Results for "Yuan Feng"
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Accretion and ejection in Sgr A*Feb 16 2010We review our current understanding to the accretion and ejection processes in Sgr A*. Roughly speaking, they correspond to the quiescent and flare states of the source respectively. The high-resolution {\it Chandra} observations to the gas at the Bondi ... More Sivers Function in the MIT Bag ModelAug 14 2003The Sivers function, an asymmetric transverse-momentum distribution of the quarks in a transversely polarized nucleon, is calculated in the MIT bag model. The bag quark wave functions contain both $S$-wave and $P$-wave components, and their interference ... More Luminous hot accretion disksSep 13 2000Dec 05 2000We find a new two-temperature hot branch of equilibrium solutions for stationary accretion disks around black holes. In units of Eddington accretion rate defined as $10L_{\rm Edd}/c^2$, the accretion rates to which these solutions correspond are within ... More Accretion flows: the Role of the Outer Boundary ConditionJul 23 1999We investigate the influences of the outer boundary conditions(OBCs) on the structure of an optically thin accretion flow. We find that OBC plays an important role in determining the topological structure and the profiles of the surface density and temperature ... More Collins Asymmetry at Hadron CollidersJan 22 2008We study the Collins effect in the azimuthal asymmetric distribution of hadrons inside a high energy jet in the single transverse polarized proton proton scattering. From the detailed analysis of one-gluon and two-gluon exchange diagrams contributions, ... More A New Parameter In Accretion Disk ModelFeb 03 2000Taking optically thin accretion flows as an example, we investigate the dynamics and the emergent spectra of accretion flows with different outer boundary conditions (OBCs) and find that OBC plays an important role in accretion disk model. This is because ... More Accretion models of Sgr A*Jul 07 2006The supermassive black hole in the center of our Galaxy, Sgr A*, is unique because the angular size of the black hole is the largest in the sky thus providing detailed boundary conditions on, and much less freedom for, accretion flow models. In this paper ... More Generalized Parton Distributions at x->1Nov 22 2003Generalized parton distributions at large $x$ are studied in perturbative QCD approach. As $x\to 1$ and at finite $t$, there is no $t$ dependence for the GPDs which means that the active quark is at the center of the transverse space. We also obtain the ... More On hybrid models of quantum finite automataJun 11 2012Mar 27 2014In the literature, there exist several quantum finite automata (QFA) models with both quantum and classical states. These models are of particular interest,as they show praiseworthy advantages over the fully quantum models in some nontrivial aspects. ... More Model Checking Quantum Systems --- A SurveyJul 25 2018This article discusses the essential difficulties in developing model-checking techniques for quantum systems that are never present in model checking classical systems. It further reviews some early researches on checking quantum communication protocols ... More Hot Accretion Flows Around Black HolesJan 03 2014Black hole accretion flows can be divided into two broad classes: cold and hot. Cold accretion flows, which consist of cool optically thick gas, are found at relatively high mass accretion rates. Prominent examples are the standard thin disk, which occurs ... More Observational evidence for AGNs feedback at parsec scaleMay 24 2011In a hot accretion flow, the radiation from the innermost region of the flow propagates outward and heats the electrons at large radii via Compton scattering. It has been shown in previous works that if the radiation is strong enough, $L\ga 2%L_{\rm Edd}$, ... More On the convective instability of hot radiative accretion flowsJan 20 2010Jun 11 2010How many fraction of gas available at the outer boundary can finally fall onto the black hole is an important question. It determines the observational appearance of accretion flows, and is also related with the evolution of black hole mass and spin. ... More Studying High Energy Final State Interactions by N/D MethodSep 07 1998Jan 26 1999We discuss the final state interaction effects at high energies via a multi-channel N/D method. We find that the 2 by 2 charge--exchange final state interactions typically contribute an enhancement factor of a few times $10^{-2}$ in the $B$ meson decay ... More Characterizing locally distinguishable orthogonal product statesJul 24 2007Bennett et al. \cite{BDF+99} identified a set of orthogonal {\em product} states in the $3\otimes 3$ Hilbert space such that reliably distinguishing those states requires non-local quantum operations. While more examples have been found for this counter-intuitive ... More Quantum loop programsMay 25 2006Jan 04 2007Loop is a powerful program construct in classical computation, but its power is still not exploited fully in quantum computation. The exploitation of such power definitely requires a deep understanding of the mechanism of quantum loop programs. In this ... More Acute Triangulations of the Cuboctahedral SurfaceSep 20 2012In this paper we prove that the surface of the cuboctahedron can be triangulated into 8 non-obtuse triangles and 12 acute triangles. Furthermore, we show that both bounds are the best possible. Episodic Jets as the Central Engine of Gamma-Ray BurstsJul 26 2012Most Gamma-ray bursts (GRBs) have erratic light curves, which demand that the GRB central engine launches an episodic outflow. Recent Fermi observations of some GRBs indicate a lack of the thermal photosphere component as predicted by the baryonic fireball ... More Rapidity dependence of large-p_t hadron production at RHICAug 24 2001We study the dependence