2,508,667 research outputs found
Threshold graph limits and random threshold graphs
We study the limit theory of large threshold graphs and apply this to a
variety of models for random threshold graphs. The results give a nice set of
examples for the emerging theory of graph limits.Comment: 47 pages, 8 figure
Crossed Threshold Resummation
We show that certain general properties of threshold and joint resummations
in Drell-Yan cross sections hold as well for their crossed analogs in
semi-inclusive deep-inelastic scattering and double-inclusive leptonic
annihilation. We show that all plus-distribution corrections near threshold
show the same structure, and are determined to all logarithmic order by two
anomalous dimensions, one of which is a generalization of the D-term previously
derived in Drell-Yan. We also discuss the possibility of universality in power
corrections implied by the resummation.Comment: 8 page
Universal threshold enhancement
By assuming certain analytic properties of the propagator, it is shown that
universal features of the spectral function including threshold enhancement
arise if a pole describing a particle at high temperature approaches in the
complex energy plane the threshold position of its two-body decay with the
variation of T. The case is considered, when one can disregard any other decay
processes. The quality of the proposed description is demonstrated by comparing
it with the detailed large N solution of the linear sigma model around the
pole-threshold coincidence.Comment: 4 pages, 2 figure
Threshold Factorization Redux
We reanalyze the factorization theorems for Drell-Yan process and for deep
inelastic scattering near threshold, as constructed in the framework of the
soft-collinear effective theory (SCET), from a new, consistent perspective. In
order to formulate the factorization near threshold in SCET, we should include
an additional degree of freedom with small energy, collinear to the beam
direction. The corresponding collinear-soft mode is included to describe the
parton distribution function (PDF) near threshold. The soft function is
modified by subtracting the contribution of the collinear-soft modes in order
to avoid double counting on the overlap region. As a result, the proper soft
function becomes infrared finite, and all the factorized parts are free of
rapidity divergence. Furthermore, the separation of the relevant scales in each
factorized part becomes manifest. We apply the same idea to the dihadron
production in annihilation near threshold, and show that the
resultant soft function is also free of infrared and rapidity divergences.Comment: 20 pages, 2 figures; matches published versio
Top Threshold Physics
Running a future Linear Collider at the top pair threshold allows for precise
measurements of the mass, the widths and the couplings of the top quark. I give
a nontechnical review on recent theoretical developments and the theory status
in top threshold physics concerning QCD corrections and top quark finite
lifetime and electroweak effects. I also discuss threshold physics in the
context of measurements of the top Yukawa coupling from
and of squark pair production.Comment: 13 pages, 6 figures, PoS style. Invited talk presented at the
International Workshop on Top Quark Physics, Coimbra, Portugal, 12-15 Jan
200
- …