57,625 research outputs found
Progress in FDC Project
The FDC is a general-purpose program package for Feynman Diagram Calculation.
We outline previous successes in calculations and focus on its recent progress
about automatic deduction the Feynman rules for first principle model,
especially for the supersymmetric model, proper evaluation of the rates of
multi-final-particle processes and the event generators in the SM and MSSM. A
few special applications are presented. The FDC-homepage shows an automatic
translation of the FDC results into the HTTP version.Comment: Presented at 9th International Workshop on Advanced Computing and
Analysis Techniques in Physics Research (ACAT 03), Tsukuba, Japan, 1-5 Dec
200
Electron-electron interactions, quantum Coulomb gap, and dynamical scaling near integer quantum Hall transitions
The effects of electron-electron interactions on the bulk tunneling density
of states (TDOS) are studied near the integer quantum Hall transitions (IQHT).
Taking into account the dynamical screening of the interactions in the critical
conducting state, we show that the behavior of the TDOS is significantly
altered from its noninteracting counterpart. For Coulomb interaction, we
demonstrate that the TDOS vanishes linearly at the Fermi level according to a
quantum Coulomb gap form with a nonuniversal slope. For short-range
interactions, the TDOS is found to follow a power-law with an exponent
proportional to the interaction strength. Since short-range interactions are
known to be irrelevant perturbations at the non-interacting critical point, we
predict that upon scaling, the power-law is smeared, leading to a finite zero
bias TDOS. However, the approach to the zero-bias value is described by a
power-law with a universal exponent determined by the scaling dimension of
short-range interactions. We also consider the case of quasi-1D samples with
edges and find that the TDOS becomes dependent of the Hall conductance due to
an altered boundary condition for diffusion. For short-range interactions, the
TDOS of a quasi-1D strip is linear near the Fermi level with a slope inversely
proportional to the resistivity in the perturbative limit. These results are in
qualitative agreement with the bulk tunneling experiments. We discuss recent
developments in understanding the role played by electron-electron interactions
at the IQHT and the implications of these results on dynamical scaling of the
transition width. We argue that for the long-range Coulomb interaction, the
existence of the quantum Coulomb gap in the quantum critical regime of the
transition gives rise to the observed dynamical exponent z=1.Comment: 33 pages, 6 figures, revised version to be published in Phys. Rev.
Entire solutions to reaction diffusion equations
In this paper, we first use the super-sub solution method to prove the local
exponential asymptotic stability of some entire solutions to reaction diffusion
equations, including the bistable and monostable cases. In the bistable case,
we not only obtain the similar asymptotic stability result given by Yagisita in
2003, but also simplify his proof. For the monostable case, it is the first
time to discuss the local asymptotic stability of entire solutions. Next, we
will discuss the asymptotic behavior of entire solutions of bistable equations
as , since the other side was completely known. Here, our
results are obtained by use of the asymptotic stability of constant solutions
and pairs of diverging traveling front solutions of these equations, instead of
constructing the corresponding super-sub solutions as usual
A nonparametric CUSUM control chart based on the Mann-Whitney statistic
This article aims to consider a new univariate nonparametric cumulative sum
(CUSUM) control chart for small shift of location based on both change-point
model and Mann-Whitney statistic. Some comparisons on the performances of the
proposed chart with other charts as well as the properties of the test
statistic are presented. Simulations indicate that the proposed chart is
sensitive in detection of the small mean shifts of the process by a high
intensive accumulation of sample information when the underlying variable is
completely distribution-free.Comment: 13 pages, 2 tabl
Entire Solutions for the Classical Competitive Lotka-Volterra System with Diffusion in the Weak Competition Case
In this paper we are concerned with the entire solutions for the classical
competitive Lotka-Volterra system with diffusion in the weak competition. For
this purpose we firstly analyze the asymptotic behavior of traveling front
solutions for this system connecting the origin and the positive equilibrium.
Then, by using two different ways to construct pairs of coupled super-sub
solutions of this system, we obtain two different kinds of entire solutions.
