In this paper we investigate the effects of the large extra dimensions on the two processes e＋ e-→＋ H^0 Z^0 Z^0 and e^＋e^-→ H^0H^0 Z^0 at linear colliders in both unpolarized and polarized collision modes. We fin...In this paper we investigate the effects of the large extra dimensions on the two processes e＋ e-→＋ H^0 Z^0 Z^0 and e^＋e^-→ H^0H^0 Z^0 at linear colliders in both unpolarized and polarized collision modes. We find that the virtual Kaluza-Klein graviton exchange can significantly enhance the cross section from their standard model expectations for these two processes. The results show that the LED effect on the process e＋ e-→＋ H^0 Z^0 Z^0 allows the observation limits on the effective scale Ms to be probed up to 9. 75 TeV and 10.1 TeV in the unpolarized and ＋-（λe＋ =1/2, λe-= -1/2） polarized beam collision modes （with Pe＋ = 0.6, Pe-=0.8）, respectively. For the process e＋ e-→＋ H^0 H^0 Z^0, these limits on Ms can be probed up to 6.06 TeV and 6.38 TeV in the unpolarized and polarized collision modes separately. We find that the λe＋ = 1/2, λe-= -1/2 polarization collision mode in both processe＋ e-→＋ H^0 Z^0 Z^0 and e＋ e-→＋ H^0 H^0 Z^0 may provide a possibility to improve the sensitivity in probing the LED effects.展开更多
Recently, a new noncommutative geometry inspired solution of the coupled Einstein Maxwell field equations including black holes in 4-dimension is found. In this paper, we generalize some aspects of this model to the R...Recently, a new noncommutative geometry inspired solution of the coupled Einstein Maxwell field equations including black holes in 4-dimension is found. In this paper, we generalize some aspects of this model to the Reissner Nordstrom （RN） like geometries with large extra dimensions. We discuss Hawking radiation process based on noncommutative inspired solutions. In this framework, existence of black hole remnant and possibility of its detection in LHC are investigated.展开更多
New unification theories predict large extra dimensions （LEDs）. If that is the case, gravity would be stronger at short ranges than what Newtonian gravity predicts. LEDs could also have effects at atomic level. In t...New unification theories predict large extra dimensions （LEDs）. If that is the case, gravity would be stronger at short ranges than what Newtonian gravity predicts. LEDs could also have effects at atomic level. In this paper we propose a new method to constrain the size of ‘gravity-only’ LEDs by analysing how these LEDs modify the energy of the atomic transitions 1s-2s and 2s-2p （Lamb shift）, in the particular case of the hydrogen and muonium atoms. We estimate these effects by using Bethe＇s non-relativistic treatment of Lamb shift. In the particular case of three LEDs, which may be a candidate to explain the interaction mechanism of dark matter particles, we have found that current knowledge in atomic spectroscopy could constrain their sizes to less than 10 μm. Although our contributions do not reach the sensitivity given by SN1987a, they are still slightly better than recent constraints given by Inverse Square Law tests of the Eoet-Wash group at Washington University, which gave R3 〈 36.6 μm.展开更多
We study fermionic zero modes in the self-dual vortex background on an extra two-dimensional Riemann surface in （5＋1） dimensions. Using the generalized Abelian-Higgs model, we obtain the inner topological structure...We study fermionic zero modes in the self-dual vortex background on an extra two-dimensional Riemann surface in （5＋1） dimensions. Using the generalized Abelian-Higgs model, we obtain the inner topological structure of the self-dual vortex and establish the exact self-duality equation with topological term. Then we analyze the Dirac operator on an extra torus and the effective Lagrangian of four-dimensional fermions with the self-dual vortex background. Solving the Dirac equation, the fermionic zero modes on a torus with the self-dual vortex background in two simple cases are obtained.展开更多
This paper aims to develop a new robust U-type test for high dimensional regression coefficients using the estimated U-statistic of order two and refitted cross-validation error variance estimation. It is proved that ...This paper aims to develop a new robust U-type test for high dimensional regression coefficients using the estimated U-statistic of order two and refitted cross-validation error variance estimation. It is proved that the limiting null distribution of the proposed new test is normal under two kinds of ordinary models.We further study the local power of the proposed test and compare with other competitive tests for high dimensional data. The idea of refitted cross-validation approach is utilized to reduce the bias of sample variance in the estimation of the test statistic. Our theoretical results indicate that the proposed test can have even more substantial power gain than the test by Zhong and Chen(2011) when testing a hypothesis with outlying observations and heavy tailed distributions. We assess the finite-sample performance of the proposed test by examining its size and power via Monte Carlo studies. We also illustrate the application of the proposed test by an empirical analysis of a real data example.展开更多
