pi/K -> e nu branching ratios to O(e^2 p^4) in Chiral Perturbation Theory

We calculate the ratios R_{e/mu}^{(P)} = Gamma(P -> e nu)/Gamma (P -> mu nu) (P=pi,K) in Chiral Perturbation Theory to order e^2 p^4. We complement the one- and two-loop effective theory results with a matching calculation of the local counterterm, performed within the large-$N_C$ expansion. We find R_{e/mu}^{(\pi)} = (1.2352 \pm 0.0001)*10^{-4} and R_{e/mu}^{(K)} = (2.477 \pm 0.001)*10^{-5}, with uncertainty induced by the matching procedure and chiral power counting. Given the sensitivity of upcoming new measurements, our results provide a clean baseline to detect or constrain effects from weak-scale new physics in these rare decays. As a by-product, we also update the theoretical analysis of the individual pi/K -> \ell nu modes.Comment: 40 pages, 4 figures, 3 table

Study of γπ→ππ\gamma\pi \to \pi\pi below 1 GeV using Integral Equation Approach

The scattering of $\gamma \pi \to \pi \pi$ is studied using the axial anomaly, elastic unitarity, analyticity and crossing symmetry. Using the technique to derive the Roy's equation, an integral equation for the P-wave amplitude is obtained in terms of the strong P-wave pion pion phase shifts. Its solution is obtained numerically by an iteration procedure using the starting point as the solution of the integral equation of the Muskelshsvilli-Omnes type. It is, however, ambiguous and depends sensitively on the second derivative of the P-wave amplitude at $s=m_\pi^2$ which cannot directly be measured.Comment: 26 pages, 10 figure

Restoration of rotational invariance of bound states on the light front

We study bound states in a model with scalar nucleons interacting via an exchanged scalar meson using the Hamiltonian formalism on the light front. In this approach manifest rotational invariance is broken when the Fock space is truncated. By considering an effective Hamiltonian that takes into account two meson exchanges, we find that this breaking of rotational invariance is decreased from that which occurs when only one meson exchange is included. The best improvement occurs when the states are weakly bound.Comment: 20 pages, 6 figures, uses feynMF; changed typos, clarified use of angular momentu

The omega rho pi coupling in the VMD model revisited

We determine the value of the \omega -\rho- \pi mesons coupling (g_{\omega\rho\pi}), in the context of the vector meson dominance model, from radiative decays, the \omega \rightarrow 3\pi decay width and the e^+e^- \rightarrow 3\pi cross section. For the last two observables we consider the effect of either a heavier resonance (\rho'(1450)) or a contact term. A weighted average of the results from the set of observables yields g_{\omega\rho\pi} =14.7 \pm 0.1 GeV^{-1} in absence of those contributions, and g_{\omega\rho\pi} =11.9 \pm 0.2 GeV^{-1} or g_{\omega\rho\pi} =11.7 \pm 0.1 GeV^{-1} when including the \rho' or contact term respectively. The inclusion of these additional terms makes the estimates from the different observables to lay in a more reduced range. Improved measurements of these observables and the \rho'(1450) meson parameters are needed to give a definite answer on the pertinence of the inclusion of this last one in the considered processes.Comment: 14 pages, 5 figures. Extended analysis including SND and CMD2 data. References added. Matches published versio

Planet Hunters X: Searching for Nearby Neighbors of 75 Planet and Eclipsing Binary Candidates from the K2 Kepler Extended Mission

We present high-resolution observations of a sample of 75 K2 targets from Campaigns 1-3 using speckle interferometry on the Southern Astrophysical Research (SOAR) telescope and adaptive optics (AO) imaging at the Keck II telescope. The median SOAR $I$-band and Keck $K_s$-band detection limits at 1" were $\Delta m_{I}=4.4$~mag and $\Delta m_{K_s}=6.1$~mag, respectively. This sample includes 37 stars likely to host planets, 32 targets likely to be eclipsing binaries (EBs), and 6 other targets previously labeled as likely planetary false positives. We find nine likely physically bound companion stars within 3" of three candidate transiting exoplanet host stars and six likely EBs. Six of the nine detected companions are new discoveries; one of the six, EPIC 206061524, is associated with a planet candidate. Among the EB candidates, companions were only found near the shortest period ones ($P<3$ days), which is in line with previous results showing high multiplicity near short-period binary stars. This high-resolution data, including both the detected companions and the limits on potential unseen companions, will be useful in future planet vetting and stellar multiplicity rate studies for planets and binaries.Comment: Accepted in A

