{"ID":6497704,"CreatedAt":"2026-07-13T01:19:40.13847098Z","UpdatedAt":"2026-07-14T01:36:59.12045529Z","DeletedAt":null,"paper_url":"https://arxiv.org/abs/2607.09347","arxiv_id":"2607.09347","title":"Commissioning and Low Latency Operation of the Graph Neural Network Electromagnetic Calorimeter Trigger at the Belle II Experiment","abstract":"We present the commissioning and operation of the Graph Neural Network Electromagnetic Calorimeter Trigger Module (GNN-ETM) of the Belle II experiment at the SuperKEKB collider. The GNN-ETM processes calorimeter trigger cells as graph nodes to perform clustering and feature extraction. We fully integrate the system with the successive stages of the first-level trigger, develop slow-control drivers, and add online monitoring capabilities. We optimise the existing FPGA-based architecture through hardware-algorithm co-design, achieving an overall system latency of 1.053 us. Our hardware implementation is validated through register-transfer-level simulations, achieving bit-accurate agreement with the offline reference model. Online monitoring enables the measurement of instantaneous trigger rates, providing a quantitative basis for trigger-level performance studies. In summary, we report on the GNN-ETM as a fully operational, low-latency trigger module with online control and monitoring capabilities, compatible with the latency requirements of the Belle II first-level trigger system.","short_abstract":"We present the commissioning and operation of the Graph Neural Network Electromagnetic Calorimeter Trigger Module (GNN-ETM) of the Belle II experiment at the SuperKEKB collider. The GNN-ETM processes calorimeter trigger cells as graph nodes to perform clustering and feature extraction. We fully integrate the system wit...","url_abs":"https://arxiv.org/abs/2607.09347","url_pdf":"https://arxiv.org/pdf/2607.09347v1","authors":"[\"M. Neu\",\"F. Baptist\",\"I. Haide\",\"Y. Unno\",\"J. Becker\",\"T. Ferber\",\"K. Arai\",\"Y. -T. Lai\",\"T. Koga\",\"M. Maushart\",\"H. Nakazawa\",\"V. Savinov\",\"K. Unger\"]","published":"2026-07-10T12:28:48Z","proceeding":"hep-ex","tasks":"[\"hep-ex\",\"eess.SP\"]","methods":"[\"Graph Neural Network\"]","has_code":false}