Author
Sacha E Kopp
Other affiliations: University at Albany, SUNY, University of Chicago, Syracuse University
Bio: Sacha E Kopp is an academic researcher from University of Texas at Austin. The author has contributed to research in topics: Neutrino & NuMI. The author has an hindex of 59, co-authored 351 publications receiving 13449 citations. Previous affiliations of Sacha E Kopp include University at Albany, SUNY & University of Chicago.
Topics: Neutrino, NuMI, Fermilab, MINOS, Neutrino oscillation
Papers published on a yearly basis
Papers
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TL;DR: In this paper, the existence of the top quark was established using a data sample of collisions at the Fermilab National Ensemble (CDF) collected with the Collider Detector.
Abstract: We establish the existence of the top quark using a $67{\mathrm{pb}}^{\ensuremath{-}1}$ data sample of $\overline{p}p$ collisions at $\sqrt{s}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1.8\mathrm{TeV}$ collected with the Collider Detector at Fermilab (CDF). Employing techniques similar to those we previously published, we observe a signal consistent with $t\overline{t}$ decay to $\mathrm{WWb}\overline{b}$, but inconsistent with the background prediction by $4.8\ensuremath{\sigma}$. Additional evidence for the top quark is provided by a peak in the reconstructed mass distribution. We measure the top quark mass to be $176\ifmmode\pm\else\textpm\fi{}8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}10(\mathrm{syst})\mathrm{GeV}{/c}^{2}$, and the $t\overline{t}$ production cross section to be ${6.8}_{\ensuremath{-}2.4}^{+3.6}\mathrm{pb}$.
1,022 citations
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Fermilab1, University of Sussex2, Argonne National Laboratory3, University of Oxford4, University of Minnesota5, Brookhaven National Laboratory6, University of Cambridge7, University of Texas at Austin8, Harvard University9, Tufts University10, State University of Campinas11, Indiana University12, University of Pittsburgh13, University College London14, College of the Holy Cross15, Universidade Federal de Goiás16, University of São Paulo17, Illinois Institute of Technology18, University of Warsaw19, California Institute of Technology20, Stanford University21
TL;DR: The results of a search for ν(e) appearance in a ν (μ) beam in the MINOS long-baseline neutrino experiment find that 2 sin(2) (θ(23))sin(2)(2θ (13))<0.12 at 90% confidence level for δ = 0 and the normal (inverted) neutrinos mass hierarchy.
Abstract: 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 that 2 sin(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(-0.031)(+0.047) (0.079(-0.053) (+0.071)). The θ(13) = 0 hypothesis is disfavored by the MINOS data at the 89% confidence level.
730 citations
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TL;DR: In this article, the MINOS experiment reported results from its initial exposure to neutrinos from the Fermilab NuMI beam, and the rate and energy spectra of charged current muon neutrino interactions are compared in two detectors located along the beam axis at distances of 1 km and 735 km.
Abstract: This letter reports results from the MINOS experiment based on its initial exposure to neutrinos from the Fermilab NuMI beam. The rate and energy spectra of charged current muon neutrino interactions are compared in two detectors located along the beam axis at distances of 1 km and 735 km. With 1.27 x 10^{20} 120 GeV protons incident on the NuMI target, 215 events with energies below 30 GeV are observed at the Far Detector, compared to an expectation of 336 \\\\\\\\\\\\\\\\pm 14.4 events. The data are consistent with muon neutrino disappearance via oscillation with |\\\\\\\\\\\\\\\\Delta m^2_{23}| = 2.74^{+0.44}_{-0.26} x 10^{-3} eV^2/c^4 and sin^2(2\\\\\\\\\\\\\\\\theta_{23}) > 0.87 (at 60% C.L.).
517 citations
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Purdue University1, University of Rochester2, Southern Methodist University3, Syracuse University4, University of Texas at Austin5, University of Texas–Pan American6, Vanderbilt University7, Virginia Tech8, Wayne State University9, California Institute of Technology10, University of California, San Diego11, University of California, Santa Barbara12, Carnegie Mellon University13, Cornell University14, University of Florida15, Harvard University16, University of Illinois at Urbana–Champaign17, Carleton University18, Ithaca College19, University of Kansas20, University of Minnesota21, University at Albany, SUNY22, Ohio State University23, University of Oklahoma24, University of Pittsburgh25
TL;DR: In this paper, the authors measured the branching fraction and photon energy spectrum for the radiative penguin process b-->s gamma, and obtained the first and second moments of the photon spectrum above 2.0 GeV.
Abstract: We have measured the branching fraction and photon energy spectrum for the radiative penguin process b-->s gamma. We find Beta(b-->s gamma) = (3.21+/-0.43+/-0.27(+0.18)(-0.10))x10(-4), where the errors are statistical, systematic, and from theory corrections. We obtain first and second moments of the photon energy spectrum above 2.0 GeV, = 2.346+/-0.032+/-0.011 GeV, and - (2) = 0.0226+/-0.0066+/-0.0020 GeV(2), where the errors are statistical and systematic. From the first moment, we obtain (in the modified minimal subtraction renormalization scheme, to order 1/M(3)(B) and beta(0)alpha(2)(s)) the heavy quark effective theory parameter Lambda = 0.35+/-0.08+/-0.10 GeV.
