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Search Results: 1 - 10 of 9941 matches for " Frank Gruemmer "
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Landau Migdal Theory of Interacting Fermi Systems: A Framework for Effective Theories in Nuclear Structure Physics
Frank Gruemmer,Josef Speth
Physics , 2006, DOI: 10.1088/0954-3899/32/7/R01
Abstract: We review Migdal's Theory of Finite Fermi Systems and its application to the structure of nuclei. The theory is an extension of Landau's Theory of Interacting Fermi Systems. In the first part the basic formulas are derived within the many body Green functions approach. The theory is applied to isovector electric giant resonances in medium and heavy mass nuclei. The parameterizations of the enormalized effective ph-interaction and the effective operators are discussed. It is shown that the number of free parameters are restricted due to conservation laws. We also present an extension of Migdal's theory, where the low-lying phonons are considered in a consistent manner. The extended theory is again applied to the same isovector electric giant resonances and to the analysis of $(\alpha,\alpha^\prime)$ reaction data. We point out that the extended theory is the appropriate frame for self consistent nuclear structure calculations starting from effective Lagrangians and Hamiltonians.
Complex Systems: From Nuclear Physics to Financial Markets
J. Speth,S. Drozdz,F. Gruemmer
Quantitative Finance , 2009, DOI: 10.1016/j.nuclphysa.2010.05.010
Abstract: We compare correlations and coherent structures in nuclei and financial markets. In the nuclear physics part we review giant resonances which can be interpreted as a coherent structure embedded in chaos. With similar methods we investigate the financial empirical correlation matrix of the DAX and Dow Jones. We will show, that if the time-zone delay is properly accounted for, the two distinct markets largely merge into one. This is reflected by the largest eigenvalue that develops a gap relative to the remaining, chaotic eigenvalues. By extending investigations of the specific character of financial collectivity we also discuss the criticality-analog phenomenon of the financial log-periodicity and show specific examples.
Neutron rich nuclei in density dependent relativistic Hartree-Fock theory with isovector mesons
B. Q. Chen,Z. Y. Ma,F. Gruemmer,S. Krewald
Physics , 1999, DOI: 10.1016/S0370-2693(99)00428-1
Abstract: Density dependent relativistic Hartree-Fock theory has been extended to describe properties of exotic nuclei. The effects of Fock exchange terms and of pi - and rho - meson contributions are discussed. These effects are found to be more important for neutron rich nuclei than for nuclei near the valley of stability.
Bulk properties of light deformed nuclei derived from a medium-modified meson-exchange interaction
F. Gruemmer,B. Q. Chen,Z. Y. Ma,S. Krewald
Physics , 1996, DOI: 10.1016/0370-2693(96)01126-4
Abstract: Deformed Hartree-Fock-Bogoliubov calculations for finite nuclei are carried out. As residual interaction, a Brueckner G-matrix derived from a meson-exchange potential is taken. Phenomenological medium modifications of the meson masses are introduced. The binding energies, radii, and deformation parameters of the Carbon, Oxygen, Neon, and Magnesium isotope chains are found to be in good agreement with the experimental data.
Are the contemporary financial fluctuations sooner converging to normal?
S. Drozdz,J. Kwapien,F. Gruemmer,F. Ruf,J. Speth
Physics , 2002,
Abstract: Based on the tick-by-tick price changes of the companies from the U.S. and from the German stock markets over the period 1998-99 we reanalyse several characteristics established by the Boston Group for the U.S. market in the period 1994-95, which serves to verify their space and time-translational invariance. By increasing the time scales we find a significantly more accelerated crossover from the power-law (alpha approximately 3) asymptotic behaviour of the distribution of returns towards a Gaussian, both for the U.S. as well as for the German stock markets. In the latter case the crossover is even faster. Consistently, the corresponding autocorrelation functions of returns and of the time averaged volatility also indicate a faster loss of memory with increasing time. This route towards efficiency may reflect a systematic increase of the information processing when going from past to present.
