582 research outputs found
All-Order Corrections To Higgs Boson Production In Association With Jets
We present a new framework for calculating multi-jet observables. The
framework is based on the factorisation of scattering amplitudes in the
kinematical limit of large invariant mass between all particles. We show that
by constraining the analyticity of scattering amplitudes away from this limits,
we get good agreement order by order with the full, fixed order perturbative
calculation at the low orders where these are available, and therefore get firm
predictions on the all-order behaviour. As an example, we study Higgs boson
production through gluon fusion in association with at least two jets at the
LHC.Comment: Invited talk at 44th Rencontres de Moriond on QCD and High Energy
Interactions, La Thuile, Valle d'Aosta, Italy, 14-21 Mar 200
A Closer look at the analysis of NLL BFKL.
The initial analyses of the next-to-leading logarithmic corrections to the BFKL kernel were
very discouraging. Encouraged by the success of new methods in the analysis of the BFKL
equation at full NLL accuracy we demonstrate in this talk how some of the initial conclusions
were based on a breakdown of the tools used in the analysis rather than the framework itself
A New approach to inclusive decay spectra.
The main obstacle in describing inclusive decay spectra in QCD â which, in particular, limits
the precision in extrapolating the measured ÂŻB ââ Xs
rate to the full phase space as well as
in extracting |Vub| from inclusive measurements of charmless semileptonic decays â is their
sensitivity to the non-perturbative momentum distribution of the heavy quark in the meson.
We show that, despite this sensitivity, resummed perturbation theory has high predictive
power. Conventional Sudakovâresummed perturbation theory describing the decay of an onshell
heavy quark yields a divergent expansion. Detailed understanding of this divergence
in terms of infrared renormalons has paved the way for making quantitative predictions. In
particular, the leading renormalon ambiguity cancels out between the Sudakov factor and
the quark pole mass. This cancellation requires renormalon resummation but involves no
non-perturbative information. Additional effects due to the Fermi motion of the quark in
the meson can be systematically taken into account through power corrections, which are only
important near the physical endpoint. This way the moments of the ÂŻB ââ Xs
spectrum with
experimentallyâaccessible cuts â which had been so far just parametrized â were recently
computed by perturbative means. At Moriond these predictions were confronted with new
data from BaBar
All-Order Corrections and Multi-Jet Rates
We discuss results from a recently proposed all-order description of hard,
radiative corrections to certain multi-jet processes at hadron colliders. The
description is based on obtaining an all-order estimate of the t-channel
singularities of scattering amplitudes. As a simple example, we illustrate the
similarities between qQ and qg-scattering. In particular, we discuss how at
tree-level, all non-suppressed helicity-amplitudes for these processes consist
of a pure t-channel pole. This structure is used in the construction of
all-order approximations.Comment: 6 pages. Talk given at RADCOR 2009 - 9th International Symposium on
Radiative Corrections (Applications of Quantum Field Theory to
Phenomenology), October 25 - 30 2009, Ascona, Switzerlan
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A Study of the gluon ladder in diffractive processes.
The solution to the nonâforward BFKL equation in the Leading Logarithmic approximation
is expressed in terms of a sum of iterations of its kernel directly in transverse momentum
and rapidity space. Several studies of the nonâforward solution are performed both at the
level of the gluon Greenâs function and for a toy crossâsection, including an analysis of the
diffusion properties as found in this approach. The method developed in this paper allows
for a direct inspection of the momenta in the BFKL ladder, and can be applied to solving
the nonâforward BFKL equation to nextâtoâleading logarithmic accuracy, when the corresponding
kernel is available
New possibilities in the study of NLL BFKL.
The high energy limit of scattering processes in QCD is, at least on the purely theoretical
level, described by the BFKL equation. However, many phenomenological studies of BFKL
fail miserably when confronted with data. In this talk we will briefly review the application of
(LL) BFKL in phenomenology, and critically examine the application of LL eigenfunctions in
the study of the NLL BFKL kernel. We then introduce a recently proposed iterative solution
of the NLL BFKL equation that allows for a detailed study of physical properties of the BFKL
evolution
Multi-Jet Processes in the High Energy Limit of QCD.
We discuss how the multi-Regge factorisation of QCD amplitudes can be used in
the study of multi-jet processes at colliders. We describe how the next-to-leading
logarithmic (NLL) BFKL evolution can be combined with energy and momentum
conservation. By recalculating the quark contribution to the next-to-leading logarithmic
corrections to the BFKL kernel we can study several properties of the NLL
corrections. We demonstrate that in the standard analysis, the NLL corrections
to a single gluon emission includes contributions from significantly more energetic
quarkâanti-quark configurations, something that could contribute to the sizable
NLL corrections in the standard BFKL analysis
The use of derivatives to hedge embedded options : the case of pension institutions in Denmark
The main purpose of this paper is to examine the growing use of derivatives by Danish pension institutions as a risk management tool to hedge embedded options on their balance sheets. Throughout the 1980s and 1990s it was a widespread practice for Danish pension institutions to guarantee a minimum interest rate on new pension policies. With the new millennium global interest rates declined steeply and equity markets came crashing down. Suddenly the guarantees on pension contracts were in the money. The policies already written could not be changed, leaving liabilities and assets mismatched, profits in the red, and capital reserves drained. Out of necessity, and in some cases virtue, Danish pension institutions turned in scale to derivatives, allowing for a more active approach to hedging, asset and liability management, and even profit generation. Through the use of derivatives, pension institutions have avoided the need to renegotiate their guaranteed contracts with policy holders. They have succeeded as an industry in transforming their pay-off curves and haveemerged with better matched asset/liability positions and lower exposure to interest rate risk. But the expanded use of derivatives also raises some risk management and regulatory issues, such as operational and counterparty risks as well as effective internal control systems and regulatory oversight.Investment and Investment Climate,Economic Theory&Research,Insurance&Risk Mitigation,Non Bank Financial Institutions,Settlement of Investment Disputes
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Solving the BFKL equation in the next-to-leading approximation.
The BalitskyâFadinâKuraevâLipatov equation in the nextâtoâleading logarithmic approximation
is solved using an iterative method. We derive the solution for forward
scattering with all conformal spins. A discussion of the infrared finiteness of the
results is included
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