Tests on B−L symmetry breaking models are important probes to search for new physics. One proposed model with Δ(B−L)=2 involves the oscillations of a neutron to an antineutron. In this paper, a new ...limit on this process is derived for the data acquired from all three operational phases of the Sudbury Neutrino Observatory experiment. The search concentrated on oscillations occurring within the deuteron, and 23 events were observed against a background expectation of 30.5 events. These translated to a lower limit on the nuclear lifetime of 1.48×1031 yr at 90% C.L. when no restriction was placed on the signal likelihood space (unbounded). Alternatively, a lower limit on the nuclear lifetime was found to be 1.18×1031 yr at 90% C.L. when the signal was forced into a positive likelihood space (bounded). Values for the free oscillation time derived from various models are also provided in this article. This is the first search for neutron-antineutron oscillation with the deuteron as a target.
Since its experimental discovery, many phenomenological theories successfully reproduced the rapid rise of the Hall number nH, going from p at low doping to 1+p at the critical doping p* of the ...pseudogap in superconducting cuprates. Further comparison with experiments is now needed in order to narrow down candidates. In this paper, we consider three previously successful phenomenological theories in a unified formalism-an antiferromagnetic mean field (AF), a spiral incommensurate antiferromagnetic mean field (sAF), and the Yang-Rice-Zhang (YRZ) theory. We find a rapid rise in the specific heat and a rapid drop in the Seebeck coefficient for increasing doping across the transition in each of those models. The predicted rises and drops are locked, not to p*, but to the doping where antinodal electron pockets, characteristic of each model, appear at the Fermi surface shortly before p*. While such electron pockets are still to be found in experiments, we discuss how they could provide distinctive signatures for each model. We also show that the range of doping where those electron pockets would be found is strongly affected by the position of the van Hove singularity.
The Sudbury Neutrino Observatory (SNO) used an array of 3He proportional counters to measure the rate of neutral-current interactions in heavy water and precisely determined the total active (nu_x) ...8B solar neutrino flux. This technique is independent of previous methods employed by SNO. The total flux is found to be 5.54_-0.31;+0.33(stat)-0.34+0.36(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of solar and reactor neutrino results yields Deltam2=7.59_-0.21;+0.19x10(-5) eV2 and theta=34.4_-1.2;+1.3 degrees. The uncertainty on the mixing angle has been reduced from SNO's previous results.
Superfluid stiffness ρs is a defining characteristic of the superconducting state, allowing phase coherence and supercurrent. It is accessible experimentally through the penetration depth. ...Coexistence of d-wave superconductivity with other phases in underdoped cuprates, such as antiferromagnetism or charge-density waves, may drastically alter ρs. To shed light on this physics, the zero-temperature value of ρs=ρzz along the c axis was computed for different values of Hubbard interaction U and different sets of tight-binding parameters describing the high-temperature superconductors YBCO and NCCO. We used cellular dynamical mean-field theory for the one-band Hubbard model with exact diagonalization as impurity solver and state-of-the-art bath parametrization. We conclude that Mott physics plays a dominant role in determining the superfluid stiffness on the hole-doped side of the phase diagram. On the electron-doped side, antiferromagnetism wins over superconductivity near half-filling. But, upon approaching optimal electron-doping, homogeneous coexistence between superconductivity and antiferromagnetism causes the superfluid stiffness to drop sharply. Hence, on the electron-doped side, it is competition between antiferromagnetism and d-wave superconductivity that plays a dominant role in determining the value of ρzz near half-filling. At large overdoping, ρzz behaves in a more BCS-type manner in both the electron- and hole-doped cases. We comment on some qualitative implications of these results for the superconducting transition temperature.
