5,058 research outputs found
Energy Correlation Functions for Jet Substructure
We show how generalized energy correlation functions can be used as a
powerful probe of jet substructure. These correlation functions are based on
the energies and pair-wise angles of particles within a jet, with (N+1)-point
correlators sensitive to N-prong substructure. Unlike many previous jet
substructure methods, these correlation functions do not require the explicit
identification of subjet regions. In addition, the correlation functions are
better probes of certain soft and collinear features that are masked by other
methods. We present three Monte Carlo case studies to illustrate the utility of
these observables: 2-point correlators for quark/gluon discrimination, 3-point
correlators for boosted W/Z/Higgs boson identification, and 4-point correlators
for boosted top quark identification. For quark/gluon discrimination, the
2-point correlator is particularly powerful, as can be understood via a
next-to-leading logarithmic calculation. For boosted 2-prong resonances the
benefit depends on the mass of the resonance.Comment: 45 pages, 28 figures, update to JHEP version, some minor typos fixed,
added discussion at end of section
Physical and magnetic properties of Ba(FeRu)As single crystals
Single crystals of Ba(FeRu)As, , have been grown
and characterized by structural, magnetic and transport measurements. These
measurements show that the structural/magnetic phase transition found in pure
BaFeAs at 134 K is suppressed monotonically by Ru doping, but, unlike
doping with TM=Co, Ni, Cu, Rh or Pd, the coupled transition seen in the parent
compound does not detectably split into two separate ones. Superconductivity is
stabilized at low temperatures for and continues through the highest
doping levels we report. The superconducting region is dome like, with maximum
T ( K) found around . A phase diagram of temperature
versus doping, based on electrical transport and magnetization measurements,
has been constructed and compared to those of the
Ba(FeTM)As (TM=Co, Ni, Rh, Pd) series as well as to the
temperature-pressure phase diagram for pure BaFeAs. Suppression of the
structural/magnetic phase transition as well as the appearance of
superconductivity is much more gradual in Ru doping, as compared to Co, Ni, Rh
and Pd doping, and appears to have more in common with BaFeAs tuned
with pressure; by plotting and as a function of changes in unit
cell dimensions, we find that changed in the ratio, rather than changes
in , or V, unify the and phase diagrams for BaFeAs
and Ba(FeRu)As respectively.Comment: 16 pages, 10 figure
Effect of electron irradiation on superconductivity in single crystals of Ba(FeRu)As (0.24)
A single crystal of isovalently substituted Ba(FeRu)As
() was sequentially irradiated with 2.5 MeV electrons up to a maximum
dose of electrons/cm^2. The electrical resistivity was
measured \textit{in - situ} at 22 K during the irradiation and \textit{ex -
situ} as a function of temperature between subsequent irradiation runs. Upon
irradiation, the superconducting transition temperature, , decreases and
the residual resistivity, , increases. We find that electron
irradiation leads to the fastest suppression of compared to other types
of artificially introduced disorder, probably due to the strong short-range
potential of the point-like irradiation defects. A more detailed analysis
within a multiband scenario with variable scattering potential strength shows
that the observed vs. is fully compatible with pairing,
in contrast to earlier claims that this model leads to a too rapid a
suppression of with scattering
Generalized Arcsine Law and Stable Law in an Infinite Measure Dynamical System
Limit theorems for the time average of some observation functions in an
infinite measure dynamical system are studied. It is known that intermittent
phenomena, such as the Rayleigh-Benard convection and Belousov-Zhabotinsky
reaction, are described by infinite measure dynamical systems.We show that the
time average of the observation function which is not the function,
whose average with respect to the invariant measure is finite, converges to
the generalized arcsine distribution. This result leads to the novel view that
the correlation function is intrinsically random and does not decay. Moreover,
it is also numerically shown that the time average of the observation function
converges to the stable distribution when the observation function has the
infinite mean.Comment: 8 pages, 8 figure
Reference Distorted Prices
I show that when consumers (mis)perceive prices relative to reference prices,
budgets turn out to be soft, prices tend to be lower and the average quality of
goods sold decreases. These observations provide explanations for decentralized
purchase decisions, for people being happy with a purchase even when they have
paid their evaluation, and for why trade might affect high quality local firms
'unfairly'
Dark Matter through the Axion Portal
Motivated by the galactic positron excess seen by PAMELA and ATIC/PPB-BETS,
we propose that dark matter is a TeV-scale particle that annihilates into a
pseudoscalar "axion." The positron excess and the absence of an anti-proton or
gamma ray excess constrain the axion mass and branching ratios. In the simplest
realization, the axion is associated with a Peccei-Quinn symmetry, in which
case it has a mass around 360-800 MeV and decays into muons. We present a
simple and predictive supersymmetric model implementing this scenario, where
both the Higgsino and dark matter obtain masses from the same source of
TeV-scale spontaneous symmetry breaking.Comment: 5 pages; reference adde
On the informational content of wage offers
This article investigates signaling and screening roles of wage offers in a single-play matching model with two-sided unobservable characteristics. It generates the following predictions as matching equilibrium outcomes: (i) âgoodâ jobs offer premia if âhigh-qualityâ worker population is large; (ii) âbadâ jobs pay compensating differentials if the proportion of âgoodâ jobs to âlow-qualityâ workers is large; (iii) all firms may offer a pooling wage in markets dominated by âhigh-qualityâ workers and firms; or (iv) Greshamâs Law prevails: âgoodâ types withdraw if âbadâ types dominate the population. The screening/signaling motive thus has the potential of explaining a variety of wage patterns
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