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Results for "S. Peng Oh"

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Feedback Heating by Cosmic Rays in Clusters of GalaxiesJun 09 2007Nov 07 2007Recent observations show that the cooling flows in the central regions of galaxy clusters are highly suppressed. Observed AGN-induced cavities/bubbles are a leading candidate for suppressing cooling, usually via some form of mechanical heating. At the ... More
The History and Morphology of Helium ReionizationNov 09 2007Apr 25 2008A variety of observations now indicate that intergalactic helium was fully ionized by z~3. The most recent measurements of the high-redshift quasar luminosity function imply that these sources had produced ~2.5 ionizing photons per helium atom by that ... More
The growth and entrainment of cold gas in a hot windJun 07 2018Jul 24 2018Both absorption and emission line studies show that cold gas around galaxies is commonly outflowing at speeds of several hundred km$\,\textrm{s}^{-1}$. This observational fact poses a severe challenge to our theoretical models of galaxy evolution since ... More
How cold gas continuously entrains mass and momentum from a hot windJul 10 2019The existence of fast moving, cold gas ubiquitously observed in galactic winds is theoretically puzzling, since the destruction time of cold gas is much smaller than its acceleration time. In Gronke & Oh (2018), we showed that cold gas can accelerate ... More
Entropy Injection as a Global Feedback MechanismDec 13 2002Both preheating of the intergalactic medium and radiative cooling of low entropy gas have been proposed to explain the deviation from self-similarity in the cluster L_x-T_x relation and the observed entropy floor in these systems. However, severe overcooling ... More
Could AGN Outbursts Transform Cool Core Clusters?Jul 17 2009Aug 24 2009The origin of the bimodality in cluster core entropy is still unknown. At the same time, recent work has shown that thermal conduction in clusters is likely a time-variable phenomenon. We consider if time-variable conduction and AGN outbursts could be ... More
The Equation of State of the Intergalactic Medium After Hydrogen ReionizationJan 13 2009We use an analytic model to study how inhomogeneous hydrogen reionization affects the temperature distribution of the intergalactic medium (IGM). During this process, the residual energy of each ionizing photon is deposited in the IGM as heat, increasing ... More
Inhomogeneous Helium Reionization and the Equation of State of the Intergalactic MediumNov 05 2007Apr 25 2008The temperature of the intergalactic medium (IGM) is set by the competition between photoheating and adiabatic cooling, which are usually assumed to define a tight equation of state in which the temperature increases monotonically with density. We use ... More
Redshifted 21 Centimeter Emission from Minihalos Before ReionizationApr 04 2006Before reionization, the intergalactic medium (IGM) may have been sufficiently cold for low-mass "minihalos" to condense out of the gas and subsequently affect reionization. Previous work has shown that minihalos generate reasonably large 21 cm fluctuations. ... More
How Universal is the Gunn-Peterson Trough at z~6?: A Closer Look at the Quasar SDSS J1148+5251Nov 05 2004Detectable flux is visible in the Ly-alpha and Ly-beta troughs of the highest redshift ($z=6.42$) quasar found to date, SDSS J1148+5251. This has previously been interpreted as continuum contamination from an interloper galaxy at z=4.94. We examine the ... More
Taxing the Rich: Recombinations and Bubble Growth During ReionizationMay 03 2005Aug 16 2005Reionization is inhomogeneous for two reasons: the clumpiness of the intergalactic medium (IGM) and clustering of the discrete ionizing sources. While numerical simulations can in principle take both into account, they are at present limited by small ... More
Simulations of radiative turbulent mixing layersSep 24 2018May 16 2019Radiative turbulent mixing layers should be ubiquitous in multi-phase gas with shear flow. They are a potentially attractive explanation for the high ions such as OVI seen in high velocity clouds and the circumgalactic medium (CGM) of galaxies. We perform ... More