In the factor analysis model with large cross-section and time-series dimensions,we pro- pose a new method to estimate the number of factors.Specially if the idiosyncratic terms satisfy a linear time series model,the ...In the factor analysis model with large cross-section and time-series dimensions,we pro- pose a new method to estimate the number of factors.Specially if the idiosyncratic terms satisfy a linear time series model,the estimators of the parameters can be obtained in the time series model. The theoretical properties of the estimators are also explored.A simulation study and an empirical analysis are conducted.展开更多
Nonlinear dynamical stochastic models are ubiquitous in different areas.Their statistical properties are often of great interest,but are also very challenging to compute.Many excitable media models belong to such type...Nonlinear dynamical stochastic models are ubiquitous in different areas.Their statistical properties are often of great interest,but are also very challenging to compute.Many excitable media models belong to such types of complex systems with large state dimensions and the associated covariance matrices have localized structures.In this article,a mathematical framework to understand the spatial localization for a large class of stochastically coupled nonlinear systems in high dimensions is developed.Rigorous mathematical analysis shows that the local effect from the diffusion results in an exponential decay of the components in the covariance matrix as a function of the distance while the global effect due to the mean field interaction synchronizes different components and contributes to a global covariance.The analysis is based on a comparison with an appropriate linear surrogate model,of which the covariance propagation can be computed explicitly.Two important applications of these theoretical results are discussed.They are the spatial averaging strategy for efficiently sampling the covariance matrix and the localization technique in data assimilation.Test examples of a linear model and a stochastically coupled Fitz Hugh-Nagumo model for excitable media are adopted to validate the theoretical results.The latter is also used for a systematical study of the spatial averaging strategy in efficiently sampling the covariance matrix in different dynamical regimes.展开更多
基金The project supported in part by National Natural Science Foundation of China and the Special Fund of the Chinese Academy of Sciences
文摘In this paper we investigate the effects of the large extra dimensions on the two processes e＋ e-→＋ H^0 Z^0 Z^0 and e^＋e^-→ H^0H^0 Z^0 at linear colliders in both unpolarized and polarized collision modes. We find that the virtual Kaluza-Klein graviton exchange can significantly enhance the cross section from their standard model expectations for these two processes. The results show that the LED effect on the process e＋ e-→＋ H^0 Z^0 Z^0 allows the observation limits on the effective scale Ms to be probed up to 9. 75 TeV and 10.1 TeV in the unpolarized and ＋-（λe＋ =1/2, λe-= -1/2） polarized beam collision modes （with Pe＋ = 0.6, Pe-=0.8）, respectively. For the process e＋ e-→＋ H^0 H^0 Z^0, these limits on Ms can be probed up to 6.06 TeV and 6.38 TeV in the unpolarized and polarized collision modes separately. We find that the λe＋ = 1/2, λe-= -1/2 polarization collision mode in both processe＋ e-→＋ H^0 Z^0 Z^0 and e＋ e-→＋ H^0 H^0 Z^0 may provide a possibility to improve the sensitivity in probing the LED effects.
基金supported partially by Research Institute for Astronomy and Astrophysics of Maragha,Iran
文摘Recently, a new noncommutative geometry inspired solution of the coupled Einstein Maxwell field equations including black holes in 4-dimension is found. In this paper, we generalize some aspects of this model to the Reissner Nordstrom （RN） like geometries with large extra dimensions. We discuss Hawking radiation process based on noncommutative inspired solutions. In this framework, existence of black hole remnant and possibility of its detection in LHC are investigated.
