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1. Study of light-meson resonances decaying to $K_{\mathrm{S}}^{0}K\pi$ in the $B\to \left(K_{\mathrm{S}}^{0}K\pi \right)K$ channels

   https://doi.org/10.1103/PhysRevD.111.092009  

   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 (May 2025, Physical Review D)

   A study is presented of $B^{+}\to K_{\mathrm{S}}^0{K}^{-}{\pi }^{+}{K}^{+}$ and $B^{+}\to K_{\mathrm{S}}^0{K}^{+}{\pi }^{-}{K}^{+}$ decays based on the analysis of proton-proton collision data collected with the LHCb detector at center-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of $9{\mathrm{fb}}^{-1}$ . The $K_{\mathrm{S}}^{0}K\pi$ invariant-mass distributions of both $B^{+}$ decay modes show, in the $m\left(K_{\mathrm{S}}^{0}K\pi \right)<1.85\mathrm{GeV}$ mass region, large activity which is resolved using an amplitude analysis. A simple model, where $J^{PC}$ amplitudes are described by multiple Breit-Wigner functions with appropriate angular distributions, provides a good description of the experimental data. In this approach a complex mixture of $J^{PC}=0^{-+}$ , $1^{++}$ and $1^{+-}$ amplitudes is observed that is dominated by $\eta \left(1405\right)$ , $\eta \left(1470\right)$ , $\eta \left(1760\right)$ , $f_1\left(1285\right)$ , $f_1\left(1420\right)$ and $h_1\left(1405\right)$ resonances. The $K_{\mathrm{S}}^{0}K\pi$ Dalitz plots are dominated by asymmetric crossing $K^{*}\overline{K}$ bands which are different for the two $B^{+}$ decay modes. This is due to a different interference pattern between the $1^{++}$ and $1^{+-}$ amplitudes in the two channels. Branching fractions are measured for each resonant contribution. © 2025 CERN, for the LHCb Collaboration2025CERN 

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2. Fractionalization of coset non-invertible symmetry and exotic Hall conductance

   https://doi.org/10.21468/SciPostPhys.17.3.095  

   Hsin, Po-Shen; Kobayashi, Ryohei; Zhang, Carolyn (January 2024, SciPost Physics)

   We investigate fractionalization of non-invertible symmetry in (2+1)D topological orders. We focus on coset non-invertible symmetries obtained by gauging non-normal subgroups of invertible0 $0$ -form symmetries. These symmetries can arise as global symmetries in quantum spin liquids, given by the quotient of the projective symmetry group by a non-normal subgroup as invariant gauge group. We point out that such coset non-invertible symmetries in topological orders can exhibit symmetry fractionalization: each anyon can carry a “fractional charge” under the coset non-invertible symmetry given by a gauge invariant superposition of fractional quantum numbers. We present various examples using field theories and quantum double lattice models, such as fractional quantum Hall systems with charge conjugation symmetry gauged and finite group gauge theory from gauging a non-normal subgroup. They include symmetry enrichedS_3 $S_3$ andO(2) $O\left(2\right)$ gauge theories. We show that such systems have a fractionalized continuous non-invertible coset symmetry and a well-defined electric Hall conductance. The coset symmetry enforces a gapless edge state if the boundary preserves the continuous non-invertible symmetry. We propose a general approach for constructing coset symmetry defects using a “sandwich” construction: non-invertible symmetry defects can generally be constructed from an invertible defect sandwiched by condensation defects. The anomaly free condition for finite coset symmetry is also identified. 

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3. Search for Lepton-Flavor-Violating Decay Modes $B^0\to K_S^0{\tau }^{\pm }{\ell }^{\mp }$ with Hadronic $B$ Tagging at Belle and Belle II

   https://doi.org/10.1103/yzvh-v3hm  

   Adachi, I; Adamczyk, K; Aggarwal, L; Ahmed, H; Aihara, H; Akopov, N; Alhakami, M; Aloisio, A; Althubiti, N; Ky, N Anh; et al (July 2025, Physical Review Letters)

   We present the first search for the lepton-flavor-violating decay modes $B^0\to K_S^0{\tau }^{\pm }{\ell }^{\mp }$ ( $\ell =\mu ,e$ ) using the 711 and $365{\mathrm{fb}}^{-1}$ data samples recorded by the Belle and Belle II detectors, respectively. We use a hadronic $B$ -tagging technique to fully reconstruct a $B$ meson and search for signal decays in the system recoiling against the tagged meson, considering $\tau$ decays to either light leptons, one charged hadron, or one charged hadron and a neutral pion. We find no evidence for $B^0\to K_S^0{\tau }^{\pm }{\ell }^{\mp }$ decays and set 90% confidence level upper limits on the branching fractions in the range of $[0.8,3.6]\times {10}^{-5}$ . 