Giant radio relics in galaxy clusters: reacceleration of fossil relativistic electrons?Jan 23 2013Sep 02 2013Many bright radio relics in the outskirts of galaxy clusters have low inferred Mach numbers, defying expectations from shock acceleration theory and heliospheric observations that the injection efficiency of relativistic particles plummets at low Mach ... More
Cosmic Ray Streaming in Clusters of GalaxiesMar 19 2013The observed bimodality in radio luminosity in galaxy clusters is puzzling. We investigate the possibility that cosmic-ray (CR) streaming in the intra-cluster medium can 'switch off' hadronically induced radio and gamma-ray emission. For self-confined ... More
Cosmology at Low Frequencies: The 21 cm Transition and the High-Redshift UniverseAug 01 2006Sep 20 2006Observations of the high-redshift Universe with the 21 cm hyperfine line of neutral hydrogen promise to open an entirely new window onto the early phases of cosmic structure formation. Here we review the physics of the 21 cm transition, focusing on processes ... More
Reionization Through the Lens of Percolation TheoryNov 04 2015Jan 25 2016The reionization of intergalactic hydrogen has received intense theoretical scrutiny over the past two decades. Here, we approach the process formally as a percolation process and phase transition. Using semi-numeric simulations, we demonstrate that an ... More
Fossil Ionized Bubbles Around Dead Quasars During ReionizationMar 24 2008One of the most dramatic signatures of the reionization era may be the enormous ionized bubbles around luminous quasars (with radii reaching ~40 comoving Mpc), which may survive as "fossil'' ionized regions long after their source shuts off. Here we study ... More
The Effects of Dark Matter Decay and Annihilation on the High-Redshift 21 cm BackgroundAug 17 2006The radiation background produced by the 21 cm spin-flip transition of neutral hydrogen at high redshifts can be a pristine probe of fundamental physics and cosmology. At z~30-300, the intergalactic medium (IGM) is visible in 21 cm absorption against ... More
A Global Stability Analysis of Clusters of Galaxies with Conduction and AGN Feedback HeatingApr 24 2008Aug 07 2008We investigate a series of steady-state models of galaxy clusters, in which the hot intracluster gas is efficiently heated by active galactic nucleus (AGN) feedback and thermal conduction, and in which the mass accretion rates are highly reduced compared ... More
A gravitational lensing explanation for the excess of strong Mg-II absorbers in GRB afterglow spectraApr 12 2010GRB afterglows offer a probe of the intergalactic medium out to high redshift which complements observations along more abundant quasar lines-of-sight. Although both quasars and GRB afterglows should provide a-priori random sight-lines through the intervening ... More
AGN Feedback and Bimodality in Cluster Core EntropyNov 30 2009We investigate a series of steady-state models of galaxy clusters, in which the hot intracluster gas is efficiently heated by active galactic nucleus (AGN) feedback and thermal conduction, and in which the mass accretion rates are highly reduced compared ... More
The impact of magnetic fields on thermal instabilityOct 02 2017Jul 09 2018Cold ($T\sim 10^{4} \ \mathrm{K}$) gas is very commonly found in both galactic and cluster halos. There is no clear consensus on its origin. Such gas could be uplifted from the central galaxy by galactic or AGN winds. Alternatively, it could form in situ ... More
Turbulence and Particle Acceleration in Giant Radio Haloes: the Origin of Seed ElectronsNov 22 2016About 1/3 of X-ray-luminous clusters show smooth, Mpc-scale radio emission, known as giant radio haloes. One promising model for radio haloes is Fermi-II acceleration of seed relativistic electrons by compressible turbulence. The origin of these seed ... More
Turbulence and Particle Acceleration in Giant Radio Halos: the Origin of Seed ElectronsMar 26 2015About 1/3 of X-ray-luminous clusters show smooth, unpolarized radio emission on ~Mpc scales, known as giant radio halos. One promising model for radio halos is Fermi-II acceleration of seed relativistic electrons by turbulence of the intracluster medium ... More
The evolution of the Lyman-alpha forest effective optical depth following HeII reionisationJan 26 2009Apr 16 2009Three independent observational studies have now detected a narrow (\Delta z ~ 0.5) dip centred at z=3.2 in the otherwise smooth redshift evolution of the Lya forest effective optical depth. This feature has previously been interpreted as an indirect ... More
