120600739
Possible duality aspects in e+−e− annihilation processes
Abstract Consequences of duality in e+−e−→ a hadron + anything, expressed by a finite mass sum rule, are obtained. A simple explicit solution of the sum rule is studied.
122228895
On the short distance behavior of string theories
Short distance behavior of string theories is investigated by the use of the discretized path-integral formulation. In particular, the minimum physical length and the generalized uncertainty relation are re-derived from a set of Ward–Takahashi identities. Several issues related to the form of the generalized uncertainty relation and to its implications are discussed. A consistent qualitative picture of short distance behavior of string theory seems to emerge from such a study.
119485873
A simple algorithm for QCD jets
Abstract A proposal is made, giving multiparticle (parton) spectra inside quark and gluon jets in terms of the tree diagrams of an effective field theory. The resulting “jet calculus” satisfies many consistency checks. A first sample of applications is given.
126281417
QCD Jet calculus
121970658
A Simple Algorithm for QCD Jets-An Introduction to Jet Calculus
A new, simple algorithm, recently proposed for QCD jets, is discussed. It allows to compute multiparton distributions inside QCD (q- or g-) jets, within the leading logarithmic approximation. Some of its applications are given.
123003167
Generation of mass hierarchies and gravitational instanton-induced supersymmetry breaking
Consequences of supersymmetry breaking by gravitational instantons are studied in the context of N = 1 supergravity models. In particular, models containing an additional term, proportional to the Euler characteristics density of the spacetime manifold, are shown to lead to a large hierarchy of masses, with the supersymmetry breaking mass scale much smaller than the Planck mass. Possible mechanisms of mass generation for gauge fermions, matter scalars and matter fermions are discussed. Models of this type can arise as a low-energy approximation to superstring models. Our analysis suggests the existence and importance of those nonperturbative effects in the underlying string theories that correspond to the Yang-Mills and gravitational instantons of low-energy effective field theories.
119204401
First-year Sloan Digital Sky Survey-II supernova results: consistency and constraints with other intermediate-redshift data sets
ABSTRACT We present an analysis of the luminosity distances of Type Ia Supernovae (SNe) from the Sloan Digital Sky Survey-II (SDSS-II) SN Survey in conjunction with other intermediate-redshift (z 97 per cent level from this single data set. We find good agreement between the SN and BAO distance measurements, both consistent with a Λ-dominated cold dark matter cosmology, as demonstrated through an analysis of the distance duality relationship between the luminosity (dL) and angular diameter (dA) distance measures. We then use these data to estimate w within this restricted redshift range (z < 0.4). Our most stringent result comes from the combination of all our intermediate-redshift data (SDSS-II SNe, BAO, ISW and redshift-space distortions), giving w = -0.81+0.16-0.18 (stat) +/- 0.15 (sys) and ΩM = 0.22+0.09-0.08 assuming a flat universe. This value of w and associated errors only change slightly if curvature is allowed to vary, consistent with constraints from the cosmic microwave background. We also consider more limited combinations of the geometrical (SN, BAO) and dynamical (ISW, redshift-space distortions) probes.
7368712
SDSS J1029+2623: A Gravitationally Lensed Quasar with an Image Separation of 22.5 Arcseconds
The authors report the discovery of a cluster-scale lensed quasar, SDSS J1029+2623, selected from the Sloan Digital Sky Survey. The lens system exhibits two lensed images of a quasar at z{sub s} = 2.197. The image separation of 22.5 makes it the largest separation lensed quasar discovered to date. The similarity of the optical spectra and the radio loudnesses of the two components support the lensing hypothesis. Images of the field show a cluster of galaxies at z{sub l} {approx} 0.55 that is responsible for the large image separation. The lensed images and the cluster light center are not collinear, which implies that the lensing cluster has a complex structure.
