نتایج جستجو برای: expectation value

تعداد نتایج: 767918  

2010
Micha-Klaus Müller Stefan Luding Thorsten Pöschel

In dense, static, polydisperse granular media under isotropic pressure, the probability density and the correlations of particle-wall contact forces are studied. Furthermore, the probability density functions of the populations of pressures measured with different sized circular pressure cells is examined. The questions answered are: (i) What is the number of contacts that has to be considered ...

2013
J. Binney B. Burnett G. Kordopatis P. J. McMillan S. Sharma T. Zwitter O. Bienaymé J. Bland-Hawthorn M. Steinmetz G. Gilmore M. E. K. Williams J. Navarro E. K. Grebel A. Helmi Q. Parker W. A. Reid G. Seabroke F. Watson R. F. G. Wyse

Probability density functions (pdfs) are determined from new stellar parameters for the distance moduli of stars for which the RAdial Velocity Experiment (RAVE) has obtained spectra with S/N ≥ 10. Single-Gaussian fits to the pdf in distance modulus suffice for roughly half the stars, with most of the other half having satisfactory two-Gaussian representations. As expected, early-type stars rare...

2013
Qingbin Meng Zhendong Li Menghai Wang Xin Zhang

In this paper we consider the optimal control problem for a insurance company. Our objective is to maximize the expectation of discounted dividends and its terminal value which represents the company liquidation value upon the time of bankruptcy. The surplus of the insurance company is governed by the Brownian motion with a constant drift and a diffusion term. The company can manage its risk ex...

1999
Marc Sher

In multiple-universe models, the constants of nature may have different values in different universes. Agrawal, Barr, Donoghue and Seckel have pointed out that the Higgs mass parameter, as the only dimensionful parameter of the standard model, is of particular interest. By considering a range of values of this parameter, they showed that the Higgs vacuum expectation value must have a magnitude ...

2003
David Seery Bruce A. Bassett

We investigate the constraints on quintessence arising from both renormalisable and non-renormalisable couplings where the 5d Planck mass is around the TeV scale. The quintessence field vacuum expectation value is typically of order the 4d Planck mass, while non-renormalisable operators are expected to be suppressed by the 5d Planck mass. Non-renormalisable operators are therefore important in ...

1997
Greg W. Anderson Sean M. Carroll

We propose a simple model in which the cosmological dark matter consists of particles whose mass increases with the scale factor of the universe. The particle mass is generated by the expectation value of a scalar field which does not have a stable vacuum state, but which is effectively stabilized by the rest energy of the ambient particles. As the universe expands, the density of particles dec...

2000
Lowell S. Brown

We have reexamined the electromagnetic corrections to the weak interaction rates for the transformation of neutrons to protons, and protons to neutrons, in the early universe, before freeze-out. We derive compact expressions for these rates in terms of thermal expectation values of products of fields, and we give explicit constructions of the terms to order e2. We disagree in several respects w...

2012
Emiliano Lorini

Some years ago (in 2003) I wrote my first paper in collaboration with Cristiano Castelfranchi who at that time was the supervisor of my Master project in Cognitive Science. The work was aimed at providing a logical formalization of the notion of expectation and of expectation-based emotions such as hope, fear, disappointment and relief. In this paper I will revisit and extend the analysis we di...

1998
Chun Liu

A supersymmetric model which naturally accommodates MeV tau neutrino within the framework of gauge mediated supersymmetry breaking is described. The lepton number violation is originally introduced in the messenger sector of the theory. A large slepton-Higgs mixing mass and a small lepton-higgsino mixing mass are generated at one-loop. Scalar tau neutrino has non-vanishing vacuum expectation va...

2003
PAUL LANGACKER Gino Segrè

There has recently been reported evidence for a possible time variation of the fine structure constant on cosmological time scales . Such variations are not surprising in any theoretical framework for the unification of basic forces involving extra dimensions or in which dimensionless couplings are related to the expectation values of scalar fields. However, the variation of α is likely to be c...

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