A Power Law Model for Time Dependent Behavior of Soils

The research focuses on a difference between Federal Highway Administration (FHWA) guidelines and Texas Department of Transportation (TxDOT) design practices for soil nail walls in high plasticity (i.e., plasticity index (PI) ≥ 15) clays. It will be going to validate TxDOT’s design approach, and then extending the topic to study time dependent behavior of soils, specifically the creep failure and the prediction of long-term deformation, followed by proposing some methods to reduce deformation caused by creep in practice. A power law model is proposed to describe time dependent behavior of soils. The proposed model is fully demonstrated through enormous laboratory tests on three different soils, data from literature, four kinds of field tests and one field practice. All objectives are fulfilled in this dissertation. The outcome of this research will give a support to TxDOT’s design practice then clarify (or even remove) the creep behavior restrictions in high PI clays in later revision of GEC#7. It will also increase the understanding of time dependent behavior of soils and its application in areas and circumstances where it was previously ignored. Besides, it will be useful to researchers and engineers for being able to reasonably predict long-term deformation in practice with the power law model. It also suggests three methods to reduce creep deformation in practice

Cosmic e^\pm, \bar p, \gamma and neutrino rays in leptocentric dark matter models

Dark matter annihilation is one of the leading explanations for the recently observed $e^\pm$ excesses in cosmic rays by PAMELA, ATIC, FERMI-LAT and HESS. Any dark matter annihilation model proposed to explain these data must also explain the fact that PAMELA data show excesses only in $e^\pm$ spectrum but not in anti-proton. It is interesting to ask whether the annihilation mode into anti-proton is completely disallowed or only suppressed at low energies. Most models proposed have negligible anti-protons in all energy ranges. We show that the leptocentric $U(1)_{B-3L_i}$ dark matter model can explain the $e^\pm$ excesses with suppressed anti-proton mode at low energies, but at higher energies there are sizable anti-proton excesses. Near future data from PAMELA and AMS can provide crucial test for this type of models. Cosmic $\gamma$ ray data can further rule out some of the models. We also show that this model has interesting cosmic neutrino signatures.Comment: Latex 20 pages and five figures. References adde

Defense Expenditure and Economic Growth under External Predation

This paper develops a growth model of a country under a Hobbesian environment with international conflicts where national defense is the only way to prevent external predation. The long run growth path is determined by the equilibrium of a dynamic game with three players, the external predator, the government and the family. The equilibrium growth path has three phases, submissive equilibrium, tolerant equilibrium and full-protected equilibrium. Different defense strategies result in different growth prospects and sustainable growth will endogenously induce adjustment of defense strategies.economic growth; predate; defense expenditure

Stock market driven acquisitions versus the Q theory of takeovers – The UK evidence

Authors' draft issued as working paper dated June 2009. Final version published in Journal of Business Finance and Accounting. Available online at http://onlinelibrary.wiley.com/Using a sample of UK mergers and acquisitions from 1985-2004, we show that equity over-valuation appears to play an important role in the determination of financing method. Our results are broadly consistent with those theories based upon market over-valuation driving mergers and their financing, rather than a Q-theory explanation. In some contrast to the US results of Dong et al. (2006) we find that proxies for over-valuation appear to be the more persuasive explanation for acquisition financing behaviour in the UK. Given the evidence in favour of valuation effects, we argue that a treatment effects model is necessary in investigating the long-run performance of acquirers. Taken together with results from a univariate analysis, such a model reveals some modest support for the Shleifer and Vishny (2003) hypothesis

The ρ\rho-meson longitudinal leading-twist distribution amplitude

In the present paper, we suggest a convenient model for the vector $\rho$-meson longitudinal leading-twist distribution amplitude $\phi_{2;\rho}^\|$, whose distribution is controlled by a single parameter $B^\|_{2;\rho}$. By choosing proper chiral current in the correlator, we obtain new light-cone sum rules (LCSR) for the $B\to\rho$ TFFs $A_1$, $A_2$ and $V$, in which the $\delta^1$-order $\phi_{2;\rho}^\|$ provides dominant contributions. Then we make a detailed discussion on the $\phi_{2;\rho}^\|$ properties via those $B\to\rho$ TFFs. A proper choice of $B^\|_{2;\rho}$ can make all the TFFs agree with the lattice QCD predictions. A prediction of $|V_{\rm ub}|$ has also been presented by using the extrapolated TFFs, which indicates that a larger $B^{\|}_{2;\rho}$ leads to a larger $|V_{\rm ub}|$. To compare with the BABAR data on $|V_{\rm ub}|$, the longitudinal leading-twist DA $\phi_{2;\rho}^\|$ prefers a doubly-humped behavior.Comment: 7 pages, 3 figures. Discussions improved and references updated. To be published in Phys.Lett.

