial solution, the ground state binding energy for neutral, positively, and negatively charged atoms are calculated. Comparing to the results obtained in earlier works, the values of the binding energy estimated here for both light and heavy atoms agree nicely with the Hartree-Fock values. We have also calculated the radial expectation values and diamagnetic susceptibilities for some neutral and single ionised atoms. Our results are compared with the available theoretical and experimental findings.