Jurnal Edukasi
Not a member yet
4879 research outputs found
Sort by
Minimal mass blow up solutions for a double power nonlinear Schrödinger equation
No full textInternational audienceWe consider a nonlinear Schrödinger equation with double power nonlinearity, where one power is focusing and mass critical and the other mass sub-critical. Classical variational arguments ensure that initial data with mass less than the mass of the ground state of the mass critical problem lead to global in time solutions. We are interested by the threshold dynamic and in particular by the existence of finite time blow up minimal solutions. For the mass critical problem, such an object exists thanks to the explicit conformal symmetry, and is in fact unique. For the focusing double power nonlinearity, we exhibit a new class of minimal blow up solutions with blow up rates deeply affected by the double power nonlinearity. The analysis adapts the recent approach developed by Raphaël and Szeftel for the construction of minimal blow up elements
An upper bound on the number of rational points of arbitrary projective varieties over finite fields
No full textInternational audienceWe give an upper bound on the number of rational points of an arbitrary Zariski closed subset of a projective space over a finite field. This bound depends only on the dimensions and degrees of the irreducible components and holds for very general varieties, even reducible and non equidimensional. As a consequence, we prove a conjecture of Ghorpade and Lachaud on the maximal number of rational points of an equidimensional projective variety
The Dynamical Manin-Mumford Problem for Plane Polynomial Automorphisms
No full textInternational audienceLet f be a polynomial automorphism of the affine plane. In this paper we consider the possibility for it to possess infinitely many periodic points on an algebraic curve C. We conjecture that this hap- pens if and only if f admits a time-reversal symmetry; in particular the Jacobian Jac(f) must be a root of unity. As a step towards this conjecture, we prove that its Jacobian, together with all its Galois conjugates lie on the unit circle in the complex plane. Under mild additional assumptions we are able to conclude that indeed Jac(f) is a root of unity. We use these results to show in various cases that any two automor- phisms sharing an infinite set of periodic points must have a common it- erate, in the spirit of recent results by Baker-DeMarco and Yuan-Zhang
Measurement of the charge asymmetry in top quark pair production in pp collisions at sqrt(s) = 8 TeV using a template method
No full textSubmitted to Phys. Rev. D, see paper for full list of authorsInternational audienceThe charge asymmetry in the production of top quark and antiquark pairs is measured in proton-proton collisions at a center-of-mass energy of 8 TeV. The data, corresponding to an integrated luminosity of 19.6 inverse femtobarns, were collected by the CMS experiment at the LHC. Events with a single isolated electron or muon, and four or more jets, at least one of which is likely to have originated from hadronization of a bottom quark, are selected. A template technique is used to measure the asymmetry in the distribution of differences in the top quark and antiquark absolute rapidities. The measured asymmetry is A[c,y] = [0.33 +/- 0.26 (stat) +/- 0.33 (syst)]%, which is the most precise result to date. The results are compared to calculations based on the standard model and on several beyond-the-standard-model scenarios
Neutrino Physics with JUNO
No full text222 Pages, 147 figures - See paper for full list of authorsInternational audienceThe Jiangmen Underground Neutrino Observatory (JUNO), a 20 kton multi-purpose underground liquid scintillator detector, was proposed with the determination of the neutrino mass hierarchy as a primary physics goal. It is also capable of observing neutrinos from terrestrial and extra-terrestrial sources, including supernova burst neutrinos, diffuse supernova neutrino background, geoneutrinos, atmospheric neutrinos, solar neutrinos, as well as exotic searches such as nucleon decays, dark matter, sterile neutrinos, etc. We present the physics motivations and the anticipated performance of the JUNO detector for various proposed measurements. By detecting reactor antineutrinos from two power plants at 53-km distance, JUNO will determine the neutrino mass hierarchy at a 3-4 sigma significance with six years of running. The measurement of antineutrino spectrum will also lead to the precise determination of three out of the six oscillation parameters to an accuracy of better than 1\%. Neutrino burst from a typical core-collapse supernova at 10 kpc would lead to ~5000 inverse-beta-decay events and ~2000 all-flavor neutrino-proton elastic scattering events in JUNO. Detection of DSNB would provide valuable information on the cosmic star-formation rate and the average core-collapsed neutrino energy spectrum. Geo-neutrinos can be detected in JUNO with a rate of ~400 events per year, significantly improving the statistics of existing geoneutrino samples. The JUNO detector is sensitive to several exotic searches, e.g. proton decay via the decay channel. The JUNO detector will provide a unique facility to address many outstanding crucial questions in particle and astrophysics. It holds the great potential for further advancing our quest to understanding the fundamental properties of neutrinos, one of the building blocks of our Universe
Search for a massive resonance decaying into a Higgs boson and a W or Z boson in hadronic final states in proton-proton collisions at sqrt(s) = 8 TeV
No full textSubmitted to JHEP, see paper for full list of authorsInternational audienceA search for a massive resonance decaying into a standard-model-like Higgs boson (H) and a W or Z boson is reported. The analysis is performed on a data sample corresponding to an integrated luminosity of 19.7 inverse femtobarns, collected in proton-proton collisions at a centre-of-mass energy of 8 TeV with the CMS detector at the LHC. Signal events, in which the decay products of Higgs, W, or Z bosons at high Lorentz boost are contained within single reconstructed jets, are identified using jet substructure techniques, including the tagging of b hadrons. This is the first search for heavy resonances decaying into HW or HZ resulting in an all-jet final state, as well as the first application of jet substructure techniques to identify H to WW* to 4q decays at high Lorentz boost. No significant signal is observed and limits are set at 95% confidence level on the production cross section of W' and Z' in a model with mass-degenerate charged and neutral spin-1 resonances. Resonance masses are excluded for W' in the interval [1.0, 1.6] TeV, for Z' in the intervals [1.0, 1.1] and [1.3,1.5] TeV, and for mass-degenerate W' and Z' in the interval [1.0, 1.7] TeV
Heisenberg symmetry and hypermultiplet manifolds
No full textInternational audienceWe study the emergence of Heisenberg (Bianchi II) algebra in hyper-K\"ahler and quaternionic spaces. This is motivated by the r\^ole these spaces with this symmetry play in N=2 hypermultiplet scalar manifolds. We show how to construct related pairs of hyper-K\"ahler and quaternionic spaces under general symmetry assumptions, the former being a zooming-in limit of the latter at vanishing cosmological constant. We further apply this method for the two hyper-K\"ahler spaces with Heisenberg algebra, which is reduced to U(1)×U(1) at the quaternionic level. We also show that no quaternionic spaces exist with a strict Heisenberg symmetry -- as opposed to Heisenberg⋉U(1). We finally discuss the realization of the latter by gauging appropriate Sp(2,4) generators in N=2 conformal supergravity
Reconstruction of flux and altitude of volcanic SO<sub>2</sub> emissions from satellite observations: implications for volcanological and atmospherical studies.
