{"title":"Simulating nonlinear neutrino flavor evolution","authors":"H. Duan, G. Fuller, J. Carlson","doi":"10.1088/1749-4699/1/1/015007","DOIUrl":"https://doi.org/10.1088/1749-4699/1/1/015007","url":null,"abstract":"We discuss a new kind of astrophysical transport problem: the coherent evolution of neutrino flavor in core collapse supernovae. Solution of this problem requires a numerical approach which can simulate accurately the quantum mechanical coupling of intersecting neutrino trajectories and the associated nonlinearity which characterizes neutrino flavor conversion. We describe here the two codes developed to attack this problem. We also describe the surprising phenomena revealed by these numerical calculations. Chief among these is that the nonlinearities in the problem can engineer neutrino flavor transformation which is dramatically different to that in standard Mikheyev–Smirnov–Wolfenstein treatments. This happens even though the neutrino mass-squared differences are measured to be small, and even when neutrino self-coupling is sub-dominant. Our numerical work has revealed potential signatures which, if detected in the neutrino burst from a Galactic core collapse event, could reveal heretofore unmeasurable properties of the neutrinos, such as the mass hierarchy and vacuum mixing angle θ13.","PeriodicalId":89345,"journal":{"name":"Computational science & discovery","volume":"1 1","pages":"015007-015007"},"PeriodicalIF":0.0,"publicationDate":"2008-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1749-4699/1/1/015007","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60596242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Heitmann, Z. Lukic, P. Fasel, S. Habib, Michael S. Warren, M. White, J. Ahrens, L. Ankeny, R. Armstrong, Brian, O’Shea, P. Ricker, V. Springel, Joachim, Stadel
{"title":"The cosmic code comparison project","authors":"K. Heitmann, Z. Lukic, P. Fasel, S. Habib, Michael S. Warren, M. White, J. Ahrens, L. Ankeny, R. Armstrong, Brian, O’Shea, P. Ricker, V. Springel, Joachim, Stadel","doi":"10.1088/1749-4699/1/1/015003","DOIUrl":"https://doi.org/10.1088/1749-4699/1/1/015003","url":null,"abstract":"Current and upcoming cosmological observations allow us to probe structures on smaller and smaller scales, entering highly nonlinear regimes. In order to obtain theoretical predictions in these regimes, large cosmological simulations have to be carried out. The promised high accuracy from observations makes the simulation task very demanding: the simulations have to be at least as accurate as the observations. This requirement can only be fulfilled by carrying out an extensive code verification program. The first step of such a program is the comparison of different cosmology codes including gravitational interactions only. In this paper, we extend a recently carried out code comparison project to include five more simulation codes. We restrict our analysis to a small cosmological volume which allows us to investigate properties of halos. For the matter power spectrum and the mass function, the previous results hold, with the codes agreeing at the 10% level over wide dynamic ranges. We extend our analysis to the comparison of halo profiles and investigate the halo count as a function of local density. We introduce and discuss ParaView as a flexible analysis tool for cosmological simulations, the use of which immensely simplifies the code comparison task.","PeriodicalId":89345,"journal":{"name":"Computational science & discovery","volume":"1 1","pages":"015003"},"PeriodicalIF":0.0,"publicationDate":"2007-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1749-4699/1/1/015003","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60596601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Chiarappa, Karl Jansen, K. Nagai, M. Papinutto, L. Scorzato, A. Shindler, C. Urbach, U. Wenger, I. Wetzorke
{"title":"Iterative methods for overlap and twisted mass fermions","authors":"T. Chiarappa, Karl Jansen, K. Nagai, M. Papinutto, L. Scorzato, A. Shindler, C. Urbach, U. Wenger, I. Wetzorke","doi":"10.1088/1749-4699/1/1/015001","DOIUrl":"https://doi.org/10.1088/1749-4699/1/1/015001","url":null,"abstract":"We present a comparison of a number of iterative solvers of linear systems of equations for obtaining the fermion propagator in lattice quantum chromodynamics (QCD). In particular, we consider chirally invariant overlap and chirally improved Wilson (maximally) twisted mass (TM) fermions. The comparison of both formulations of lattice QCD is performed at four fixed values of the pion mass between 230 and 720 MeV. For overlap fermions we address adaptive precision and low-mode preconditioning while for TM fermions we discuss even/odd preconditioning. Taking the best available algorithms in each case we find that calculations with the overlap operator are by a factor of 30–120 more expensive than with the TM operator.","PeriodicalId":89345,"journal":{"name":"Computational science & discovery","volume":"1 1","pages":"015001"},"PeriodicalIF":0.0,"publicationDate":"2006-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1088/1749-4699/1/1/015001","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60596479","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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