Photo-heating and the fate of hard photons during the reionisation of HeII by quasarsJul 16 2008Mar 16 2009We use a combination of analytic and numerical arguments to consider the impact of quasar photo-heating during HeII reionisation on the thermal evolution of the intergalactic medium (IGM). We demonstrate that rapid (\Delta z< 0.1-0.2), strong (\Delta ... More
Vehicle Energy Dataset (VED), A Large-scale Dataset for Vehicle Energy Consumption ResearchApr 19 2019We present Vehicle Energy Dataset (VED), a novel large-scale dataset of fuel and energy data collected from 383 personal cars in Ann Arbor, Michigan, USA. This open dataset captures GPS trajectories of vehicles along with their time-series data of fuel, ... More
Have We Detected Patchy Reionization in Quasar Spectra?Dec 16 2005The Lyman-alpha forest at z >~ 5.5 shows strong scatter in the mean transmission even when smoothed over very large spatial scales, >~ 50 Mpc/h. This has been interpreted as a signature of strongly fluctuating radiation fields, or patchy reionization. ... More
On the Apparent Power Law in CDM Halo Pseudo Phase Space Density ProfilesJan 05 2017May 19 2017We investigate the apparent power-law scaling of the pseudo phase space density (PPSD) in CDM halos. We study fluid collapse, using the close analogy between the gas entropy and the PPSD in the fluid approximation. Our hydrodynamic calculations allow ... More
The Efficiency of Magnetic Field Amplification at Shocks by TurbulenceMar 28 2016Oct 12 2016Turbulent dynamo field amplification has often been invoked to explain the strong field strengths in thin rims in supernova shocks ($\sim 100 \, \mu$G) and in radio relics in galaxy clusters ($\sim \mu$G). We present high resolution MHD simulations of ... More
Early Cosmological HII/HeIII Regions and Their Impact on Second-Generation Star FormationOct 27 2006Mar 15 2007(Abridged) We present the results of three-dimensional radiation-hydrodynamics simulations of the formation and evolution of early HII/HeIII regions around the first stars. Cooling (by H2 and HD) and recollapse of the gas in the relic HII region is also ... More
The Fermi Bubbles. II. The Potential Roles of Viscosity and Cosmic Ray Diffusion in Jet ModelsOct 04 2011Aug 07 2012The origin of the Fermi bubbles recently detected by the Fermi Gamma-ray Space Telescope in the inner Galaxy is mysterious. In the companion paper Guo & Mathews (Paper I), we use hydrodynamic simulations to show that they could be produced by a recent ... More
From Mirrors to Windows: Lyman-Alpha Radiative Transfer in a Very Clumpy MediumNov 03 2016Lyman-Alpha (Ly$\alpha$) is the strongest emission line in the Universe and is frequently used to detect and study the most distant galaxies. Because Lya is a resonant line, photons typically scatter prior to escaping; this scattering process complicates ... More
Resonant line transfer in a fog: Using Lyman-alpha to probe tiny structures in atomic gasApr 20 2017Motivated by observational and theoretical work which both suggest very small scale ($\lesssim 1\,$pc) structure in the circum-galactic medium of galaxies and in other environments, we study Lyman-$\alpha$ (Ly$\alpha$) radiative transfer in an extremely ... More
Fast Tides in Slow Stars: the Efficiency of Eddy ViscosityJan 03 1997The turbulent viscosity of convection is believed to circularize the orbits of close binary stars. When the tidal period is shorter than the turnover time of the largest eddies, turbulent viscosity is believed to be suppressed. The degree of suppression ... More
A New Numerical Scheme for Cosmic Ray TransportDec 18 2017Numerical solutions of the cosmic-ray (CR) magneto-hydrodynamic equations are dogged by a powerful numerical instability, which arises from the constraint that CRs can only stream down their gradient. The standard cure is to regularize by adding artificial ... More
The Flatness and Sudden Evolution of the Intergalactic Ionizing BackgroundOct 08 2014Oct 01 2015The ionizing background of cosmic hydrogen is an important probe of the sources and absorbers of ionizing radiation in the post-reionization universe. Previous studies show that the ionization rate should be very sensitive to changes in the source population: ... More
