135 research outputs found
Energy Dissipation of Axionic Boson Stars in Magnetized Conducting Media
Axions are possible candidates of dark matter in the present Universe. They
have been argued to form axionic boson stars with small masses . Since they possess oscillating electric fields in a
magnetic field, they dissipate their energies in magnetized conducting media.
We show that colliding with a magnetized white dwarf, the axionic boson stars
dissipate their energies and heat the white dwarf. Consequently the white dwarf
cooled sufficiently can emit detectable amount of radiations with the
collision. Using a recent evaluation of the population of the white dwarfs as
candidates of MACHOs, we estimate the event rate of the collisions and obtain a
result that the rate is large to be detectable.Comment: Improved Englis
Spontaneous Breakdown of U(1) symmetry in DLCQ without Zero Mode
We show that the spontaneous breakdown of U(1) symmetry in a Higgs model can
be described in discretized light cone formulation even by neglecting zero
mode. We obtain correctly the energy of a ground state with the symmetry
breakdown. We also show explicitly the presence of a Goldstone mode and its
absence when the U(1) symmetry is gauged. In spite of obtaining the favorable
results, we lose a merit in the formulation without zero modes that a naive
Fock vacuum is the true ground state.Comment: 7 page
Classical and Quantum Decay of Oscillatons: Oscillating Self-Gravitating Real Scalar Field Solitons
The oscillating gravitational field of an oscillaton of finite mass M causes
it to lose energy by emitting classical scalar field waves, but at a rate that
is non-perturbatively tiny for small GMm, where m is the scalar field mass:
d(GM)/dt ~ -3797437.776333015 e^[-39.433795197160163/(GMm)]/(GMm)^2.
Oscillatons also decay by the quantum process of the annihilation of scalarons
into gravitons, which is only perturbatively small in GMm, giving by itself
d(GM)/dt ~ - 0.008513223934732692 G m^2 (GMm)^5. Thus the quantum decay is
faster than the classical one for Gmm < 39.4338/[ln(1/Gm^2)}-7ln(GMm)+19.9160].
The time for an oscillaton to decay away completely into free scalarons and
gravitons is ~ 2/(G^5 m^11) ~ 10^324 yr (1 meV/m)^11. Oscillatons of more than
one real scalar field of the same mass generically asymptotically approach a
static-geometry U(1) boson star configuration with GMm = GM_0 m, at the rate
d(GM/c^3)/dt ~ [(C/(GMm)^4)e^{-alpha/(GMm)}+Q(m/m_{Pl})^2(GMm)^3]
[(GMm)^2-(GM_0 m)^2], with GM_0 m depending on the magnitudes and relative
phases of the oscillating fields, and with the same constants C, alpha, and Q
given numerically above for the single-field case that is equivalent to GM_0 m
= 0.Comment: 75 pages, LaTe
PseudoSkyrmion Effects on Tunneling Conductivity in Coherent Bilayer Quantum Hall States at
We present a mechamism why interlayer tunneling conductivity in coherent
bilayer quantum Hall states at is anomalously large, but finite in the
recent experiment. According to the mechanism, pseudoSkyrmions causes the
finite conductivity, although there exists an expectation that dissipationless
tunneling current arises in the state. PseudoSkyrmions have an intrinsic
polarization field perpendicular to the layers, which causes the dissipation.
Using the mechanism we show that the large peak in the conductivity remains for
weak parallel magnetic field, but decay rapidly after its strength is beyond a
critical one, Tesla.Comment: 6 pages, no figure
An analytic study towards instabilities of the glasma
Strong longitudinal color flux fields will be created in the initial stage of
high-energy nuclear collisions. We investigate analytically time evolution of
such boost-invariant color fields from Abelian-like initial conditions, and
next examine stability of the boost-invariant configurations against rapidity
dependent fluctuations. We find that the magnetic background field has an
instability induced by the lowest Landau level whose amplitude grows
exponentially. For the electric background field there is no apparent
instability although pair creations due to the Schwinger mechanism should be
involved.Comment: 4p, 3figs; poster contribution to QM200
Once again on electromagnetic properties of a domain wall interacting with charged fermions
The response to a magnetic flux is considered of the vacuum state of charged
Dirac fermions interacting with a domain wall made of a neutral spinless field
in (3+1) dimensions with the fermion mass having a phase variation across the
wall. It is pointed out that due to simple C parity arguments the spontaneous
magnetization for this system is necessarily zero, thus invalidating some
claims to the contrary in the literature. The cancellation of the spontaneous
magnetization is explicitly demonstrated in a particular class of models. The
same calculation produces a general formula for the electric charge density
induced by the magnetic flux -- an effect previously discussed in the
literature for axionic domain walls. The distribution of the induced charge is
calculated in specific models.Comment: 15 page
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