72 research outputs found
A 'moment-conserving' reformulation of GW theory
We show how to construct an effective Hamiltonian whose dimension scales
linearly with system size, and whose eigenvalues systematically approximate the
excitation energies of theory. This is achieved by rigorously expanding
the self-energy in order to exactly conserve a desired number of
frequency-independent moments of the self-energy dynamics. Recasting in
this way admits a low-scaling approach to build this
Hamiltonian, with a proposal to reduce this further to . This
relies on exposing a novel recursive framework for the density response moments
of the random phase approximation (RPA), where the efficient calculation of its
starting point mirrors the low-scaling approaches to compute RPA correlation
energies. The frequency integration of which distinguishes so many
different variants can be performed directly and cheaply in this moment
representation. Furthermore, the solution to the Dyson equation can be
performed exactly, avoiding analytic continuation, diagonal approximations or
iterative solutions to the quasiparticle equation, with the full-frequency
spectrum of all solutions obtained in a complete diagonalization of this
effective static Hamiltonian. We show how this approach converges rapidly with
respect to the order of the conserved self-energy moments, and is applied
across the benchmark dataset to obtain accurate spectra in
comparison to traditional implementations. We also show the ability to
systematically converge all-electron full-frequency spectra and high-energy
features beyond frontier excitations, as well as avoiding discontinuities in
the spectrum which afflict many other approaches
Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus.
Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability
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Search for the disappearance of muon antineutrinos in the NuMI neutrino beam
We report constraints on antineutrino oscillation parameters that were obtained by using the two MINOS detectors to measure the 7% muon antineutrino component of the NuMI neutrino beam. In the Far Detector, we select 130 events in the charged-current muon antineutrino sample, compared to a prediction of 136.4 ± 11.7(stat)^(+10.2)_(-8.9)(syst) events under the assumption │Δm^2│ = 2.32 X 10^(-3) eV^2, sin^2(2θ) = 1.0
An improved measurement of muon antineutrino disappearance in MINOS
We report an improved measurement of muon anti-neutrino disappearance over a
distance of 735km using the MINOS detectors and the Fermilab Main Injector
neutrino beam in a muon anti-neutrino enhanced configuration. From a total
exposure of 2.95e20 protons on target, of which 42% have not been previously
analyzed, we make the most precise measurement of the anti-neutrino
"atmospheric" delta-m squared = 2.62 +0.31/-0.28 (stat.) +/- 0.09 (syst.) and
constrain the anti-neutrino atmospheric mixing angle >0.75 (90%CL). These
values are in agreement with those measured for muon neutrinos, removing the
tension reported previously.Comment: 5 pages, 4 figures. In submission to Phys.Rev.Let
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Measurement of the Neutrino Mass Splitting and Flavor Mixing by MINOS
Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of 7.25×10^(20) protons on target. A fit to neutrino oscillations yields values of |Δm^2|=(2.32_(-0.08)^(+0.12))×10^(-3)  eV^2 for the atmospheric mass splitting and sin^2(2θ)>0.90 (90% C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively
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First Direct Observation of Muon Antineutrino Disappearance
This Letter reports the first direct observation of muon antineutrino disappearance. The MINOS experiment has taken data with an accelerator beam optimized for ν̅ _μ production, accumulating an exposure of 1.71×10^(20) protons on target. In the Far Detector, 97 charged current ν̅ _μ events are observed. The no-oscillation hypothesis predicts 156 events and is excluded at 6.3σ. The best fit to oscillation yields |Δm̅ 2|= [3.36=_(-0.40)^(+0.46)(stat)±0.06(syst)]x10^(-3)eV^2,sin^2(2θ̅)=0.86 _(-0.12)^(+0.11)(stat)±0.01(syst). The MINOS ν̅ _μ and ν̅ _μ measurements are consistent at the 2.0% confidence level, assuming identical underlying oscillation parameters
Measurement of the neutrino mass splitting and flavor mixing by MINOS
Measurements of neutrino oscillations using the disappearance of muon neutrinos from the Fermilab NuMI neutrino beam as observed by the two MINOS detectors are reported. New analysis methods have been applied to an enlarged data sample from an exposure of protons on target. A fit to neutrino oscillations yields values of ,eV for the atmospheric mass splitting and m sin^2!(2 heta) > 0.90 (90%,C.L.) for the mixing angle. Pure neutrino decay and quantum decoherence hypotheses are excluded at 7 and 9 standard deviations, respectively
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Improved Search for Muon-Neutrino to Electron-Neutrino Oscillations in MINOS
We report the results of a search for ν_e appearance in a ν_μ beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of 8.2×10^(20) protons on the NuMI target at Fermilab, we find 2sin^2(θ_(23))sin^2(2θ_(13))<0.12(0.20) at 90% confidence
level for δ=0 and the normal (inverted) neutrino mass hierarchy, with a best-fit of 2sin^2(θ_(23))sin^2(2θ_(13))=0.041^(+0.047)_(-0.031)(0.079^(+0.071)_(-0.053).
The θ_(13)= 0 hypothesis is disfavored by the MINOS data
at the 89% confidence level
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Active to Sterile Neutrino Mixing Limits from Neutral-Current Interactions in MINOS
Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of 7.07×10^(20) protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of 754±28(stat)±37(syst) for oscillations among three active flavors. The fraction f_s of disappearing ν_μ that may transition to ν_s is found to be less than 22% at the 90% C.L
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New constraints on muon-neutrino to electron-neutrino transitions in MINOS
This paper reports results from a search for ν_μ → ν_e transitions by the MINOS experiment based on a 7×10^(20) protons-on-target exposure. Our observation of 54 candidate ν_e events in the far detector with a background of 49.1±7.0(stat)±2.7(syst) events predicted by the measurements in the near detector requires 2sin^2(2θ_(13))sin^2θ_(23)<0.12(0.20) at the 90% C.L. for the normal (inverted) mass hierarchy at δ_(CP)=0. The experiment sets the tightest limits to date on the value of θ_(13) for nearly all values of δ_(CP) for the normal neutrino mass hierarchy and maximal sin^2(2θ_(23))
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