Constraining Very High Mass Population III Stars through He II Emission in Galaxy BDF-521 at z = 7.01Dec 11 2014Numerous theoretical models have long proposed that a strong He II 1640 emission line is the most prominent and unique feature of massive Population III (Pop III) stars in high redshift galaxies. The He II 1640 line strength can constrain the mass and ... More
Model Atmospheres for Irradiated Giant Stars: Implications for the Galactic CenterJan 24 2006Jan 27 2006Irradiation of a stellar atmosphere by an external source (e.g. an AGN) changes its structure and therefore its spectrum. Using a state-of-the-art stellar atmosphere code, we calculate the infrared spectra of such irradiated and transformed stars. We ... More
The Distribution of Bubble Sizes During ReionizationNov 04 2015Oct 06 2016A key physical quantity during reionization is the size of HII regions. Previous studies found a characteristic bubble size which increases rapidly during reionization, with apparent agreement between simulations and analytic excursion set theory. Using ... More
Implementation of Frequency-Severity Association in BMS RatemakingMar 14 2019A Bonus-Malus System (BMS) in insurance is a premium adjustment mechanism widely used in a posteriori ratemaking process to set the premium for the next contract period based on a policyholder's claim history. The current practice in BMS implementation ... More
Intensity Mapping with Carbon Monoxide Emission Lines and the Redshifted 21 cm LineApr 25 2011We quantify the prospects for using emission lines from rotational transitions of the CO molecule to perform an `intensity mapping' observation at high redshift during the Epoch of Reionization (EoR). The aim of CO intensity mapping is to observe the ... More
Plasma 2020 - Intracluster Medium PlasmasMar 20 2019Galaxy clusters are the largest and most massive bound objects resulting from cosmic hierarchical structure formation. Baryons account for somewhat more than 10% of that mass, with roughly 90% of the baryonic matter distributed throughout the clusters ... More
Probing Population III Stars in Galaxy IOK-1 at z = 6.96 through He II EmissionMay 11 2011Jul 08 2011The He II \lambda 1640 emission line has been suggested as a direct probe of Population III (Pop III) stars at high-redshift, since it can arise from highly energetic ionizing photons associated with hot, metal free stars. We use the HST WFC3/F130N IR ... More
Spontaneous CP violation in the triplet extended supersymmetric standard modelDec 08 2008We find that, at the one-loop level, the spontaneous CP violation is possible in a supersymmetric standard model that has an extra chiral Higgs triplet with hypercharge Y=0. At the tree level, this triplet-extended supersymmetric standard model (TESSM) ... More
Phase-dependent spectra in a driven two-level atomDec 23 1998We propose a method to observe phase-dependent spectra in resonance fluorescence, employing a two-level atom driven by a strong coherent field and a weak, amplitude-fluctuating field. The spectra are similar to those which occur in a squeezed vacuum, ... More
Optimal squeezing, pure states, and amplification of squeezing in resonance fluorescenceDec 30 1998It is shown that 100% squeezed output can be produced in the resonance fluorescence from a coherently driven two-level atom interacting with a squeezed vacuum. This is only possible for $N=1/8$ squeezed input, and is associated with a pure atomic state, ... More
Probing Bayesian credible regions intrinsically: a feasible error certification for physical systemsFeb 07 2019Computing size and credibility of Bayesian credible regions for certifying the reliability of any point estimator of an unknown parameter (such as a quantum state, channel, phase, \emph{etc.}) relies on rejection sampling from the entire parameter space ... More
Efficient Bayesian credible-region certification for quantum-state tomographyFeb 07 2019Jun 27 2019Standard Bayesian credible-region theory for constructing an error region on the unique estimator of an unknown state in general quantum-state tomography to calculate its size and credibility relies on heavy Monte~Carlo sampling of the state space followed ... More
One-loop corrections to omega photoproduction near thresholdApr 15 2002Aug 21 2002One-loop corrections to $\omega$ photoproduction near threshold have been investigated by using the approximation that all relevant transition amplitudes are calculated from the tree diagrams of effective Lagrangians. With the parameters constrained by ... More
