Charged Black Holes in Two-Dimensional String Theory

We discuss two dimensional string theories containing gauge fields introduced either via coupling to open strings, in which case we get a Born-Infeld type action, or via heterotic compactification. The solutions to the modified background field equations are charged black holes which exhibit interesting space-time geometries. We also compute their masses and charges.Comment: 39 page

Hydrogen-atom Attack on Phenol and Toluene is \u3cem\u3eortho\u3c/em\u3e-directed

The reaction of H + phenol and H/D + toluene has been studied in a supersonic expansion after electric discharge. The (1 + 1′) resonance-enhanced multiphoton ionization (REMPI) spectra of the reaction products, at m/z = parent + 1, or parent + 2 amu, were measured by scanning the first (resonance) laser. The resulting spectra are highly structured. Ionization energies were measured by scanning the second (ionization) laser, while the first laser was tuned to a specific transition. Theoretical calculations, benchmarked to the well-studied H + benzene → cyclohexadienyl radical reaction, were performed. The spectrum arising from the reaction of H + phenol is attributed solely to the ortho-hydroxy-cyclohexadienyl radical, which was found in two conformers (syn and anti). Similarly, the reaction of H/D + toluene formed solely the ortho isomer. The preference for the ortho isomer at 100–200 K in the molecular beam is attributed to kinetic, not thermodynamic effects, caused by an entrance channel barrier that is ∼5 kJ mol−1 lower for ortho than for other isomers. Based on these results, we predict that the reaction of H + phenol and H + toluene should still favour the ortho isomer under elevated temperature conditions in the early stages of combustion (200–400 °C)

Heart failure with preserved ejection fraction (HFpEF) pathophysiology study (IDENTIFY-HF): does increased arterial stiffness associate with HFpEF, in addition to ageing and vascular effects of comorbidities? Rationale and design

Aims: There has been a paradigm shift proposing that comorbidities are a major contributor towards the heart failure with preserved ejection fraction (HFpEF) syndrome. Furthermore, HFpEF patients have abnormal macrovascular and microvascular function, which may significantly contribute towards altered ventricular-vascular coupling in these patients. The IDENTIFY-HF study will investigate whether gradually increased arterial stiffness (in addition to ageing) as a result of increasing common comorbidities, such as hypertension and diabetes, is associated with HFpEF. Methods and analysis: In our observational study, arterial compliance and microvascular function will be assessed in five groups (Groups A to E) of age, sex and body mass index matched subjects (age ≥70 years in all groups): Group A; normal healthy volunteers without major comorbidities such as hypertension and diabetes mellitus (control). Group B; patients with hypertension without diabetes mellitus or heart failure (HF). Group C; patients with hypertension and diabetes mellitus without HF. Group D; patients with HFpEF. Group E; patients with heart failure and reduced ejection fraction (parallel group). Vascular function and arterial compliance will be assessed using pulse wave velocity, as the primary outcome measure. Further outcome measures include cutaneous laser Doppler flowmetry as a measure of endothelial function, transthoracic echocardiography and exercise tolerance measures. Biomarkers include NT-proBNP, high-sensitivity troponin T, as well as serum galectin-3 as a marker of fibrosis. Ethics and dissemination: The study was approved by the regional research ethics committee (REC), West Midland and Black Country 17/WM/0039, UK, and permission to conduct the study in the hospital was also obtained from the RDI, UHCW NHS Trust. The results will be published in peer-reviewed journals and presented in local, national and international medical society meetings. Trial registration number: NCT0318683

Fluctuating solutions for the evolution of domain walls

A class of oscillating Lorentz covariant configurations for the evolution of the domain walls in diverse dimensions are analytically obtained. It is shown that the oscillating solutions in the case of domain walls are responsible for structures which are larger than the usual kink-like configurations and, in the Lorentz covariant evolution case, lead to long-standing configurations.Comment: 14 pages, 7 figure

Oscillons: Resonant Configurations During Bubble Collapse

Oscillons are localized, non-singular, time-dependent, spherically-symmetric solutions of nonlinear scalar field theories which, although unstable, are extremely long-lived. We show that they naturally appear during the collapse of subcritical bubbles in models with symmetric and asymmetric double-well potentials. By a combination of analytical and numerical work we explain several of their properties, including the conditions for their existence, their longevity, and their final demise. We discuss several contexts in which we expect oscillons to be relevant. In particular, their nucleation during cosmological phase transitions may have wide-ranging consequences.Comment: 31 pages Revtex, 20 uufiles-encoded figures. Section "Possible Applications of Oscillons" slightly expande

De Sitter and Schwarzschild-De Sitter According to Schwarzschild and De Sitter

When de Sitter first introduced his celebrated spacetime, he claimed, following Schwarzschild, that its spatial sections have the topology of the real projective space RP^3 (that is, the topology of the group manifold SO(3)) rather than, as is almost universally assumed today, that of the sphere S^3. (In modern language, Schwarzschild was disturbed by the non-local correlations enforced by S^3 geometry.) Thus, what we today call "de Sitter space" would not have been accepted as such by de Sitter. There is no real basis within classical cosmology for preferring S^3 to RP^3, but the general feeling appears to be that the distinction is in any case of little importance. We wish to argue that, in the light of current concerns about the nature of de Sitter space, this is a mistake. In particular, we argue that the difference between "dS(S^3)" and "dS(RP^3)" may be very important in attacking the problem of understanding horizon entropies. In the approach to de Sitter entropy via Schwarzschild-de Sitter spacetime, we find that the apparently trivial difference between RP^3 and S^3 actually leads to very different perspectives on this major question of quantum cosmology.Comment: 26 pages, 8 figures, typos fixed, references added, equation numbers finally fixed, JHEP versio

A Step Beyond the Bounce: Bubble Dynamics in Quantum Phase Transitions

We study the dynamical evolution of a phase interface or bubble in the context of a \lambda \phi^4 + g \phi^6 scalar quantum field theory. We use a self-consistent mean-field approximation derived from a 2PI effective action to construct an initial value problem for the expectation value of the quantum field and two-point function. We solve the equations of motion numerically in (1+1)-dimensions and compare the results to the purely classical evolution. We find that the quantum fluctuations dress the classical profile, affecting both the early time expansion of the bubble and the behavior upon collision with a neighboring interface.Comment: 12 pages, multiple figure

Quantum Fields and Extended Objects in Space-Times with Constant Curvature Spatial Section

The heat-kernel expansion and $\zeta$-regularization techniques for quantum field theory and extended objects on curved space-times are reviewed. In particular, ultrastatic space-times with spatial section consisting in manifold with constant curvature are discussed in detail. Several mathematical results, relevant to physical applications are presented, including exact solutions of the heat-kernel equation, a simple exposition of hyperbolic geometry and an elementary derivation of the Selberg trace formula. With regards to the physical applications, the vacuum energy for scalar fields, the one-loop renormalization of a self-interacting scalar field theory on a hyperbolic space-time, with a discussion on the topological symmetry breaking, the finite temperature effects and the Bose-Einstein condensation, are considered. Some attempts to generalize the results to extended objects are also presented, including some remarks on path integral quantization, asymptotic properties of extended objects and a novel representation for the one-loop (super)string free energy.Comment: Latex file, 122 page