1,272 research outputs found
Gaps between Jets in the High Energy Limit
We use perturbative QCD to calculate the parton level cross section for the
production of two jets that are far apart in rapidity, subject to a limitation
on the total transverse momentum Q0 in the interjet region. We specifically
address the question of how to combine the approach which sums all leading
logarithms in Q/Q0 (where Q is the jet transverse momentum) with the BFKL
approach, in which leading logarithms of the scattering energy are summed. This
paper constitutes progress towards the simultaneous summation of all important
logarithms. Using an "all orders" matching, we are able to obtain results for
the cross section which correctly reproduce the two approaches in the
appropriate limits.Comment: 29 pages, 9 figures, minor corrections to text and improved figure
Synthetic Mudscapes: Human Interventions in Deltaic Land Building
In order to defend infrastructure, economy, and settlement in Southeast Louisiana, we must construct new land to
mitigate increasing risk. Links between urban environments and economic drivers have constrained the dynamic delta
landscape for generations, now threatening to undermine the ecological fitness of the entire region. Static methods of
measuring, controlling, and valuing land fail in an environment that is constantly in flux; change and indeterminacy are
denied by traditional inhabitation.
Multiple land building practices reintroduce deltaic fluctuation and strategic deposition of fertile material to form the
foundations of a multi-layered defence strategy. Manufactured marshlands reduce exposure to storm surge further
inland. Virtual monitoring and communication networks inform design decisions and land use becomes determined
by its ecological health. Mudscapes at the threshold of land and water place new value on former wastelands. The
social, economic, and ecological evolution of the region are defended by an expanded web of growing land
Counting and computing regions of -decomposition: algebro-geometric approach
New methods for -decomposition analysis are presented. They are based on
topology of real algebraic varieties and computational real algebraic geometry.
The estimate of number of root invariant regions for polynomial parametric
families of polynomial and matrices is given. For the case of two parametric
family more sharp estimate is proven. Theoretic results are supported by
various numerical simulations that show higher precision of presented methods
with respect to traditional ones. The presented methods are inherently global
and could be applied for studying -decomposition for the space of parameters
as a whole instead of some prescribed regions. For symbolic computations the
Maple v.14 software and its package RegularChains are used.Comment: 16 pages, 8 figure
Vector Meson Photoproduction from the BFKL Equation II: Phenomenology
Diffractive vector meson photoproduction accompanied by proton dissociation
is studied for large momentum transfer. The process is described by the
non-forward BFKL equation which we use to compare to data collected at the HERA
collider.Comment: 39 pages, 29 figure
Thermodynamics of volume collapse transitions in cerium and related compounds
We present a non-linear elastic model of a coherent transition with
discontinuous volume change in an isotropic solid. The model reproduces the
anomalous thermodynamics typical of coherent equilibrium including intrinsic
hysteresis (for a pressure driven experiment) and a negative bulk modulus. The
novelty of the model is that the statistical mechanics solution can be easily
worked out. We find that coherency leads to an infinite-range density--density
interaction, which drives classical critical behavior. The pressure width of
the hysteresis loop shrinks with increasing temperature, ending at a critical
point at a temperature related to the shear modulus. The bulk modulus softens
with a 1/2 exponent at the transition even far from the critical point. Many
well known features of the phase diagram of Ce and related systems are
explained by the model.Comment: Acta Materialia, in pres
Soft gluons in Higgs plus two jet production
We investigate the effects of an all order QCD resummation of soft gluon
emissions for Higgs boson production in association with two hard jets. We
consider both the gluon-gluon fusion and weak boson fusion processes and show
how to resum a large part of the leading logarithms in the jet veto scale. Our
resummation improves on previous analyses which also aim to include the effects
of multiple soft gluon radiation. In addition we calculate the interference
between weak boson fusion and gluon-gluon fusion and find that it is small.Comment: 15 pages and 5 figure
Non-cubic layered structure of Ba(1-x)K(x)BiO3 superconductor
Bismuthate superconductor Ba(1-x)K(x)BiO3 (x=0.27-0.49, Tc=25-32K) grown by
an electrolysis technique was studied by electron diffraction and
high-resolution electron microscopy. The crystalline structure thereof has been
found to be non-cubic, of the layered nature, and non-centrosymmetric, with the
lattice parameters a ~ ap, c ~ 2ap (ap is a simple cubic perovskite cell
parameter) containing an ordered arrangement of barium and potassium. The
evidence for the layered nature of the bismuthate superconductor removes the
principal crystallographic contradiction between bismuthate and cuprate high-Tc
superconductors.Comment: 4 pages, 3 figures, to be published in Physical Review B as a Rapid
Communicatio
Non-geometric flux vacua, S-duality and algebraic geometry
The four dimensional gauged supergravities descending from non-geometric
string compactifications involve a wide class of flux objects which are needed
to make the theory invariant under duality transformations at the effective
level. Additionally, complex algebraic conditions involving these fluxes arise
from Bianchi identities and tadpole cancellations in the effective theory. In
this work we study a simple T and S-duality invariant gauged supergravity, that
of a type IIB string compactified on a orientifold with
O3/O7-planes. We build upon the results of recent works and develop a
systematic method for solving all the flux constraints based on the algebra
structure underlying the fluxes. Starting with the T-duality invariant
supergravity, we find that the fluxes needed to restore S-duality can be simply
implemented as linear deformations of the gauge subalgebra by an element of its
second cohomology class. Algebraic geometry techniques are extensively used to
solve these constraints and supersymmetric vacua, centering our attention on
Minkowski solutions, become systematically computable and are also provided to
clarify the methods.Comment: 47 pages, 10 tables, typos corrected, Accepted for Publication in
Journal of High Energy Physic
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