Asymmetric behavior of the B$(E2 \uparrow; 0^+ \rightarrow 2^+)$ values   in $^{104-130}$Sn and Generalized Seniority
  We present freshly evaluated B$(E2\uparrow;0^+\rightarrow2^+)$ values across the even-even Sn-isotopes which confirm the presence of an asymmetric behavior as well as a dip in the middle of the full valence space. We explain these features by using the concept of generalized seniority. The dip in the B$(E2)$ values near $^{116}$Sn is understood in terms of a change in the dominant orbits before and after the mid shell, which also explains the presence of asymmetric peaks in the B$(E2)$ values. This approach helps in deciding the most active valence spaces for a given set of isotopes, and single out the most useful truncation scheme for Large Scale Shell Model (LSSM) calculations. The LSSM calculations so guided by generalized seniority are also able to reproduce the experimental data on B$(E2)\uparrow$ values quite well. 
Bhoomika Maheshwari, Ashok Kumar Jain, and Balraj Singh
nucl-th