Final state interactions in omega photoproduction near thresholdJan 08 2002Vector meson photoproduction and electroproduction have been suggested as a tool to find or confirm the nucleon resonances. In order to extract more reliable informations on the nucleon resonances, understanding the non-resonant background is indispensable. ... More
Probing Bayesian credible regions intrinsically: a feasible error certification for physical systemsFeb 07 2019Jun 27 2019Computing size and credibility of Bayesian credible regions for certifying the reliability of any point estimator of an unknown parameter (such as a quantum state, channel, phase, \emph{etc.}) relies on rejection sampling from the entire parameter space ... More
Rho meson photoproduction at low energiesJun 10 2003Nov 21 2003The $\sigma$-exchange and $f_2$-exchange mechanisms for $\rho$ meson photoproduction are re-examined. Then the commonly employed $\sigma$-exchange amplitude is revised by using the recent information from the analyses on the $\rho \to \pi^0\pi^0\gamma$ ... More
f_2, sigma, and 2-pi exchanges in rho meson photoproductionAug 04 2003The $\sigma$ meson exchange model for $\rho$ photoproduction at low energies is re-examined and a new model is developed by considering explicit two-pion exchange and the $f_2$ tensor meson exchange. The $f_2$ exchange model, which is motivated by the ... More
pi and rho loop corrections to omega photoproduction in the resonance regionNov 19 2002One-loop corrections due to the intermediate $\pi N$ and $\rho N$ states are studied in $\omega$ photoproduction near threshold. Our results show that the coupled-channel effects should be taken into account in extracting reliable nucleon resonance parameters ... More
Efficient Bayesian credible-region certification for quantum-state tomographyFeb 07 2019Standard Bayesian credible-region theory for constructing an error region on the unique estimator of an unknown state in general quantum-state tomography to calculate its size and credibility relies on heavy Monte~Carlo sampling of the state space followed ... More
Josephson effects in MgB2 meta masked ion damage junctionsJun 12 2002Ion beam damage combined with nanoscale focused ion beam direct milling was used to create manufacturable SNS type Josephson junctions in 100 nm thick MgB$_{2}$ with T$_{C}$ of 38 K. The junctions show non-hysteretic current - voltage characteristics ... More
Semantic Instance Segmentation via Deep Metric LearningMar 30 2017We propose a new method for semantic instance segmentation, by first computing how likely two pixels are to belong to the same object, and then by grouping similar pixels together. Our similarity metric is based on a deep, fully convolutional embedding ... More
Electroweak phase transition in an extension of the standard model with a real Higgs singletNov 27 2004May 25 2005The Higgs potential of the standard model with an additional real Higgs singlet is studied in order to examine if it may allow the strongly first order electroweak phase transition. It is found that there are parameter values for which this model at the ... More
Radiative CP violation in the Higgs sector of the Next-to-minimal supersymmetric modelAug 26 2003Oct 20 2003We investigate the neutral Higgs sector in the next-to-minimal supersymmetric standard model (NMSSM) with explicit CP violation at the one-loop level by using the effective potential method. In general, explicit CP violation is possible at the tree-level ... More
Spontaneous Violation of the CP Symmetry in the Higgs Sector of the Next-to-Minimal Supersymmetric ModelOct 24 1999The spontaneous violation of the CP symmetry in the next-to-minimal supersymmetric standard Model (NMSSM) is investigated. It is found that the spontaneous violation of the CP symmetry can occur in the Higgs sector of the NMSSM for a wide region of the ... More
Lyman Alpha Radiative Transfer in a Multi-Phase MediumJul 25 2005Hydrogen Ly-alpha is our primary emission-line window into high redshift galaxies. Surprisingly, despite an extensive literature, Ly-alpha radiative transfer in the most realistic case of a dusty, multi-phase medium has not received detailed theoretical ... More
