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N. Wadia

Bio: N. Wadia is an academic researcher from Louisiana State University. The author has contributed to research in topics: Center (category theory) & Neutrino oscillation. The author has an hindex of 14, co-authored 17 publications receiving 3537 citations.

Papers
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Journal ArticleDOI
TL;DR: The LSND data suggest that neutrino oscillations occur in the $0.2 -10 -10 range as discussed by the authors, which is consistent with other known limits on neutrinos oscillations.
Abstract: A search for ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{ u}}}_{e}$ oscillations was conducted by the Liquid Scintillator Neutrino Detector at the Los Alamos Neutron Science Center using ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}$ from ${\ensuremath{\mu}}^{+}$ decay at rest. A total excess of $87.9\ifmmode\pm\else\textpm\fi{}22.4\ifmmode\pm\else\textpm\fi{}6.0$ events consistent with ${\overline{\ensuremath{ u}}}_{e}\stackrel{\ensuremath{\rightarrow}}{p}{e}^{+}n$ scattering was observed above the expected background. This excess corresponds to an oscillation probability of $(0.264\ifmmode\pm\else\textpm\fi{}0.067\ifmmode\pm\else\textpm\fi{}0.045)%,$ which is consistent with an earlier analysis. In conjunction with other known limits on neutrino oscillations, the LSND data suggest that neutrino oscillations occur in the $0.2--10 {\mathrm{eV}}^{2}{/c}^{4} \ensuremath{\Delta}{m}^{2}$ range, indicating a neutrino mass greater than $0.4 \mathrm{eV}{/c}^{2}.$

1,261 citations

Journal ArticleDOI
TL;DR: In this paper, a search for oscillations at the Los Alamos Meson Physics Facility was conducted by using the decay at rest of the decay decay decay at the LAMF.
Abstract: A search for ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{ u}}}_{e}$ oscillations has been conducted at the Los Alamos Meson Physics Facility by using ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}$ from ${\ensuremath{\mu}}^{+}$ decay at rest. The ${\overline{\ensuremath{ u}}}_{e}$ are detected via the reaction ${\overline{\ensuremath{ u}}}_{e}p\ensuremath{\rightarrow}{e}^{+}n$, correlated with a $\ensuremath{\gamma}$ from $\mathrm{np}\ensuremath{\rightarrow}d\ensuremath{\gamma}$ ( $2.2\mathrm{MeV}$). The use of tight cuts to identify ${e}^{+}$ events with correlated $\ensuremath{\gamma}$ rays yields 22 events with ${e}^{+}$ energy between 36 and $60\mathrm{MeV}$ and only $4.6\ifmmode\pm\else\textpm\fi{}0.6$ background events. A fit to the ${e}^{+}$ events between 20 and $60\mathrm{MeV}$ yields a total excess of ${51.0}_{\ensuremath{-}19.5}^{+20.2}\ifmmode\pm\else\textpm\fi{}8.0$ events. If attributed to ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{ u}}}_{e}$ oscillations, this corresponds to an oscillation probability of ( $0.31\ifmmode\pm\else\textpm\fi{}0.12\ifmmode\pm\else\textpm\fi{}0.05$)%.

584 citations

Journal ArticleDOI
TL;DR: In this paper, a beam-on high-energy (60-200 MeV) electron event was observed consistent with the observed oscillation probability of $(2.6\ifmmode\pm\else\textpm\fi{}1.0
Abstract: A search for ${\ensuremath{ u}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\ensuremath{ u}}_{e}$ oscillations has been conducted with the LSND apparatus using ${\ensuremath{ u}}_{\ensuremath{\mu}}$ from ${\ensuremath{\pi}}^{+}$ decay in flight. Two analyses observe a total of 40 beam-on high-energy (60--200 MeV) electron events consistent with the ${\ensuremath{ u}}_{e}\mathrm{C}\ensuremath{\rightarrow}{e}^{\ensuremath{-}}X$ inclusive reaction. This number is significantly above the $21.9\ifmmode\pm\else\textpm\fi{}2.1$ events expected from the ${\ensuremath{ u}}_{e}$ contamination in the beam and the beam-off background. If interpreted as an oscillation signal, the observed oscillation probability of $(2.6\ifmmode\pm\else\textpm\fi{}1.0\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ is consistent with the previously reported ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{ u}}}_{e}$ oscillation evidence from LSND.

