99 research outputs found
Resummation Methods at Finite Temperature: The Tadpole Way
We examine several resummation methods for computing higher order corrections
to the finite temperature effective potential, in the context of a scalar
theory. We show by explicit calculation to four loops that dressing
the propagator, not the vertex, of the one-loop tadpole correctly counts
``daisy'' and ``super-daisy'' diagrams.Comment: 18 pages, LaTeX, CALT-68-1858, HUTP-93-A011, EFI-93-2
Corrections to the Electroweak Effective Action at Finite Temperature
We calculate contributions to the finite temperature effective action for the
electroweak phase transition (EWPT) at \O(g^4), {\it i.e.} at second order in
(g^2 T/\M) and all orders in (g^2 T^2/\M^2). This requires plasma-mass
corrections in the calculation of the effective potential, inclusion of the
``lollipop'' diagram, and an estimate of derivative corrections. We find the
EWPT remains too weakly first-order to drive baryogenesis. We calculate some
one loop kinetic energy corrections using both functional and diagrammatic
methods; these may be important for saddlepoint configurations such as the
bounce or sphaleron.Comment: LaTeX, 6 figures available by email, CALT-68-1795, HUTP-92-A027,
EFI-92-2
Thermal Activation Rates in the Chirally Asymmetric Gross-Neveu Model
We address the problem of how to incorporate quantum effects into the
calculation of finite-temperature decay rates for a metastable state of a
quantum field theory. To do this, we consider the Gross-Neveu model with an
explicit chiral symmetry breaking term, which allows for a metastable state.
This theory can be shown to have a "critical bubble" which is a solution to the
*exact* equations of motions (i.e. to all orders in perturbation theory,
including all higher derivative, quantum and thermal corrections). This
configuration mediates the thermal activation of the metastable vacuum to the
true ground state, with a decay rate , where
is the free energy of the critical bubble. We then compare this exact
calculation to various approximations that have been used in previous work. We
find that these approximations all *overestimate* the activation rate.
Furthermore, we study the effect of finite baryon number upon the bubble
profile and the activation barriers. We find that beyond a critical baryon
number the activation barriers disappear altogether.Comment: 20 pages, LaTeX, 9 figures using epsf.tex. Now auto-generates P
The Exact Critical Bubble Free Energy and the Effectiveness of Effective Potential Approximations
To calculate the temperature at which a first-order cosmological phase
transition occurs, one must calculate , the free energy of a critical
bubble configuration. is often approximated by the classical energy
plus an integral over the bubble of the effective potential; one must choose a
method for calculating the effective potential when . We test different
effective potential approximations at one loop. The agreement is best if one
pulls a factor of into the decay rate prefactor [where ], and takes the real part of the effective potential in the region
. We perform a similar analysis on the 1-dimensional kink.Comment: 11 pages plus 3 figures in jyTeX; CALT-68-188
A systematic review of the safety of lisdexamfetamine dimesylate
BACKGROUND: Here we review the safety and tolerability profile of lisdexamfetamine dimesylate (LDX), the first long-acting prodrug stimulant for the treatment of attention-deficit/hyperactivity disorder (ADHD). METHODS: A PubMed search was conducted for English-language articles published up to 16 September 2013 using the following search terms: (lisdexamfetamine OR lisdexamphetamine OR SPD489 OR Vyvanse OR Venvanse OR NRP104 NOT review [publication type]). RESULTS: In short-term, parallel-group, placebo-controlled, phase III trials, treatment-emergent adverse events (TEAEs) in children, adolescents, and adults receiving LDX were typical for those reported for stimulants in general. Decreased appetite was reported by 25-39 % of patients and insomnia by 11-19 %. The most frequently reported TEAEs in long-term studies were similar to those reported in the short-term trials. Most TEAEs were mild or moderate in severity. Literature relating to four specific safety concerns associated with stimulant medications was evaluated in detail in patients receiving LDX. Gains in weight, height, and body mass index were smaller in children and adolescents receiving LDX than in placebo controls or untreated norms. Insomnia was a frequently reported TEAE in patients with ADHD of all ages receiving LDX, although the available data indicated no overall worsening of sleep quality in adults. Post-marketing survey data suggest that the rate of non-medical use of LDX was lower than that for short-acting stimulants and lower than or equivalent to long-acting stimulant formulations. Small mean increases were seen in blood pressure and pulse rate in patients receiving LDX. CONCLUSIONS: The safety and tolerability profile of LDX in individuals with ADHD is similar to that of other stimulants
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