Systematic Effects of Foreground Removal in 21cm Surveys of ReionizationOct 20 2010Mar 16 2011It is well-known that foreground subtraction in 21cm surveys removes large scale power. We investigate associated systematic biases. We show that removing line-of-sight fluctuations on large scales aliases into suppression of the 3D power spectrum across ... More
Quasar Feedback: the Missing Link in Structure FormationJan 07 2004Feb 19 2004We consider the impact of quasar outflows on structure formation. Such outflows are potentially more important than galactic winds, which appear insufficient to produce the level of preheating inferred from X-ray observations of galaxy clusters. Using ... More
Disentangling Resonant Scattering and Gas Motions in Galaxy Cluster Emission Line ProfilesNov 11 2012Nov 28 2012Future high spectral resolution telescopes will enable us to place tight constraints on turbulence in the intra-cluster medium through the line widths of strong emission lines. At the same time, these bright lines are the most prone to be optically thick. ... More
Shaken and stirred: conduction and turbulence in clusters of galaxiesNov 27 2009Dec 16 2009(abridged) Uninhibited radiative cooling in clusters of galaxies would lead to excessive mass accretion rates contrary to observations. One of the key proposals to offset radiative energy losses is thermal conduction from outer, hotter layers of cool ... More
Probing Gas Motions in the Intra-Cluster Medium: A Mixture Model ApproachApr 26 2012Upcoming high spectral resolution telescopes, particularly Astro-H, are expected to finally deliver firm quantitative constraints on turbulence in the intra-cluster medium (ICM). We develop a new spectral analysis technique which exploits not just the ... More
A generalization of the Cai--Galloway splitting theorem to smooth metric measure spacesJul 02 2013We generalize the splitting theorem of Cai-Galloway for complete Riemannian manifolds with $\Ric\geq-(n-1)$ admitting a family of compact hypersurfaces tending to infinity with mean curvatures tending to $n-1$ sufficiently fast to the setting of smooth ... More
Neutral scalar Higgs bosons in the USSM at the LHCJan 15 2008Jul 18 2008We study the possibility of discovering neutral scalar Higgs bosons in the $U(1)'$-extended supersymmetric standard model (USSM) at the CERN Large Hadron Collider (LHC), by examining their productions via the exotic quark loop in the gluon fusion process ... More
Anomalous percolation transitions beyond the BKT transition in growing networksMay 11 2018Aug 14 2018Since the discovery a half century ago that 1/r^2-type long-range interactions in the one-dimensional Ising model change the phase transition type, long-range interactions in diverse systems have received considerable attention. Recently, this interest ... More
Study of Higgs self couplings of a supersymmetric $E_6$ model at the International Linear ColliderNov 30 2009We study the Higgs self couplings of a supersymmetric $E_6$ model that has two Higgs doublets and two Higgs singlets. The lightest scalar Higgs boson in the model may be heavier than 112 GeV, at the one-loop level, where the negative results for the Higgs ... More
On global $L^q$ estimates for systems with $p$-growth in rough domainsOct 22 2018We study regularity results for nonlinear parabolic systems of $p$-Laplacian type with inhomogeneous boundary and initial data, with $p\in(\frac{2n}{n+2},\infty)$. We show bounds on the gradient of solutions in the Lebesgue-spaces with arbitrary large ... More
Uniqueness and traveling waves in a cell motility modelMar 02 2017We study a non-linear and non-local evolution equation for curves obtained as the sharp interface limit of a phase-field model for crawling motion of eukaryotic cells on a substrate. We establish uniqueness of solutions to the sharp interface limit equation ... More
Double Poisson extensionsJun 08 2016Jul 05 2016A double Ore extension was introduced by James Zhang and Jun Zhang \cite{ZhZh} to study Artin-Schelter regular algebras. Here, we give a definition of double Poisson extension which may be considered as a Poisson analogue of double Ore extension and show ... More
The effect of time-varying flow-shear on the nonlinear stability of the boundary of magnetized toroidal plasmasAug 14 2017Sep 23 2017We propose a phenomenological yet very general model in a form of generalized complex Ginzburg-Landau equation to understand the dynamics of the quasi-periodic fluid instabilities (called edge-localized modes) in the boundary of toroidal magnetized high-temperature ... More