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4. Axionlike particles and sterile neutrinos solve the $B\to K\nu \overline{\nu }$ and $B\to \pi K$ puzzles

   https://doi.org/10.1103/gd5l-gjrz  

   Bhattacharya, Bhubanjyoti; Datta, Alakabha; Kumar, Girish; Marfatia, Danny (August 2026, Physical Review D)

   The recent measurement of the branching ratio of $B^{+}\to K^{+}+\mathrm{inv}$ (where “inv” denotes invisible states) by the Belle II Collaboration is enhanced relative to the standard model expectation by $2.7\sigma$ . An older puzzle persists in measurements of the branching ratios and $CP$ asymmetries of $B\to \pi K$ decays. We address these two anomalies in flavor-changing neutral current $B$ decays, with a short-lived axionlike particle (ALP) with mass close to that of the ${\pi }^0$ . In the model with the minimum number of new couplings, the ALP has couplings to the photon, top quark and a heavy sterile neutrino. The ALP contributes to the $B\to {\pi }^{0}K$ decays by mixing with the ${\pi }^0$ . It contributes to $B^{+}\to K^{+}+\mathrm{inv}$ by its off-shell coupling to sterile neutrino pairs. The model can explain the excess in the total rate, but not the observed distribution of signal events. We make predictions for all $B\to K^{(*)}+\mathrm{inv}$ modes and for the rare kaon decays, $K^{+}\to {\pi }^{+}+\mathrm{inv}$ and $K_L\to {\pi }^0+\mathrm{inv}$ . We find an appreciable contribution to the magnetic moment of the muon, and negligible contributions to the magnetic moment of the electron and $b\to s{e}^{+}{e}^{-}$ . 

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5. Photoproduction of $K^{+}{K}^{-}$ Pairs in Ultraperipheral Collisions

   https://doi.org/10.1103/PhysRevLett.132.222303  

   Acharya, S; Adamová, D; Aglieri_Rinella, G; Agnello, M; Agrawal, N; Ahammed, Z; Ahmad, S; Ahn, S U; Ahuja, I; Akindinov, A; et al (May 2024, Physical Review Letters)

   $K^{+}{K}^{-}$ pairs may be produced in photonuclear collisions, either from the decays of photoproduced $\varphi \left(1020\right)$ mesons or directly as nonresonant $K^{+}{K}^{-}$ pairs. Measurements of $K^{+}{K}^{-}$ photoproduction probe the couplings between the $\varphi \left(1020\right)$ and charged kaons with photons and nuclear targets. The kaon-proton scattering occurs at energies far above those available elsewhere. We present the first measurement of coherent photoproduction of $K^{+}{K}^{-}$ pairs on lead ions in ultraperipheral collisions using the ALICE detector, including the first investigation of direct $K^{+}{K}^{-}$ production. There is significant $K^{+}{K}^{-}$ production at low transverse momentum, consistent with coherent photoproduction on lead targets. In the mass range $1.1<M_{KK}<1.4\mathrm{GeV}/c^2$ above the $\varphi \left(1020\right)$ resonance, for rapidity $\left|y_{KK}\right|<0.8$ and $p_{T,KK}<0.1\mathrm{GeV}/c$ , the measured coherent photoproduction cross section is $\mathrm{d}\sigma /\mathrm{d}y=3.37\pm 0.61\left(\text{stat}\right)\pm 0.15\left(\mathrm{syst}\right)\mathrm{mb}$ . The center-of-mass energy per nucleon of the photon-nucleus (Pb) system $W_{\gamma \mathrm{Pb},n}$ ranges from 33 to 188 GeV, far higher than previous measurements on heavy-nucleus targets. The cross section is larger than expected for $\varphi \left(1020\right)$ photoproduction alone. The mass spectrum is fit to a cocktail consisting of $\varphi \left(1020\right)$ decays, direct $K^{+}{K}^{-}$ photoproduction, and interference between the two. The confidence regions for the amplitude and relative phase angle for direct $K^{+}{K}^{-}$ photoproduction are presented. © 2024 CERN, for the ALICE Collaboration2024CERN 

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