TABLE III: Lorentzian-fit parameters for the ISGMR strength distributions in the Sn isotopes, as extracted from MDA. The quoted EWSR values are from the fitted Lorentzians. The results from TAMU work (from Gaussian fits), where available, are provided for comparison [19, 21]. a Only statistical uncertainties are included; systematic errors, mostly from DWBA calculations, are ∼ 15%. The primary focus of this work has been on the ISGMR because of its direct connection with the nuclear incompressibility. The excitation energy of the ISGMR is expressed in the scaling model [70] as: where m is the nucleon mass, < r 2 > the ground-state mean-square radius, and K$_{A}$ , the incompressibility of the nucleus. The moment ratios, m 1 /m 0 , for the ISGMR strengths in the Sn isotopes are shown in Fig. 13 and compared with recent theoretical results from Col` o et al. (non-relativistic) [65, 66] and Piekarewicz (relativistic) [67]. The calculations overestimate the experimental ISGMR energies significantly (by almost 1 MeV in case of the higher-A isotopes!). This difference is very surprising since the interactions used in these calculations are those that very closely reproduce the ISGMR energies in $^{208}$Pb and $^{90}$Zr. Indeed, this disagreement leaves open a puzzling question: Why are the tin isotopes so soft [67]? Are there any nuclear structure effects that need to be taken into account to describe the ISGMR energies in the Sn isotopes? Or, more provocatively, do the ISGMR energies depend on something more 17 E$_{ISGMR}$ = ¯ h √ K$_{A}$ m < r $^{2}$> (7) Target E$_{ISGMR}$ (MeV) Γ (MeV) EWSR a Reference $^{112}$Sn 16 . 1 ± 0 . 1 4 . 0 ± 0 . 4 0 . 92 ± 0 . 04 This work 15 . 67 +0 . 11 − 0 11 5 . 18 +0 . 40 − 0 04 1 . 10 +0 . 15 − 0 12 TAMU $^{114}$Sn 15 . 9 ± 0 . 1 4 . 1 ± 0 . 4 1 . 04 ± 0 . 06 This work $^{116}$Sn 15 . 8 ± 0 . 1 4 . 1 ± 0 . 3 0 . 99 ± 0 . 05 This work $^{118}$Sn 15 . 6 ± 0 . 1 4 . 3 ± 0 . 4 0 . 95 ± 0 . 05 This work $^{120}$Sn 15 . 4 ± 0 . 2 4 . 9 ± 0 . 5 1 . 08 ± 0 . 07 This work $^{122}$Sn 15 . 0 ± 0 . 2 4 . 4 ± 0 . 4 1 . 06 ± 0 . 05 This work $^{124}$Sn 14 . 8 ± 0 . 2 4 . 5 ± 0 . 5 1 . 05 ± 0 . 06 This work 15 . 34 +0 . 13 − 0 13 5 . 00 +0 . 13 − 0 53 1 . 06 +0 . 10 − 0 20 TAMU