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D. F. Wang

Publications and source records attributed to D. F. Wang.

At least 19 recordsLinked to original sources
arXiv2021

System size dependence of baryon-strangeness correlations in relativistic heavy ion collisions from a multiphase transport model

The system size dependence of baryon-strangeness (BS) correlations ($C_{BS}$) are investigated with a multiphase transport (AMPT) model for various collision systems from $\mathrm{^{10}B+^{10}B}$, $\mathrm{^{12}C+^{12}C}$, $\mathrm{^{16}O+^{16}O}$, $\mathrm{^{20}Ne+^{20}Ne}$, $\mathrm{^{40}Ca+^{40}Ca}$, $\mathrm{^{96}Zr+^{96}Zr}$, and $\mathrm{^{197}Au+^{197}Au}$ at RHIC energies $\sqrt{s_{NN}}$ of 200, 39, 27, 20, and 7.7 GeV. Both effects of hadron rescattering and a combination of different hadrons play a leading role for baryon-strangeness correlations. When the kinetic window is limited to absolute rapidity $|y|>3$, these correlations tend to be constant after the final-state interaction whatever kind of hadrons subset we chose based on the AMPT framework. The correlation is found to smoothly increase with baryon chemical potential $μ_B$, corresponding to the collision system or energy from the quark-gluon-plasma-like phase to the hadron-gas-like phase. Besides, the influence of initial nuclear geometrical structures of $α$-clustered nuclear collision systems of $\mathrm{^{12}C+^{12}C}$ as well as $\mathrm{^{16}O+^{16}O}$ collisions is discussed but the effect is found negligible. The current model studies provide baselines for searching for the signals of Quantum Chromodynamics (QCD) phase transition and critical point in heavy-ion collisions through the BS correlation.

hep-ph↗
arXiv1999

Spread option and exchange option with stochastic interest rates

In this work, we consider the issue of pricing exchange options and spread options with stochastic interest rates. We provide the closed form solution for the exchange option price when interest rate is stochastic. Our result holds when interest rate is modeled with a stochastic term structure of general form, which includes Vasicek model, CIR term structure, and other well-known term structure models as special cases. In particular, we have discussed the possibility of using our closed form solution as a control variate in pricing spread options with stochastic interest rate.

cond-mat↗
arXiv1998

Generalizing Merton's approach of pricing risky debt: some closed form results

In this work, I generalize Merton's approach of pricing risky debt to the case where the interest rate risk is modeled by the CIR term structure. Closed form result for pricing the debt is given for the case where the firm value has non-zero correlation with the interest rate. This extends previous closed form pricing formular of zero-correlation case to the generic one of non-zero correlation between the firm value and the interest rate.

cond-mat.stat-mech↗
arXiv1998

Pricing defaultable debt: some exact results

In this letter, I consider the issue of pricing risky debt by following Merton's approach. I generalize Merton's results to the case where the interest rate is modeled by the CIR term structure. Exact closed forms are provided for the risky debt's price.

cond-mat.stat-mech↗
arXiv1998

Hedging The Risk In The Continuous Time Option Pricing Model With Stochastic Stock Volatility

In this work, I address the issue of forming riskless hedge in the continuous time option pricing model with stochastic stock volatility. I show that it is essential to verify whether the replicating portfolio is self-financing, in order for the theory to be self-consistent. The replicating methods in existing finance literature are shown to violate the self-financing constraint when the underlying asset has stochastic volatility. Correct self-financing hedge is formed in this article.

cond-mat.stat-mech↗
arXiv1998

Revisiting the Black-Scholes equation

In common finance literature, Black-Scholes partial differential equation of option pricing is usually derived with no-arbitrage principle. Considering an asset market, Merton applied the Hamilton-Jacobi-Bellman techniques of his continuous-time consumption-portfolio problem, deriving general equilibrium relationships among the securities in the asset market. In special case where the interest rate is constant, he rederived the Black-Scholes partial differential equation from the general equilibrium asset market. In this work, I follow Cox-Ingersoll-Ross formulation to consider an economy which includes (1) uncertain production processes, and (2) the random technology change. Assuming a random production stochastic process of constant drift and variance, and assuming a random technology change to follow a log normal process, the equilibrium point of this economy will lead to the Black-Scholes partial differential equation for option pricing.

cond-mat.stat-mech↗
arXiv1997

Parity-locking effect in a strongly-correlated ring

Orbital magnetism in an integrable model of a multichannel ring with long-ranged electron-electron interactions is investigated. In a noninteracting multichannel system, the response to an external magnetic flux is the sum of many diamagnetic and paramagnetic contributions, but we find that for sufficiently strong correlations, the contributions of all channels add constructively, leading to a parity (diamagnetic or paramagnetic) which depends only on the total number of electrons. Numerical results confirm that this parity-locking effect is robust with respect to subband mixing due to disorder.

