arXiv subjects

Chun Du

Publications and source records attributed to Chun Du.

11 recordsLinked to original sources

arXiv2024

Assisting Tibetan Students in Learning Quantum Mechanics via Mathematica

Undergraduate students of physics in Tibet have great difficulty learning quantum mechanics (QM). We attempt to use PER-based methods to help Tibetan students learn QM. In this preliminary study, we incorporate Mathematica in a QM course at Tibet University and record students' learning experiences. Tibetan students tend to have subjective feelings of learning Mathematica, whereas Han students (majority) are more focused on the operational techniques of Mathematica. The results also suggest that both Tibetan students and Han students show limited improvement in time-independent Schrodinger equations after learning QM with Mathematica. Further effort is needed to improve the academic literacy skills of physics students in Tibet.

physics.ed-ph↗

arXiv2024

NeRF as a Non-Distant Environment Emitter in Physics-based Inverse Rendering

Physics-based inverse rendering enables joint optimization of shape, material, and lighting based on captured 2D images. To ensure accurate reconstruction, using a light model that closely resembles the captured environment is essential. Although the widely adopted distant environmental lighting model is adequate in many cases, we demonstrate that its inability to capture spatially varying illumination can lead to inaccurate reconstructions in many real-world inverse rendering scenarios. To address this limitation, we incorporate NeRF as a non-distant environment emitter into the inverse rendering pipeline. Additionally, we introduce an emitter importance sampling technique for NeRF to reduce the rendering variance. Through comparisons on both real and synthetic datasets, our results demonstrate that our NeRF-based emitter offers a more precise representation of scene lighting, thereby improving the accuracy of inverse rendering.

cs.CV↗

arXiv2023

Robust Power Allocation for Integrated Visible Light Positioning and Communication Networks

Integrated visible light positioning and communication (VLPC), capable of combining advantages of visible light communications (VLC) and visible light positioning (VLP), is a promising key technology for the future Internet of Things. In VLPC networks, positioning and communications are inherently coupled, which has not been sufficiently explored in the literature. We propose a robust power allocation scheme for integrated VLPC Networks by exploiting the intrinsic relationship between positioning and communications. Specifically, we derive explicit relationships between random positioning errors, following both a Gaussian distribution and an arbitrary distribution, and channel state information errors. Then, we minimize the Cramer-Rao lower bound (CRLB) of positioning errors, subject to the rate outage constraint and the power constraints, which is a chance-constrained optimization problem and generally computationally intractable. To circumvent the nonconvex challenge, we conservatively transform the chance constraints to deterministic forms by using the Bernstein-type inequality and the conditional value-at-risk for the Gaussian and arbitrary distributed positioning errors, respectively, and then approximate them as convex semidefinite programs. Finally, simulation results verify the robustness and effectiveness of our proposed integrated VLPC design schemes.

cs.IT↗

arXiv2022

Joint Beamforming and PD Orientation Design for Mobile Visible Light Communications

In this paper, we propose joint beamforming and photo-detector (PD) orientation (BO) optimization schemes for mobile visible light communication (VLC) with the orientation adjustable receiver (OAR). Since VLC is sensitive to line-of-sight propagation, we first establish the OAR model and the human body blockage model for mobile VLC user equipment (UE). To guarantee the quality of service (QoS) of mobile VLC, we jointly optimize BO with minimal UE the power consumption for both fixed and random UE orientation cases. For the fixed UE orientation case, since the {transmit} beamforming and the PD orientation are mutually coupled, the joint BO optimization problem is nonconvex and intractable. To address this challenge, we propose an alternating optimization algorithm to obtain the transmit beamforming and the PD orientation. For the random UE orientation case, we further propose a robust alternating BO optimization algorithm to ensure the worst-case QoS requirement of the mobile UE. Finally, the performance of joint BO optimization design schemes are evaluated for mobile VLC through numerical experiments.

eess.SP↗

arXiv2019

Signal Demodulation with Machine Learning Methods for Physical Layer Visible Light Communications: Prototype Platform, Open Dataset and Algorithms

In this paper, we investigate the design and implementation of machine learning (ML) based demodulation methods in the physical layer of visible light communication (VLC) systems. We build a flexible hardware prototype of an end-to-end VLC system, from which the received signals are collected as the real data. The dataset is available online, which contains eight types of modulated signals. Then, we propose three ML demodulators based on convolutional neural network (CNN), deep belief network (DBN), and adaptive boosting (AdaBoost), respectively. Specifically, the CNN based demodulator converts the modulated signals to images and recognizes the signals by the image classification. The proposed DBN based demodulator contains three restricted Boltzmann machines (RBMs) to extract the modulation features. The AdaBoost method includes a strong classifier that is constructed by the weak classifiers with the k-nearest neighbor (KNN) algorithm. These three demodulators are trained and tested by our online open dataset. Experimental results show that the demodulation accuracy of the three data-driven demodulators drops as the transmission distance increases. A higher modulation order negatively influences the accuracy for a given transmission distance. Among the three ML methods, the AdaBoost modulator achieves the best performance.

eess.SP↗

arXiv2019

Further study of the global minimum constraint on the two-Higgs-doublet models: LHC searches for heavy Higgs bosons