44348672
Type II-P supernovae from the SDSS-II supernova survey and the standardized candle method
We apply the Standardized Candle Method (SCM) for Type II Plateau supernovae (SNe II-P), which relates the velocity of the ejecta of a SN to its luminosity during the plateau, to 15 SNe II-P discovered over the three season run of the Sloan Digital Sky Survey-II Supernova Survey. The redshifts of these SNe—0.027 0.01) as all of the current literature on the SCM combined. We find that the SDSS SNe have a very small intrinsic I-band dispersion (0.22 mag), which can be attributed to selection effects. When the SCM is applied to the combined SDSS-plus-literature set of SNe II-P, the dispersion increases to 0.29 mag, larger than the scatter for either set of SNe separately. We show that the standardization cannot be further improved by eliminating SNe with positive plateau decline rates, as proposed in Poznanski et al. We thoroughly examine all potential systematic effects and conclude that for the SCM to be useful for cosmology, the methods currently used to determine the Fe II velocity at day 50 must be improved, and spectral templates able to encompass the intrinsic variations of Type II-P SNe will be needed.
119248886
Subaru Spectroscopy of SDSS-II Supernovae
The Sloan Digital Sky Survey II (SDSS-II) Supernova Survey discovered Type Ia supernovae (SNe Ia) in an almost unexplored intermediate redshift range of $0.05 < z < 0.4$ and provided densely sampled multi-color light curves for SN candidates. Followup spectroscopy of this survey was carried out with the Subaru telescope and spectra of 71 SN Ia candidates were obtained. One spectrum was observed per candidate except for a peculiar variable. This paper presents the method for processing these spectra. The observed wavelength ranges of our spectra are 4000 to 9000 {\AA} for Year 2005 and 3600 to 9000 {\AA} for Year 2006. Most SN Ia spectra have signal to noise ratios (S/N) between 4 and 10 per 2 {\AA} averaged over the entire wavelength region. We developed a new code to extract the SN spectral component from spectra contaminated by the host galaxy. Of 71 SN Ia candidates, 59 are identified as normal SNe Ia and 3 are peculiar SNe Ia. The range of spectral phases varies from -7 days to +30 days from maximum brightness. There are also 7 SNe II, 1 possible hypernova and 1 AGN.
118626595
A MISMATCH IN THE ULTRAVIOLET SPECTRA BETWEEN LOW-REDSHIFT AND INTERMEDIATE-REDSHIFT TYPE Ia SUPERNOVAE AS A POSSIBLE SYSTEMATIC UNCERTAINTY FOR SUPERNOVA COSMOLOGY
We present Keck high-quality rest-frame ultraviolet (UV) through optical spectra of 21 Type Ia supernovae (SNe?Ia) in the redshift range 0.11 ? z ? 0.37 and a mean redshift of 0.22 that were discovered during the Sloan Digital Sky Survey-II (SDSS-II) SN Survey. Using the broadband photometry of the SDSS survey, we are able to reconstruct the SN host-galaxy spectral energy distributions (SEDs), allowing for a correction for the host-galaxy contamination in the SN Ia spectra. Comparison of composite spectra constructed from a subsample of 17 high-quality spectra to those created from a low-redshift sample with otherwise similar properties shows that the Keck/SDSS SNe?Ia have, on average, extremely similar rest-frame optical spectra but show a UV flux excess. This observation is confirmed by comparing synthesized broadband colors of the individual spectra, showing a difference in mean colors at the 2.4?-4.4? level for various UV colors. We further see a slight difference in the UV spectral shape between SNe with low-mass and high-mass host galaxies. Additionally, we detect a relationship between the flux ratio at 2770 and 2900 ? and peak luminosity that differs from that observed at low redshift. We find that changing the UV SED of an SN Ia within the observed dispersion can change the inferred distance moduli by ~0.1?mag. This effect only occurs when the data probe the rest-frame UV. We suggest that this discrepancy could be due to differences in the host-galaxy population of the two SN samples or to small-sample statistics.