KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.
A new type of superstring theory is constructed as a chiral combination of the closed D = 26 bosonic and D = 10 fermionic strings. The theory is supersymmetric, Lorentz invariant, and free of tachyons. Consistency requires the gauge group to be Spin(32)/Z 2 or £ 8 x E%.PACS numbers: ll.30. Pb, 11.30.Ly, 12.10.En Recent interest in superstring unified field theories has been sparked by the discovery of Green and Schwarz 1 that nonorientable (type I) open and closed superstrings 2 with iV= 1 supersymmetry are finite and free of anomalies if the gauge group is SO(32). Previously the only consistent, anomaly-free 3 superstring theory was that of orientable (type II) N = 2 supersymmetric closed strings. The new theory has the advantage of already containing a large (and unique) gauge group. It is much easier to contemplate this theory producing the low-energy gauge group, as well as families of chiral massless fermions, upon compactification of the original ten dimensions. Witten has discussed some of the phenomenology of this theory and has shown that it is easy to imagine compactifications that yield an SU(5) theory with any number of standard fermionic generations. 4 The anomaly cancellation mechanism of Green and Schwarz is based on group theoretical properties of SO(32) which are shared by only one other semisimple Lie group, namely E%x E s . Such a group, however, cannot appear in the standard form of open-string theory, in which gauge groups are introduced by attaching quantum numbers to the ends of the string and Chan-Paton factors 5 to the scattering amplitudes. This procedure yields only the gauge groups SO(A0 and Sp(2A0. 6 The correspondence between the lowenergy limit of existing supersymmetric string theories with anomaly-free, Z) = 10, supergravity field theories suggests the existence of a new kind of string theory whose low-energy limit would have an E s x E% gauge group. Eschewing the Chan-Paton route to gauge groups for open strings, one might try to obtain fgXfg by compactifying a higher-dimensional closedstring theory. An important clue to how such a theory might arise is provided by the work of Frenkel and Kac. 7 J In this Letter we shall outline the construction of a new kind of closed-string theory, whose low-energy limit is Z> = 10, N=l supergravity coupled to supersymmetric Yang-Mills theory with gauge group Spin(32)/Z 2 or E s x E%. This theory is constructed as a hybrid of the Z> = 10 fermionic string and the Z> = 26 bosonic string, which preserves the appealing features of both. We show that the orientable, closed heterotic 8 string has an N = 1 supersymmetric spectrum of states of positive metric, is free of tachyons and is Lorentz invariant. The requirement that gravitational and gauge anomalies be absent necessitates the compactification of the extra sixteen bosonic coordinates of the heterotic string on a maximal torus of determined radius, in a way that produces gauge groups Spin(32)/Z 2 or E s xE s .We further argue that the heterotic loop diagrams are free of all infinities-thus...
We present results of a study of neutrino oscillation based on a 766 ton/year exposure of KamLAND to reactor antineutrinos. We observe 258 nu (e) candidate events with energies above 3.4 MeV compared to 365.2+/-23.7 events expected in the absence of neutrino oscillation. Accounting for 17.8+/-7.3 expected background events, the statistical significance for reactor nu (e) disappearance is 99.998%. The observed energy spectrum disagrees with the expected spectral shape in the absence of neutrino oscillation at 99.6% significance and prefers the distortion expected from nu (e) oscillation effects. A two-neutrino oscillation analysis of the KamLAND data gives Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2). A global analysis of data from KamLAND and solar-neutrino experiments yields Deltam(2)=7.9(+0.6)(-0.5)x10(-5) eV(2) and tan((2)theta=0.40(+0.10)(-0.07), the most precise determination to date.
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