568 research outputs found
Lorentz transformation in Maxwell equations for slowly moving media
We use the method of field decomposition, a technique widely used in
relativistic magnetohydrodynamics, to study the small velocity approximation
(SVA) of the Lorentz transformation in Maxwell equations for slowly moving
media. The "deformed" Maxwell equations derived under the SVA in the lab frame
can be put into the conventional form of Maxwell equations in the medium's
comoving frame. Our results show that the Lorentz transformation in the SVA up
to ( is the speed of the medium and is the speed of light in
vacuum) is essential to derive these equations: the time and charge density
must also change when transforming to a different frame even in the SVA, not
just the position and current density as in the Galilean transformation. This
marks the essential difference of the Lorentz transformation from the Galilean
one. We show that the integral forms of Faraday and Ampere equations for slowly
moving surfaces are consistent with Maxwell equations. We also present Faraday
equation the covariant integral form in which the electromotive force can be
defined as a Lorentz scalar independent of the observer's frame. No evidences
exist to support an extension or modification of Maxwell equations.Comment: 16 pages, 1 figure, 3 tables. Section VI is added about integral
forms of Faraday and Ampere laws for moving surfaces. Part of Section IV and
V are rewitte
Lepton pair photoproduction in peripheral relativistic heavy-ion collisions
We study the lepton pair photoproduction in peripheral heavy-ion collisions
based on the formalism in our previous work [Phys. Rev. D 104, 056011 (2021)].
We present the numerical results for the distributions of the transverse
momentum, azimuthal angle and invariant mass for and
pairs as functions of the impact parameter and other kinematic
variables in Au+Au collisions. Our calculation incorporates the information on
the transverse momentum and polarization of photons which is essential to
describe the experimental data. We observe a broadening effect in the
transverse momentum for lepton pairs with and without smear effects. We also
observe a significant enhancement in the distribution of for
pairs. Our results provide a baseline for future studies of
other higher order corrections beyond Born approximation and medium effects in
the lepton pair production.Comment: 19 pages, 10 figure
Photoproduction of in peripheral isobar collisions
We investigate the photoproduction of di-electrons in peripheral collisions
of and
at 200 GeV. With the charge and
mass density distributions given by the calculation of the density functional
theory, we calculate the spectra of transverse momentum, invariant mass and
azimuthal angle for di-electrons at 40-80\% centrality. The ratios of these
spectra in Ru+Ru collisions over to Zr+Zr collisions are shown to be smaller
than (the ratio of for Ru and Zr) at low transverse
momentum. The deviation arises from the different mass and charge density
distributions in Ru and Zr. So the photoproduction of di-leptons in isobar
collisions may provide a new way to probe the nuclear structure.Comment: 17 pages, 6 figure
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