468 citations

Journal ArticleDOI
TL;DR: In this paper, a search for nu_mu -> nu_e oscillations has been conducted with the LSND apparatus at the Los Alamos Meson Physics Facility, using nu_me from pi+ decay in flight, the nu_eme appearance is detected via the charged-current reaction C(nu_e,e^-)X.
Abstract: A search for nu_mu -> nu_e oscillations has been conducted with the LSND apparatus at the Los Alamos Meson Physics Facility. Using nu_mu from pi^+ decay in flight, the nu_e appearance is detected via the charged-current reaction C(nu_e,e^-)X. Two independent analyses observe a total of 40 beam-on high-energy electron events (60 nu_e_bar oscillation evidence from LSND.

438 citations

Journal ArticleDOI
TL;DR: The cross section of the elastic scattering reaction was measured by the Liquid Scintillator Neutrino Detector using a decay-at-rest beam at the Los Alamos Neutron Science Center as mentioned in this paper.
Abstract: The cross section for the elastic scattering reaction ${\ensuremath{ u}}_{e}{+e}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{ u}}_{e}{+e}^{\ensuremath{-}}$ was measured by the Liquid Scintillator Neutrino Detector using a ${\ensuremath{\mu}}^{+}$ decay-at-rest ${\ensuremath{ u}}_{e}$ beam at the Los Alamos Neutron Science Center. The standard model of electroweak physics predicts a large destructive interference between the charge current and neutral current channels for this reaction. The measured cross section, ${\ensuremath{\sigma}}_{{\ensuremath{ u}}_{e}{e}^{\ensuremath{-}}}=[10.1\ifmmode\pm\else\textpm\fi{}1.1(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{E}_{{\ensuremath{ u}}_{e}}(\mathrm{MeV})\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}45}{\mathrm{cm}}^{2},$ agrees well with standard model expectations. The measured value of the interference parameter, $I=\ensuremath{-}1.01\ifmmode\pm\else\textpm\fi{}0.13(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.12(\mathrm{syst}),$ is in good agreement with the standard model expectation of ${I}^{\mathrm{SM}}=\ensuremath{-}1.09.$ Limits are placed on neutrino flavor-changing neutral currents. An upper limit on the muon-neutrino magnetic moment of $6.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}{\ensuremath{\mu}}_{\mathrm{Bohr}}$ is obtained using the ${\ensuremath{ u}}_{\ensuremath{\mu}}$ and ${\overline{\ensuremath{ u}}}_{\ensuremath{\mu}}$ fluxes from ${\ensuremath{\pi}}^{+}$ and ${\ensuremath{\mu}}^{+}$ decay.

