A note on modular forms and generalized anomaly cancellation formulas

By studying modular invariance properties of some characteristic forms, we prove some new anomaly cancellation formulas which generalize the Han-Zhang and Han-Liu-Zhang anomaly cancellation formula

Train Monitoring using GSM-R Based Passive Radar

Train detection technologies are universal to all modern railway signal and control systems. They are essential for managing the movement of vehicles across entire transport networks, and to ensure their safe operation. In this paper we investigate the feasibility of a new train monitoring capability based on passive radar technology. The system exploits signal transmissions from the railways’ GSM-Railway (GSM-R) radio communications infrastructure, and has the potential to determine the positions and velocities of trains over any section of a railway network where there is GSM-R coverage. A theoretical ambiguity function analysis on directly measured GSM-R waveforms suggest that targets can be detected with axial range resolutions of approximately 850 m, and velocities down to less than 1 mph. To demonstrate proof-of-concept, a series of experiments were carried out using a software-defined GSM-R passive radar system. The results show the first detections of trains at bistatic ranges of just over 1 km moving at various speeds. There are now hundreds of thousands of miles of railway track covered by GSM-R globally, with many more countries planning to rollout systems nationally. The results therefore imply that GSM-R based passive radar technology could be used to develop low-cost train monitoring capabilities worldwide alongside the existing GSM-R radio communications infrastructure

Does SN 1987A contain a rapidly vibrating neutron star

If the recently reported 0.5 ms-period pulsed optical signal from the direction of Supernova 1987A originated in a young neutron star, its interpretation as a rotational period has difficulties. The surface magnetic field would have to be much lower than expected, and the high rotation rate may rule out preferred nuclear equations of state. It is pointed out here that a remnant radial vibration of a neutron star, excited in the supernova event, may survive for several years with about the observed (gravitationally redshifted) period. Heavy ions at the low-density stellar surface, periodically shocked by the vibration, may efficiently produce narrow pulses of optical cyclotron radiation in a surface field of about a trillion gauss

H-Dihyperon in Quark Cluster Model

The H dihyperon (DH) is studied in the framework of the SU(3) chiral quark model. It is shown that except the $\sigma$ chiral field, the overall effect of the other SU(3) chiral fields is destructive in forming a stable DH. The resultant mass of DH in a three coupled channel calculation is ranged from 2225 $MeV$ to 2234 $MeV$.Comment: 9 pages, emte