Quantifying dynamics of the financial correlations
S. Drozdz,J. Kwapien,F. Gruemmer,F. Ruf,J. Speth
Physics , 2001, DOI: 10.1016/S0378-4371(01)00289-8
Abstract: A novel application of the correlation matrix formalism to study dynamics of the financial evolution is presented. This formalism allows to quantify the memory effects as well as some potential repeatable intradaily structures in the financial time-series. The present study is based on the high-frequency Deutsche Aktienindex (DAX) data over the time-period between November 1997 and December 1999 and demonstrates a power of the method. In this way two significant new aspects of the DAX evolution are identified: (i) the memory effects turn out to be sizably shorter than what the standard autocorrelation function analysis seems to indicate and (ii) there exist short term repeatable structures in fluctuations that are governed by a distinct dynamics. The former of these results may provide an argument in favour of the market efficiency while the later one may indicate origin of the difficulty in reaching a Gaussian limit, expected from the central limit theorem, in the distribution of returns on longer time-horizons.
Dynamics of competition between collectivity and noise in the stock market
S. Drozdz,F. Gruemmer,F. Ruf,J. Speth
Physics , 1999, DOI: 10.1016/S0378-4371(00)00383-6
Abstract: Detailed study of the financial empirical correlation matrix of the 30 companies comprised by DAX within the period of the last 11 years, using the time-window of 30 trading days, is presented. This allows to clearly identify a nontrivial time-dependence of the resulting correlations. In addition, as a rule, the draw downs are always accompanied by a sizable separation of one strong collective eigenstate of the correlation matrix which, at the same time, reduces the variance of the noise states. The opposite applies to draw ups. In this case the dynamics spreads more uniformly over the eigenstates which results in an increase of the total information entropy.
Prediction oriented variant of financial log-periodicity and speculating about the stock market development until 2010
S. Drozdz,F. Gruemmer,F. Ruf,J. Speth
Physics , 2005,
Abstract: A phenomenon of the financial log-periodicity is discussed and the characteristics that amplify its predictive potential are elaborated. The principal one is self-similarity that obeys across all the time scales. Furthermore the same preferred scaling factor appears to provide the most consistent description of the market dynamics on all these scales both in the bull as well as in the bear market phases and is common to all the major markets. These ingredients set very desirable and useful constraints for understanding the past market behavior as well as in designing forecasting scenarios. One novel speculative example of a more detailed S$&$P500 development until 2010 is presented.
Decomposing the stock market intraday dynamics
J. Kwapien,S. Drozdz,F. Gruemmer,F. Ruf,J. Speth
Quantitative Finance , 2001, DOI: 10.1016/S0378-4371(02)00613-1
Abstract: The correlation matrix formalism is used to study temporal aspects of the stock market evolution. This formalism allows to decompose the financial dynamics into noise as well as into some coherent repeatable intraday structures. The present study is based on the high-frequency Deutsche Aktienindex (DAX) data over the time period between November 1997 and September 1999, and makes use of both, the corresponding returns as well as volatility variations. One principal conclusion is that a bulk of the stock market dynamics is governed by the uncorrelated noise-like processes. There exists however a small number of components of coherent short term repeatable structures in fluctuations that may generate some memory effects seen in the standard autocorrelation function analysis. Laws that govern fluctuations associated with those various components are different, which indicates an extremely complex character of the financial fluctuations.
Towards identifying the world stock market cross-correlations: DAX versus Dow Jones
S. Drozdz,F. Gruemmer,F. Ruf,J. Speth
Quantitative Finance , 2000, DOI: 10.1016/S0378-4371(01)00119-4
Abstract: Effects connected with the world globalization affect also the financial markets. On a way towards quantifying the related characteristics we study the financial empirical correlation matrix of the 60 companies which both the Deutsche Aktienindex (DAX) and the Dow Jones (DJ) industrial average comprised during the years 1990-1999. The time-dependence of the underlying cross-correlations is monitored using a time window of 60 trading days. Our study shows that if the time-zone delays are properly accounted for the two distant markets largely merge into one. This effect is particularly visible during the last few years. It is however the Dow Jones which dictates the trend.
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