425 citations
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TL;DR: Using the CLEO II detector, the authors measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons {pi}{sup 0, {eta, and {eta}{prime}.
Abstract: Using the CLEO II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons {pi}{sup 0}, {eta}, and {eta}{prime}. From our measurements we have obtained the form factors associated with the electromagnetic transitions {gamma}*{gamma} {yields} meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV2 for {pi}{sup 0}, {eta}, and {eta}{prime}, respectively, and have made comparisons to various theoretical predictions.
396 citations
Cited by
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TL;DR: This biennial Review summarizes much of particle physics, using data from previous editions.
12,798 citations
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TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These
9,929 citations
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TL;DR: The Pythia program as mentioned in this paper can be used to generate high-energy-physics ''events'' (i.e. sets of outgoing particles produced in the interactions between two incoming particles).
Abstract: The Pythia program can be used to generate high-energy-physics ''events'', i.e. sets of outgoing particles produced in the interactions between two incoming particles. The objective is to provide as accurate as possible a representation of event properties in a wide range of reactions, within and beyond the Standard Model, with emphasis on those where strong interactions play a role, directly or indirectly, and therefore multihadronic final states are produced. The physics is then not understood well enough to give an exact description; instead the program has to be based on a combination of analytical results and various QCD-based models. This physics input is summarized here, for areas such as hard subprocesses, initial- and final-state parton showers, underlying events and beam remnants, fragmentation and decays, and much more. Furthermore, extensive information is provided on all program elements: subroutines and functions, switches and parameters, and particle and process data. This should allow the user to tailor the generation task to the topics of interest.
6,300 citations
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TL;DR: In this article, the Wilkinson Microwave Anisotropy Probe (WMAP) 5-year data were used to constrain the physics of cosmic inflation via Gaussianity, adiabaticity, the power spectrum of primordial fluctuations, gravitational waves, and spatial curvature.
Abstract: The Wilkinson Microwave Anisotropy Probe (WMAP) 5-year data provide stringent limits on deviations from the minimal, six-parameter Λ cold dark matter model. We report these limits and use them to constrain the physics of cosmic inflation via Gaussianity, adiabaticity, the power spectrum of primordial fluctuations, gravitational waves, and spatial curvature. We also constrain models of dark energy via its equation of state, parity-violating interaction, and neutrino properties, such as mass and the number of species. We detect no convincing deviations from the minimal model. The six parameters and the corresponding 68% uncertainties, derived from the WMAP data combined with the distance measurements from the Type Ia supernovae (SN) and the Baryon Acoustic Oscillations (BAO) in the distribution of galaxies, are: Ω b h 2 = 0.02267+0.00058 –0.00059, Ω c h 2 = 0.1131 ± 0.0034, ΩΛ = 0.726 ± 0.015, ns = 0.960 ± 0.013, τ = 0.084 ± 0.016, and at k = 0.002 Mpc-1. From these, we derive σ8 = 0.812 ± 0.026, H 0 = 70.5 ± 1.3 km s-1 Mpc–1, Ω b = 0.0456 ± 0.0015, Ω c = 0.228 ± 0.013, Ω m h 2 = 0.1358+0.0037 –0.0036, z reion = 10.9 ± 1.4, and t 0 = 13.72 ± 0.12 Gyr. With the WMAP data combined with BAO and SN, we find the limit on the tensor-to-scalar ratio of r 1 is disfavored even when gravitational waves are included, which constrains the models of inflation that can produce significant gravitational waves, such as chaotic or power-law inflation models, or a blue spectrum, such as hybrid inflation models. We obtain tight, simultaneous limits on the (constant) equation of state of dark energy and the spatial curvature of the universe: –0.14 < 1 + w < 0.12(95%CL) and –0.0179 < Ω k < 0.0081(95%CL). We provide a set of WMAP distance priors, to test a variety of dark energy models with spatial curvature. We test a time-dependent w with a present value constrained as –0.33 < 1 + w 0 < 0.21 (95% CL). Temperature and dark matter fluctuations are found to obey the adiabatic relation to within 8.9% and 2.1% for the axion-type and curvaton-type dark matter, respectively. The power spectra of TB and EB correlations constrain a parity-violating interaction, which rotates the polarization angle and converts E to B. The polarization angle could not be rotated more than –59 < Δα < 24 (95% CL) between the decoupling and the present epoch. We find the limit on the total mass of massive neutrinos of ∑m ν < 0.67 eV(95%CL), which is free from the uncertainty in the normalization of the large-scale structure data. The number of relativistic degrees of freedom (dof), expressed in units of the effective number of neutrino species, is constrained as N eff = 4.4 ± 1.5 (68%), consistent with the standard value of 3.04. Finally, quantitative limits on physically-motivated primordial non-Gaussianity parameters are –9 < f local NL < 111 (95% CL) and –151 < f equil NL < 253 (95% CL) for the local and equilateral models, respectively.
5,904 citations
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TL;DR: The current status of particle dark matter, including experimental evidence and theoretical motivations, including direct and indirect detection techniques, is discussed in this paper. But the authors focus on neutralinos in models of supersymmetry and Kaluza-Klein dark matter in universal extra dimensions.
4,614 citations