基金Project supported by the National Natural Science Foundation of China (Grant No 10475114)the Foundation of Minor Planets of Purple Mountain Observatory, China
文摘New unification theories predict large extra dimensions （LEDs）. If that is the case, gravity would be stronger at short ranges than what Newtonian gravity predicts. LEDs could also have effects at atomic level. In this paper we propose a new method to constrain the size of ‘gravity-only’ LEDs by analysing how these LEDs modify the energy of the atomic transitions 1s-2s and 2s-2p （Lamb shift）, in the particular case of the hydrogen and muonium atoms. We estimate these effects by using Bethe＇s non-relativistic treatment of Lamb shift. In the particular case of three LEDs, which may be a candidate to explain the interaction mechanism of dark matter particles, we have found that current knowledge in atomic spectroscopy could constrain their sizes to less than 10 μm. Although our contributions do not reach the sensitivity given by SN1987a, they are still slightly better than recent constraints given by Inverse Square Law tests of the Eoet-Wash group at Washington University, which gave R3 〈 36.6 μm.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10275030 and 10475034 and the Fundamental Research Fund for Physics and Mathematics of Lanzhou University （No. lzu0702）
文摘We study fermionic zero modes in the self-dual vortex background on an extra two-dimensional Riemann surface in （5＋1） dimensions. Using the generalized Abelian-Higgs model, we obtain the inner topological structure of the self-dual vortex and establish the exact self-duality equation with topological term. Then we analyze the Dirac operator on an extra torus and the effective Lagrangian of four-dimensional fermions with the self-dual vortex background. Solving the Dirac equation, the fermionic zero modes on a torus with the self-dual vortex background in two simple cases are obtained.
基金supported by National Natural Science Foundation of China (Grant Nos. 11071022, 11231010 and 11471223)Beijing Center for Mathematics and Information Interdisciplinary ScienceKey Project of Beijing Municipal Educational Commission (Grant No. KZ201410028030)
文摘This paper aims to develop a new robust U-type test for high dimensional regression coefficients using the estimated U-statistic of order two and refitted cross-validation error variance estimation. It is proved that the limiting null distribution of the proposed new test is normal under two kinds of ordinary models.We further study the local power of the proposed test and compare with other competitive tests for high dimensional data. The idea of refitted cross-validation approach is utilized to reduce the bias of sample variance in the estimation of the test statistic. Our theoretical results indicate that the proposed test can have even more substantial power gain than the test by Zhong and Chen(2011) when testing a hypothesis with outlying observations and heavy tailed distributions. We assess the finite-sample performance of the proposed test by examining its size and power via Monte Carlo studies. We also illustrate the application of the proposed test by an empirical analysis of a real data example.
基金This work was partially supported by the National Natural Science Foundation of China (Grant No.10471135)
文摘In the factor analysis model with large cross-section and time-series dimensions,we pro- pose a new method to estimate the number of factors.Specially if the idiosyncratic terms satisfy a linear time series model,the estimators of the parameters can be obtained in the time series model. The theoretical properties of the estimators are also explored.A simulation study and an empirical analysis are conducted.
基金supported by the Office of Vice Chancellor for Research and Graduate Education(VCRGE)at University of Wisconsin-Madisonthe Office of Naval Research Grant ONR MURI N00014-16-1-2161+1 种基金the Center for Prototype Climate Modeling(CPCM)at New York University Abu Dhabi Research InstituteNUS Grant R-146-000-226-133
文摘Nonlinear dynamical stochastic models are ubiquitous in different areas.Their statistical properties are often of great interest,but are also very challenging to compute.Many excitable media models belong to such types of complex systems with large state dimensions and the associated covariance matrices have localized structures.In this article,a mathematical framework to understand the spatial localization for a large class of stochastically coupled nonlinear systems in high dimensions is developed.Rigorous mathematical analysis shows that the local effect from the diffusion results in an exponential decay of the components in the covariance matrix as a function of the distance while the global effect due to the mean field interaction synchronizes different components and contributes to a global covariance.The analysis is based on a comparison with an appropriate linear surrogate model,of which the covariance propagation can be computed explicitly.Two important applications of these theoretical results are discussed.They are the spatial averaging strategy for efficiently sampling the covariance matrix and the localization technique in data assimilation.Test examples of a linear model and a stochastically coupled Fitz Hugh-Nagumo model for excitable media are adopted to validate the theoretical results.The latter is also used for a systematical study of the spatial averaging strategy in efficiently sampling the covariance matrix in different dynamical regimes.