Double Poisson extensionsJun 08 2016Jun 07 2018A double Ore extension was introduced by James Zhang and Jun Zhang [26] to study a class of Artin-Schelter regular algebras. Here we give a definition of Poisson double extension which may be considered as an analogue of double Ore extension and show ... More
Current and noise expressions for radio-frequency single-electron transistorsMar 04 2005We derive self-consistent expressions of current and noise for single-electron transistors driven by time-dependent perturbations. We take into account effects of the electrical environment, higher-order co-tunneling, and time-dependent perturbations ... More
Abelian Decomposition of General RelativityFeb 17 2011Based on the view that Einstein's theory can be interpreted as a gauge theory of Lorentz group, we decompose the gravitational connection (the gauge potential of Lorentz group) $\vGm_\mu$ into the restricted connection made of the potential of the maximal ... More
Higher dimensional cosmological model with a phantom fieldJan 24 2008May 21 2008We consider a higher dimensional gravity theory with a negative kinetic energy scalar field and a cosmological constant. We find that the theory admits an exact cosmological solution for the scale factor of our universe. It has the feature that the universe ... More
Nucleon resonances in omega photoproductionJun 25 2000Nov 13 2000The role of the nucleon resonances ($N^*$) in $\omega$ photoproduction is investigated by using the resonance parameters predicted by Capstick and Roberts [Phys. Rev. D {\bf 46}, 2864 (1992); {\bf 49}, 4570 (1994)]. In contrast with the previous investigations ... More
Nuclear Magnetic Resonance Studies of Vortices in High Temperature SuperconductorsDec 15 2011The distinct distribution of local magnetic fields due to superconducting vortices can be detected with nuclear magnetic resonance (NMR) and used to investigate vortices and related physical properties of extreme type II superconductivity. This review ... More
Mathematical analysis of long-time behavior of magnetized fluid instabilities with shear flowJun 25 2017We study a complex Ginzburg-Landau (GL) type model related to fluid instabilities in the boundary of magnetized toroidal plasmas (called edge-localized modes) with a prescribed shear flow on the Neumann boundary condition. We obtain the following universal ... More
Time-dependent Currents of a Single-electron Transistor in Dissipative EnvironmentsSep 30 2003Currents of the single-electron transistors driven by time-dependent fields via external dissipative circuits are investigated theoretically. By expressing the external circuit in terms of driven harmonic oscillators and using the reduced-density operator ... More
Optically Driven Qubits in Artificial MoleculesMay 16 2000May 17 2000We present novel models of quantum gates based on coupled quantum dots in which a qubit is regarded as the superposition of ground states in each dot. Coherent control on the qubit is performed by both a frequency and a polarization of a monochromatic ... More
Photo-excitation of hyperons and exotic baryon in gamma N --> K Anti-K NNov 16 2005Nov 17 2005We investigate the reaction of $\gamma N \to K \bar{K} N$ focusing on the photoproduction of $\Lambda(1520)$ and putative exotic $\Theta(1540)$. We consider various background production mechanisms including the production of vector mesons, tensor mesons, ... More
Nucleon resonances in polarized omega photoproductionDec 05 2000The role of the nucleon resonances ($N^*$) in $\omega$ photoproduction is investigated by using the resonance parameters predicted by Capstick and Roberts. The contributions from the nucleon resonances are found to be significant in various spin asymmetries. ... More
Electromagnetic production of vector mesons at low energiesApr 25 2000We have investigated exclusive photoproduction of light vector mesons ($\omega$, $\rho$ and $\phi$) on the nucleon at low energies. In order to explore the questions concerning the so-called missing nucleon resonances, we first establish the predictions ... More
Medium Effects in rho-Meson PhotoproductionDec 04 2008Apr 09 2009We compute dilepton invariant mass spectra from the decays of rho mesons produced by photon reactions off nuclei. Our calculations employ a realistic model for the rho photoproduction amplitude on the nucleon which provides fair agreement with measured ... More
