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1. Photoassociation of ${}^{84}\mathrm{Sr}$ $n{}^1{D}_2$ ultralong-range Rydberg dimers

   https://doi.org/10.1103/ppv2-mlfd  

   Wang, C; Li, A; Kanungo, S K; Killian, T C; Dunning, F B; Yoshida, S (May 2026, Physical Review A)

   Measurements of the production of $5snd{}^1{D}_2–5s^2{}^1{S}_0$ ultralong-range Rydberg dimers through photoassocation in an ultracold ${}^{84}\mathrm{Sr}$ atomic gas are reported. The molecular potential associated with the Rydberg $D$ state is anisotropic and the molecular states are characterized by the vibrational quantum number $\nu$ and the total angular momentum $\vec{K}=\vec{L}+\vec{N}$ , where $\vec{L}$ and $\vec{N}$ are the electronic orbital angular momentum and rotational angular momentum, respectively. The measured molecular binding energies agree reasonably well with theoretical predictions. Additionally, the electron-atom scattering leads to broader line shapes in the photoassociation spectrum than might be expected simply from the angular momentum of the initial colliding cold-atom pairs. 

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2. Precision measurement of lifetime and branching ratios of the $4f^{13}5d6s^1{[5/2]}_{5/2}$ state in ${\mathrm{Yb}}^{+}$ ions

   https://doi.org/10.1103/mwwc-kng1  

   Duraisamy_Suganthi, Midhuna; So, Visal; Menon, Abhishek; Tomaras, George; Zhuravel, Roman; Pagano, Guido (December 2025, Physical Review Research)

   We report spectroscopic and time-resolved experimental observations to characterize the $\left[\mathrm{Xe}\right]4f^{13}\left({}^{2}F_{5/2}^o\right)5d6s\left({}^{1}D\right){}^1{[5/2]}_{5/2}^o$ state in ${}^{172}\mathrm{Yb}^{+}$  ions. We access this state from the metastable $4f^{14}5d\left({}^{2}D_{3/2,5/2}\right)$ manifold and observe an unexpectedly long lifetime of $\tau =37.9\left(9\right)\mu \mathrm{s}$  that allows visible Rabi oscillations and resolved-sideband spectroscopy. Using a combination of coherent population dynamics, high-fidelity detection and heralded state preparation, and optical pumping methods, we measure the branching ratios to the ${}^{2}D_{3/2}, {}^{2}D_{5/2}$ , and ${}^{2}S_{1/2}$ states to be $0.359\left(2\right)$ , 0.639(2), and $0.0023\left(16\right)$ , respectively. The branching ratio to the $4f^{13}6s^2\left({{}^{2}F}_{7/2}\right)$ is compatible with zero within our experimental resolution. We also report measurements of Landé $g$ -factor of the ${}^1{[5/2]}_{5/2}^o$ state. Further, the branching ratio of the ${}^{2}D_{5/2}$ to ${}^{2}S_{1/2}$ decay in ${}^{172}\mathrm{Yb}^{+}$  was measured to be 0.188(3), improving its relative uncertainty by an order of magnitude. Our measurements provide experimental benchmarks for better understanding the atomic structure of ${\mathrm{Yb}}^{+}$  ions, which still lacks accurate numerical descriptions, and the use of high-lying excited states for partial detection and qubit manipulation in the architecture. 

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3. Spin-Forbidden Excitations in the Magneto-optical Spectra of ${\mathrm{CrI}}_3$ Tuned by Covalency

   https://doi.org/10.1103/4km4-4rvn  

   Occhialini, Connor A; Nessi, Luca; Martins, Luiz_G P; Demir, Ahmet Kemal; Song, Qian; Hasse, Vicky; Shekhar, Chandra; Felser, Claudia; Watanabe, Kenji; Taniguchi, Takashi; et al (July 2025, Physical Review X)

   Spin-forbidden ( $\mathrm{\Delta }S\ne 0$ ) multiplet excitations and their coupling to magnetic properties are of increasing importance for magneto-optical studies of correlated materials. Nonetheless, the mechanisms for optically brightening these transitions and their generality remain poorly understood. Here, we report magnetic circular dichroism (MCD) spectroscopy on the van der Waals ferromagnet (FM) ${\mathrm{CrI}}_3$ . Previously unreported spin-forbidden ( $\mathrm{\Delta }S=1$ ) ${{}^{4}A}_{2\mathrm{g}}\to {{}^{2}E}_{\mathrm{g}}/{{}^{2}T}_{1\mathrm{g}}$ ${\mathrm{Cr}}^{3+}$ $dd$ excitations are observed near the ligand-to-metal charge-transfer excitation threshold. The assignment of these excitations and their ${\mathrm{Cr}}^{3+}$ multiplet character is established through complementary Cr $L_3$ -edge resonant inelastic x-ray scattering measurements along with charge-transfer multiplet calculations and chemical trends in the chromium trihalide series ( $\mathrm{Cr}{X}_3$ , $X=$ Cl, Br, I). We utilize the high sensitivity of MCD spectroscopy to study the thickness-dependent optical response. The spin-forbidden excitations remain robust down to the monolayer limit, and we observe a significant magnetic-field dependence of the MCD spectrum across the antiferromagnetic-to-FM transition in few-layer samples. We preliminarily attribute this behavior to changes in the metal-ligand covalency with magnetic state. Our results clarify the magneto-optical response of ${\mathrm{CrI}}_3$ and identify covalency as a central mechanism for the brightening and field tunability of spin-forbidden multiplet excitations. 

