1,445 research outputs found
Electroweak non-resonant corrections to top pair production close to threshold
The production of W+ W- b bbar from e+ e- collisions at energies close to the
t tbar threshold is dominated by the resonant process with a nearly on-shell t
tbar intermediate state. The W b pairs in the final state can also be reached
through the decay of off-shell tops or through background processes containing
no or only single top quarks. This non-resonant production starts to contribute
at NLO to the W+ W- b bbar total cross section in the non-relativistic
power-counting v ~ alpha_s ~ sqrt(alpha_EW). The NLO non-resonant corrections
presented in this talk represent the non-trivial NLO electroweak corrections to
the e+ e- -> W+ W- b bbar cross section in the top anti-top resonance region.
In contrast to the QCD corrections which have been calculated (almost) up to
NNNLO, the parametrically larger NLO electroweak contributions have not been
completely known so far, but are mandatory for the required accuracy at a
future linear collider. We consider the total cross section of the e+ e- -> W+
W- b bbar process and additionally implement cuts on the invariant masses of
the W+ b and W- bbar pairs.Comment: Talk presented at the 35th International Conference of High Energy
Physics - ICHEP2010, July 22-28, 2010, Paris France. 4 pages, 2 figure
Choose Life! Early Quaker Women and Violence in Modernity
The peace testimony of the early Quakers was developed in a context where war, killing and death were a major preoccupation. In this article I show how Margaret Fell and other early Quaker women encouraged a choice of life rather than a preoccupation with death. While both women and men Friends developed the peace testimony, in the case of the men, the language of war (albeit the \u27Lamb\u27s War\u27) was retained, while many women (though not all) looked for language that was more nurturing and less violent. I suggest that it is the radical choice of life, not just the renunciation of violence, that is ultimately central to the peace testimony, especially in relation to its emphasis on justice and flourishing
Using Polymerization, Glass Structure, and Quasicrystalline Theory to Produce High Level Radioactive Borosilicate Glass Remotely: A 20+ Year Legacy
Vitrification is currently the most widely used technology for the treatment of high level radioactive wastes (HLW) throughout the world. Most of the nations that have generated HLW are immobilizing in borosilicate glass. One of the primary reasons that glass has become the most widely used immobilization media is the relative simplicity of the vitrification process, e.g. melt a highly variable waste with some glass forming additives such as SiO2 and B2O3 in the form of a premelted frit and pour the molten mixture into a stainless steel canister. Seal the canister before moisture can enter the canister (10’ tall by 2’ in diameter) so the canister does not corrode from the inside out. Glass has also become widely used for HLW is that due to the fact that the short range order (SRO) and medium range order (MRO) found in the structure of glass atomistically bonds the radionuclides and hazardous species in the waste. The SRO and MRO have also been found to govern the melt properties such as viscosity and resistivity of the melt and the crystallization potential and solubility of certain species. The molecular structure of the glass also controls the glass durability, i.e. the contaminant/radionuclide release, by establishing the distribution of ion exchange sites, hydrolysis sites, and the access of water to those sites. The molecular structure is flexible and hence accounts for the flexibility of glass formulations to HLW waste variability. Nuclear waste glasses melt between 1050-1150°C which minimizes the volatility of radioactive components such as 99Tc, 137Cs, and 129I. Nuclear waste glasses have good long term stability including irradiation resistance. Process control models were developed based on the molecular structure of glass, polymerization theory of glass, and quasicrystalline theory of glass crystallization. These models create a glass which is durable, pourable, and processable with 95% accuracy without knowing from batch to batch what the composition of the waste coming out of the storage tanks will be. These models have operated the Savannah River Site Defense Waste Processing Facility (SRS DWPF), which is the world’s largest HLW Joule heated ceramic melter, since 1996. This unique “feed forward” process control, which qualifies the durability, pourability, and processability of the waste plus glass additive mixture before it enters the melter, has enabled ~8000 tons of HLW glass and 4242 canisters to be produced since 1996 with only one melter replacement
A symmetry invariant integral on kappa-deformed spacetime
In this note we present an approach using both constructive and Hopf
algebraic methods to contribute to the not yet fully satisfactory definition of
an integral on kappa-deformed spacetime. The integral presented here is based
on the inner product of differential forms and it is shown that this integral
is explicitly invariant under the deformed symmetry structure.Comment: 16 page
The quantum Casimir operators of \Uq and their eigenvalues
We show that the quantum Casimir operators of the quantum linear group
constructed in early work of Bracken, Gould and Zhang together with one extra
central element generate the entire center of \Uq. As a by product of the
proof, we obtain intriguing new formulae for eigenvalues of these quantum
Casimir operators, which are expressed in terms of the characters of a class of
finite dimensional irreducible representations of the classical general linear
algebra.Comment: 10 page
Harmonic Analysis of Linear Fields on the Nilgeometric Cosmological Model
To analyze linear field equations on a locally homogeneous spacetime by means
of separation of variables, it is necessary to set up appropriate harmonics
according to its symmetry group. In this paper, the harmonics are presented for
a spatially compactified Bianchi II cosmological model -- the nilgeometric
model. Based on the group structure of the Bianchi II group (also known as the
Heisenberg group) and the compactified spatial topology, the irreducible
differential regular representations and the multiplicity of each irreducible
representation, as well as the explicit form of the harmonics are all
completely determined. They are also extended to vector harmonics. It is
demonstrated that the Klein-Gordon and Maxwell equations actually reduce to
systems of ODEs, with an asymptotic solution for a special case.Comment: 28 pages, no figures, revised version to appear in JM
Chaotic Accretion in a Non-Stationary Electromagnetic Field of a Slowly Rotating Compact Star
We investigate charge accretion in vicinity of a slowly rotating compact star
with a non-stationary electromagnetic field. Exact solutions to the general
relativistic Maxwell equations are obtained for a star formed of a highly
degenerate plasma with a gravitational field given by the linearized Kerr
metric. These solutions are used to formulate and then to study numerically the
equations of motion for a charged particle in star's vicinity using the
gravitoelectromagnetic force law. The analysis shows that close to the star
charge accretion does not always remain ordered. It is found that the magnetic
field plays the dominant role in the onset of chaos near the star's surface.Comment: 9 pages, 4 figure
Weak Boson Emission in Hadron Collider Processes
The O(alpha) virtual weak radiative corrections to many hadron collider
processes are known to become large and negative at high energies, due to the
appearance of Sudakov-like logarithms. At the same order in perturbation
theory, weak boson emission diagrams contribute. Since the W and Z bosons are
massive, the O(alpha) virtual weak radiative corrections and the contributions
from weak boson emission are separately finite. Thus, unlike in QED or QCD
calculations, there is no technical reason for including gauge boson emission
diagrams in calculations of electroweak radiative corrections. In most
calculations of the O(alpha) electroweak radiative corrections, weak boson
emission diagrams are therefore not taken into account. Another reason for not
including these diagrams is that they lead to final states which differ from
that of the original process. However, in experiment, one usually considers
partially inclusive final states. Weak boson emission diagrams thus should be
included in calculations of electroweak radiative corrections. In this paper, I
examine the role of weak boson emission in those processes at the Fermilab
Tevatron and the CERN LHC for which the one-loop electroweak radiative
corrections are known to become large at high energies (inclusive jet, isolated
photon, Z+1 jet, Drell-Yan, di-boson, t-bar t, and single top production). In
general, I find that the cross section for weak boson emission is substantial
at high energies and that weak boson emission and the O(alpha) virtual weak
radiative corrections partially cancel.Comment: revtex3, 41 pages, 16 figures, 3 table
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