Jet-Origin Identification and Its Application at an Electron-Positron Higgs Factory.

To enhance the scientific discovery power of high-energy collider experiments, we propose and realize the concept of jet-origin identification that categorizes jets into five quark species (b,c,s,u,d), five antiquarks (b[over ¯],c[over ¯],s[over ¯],u[over ¯],d[over ¯]), and the gluon. Using state-of-the-art algorithms and simulated νν[over ¯]H,H→jj events at 240 GeV center-of-mass energy at the electron-positron Higgs factory, the jet-origin identification simultaneously reaches jet flavor tagging efficiencies ranging from 67% to 92% for bottom, charm, and strange quarks and jet charge flip rates of 7%-24% for all quark species. We apply the jet-origin identification to Higgs rare and exotic decay measurements at the nominal luminosity of the Circular Electron Positron Collider and conclude that the upper limits on the branching ratios of H→ss[over ¯],uu[over ¯],dd[over ¯] and H→sb,db,uc,ds can be determined to 2×10^{-4} to 1×10^{-3} at 95% confidence level. The derived upper limit for H→ss[over ¯] decay is approximately 3 times the prediction of the standard model.

Relativistic-guided stable mode of few-cycle 20 µm level infrared radiation.

The generation of intense infrared radiation with a wavelength greater than 10 µm is limited by the optical materials in traditional methods or the laser-plasma parameters of plasma-bubble methods. In this study, we propose a new method for generating an intense longitudinal radiation field of tens of GV/m. By utilizing the oscillations of the electron film on the inner surface of the micro-tube, excited by the relativistic electron beam propagating within it, it is possible to obtain tunable long-wavelength few-cycle infrared radiation, ranging from 20 to 30 µm and even longer. The radiation source is guided entirely by a relativistic electron beam and formed a stable TM propagation mode in the micro-tube. This opens up new opportunities for applications of the relativistic intensity infrared radiation to high-field physics, shorter attosecond pulses generation and charged particle acceleration.

Fractal dimension of particle showers measured in a highly granular calorimeter.

We explore the fractal nature of particle showers using Monte Carlo simulation. We define the fractal dimension of showers measured in a high granularity calorimeter designed for a future lepton collider. The shower fractal dimension reveals detailed information of the spatial configuration of the shower. It is found to be characteristic of the type of interaction and highly sensitive to the nature of the incident particle. Using the shower fractal dimension, we demonstrate a particle identification algorithm that can efficiently separate electromagnetic showers, hadronic showers, and nonshowering tracks. We also find a logarithmic dependence of the shower fractal dimension on the particle energy.

The circular electron-positron collider beam energy measurement with Compton scattering and beam tracking method.

The beam energy of the circular electron-positron collider should be measured precisely to the order of 1 MeV, in order to decrease the uncertainty of the Higgs/W/Z bosons' mass measurement. For this purpose, a lepton bunch is extracted from the collider and collides with an Yttrium-Aluminum-Garnet laser pulse. After the inverse Compton scattering, the main beam and the scattered beam pass through an analytical magnetic field and are deflected to different angles. At the end of the drift beam pipes, the deflecting distances are detected with the spatial resolution of several microns. The systematic uncertainties caused by the detector arrangement, the magnetic field, the angle between the detector plane and the incident beam, and the synchrotron radiation are discussed in detail. The simulations of the statistical errors are given with a toy Monte Carlo sample. With some proper corrections, the beam energy uncertainty of the Higgs mode is around 2 MeV. Our method is applicable to different operating modes of the collider.

[Simultaneous measurement of muscle energy metabolism by MRS and frequency-domain NIR spectroscopy].

The frequency-domain near-infrared spectrometry (NIRS) is capable of measuring the absolute absorption and reduced scattering coefficient of tissue noninvasively. This allows the quantitation of tissue hemoglobin concentration which reflects the balance between oxygen delivery and oxygen utilization of the skeletal muscle. Phosphorus magnetic resonance spectroscopy (31P-MRS) has become a gold standard of noninvasive measurement of human skeletal muscle metabolism. The rate of phosphocreatine (PCr) resynthesis during recovery is an indicator of the rate of oxidative metabolism. The purpose of the present study was the effect of lower intracellular pH (pHi) on PCr and oxygenation recovery. The preliminary results of plantar flexion experiment on a healthy male subject show that both PCr resynthesis and reoxygenation were very much prolonged by severe acidosis (pHi = 6.42).