(Mis)Understanding the Atmospheric Neutrino Anomaly

The apparent attenuation of muon neutrinos relative to electron neutrinos is a bit too low to be compatible with the most popular values of $\Delta m^{2}$. Fits to $R(E_{\nu})$ favor values of $\Delta m^{2}>0.1$ eV$^{2}$. The fit minimized by the Super Kamioka group in estimating neutrino oscillation parameters neglects systematic errors. The fit is dominated by systematic effects. The data being combined in recent fits may not be compatible since there appear to be significant variations in the properties of the data with time. A simple two component neutrino oscillation with $\Delta m^{2}$ in the range of 10$^{-3}$ to 10$^{-2}$ eV$^{2}$ seems unable to account for the observations.Comment: 7 pages, 3 figures, talk given at the Sixth International Workshop on Tau Lepton Physics, Victoria, BC Canada, September 19, 200

Can a supernova be located by its neutrinos?

A future core-collapse supernova in our Galaxy will be detected by several neutrino detectors around the world. The neutrinos escape from the supernova core over several seconds from the time of collapse, unlike the electromagnetic radiation, emitted from the envelope, which is delayed by a time of order hours. In addition, the electromagnetic radiation can be obscured by dust in the intervening interstellar space. The question therefore arises whether a supernova can be located by its neutrinos alone. The early warning of a supernova and its location might allow greatly improved astronomical observations. The theme of the present work is a careful and realistic assessment of this question, taking into account the statistical significance of the various neutrino signals. Not surprisingly, neutrino-electron forward scattering leads to a good determination of the supernova direction, even in the presence of the large and nearly isotropic background from other reactions. Even with the most pessimistic background assumptions, SuperKamiokande (SK) and the Sudbury Neutrino Observatory (SNO) can restrict the supernova direction to be within circles of radius $5^\circ$ and $20^\circ$, respectively. Other reactions with more events but weaker angular dependence are much less useful for locating the supernova. Finally, there is the oft-discussed possibility of triangulation, i.e., determination of the supernova direction based on an arrival time delay between different detectors. Given the expected statistics we show that, contrary to previous estimates, this technique does not allow a good determination of the supernova direction.Comment: 11 pages including 2 figures. Revised version corrects typos, adds some brief comment

Search for Exotic Mesons in pi- P Interactions at 18 GeV/c

The recent search for non $q \bar{q}$ mesons in $\pi^{-}p$ interactions at Brookhaven National Laboratory is summarized. Many final states such as $\eta \pi$, $\eta' \pi^{-}$, $a_{0} \pi$, $f_{1} \pi$, $a_{2} \pi$, $b_{1} \pi$, which are favored decay modes of exotics, are under investigation.Comment: 9 pages, PostScript, Presented at the International School of Nuclear Physics, Erice, Sicily, Italy, September 199

Confirmation of a pi_1^0 Exotic Meson in the \eta \pi^0 System

The exclusive reaction $\pi^- p \to \eta \pi^0 n$, $\eta \to \pi^+ \pi^- \pi^0$ at 18 GeV$/c$ has been studied with a partial wave analysis on a sample of 23~492 $\eta \pi^0 n$ events from BNL experiment E852. A mass-dependent fit is consistent with a resonant hypothesis for the $P_+$ wave, thus providing evidence for a neutral exotic meson with $J^{PC} = 1^{-+}$, a mass of $1257 \pm 20 \pm 25$ MeV$/c^2$, and a width of $354 \pm 64 \pm 60$ MeV$/c^2$. New interpretations of the meson exotics in neutral $\eta \pi^0$ system observed in E852 and Crystal Barrel experiments are discussed.Comment: p3, rewording the paragraph (at the bottom) about the phase variations. p4, rewording paragrath "The second method ..." . p4, at the bottom of paragrath "The third method ..." added consistent with the results of methods 1 and 2

Exotic Meson Production in the f1(1285)π−f_{1}(1285)\pi^{-} System observed in the Reaction π−p→ηπ+π−π−p\pi^{-} p \to \eta\pi^{+}\pi^{-}\pi^{-} p at 18 GeV/c

This letter reports results from the partial wave analysis of the $\pi^{-}\pi^{-}\pi^{+}\eta$ final state in $\pi^{-}p$ collisions at 18GeV/c. Strong evidence is observed for production of two mesons with exotic quantum numbers of spin, parity and charge conjugation, $J^{PC} = 1^{-+}$ in the decay channel $f_{1}(1285)\pi^{-}$. The mass $M = 1709 \pm 24 \pm 41$ MeV/c^2 and width $\Gamma = 403 \pm 80 \pm 115$ MeV/c^2 of the first state are consistent with the parameters of the previously observed $\pi_{1}(1600)$. The second resonance with mass $M = 2001 \pm 30 \pm 92$ MeV/c^2 and width $\Gamma = 333 \pm 52 \pm 49$ MeV/c^2 agrees very well with predictions from theoretical models. In addition, the presence of $\pi_{2}(1900)$ is confirmed with mass $M = 2003 \pm 88 \pm 148$ MeV/c^2 and width $\Gamma = 306 \pm 132 \pm 121$ MeV/c^2 and a new state, $a_{1}(2096)$, is observed with mass $M = 2096 \pm 17 \pm 121$ MeV/c^2 and width $\Gamma = 451 \pm 41 \pm 81$ MeV/c^2. The decay properties of these last two states are consistent with flux tube model predictions for hybrid mesons with non-exotic quantum numbers