cond-mat.str-el↗
arXiv1997

Interaction-Induced Enhancement and Oscillations of the Persistent Current

The persistent current $I$ in integrable models of multichannel rings with both short- and long-ranged interactions is investigated. $I$ is found to oscillate in sign and increase in magnitude with increasing interaction strength due to interaction-induced correlations in the currents contributed by different channels. For sufficiently strong interactions, the contributions of all channels are found to add constructively, leading to a giant enhancement of $I$. Numerical results confirm that this parity-locking effect is robust with respect to subband mixing due to disorder.

cond-mat.mes-hall↗
arXiv1996

Integrabilities of the long range t-J model of twisted boundary condition

The integrability of the one-dimensional long range supersymmetric t-J model has previously been established for both open systems and those closed by periodic boundary conditions through explicit construction of its integrals of motion. Recently the system has been extended to include the effect of magnetic flux, which gives rise to a closed chain with twisted boundary conditions. While the t-J model with twisted boundary conditions has been solved for the ground state and full energy spectrum, proof of its integrability has so far been lacking. In this letter we extend the proof of integrability of the long range supersymmetric t-J model and its SU(m|n) generalization to include the case of twisted boundary conditions.

solv-int↗
arXiv1996

The 1/r2 t-J model in a magnetic field

We study the one-dimensional supersymmetric t-J model with 1/r2 interaction threaded by magnetic flux. Because of the long range interaction, the effect of this flux leads to a modification of the electron hopping term. We present an exact solution of this model for all values of the flux, concisely formulated as a set of Bethe-ansatz-like equations. This allows a computation of the persistent currents at zero temperature. It is found that the system violates Leggett's conjecture despite the fact that the long range t-J model is a special example of the Luttinger liquid university class.

cond-mat↗
arXiv1996

SU(m|n) supersymmetric Calogero-Sutherland model confined in harmonic potential

In this work, we study a continuous quantum system of a mixture of bosons and fermions with the supersymmetry SU(m|n). The particles are confined in a harmonic well and interact with each other through the 1/r2 interaction. The ground state wavefunction is constructed explicitly for the most general SU(m|n) case, with the ground state energy given explicitly. The full energy spectrum of excitations in the SU(m|n) model is also equal spaced. In the limiting case where there are no bosons in the system, our results reduce to those obtained previously.

cond-mat↗
arXiv1996

Ferromagnetism in an itinerant electron system: Hubbard model on complete graph

In this work, the ground states of the Hubbard model on complete graph are studied, for a finite lattice size $L$ and arbitrary on-site energy $U$. We construct explicitly the ground states of the system when the number of the electrons $N_e \ge L+1$. In particular, for $N_e=L+1$, the ground state is ferromagnetic with total spin $s_g=(N_e-2)/2$.

cond-mat↗
arXiv1996

A remark on off-diagonal long range order

In this work, we study some general property of a strongly correlated electron system defined on a lattice. Assuming that the lattice system exhibits off-diagonal long range order, we show rigorously that this assumption would lead to Meissner effect. This generalizes previous results of continuous case to a lattice electron system.

cond-mat↗
arXiv1996

Exactly solvable multi-channel Kondo lattice model

In this work, a multichannel Kondo lattice model is studied in the thermodynamic limit. The conduction band is described by a constant hopping amplitude between any pair of lattice sites. For this system, we have obtained the exact thermodynamical properties and the ground state energies. In the limit of strong interaction between the electrons and the impurity spins, the wavefunctions take the Jastrow product form.

cond-mat↗
arXiv1996

Integrable SU(m|n) supersymmetric electronic models of strong correlations

We generalize the SU(2|2) supersymmetric extended Hubbard model of 1/r2 interaction to the SU(m|n) supersymmetric case. Integrable models may be defined on both uniform lattice and non-uniform one dimensional lattices. We study both cases in detail and present the ground state wavefunctions and energy spectra of these models.

cond-mat↗
arXiv1996

Ground state and excitations of the extended Hubbard model

We examine the ground state and excitations of the one dimensional extended Hubbard model with long range interaction. The ground state wavefunctions and low lying excitations are given explicitly in the form of a Jastrow product of two body terms. This results motivates an asymptotic Bethe-ansatz for the model. We present evidence that this solution is in fact exact and spans the complete spectrum of states.

cond-mat↗
arXiv1995

On chiral Hubbard model at strong interaction

One dimensional chiral Hubbard model reduces to the Haldane-Shastry spin chain at half-filling with large but finite on-site energy $U$.In this talk, we show that the Gutzwiller-Jastrow wavefunctions are the eigen-states of the Hubbard model at $U=+\infty$ at less than half-filling. The full energy spectrum and an infinite set of mutually commuting constants of motion are also given in this limit for the system.

cond-mat↗