Cavity induced modifications to the resonance fluorescence and probe absorption of a laser-dressed V atomMar 20 2000A cavity-modified master equation is derived for a coherently driven, V-type three-level atom coupled to a single-mode cavity in the bad cavity limit. We show that population inversion in both the bare and dressed-state bases may be achieved, originating ... More
Recent Neutrino Data and Type III Seesaw with Discrete SymmetryMar 03 2011Jun 21 2012In light of the recent neutrino experiment results from Daya Bay and RENO Collaborations, we study phenomenology of neutrino mixing angles in the Type III seesaw model with an discrete $A_4 \times Z_2$ symmetry, whose spontaneously breaking scale is much ... More
Medium Modifications of the Rho Meson in Nuclear PhotoproductionMar 04 2010Jul 18 2010We extend our recent study of dilepton invariant-mass spectra from the decays of rho mesons produced by photon reactions off nuclei. We specifically focus on experimental spectra as recently measured by the CLAS Collaboration at the Thomas Jefferson National ... More
Pentaquark Theta^+(1540) production in gamma N --> K Anti-K NDec 23 2004Oct 20 2005The recent developments in the search of exotic pentaquark hadrons are briefly reviewed. We then focus on investigating how the exotic pentaquark $\Theta(1540)$ baryon production can be identified in the $\gamma N \to K \bar{K} N$ reactions, focusing ... More
Time-convolutionless reduced-density-operator theory of a noisy quantum channel: a two-bit quantum gate for quantum information processingJul 23 1999An exact reduced-density-operator for the output quantum states in time-convolutionless form was derived by solving the quantum Liouville equation which governs the dynamics of a noisy quantum channel by using a projection operator method and both advanced ... More
Deep Virtual Networks for Memory Efficient Inference of Multiple TasksApr 09 2019Deep networks consume a large amount of memory by their nature. A natural question arises can we reduce that memory requirement whilst maintaining performance. In particular, in this work we address the problem of memory efficient learning for multiple ... More
Extracting the CKM phase angle γ(\equiv φ_3) from isospin analysis in B\to K πdecaysOct 08 2007Dec 15 2008We propose a new method to extract the CKM phase angle \gamma (\equiv \phi_3) from the isospin analysis in B \to K \pi decays. Unlike previously proposed methods, we do not employ flavor SU(3) symmetry, so that this method is free from the hadronic uncertainty ... More
CP Asymmetries of $B \to φK$ and $B \to η^{(\prime)} K$ Decays Using a Global Fit in QCD FactorizationDec 31 2003Jan 03 2004We analyze the CP asymmetries of $B\to \phi K$ and $B\to \eta^{(\prime)} K$ modes in the QCD improved factorization framework. For our calculation we use the phenomenological parameters predetermined from the global fit for the available $B\to PP$ and ... More
An Analysis of $B \to η' K$ Decays Using a Global Fit in QCD FactorizationDec 31 2003Jan 03 2004In the framework of QCD factorization, we study $B^{+(0)} \to \eta' K^{+(0)}$ decays. In order to more reliably determine the phenomenological parameters $X_H$ and $X_A$ arising from end-point divergences in the hard spectator scattering and weak annihilation ... More
Quasi-invariant Gaussian measures for the nonlinear wave equation in three dimensionsAug 09 2018Nov 27 2018We prove quasi-invariance of Gaussian measures supported on Sobolev spaces under the dynamics of the three-dimensional defocusing cubic nonlinear wave equation. As in the previous work on the two-dimensional case, we employ a simultaneous renormalization ... More
Optomechanical Measurement of the Abraham Force in an Adiabatic Liquid Core Optical Fiber WaveguideJan 20 2016We report quantitative experimental measurements of the Abraham force associated with a propagating optical wave. We isolate this force using a guided light wave undergoing an adiabatic mode transformation (AMT) along a liquid-filled hollow optical fiber ... More
Analytic Resolution of Puzzle in $B\to K π$ decaysJul 19 2007Jul 11 2008We present a systematic method to extract each standard model (SM)-{\it like} hadronic parameter as well as new physics parameters in analytic way for $B\to K\pi$ decays. Using the analytic method to the currently available experimental data, we find ... More