11936862
Bootes II: Not a Dwarf Galaxy but Possibly Shed by One
We present moderately deep V I C photometry of Boötes II, obtained using the SOAR Telescope. While identified initially as an old, metal-poor, dwarf galaxy, Boötes II appears to be a moderately metal-rich globular cluster with [Fe/H] ≈ −0.7. The slope of the red giant branch suggests that [α/Fe] ≈ 0.0, and the turn-off indicates an age of 7 to 9 Gyrs, considerably younger than most globular clusters, but similar to Palomar 12. Like that object, Boötes II lies in the direction of the Sagittarius dwarf galaxy tidal stream, and, with a distance of almost 50 kpc, is probably associated with the more distant portion of the stream, as defined by Belokurov et al. (2006a).
2150926
A Chemical Abundance Study of three RHB and two RGB stars in NGC6637 (M69)
We present a detailed chemical abundance study of three red horizontal branch and two red giant branch stars in the metal-rich globular cluster NGC 6637 (M69). The value of [Fe/H] derived from LTE calculations is $-$0.77 $\pm$ 0.02 dex. We also discuss the anticorrelation between oxygen and sodium abundances in the program stars and compare the [Si/Ti] ratio of NGC 6637 with those of other globular clusters.
118885035
INFRARED PHOTOMETRY OF NGC 6791
We present deep JHK photometry of the old and metal-rich open cluster NGC 6791. The photometry reaches below the main-sequence turnoff to K ≈ 16.5 mag. We combine our photometry with that from Stetson et al. to provide color-magnitude diagrams showing K versus J - K, K versus V - K, and V versus V - K. We study the slope of the red giant branch in the infrared but find that it is not a useful metallicity indicator for the cluster, nor any metal-rich cluster that lacks a well-populated red giant branch, because it is not linear, as has often been assumed, in K versus J - K. The mean color of the red horizontal-branch/red clump stars provide an estimate of the cluster reddening, E(B - V) = 0.14 ± 0.04 mag for [Fe/H] = +0.4 ± 0.1. The mean magnitudes of these stars also provide a good distance estimate, (m - M)0 = 13.07 ± 0.04. Finally, we find that the isochrones of Yi et al. provide optimal fits in V versus B - V and V - K and K versus J - K and V - K for such values if [Fe/H] lies between +0.3 and +0.5 (with a slight preference for +0.5) and ages between 9 Gyr ([Fe/H] = +0.3) and 7.5 Gyr ([Fe/H] = +0.5).
119279392
THE RR LYRAE VARIABLES AND HORIZONTAL BRANCH OF NGC 6656 (M22)
The first calibrated broadband UBVI time-series photometry is presented for the RR Lyrae variable stars in NGC 6656 (M22), with observations spanning a range of 22 years. We have also redetermined the variability types and periods for the RR Lyrae stars identified previously by photographic observations, revising the number of fundamental-mode RR Lyrae variables (RR0) to 10 and the number of first-overtone variables (RR1) to 16. The mean periods of the RR0 and RR1 variables are (P) {sub RR0} = 0.66 ± 0.02 days and (P) {sub RR1} = 0.33 ± 0.01 days, respectively, supporting an Oosterhoff II classification for the cluster. The number ratio of RR1-type to all RR-type variables is N {sub 1}/N{sub RR} = 0.61, also consistent with an Oosterhoff II designation. Both the RR Lyrae stars' minimum light colors and the blue edge of the RR Lyrae instability strip suggest E( B – – V) = 0.36 ± 0.02 mag toward M22. Regarding the HB morphology of M22, we find (B-R)/(B+V+R) = +0.97 ± 0.1 and at least one ''gap'' located in an unusual part of the blue HB, in the middle of the so-called hot HB stars.
205218920
Enrichment by supernovae in globular clusters with multiple populations
The most massive globular cluster in the Milky Way, ω Centauri, is thought to be the remaining core of a disrupted dwarf galaxy, as expected within the model of hierarchical merging. It contains several stellar populations having different heavy elemental abundances supplied by supernovae—a process known as metal enrichment. Although M 22 appears to be similar to ω Cen, other peculiar globular clusters do not. Therefore ω Cen and M 22 are viewed as exceptional, and the presence of chemical inhomogeneities in other clusters is seen as ‘pollution’ from the intermediate-mass asymptotic-giant-branch stars expected in normal globular clusters. Here we report Ca abundances for seven globular clusters and compare them to ω Cen. Calcium and other heavy elements can only be supplied through numerous supernovae explosions of massive stars in these stellar systems, but the gravitational potentials of the present-day clusters cannot preserve most of the ejecta from such explosions. We conclude that these globular clusters, like ω Cen, are most probably the relics of more massive primeval dwarf galaxies that merged and disrupted to form the proto-Galaxy.