255 citations


Cited by
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Journal ArticleDOI
Nabila Aghanim1, Yashar Akrami2, Yashar Akrami3, Yashar Akrami4  +229 moreInstitutions (70)
TL;DR: In this article, the authors present cosmological parameter results from the full-mission Planck measurements of the cosmic microwave background (CMB) anisotropies, combining information from the temperature and polarization maps and the lensing reconstruction.
Abstract: We present cosmological parameter results from the final full-mission Planck measurements of the cosmic microwave background (CMB) anisotropies, combining information from the temperature and polarization maps and the lensing reconstruction Compared to the 2015 results, improved measurements of large-scale polarization allow the reionization optical depth to be measured with higher precision, leading to significant gains in the precision of other correlated parameters Improved modelling of the small-scale polarization leads to more robust constraints on manyparameters,withresidualmodellinguncertaintiesestimatedtoaffectthemonlyatthe05σlevelWefindgoodconsistencywiththestandard spatially-flat6-parameter ΛCDMcosmologyhavingapower-lawspectrumofadiabaticscalarperturbations(denoted“base ΛCDM”inthispaper), from polarization, temperature, and lensing, separately and in combination A combined analysis gives dark matter density Ωch2 = 0120±0001, baryon density Ωbh2 = 00224±00001, scalar spectral index ns = 0965±0004, and optical depth τ = 0054±0007 (in this abstract we quote 68% confidence regions on measured parameters and 95% on upper limits) The angular acoustic scale is measured to 003% precision, with 100θ∗ = 10411±00003Theseresultsareonlyweaklydependentonthecosmologicalmodelandremainstable,withsomewhatincreasederrors, in many commonly considered extensions Assuming the base-ΛCDM cosmology, the inferred (model-dependent) late-Universe parameters are: HubbleconstantH0 = (674±05)kms−1Mpc−1;matterdensityparameterΩm = 0315±0007;andmatterfluctuationamplitudeσ8 = 0811±0006 We find no compelling evidence for extensions to the base-ΛCDM model Combining with baryon acoustic oscillation (BAO) measurements (and consideringsingle-parameterextensions)weconstraintheeffectiveextrarelativisticdegreesoffreedomtobe Neff = 299±017,inagreementwith the Standard Model prediction Neff = 3046, and find that the neutrino mass is tightly constrained toPmν < 012 eV The CMB spectra continue to prefer higher lensing amplitudesthan predicted in base ΛCDM at over 2σ, which pulls some parameters that affect thelensing amplitude away from the ΛCDM model; however, this is not supported by the lensing reconstruction or (in models that also change the background geometry) BAOdataThejointconstraintwithBAOmeasurementsonspatialcurvatureisconsistentwithaflatuniverse, ΩK = 0001±0002Alsocombining with Type Ia supernovae (SNe), the dark-energy equation of state parameter is measured to be w0 = −103±003, consistent with a cosmological constant We find no evidence for deviations from a purely power-law primordial spectrum, and combining with data from BAO, BICEP2, and Keck Array data, we place a limit on the tensor-to-scalar ratio r0002 < 006 Standard big-bang nucleosynthesis predictions for the helium and deuterium abundances for the base-ΛCDM cosmology are in excellent agreement with observations The Planck base-ΛCDM results are in good agreement with BAO, SNe, and some galaxy lensing observations, but in slight tension with the Dark Energy Survey’s combined-probe results including galaxy clustering (which prefers lower fluctuation amplitudes or matter density parameters), and in significant, 36σ, tension with local measurements of the Hubble constant (which prefer a higher value) Simple model extensions that can partially resolve these tensions are not favoured by the Planck data

4,688 citations

Journal ArticleDOI
Nabila Aghanim1, Yashar Akrami2, Yashar Akrami3, Yashar Akrami4  +229 moreInstitutions (70)
TL;DR: In this paper, the cosmological parameter results from the final full-mission Planck measurements of the CMB anisotropies were presented, with good consistency with the standard spatially-flat 6-parameter CDM cosmology having a power-law spectrum of adiabatic scalar perturbations from polarization, temperature, and lensing separately and in combination.
Abstract: We present cosmological parameter results from the final full-mission Planck measurements of the CMB anisotropies. We find good consistency with the standard spatially-flat 6-parameter $\Lambda$CDM cosmology having a power-law spectrum of adiabatic scalar perturbations (denoted "base $\Lambda$CDM" in this paper), from polarization, temperature, and lensing, separately and in combination. A combined analysis gives dark matter density $\Omega_c h^2 = 0.120\pm 0.001$, baryon density $\Omega_b h^2 = 0.0224\pm 0.0001$, scalar spectral index $n_s = 0.965\pm 0.004$, and optical depth $\tau = 0.054\pm 0.007$ (in this abstract we quote $68\,\%$ confidence regions on measured parameters and $95\,\%$ on upper limits). The angular acoustic scale is measured to $0.03\,\%$ precision, with $100\theta_*=1.0411\pm 0.0003$. These results are only weakly dependent on the cosmological model and remain stable, with somewhat increased errors, in many commonly considered extensions. Assuming the base-$\Lambda$CDM cosmology, the inferred late-Universe parameters are: Hubble constant $H_0 = (67.4\pm 0.5)$km/s/Mpc; matter density parameter $\Omega_m = 0.315\pm 0.007$; and matter fluctuation amplitude $\sigma_8 = 0.811\pm 0.006$. We find no compelling evidence for extensions to the base-$\Lambda$CDM model. Combining with BAO we constrain the effective extra relativistic degrees of freedom to be $N_{\rm eff} = 2.99\pm 0.17$, and the neutrino mass is tightly constrained to $\sum m_ u< 0.12$eV. The CMB spectra continue to prefer higher lensing amplitudes than predicted in base -$\Lambda$CDM at over $2\,\sigma$, which pulls some parameters that affect the lensing amplitude away from the base-$\Lambda$CDM model; however, this is not supported by the lensing reconstruction or (in models that also change the background geometry) BAO data. (Abridged)

3,077 citations

Journal ArticleDOI
TL;DR: In this article, the authors give simple mass-matrices leading to tri-bimaximal mixing, and discuss its relation to the Fritzsch-Xing democratic ansatz.

