1,537 research outputs found
The H Lyman- α emission line from the upper atmosphere of Jupiter: Parametric radiative transfer study and comparison with data
No full textInternational audienceThis study uses the adding-doubling radiative transfer method in which we take into account the curvature effect of the planetary atmosphere in order to test the sensitivity of the jovian Ly- α emission line in relation to H column density, eddy diffusion coefficient, frequency redistribution function for photon scattering, temperature vertical profile, and an added hot atomic H layer on the top of the atmosphere. We also focus here on developing new diagnostic tools that will help us to obtain more confidently the underlying thermospheric structure of Jupiter. First, using the brightness distribution for specific wavelength bands as proposed by Ben Jaffel et al. [Ben Jaffel, L., Magnan, C., Vidal-Madjar, A., 1988. Astron. Astrophys. 204, 319-326], we show that the spatial thickness of the atomic H layer above the homopause level can be measured directly as the separation between the vertical positions of respectively the line core and line wing optical limbs. This thickness also constrains the [H] column and the value K of the eddy diffusion coefficient at the homopause level at the disc location under consideration. We also propose to refine the value of K and [H], respectively, at a specific planetary latitude, using the Q ratio of the limb peak brightness to the intensity from other regions over the planetary disc. Finally, the relationship between the disc brightness distribution from specific wavelength bands of the emission line and the temperature gradient in the thermosphere is demonstrated, thus providing an accurate tool to access this key information from high resolution observations. Quick, preliminary comparisons with some existing HTS/STIS data show the H layer thickness at auroral latitudes ( ∼1700 km) is much smaller than at equatorial latitudes ( ∼3900 km). These results strongly support the existence of a gradient in both H density and K versus latitude, with higher values of K at high latitudes and higher values of the H density at the equatorial regions. Such a small H layer thickness at auroral latitudes is consistent with a high mixing in the atmosphere that brings the hydrocarbons upwards, reducing consequently the column of hydrogen that scatters photons. These preliminary results show the strength of the proposed approach and open new horizons to use strong resonant emission lines at high resolution as a diagnostic for the state and structure of planetary upper atmospheres
The Analysis of the H Lyman α Emission Line Profile from Jupiter's Aurora
No full textInternational audienceWe present the analysis and modeling of the emission spectra of the jovian northern auroral region taken from May 28 to June 3, 1993, with the Goddard High Resolution Spectrograph on board the Hubble Space Telescope. They extend from 1204 to 1240 Â covering H Lyman α and part of the Werner and the Lyman bands of H 2. We used the 2×2 arcsec large science aperture combined with the G160M grating (spectral resolution of 570 mÂ) centred on Jupiter's central meridian. The auroral region studied extends from 50 to 60° north latitudes and from 130 to 220° System III longitudes. Within the 1 arcsec pointing uncertainty, most of the region delineated by the theoretical ovals at 5.9 and 30 jovian radii (R J) in the VIP4 model of J. E. C. Connerney, M. H. Acuna, N. F. Ness, and T. Satoh (1998, New models of Jupiter's magnetic field constrained by the Io flux tube footprint. J. Geophys. Res. 103, 11,929-11,939), including the auroral oval derived from the Wide Field Planetary Camera 2 images by J. T. Clarke, G. E. Ballester, J. T. Trauger, R. Evans, J. E. P. Connerney, K. Stapelfeld, D. Crisp, P. D. Feldman, C. J. Burrows, S. Casertano, J. S. Gallagher, R. E. Griffiths, J. J. Hester, J. G. Hoessel, J. A. Holtzman, J. E. Krist, V. Meadows, J. R. Mould, P. A. Scowen, A. M. Watson, and J. A. Westphal (1996, Far-ultraviolet imaging of Jupiter's aurora and the Io "footprint". Science274, 404-409), was sampled. We derive auroral brightnesses (averaged over the slit) ranging from 20 kR in the 190-220° longitude region to 30 kR in the 130-160° longitude range. We use the theoretical model developed by D. Rego, R. Prangé, and L. Ben Jaffel (1999, Auroral Lyman α and H 2 bands from the giant planets. 