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Yuanyuan Ma

Publications and source records attributed to Yuanyuan Ma.

9 recordsLinked to original sources

$B\to PP$ decays with Light-Cone Sum Rules

We study factorizable contributions to two-body nonleptonic decays of $B$ mesons using the light-cone sum rule method. By constructing three-point correlation functions and incorporating light-cone distribution amplitudes, we compute the hadronic matrix elements and branching ratios for decay channels $B^0 \to \pi^+\pi^-$, $B^+ \to \pi^+\pi^0$, $B^0 \to K^+\pi^-$, and $B^0 \to K^+K^-$. The results are in agreement with experimental data within uncertainties. We also estimate the branching ratio of $B_s^0 \to \pi^+\pi^-$ to be approximately $0.781\times10^{-6}$.

hep-ph

Study on the Distribution Amplitude of the Scalar Meson $K_0^*(1430)$

Based on sum rules, we explore the twist-2 distribution amplitude of the $K_0^*(1430)$ meson, treating it as the ground state of a quark-antiquark system. We posit that the spacetime distance $x$ should be infinitesimally close to the quark separation $ z$. By incorporating quark distance corrections, with $x^2 \approx z^2 \approx x z$, the calculated moments yield additional insights. Moreover, we employ light-cone sum rules to compute the form factors for the semi-leptonic decay process $B_s \rightarrow K$. The reliability of the computed distribution amplitude is confirmed through its comparison with the form factor.

hep-ph

Investigating and Controlling the Libration and Rotation Dynamics of Nanoparticles in an Optomechanical System

In optomechanical systems, the libration and rotation of nanoparticles offer profound insights for ultrasensitive torque measurement and macroscopic quantum superpositions. Achievements include transitioning libration to rotation up to 6 GHz and cooling libration to millikelvin temperatures. It is undoubted that the libration and rotation are respectively driven by restoring and constant optical torques. The transition mechanisms between these two states, however, demand further exploration. In this perspective, it is demonstrated in this manuscript that monitoring lateral-scattered light allows real-time observation of libration/rotation transitions and associated hysteresis as ellipticities of trapping laser fields vary. By calculating optical torques and solving the Langevin equation, transitions are linked to the balance between anisotropic-polarization-induced sinusoidal optical torques and constant ones, with absorption identified as the main contributor to constant torques. These findings enable direct weak torque sensing and precise nanoparticle control in rotational degrees, paving the way for studying quantum effects like nonadiabatic phase shifts and macroscopic quantum superpositions, thereby enriching quantum optomechanics research.

physics.optics

Morphological tracking and tuning of silica NPs for stable levitation in vacuum optomechanical systems

Optically levitated nanomechanical resonators in vacuum perform ultrahigh sensitivity for mechanical quantities by overcoming the limitations of clamped resonators. However, the generally levitated silica nanoparticles (NPs) with low absorption and high transparence still face difficulties surviving in high vacuum with unclear reason. By monitoring the physicochemical properties like scattering, mass and density of amorphous silica NPs during pumping process. we propose that the loss of NPs may arises from the motional instability induced by laser heating lead releasing at low pressure. In this work, two types of NPs are heat treated from 100 to 1200 degree Celsius to release impurities before being loaded into an optical trap. The high vacuum levitation ratio for both NPs increase obviously after heat treatment. In particular, for NPs heated to 600 degree Celsius, the ratio strikingly improves from ~30% to 100% and ~0 to 85% for two types of NPs. The loss mechanism is further confirmed by their relatively stable physicochemical parameters during pumping process. This work paves a way for wide application of levitated nano-resonators and indicates that levitated vacuum optomechanical systems could be a promising tool for dynamics and in-situ studying of small particles like aerosols and dusts.

physics.optics

On Secure Uplink Transmission in Hybrid RF-FSO Cooperative Satellite-Aerial-Terrestrial Networks

