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Hiu Paus Arungi Lautan Sejauh 17.000 Km dalam Dua Minggu
Dalam dua minggu, hiu paus mampu menempuh jarak 17.000 kilometer, menyelam hingga kedalaman 1.800 meter.
¿Fotos de gigantescas naves extraterrestres cerca del Sol? La NASA no 'vuela' tan alto
Las imágenes del Sol obtenidas por el satélite de la NASA Solar Dynamics Observatory (SDO) y el observatorio solar Solar and Heliospheric Observatory, están dando que hablar. Uno de los últimos casos discutido en la Red, según se hace eco 'RT', data de los pasados 22 y 27 de agosto. En la imagen captada por el satélite SOHO se puede apreciar una forma [...]
Unbroken B-L Symmetry. (arXiv:1408.6845v1 [hep-ph])

The difference between baryon number B and lepton number L is the only anomaly-free global symmetry of the Standard Model, easily promoted to a local symmetry by introducing three right-handed neutrinos, which automatically make neutrinos massive. The non-observation of any (B-L)-violating processes leads us to scrutinize the case of unbroken gauged B-L; besides Dirac neutrinos, the model contains only three parameters, the gauge coupling strength g', the Stueckelberg mass $M_{Z'}$, and the kinetic mixing angle $chi$. The new force could manifest itself at any scale, and we collect and derive bounds on g' over the entire testable range $M_{Z'}$ = 0 - $10^{13}$ eV, also of interest for the more popular case of spontaneously broken B-L or other new light forces. We show in particular that successful Big Bang nucleosynthesis provides strong bounds for masses 10 eV < $M_{Z'}$ < 10 GeV due to resonant enhancement of the rate $overline{f} f leftrightarrow overline{nu}_R nu_R$. The strongest limits typically arise from astrophysics and colliders, probing scales $M_{Z'}/g'$ from TeV up to $10^{10}$ GeV.

Performance of cryogenic charge readout electronics with the ARGONTUBE LAr TPC. (arXiv:1408.7046v1 [physics.ins-det])

ARGONTUBE is a liquid argon time projection chamber (TPC) with an electron drift length of up to 5 m equipped with cryogenic charge-sensitive preamplifiers. In this work, we present results on its performance including a comparison of the new cryogenic charge-sensitive preamplifiers with the previously used room-temperature-operated charge preamplifiers.

Physics with boosted top quarks. (arXiv:1408.7007v1 [hep-ex])

The production at the LHC of boosted top quarks (top quarks with a transverse momentum that greatly exceeds their rest mass) is a promising process to search for phenomena beyond the Standard Model. In this contribution several examples are discussed of new techniques to reconstruct and identify (tag) the collimated decay topology of the boosted hadronic decays of top quarks. Boosted top reconstruction techniques have been utilized in searches for new physical phenomena. An overview is given of searches by ATLAS, CDF and CMS for heavy new particles decaying into a top and an anti-top quark, vector-like quarks and supersymmetric partners to the top quark.

Measurement of the direct CP-violating parameter A_CP in the decay D+ -> K- pi+ pi+. (arXiv:1408.6848v1 [hep-ex])

We measure the direct CP-violating parameter A_CP for the decay of the charged charm meson, D+ -> K-pi+pi+ (and charge conjugate), using the full 10.4 fb-1 sample of ppbar collisions at sqrt(s) = 1.96 TeV collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from B -> D processes) using input from Monte Carlo simulation. We measure A_CP = [-0.16 +- 0.15 (stat.) +- 0.09 (syst.)]%, which is consistent with zero, as expected from the standard model prediction of CP conservation, and is the most precise measurement of this quantity to date

Proceeding for LHCP2014 Poster: Search for direct pair production of the top squark in all-hadronic final states in proton-proton collisions at $sqrt{s}=8$ TeV with the ATLAS detector. (arXiv:1408.6975v1 [hep-ex])

The results of a search for direct pair production of the scalar partner to the top quark using an integrated luminosity of $20.1 rm{fb}^{-1}$ of proton-proton collision data at $sqrt{s}=8$ TeV recorded with the ATLAS detector at the LHC are reported. The top squark is assumed to decay via $tilde{t} rightarrow t tilde{chi}_{1}^{0}$ or $tilde{t}rightarrow btilde{chi}_{1}^{pm} rightarrow b W^{left(astright)} tilde{chi}_{1}^{0}$, where $tilde{chi}_{1}^{0}$ ($tilde{chi}_{1}^{pm}$) denotes the lightest neutralino (chargino) in supersymmetric models. The search targets a fully-hadronic final state in events with four or more jets and large missing transverse momentum. No significant excess over the Standard Model background prediction is observed, and exclusion limits are reported in terms of the top squark and neutralino masses and as a function of the branching fraction of $tilde{t} rightarrow t tilde{chi}_{1}^{0}$. For a branching fraction of 100%, top squark masses in the range 270-645 GeV are excluded for $tilde{chi}_{1}^{0}$ masses below 30 GeV. For a branching fraction of 50% to either $tilde{t} rightarrow t tilde{chi}_{1}^{0}$ or $tilde{t}rightarrow btilde{chi}_{1}^{pm}$, and assuming the $tilde{chi}_{1}^{pm}$ mass to be twice the $tilde{chi}_{1}^{0}$ mass, top squark masses in the range 250-550 GeV are excluded for $tilde{chi}_{1}^{0}$ masses below 60 GeV.

The LHC data and an upper bound for the inelastic diffraction. (arXiv:1408.6946v1 [hep-ph])

We comment on the status of the Pumplin bound for the inelastic diffraction in the light of the recent LHC data for elastic scattering

Handling uncertainties in background shapes: the discrete profiling method. (arXiv:1408.6865v1 [physics.data-an])

A common problem in high energy physics is the extraction of a signal over a potentially large background. In cases where the functional form of the background is not a priori known, then some extra uncertainty must be assigned to the signal parameters because of this lack of knowledge. A method for assigning an error from this cause is presented. It is based on treating the lack of knowledge of the functional form as a discrete nuisance parameter which is profiled in an equivalent way to continuous nuisance parameters. This effectively means an "envelope" is found which encompasses the lowest log-likelihood values for any given signal parameter. The bias and coverage of this method are shown to be good when applied to a realistic example.

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