摘要:

Remarkable progress has been made over the past 30 years in understanding the flux of neutrinos coming from the sun. The so‐called “solar neutrino puzzle”, whereby the total number of electron neutrinos from the sun does not match the expected total neutrino yield can be now understood in the context of neutrino flavor transformations. The Sudbury Neutrino Observatory has contributed to understanding the solar neutrino problem by measuring both the electron and non‐electron components of the solar neutrino flux. The Sudbury Neutrino Observatory is a 1000 T D2O Cerenkov detector that is sensitive to8B neutrinos produced in the sun. By using the energy, radius, and direction with respect to the sun, the SNO experiment can separately determine the rates of the charged current, neutral current and electron scattering reactions of neutrinos on deuterium. Assuming an undistorted8B spectrum, thevecomponent of the8B solar flux is&fgr;e = 1.76−0.05+0.05(stat.)−0.09+0.09 (syst.) × 106 cm−2s−1based on events with a measured kinetic energy above 5 MeV. The non‐vecomponent is&fgr;&mgr;&tgr; = 3.41−0.45+0.45(stat.)−0.45+0.48 (syst.) × 106 cm−2s−1, 5.3&sgr; greater than zero, providing strong evidence for solarveflavor transformation. The total flux measured with the NC reaction is&fgr;NC = 5.09−0.43+0.44(stat.)−0.43+0.46 (syst.) × 106 cm−2s−1, consistent with the Standard Solar Model. A global solar neutrino analysis in terms of matter‐enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543486

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

Super‐Kamiokande’s measurements of the solar and atmospheric neutrino flux yielded first evidence for oscillation of atmosphericv&mgr;’s intov&tgr;’s and (together with data from the SNO experiment) first evidence for oscillation of solarve’s intov&mgr;’s orv&tgr;’s. Data from Super‐Kamiokande also constrained the neutrino mixing in both cases to be large. In Super‐Kamiokande, the flux and energy spectrum of the first long baseline acceleratorv&mgr;’s were measured, they favor neutrino oscillations consistent with the atmospheric neutrino analysis. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543487

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

This report gives the status of the most recent round of accelerator‐based experiments to release neutrino oscillation measurements or limits, as well as those currently planned in the near future. The report concludes with a discussion of a few of the many possible future experiments to take the next steps in this rapidly‐evolving field. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543488

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The MiniBooNE experiment has recently started a search forv&mgr;→veoscillations at Fermilab. This will provide a definitive test of the LSND results which show evidence for neutrino oscillation. The MiniBooNE neutrino source and detector are both now operational and data taking has begun. We describe the experiment, report on the status, and show the expected sensitivity to neutrino oscillations. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543489

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The NuTeV experiment has performed precision measurements of the ratio of neutral‐current to charged‐current cross‐sections in high rate, high energy neutrino and anti‐neutrino beams on a dense, primarily steel, target. The separate neutrino and anti‐neutrino beams, high statistics, and improved control of other experimental systematics, allow the determination of electroweak parameters with significantly greater precision than pastvNscattering experiments. Our null hypothesis test of the standard model prediction measuressin2 &thgr;W(on‐shell) = 0.2277 ± 0.0013(stat) ± 0.0009(syst), a value which is 3.0&sgr; above the prediction. We discuss possible explanations for and implications of this discrepancy. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543490

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The theoretical interpretation of the current neutrino phenomenology is reviewed, in the context of three and four neutrino mixing. We discuss the status of atmosphericv&mgr;oscillations and the recent indications from the KEK‐to‐Kamioka (K2K) experiment. We also review the status of solarveoscillations after the Sudbury Neutrino Observatory (SNO) measurements. The three‐neutrino mixing scenario emerges as a consistent theoretical interpretation of solar, atmospheric, and reactor data. Conversely, the inclusion of LSND accelerator data in an extended four‐neutrino scenario generates a “tension” between data subsets in global fits. We also comment about the role of possible new neutrino interactions. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543491

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We present a short review of the existing evidence in favor of neutrino mass and neutrino oscillations which come from different kinds of experiments. We focus our attention in particular on solar neutrinos, presenting a review of some recent analysis of all available neutrino oscillation evidence in Solar experiments including the recentSNO CCandNCdata. We present in detail the power of the reactor experiment KamLAND for discriminating existing solutions to the SNP and giving accurate information on neutrino masses and mixing angles. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543492

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

The renormalization group equations for the general 2 × 2, complex, neutrino mass matrix are shown to have exact, analytic solutions. Simple formulas are given for the physical mixing angle, mass ratio and intrinsic CP phase. We also establish a (complex) renormalization invariant relating these parameters. For three flavors, three invariants are obtained. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543493

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

It is shown how, in a class of models, the sign of the baryon number of the universe can be related to CP violation in neutrino oscillation experiments. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543494

出版商:AIP    

年代:1903

数据来源: AIP

摘要:

We show how, with aid from aU(1) flavor symmetry, the hierarchical structure in the charged fermion sector and a democratic approach for neutrinos that yields large solar and atmospheric neutrino mixings can be simultaneously realized in the MSSM framework. InSU(5), due to the unified multiplets, we encounter difficulties. Namely, democracy for the neutrinos leads to a wrong hierarchical pattern for charged fermion masses and mixings. We discuss how this is overcome in flippedSU(5). We then proceed to an example based on 5D SUSYSU(5) GUT in which the neutrino democracy idea can be realized. A crucial role is played by bulk states, the so‐called ‘copies’, which are split by compactifying the fifth dimension on anS(1)/Z2×Z′2orbifold. © 2003 American Institute of Physics

ISSN:0094-243X    

DOI:10.1063/1.1543495

出版商:AIP    

年代:1903

数据来源: AIP