3. Lyman α intensity and spectral profile including radiative effects and H 2 color ratios. J. Geophys. Res. Planets.104, 5939-5954), which calculates self-consistently the auroral Lyman α line profile for electron and proton precipitations and a given frequency redistribution function. This model shows that Lyman α profiles are not dependent upon the identity of the particles for a given penetration depth. These profiles only constrain the atmospheric H column density above the emitting layer, H col. Best agreement with the data is found with the complete frequency redistribution (CR). We derive an auroral H col of 1.3×10 16 cm -2 for all spectra with an upper limit of 5×10 16 cm -2. Precipitating protons also produce fast H atoms by charge exchange which can also be excited, but the resulting Doppler-shifted profile was not detected. Present data thus rule out protons as being the only precipitating particles. In the auroral zones, theoretical models predict that chemical reactions induced by particle precipitations often result in the production of atomic hydrogen, and thus an enhancement of the H density is expected. However, the value of H col we derive, between ∼8 and 23 times less than the equatorial values of L. Ben Jaffel, J. T. Clarke, R. Prangé, R. Gladstone, and A. Vidal-Madjar (1993, The Lyman alpha bulge of Jupiter: Effects of a non-thermal velocity field. J. Geophys. Res. Lett.20(8), 747-750), is in good agreement with the auroral values of R. Prangé, D. Rego, L. Pallier, L. Ben Jaffel, C. Emerich, J. T. Clarke, G. E. Ballester, and J. Ajello (1997, Detection of self-reversed Lyman α lines from the jovian aurorae with the Hubble space Telescope, Astrophys. J.484, L169-L173). This suggests that the H abundance predicted with standard atmospheric model is unrealistically large in the auroral region
Observation of the Λ b 0 → J / ψ Ξ - K + decay
No full textAbstract Using proton–proton collision data corresponding to an integrated luminosity of 140 fb - 1 collected by the CMS experiment at s = 13 Te V , the Λ b 0 → J / ψ Ξ - K + decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the Λ b 0 → ψ ( 2 S ) Λ decay, is measured to be B ( Λ b 0 → J / ψ Ξ - K + ) / B ( Λ b 0 → ψ ( 2 S ) Λ ) = [ 3.38 ± 1.02 ± 0.61 ± 0.03 ] % , where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in B ( ψ ( 2 S ) → J / ψ π + π - ) and B ( Ξ - → Λ π - )
Study of charm hadronization with prompt Λ c + baryons in proton-proton and lead-lead collisions at s NN = 5.02 TeV
No full textAbstract The production of prompt Λ c + baryons is measured via the exclusive decay channel Λ c + → p K − π + at a center-of-mass energy per nucleon pair of 5.02 TeV, using proton-proton (pp) and lead-lead (PbPb) collision data collected by the CMS experiment at the CERN LHC. The pp and PbPb data were obtained in 2017 and 2018 with integrated luminosities of 252 and 0.607 nb −1, respectively. The measurements are performed within the Λ c + rapidity interval |y| 10 GeV/c are strongly suppressed in PbPb collisions. The level of suppression depends significantly on the collision centrality. The Λ c + /D0 production ratio is similar in PbPb and pp collisions at p T > 10 GeV/c, suggesting that the coalescence process does not play a dominant role in prompt Λ c + baryon production at higher p T
Test of lepton flavor universality in B ± → K ± μ + μ − and B ± → K ± e + e − decays in proton-proton collisions at s = 13 TeV
No full textA test of lepton flavor universality inB±→K±μ+μ-andB±→K±e+e-decays, as well as a measurement of differential and integrated branching fractions of a nonresonantB±→K±μ+μ-decay are presented. The analysis is made possible by a dedicated data set of proton-proton collisions ats=13TeVrecorded in 2018, by the CMS experiment at the LHC, using a special high-rate data stream designed for collecting about 10 billion unbiased b hadron decays. The ratio of the branching fractionsB(B±→K±μ+μ-)toB(B±→K±e+e-)is determined from the measured double ratioR(K)of these decays to the respective branching fractions of theB±→J/ψK±withJ/ψ→μ+μ-ande+e-decays, which allow for significant cancellation of systematic uncertainties. The ratioR(K)is measured in the range1.1<6.0GeV2, whereqis the invariant mass of the lepton pair, and is found to beR(K)=0.78-0.23+0.47, in agreement with the standard model expectationR(K)≈1. This measurement is limited by the statistical precision of the electron channel. The integrated branching fraction in the sameq2range,B(B±→K±μ+μ-)=(12.42±0.68)×10-8, is consistent with the present world-average value and has a comparable precision
Observation of the Λb0→J/ψΞ-K+ decay
No full textUsing proton–proton collision data corresponding to an integrated luminosity of 140fb-1 collected by the CMS experiment at s=13TeV, the Λb0→J/ψΞ-K+ decay is observed for the first time, with a statistical significance exceeding 5 standard deviations. The relative branching fraction, with respect to the Λb0→ψ(2S)Λ decay, is measured to be B(Λb0→J/ψΞ-K+)/B(Λb0→ψ(2S)Λ)=[3.38±1.02±0.61±0.03]%, where the first uncertainty is statistical, the second is systematic, and the third is related to the uncertainties in B(ψ(2S)→J/ψπ+π-) and B(Ξ-→Λπ-)
Constraints on the Higgs Boson Self-coupling From the Combination of Single and Double Higgs Boson Production in Proton-proton Collisions at √s=13 Tev
