25,018 research outputs found
Quantum anti-quenching of radiation from laser-driven structured plasma channels
We demonstrate that in the interaction of a high-power laser pulse with a
structured solid-density plasma-channel, clear quantum signatures of stochastic
radiation emission manifest, disclosing a novel avenue to studying the
quantized nature of photon emission. In contrast to earlier findings we observe
that the total radiated energy for very short interaction times, achieved by
studying thin plasma channel targets, is significantly larger in a quantum
radiation model as compared to a calculation including classical radiation
reaction, i.e., we observe quantum anti-quenching. By means of a detailed
analytical analysis and a refined test particle model, corroborated by a full
kinetic plasma simulation, we demonstrate that this counter-intuitive behavior
is due to the constant supply of energy to the setup through the driving laser.
We comment on an experimental realization of the proposed setup, feasible at
upcoming high-intensity laser facilities, since the required thin targets can
be manufactured and the driving laser pulses provided with existing technology.Comment: 6 pages, 3 figure
Strong energy enhancement in a laser-driven plasma-based accelerator through stochastic friction
Conventionally, friction is understood as an efficient dissipation mechanism
depleting a physical system of energy as an unavoidable feature of any
realistic device involving moving parts, e.g., in mechanical brakes. In this
work, we demonstrate that this intuitive picture loses validity in nonlinear
quantum electrodynamics, exemplified in a scenario where spatially random
friction counter-intuitively results in a highly directional energy flow. This
peculiar behavior is caused by radiation friction, i.e., the energy loss of an
accelerated charge due to the emission of radiation. We demonstrate
analytically and numerically how radiation friction can enhance the performance
of a specific class of laser-driven particle accelerators. We find the
unexpected directional energy boost to be due to the particles' energy being
reduced through friction whence the driving laser can accelerate them more
efficiently. In a quantitative case we find the energy of the laser-accelerated
particles to be enhanced by orders of magnitude.Comment: 14 pages, 3 figure
Breaking scale invariance from a singular inflaton potential
In this paper we break the scale invariance of the primordial power spectrum
of curvature perturbations of inflation. Introducing a singular behaviour due
to spontaneous symmetry breaking in the inflaton potential, we obtain fully
analytic expressions of scale dependent oscillation and a modulation in power
on small scale in the primordial spectrum. And we give the associated cosmic
microwave background and matter power spectra which we can observe now and
discuss the signature of the scale dependence. We also address the possibility
of whether some inflationary model with featured potential might mimic the
predictions of the scale invariant power spectrum. We present some examples
which illustrate such degeneracies.Comment: 20 pages, 9 figures; Discussion expanded and references added;
Miscellaneous typos correcte
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