Quality evaluation of linear inequality constrained estimation by Monte Carlo sampling in parameter space

Survey Review ◽  
2020 ◽  
pp. 1-7
Author(s):  
Songlin Zhang ◽  
Jingchang Li ◽  
Kun Zhang ◽  
Jie Han
2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Pedram Tavadze ◽  
Reese Boucher ◽  
Guillermo Avendaño-Franco ◽  
Keenan X. Kocan ◽  
Sobhit Singh ◽  
...  

AbstractThe density-functional theory is widely used to predict the physical properties of materials. However, it usually fails for strongly correlated materials. A popular solution is to use the Hubbard correction to treat strongly correlated electronic states. Unfortunately, the values of the Hubbard U and J parameters are initially unknown, and they can vary from one material to another. In this semi-empirical study, we explore the U and J parameter space of a group of iron-based compounds to simultaneously improve the prediction of physical properties (volume, magnetic moment, and bandgap). We used a Bayesian calibration assisted by Markov chain Monte Carlo sampling for three different exchange-correlation functionals (LDA, PBE, and PBEsol). We found that LDA requires the largest U correction. PBE has the smallest standard deviation and its U and J parameters are the most transferable to other iron-based compounds. Lastly, PBE predicts lattice parameters reasonably well without the Hubbard correction.


2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Sourav Dey ◽  
Claudio O. Dib ◽  
Juan Carlos Helo ◽  
Minakshi Nayak ◽  
Nicolás A. Neill ◽  
...  

Abstract We consider light neutralinos of mass about 1 GeV, produced from τ lepton rare decays at Belle II, in the context of R-parity-violating (RPV) supersymmetry. With large and clean samples of τ leptons produced at the Belle II experiment, excellent sensitivity to such light neutralinos with the exotic signatures of displaced vertices is expected. We focus on two benchmark scenarios of single RPV operators, $$ {\lambda}_{311}^{\prime }{L}_3{Q}_1{\overline{D}}_1 $$ λ 311 ′ L 3 Q 1 D ¯ 1 and $$ {\lambda}_{312}^{\prime }{L}_3{Q}_1{\overline{D}}_2 $$ λ 312 ′ L 3 Q 1 D ¯ 2 , which induce both the production and decay of the lightest neutralino. For the reconstruction of a displaced vertex, we require at least two charged pions in the final states. We perform Monte-Carlo simulations for both signal and background events, and find that Belle II can explore regions in the parameter space competitive with other probes. In particular, for the $$ {\lambda}_{311}^{\prime } $$ λ 311 ′ scenario, it can put limits up to two orders of magnitude stronger than the current bounds.


2009 ◽  
Vol 5 (8) ◽  
pp. 1968-1984 ◽  
Author(s):  
Jerome Nilmeier ◽  
Matthew P. Jacobson

2004 ◽  
Vol 43 (14) ◽  
pp. 4012-4025 ◽  
Author(s):  
Wen-shiang Chen ◽  
Bhavik R. Bakshi ◽  
Prem K. Goel ◽  
Sridhar Ungarala

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