BRST symmetry of SU(2) Yang-Mills theory in Cho--Faddeev--Niemi decomposition

We determine the nilpotent BRST and anti-BRST transformations for the Cho--Faddeev-Niemi variables for the SU(2) Yang-Mills theory based on the new interpretation given in the previous paper of the Cho--Faddeev-Niemi decomposition. This gives a firm ground for performing the BRST quantization of the Yang--Mills theory written in terms of the Cho--Faddeev-Niemi variables. We propose also a modified version of the new Maximal Abelian gauge which could play an important role in the reduction to the original Yang-Mills theory.Comment: 11 pages, no figure; Introduction improved, 3 references adde

Radion Dynamics and Phenomenology in the Linear Dilaton Model

We investigate the properties of the radion in the 5D linear dilaton model arising from Little String Theory. A Goldberger-Wise type mechanism is used to stabilise a large interbrane distance, with the dilaton now playing the role of the stabilising field. We consider the coupled fluctuations of the metric and dilaton fields and identify the physical scalar modes of the system. The wavefunctions and masses of the radion and Kaluza-Klein modes are calculated, giving a radion mass of order the curvature scale. As a result of the direct coupling between the dilaton and Standard Model fields, the radion couples to the SM Lagrangian, in addition to the trace of the energy-momentum tensor. The effect of these additional interaction terms on the radion decay modes is investigated, with a notable increase in the branching fraction to photons. We also consider the effects of a non-minimal Higgs coupling to gravity, which introduces a mixing between the Higgs and radion modes. Finally, we calculate the production cross section of the radion at the LHC and use the current Higgs searches to place constraints on the parameter space.Comment: 28 pages, 7 figures; v2: error in radion-gauge boson Feynman rules corrected, version published in JHE

The Sigma 13 (10-14) twin in alpha-Al2O3: A model for a general grain boundary

The atomistic structure and energetics of the Sigma 13 (10-14)[1-210] symmetrical tilt grain boundary in alpha-Al2O3 are studied by first-principles calculations based on the local-density-functional theory with a mixed-basis pseudopotential method. Three configurations, stable with respect to intergranular cleavage, are identified: one Al-terminated glide-mirror twin boundary, and two O-terminated twin boundaries, with glide-mirror and two-fold screw-rotation symmetries, respectively. Their relative energetics as a function of axial grain separation are described, and the local electronic structure and bonding are analysed. The Al-terminated variant is predicted to be the most stable one, confirming previous empirical calculations, but in contrast with high-resolution transmission electron microscopy observations on high-purity diffusion-bonded bicrystals, which resulted in an O-terminated structure. An explanation of this discrepancy is proposed, based on the different relative energetics of the internal interfaces with respect to the free surfaces

Inflation and Gauge Hierarchy in Randall-Sundrum Compactification

We obtain the general inflationary solutions for the slab of five-dimensional AdS spacetime where the fifth dimension is an orbifold $S^1/Z_2$ and two three-branes reside at its boundaries, of which the Randall-Sundrum model corresponds to the static limit. The investigation of the general solutions and their static limit reveals that the RS model recasts both the cosmological constant problem and the gauge hierarchy problem into the balancing problem of the bulk and the brane cosmological constants.Comment: 9 pages, revtex, minor changes and more references adde

Four-Dimensional Effective Supergravity and Soft Terms in M-Theory

We provide a simple macroscopic analysis of the four-dimensional effective supergravity of the Ho\v{r}ava-Witten M-theory which is expanded in powers of $\kappa^{2/3}/\rho V^{1/3}$ and $\kappa^{2/3}\rho/V^{2/3}$ where $\kappa^2$, $V$ and $\rho$ denote the eleven-dimensional gravitational coupling, the Calabi-Yau volume and the eleventh length respectively. Possible higher order terms in the K\"ahler potential are identified and matched with the heterotic string corrections. In the context of this M-theory expansion, we analyze the soft supersymmetry-breaking terms under the assumption that supersymmetry is spontaneously broken by the auxiliary components of the bulk moduli superfields. It is examined how the pattern of soft terms changes when one moves from the weakly coupled heterotic string limit to the M-theory limit.Comment: Latex, 23 pages, 3 figures. References are added and the discussion of the M-theory expansion parameters is enlarge

Electron affinity of Li: A state-selective measurement

We have investigated the threshold of photodetachment of Li^- leading to the formation of the residual Li atom in the $2p ^2P$ state. The excited residual atom was selectively photoionized via an intermediate Rydberg state and the resulting Li^+ ion was detected. A collinear laser-ion beam geometry enabled both high resolution and sensitivity to be attained. We have demonstrated the potential of this state selective photodetachment spectroscopic method by improving the accuracy of Li electron affinity measurements an order of magnitude. From a fit to the Wigner law in the threshold region, we obtained a Li electron affinity of 0.618 049(20) eV.Comment: 5 pages,6 figures,22 reference