The construction of the first kind of entire solutions is based on these
fronts, and their reflects as well as the solutions of the system without
diffusion. One component of the solution starts from 0 at ,
and as goes to , the two component of the entire solution will
eventually stay in a conformed region. Another kind of entire solutions is
related to some traveling front solutions of scalar equation
Topological dynamics of Zadeh's extension on the space of upper semi-continuous fuzzy sets
In this paper, some characterizations about transitivity, mildly mixing
property, -transitivity, equicontinuity, uniform rigidity and
proximality of Zadeh's extensions restricted on some invariant closed subsets
of the space of all upper semi-continuous fuzzy sets with the level-wise metric
are obtained. In particular, it is proved that a dynamical system is weakly
mixing (resp., mildly mixing, weakly mixing and -transitive,
equicontinuous, uniformly rigid) if and only if the Zadeh's extension is
transitive (resp., mildly mixing, -transitive, equicontinuous,
uniformly rigid)
Uncertainty Quantification and Composition Optimization for Alloy Additive Manufacturing Through a CALPHAD-based ICME Framework
During powder production, the pre-alloyed powder composition often deviates
from the target composition leading to undesirable properties of additive
manufacturing (AM) components. Therefore, we developed a method to perform
high-throughput calculation and uncertainty quantification by using a
CALPHAD-based ICME framework (CALPHAD: calculations of phase diagrams, ICME:
integrated computational materials engineering) to optimize the composition,
and took the high-strength low-alloy steel (HSLA) as a case study. We analyzed
the process-structure-property relationships for 450,000 compositions around
the nominal composition of HSLA-115. Properties that are critical for the
performance, such as yield strength, impact transition temperature, and
weldability, were evaluated to optimize the composition. With the same
uncertainty as the initial composition, an optimized average composition has
been determined, which increased the probability of achieving successful AM
builds by 44.7%. The present strategy is general and can be applied to other
alloy composition optimization to expand the choices of alloy for additive
manufacturing. Such a method also calls for high-quality CALPHAD databases and
predictive ICME models.Comment: 37 pages, 10 figure, 11 table
Anonymous Auction Protocol Based on Time-Released Encryption atop Consortium Blockchain
The Ethereum blockchain as a decentralized platform is so successful that
many applications deployed on it. However, for the inherent transparency
properties and the lack of privacy, deploying a financial application on top of
it is always a challenge. In this paper, we tackle this challenge and propose
an anonymous sealed-bid auction protocol based on time-released encryption atop
Consortium Blockchain. We adopt a strict digital certificate-based identity
mechanism of the consortium blockchain to permit legitimate participants, and
utilize the blind signature based on elliptic curve technology to allowing
anonymous participation. Moreover, a timed release public key encryption
algorithm is adopted to encrypt bids and prevent auctioneer from colluding with
bidders. This is completely different from the method (zero-knowledge proof)
used in other papers to prevent collusion between auctioneer and bidder. We
provide a specific analysis of our protocol, which shows that our protocol
meets anonymity and applicability.Comment: 15 pages, 3 figures, 1 table.Journal pape
Anharmonicity-Induced Criticality of Collective Excitation in a Trapped Bose-Einstein Condensate
We investigate the low energy excitations of a dilute atomic Bose gas
confined in a anharmonic trap interacting with repulsive forces. The dispersion
law of both surface and compression modes are derived and analyzed for large
numbers of atoms in the trap, which show two branches of excitation and appear
a two critical value. For a upper limit, BEC can be unstable with respect to
some specific collective excitation, while for the lower limit, the frequency
of collective excitation under anharmonic influence can be effectively lower
than that without anharmonicity. Our work reveals the key role played by the
anharmonicity and interatomic forces which introduce a rich structure in the
dynamic behavior of these new many-body systems.Comment: 19 page
Next-to-Leading-Order study on the associate production of at the LHC
The associate production at the LHC is studied completely at
next-to-leading-order (NLO) within the framework of nonrelativistic QCD. By
using three sets of color-octet long-distance matrix elements (LDMEs) obtained
in previous prompt studies, we find that only one of them can result
in a positive transverse momentum () distribution of production
rate at large region. Based on reasonable consideration to cut down
background, our estimation is measurable upto GeV with present data
sample collected at TeV LHC. All the color-octet LDMEs in
production could be fixed sensitively by including this proposed measurement
and our calculation, and then confident conclusion on polarization
puzzle could be achieved.Comment: 5 pages, 2 figure
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