35634571
Expression of Interest and RD Proposal for the Study of Nucleon Decay and Neutrino Physics Using a Large Underground Water Cherenkov Detector: UNO
122930718
Measurements of the meson-photon transition form factors of light pseudoscalar mesons at large momentum transfer
Using the CLEO II detector, we have measured the differential cross sections for exclusive two-photon production of light pseudoscalar mesons {pi}{sup 0}, {eta}, and {eta}{prime}. From our measurements we have obtained the form factors associated with the electromagnetic transitions {gamma}*{gamma} {yields} meson. We have measured these form factors in the momentum transfer ranges from 1.5 to 9, 20, and 30 GeV2 for {pi}{sup 0}, {eta}, and {eta}{prime}, respectively, and have made comparisons to various theoretical predictions.
119280259
Physics from information
Department of energy resources development, Jungwon University,5 dongburi, Goesan-eup, Goesan-gun Chungbuk Korea 367-805(Dated: November 9, 2010)This is an ongoing review on my conjecture that information processing at causal horizons isthe key ingredient of all physics. Assuming that information is fundamental and the informationpropagates with ﬁnite velocity, one can ﬁnd that main physical laws such as Newton’s second law andEinstein equation simply describe the energy-information relation (dE=TdS) for matter or spacetime crossing a causal horizon with temperature T for observers. Quantum mechanics arises fromignorance of the observers about matter crossing the horizon, which explains why superluminalcommunication is impossible even with quantum entanglement. This approach also explains theorigin of Jacobson’s thermodynamic formalism of Einstein gravity and Verlinde’s entropic gravity.When applied to a cosmic causal horizon, the conjecture reproduces the observed dark energy anddemands the zero cosmological constant.
118494859
Gravity from quantum information
We suggest that the Einstein equation can be derived from Landauer’s principle applied to an information erasing process at a local Rindler horizon and Jacobson’s idea linking the Einstein equation with thermodynamics. When matter crosses the horizon, information on the matter disappears, and the horizon entanglement entropy increases to compensate for the entropy reduction. The Einstein equation describes an information-energy relation during this process, which implies that entropic gravity is related to the quantum entanglement of the vacuum and has a quantuminformation theoretic origin.
12364980
First limit on WIMP cross section with low background CsI(Tℓ) crystal detector
Abstract The Korea Invisible Mass Search (KIMS) Collaboration has been carrying out WIMP search experiment with CsI ( T l ) crystal detectors at the YangYang Underground Laboratory. A successful reduction of the internal background of the crystal was done and a good pulse shape discrimination was achieved. We report the first result on WIMP search obtained with 237 kg days data using one full-size CsI ( T l ) crystal of 6.6 kg mass.
209521249
Search for long-lived, heavy particles in final states with a muon and multi-track displaced vertex in proton-proton collisions at √s=7 TeV with the ATLAS detector
Many extensions of the Standard Model posit the existence of heavy particles with long lifetimes. In this Letter, results are presented of a search for events containing one or more such particles, which decay at a significant distance from their production point, using a final state containing charged hadrons and an associated muon. This analysis uses a data sample of proton-proton collisions at root s = 7 TeV corresponding to an integrated luminosity of 4.4 fb(-1) collected in 2011 by the ATLAS detector operating at the Large Hadron Collider. Results are interpreted in the context of R-parity violating supersymmetric scenarios. No events in the signal region are observed and limits are set on the production cross section for pair production of supersymmetric particles, multiplied by the square of the branching fraction for a neutralino to decay to charged hadrons and a muon, based on the scenario where both of the produced supersymmetric particles give rise to neutralinos that decay in this way. However, since the search strategy is based on triggering on and reconstructing the decay products of individual long-lived particles, irrespective of the rest of the event, these limits can easily be reinterpreted in scenarios with different numbers of long-lived particles per event. The limits are presented as a function of neutralino lifetime, and for a range of squark and neutralino masses.