This work investigates the secrecy outage performance of the uplink transmission of a radio-frequency (RF)-free-space optical (FSO) hybrid cooperative satellite-aerial-terrestrial network (SATN). Specifically, in the considered cooperative SATN, a terrestrial source (S) transmits its information to a satellite receiver (D) via the help of a cache-enabled aerial relay (R) terminal with the most popular content caching scheme, while a group of eavesdropping aerial terminals (Eves) trying to overhear the transmitted confidential information. Moreover, RF and FSO transmissions are employed over S-R and R-D links, respectively. Considering the randomness of R, D, and Eves, and employing a stochastic geometry framework, the secrecy outage performance of the cooperative uplink transmission in the considered SATN is investigated and a closed-form analytical expression for the end-to-end secrecy outage probability is derived. Finally, Monte-Carlo simulations are shown to verify the accuracy of our analysis.

eess.SP

Effect of Strong Time-Varying Transmission Distance on LEO Satellite-Terrestrial Deliveries

In this paper, we investigate the effect of the strong time-varying transmission distance on the performance of the low-earth orbit (LEO) satellite-terrestrial transmission (STT) system. We propose a new analytical framework using finite-state Markov channel (FSMC) model and time discretization method. Moreover, to demonstrate the applications of the proposed framework, the performances of two adaptive transmissions, rate-adaptive transmission (RAT) and power-adaptive transmission (PAT) schemes, are evaluated for the cases when the transmit power or the transmission rate at the LEO satellite is fixed. Closed-form expressions for the throughput, energy efficiency (EE), and delay outage rate (DOR) of the considered systems are derived and verified, which are capable of addressing the capacity, energy efficiency, and outage rate performance of the considered LEO STT scenarios with the proposed analytical framework.

eess.SP

Multi-view Subspace Clustering Networks with Local and Global Graph Information

This study investigates the problem of multi-view subspace clustering, the goal of which is to explore the underlying grouping structure of data collected from different fields or measurements. Since data do not always comply with the linear subspace models in many real-world applications, most existing multi-view subspace clustering methods that based on the shallow linear subspace models may fail in practice. Furthermore, underlying graph information of multi-view data is always ignored in most existing multi-view subspace clustering methods. To address aforementioned limitations, we proposed the novel multi-view subspace clustering networks with local and global graph information, termed MSCNLG, in this paper. Specifically, autoencoder networks are employed on multiple views to achieve latent smooth representations that are suitable for the linear assumption. Simultaneously, by integrating fused multi-view graph information into self-expressive layers, the proposed MSCNLG obtains the common shared multi-view subspace representation, which can be used to get clustering results by employing the standard spectral clustering algorithm. As an end-to-end trainable framework, the proposed method fully investigates the valuable information of multiple views. Comprehensive experiments on six benchmark datasets validate the effectiveness and superiority of the proposed MSCNLG.

cs.LG

Predictive Precompute with Recurrent Neural Networks

In both mobile and web applications, speeding up user interface response times can often lead to significant improvements in user engagement. A common technique to improve responsiveness is to precompute data ahead of time for specific activities. However, simply precomputing data for all user and activity combinations is prohibitive at scale due to both network constraints and server-side computational costs. It is therefore important to accurately predict per-user application usage in order to minimize wasted precomputation ("predictive precompute"). In this paper, we describe the novel application of recurrent neural networks (RNNs) for predictive precompute. We compare their performance with traditional machine learning models, and share findings from their large-scale production use at Facebook. We demonstrate that RNN models improve prediction accuracy, eliminate most feature engineering steps, and reduce the computational cost of serving predictions by an order of magnitude.

cs.LG

An Iterative Method Applied to Correct the Actual Compressor Performance to the Equivalent Performance under the Specified Reference Conditions

This paper proposes a correction method, which corrects the actual compressor performance in real operating conditions to the equivalent performance under specified reference condition. The purpose is to make fair comparisons between actual performance against design performance or reference maps under the same operating conditions. Then the abnormal operating conditions or early failure indications can be identified through condition monitoring, which helps to avoid mandatory shutdown and reduces maintenance costs. The corrections are based on an iterative scheme, which simultaneously correct the main performance parameters known as the polytropic head, the gas power, and the polytropic efficiency. The excellent performance of the method is demonstrated by performing the corrections over real industrial measurements.

eess.SY