Optimized generalized monogamy relations and upper bounds for N-qubit systems

We present optimized generalized monogamy relations and upper bounds derived from concurrence and concurrence of assistance. We first establish a tighter general upper bound of the αth ( ) power of concurrence for N-qubit states. Then for N-qubit systems , the optimized monogamy relations and upper bounds satisfied by the αth ( ) power of concurrence of N-qubit pure states under the partition AB and , as well as under the partition ABC1 and are established, which give rise to restrictions on the entanglement distribution and trade offs among the subsystems. Moreover, the utilization of the W-class states demonstrates that our results are tighter compared with the existing results. Similar results are also obtained for negativity.