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A precise measurement of the atomic-mass dependence of dimuon production induced by 800-GeV protons is reported. Over 450000 muon pairs with dimuon mass A/> 4 GeV were recorded from targets of 2 H, C, Ca, Fe, and W. The ratio of dimuon yield per nucleon for nuclei versus 2 H, R ~YA/YI H , is sensitive to modifications of the antiquark sea in nuclei. No nuclear dependence of this ratio is observed over the range of target-quark momentum fraction 0.1

The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay -these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions.Experiments carried out over the past half century have revealed that neutrinos are found in three states, or flavors, and can transform from one flavor into another. These results indicate that each neutrino flavor state is a mixture of three different nonzero mass states, and to date offer the most compelling evidence for physics beyond the Standard Model. In a single experiment, LBNE will enable a broad exploration of the three-flavor model of neutrino physics with unprecedented detail. Chief among its potential discoveries is that of matter-antimatter asymmetries (through the mechanism of charge-parity violation) in neutrino flavor mixing -a step toward unraveling the mystery of matter generation in the early Universe. Independently, determination of the unknown neutrino mass ordering and precise measurement of neutrino mixing parameters by LBNE may reveal new fundamental symmetries of Nature.Grand Unified Theories, which attempt to describe the unification of the known forces, predict rates for proton decay that cover a range directly accessible with the next generation of large underground detectors such as LBNE's. The experiment's sensitivity to key proton decay channels will offer unique opportunities for the ground-breaking discovery of this phenomenon.Neutrinos emitted in the first few seconds of a core-collapse supernova carry with them the potential for great insight into the evolution of the Universe. LBNE's capability to collect and analyze this high-statistics neutrino signal from a supernova within our galaxy would provide a rare opportunity to peer inside a newly-formed neutron star and potentially witness the birth of a black hole.To achieve its goals, LBNE is conceived around three central components: (1) a new, highintensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a fine-grained near neutrino detector installed just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is ∼1,300 km from the neutrino source at Fermilab -a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions.With its exceptional combi...

The MiniBooNE experiment at Fermilab reports results from a search for ¯ν_{μ}→¯ν_{e} oscillations, using a data sample corresponding to 5.66×10²⁰ protons on target. An excess of 20.9±14.0 events is observed in the energy range 475

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Measurements of the ratio of Drell-Yan yields from an 800 GeV/c proton beam incident on liquid hydrogen and deuterium targets are reported. Approximately 360,000 Drell-Yan muon pairs remained after all cuts on the data. ¿From these data, the ratio of anti-down (d) to anti-up (ū) quark distributions in the proton sea is determined over a wide range in Bjorken-x. These results confirm previous measurements by E866 and extend them to lower x. From these data, (d −ū) and (d −ū)dx are evaluated for 0.015 < x < 0.35. These results are compared with parameterizations of various parton distribution functions, models and experimental results from NA51, NMC and HERMES. 13.85.Qk; 14.20.Dh; 24.85.+p; 14.65.Bt

We examine uncertainties in the analysis of the reactor neutrino anomaly, wherein it is suggested that only about 94% of the emitted antineutrino flux was detected in short baseline experiments. We find that the form of the corrections that lead to the anomaly are very uncertain for the 30% of the flux that arises from forbidden decays. This uncertainty was estimated in four ways, is larger than the size of the anomaly, and is unlikely to be reduced without accurate direct measurements of the antineutrino flux. Given the present lack of detailed knowledge of the structure of the forbidden transitions, it is not possible to convert the measured aggregate fission beta spectra to antineutrino spectra to the accuracy needed to infer an anomaly. Neutrino physics conclusions based on the original anomaly need to be revisited, as do oscillation analyses that assumed that the antineutrino flux is known to better than approximately 4%.The term "reactor neutrino anomaly" first appeared in a publication by G. Mention et al. [1], where it generally referred to the 3σ deficit of neutrinos detected in short-baseline reactor neutrino experiments relative to the number predicted. The predicted number of detected neutrinos has evolved upward over time, largely as a consequence of a predicted increase in the energy of the neutrino flux and an increasedν e + p → n + e + cross section associated with smaller values for the neutron lifetime. This cross section is used to infer the neutrino flux in a presumably well-characterized detector. The changes in the predicted neutrino flux are mostly associated with improved knowledge of the beta decays of the isotopes created in fission reactors. Such an anomaly would potentially be extremely significant, if a shortfall in the detected neutrino flux could be ascribed toν e oscillation into a light sterile neutrino with a mass of about 1 eV.There is an extensive recent literature dealing with the reactor anomaly, starting with a seminal paper by Mueller et al. [2] that reexamined the reactor antineutrino flux. The latter publication sought to improve the earlier flux estimates based on the ILL on-line measurements [3][4][5] of the integral beta spectrum of the fission products. An antineutrino spectrum can be inferred from a beta spectrum provided one knows the linear combination of operators involved in the decay, the end-point energy, and the nuclear charge. The fission beta spectra involve about 6000 beta transitions, of which about 1500 are forbidden [6]. Clearly some assumptions are required in order to infer the fission antineutrino flux. The improvements [1, 2] on the earlier analyses of ILL integral measurements led to an increased energy of the antineutrino flux, which was subsequently verified in an independent analysis [7].The present contribution examines the consequences of the forbidden transitions known to be present (at the 30% level) in the beta decay of fission products. We analyze the antineutrino flux, using a first-principles derivation of the finite size (FS) and weak ...

We find that firms protected by "second generation" state antitakeover laws substantially reduce their use of debt, and that unprotected firms do the reverse. This result supports recent models in which the threat of hostile takeover motivates managers to take on debt they would otherwise avoid. An implication is that legal barriers to takeovers may increase corporate slack.