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تسجيل مستخدم جديدParticle number conserving approach to correlations
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In the present work the so-called Higher Tamm-Dancoff Apporximation method is presented for the generalized case of isovector and isoscalar residual interactions treated simultaneously. The role of different particle-hole excitations and of proton-neutron pairing correlations in the ground state of the self-conjugate 64Ge nucleus is discussed.
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We calculate the isospin-mixing parameter for several Tz=-1, Tz=0 and Tz=1 nuclei from Mg to Sn in the particle-number conserving Higher Tamm-Dancoff approach taking into account the pairing correlations. In particular we investigate the role of the
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Particle number fluctuations and correlations in nucleus-nucleus collisions at SPS and RHIC energies are studied within the statistical hadron-resonance gas model in different statistical ensembles and in the Hadron-String-Dynamics (HSD) transport ap
proach. Event-by-event fluctuations of the proton to pion and kaon to proton number ratios are calculated in the HSD model for the samples of most central collision events and compared with the available experimental data. The role of the experimental acceptance and centrality selection is discussed.
Experimentally observed ground state band based on the $1/2^{-}[521]$ Nilsson state and the first exited band based on the $7/2^{-}[514]$ Nilsson state in the odd-$Z$ nucleus $^{255}$Lr are studied by the cranked shell model (CSM) with the paring cor
relations treated by the particle-number-conserving (PNC) method. This is the first time the detailed theoretical investigations being performed on these rotational bands. Both the experimental kinematic and dynamic moment of inertia ($mathcal{J}^{(1)}$ and $mathcal{J}^{(2)}$) versus rotational frequency are reproduced quite well by the PNC-CSM calculations. By comparing the theoretical kinematic moment of inertia $mathcal{J}^{(1)}$ with the experimental ones extracted from different spin assignments, the spin $17/2^{-}rightarrow13/2^{-}$ is assigned to the lowest-lying $196.6(5)$ keV transition of the $1/2^{-}[521]$ band, and $15/2^{-}rightarrow11/2^{-}$ to the $189(1)$ keV transition of the $7/2^{-}[514]$ band, respectively. The proton $N=7$ major shell is included in the calculations. The intruder of the high$-j$ low$-Omega$ orbitals $1j_{15/2}$ $ (1/2^{-}[770])$ at the high spin leads to the band-crossing at $hbaromegaapprox0.20$ ($hbaromegaapprox0.25$) MeV for the $7/2^{-}[514]$ $alpha=-1/2$ ($alpha=+1/2$) band, and at $hbaromegaapprox0.175$ MeV for the $1/2^{-}[521]$ $alpha=-1/2$ band, respectively. Further investigations show that the band-crossing frequencies are quadrupole deformation dependent.
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