5,795 research outputs found
The Structure of Martian Magnetosphere at the Dayside Terminator Region as Observed on MAVEN Spacecraft
We analyzed 44 passes of the MAVEN spacecraft through the magnetosphere,
arranged by the angle between electric field vector and the projection of
spacecraft position radius vector in the YZ plane in MSE coordinate system
( E ). All passes were divided into 3 angular sectors near 0{\deg},
90{\deg} and 180{\deg} E angles in order to estimate the role of IMF
direction in plasma and magnetic properties of dayside Martian magnetosphere.
The time interval chosen was from January 17 through February 4, 2016 when
MAVEN was crossing the dayside magnetosphere at SZA ~ 70{\deg}. Magnetosphere
as the region with prevailing energetic planetary ions is always found between
the magnetosheath and the ionosphere. 3 angular sectors of dayside interaction
region in MSE coordinate system with different orientation of the solar wind
electric field vector E = -1/c V x B showed that for each sector one can find
specific profiles of the magnetosheath, the magnetic barrier and the
magnetosphere. Plume ions originate in the northern MSE sector where motion
electric field is directed from the planet. This electric field ejects
magnetospheric ions leading to dilution of magnetospheric heavy ions
population, and this effect is seen in some magnetospheric profiles. Magnetic
barrier forms in front of the magnetosphere, and relative magnetic field
magnitudes in these two domains vary. The average height of the boundary with
ionosphere is ~530 km and the average height of the magnetopause is ~730 km. We
discuss the implications of the observed magnetosphere structure to the
planetary ions loss mechanism.Comment: 24 pages, 13 figure
Gradient soft magnetic materials produced by additive manufacturing from non-magnetic powders
The changes in the magnetic properties have been attributed to the formation of the BCC phase after mixing two FCC-dominated powders. Moreover, the phase composition of the obtained gradient materials can be predicted with reasonable accuracy by the CALPHAD approach, thus providing efficient optimization of the performance. The obtained results provide new prospects for printing gradient magnetic alloy
Titan's interaction with the supersonic solar wind
After 9 years in the Saturn system, the Cassini spacecraft finally observed Titan in the supersonic and super-AlfvĂŠnic solar wind. These unique observations reveal that Titan?s interaction with the solar wind is in many ways similar to unmagnetized planets Mars and Venus and active comets in spite of the differences in the properties of the solar plasma in the outer solar system. In particular, Cassini detected a collisionless, supercritical bow shock and a well-defined induced magnetosphere filled with mass-loaded interplanetary magnetic field lines, which drape around Titan?s ionosphere. Although the flyby altitude may not allow the detection of an ionopause, Cassini reports enhancements of plasma density compatible with plasma clouds or streamers in the flanks of its induced magnetosphere or due to an expansion of the induced magnetosphere. Because of the upstream conditions, these observations may be also relevant to other bodies in the outer solar system such as Pluto, where kinetic processes are expected to dominate.Fil: Bertucci, Cesar. Consejo Nacional de InvestigaciĂłnes CientĂficas y TĂŠcnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de AstronomĂa y FĂsica del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de AstronomĂa y FĂsica del Espacio; ArgentinaFil: Hamilton, D. C.. University of Maryland; Estados UnidosFil: Kurth, W. S.. University of Iowa; Estados UnidosFil: Hospodarsky, G.. University of Iowa; Estados UnidosFil: Mitchell, D.. University Johns Hopkins; Estados UnidosFil: Sergis, N.. Academy of Athens; GreciaFil: Edberg, N. J. T.. Swedish Institute of Space Physics,; SueciaFil: Dougherty, M. K.. Imperial College London; Reino Unid
Search for invisible decays of sub-GeV dark photons in missing-energy events at the CERN SPS
We report on a direct search for sub-GeV dark photons (A') which might be
produced in the reaction e^- Z \to e^- Z A' via kinetic mixing with photons by
100 GeV electrons incident on an active target in the NA64 experiment at the
CERN SPS. The A's would decay invisibly into dark matter particles resulting in
events with large missing energy. No evidence for such decays was found with
2.75\cdot 10^{9} electrons on target. We set new limits on the \gamma-A' mixing
strength and exclude the invisible A' with a mass < 100 MeV as an explanation
of the muon g_\mu-2 anomaly.Comment: 6 pages, 3 figures; Typos corrected, references adde
Phase diagrams in nonlocal PNJL models constrained by Lattice QCD results
Based on lattice QCD-adjusted SU(2) nonlocal Polyakov--Nambu--Jona-Lasinio
(PNJL) models, we investigate how the location of the critical endpoint in the
QCD phase diagram depends on the strenght of the vector meson coupling, as well
as the Polyakov-loop (PL) potential and the form factors of the covariant
model. The latter are constrained by lattice QCD data for the quark propagator.
The strength of the vector coupling is adjusted such as to reproduce the slope
of the pseudocritical temperature for the chiral phase transition at low
chemical potential extracted recently from lattice QCD simulations. Our study
supports the existence of a critical endpoint in the QCD phase diagram albeit
the constraint for the vector coupling shifts its location to lower
temperatures and higher baryochemical potentials than in the case without it.Comment: 23 pages, 10 figures. Version accepted in Phys. Part. Nucl. Lett. (to
appear), references adde
Measurement of the t t-bar production cross section in the dilepton channel in pp collisions at sqrt(s) = 7 TeV
The t t-bar production cross section (sigma[t t-bar]) is measured in
proton-proton collisions at sqrt(s) = 7 TeV in data collected by the CMS
experiment, corresponding to an integrated luminosity of 2.3 inverse
femtobarns. The measurement is performed in events with two leptons (electrons
or muons) in the final state, at least two jets identified as jets originating
from b quarks, and the presence of an imbalance in transverse momentum. The
measured value of sigma[t t-bar] for a top-quark mass of 172.5 GeV is 161.9 +/-
2.5 (stat.) +5.1/-5.0 (syst.) +/- 3.6(lumi.) pb, consistent with the prediction
of the standard model.Comment: Replaced with published version. Included journal reference and DO
Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV
A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay
channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7
TeV is presented. The data were collected at the LHC, with the CMS detector,
and correspond to an integrated luminosity of 4.6 inverse femtobarns. No
significant excess is observed above the background expectation, and upper
limits are set on the Higgs boson production cross section. The presence of the
standard model Higgs boson with a mass in the 270-440 GeV range is excluded at
95% confidence level.Comment: Submitted to JHE
Combined search for the quarks of a sequential fourth generation
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.Comment: Replaced with published version. Added journal reference and DO
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