of parton energy loss (quenching) on rapidity in ultra-relativistic nuclear collisions at RHIC. This can provides invaluable information on the density of the medium, which should be more dilute going away from mid-rapidity, thereby ... More Global Neutrino Heating in Hyperaccretion FlowsJan 07 2013Feb 27 2013The neutrino-dominated accretion flow (NDAF) with accretion rates \dot{M} = 0.01 - 10 M_{\sun} s^{-1} is a plausible candidate for the central engine of gamma-ray bursts (GRBs). This hyperaccretion disk is optically thin to neutrinos in the radial direction, ... More Open Bisimulation for Quantum ProcessesJan 02 2012Quantum processes describe concurrent communicating systems that may involve quantum information. We propose a notion of open bisimulation for quantum processes and show that it provides both a sound and complete proof methodology for a natural extensional ... More Energy Evolution for the Sivers Asymmetries in Hard ProcessesApr 18 2013Aug 12 2013We investigate the energy evolution of the azimuthal spin asymmetries in semi-inclusive hadron production in deep inelastic scattering (SIDIS) and Drell-Yan lepton pair production in pp collisions. The scale dependence is evaluated by applying an approximate ... More NLO QCD Corrections to $B_c$-to-Charmonium Form FactorsMar 10 2011Apr 15 2012The $B_c(^1S_0)$ meson to S-wave Charmonia transition form factors are calculated in next-to-leading order(NLO) accuracy of Quantum Chromodynamics(QCD). Our results indicate that the higher order corrections to these form factors are remarkable, and hence ... More Poincare Inequality on the Path Space of Poisson Point ProcessesJan 17 2008Nov 05 2008The quasi-invariance is proved for the distributions of Poisson point processes under a random shift map on the path space. This leads to a natural Dirichlet form of jump type on the path space. Differently from the O-U Dirichlet form on the Wiener space ... More Single Transverse-Spin Asymmetries at Large-xOct 18 2006The large-$x$ behavior of the transverse-momentum dependent quark distributions is analyzed in the factorization-inspired perturbative QCD framework, particularly for the naive time-reversal-odd quark Sivers function which is responsible for the single ... More On a Lower Bound for the Time Constant of First-Passage PercolationJul 05 2008Jul 13 2008We consider the Bernoulli first-passage percolation on $\mathbb Z^d (d\ge 2)$. That is, the edge passage time is taken independently to be 1 with probability $1-p$ and 0 otherwise. Let ${\mu(p)}$ be the time constant. We prove in this paper that \[ \mu(p_1)-\mu({p_2})\ge ... More Transverse Spin Structure of the NucleonOct 22 2015We review the current status and future perspectives of theory and experiments of transverse spin phenomena in high-energy scattering processes off nucleon targets and related issues in nucleon structure and QCD. Systematic exploration of transverse spin ... More The Influences of Outflow on the Dynamics of InflowMar 21 2008Both numerical simulations and observations indicate that in an advection-dominated accretion flow most of the accretion material supplied at the outer boundary will not reach the inner boundary. Rather, they are lost via outflow. Previously, the influence ... More Fundamental Plane of Black Hole Activity in Quiescent RegimeJan 22 2017A correlation among the radio luminosity ($L_{\rm R}$), X-ray luminosity ($L_{\rm X}$), and black hole mass ($M_{\rm BH}$) in active galactic nuclei (AGNs) and black hole binaries is known to exist and is called the "Fundamental Plane" of black hole activity. ... More On the Threshold Resummation in Forward pA CollisionsJun 09 2018In this paper, using the Higgs production in forward rapidity region in proton-nucleus collisions as an example, we demonstrate that we can construct a systematic formalism for the threshold resummation for forward rapidity particle productions in the ... More χ_{cJ} polarizations at the Fermilab TevatronSep 21 2000Dec 25 2000We propose the measurement of $\chi_{cJ}$ polarizations at high energy hadron colliders to study heavy quarkonium production mechanism. We find that the color-singlet model in the $k_t$ factorization approach predicts very different behavior for $\chi_{cJ}$ ... More On the convective instability of hot radiative accretion flowsJun 10 2010Jun 11 2010How many fraction of gas available at the outer boundary can finally fall onto the black hole is an important question. It determines the observational appearance of accretion flows, and is also related with the evolution of black hole mass and spin. ... More On The Waiting Time for A M/M/1 Queue with ImpatienceApr 06 2017This paper focuses on the problem of modeling the correspondence pattern for ordinary people. Suppose that letters arrive at a rate $\lambda$ and are answered at a rate $\mu$. Furthermore, we assume that, for a constant $T$, a letter is disregarded when ... More Energy Harvesting for Secure OFDMA SystemsSep 12 2014Energy harvesting and physical-layer security in wireless networks are of great significance. In this paper, we study the simultaneous wireless information and power transfer (SWIPT) in downlink orthogonal frequency-division multiple access (OFDMA) systems, ... More Proton Spin Structure at Small-$x$Apr 04 2019We generalize the Bartels-Ermolaev-Ryskin approach for the $g_1$ structure function at small-$x$ to determine the small-$x$ asymptotic behavior of the orbital angular momentum distributions in QCD. We present an exact analytical solution of the evolution ... More The Perfect Distinguishability of Quantum OperationsAug 03 2009We provide a feasible necessary and sufficient condition for when an unknown quantum operation (quantum device) secretely selected from a set of known quantum operations can be identified perfectly within a finite number of queries, and thus complete ... More