The angular distribution of the reaction νˉe+p→e++n\bar{\nu}_e + p \to e^+ + n

The reaction $\bar{\nu}_e + p \to e^+ + n$ is very important for low-energy ($E_\nu \lesssim 60$ MeV) antineutrino experiments. In this paper we calculate the positron angular distribution, which at low energies is slightly backward. We show that weak magnetism and recoil corrections have a large effect on the angular distribution, making it isotropic at about 15 MeV and slightly forward at higher energies. We also show that the behavior of the cross section and the angular distribution can be well-understood analytically for $E_\nu \lesssim 60$ MeV by calculating to ${\cal O}(1/M)$, where $M$ is the nucleon mass. The correct angular distribution is useful for separating $\bar{\nu}_e + p \to e^+ + n$ events from other reactions and detector backgrounds, as well as for possible localization of the source (e.g., a supernova) direction. We comment on how similar corrections appear for the lepton angular distributions in the deuteron breakup reactions $\bar{\nu}_e + d \to e^+ + n + n$ and $\nu_e + d \to e^- + p + p$. Finally, in the reaction $\bar{\nu}_e + p \to e^+ + n$, the angular distribution of the outgoing neutrons is strongly forward-peaked, leading to a measurable separation in positron and neutron detection points, also potentially useful for rejecting backgrounds or locating the source direction.Comment: 10 pages, including 5 figure

Observation of Pseudoscalar and Axial Vector Resonances in pi- p -> K+ K- pi0 n at 18 GeV

A new measurement of the reaction pi- p -> K+ K- pi0 n has been made at a beam energy of 18 GeV. A partial wave analysis of the K+ K- pi0 system shows evidence for three pseudoscalar resonances, eta(1295), eta(1416), and eta(1485), as well as two axial vectors, f1(1285), and f1(1420). Their observed masses, widths and decay properties are reported. No signal was observed for C(1480), an IG J{PC} = 1+ 1{--} state previously reported in phi pi0 decay.Comment: 7 pages, 6 figs, to be submitted to Phys. Let

Observation of a New J(PC)=1(+-) Isoscalar State in the Reaction Pi- Proton -> Omega Eta Neutron at 18 GeV/c

Results are presented on a partial wave analysis of the Omega Eta final state produced in Pi- Proton interactions at 18 GeVc where Omega -> Pi+ Pi- Pi0, Pi0 -> 2 Gammas, and Eta -> 2 Gammas. We observe the previously unreported decay mode Omega(1650) -> Omega Eta and a new 1(+-) meson state h1(1595) with a mass M=1594(15)(+10)(-60) MeV/c^2 and a width Gamma=384(60)(+70)(-100) MeV/c^2. The h1(1595) state exhibits resonant-like phase motion relative to the Omega(1650).Comment: Submitted to Physics Letters B Eight total pages including 11 figures and 1 tabl

Solar Neutrinos and the Principle of Equivalence

We study the proposed solution of the solar neutrino problem which requires a flavor nondiagonal coupling of neutrinos to gravity. We adopt a phenomenological point of view and investigate the consequences of the hypothesis that the neutrino weak interaction eigenstates are linear combinations of the gravitational eigenstates which have slightly different couplings to gravity, $f_1G$ and $f_2G$, $|f_1-f_2| << 1$, corresponding to a difference in red-shift between electron and muon neutrinos, $\Delta z/(1+z) \sim |f_1 - f_2|$. We perform a $\chi^2$ analysis of the latest available solar neutrino data and obtain the allowed regions in the space of the relevant parameters. The existing data rule out most of the parameter space which can be probed in solar neutrino experiments, allowing only $|f_1 - f_2| \sim 3 \times 10^{-14}$ for small values of the mixing angle ($2 \times 10^{-3} \le \sin^2(2\theta_G) \le 10^{-2}$) and $10^{-16} \stackrel{<}{\sim} |f_1 - f_2| \stackrel{<}{\sim}10^{-15}$ for large mixing ($0.6 \le \sin^2(2\theta_G) \le 0.9$). Measurements of the $^8{\rm B}$-neutrino energy spectrum in the SNO and Super-Kamiokande experiments will provide stronger constraints independent of all considerations related to solar models. We show that these measurements will be able to exclude part of the allowed region as well as to distinguish between conventional oscillations and oscillations due to the violation of the equivalence principle.Comment: 20 pages + 4 figures, IASSNS-AST 94/5

Indirect Neutralino Detection Rates in Neutrino Telescopes

Neutralinos annihilating in the center of the Sun or the Earth may give rise to a detectable signal of neutrinos. We derive the indirect detection rates for neutrino telescopes in the minimal supersymmetric extension of the standard model. We show that even after imposing all phenomenological and experimental constraints that make the theories viable, regions of parameter space exist which can already be probed by existing neutrino telescopes. We compare with the discovery potential of supersymmetry at LEP2 as well as direct detections and point out the complementarity of the methods.Comment: LaTeX, 18 pages with 9 eps-figure