A Power Law Model for Time Dependent Behavior of Soils

The research focuses on a difference between Federal Highway Administration (FHWA) guidelines and Texas Department of Transportation (TxDOT) design practices for soil nail walls in high plasticity (i.e., plasticity index (PI) ≥ 15) clays. It will be going to validate TxDOT’s design approach, and then extending the topic to study time dependent behavior of soils, specifically the creep failure and the prediction of long-term deformation, followed by proposing some methods to reduce deformation caused by creep in practice. A power law model is proposed to describe time dependent behavior of soils. The proposed model is fully demonstrated through enormous laboratory tests on three different soils, data from literature, four kinds of field tests and one field practice. All objectives are fulfilled in this dissertation. The outcome of this research will give a support to TxDOT’s design practice then clarify (or even remove) the creep behavior restrictions in high PI clays in later revision of GEC#7. It will also increase the understanding of time dependent behavior of soils and its application in areas and circumstances where it was previously ignored. Besides, it will be useful to researchers and engineers for being able to reasonably predict long-term deformation in practice with the power law model. It also suggests three methods to reduce creep deformation in practice

Renormalization group improved pQCD prediction for Υ(1S)\Upsilon(1S) leptonic decay

The complete next-to-next-to-next-to-leading order short-distance and bound-state QCD corrections to $\Upsilon(1S)$ leptonic decay rate $\Gamma(\Upsilon(1S)\to \ell^+\ell^-)$ has been finished by Beneke {\it et al.} \cite{Beneke:2014qea}. Based on those improvements, we present a renormalization group (RG) improved pQCD prediction for $\Gamma(\Upsilon(1S)\to \ell^+\ell^-)$ by applying the principle of maximum conformality (PMC). The PMC is based on RG-invariance and is designed to solve the pQCD renormalization scheme and scale ambiguities. After applying the PMC, all known-type of $\beta$-terms at all orders, which are controlled by the RG-equation, are resummed to determine optimal renormalization scale for its strong running coupling at each order. We then achieve a more convergent pQCD series, a scheme- independent and more accurate pQCD prediction for $\Upsilon(1S)$ leptonic decay, i.e. $\Gamma_{\Upsilon(1S) \to e^+ e^-}|_{\rm PMC} = 1.270^{+0.137}_{-0.187}$ keV, where the uncertainty is the squared average of the mentioned pQCD errors. This RG-improved pQCD prediction agrees with the experimental measurement within errors.Comment: 11 pages, 4 figures. Numerical results and discussions improved, references updated, to be published in JHE

Degeneracy Relations in QCD and the Equivalence of Two Systematic All-Orders Methods for Setting the Renormalization Scale

The Principle of Maximum Conformality (PMC) eliminates QCD renormalization scale-setting uncertainties using fundamental renormalization group methods. The resulting scale-fixed pQCD predictions are independent of the choice of renormalization scheme and show rapid convergence. The coefficients of the scale-fixed couplings are identical to the corresponding conformal series with zero $\beta$-function. Two all-orders methods for systematically implementing the PMC-scale setting procedure for existing high order calculations are discussed in this article. One implementation is based on the PMC-BLM correspondence \mbox{(PMC-I)}; the other, more recent, method \mbox{(PMC-II)} uses the ${\cal R}_\delta$-scheme, a systematic generalization of the minimal subtraction renormalization scheme. Both approaches satisfy all of the principles of the renormalization group and lead to scale-fixed and scheme-independent predictions at each finite order. In this work, we show that PMC-I and PMC-II scale-setting methods are in practice equivalent to each other. We illustrate this equivalence for the four-loop calculations of the annihilation ratio $R_{e^+ e^-}$ and the Higgs partial width $\Gamma(H\to b\bar{b})$. Both methods lead to the same resummed (`conformal') series up to all orders. The small scale differences between the two approaches are reduced as additional renormalization group $\{\beta_i\}$-terms in the pQCD expansion are taken into account. We also show that {\it special degeneracy relations}, which underly the equivalence of the two PMC approaches and the resulting conformal features of the pQCD series, are in fact general properties of non-Abelian gauge theory.Comment: 7 pages, 1 figur