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4. Asymptotic normalization coefficients for $\alpha +{}^{12}\mathrm{C}$ synthesis and the $S$ factor for ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ radiative capture

   https://doi.org/10.1103/PhysRevC.110.055803  

   Mukhamedzhanov, A M; deBoer, R J; Irgaziev, B F; Blokhintsev, L D; Kadyrov, A S; Savin, D A (November 2024, Physical Review C)

   : The ${}^{12}\mathrm{C}(\alpha ,\gamma ){}^{16}\mathrm{O}$ reaction, determining the survival of carbon in red giants, is of interest for nuclear reaction theory and nuclear astrophysics. A specific feature of the ${}^{16}\mathrm{O}$ nuclear structure is the presence of two subthreshold bound states, (6.92 MeV, $2^{+}$ ) and (7.12 MeV, $1^{-}$ ), that dominate the behavior of the low-energy $S$ factor. The strength of these subthreshold states is determined by their asymptotic normalization coefficients (ANCs), which need to be known with high accuracy. : The objective of this research is to examine how the subthreshold and ground-state ANCs impact the low-energy $S$ factor, especially at the key astrophysical energy of $300\mathrm{keV}$ . The $S$ factors are calculated within the framework of the $R$ -matrix method using the code. Our total $S$ factor takes into account the $E1$ and $E2$ transitions to the ground state of ${}^{16}\mathrm{O}$ including the interference of the subthreshold and higher resonances, which also interfere with the corresponding direct captures, and cascade radiative captures to the ground state of ${}^{16}\mathrm{O}$ through four subthreshold states: $0_2^{+},3^{-},2^{+}$ , and $1^{-}$ . To evaluate the impact of subthreshold ANCs on the low-energy $S$ factor, we employ two sets of the ANCs. The first selection, which offers higher ANC values, is attained through the extrapolation process [Blokhintsev , ]. The set with low ANC values was employed by deBoer []. A detailed comparison of the $S$ factors at the most effective astrophysical energy of 300 keV is provided, along with an investigation into how the ground-state ANC affects this $S$ factor. : The contribution to the total $E1$ and $E2S$ factors from the corresponding subthreshold resonances at $300\mathrm{keV}$ are $(71–74)\%$ and $(102–103)\%$ , respectively. The correlation of the uncertainties of the subthreshold ANCs with the $E1$ and $E2S\left(300\mathrm{keV}\right)$ factors is found. The $E1$ transition of the subthreshold resonance $1^{-}$ does not depend on the ground-state ANC but interferes constructively with a broad $(9.585\mathrm{MeV};1^{-})$ resonance giving (for the present subthreshold ANC) an additional $26\%$ contribution to the total $E1S\left(300\mathrm{keV}\right)$ factor. Interference of the $E2$ transition through the subthreshold resonance $2^{+}$ with direct capture is almost negligible for small ground-state ANC of $58{\mathrm{fm}}^{-1/2}$ . However, its interference with direct capture for higher ground-state ANC of $337{\mathrm{fm}}^{-1/2}$ is significant and destructive, contributing $-27\%$ . The low-energy $S_{E2}\left(300\mathrm{keV}\right)$ factor experiences a smaller increase when both subthfreshold and the ground-state ANCs rise together due to their anticorrelation, compared to when only the subthreshold ANCs increase. Published by the American Physical Society2024 

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5. First Determination of the Spin-Parity of ${\mathrm{\Xi }}_c(3055{)}^{+,0}$ Baryons

   https://doi.org/10.1103/PhysRevLett.134.081901  

   Aaij, R; Abdelmotteleb, A_S W; Abellan_Beteta, C; Abudinén, F; Ackernley, T; Adefisoye, A A; Adeva, B; Adinolfi, M; Adlarson, P; Agapopoulou, C; et al (February 2025, Physical Review Letters)

   The ${\mathrm{\Xi }}_b^{0(-)}\to {\mathrm{\Xi }}_c\left(3055{)}^{+\left(0\right)}\right(\to D^{+\left(0\right)}\mathrm{\Lambda }){\pi }^{-}$ decay chains are observed, and the spin-parity of ${\mathrm{\Xi }}_c(3055{)}^{+\left(0\right)}$ baryons is determined for the first time. The measurement is performed using proton-proton collision data at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$ , corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$ , recorded by the LHCb experiment between 2016 and 2018. The spin-parity of the ${\mathrm{\Xi }}_c(3055{)}^{+\left(0\right)}$ baryons is determined to be $3/2^{+}$ with a significance of more than $6.5\sigma$ ( $3.5\sigma$ ) compared to all other tested hypotheses. The up-down asymmetries of the ${\mathrm{\Xi }}_b^{0(-)}\to {\mathrm{\Xi }}_c(3055{)}^{+\left(0\right)}{\pi }^{-}$ transitions are measured to be $-0.92\pm 0.10\pm 0.05$ ( $-0.92\pm 0.16\pm 0.22$ ), consistent with maximal parity violation, where the first uncertainty is statistical and the second is systematic. These results support the hypothesis that the ${\mathrm{\Xi }}_c(3055{)}^{+\left(0\right)}$ baryons correspond to the first $D$ -wave $\lambda$ -mode excitation of the ${\mathrm{\Xi }}_c$ flavor triplet. © 2025 CERN, for the LHCb Collaboration2025CERN 

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