The presence of incommensurate spiral spin-density waves (SDW) has been proposed to explain the p (hole doping) to 1+p jump measured in the Hall number nH at a doping p*. Here we explore ...incommensurate collinear SDW as another possible explanation of this phenomenon, distinct from the incommensurate spiral SDW proposal. We examine the effect of different SDW strengths and wave vectors, and we find that the nH∼p behavior is hardly reproduced at low doping. Furthermore, the calculated nH and Fermi surfaces give characteristic features that should be observed; thus, the lack of these features in experiment suggests that the incommensurate collinear SDW is unlikely to be a good candidate to explain the nH∼p observed in the pseudogap regime.
The Sudbury Neutrino Observatory (SNO) has confirmed the standard solar model and neutrino oscillations through the observation of neutrinos from the solar core. In this paper we present a search for ...neutrinos associated with sources other than the solar core, such as gamma-ray bursts and solar flares. We present a new method for looking for temporal coincidences between neutrino events and astrophysical bursts of widely varying intensity. No correlations were found between neutrinos detected in SNO and such astrophysical sources.
A search has been made for neutrinos from the hep reaction in the Sun and from the diffuse supernova neutrino background (DSNB) using data collected during the first operational phase of the Sudbury ...Neutrino Observatory, with an exposure of 0.65 ktons yr. For the hep neutrino search, two events are observed in the effective electron energy range of 14.3 MeV < T sub(eff) < 20 MeV, where 3.1 background events are expected. After accounting for neutrino oscillations, an upper limit of 2.3 x 10 super(4) cm super(-2) s super(-1) at the 90% confidence level is inferred on the integral total flux of hep neutrinos. For DSNB neutrinos, no events are observed in the effective electron energy range of 21 MeV < T sub(eff) < 35 MeV, and, consequently, an upper limit on the u sub(e) component of the DSNB flux in the neutrino energy range of 22.9 MeV < E sub(u)< 36.9 MeV of 70 cm super(-2) s super(-1) is inferred at the 90% confidence level. This is an improvement by a factor of 6.5 on the previous best upper limit on the hep neutrino flux and by 2 orders of magnitude on the previous upper limit on the u sub(e) component of the DSNB flux.
Results are reported from a joint analysis of Phase I and Phase II data from the Sudbury Neutrino Observatory. The effective electron kinetic energy threshold used is T{sub eff}=3.5 MeV, the lowest ...analysis threshold yet achieved with water Cherenkov detector data. In units of 10{sup 6} cm{sup -2} s{sup -1}, the total flux of active-flavor neutrinos from {sup 8}B decay in the Sun measured using the neutral current (NC) reaction of neutrinos on deuterons, with no constraint on the {sup 8}B neutrino energy spectrum, is found to be PHI{sub NC}=5.140{sub -0.158}{sup +0.160}(stat){sub -0.117}{sup +0.132}(syst). These uncertainties are more than a factor of 2 smaller than previously published results. Also presented are the spectra of recoil electrons from the charged current reaction of neutrinos on deuterons and the elastic scattering of electrons. A fit to the Sudbury Neutrino Observatory data in which the free parameters directly describe the total {sup 8}B neutrino flux and the energy-dependent nu{sub e} survival probability provides a measure of the total {sup 8}B neutrino flux PHI{sub {sup 8}{sub B}}=5.046{sub -0.152}{sup +0.159}(stat){sub -0.123}{sup +0.107}(syst). Combining these new results with results of all other solar experiments and the KamLAND reactor experiment yields best-fit values of the mixing parameters of theta{sub 12}=34.06{sub -0.84}{sup +1.16} degrees and DELTAm{sub 21}{sup 2}=7.59{sub -0.21}{sup +0.20}x10{sup -5} eV{sup 2}. The global value of PHI{sup 8}{sub B} is extracted to a precision of {sub -2.95}{sup +2.38}%. In a three-flavor analysis the best fit value of sin{sup 2}theta{sub 13} is 2.00{sub -1.63}{sup +2.09}x10{sup -2}. This implies an upper bound of sin{sup 2}theta{sub 13}<0.057 (95% C.L.).
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