Electron Monte Carlo Simulations of Nanoporous Si Thin Films -- The Influence of Pore-Edge Charges

Electron transport within nanostructures can be important to varied engineering applications, such as thermoelectrics and nanoelectronics. In theoretical studies, electron Monte Carlo simulations are widely used as an alternative approach to solving the electron Boltzmann transport equation, where the energy-dependent electron scattering, exact structure shape, and detailed electric field distribution can be fully incorporated. In this work, such electron Monte Carlo simulations are employed to predict the electrical conductivity of periodic nanoporous Si films that have been widely studied for thermoelectric applications. The focus is on the influence of pore-edge charges on the electron transport. The results are further compared to our previous modeling [Hao et al., J. Appl. Phys. 121, 094308 (2017)], where the pore-edge electric field has its own scattering rate to be added to the scattering rates of other mechanisms

A Cosmic Selection Rule for Glueball Dark Matter Relic Density

We point out a unique mechanism to produce the relic abundance for glueball dark matter from a gauged $SU(N)_d$ hidden sector which is bridged to the standard model sector through heavy vectorlike quarks colored under gauge interactions from both sides. A necessary ingredient of our assumption is that the vectorlike quarks, produced either thermally or non-thermally, are abundant enough to dominate the universe for some time in the early universe. They later undergo dark color confinement and form unstable vectorlike-quarkonium states which annihilate decay and reheat the visible and dark sectors. The ratio of entropy dumped into two sectors and the final energy budget in the dark glueballs is only determined by low energy parameters, including the intrinsic scale of the dark $SU(N)_d$, $\Lambda_d$, and number of dark colors, $N_d$, but depend weakly on parameters in the ultraviolet such as the vectorlike quark mass or the initial condition. We call this a cosmic selection rule for the glueball dark matter relic density.Comment: 7 pages, 3 figures; v2 references added; v3 published versio

Performance Analysis of a Low-Interference N-Continuous OFDM Scheme

This paper investigates two issues of power spectrum density (PSD) and bit error rate (BER) of an N-continuous orthogonal frequency division multiplexing (NC-OFDM) aided low-interference time-domain scheme, when the smooth signal is designed by the linear combination of basis signals truncated by a window. Based on the relationship between the continuity and sidelobe decaying, the PSD performance is first analyzed and compared, in terms of the highest derivative order (HDO) N and the length of the smooth signal L. Since the high-order derivative of the truncation window has the finite continuity, the N-continuous signal has two finite continuities, which may have different continuous derivative orders. In this case, we develop a close PSD expression by introducing another smooth signal, which is also linearly combined by other basis signals, to explain the sidelobe decaying related to N and L. Then, in the context of BER, considering the multipath Rayleigh fading channel, based on the effect of the delayed tail of the smooth signal to the received signal, we provide a procedure for calculating the BER expressed in the form of an asymptotic summation.Comment: 7 pages, 6 figure

Gravitational waves with dark matter minispikes: the combined effect

It was shown that the dark matter(DM) minihalo around an intermediate mass black hole(IMBH) can be redistributed into a cusp, called the DM minispike. We consider an intermediate-mass-ratio inspiral consisting of an IMBH harbored in a DM minispike with nonannihilating DM particles and a small black hole(BH) orbiting around it. We investigate gravitational waves(GWs) produced by this system and analyze the waveforms with the comprehensive consideration of gravitational pull, dynamical friction and accretion of the minispike and calculate the time difference and phase difference caused by it. We find that for a certain range of frequency, the inspiralling time of the system is dramatically reduced for smaller central IMBH and large density of DM. For the central IMBH with $10^5M_\odot$, the time of merger is ahead, which can be distinguished by LISA, Taiji and Tianqin. We focus on the effect of accretion and compare it with that of gravitational pull and friction. We find that the accretion mass is a small quantity compared to the initial mass of the small BH and the accretion effect is inconspicuous compared with friction. However, the accumulated phase shift caused by accretion is large enough to be detected by LISA, Taiji and Tianqin, which indicate that the accretion effect can not be ignored in the detection of GWs.Comment: 10 pages, 14 figure