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  1. In this paper, we study the fragmentation of a heavy quark into a jet near threshold, meaning that final state jet carries most of the energy of the fragmenting heavy quark. Using the heavy quark fragmentation function, we simultaneously resum large logarithms of the jet radius R and 1 − z, where z is the ratio of the jet energy to the initiating heavy quark energy. There are numerically significant corrections to the leading order rate due to this resummation. We also investigate the heavy quark fragmentation to a groomed jet, using the soft drop grooming algorithm as an example. In order to do so, we introduce a collinear-ultrasoft mode sensitive to the grooming region determined by the algorithm’s zcut parameter. This allows us to resum large logarithms of zcut/(1−z), again leading to large numerical corrections near the endpoint. A nice feature of the analysis of the heavy quark fragmenting to a groomed jet is the heavy quark mass m renders the algorithm infrared finite, allowing a perturbative calculation. We analyze this for EJ R ∼ m and EJ R ≫ m, where EJ is the jet energy. To do the latter case, we introduce an ultracollinear-soft mode, allowing usmore »to resum large logarithms of EJ R/m. Finally, as an application we calculate the rate for e+e− collisions to produce a heavy quark jet in the endpoint region, where we show that grooming effects have a sizable contribution near the endpoint.« less
  2. Mid-infrared photonic integrated circuits (PICs) that combine on-chip light sources with other optical components constitute a key enabler for applications such as chemical sensing, light detection, ranging, and free-space communications. In this paper, we report the monolithic integration of interband cascade lasers emitting at 3.24 µm with passive, high-index-contrast waveguides made of chalcogenide glasses. Output from the chalcogenide waveguides exhibits pulsed peak power up to 150 mW (without roll-over), threshold current density 280 A/cm2, and slope efficiency 100 mW/A at 300 K, with a lower bound of 38% efficiency for coupling between the two waveguides. These results represent an important step toward the realization of fully integrated mid-infrared PICs.

  3. We present a neural interface system-on-chip (NISoC) with 1,024 channels of simultaneous electrical recording and stimulation for high-resolution high-throughput electrophysiology. The 2mm  2mm NISoC in 65nm CMOS integrates a 32  32 array of electrodes vertically coupled to analog front-ends supporting both voltage and current clamping through a programmable interface, ranging over 100dB in voltage and 120dB in current, with 0.82mW power per channel at 5.96mVrms input-referred voltage noise from DC to 12.5kHz signal bandwidth. This includes onchip acquisition with a back-end array of 32 dynamic incremental SAR ADCs for 25Msps 11-ENOB acquisition at 2fJ/level FOM.