1,347 citations

Journal ArticleDOI
TL;DR: In this article, the authors combine the constraints from the recent Ly$\ensuremath{\alpha}$ forest analysis of the Sloan Digital Sky Survey (SDSS) and the SDSS galaxy bias analysis with previous constraints from sDSS galaxies clustering, the latest supernovae, and 1st year WMAP cosmic microwave background anisotropies, and find significant improvements on all of the cosmological parameters compared to previous constraints.
Abstract: We combine the constraints from the recent Ly$\ensuremath{\alpha}$ forest analysis of the Sloan Digital Sky Survey (SDSS) and the SDSS galaxy bias analysis with previous constraints from SDSS galaxy clustering, the latest supernovae, and 1st year WMAP cosmic microwave background anisotropies. We find significant improvements on all of the cosmological parameters compared to previous constraints, which highlights the importance of combining Ly$\ensuremath{\alpha}$ forest constraints with other probes. Combining WMAP and the Ly$\ensuremath{\alpha}$ forest we find for the primordial slope ${n}_{s}=0.98\ifmmode\pm\else\textpm\fi{}0.02$. We see no evidence of running, $dn/d\mathrm{ln} k=\ensuremath{-}0.003\ifmmode\pm\else\textpm\fi{}0.010$, a factor of $3$ improvement over previous constraints. We also find no evidence of tensors, $rl0.36$ ($95%$ c.l.). Inflationary models predict the absence of running and many among them satisfy these constraints, particularly negative curvature models such as those based on spontaneous symmetry breaking. A positive correlation between tensors and primordial slope disfavors chaotic inflation-type models with steep slopes: while the $V\ensuremath{\propto}{\ensuremath{\phi}}^{2}$ model is within the 2-sigma contour, $V\ensuremath{\propto}{\ensuremath{\phi}}^{4}$ is outside the 3-sigma contour. For the amplitude we find ${\ensuremath{\sigma}}_{8}=0.90\ifmmode\pm\else\textpm\fi{}0.03$ from the Ly$\ensuremath{\alpha}$ forest and WMAP alone. We find no evidence of neutrino mass: for the case of $3$ massive neutrino families with an inflationary prior, $\ensuremath{\sum}_{}^{}{m}_{\ensuremath{ u}}l0.42$ eV and the mass of lightest neutrino is ${m}_{1}l0.13$ eV at $95%$ c.l. For the 3 massless $+1$ massive neutrino case we find ${m}_{\ensuremath{ u}}l0.79$ eV for the massive neutrino, excluding at $95%$ c.l. all neutrino mass solutions compatible with the LSND results. We explore dark energy constraints in models with a fairly general time dependence of dark energy equation of state, finding ${\ensuremath{\Omega}}_{\ensuremath{\lambda}}=0.72\ifmmode\pm\else\textpm\fi{}0.02$, $\mathrm{w}(z=0.3)=\ensuremath{-}{0.98}_{\ensuremath{-}0.12}^{+0.10}$, the latter changing to $\mathrm{w}(z=0.3)=\ensuremath{-}{0.92}_{\ensuremath{-}0.10}^{+0.09}$ if tensors are allowed. We find no evidence for variation of the equation of state with redshift, $\mathrm{w}(z=1)=\ensuremath{-}{1.03}_{\ensuremath{-}0.28}^{+0.21}$. These results rely on the current understanding of the Ly$\ensuremath{\alpha}$ forest and other probes, which need to be explored further both observationally and theoretically, but extensive tests reveal no evidence of inconsistency among different data sets used here.

1,075 citations

Journal ArticleDOI
TL;DR: This review summarizes both the theoretical frameworks for tests of Lorentz invariance and experimental advances that have made new high precision tests possible.
Abstract: Motivated by ideas about quantum gravity, a tremendous amount of effort over the past decade has gone into testing Lorentz invariance in various regimes. This review summarizes both the theoretical frameworks for tests of Lorentz invariance and experimental advances that have made new high precision tests possible. The current constraints on Lorentz violating effects from both terrestrial experiments and astrophysical observations are presented.

1,008 citations