14 research outputs found
The Fulling-Davies-Unruh Effect is Mandatory: The Proton's Testimony
We discuss the decay of accelerated protons and illustrate how the
Fulling-Davies-Unruh effect is indeed mandatory to maintain the consistency of
standard Quantum Field Theory. The confidence level of the Fulling-Davies-Unruh
effect must be the same as that of Quantum Field Theory itself.Comment: Awarded "honorable mention" by Gravity Research Foundation in the
2002 Essay competitio
Analytic Evaluation of the Decay Rate for Accelerated Proton
We evaluate the decay rate of the uniformly accelerated proton. We obtain an
analytic expression for inverse beta decay process caused by the acceleration.
We evaluate the decay rate both from the inertial frame and from the
accelerated frame where we should consider thermal radiation by Unruh effect.
We explicitly check that the decay rates obtained in both frame coincide with
each other.Comment: 11 page
Particle creation due to tachyonic instability in relativistic stars
Dense enough compact objects were recently shown to lead to an exponentially
fast increase of the vacuum energy density for some free scalar fields properly
coupled to the spacetime curvature as a consequence of a tachyonic-like
instability. Once the effect is triggered, the star energy density would be
overwhelmed by the vacuum energy density in a few milliseconds. This demands
that eventually geometry and field evolve to a new configuration to bring the
vacuum back to a stationary regime. Here, we show that the vacuum fluctuations
built up during the unstable epoch lead to particle creation in the final
stationary state when the tachyonic instability ceases. The amount of created
particles depends mostly on the duration of the unstable epoch and final
stationary configuration, which are open issues at this point. We emphasize
that the particle creation coming from the tachyonic instability will occur
even in the adiabatic limit, where the spacetime geometry changes arbitrarily
slowly, and therefore is quite distinct from the usual particle creation due to
the change in the background geometry.Comment: 12 pages, 2 figures, discussion improved: paragraph added at the end
of Sec. V B (published version
Awaking the vacuum in relativistic stars
Void of any inherent structure in classical physics, the vacuum has revealed
to be incredibly crowded with all sorts of processes in relativistic quantum
physics. Yet, its direct effects are usually so subtle that its structure
remains almost as evasive as in classical physics. Here, in contrast, we report
on the discovery of a novel effect according to which the vacuum is compelled
to play an unexpected central role in an astrophysical context. We show that
the formation of relativistic stars may lead the vacuum energy density of a
quantum field to an exponential growth. The vacuum-driven evolution which would
then follow may lead to unexpected implications for astrophysics, while the
observation of stable neutron-star configurations may teach us much on the
field content of our Universe.Comment: To appear in Phys. Rev. Let
Decay of accelerated protons and the existence of the Fulling-Davies-Unruh effect
We investigate the weak decay of uniformly {\em accelerated protons} in the
context of {\em standard} Quantum Field Theory. Because the mean {\em proper}
lifetime of a particle is a scalar, the same value for this observable must be
obtained in the inertial and coaccelerated frames. We are only able to achieve
this equality by considering the Fulling-Davies-Unruh effect. This reflects the
fact that the Fulling-Davies-Unruh effect is mandatory for the consistency of
Quantum Field Theory. There is no question about its existence provided one
accepts the validity of standard Quantum Field Theory in flat spacetime.Comment: 4 pages (revtex), 1 figure, to appear in Phys. Rev. Let
Can quantum mechanics fool the cosmic censor?
We revisit the mechanism for violating the weak cosmic-censorship conjecture
(WCCC) by overspinning a nearly-extreme charged black hole. The mechanism
consists of an incoming massless neutral scalar particle, with low energy and
large angular momentum, tunneling into the hole. We investigate the effect of
the large angular momentum of the incoming particle on the background geometry
and address recent claims that such a back-reaction would invalidate the
mechanism. We show that the large angular momentum of the incident particle
does not constitute an obvious impediment to the success of the overspinning
quantum mechanism, although the induced back-reaction turns out to be essential
to restoring the validity of the WCCC in the classical regime. These results
seem to endorse the view that the "cosmic censor" may be oblivious to processes
involving quantum effects.Comment: 5 pages, to appear as a Rapid Communication in Phys. Rev.
Weak decay of uniformly accelerated protons and related processes
We investigate the weak interaction emission of spin-1/2 fermions from
accelerated currents. As particular applications, we analyze the decay of
uniformly accelerated protons and neutrons, and the neutrino-antineutrino
emission from uniformly accelerated electrons. The possible relevance of our
results to astrophysics is also discussed.Comment: 16 pages (REVTEX), 6 figures, to appear in Physical Review
Semiclassical approach to the decay of protons in circular motion under the influence of gravitational fields
We investigate the possible decay of protons in geodesic circular motion
around neutral compact objects. Weak and strong decay rates and the associated
emitted powers are calculated using a semi-classical approach. Our results are
discussed with respect to distinct ones in the literature, which consider the
decay of accelerated protons in electromagnetic fields. A number of consistency
checks are presented along the paper.Comment: To appear in Physical Review
Diamonds's Temperature: Unruh effect for bounded trajectories and thermal time hypothesis
We study the Unruh effect for an observer with a finite lifetime, using the
thermal time hypothesis. The thermal time hypothesis maintains that: (i) time
is the physical quantity determined by the flow defined by a state over an
observable algebra, and (ii) when this flow is proportional to a geometric flow
in spacetime, temperature is the ratio between flow parameter and proper time.
An eternal accelerated Unruh observer has access to the local algebra
associated to a Rindler wedge. The flow defined by the Minkowski vacuum of a
field theory over this algebra is proportional to a flow in spacetime and the
associated temperature is the Unruh temperature. An observer with a finite
lifetime has access to the local observable algebra associated to a finite
spacetime region called a "diamond". The flow defined by the Minkowski vacuum
of a (four dimensional, conformally invariant) quantum field theory over this
algebra is also proportional to a flow in spacetime. The associated temperature
generalizes the Unruh temperature to finite lifetime observers.
Furthermore, this temperature does not vanish even in the limit in which the
acceleration is zero. The temperature associated to an inertial observer with
lifetime T, which we denote as "diamond's temperature", is 2hbar/(pi k_b
T).This temperature is related to the fact that a finite lifetime observer does
not have access to all the degrees of freedom of the quantum field theory.Comment: One reference correcte