Reply to the comment by D. Kreimer and E. Mielke

We respond to the comment by Kreimer et. al. about the torsional contribution to the chiral anomaly in curved spacetimes. We discuss their claims and refute its main conclusion.Comment: 9 pages, revte

Effectively four-dimensional spacetimes emerging from d=5 Einstein-Gauss-Bonnet Gravity

Einstein-Gauss-Bonnet gravity in five-dimensional spacetime provides an excellent example of a theory that, while including higher-order curvature corrections to General Relativity, still shares many of its features, such as second-order field equations for the metric. We focus on the largely unexplored case where the coupling constants of the theory are such that no constant-curvature solution is allowed, leaving open the question of what the vacuum state should then be. We find that even a slight deviation from the anti-de Sitter Chern-Simons theory, where the vacuum state is five-dimensional AdS spacetime, leads to a complete symmetry breakdown, with the fifth dimension either being compactified into a small circle or shrinking away exponentially with time. A complete family of solutions, including duality relations among them, is uncovered and shown to be unique within a certain class. This dynamical dimensional reduction scenario seems particularly attractive as a means for higher-dimensional theories to make contact with our four-dimensional world.Comment: 9 pages, 4 figures. v2: New section on geometrical significance of solutions. Final version for CQ

Geometry and stability of spinning branes in AdS gravity

The geometry of spinning codimension-two branes in AdS spacetime is analyzed in three and higher dimensions. The construction of non-extremal solutions is based on identifications in the covering of AdS space by isometries that have fixed points. The discussion focuses on the cases where the parameters of spinning states can be related to the velocity of a boosted static codimension-two brane. The resulting configuration describes a single spinning brane, or a set of intersecting branes, each one produced by an independent identification. The nature of the singularity is also examined, establishing that the AdS curvature acquires one in the form of a Dirac delta distribution. The stability of the branes is studied in the framework of Chern-Simons AdS supergravity. A class of branes, characterized by one free parameter, are shown to be stable when the BPS conditions are satisfied. In 3D, these stable branes are extremal, while in higher dimensions, the BPS branes are not the extremal ones.Comment: 40 pages, 6 figure

Birkhoff's Theorem for Three-Dimensional AdS Gravity

All three-dimensional matter-free spacetimes with negative cosmological constant, compatible with cyclic symmetry are identified. The only cyclic solutions are the 2+1 (BTZ) black hole with SO(2) x R isometry, and the self-dual Coussaert-Henneaux spacetimes, with isometry groups SO(2) x SO(2,1) or SO(2) x SO(2).Comment: 11 pages, RevTeX4; minor typos corrected, Ref. added, accepted for publication in Phys. Rev.

New Gauge Supergravity in Seven and Eleven Dimensions

Locally supersymmetric systems in odd dimensions whose Lagrangians are Chern-Simons forms for supersymmetric extensions of anti-de Sitter gravity are discussed. The construction is illustrated for D=7 and 11. In seven dimensions the theory is an N=2 supergravity whose fields are the vielbein ($e_{\mu}^{a}$), the spin connection ($\omega_{\mu}^{ab}$), two gravitini ($\psi_{\mu}^{i}$) and an $sp(2)$ gauge connection ($a_{\mu j}^{i}$). These fields form a connection for $osp(2|8)$. In eleven dimensions the theory is an N=1 supergravity containing, apart from $e_{\mu}^{a}$ and $\omega_{\mu}^{ab}$, one gravitino $\psi_{\mu}$, and a totally antisymmetric fifth rank Lorentz tensor one-form, $b_{\mu}^{abcde}$. These fields form a connection for $osp(32|1)$. The actions are by construction invariant under local supersymmetry and the algebra closes off shell without requiring auxiliary fields. The $N=2^{[D/2]}$-theory can be shown to have nonnegative energy around an AdS background, which is a classical solution that saturates the Bogomolnyi bound obtained from the superalgebra.Comment: 5pages, RevTeX, no figures, two columns, minor typos correcte

What is the Evidence for the Effectiveness of Scapulothoracic Strengthening Exercises in Individuals with Neck Pain: A Systematic Review