No full textInternational audienceVolcanic sulphur dioxide (SO2) degassing is a crucial indicator of the sub-surface volcanic activity, which is widely used today for volcano monitoring and hazard assessment purposes. Volcanic SO2 is also important regarding atmospherical studies. More easily detectable from space, SO2 can be used as a proxy of the presence of ash to anticipate air traffic issues caused by explosive eruptions. Moreover, volcanic SO2 strongly impacts air quality but also climate following its conversion to radiatively-active sulphate aerosols. However, the accurate assessment of these various impacts is currently hampered by the poor knowledge of volcanic SO2 emissions, which can substantially vary with time, in terms of flux and altitude.To fulfil this need, we propose a strategy relying on satellite observations, which consequently allows for monitoring the eruptive activity of any remote volcano. The method consists in assimilating snapshots of the SO2 load, provided by infrared or ultraviolet satellite observations, in an inversion scheme that involves the use of a chemistry-transport model to describe the dispersion of SO2 released in the atmosphere. Applied on Eyjafjalla- jökull (Iceland) and Etna (Italy) eruption case-studies, this procedure allows for retrospectively reconstructing both the flux and altitude of the SO2 emissions with an hourly resolution. We show the improvement gained in the simulations and forecasts of the location and mass load of volcanic SO2 clouds using such a detailed reconstruction of emissions.For calibration-validation purpose, we compared our satellite-derived time-series of the SO2 flux with ground- based observations available on Etna. This comparison indicates a good agreement during ash-poor phases of the eruption. However, large discrepancies are observed during the ash-rich paroxysmal phase as a result of enhanced plume opacity affecting ground-based ultraviolet spectroscopic retrievals. Therefore, the SO2 emission rate derived from the ground is underestimated by almost one order of magnitude. This result calls for the necessity to revisit currently available inventories of the global budget of sulfur released by volcanoes, because they heavily rely on ground-based observations. It also shows that volcano observatories cannot rely solely on ground-based spectroscopical observations for the monitoring of ash-rich explosive eruptions
BanditRepair: Speculative Exploration of Runtime Patches
No full textWe propose, BanditRepair, a system that systematically explores and assesses a set of possible runtime patches. The system is grounded on so-called bandit algorithms, that are online machine learning algorithms, designed for constantly balancing exploitation and exploration. BanditRepair's runtime patches are based on modifying the execution state for repairing null dereferences. BanditRepair constantly trades the ratio of automatically handled failures for searching for new runtime patches and vice versa. We evaluate the system with 16 null dereference field bugs, where BanditRepair identifies a total of 8460 different runtime patches, which are composed of 1 up to 8 decisions (execution modifications) taken in a row. We are the first to finely characterize the search space and the outcomes of runtime repair based on execution modification
Southern Tibetan Plateau ice core δ18O reflects abrupt shifts in atmospheric circulation in the late 1970s
No full textInternational audienceIce cores from the Tibetan Plateau provide high-resolution records of changes in the snow and ice isotopic composition. In the monsoon sector of southern Tibetan Plateau, their climatic interpretation has been controversial. Here, we present a new high-resolution δ18O record obtained from 2206 measurements performed at 2–3 cm depth resolution along a 55.1 m depth ice core retrieved from the Noijinkansang glacier (NK, 5950 m a.s.l.) that spans the period from 1864 to 2006 AD. The data are characterized by high δ18O values in the nineteenth century, 1910s and 1960s, followed by a drop in the late 1970s and a recent increasing trend. The comparison with regional meteorological data and with a simulation performed with the LMDZiso general circulation model leads to the attribution of the abrupt shift in the late 1970s predominantly to changes in regional atmospheric circulation, together with the impact of atmospheric temperature change. Correlation analyses suggest that the large-scale modes of variability (PDO and ENSO, i.e. Pacific Decadal Oscillation and El Nino-Southern Oscillation) play important roles in modulating NK δ18O changes. The NK δ18O minimum at the end of the 1970s coincides with a PDO phase shift, an inflexion point of the zonal index (representing the overall intensity of the surface westerly anomalies over middle latitudes) as well as ENSO, implying interdecadal modulation of the influence of the PDO/ENSO on the Indian monsoon on southern TP precipitation δ18O. While convective activity above North India controls the intra-seasonal variability of precipitation δ18O in southern TP, other processes associated with changes in large-scale atmospheric circulation act at the inter-annual scale