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Articles 1 - 9 of 9
Full-Text Articles in Physical Sciences and Mathematics
Worm Algorithms For Classical Statistical Models, Nikolai Prokof'ev, Boris Svistunov
Worm Algorithms For Classical Statistical Models, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
We show that high-temperature expansions provide a basis for the novel approach to efficient Monte Carlo simulations. “Worm” algorithms utilize the idea of updating closed-path configurations (produced by high-temperature expansions) through the motion of end points of a disconnected path. An amazing result is that local, Metropolis-type schemes using this approach appear to have dynamical critical exponents close to zero (i.e., their efficiency is comparable to the best cluster methods) as proved by finite-size scaling of the autocorrelation time for various universality classes.
Single-Hole Spectral Function And Spin-Charge Separation In The T-J Model, A Mishchenko, Nikolai Prokof'ev, Boris Svistunov
Single-Hole Spectral Function And Spin-Charge Separation In The T-J Model, A Mishchenko, Nikolai Prokof'ev, Boris Svistunov
Physics Department Faculty Publication Series
Worm algorithm Monte Carlo simulations of the hole Green function with subsequent spectral analysis were performed for 0.1<~J/t<~0.4 on lattices with up to L×L=32×32 sites at a temperature as low as T=J/40, and present, apparently, the hole spectral function in the thermodynamic limit. Spectral analysis reveals a δ-function-sharp quasiparticle peak at the lower edge of the spectrum that is incompatible with the power-law singularity and thus rules out the possibility of spin-charge separation in this parameter range. Spectral continuum features two peaks separated by a gap ∼4÷5 t.
Calibrations And Fayyazuddin-Smith Spacetimes, Hyunji Cho, Moataz Emam, David Kastor, Jennie Traschen
Calibrations And Fayyazuddin-Smith Spacetimes, Hyunji Cho, Moataz Emam, David Kastor, Jennie Traschen
Physics Department Faculty Publication Series
We show that a class of spacetimes introduced by Fayyazuddin and Smith to describe intersecting M5-branes admits a generalized Kähler calibration. Equipped with this understanding, we are able to construct spacetimes corresponding to further classes of calibrated p-brane world-volume solitons. We note that these classes of spacetimes also describe the fields of p-branes wrapping certain supersymmetric cycles of Calabi-Yau manifolds.
Chiral Symmetry And The Parity-Violating Nn Pi Yukawa Coupling, Sl Zhu, Sj Puglia, Br Holstein, Mj Ramsey-Musolf
Chiral Symmetry And The Parity-Violating Nn Pi Yukawa Coupling, Sl Zhu, Sj Puglia, Br Holstein, Mj Ramsey-Musolf
Physics Department Faculty Publication Series
We construct the complete SU(2) parity-violating (PV) π,N,Δ interaction Lagrangian with one derivative, and calculate the chiral corrections to the PV Yukawa NNπ coupling constant hπ through O(1/Λχ3) in the leading order of heavy baryon expansion. We discuss the relationship between the renormalized hπ, the measured value of hπ, and the corresponding quantity calculated microscopically from the standard model four-quark PV interaction. We observe that the renormalized hπ depends strongly on a number of a priori unknown parameters in the PV effective Lagrangian.
Random Values Of The Physical Parameters, Jf Donoghue
Random Values Of The Physical Parameters, Jf Donoghue
Physics Department Faculty Publication Series
I briefly describe two motivations, two mechanisms and two possible tests of the hypothesis that the physical parameters of the ground state of a theory can vary in different rerions of the universe.
New Insights Concerning Dimension Eight Effects In Weak Decays, Jf Donoghue
New Insights Concerning Dimension Eight Effects In Weak Decays, Jf Donoghue
Physics Department Faculty Publication Series
Most past work on weak nonleptonic decays has mixed dimensional regularization in the weak operator product expansion with some form of a cutoff regularization in the evaluation of the matrix elements. Even with the usual technique of matching the two schemes, this combination misses physics at short distance which can be described by dimension eight (and higher dimension) operators. I describe some recent work with V. Cirigliano and E. Golowich which clarifies these effects and provides a numerical estimate suggesting that they are important.
Effective Interactions Are Effective Interactions, Br Holstein
Effective Interactions Are Effective Interactions, Br Holstein
Physics Department Faculty Publication Series
In recent years it has been realized that effective interactions—those valid over a limited range of energy-momentum—are often preferable even when more complete theories are available. We shall here present examples of such methods over a range of physical applications—from classical and quantum mechanics, to quantum gravity.
The Influence Of Dimension Eight Operators On Weak Matrix Elements, Jf Donoghue
The Influence Of Dimension Eight Operators On Weak Matrix Elements, Jf Donoghue
Physics Department Faculty Publication Series
I describe recent work with V. Cirigliano and E. Golowich on the effect of dimension eight operators on weak nonleptonic amplitudes. The basic mesage is that there is an inconsistency in the way that many calculations are traditionally performed. If one calculates matrix elements involving only physics below some scale μ, then one needs dimension eight operators explicitly in the weak OPE. On the other hand if one wants to use dimensional regularization throughout, then one needs all scales to be included within the matrix element, and this results in the same net effect. A numerical estimate indicates that this …
Critical Point Of A Weakly Interacting Two-Dimensional Bose Gas, N Prokof'ev, O Ruebenacker, B Svistunov
Critical Point Of A Weakly Interacting Two-Dimensional Bose Gas, N Prokof'ev, O Ruebenacker, B Svistunov
Physics Department Faculty Publication Series
We study the Berezinskii-Kosterlitz-Thouless transition in a weakly interacting 2D quantum Bose gas using the concept of universality and numerical simulations of the classical |ψ|4 model on a lattice. The critical density and chemical potential are given by relations nc = (mT/2πħ2)ln(ξħ2/mU) and μc = (mTU/πħ2)ln(ξμħ2/mU), where T is the temperature, m is the mass, and U is the effective interaction. The dimensionless constant ξ = 380±3 is very large and thus any quantitative analysis of the experimental data crucially depends on its value. For ξμ our result is ξμ = 13.2±0.4. We also report the study of the quasicondensate …