DNA end resection by Dna2–Sgs1–RPA and its stimulation by Top3–Rmi1 and Mre11–Rad50–Xrs2

The repair of DNA double-strand breaks (DSBs) by homologous recombination requires processing of broken ends. For repair to start, the DSB must first be resected to generate a 3′-single-stranded DNA (ssDNA) overhang, which becomes a substrate for the DNA strand exchange protein, Rad51 (ref. 1). Genetic studies have implicated a multitude of proteins in the process, including helicases, nucleases and topoisomerases. Here we biochemically reconstitute elements of the resection process and reveal that it requires the nuclease Dna2, the RecQ-family helicase Sgs1 and the ssDNA-binding protein replication protein-A (RPA). We establish that Dna2, Sgs1 and RPA constitute a minimal protein complex capable of DNA resection in vitro. Sgs1 helicase unwinds the DNA to produce an intermediate that is digested by Dna2, and RPA stimulates DNA unwinding by Sgs1 in a species-specific manner. Interestingly, RPA is also required both to direct Dna2 nucleolytic activity to the 5′-terminated strand of the DNA break and to inhibit 3′ to 5′ degradation by Dna2, actions that generate and protect the 3′-ssDNA overhang, respectively. In addition to this core machinery, we establish that both the topoisomerase 3 (Top3) and Rmi1 complex and the Mre11–Rad50–Xrs2 complex (MRX) have important roles as stimulatory components. Stimulation of end resection by the Top3–Rmi1 heterodimer and the MRX proteins is by complex formation with Sgs1 (refs 5, 6), which unexpectedly stimulates DNA unwinding. We suggest that Top3–Rmi1 and MRX are important for recruitment of the Sgs1–Dna2 complex to DSBs. Our experiments provide a mechanistic framework for understanding the initial steps of recombinational DNA repair in eukaryotes

Antimony-doped graphene nanoplatelets

Heteroatom doping into the graphitic frameworks have been intensively studied for the development of metal-free electrocatalysts. However, the choice of heteroatoms is limited to non-metallic elements and heteroatom-doped graphitic materials do not satisfy commercial demands in terms of cost and stability. Here we realize doping semimetal antimony (Sb) at the edges of graphene nanoplatelets (GnPs) via a simple mechanochemical reaction between pristine graphite and solid Sb. The covalent bonding of the metalloid Sb with the graphitic carbon is visualized using atomic-resolution transmission electron microscopy. The Sb-doped GnPs display zero loss of electrocatalytic activity for oxygen reduction reaction even after 100,000 cycles. Density functional theory calculations indicate that the multiple oxidation states (Sb3+ and Sb5+) of Sb are responsible for the unusual electrochemical stability. Sb-doped GnPs may provide new insights and practical methods for designing stable carbon-based electrocatalystsclose0

Anomalous Normal Fluid Response in a Chiral Superconductor UTe₂

Chiral superconductors have been proposed as one pathway to realize Majorana normal fluid at its boundary. However, the long-sought 2D and 3D chiral superconductors with edge and surface Majorana normal fluid are yet to be conclusively found. Here, we report evidence for a chiral spin-triplet pairing state of UTe2 with surface normal fluid response. The microwave surface impedance of the UTe2 crystal was measured and converted to complex conductivity, which is sensitive to both normal and superfluid responses. The anomalous residual normal fluid conductivity supports the presence of a significant normal fluid response. The superfluid conductivity follows the temperature behavior predicted for an axial spin-triplet state, which is further narrowed down to a chiral spin-triplet state with evidence of broken time-reversal symmetry. Further analysis excludes trivial origins for the observed normal fluid response. Our findings suggest that UTe2 can be a new platform to study exotic topological excitations in higher dimension

ATIC and PAMELA Results on Cosmic e^\pm Excesses and Neutrino Masses

Recently the ATIC and PAMELA collaborations released their results which show the abundant e^\pm excess in cosmic rays well above the background, but not for the \bar{p}. Their data if interpreted as the dark matter particles' annihilation imply that the new physics with the dark matter is closely related to the lepton sector. In this paper we study the possible connection of the new physics responsible for the cosmic e^\pm excesses to the neutrino mass generation. We consider a class of models and do the detailed numerical calculations. We find that these models can natually account for the ATIC and PAMELA e^\pm and \bar{p} data and at the same time generate the small neutrino masses.Comment: 7 pages, 5 figures. Published version with minor corrections and more reference