The usually considered vacuum of the two-Higgs-doublet model (2HDM) could be unstable if it locates at a local but not global minimum (GM) of the scalar potential. By requiring the vacuum to be a GM, we obtain an additional constraint, namely the GM constraint, on the scalar potential. In this work, we explore the GM constraint on the $CP$-conserving general 2HDM. This constraint is found to put limits on the soft $\mathbb{Z}_2$ breaking mass parameter $m_{12}^2$ and also squeeze the heavy $CP$-even Higgs boson mass into larger values for the $m_{12}^2< 0$ case. Combined with the current global signal fits from the LHC measurements of the 125 GeV Higgs boson, we discuss the phenomenological implications for the heavy Higgs boson searches at the LHC.

hep-ph↗

arXiv2016

Searching for Heavier Higgs Boson via Di-Higgs Production at LHC Run-2

The LHC discovery of a light Higgs particle $h^0$ (125GeV) opens up new prospect for searching heavier Higgs boson(s) at the LHC Run-2, which will unambiguously point to new physics beyond the standard model (SM). We study the detection of a heavier neutral Higgs boson $H^0$ via di-Higgs production channel at the LHC (14TeV), $H^0 \to h^0h^0 \to WW^*γγ$. This directly probes the $Hhh$ cubic Higgs interaction, which exists in most extensions of the SM Higgs sector. For the decay products of final states $WW^*$, we include both pure leptonic mode $WW^* \to \ell\barν\bar{\ell}ν$ and semi-leptonic mode $WW^* \to q\bar{q}'\ellν$. We analyze signals and backgrounds by performing fast detector simulation for the full processes $pp \to H \to hh \to WW^*γγ\to \ell\barν\bar{\ell}νγγ$ and $pp \to H \to hh \to WW^*γγ\to \ellνq\bar{q}'γγ$, over the mass range $M_H=250-600$GeV. For generic two-Higgs-doublet models (2HDM), we present the discovery reach of the heavier Higgs boson at the LHC Run-2, and compare it with the current Higgs global fit of the 2HDM parameter space.

hep-ph↗

arXiv2014

LHC Searches for The Heavy Higgs Boson via Two B Jets plus Diphoton

Extra scalar fields are common in beyond Standard Model (SM) new physics, and they may mix with the 125 GeV SM-like Higgs boson discovered at the LHC. This fact suggests possible discovery channels for these new scalar fields with their decay modes involving the 125 GeV Higgs boson. In this work, we explore the LHC search potential of the heavy CP-even Higgs boson H in the two-Higgs-doublet model. We focus on the channel of H decaying to a pair of light CP-even Higgs bosons h, with two h's decaying to two b jets and diphoton sequentially. This channel is particularly involved when the relevant cubic coupling is enhanced. We find such enhancement to be possible when taking a large CP-odd Higgs mass input for the two-Higgs-doublet model spectrum. Analogous to the SM Higgs self-coupling measurement, the two b jets plus diphoton final states are of particular interest due to the manageable SM background. After performing a cut-based analysis of both signal and background processes, we demonstrate the LHC search sensitivities for the heavy CP-even Higgs boson in a broad mass range via the two b jets plus diphoton final states.

hep-ph↗

arXiv2013

LHC Higgs Signatures from Topflavor Seesaw Mechanism

We study LHC Higgs signatures from topflavor seesaw realization of electroweak symmetry breaking with a minimal gauge extension SU(2) x SU(2) x U(1). This elegant renormalizable construction singles out top quark sector (instead of all other light fermions) to join the new SU(2) gauge force. It predicts extra vector-like spectator quarks (T, B), new gauge bosons (W', Z'), and a pair of neutral Higgs bosons (h, H). We demonstrate that for the lighter Higgs boson h of mass 125GeV, this model predicts modified Higgs signal rates in h --> γγ, WW*, ZZ* channels via gluon fusions, in h --> tau tau mode via vector boson fusions, and in h --> bb mode via gauge boson associate productions. We perform a global fit for our theory by including both direct search data (LHC and Tevatron) and indirect precision constraints. We further analyze the LHC discovery potential for detecting the heavier Higgs state H.

hep-ph↗

arXiv2013

Vector Bosons Signals of Electroweak Symmetry Breaking

We study the physics potential of the 8 TeV LHC to discover signals of extended gauge models or extra dimensional models whose low energy behavior is well represented by an SU(2) x SU(2) x U(1) electroweak gauge structure. We find that with a combined integrated luminosity of 40 fb^(-1), the first new Kaluza-Klein mode of the W gauge boson can be discovered up to a mass of about 400 GeV, when produced in association with a Z boson.

hep-ph↗

arXiv2012

Discovering New Gauge Bosons of Electroweak Symmetry Breaking at LHC-8

We study the physics potential of the 8TeV LHC (LHC-8) to discover, during its 2012 run, a large class of extended gauge models or extra dimensional models whose low energy behavior is well represented by an SU(2)^2 x U(1) gauge structure. We analyze this class of models and find that with a combined integrated luminosity of 40-60/fb at the LHC-8, the first new Kaluza-Klein mode of the W gauge boson can be discovered up to a mass of about 370-400 GeV, when produced in association with a Z boson.

hep-ph↗