BG Ind: the nearest doubly eclipsing, compact hierarchical quadruple system

BG Ind is a well-studied, bright, nearby binary consisting of a pair of F stars in a 1.46-d orbit. We have discovered in the TESS light curve for TIC 229804573 (aka BG Ind), a second eclipsing binary in the system with a 0.53-d period. Our subsequent analyses of the recent TESS and archival ground-based photometric and radial velocity (RV) data reveal that the two binaries are gravitationally bound in a 721-d period, moderately eccentric orbit. We present the results of a joint spectro-photodynamical analysis of the eclipse timing variation curves of both binaries based on TESS and ground-based archival data, the TESS light curve, archival RV data, and the spectral energy distribution, coupled with the use of PARSEC stellar isochrones. We confirm prior studies of BG Ind that found that the brighter binary A consists of slightly evolved F-type stars with refined masses of 1.32 and 1.43 M-circle dot, and radii of 1.59 and 2.34 R-circle dot. The previously unknown binary B has two less massive stars of 0.69 and 0.64 M-circle dot and radii of 0.64 and 0.61 R-circle dot. Based on a number of different arguments that we discuss, we conclude that the three orbital planes are likely aligned to within 17 degrees

Radio Galaxy Zoo: discovery of a poor cluster through a giant wide-angle tail radio galaxy

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2016 J. K. Banfield, H. Andernach, A. D. Kapińska, L. Rudnick, M. J. Hardcastle, G. Cotter, S. Vaughan, T. W. Jones, I. Heywood, J. D. Wing, O. I. Wong, T. Matorny, I. A. Terentev, Á. R. López-Sánchez, R. P. Norris, N. Seymour, S. S. Shabala, and K. W. Willett. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. The version of record is available on line at doi: 10.1093/mnras/stw1067We have discovered a previously unreported poor cluster of galaxies (RGZ-CL J0823.2+0333) through an unusual giant wide-angle tail radio galaxy found in the Radio Galaxy Zoo project. We obtained a spectroscopic redshift of $z=0.0897$ for the E0-type host galaxy, 2MASX J08231289+0333016, leading to M$_r = -22.6$ and a $1.4\,$GHz radio luminosity density of $L_{\rm 1.4} = 5.5\times10^{24}$ W Hz$^{-1}$. These radio and optical luminosities are typical for wide-angle tailed radio galaxies near the borderline between Fanaroff-Riley (FR) classes I and II. The projected largest angular size of $\approx8\,$arcmin corresponds to $800\,$kpc and the full length of the source along the curved jets/trails is $1.1\,$Mpc in projection. X-ray data from the XMM-Newton archive yield an upper limit on the X-ray luminosity of the thermal emission surrounding RGZ J082312.9+033301,at $1.2-2.6\times10^{43}$ erg s$^{-1}$ for assumed intra-cluster medium temperatures of $1.0-5.0\,$keV. Our analysis of the environment surrounding RGZ J082312.9+033301 indicates that RGZ J082312.9+033301 lies within a poor cluster. The observed radio morphology suggests that (a) the host galaxy is moving at a significant velocity with respect to an ambient medium like that of at least a poor cluster, and that (b) the source may have had two ignition events of the active galactic nucleus with $10^7\,$yrs in between. This reinforces the idea that an association between RGZ J082312.9+033301, and the newly discovered poor cluster exists.Peer reviewe

Three-quark clusters at finite temperatures and densities

We present a relativistic three-body equation to study correlations in a medium of finite temperatures and densities. This equation is derived within a systematic Dyson equation approach and includes the dominant medium effects due to Pauli blocking and self energy corrections. Relativity is implemented utilizing the light front form. The equation is solved for a zero-range force for parameters close to the confinement-deconfinement transition of QCD. We present correlations between two- and three-particle binding energies and calculate the three-body Mott transition.Comment: 7 pages, 7 figure

A 2+1+1 quadruple star system containing the most eccentric, low-mass, short-period, eclipsing binary known

We present an analysis of a newly discovered 2+1+1 quadruple system with TESS containing an unresolved eclipsing binary (EB) as part of TIC 121088960 and a close neighbor TIC 121088959. The EB consists of two very low-mass M dwarfs in a highly-eccentric (e = 0.709) short-period (P = 3.04358 d) orbit. Given the large pixel size of TESS and the small separation (3${^{\prime\prime}_{.}}$9) between TIC 121088959 and TIC 121088960 we used light centroid analysis of the difference image between in-eclipse and out-of-eclipse data to show that the EB likely resides in TIC 121088960, but contributes only ∼10% of its light. Radial velocity data were acquired with iSHELL at NASA’s Infrared Facility and the Coudé spectrograph at the McDonald 2.7-m telescope. For both images, the measured RVs showed no variation over the 11-day observational baseline, and the RV difference between the two images was 8 ± 0.3 km s−1. The similar distances and proper motions of the two images indicate that TIC 121088959 and TIC 121088960 are a gravitationally bound pair. Gaia’s large RUWE and astrometric_excess_noise parameters for TIC 121088960, further indicate that this image is the likely host of the unresolved EB and is itself a triple star. We carried out an SED analysis and calculated stellar masses for the four stars, all of which are in the M dwarf regime: 0.19 M⊙ and 0.14 M⊙ for the EB stars and 0.43 M⊙ and 0.39 M⊙ for the brighter visible stars, respectively. Lastly, numerical simulations show that the orbital period of the inner triple is likely the range 1 to 50 years.Accepted manuscrip