Neck pain is a highly prevalent issue, ranked as the fourth greatest issue worldwide in terms of overall disease burden, and consequently, places a substantial impact upon the healthcare system. Scapulothoracic exercises appear as a promising avenue for the treatment of neck pain amongst the various treatment options currently available. However, there is uncertainty surrounding the effectiveness and clinical application of this approach. Purpose: The aim of this review was to establish the evidence surrounding the clinical application and effectiveness of scapulothoracic strengthening exercises to reduce neck pain. Methods: A systematic search of four electronic databases, including Ovid Medline, Scopus, Ovid Embase and The Cochrane Library was conducted by two independent reviewers (EW, GW). Studies of adult participants who were receiving scapulothoracic strengthening exercises to reduce neck pain and improve functioning were included. Inclusion criteria were set to exclude participants with neck pain related to headaches or as a result of surgery, trauma, physiological abnormalities or neurological conditions. A total of 2,665 articles were evaluated for inclusion in this systematic review, with 39 included in a full-text screen and five included in the final review. Methodological quality was evaluated by three independent reviewers (AZ, HW, LO) using the PEDro critical appraisal tool and the National Health and Medical Research Council (NHMRC) hierarchy of evidence was used to determine included studies. Results: Five randomised controlled trials, encompassing a total of 329 participants, were included in this systematic review. Four of the studies investigated strength training for the non-painful scapulothoracic muscles, and one study included exercises targeting the painful upper trapezius muscle. Scapulothoracic intervention duration ranged from 20-90 minutes, with a varying frequency of 3-5 times per week. All five studies demonstrated some improvements in neck pain, with two included studies revealing short-term positive influences on activities of daily living and the neck disability index. One study showed significant improvements in neck range of motion and similarly, maximal voluntary contraction of cervical musculature improved in another study. Overall, analysis of the five included studies provided evidence that scapulothoracic strength exercises may be effective in alleviating neck pain. Conclusion: A limited number of studies have investigated the effect of scapulothoracic strengthening exercises as a primary modality in the treatment of neck pain. Scapulothoracic strengthening exercises could be considered in the treatment of neck pain, although the evidence is variable. Scapulothoracic strength training may have positive impacts across subjective and objective parameters including pain, and sequentially, activities of daily living, neck range of motion, and strength. However, the current literature base is limited by considerable diversity in intervention and outcome measures, and limited long-term follow up

Higher Dimensional Gravity, Propagating Torsion and AdS Gauge Invariance

The most general theory of gravity in d-dimensions which leads to second order field equations for the metric has [(d-1)/2] free parameters. It is shown that requiring the theory to have the maximum possible number of degrees of freedom, fixes these parameters in terms of the gravitational and the cosmological constants. In odd dimensions, the Lagrangian is a Chern-Simons form for the (A)dS or Poincare groups. In even dimensions, the action has a Born-Infeld-like form. Torsion may occur explicitly in the Lagrangian in the parity-odd sector and the torsional pieces respect local (A)dS symmetry for d=4k-1 only. These torsional Lagrangians are related to the Chern-Pontryagin characters for the (A)dS group. The additional coefficients in front of these new terms in the Lagrangian are shown to be quantized.Comment: 10 pages, two columns, no figures, title changed in journal, final version to appear in Class. Quant. Gra

Supersymmetry of gravitational ground states

A class of black objects which are solutions of pure gravity with negative cosmological constant are classified through the mapping between the Killing spinors of the ground state and those of the transverse section. It is shown that these geometries must have transverse sections of constant curvature for spacetime dimensions d below seven. For d > 6, the transverse sections can also be Euclidean Einstein manifolds. In even dimensions, spacetimes with transverse section of nonconstant curvature exist only in d = 8 and 10. This classification goes beyond standard supergravity and the eleven dimensional case is analyzed. It is shown that if the transverse section has negative scalar curvature, only extended objects can have a supersymmetric ground state. In that case, some solutions are explicitly found whose ground state resembles a wormhole.Comment: 16 pages, CECS style, minor correction