摘要:

A group theoretical generalization of the well-known Georgi–Jarlskog relations(m&mgr;/mr)=3(ms/mb)and(me/m&mgr;)=(1/3)2(md/ms)to neutrinos is found in the context ofSO(10).The new relations are(m&ngr;&mgr;/m&ngr;&tgr;)=16(mc/mt),and(m&ngr;e/m&ngr;&mgr;)=(1/16)2(mu/mc),which are consistent with present neutrino data, assuming the MSW solution for solar neutrinos. Inclusion of the LSND result with a constrained set of parameters is analyzed. With Abelian flavor symmetries dictating the form of the neutrino mass matrix we classify all consistent four and five parameter models that accommodate simultaneously the solar, atmospheric and LSND neutrino data. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328876

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Working in the framework of three chiral neutrinos with Majorana masses, we investigate a scenario first realized in an explicit model by Zee: that the neutrino mass matrix is strictly off-diagonal in the flavor basis, with all its diagonal entries precisely zero. This CP-conserving ansatz leads to two relations among the three mixing angles(&thgr;1,&thgr;2,&thgr;3)and two squared mass differences. We impose the constraint|m32−m22|≫|m22−m12|to conform with experiment, which requires the&thgr;ito lie nearby one of four 1-parameter domains in &thgr;-space. We exhibit the implications for solar and atmospheric neutrino oscillations in each of these cases. A unique version of the Zeeansatzsurvives confrontation with experimental data, one which necessarily involves maximal just-so vacuum oscillations of solar neutrinos. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328877

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

There are now strong hints suggesting that neutrinos do have a mass after all. If they do have a mass, it would have to be tiny. Why is it so? Is it Dirac or Majorana? Can one build a model in which a teeny, tiny Dirac neutrino mass arises in a natural way? Can one learn something else other than just neutrino masses? What are the extra phenomenological consequences of such a model? These are the questions that I will try to focus on in this talk. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328878

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

What we call the Anti-GUT model is extended a bit to include also right handed neutrinos and thus make use of the see-saw mechanism for neutrino masses. This model consists in assigning gauge quantum numbers to the known Weyl fermions and the three see-saw right handed neutrinos. Each family (generation) is given its own Standard Model gauge fields and a gauged field coupled to theB−Lquantum number for that family alone. Further we assign a rather limited number of Higgs fields, so as to break these gauge groups down to the Standard Model gauge group and to fit w.r.t. order of magnitude the spectra and mixing angles of the quarks and leptons. We find a rather good fit, which for neutrino oscillations favor the small mixing angle MSW solution, although the mixing angle predicted is closest to the upper side of the uncertainty range for the measured solar neutrino mixing angle. An idea to make a “finetuning”-principle to “explain” the large ratios found empirically in physics such as “why is the weak scale low compared to the Planck scale?” is proposed (solving a hierarchy problem related problem). Some speculative further extension is supposed to “explain” that we have three families. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328879

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

After a short historical review, the present experimental situation is reviewed and several theoretical schemes are discussed, including a general description of Kaluza-Klein sterile neutrino towers. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328880

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The LSND experiment at Los Alamos has conducted searches for&ngr;¯&mgr;→&ngr;¯eoscillations using&ngr;¯&mgr;from&mgr;+decay at rest and for&ngr;&mgr;→&ngr;eoscillations using&ngr;&mgr;from&pgr;+decay in flight. For the&ngr;¯&mgr;→&ngr;¯esearch, a total excess of83.3±21.2±12.0events is observed withe+energy between 20 and 60 MeV, while for the&ngr;&mgr;→&ngr;esearch, a total excess of18.1±6.6±4.0events is observed withe−energy between 60 and 200 MeV. If attributed to neutrino oscillations, the most favored allowed region from a fit to the entire data sample is a band from 0.2 to 2.0 eV2. This result implies that at least one neutrino has a mass greater than 0.4 eV/c2and that neutrinos contribute more than 1&percent; to the mass of the universe. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328881

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

There are presently three experimental indications of neutrino oscillations from solar, atmospheric, and the LSND neutrino experiments. In the near future, these indications will be checked using terrestrial neutrino beams. At Fermilab, the Minos and MiniBooNE experiments will make definitive explorations of the atmospheric and LSND results respectively. Studies of a future &ngr;-factory program using a muon storage ring show that such a facility would allow measurements of other neutrino mixing parameters, the neutrino mass hierarchy, and possibly CP violations. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328882

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

Results from the first 1117 days of Super-Kamiokande’s solar neutrino data are presented, including the absolute flux, energy spectrum, day/night and seasonal variation. The possibility of MSW and vacuum oscillations is discussed in light of these results. Results from the first 1144 days of Super-K’s atmospheric neutrino analysis are also presented, including the evidence for&ngr;&pgr;→&ngr;&tgr;oscillations, against&ngr;&mgr;→&ngr;sterileoscillations, and the current limits on proton decay. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328883

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

The Sudbury Neutrino Observatory (SNO) is a 1 kiloton heavy water, 10,000 phototube, real-time, state of the art second generation water Cerenkov detector designed primarily to study solar neutrinos. The SNO detector has been taking high quality production neutrino data for the last seven months. Water assays and many electronic and source calibration runs have been performed to study the detector cleanliness, response and systematics. It has met or exceeded all design goals and expectations. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328884

出版商:AIP    

年代:1900

数据来源: AIP

摘要:

A neutrino mass-mixing scheme which explains qualitatively all present evidence for neutrino mass (the solar and atmospheric neutrino deficits, LSND, and significant hot dark matter) also successfully avoids the “alpha effect”, allowing r-process nucleosynthesis in the neutrino-heated ejecta of supernovae. The properties of neutrinos required to ensure production of heavy nuclei provides independent evidence for (1) at least one light sterile neutrino,&ngr;s;(2) a near maximally-mixed&ngr;&mgr;−&ngr;&tgr;doublet (which also explains the atmospheric anomaly and provides hot dark matter) split from a lower mass&ngr;e−&ngr;sdoublet (needed also for the solar&ngr;edeficit); (3)&ngr;&mgr;−&ngr;emixing≳10−4;and (4) a splitting between the doublets (measured by the&ngr;&mgr;−&ngr;emass difference) ≳1 eV2, favoring the upper part of the LSND range. There is a quantitative problem with the solar observations, which do not in detail fit this or any other model. If, however, the&ngr;sis a bulk neutrino in extra dimensions the nearness in mass of the zero mode to the&ngr;eprovides vacuum oscillations, while the Kaluza-Klein states give MSW oscillations, and all the solar data can be fit. ©2000 American Institute of Physics.

ISSN:0094-243X    

DOI:10.1063/1.1328885

出版商:AIP    

年代:1900

数据来源: AIP