No full textThe Higgs boson (H) trilinear self-coupling, lambda(3), is constrained via its measured properties and limits on the HH pair production using the proton-proton collision data collected by the CMS experiment at root s = 13 TeV. The combination of event categories enriched in single-H and HH events is used to measure k(lambda), defined as the value of lambda(3) normalized to its standard model prediction, while simultaneously constraining the Higgs boson couplings to fermions and vector bosons. Values of k(lambda) outside the interval -1.2 < k(lambda) < 7.5 are excluded at 2 sigma confidence level, which is compatible with the expected range of -2.0< k(lambda) < 7.7 under the assumption that all other Higgs boson couplings are equal to their standard model predicted values. Relaxing the assumption on the Higgs couplings to fermions and vector bosons the observed (expected) k(lambda) interval is constrained to be within -1.4 < k(lambda) < 7.8 (-2.3 < k(lambda) < 7.8) at 2 sigma confidence level.LPHE-L
Author Correction: A portrait of the Higgs boson by the CMS experiment ten years after the discovery
No full textIn the version of this article initially published, CMS Collaboration author names, affiliations and acknowledgements were omitted and have now been included in the HTML and PDF versions of the articl
Space Telescope detection of oxygen in the atmosphere of exoplanet HD 189733b
No full textDetecting heavy atoms in the inflated atmospheres of giant exoplanets that orbit close to their parent stars is a key factor for understanding their bulk composition, their evolution, and the processes that drive their expansion and interaction with the impinging stellar wind. Unfortunately, very few detections have been made thus far. Here, we use archive data obtained with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope to report an absorption of ~6.4% ± 1.8% by neutral oxygen during the HD 189733b transit. Using published results from a simple hydrodynamic model of HD 189733b, and assuming a mean temperature of ~(8−12) × 103 K for the upper atmosphere of the exoplanet, a mean vertical integrated O I density column of ~8 × 1015 cm-2 produces only a 3.5% attenuation transit. Much like the case of the hot-Jupiter HD 209458b, super-solar abundances and/or super-thermal broadening of the absorption lines are required to fit the deep transit drop-off observed in most far-ultraviolet lines. We also report evidence of short-time variability in the measured stellar flux, a variability that we analyze using time series derived from the time-tagged exposures, which we then compare to solar flaring activity. In that frame, we find that non-statistical uncertainties in the measured fluxes are not negligible, which calls for caution when reporting transit absorptions. Despite cumulative uncertainties that originate from variability in the stellar and sky background signals and in the instrument response, we also show a possible detection for both a transit and early-ingress absorption in the ion C II 133.5 nm lines. If confirmed, this would be the second exoplanet for which an early ingress absorption is reported. In contrast, such an early ingress signature is not detected for neutral O I. Assuming the HD 189733b magnetosphere to be at the origin of the early absorption, we use the Parker model for the stellar wind and a particle-in-cell code for the magnetosphere to show that its orientation should be deflected ~10−30° from the planet-star line, while its nose’s position should be at least ~16.7 Rp upstream of the exoplanet in order to fit the C II transit light curve. The derived stand-off distance is consistent with a surface magnetic field strength of ~5.3 Gauss for the exoplanet, and a supersonic stellar wind impinging at ~250 km s-1, with a temperature of 1.2 × 105 K and a density ~6.3 × 106 cm-3 at the planetary orbit, yet the fit is not unique
Measurement of the double-differential inclusive jet cross section in proton-proton collisions at s = 5.02 TeV
No full textAbstract The inclusive jet cross section is measured as a function of jet transverse momentum p T and rapidity y. The measurement is performed using proton-proton collision data at s = 5.02 TeV, recorded by the CMS experiment at the LHC, corresponding to an integrated luminosity of 27.4 pb −1. The jets are reconstructed with the anti-k T algorithm using a distance parameter of R = 0.4, within the rapidity interval |y| < 2, and across the kinematic range 0.06 < p T < 1 TeV. The jet cross section is unfolded from detector to particle level using the determined jet response and resolution. The results are compared to predictions of perturbative quantum chromodynamics, calculated at both next-to-leading order and next-to-next-to-leading order. The predictions are corrected for nonperturbative effects, and presented for a variety of parton distribution functions and choices of the renormalization/factorization scales and the strong coupling α S
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