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Based on a sample of 2.25 × 10 8 J/ψ events collected with the BESIII detector at BEPCII, a full partial wave analysis on J/ψ → γηη was performed using the relativistic covariant tensor amplitude method. The results show that the dominant 0 ++ and 2 ++ components are from the f0(1710), f0(2100), f0(1500), f ′ 2 (1525), f2(1810) and f2(2340). The resonance parameters and branching fractions are also presented.

Using 448.0 × 10 6 ψ(3686) events collected with the BESIII detector, an amplitude analysis is performed for ψ(3686) → γχc1, χc1 → ηπ + π − decays. The most dominant two-body structure observed is a0 (980) ± π ∓ ; a0(980) ± → ηπ ± . The a0(980) line shape is modeled using a dispersion relation, and a significant non-zero a0(980) coupling to the η ′ π channel is measured. We observe χc1 → a2(1700)π production for the first time, with a significance larger than 17σ. The production of mesons with exotic quantum numbers, J P C = 1 −+ , is investigated, and upper limits for the branching fractions χc1 → π1(1400) ± π ∓ , χc1 → π1(1600) ± π ∓ , and χc1 → π1(2015) ± π ∓ , with subsequent π1(X) ± → ηπ ± decay, are determined.

Recently twisted bilayer graphene(t-BLG) 1-5 emerges as a new strongly correlated physical platform near a magic twist angle 4 , which hosts many exciting phenomena such as the Mott-like insulating and unconventional superconducting behavior [6][7][8][9][10] . Besides the apparent significance of band flatness 4 , band topology may be another critical element in strongly correlated twistronics yet receives much less attention [11][12][13][14] . Here we report the discovery of nontrivial high dimensional band topology in t-BLG moiré bands through a systematic nonlocal transport study 15,16 , in conjunction with an examination rooted in K-theory 17 . The moiré band topology of t-BLG manifests itself as two pronounced nonlocal responses in the electron and hole superlattice gaps.We further show that the nonlocal responses are robust to the interlayer electric field, twist angle, and edge termination, exhibiting a universal scaling law. While an unusual symmetry of t-BLG trivializes Berry curvature, we elucidate that two high dimensional Z2 invariants characterize the topology of the moiré Dirac bands, validating the topological origin of the observed nonlocal responses. Our findings not only provide a new perspective for understanding the emerging strongly correlated phenomena in twisted van der Waals heterostructures, but also suggest a potential strategy to achieve topologically nontrivial metamaterials from topologically trivial quantum materials based on twist engineering.

Abstract-In this letter, we propose a modulation classification algorithm which is based on the received signal's amplitude for coherent optical receivers. The proposed algorithm classifies the modulation format from several possible candidates by differentiating the cumulative distribution function (CDF) curves of their normalized amplitudes. The candidate with the most similar CDF to the received signal is selected. The measure of similarity is the minimum average distance between these CDFs. Five commonly used quadrature amplitude modulation formats in digital coherent optical systems are employed. Optical backto-back experiments and extended simulations are carried out to investigate the performance of the proposed algorithm. Results show that the proposed algorithm achieves accurate classification at optical signal-to-noise ratios of interest. Furthermore, it does not require carrier recovery.