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Search Results: 1 - 10 of 11307 matches for " George Bathas "
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A better large $N$ expansion for chiral Yukawa models
George Bathas,Herbert Neuberger
Physics , 1992, DOI: 10.1016/0920-5632(93)90291-D
Abstract: We consider the most general renormalizable chiral Yukawa model with $SU(3)_{\rm color}$ replaced by $SU(N_c)$, $SU(2)_{\rm L}$ replaced by $SU(N_w )$ and $U(1)_{Y}$ replaced by $U(1)^{N_w -1}$ in the limit $N_c \rightarrow\infty$, $N_w \rightarrow\infty$ with the ratio $\rho=\sqrt{{N_w}\over{N_c}} \ne 0,\infty$ held fixed. Since for $N_w \ge 3$ only one renormalizable Yukawa coupling per family exists and there is no mixing between families the limit is appropriate for the description of the effects of a heavy top quark when all the other fermions are taken to be massless. The large $N=\sqrt{N_{c} N_{w}}$ expansion is expected to be no worse quantitatively in this model that in the purely scalar case and the $N=\infty$ limit is soluble even when the model is regularized non--perturbatively. A rough estimate of the triviality bound on the Yukawa coupling is equivalent to $m_t \le 1~TeV$.
Left-Right Asymmetry in $\bar{p}p \rightarrow π^- π^+$
George Bathas,W. M. Kloet
Physics , 1993, DOI: 10.1103/PhysRevC.47.2207
Abstract: Results for d$\sigma$/d$\Omega$ and $A_N$ in the reaction $\bar{p}p \rightarrow \pi^- \pi^+$ are predicted by a simple quark model. They are compared to recent experimental data from LEAR, as well as to previous predictions from nucleon-exchange models. At low energy the quark model does better than the nucleon-exchange models, but the overall comparison to experiment remains poor. In particular, the double-dip structure of the experimental $A_N$ data is only partly represented. This shortcoming of the simple quark model is traced back to a too small J=2 amplitude. This has interesting implications for the range of this specific annihilation process.
Chiral Yukawa models in the planar limit
G. Bathas,H. Neuberger
Physics , 1992, DOI: 10.1016/0370-2693(92)90906-K
Abstract: We consider the most general renormalizable chiral Yukawa model with $SU(3)_{\rm color}$ replaced by $SU(N_c)$, $SU(2)_{\rm L}$ replaced by $SU(N_w )$ and $U(1)_{Y}$ replaced by $U(1)^{N_w -1}$ in the limit $N_c \rightarrow\infty$, $N_w \rightarrow\infty$ with the ratio $\rho=\sqrt{{N_w}\over{N_c}} \ne 0,\infty$ held fixed. Since for $N_w \ge 3$ only one renormalizable Yukawa coupling per family exists and there is no mixing between families the limit is appropriate for the description of the effects of a heavy top quark when all the other fermions are taken to be massless. A rough estimate of the triviality bound on the Yukawa coupling is equivalent to $m_t \le 1~TeV$.
Generalized $^3P_0$ and $^3S_1$ Annihilation Potentials for $\bar{p}p$ Decay into Two Mesons based on a Simple Quark Model
G. Bathas,W. M. Kloet
Physics , 1993, DOI: 10.1016/0370-2693(93)90681-7
Abstract: Within the quark model a generalization is proposed of the commonly used annihilation potential to describe antiproton-proton annihilation into two mesons, the so-called $^3P_0$ and $^3S_1$ mechanisms. This generalized potential treats the two mechanisms in a more symmetric way, has additional angular dependence, and results in an expanded set of selection rules.
Two and Three-Dimensional Spin Systems with Gonihedric Action
G. K. Bathas,E. Floratos,G. K. Savvidy,K. G. Savvidy
Physics , 1995, DOI: 10.1142/S0217732395002829
Abstract: We perform numerical simulations of the two and three-dimensional spin systems with competing interaction. They describe the model of random surfaces with linear-gonihedric action.The degeneracy of the vacuum state of this spin system is equal to $~~d \cdot 2^{N}~~$ for the lattice of the size $~N^{d}~$. We observe the second order phase transition of the three-dimensional system, at temperature $\beta_{c} \simeq 0.43932$ which almost coincides with $\beta_{c}$ of the 2D Ising model. This confirms the earlier analytical result for the case when self-interaction coupling constant $k$ is equal to zero. We suggest the full set of order parameters which characterize the structure of the vacuum states and of the phase transition.
Venture Capital and Innovation in Europe  [PDF]
George Geronikolaou, George Papachristou
Modern Economy (ME) , 2012, DOI: 10.4236/me.2012.34058
Abstract: In this paper we search for evidence signifying whether VC activity is demand or supply stimulated. Namely, we examine whether innovation and entrepreneurship are fostered by Venture Capital (VC) investments or whether innovative entrepreneurship is a precondition of a VC involvement. Based on a European panel of VC investments, we test the direction of causality between VC and innovation (proxied by annual patent applications at the European Patents Office). We present evidence indicating that causality runs from patents to VC suggesting that, in Europe, innovation seems to create a demand for VC and not VC a supply of innovation. In this sense, innovative ideas seem to lack more than funds in Europe. We explain our findings on the basis of information asymmetry issues and irreversibility considerations of VC investments.
The Index of Invariant Subspaces of Bounded below Operators on Banach Spaces  [PDF]
George Chailos
Advances in Pure Mathematics (APM) , 2012, DOI: 10.4236/apm.2012.22018
Abstract: For an operator on a Banach space , let be the collection of all its invariant subspaces. We consider the index function on and we show, amongst others, that if is a bounded below operator and if , , then If in addition are index 1 invariant subspaces of , with nonzero intersection, we show that . Furthermore, using the index function, we provide an example where for some , holds .
General Markowitz Optimization Problems  [PDF]
George Stoica
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.312A281
Abstract:

We solve two Markowitz optimization problems for the one-step financial model with a finite number of assets. In our results, the classical (inefficient) constraints are replaced by coherent measures of risk that are continuous from below. The methodology of proof requires optimization techniques based on functional analysis methods. We solve explicitly both problems in the important case of Tail Value at Risk.

A Spectral Integral Equation Solution of the Gross-Pitaevskii Equation  [PDF]
George Rawitscher
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410A3009
Abstract:

The Gross-Pitaevskii equation (GPE), that describes the wave function of a number of coherent Bose particles contained in a trap, contains the cube of the normalized wave function, times a factor proportional to the number of coherent atoms. The square of the wave function, times the above mentioned factor, is defined as the Hartree potential. A method implemented here for the numerical solution of the GPE consists in obtaining the Hartree potential iteratively, starting with the Thomas Fermi approximation to this potential. The energy eigenvalues and the corresponding wave functions for each successive potential are obtained by a spectral method described previously. After approximately 35 iterations a stability of eight significant figures for the energy eigenvalues is obtained. This method has the advantage of being physically intuitive, and could be extended to the calculation of a shell-model potential in nuclear physics, once the Pauli exclusion principle is allowed for.

Rethinking the Formal Methodology (II): Cognitive Content of Relativity (On the Centenary of General Relativity)  [PDF]
George Kirakosyan
International Journal of Astronomy and Astrophysics (IJAA) , 2016, DOI: 10.4236/ijaa.2016.61004
Abstract: An attempt to epistemological completion of formal-math theories of relativity is presented. Causal interpretations of SR and GR are suggested. The problem to physical gist of gravity is explained as a contradiction of cognition vs. intuition. Gravity phenomena are represented as unexplored peculiarity of basic particles. The gravity constant is deduced from the known parameters of the electron.
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