Acceleration of solar wind particles due to inertial Alfvén waves

Gaining an understanding of the effects and dynamics of the solar wind is crucial for the study of space weather,Earth's magnetosphere,spacecraft protection,the dynamics of the Solar System,and various other subjects.Observations show that Alfvén waves effectively transfer energy to resonant particles.This study demonstrates how inertial Alfvén waves deliver their energy to resonant plasma particles in different solar environments under certain conditions.The analysis shows that inertial Alfvén waves experience more rapid damping with increasing parallel wavenumber,ambient magnetic field strength,and particle number density,coupled with a decrease in temperature.The rate of energy transfer to resonant particles intensifies with higher temperatures and reduced parallel wavenumber and particle number density.Particles with higher initial velocities actively participate in Landau damping,especially in regions with a stronger ambient magnetic field.

Development of plasma sources for Dipole Research EXperiment(DREX)

Dipole Research EXperiment（DREX） is a new terrella device as part of the Space Plasma Environment Research Facility（SPERF） for laboratory studies of space physics relevant to the inner magnetospheric plasmas. Adequate plasma sources are very important for DREX to achieve its scientific goals. According to different research requirements, there are two density regimes for DREX. The low density regime will be achieved by an electron cyclotron resonance（ECR） system for the ‘whistler/chorus＇ wave investigation, while the high density regime will be achieved by biased cold cathode discharge for the desired ‘Alfvén＇ wave study. The parameters of ‘whistler/chorus＇ waves and ‘Alfvén＇ waves are determined by the scaling law between space and laboratory plasmas in the current device. In this paper, the initial design of these two plasma sources for DREX is described. Focus is placed on the chosen frequency and operation mode of the ECR system which will produce relatively low density ‘artificial radiation belt＇ plasmas and the seed electrons, followed by the design of biased cold cathode discharge to generate plasma with high density.

Observation of structure in the J/ψ-pair mass spectrum

Using proton-proton collision data at centre-of-mass energies of and 13 TeV recorded by the LHCb experiment at the Large Hadron Collider,corresponding to an integrated luminosity of 9 fb-1,the invariant mass spectrum of J/ψ pairs is studied.A narrow structure around 6:9 GeV=c^2 matching the lineshape of a resonance and a broad structure just above twice the J/ψ mass are observed.The deviation of the data from nonresonant J/ψ-pair production is above five standard deviations in the mass region between 6:2 and 7:4 GeV=c^2,covering predicted masses of states composed of four charm quarks.The mass and natural width of the narrow X(6900)structure are measured assuming a Breit-Wigner lineshape.

Evidence of a J/ψΛstructure and observation of excited■^(-)states in the■b^(-)→J/ψΛK^(-) decay

First evidence of a structure in the J/ψΛinvariant mass distribution is obtained from an amplitude analysis of■b^(-)J/ψΛK^(-)decays.The observed structure is consistent with being due to a charmonium pentaquark with strangeness with a significance of 3.1r including systematic uncertainties and lookelsewhere effect.Its mass and width are determined to be 4458:8±2:9t4:7-1:1 MeV and 17:3±6:5t8:0-5:7 MeV,respectively,where the quoted uncertainties are statistical and systematic.The structure is also consistent with being due to two resonances.In addition,the narrow excited■^(-)states,N■(1690)and■(1820),are seen for the first time in a■b^(-)decay,and their masses and widths are measured with improved precision.The analysis is performed using pp collision data corresponding to a total integrated luminosity of 9 fb^(-1),collected with the LHCb experiment at centre-of-mass energies of 7,8 and 13 TeV.