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The original Belle II HLT framework was formally upgraded replacing the old IPC based ring buffer with the ZeroMQ data transport to overcome the unexpected IPC locking problem. The new framework has been working stably in the beam run so far, but it lacks the capability to recover the processing fault without stopping the on-going data taking. In addition, the compatibility with the offline framework ( basf2 ) was lost which was maintained in the original. In order to solve these, an improved core processing framework is developed based on original basf2 , while keeping the existing ZeroMQ data transport between the servers unchanged. A new core framework zmq-basf2 is developed with a lock-free 1-to-N and N-to-1 data transport using the ZeroMQ IPC socket so that it keeps a 100% compatibility with the original ring-buffer based framework. When a processing fault occurs, the affected faulty event is salvaged from the input buffer and sent directly to the output using the ZeroMQ broadcast. The terminated process is automatically restarted without stopping data taking. This contribution describes the detail of the improved Belle II HLT framework with the result of the performance test in the real Belle II DAQ data flow.

The backend of the Belle II data acquisition system consists of a high-level trigger system, online storage, and an express-reconstruction system for online data processing. The high-level trigger system was updated to use the ZeroMQ networking library from the old ring buffer and TCP/IP socket, and the new system is successfully operated. However, the online storage and express-reconstruction system use the old type of data transportation. For future maintainability, we expand the same ZeroMQ library-based system to the online storage and express-reconstruction system. At the same time, we introduce two more updates in the backend system. First, online side raw data output becomes compressed ROOT format which is the official format of the Belle II data. The update helps to reduce the bandwidth of the online to offline data transfer and offline-side computing resource usage for data format conversion and compression. Second, high-level trigger output-based event selection is included in the online storage. The event selection allows more statistics of data quality monitoring from the express-reconstruction system. In the presentation, we show the description and test result of the upgrade before applying it to the beam operation and data taking.

At high luminosity flavor factory experiments such as Belle II, global analyses with many observables are important to find new physics. Because the observables obtained by assuming the Standard Model could be changed by new physics effects in the kinematic distribution, such effects must be estimated with the detector simulation. We develop the event generator of B → K * ll decays including new physics effects in the model-independent way by parametrizing with the Wilson coefficients based on the EvtGen and EOS. An example of the kinematic distribution is shown, including possible new physics effects in Wilson coefficients.

The polarization of relativistic jets is of interest for the understanding of their origin, confinement, and propagation. However, even though numerous measurements have been performed, the mechanisms behind jet variability, creation, and composition are still debated. We have performed simultaneous gamma-ray and optical photopolarimetry observations of 45 blazars with the Kanata telescope since July 2008 to investigate the mechanisms of variability and search for a basic relation between the several subclasses of relativistic jets. Consequently, we found that a correlation between the gamma-ray and optical flux might be related to gamma-ray luminosity, and the maximum polarization degree might be related to gamma-ray luminosity or the ratio of gamma-ray to optical flux. These results imply that low gamma-ray luminosity blazars emit from multiple regions.

Optical polarization provides important clues to the magnetic field in blazar jets. It is easy to find noteworthy patterns in the time-series data of the polarization degree (PD) and position angle (PA). On the other hand, we need to see the trajectory of the object in the Stokes Q U plane when the object has multiple polarized components. In this case, ironically, the more data we have, the more difficult it is to gain any knowledge from it. Here, we introduce TimeTubes, a new visualization scheme to explore the time-series data of polarization observed in blazars. In TimeTubes, the data is represented by tubes in 3D (Q, U, and time) space. The measurement errors of Q and U, color, and total flux of objects are expressed as the size, color, and brightness of the tubes. As a result, TimeTubes allows us to see the behavior of six variables in one view. We used TimeTubes for our data taken by the Kanata telescope between 2008 and 2014. We found that this tool facilitates the recognition of the patterns in blazar variations; for example, favored PA of flares and PA rotations associated with a series of flares.

We propose and demonstrate a wavelength- and time-selective reconfigurable optical add/drop multiplexer (ROADM) using time-frequency domain processing. The proposed ROADM is realized by allocating wavelength channels and time slots to corresponding 2D spatial channels on a MEMS optical switch. Experimental results show the wavelength- and time-selective drop operation for a signal with equivalent 3.2 Tb/s (0.64  channels), and the reconfigurability by the switching operation of the MEMS optical switch.

S5 0716+714 is a well known BL Lac object, and one of the brightest and most active blazars. The discovery in the Very High Energy band (VHE, E > 100 GeV) by MAGIC happened in 2008. In January 2015, the source went through the brightest optical state ever observed, triggering MAGIC follow-up and a VHE detection with ∼ 13 σ significance (ATel ♯ 6999 ). Rich multiwavelength coverage of the flare allowed us to construct the broad-band spectral energy distribution of S5 0716+714 during its brightest outburst. In this work, we will present the preliminary analysis of MAGIC and Fermi-LAT data of the flaring activity in January and February 2015 for the HE (0.1 < HE < 300 GeV) and VHE band, together with radio (Metsähovi, OVRO, VLBA, Effelsberg), sub-millimeter (SMA), optical (Tuorla, Perkins, Steward, AZT-8+ST7, LX-200, Kanata), X-ray and UV (Swift-XRT and UVOT), in the same time-window and discuss the time variability of the multiwavelength light curves during this impressive outburst.

We present multi-wavelength studies of the radio galaxy 3C 120 and the blazar CTA 102 during unprecedented γ-ray flares for both sources. In both studies the analysis of γ-ray data has been compared with a series of 43 GHz VLBA images from the VLBA-BU-BLAZAR program, providing the necessary spatial resolution to probe the parsec scale jet evolution during the high energy events. To extend the radio dataset for 3C 120 we also used 15 GHz VLBA data from the MOJAVE sample. These two objects which represent very different classes of AGN, have similar properties during the γ-ray events. The γ-ray flares are associated with the passage of a new superluminal component through the mm VLBI core, but not all ejections of new components lead to γ-ray events. In both sources γ-ray events occurred only when the new components are moving in a direction closer to our line of sight. We locate the γ-ray dissipation zone a short distance from the radio core but outside of the broad line region, suggesting synchrotron self-Compton scattering as the probable mechanism for the γ-ray production.

The Fermi Gamma-ray Burst Monitor (GBM) triggers on-board in response to ∼40 short gamma-ray bursts (SGRBs) per year; however, their large localization regions have made the search for optical counterparts a challenging endeavour. We have developed and executed an extensive program with the wide field of view of the Zwicky Transient Facility (ZTF) camera, mounted on the Palomar 48 inch Oschin telescope (P48), to perform target-of-opportunity (ToO) observations on 10 Fermi-GBM SGRBs during 2018 and 2020–2021. Bridging the large sky areas with small field-of-view optical telescopes in order to track the evolution of potential candidates, we look for the elusive SGRB afterglows and kilonovae (KNe) associated with these high-energy events. No counterpart has yet been found, even though more than 10 ground-based telescopes, part of the Global Relay of Observatories Watching Transients Happen (GROWTH) network, have taken part in these efforts. The candidate selection procedure and the follow-up strategy have shown that ZTF is an efficient instrument for searching for poorly localized SGRBs, retrieving a reasonable number of candidates to follow up and showing promising capabilities as the community approaches the multi-messenger era. Based on the median limiting magnitude of ZTF, our searches would have been able to retrieve a GW170817-like event up to ∼200 Mpc and SGRB afterglows to z = 0.16 or 0.4, depending on the assumed underlying energy model. Future ToOs will expand the horizon to z = 0.2 and 0.7, respectively.