1,092 research outputs found
Resummations in QCD hard-scattering at large and small x
We discuss different resummations of large logarithms that arise in
hard-scattering cross sections of quarks and gluons in regions of large and
small x. The large-x logarithms are typically dominant near threshold for the
production of a specified final state. These soft and collinear gluon
corrections produce large enhancements of the cross section for many processes,
notably top quark and Higgs production, and typically the higher-order
corrections reduce the factorization and renormalization scale dependence of
the cross section. The small-x logarithms are dominant in the regime where the
momentum transfer of the hard sub-process is much smaller than the total
collision energy. These logarithms are important to describe multijet final
states in deep inelastic scattering and hadron colliders, and in the study of
parton distribution functions. The resummations at small and large x are linked
by the eikonal approximation and are dominated by soft gluon anomalous
dimensions. We will review their role in both contexts and provide some
explicit calculations at one and two loops.Comment: 36 pages, 12 figures, invited contribution to the edited book "The
Physics of Quarks"; Eqs. 31 and 47 corrected, references update
Probing Unified Origin of Dark Matter and Baryon Asymmetry at PAMELA/Fermi
We propose an unified model of dark matter and baryon asymmetry in a
lepto-philic world above the electroweak scale. We provide an example where the
inflaton decay products subsequently generate a lepton asymmetry and a dark
matter abundance with an unique coupling in the early universe, while the
present day decay of the dark matter through the same coupling gives rise the
observed cosmic ray anomalies at PAMELA and Fermi Large Area Telescope.Comment: 6 pages (minor revision), revtex, 3 figure
The role of 'S' level mathematics
The role of 'S' level mathematic
Status of Eikonal Two-Loop Calculations with Massive Quarks
We present results for two-loop diagrams with massive quarks in the eikonal
approximation. Explicit expressions are given for the UV poles in dimensional
regularization of several of the required integrals.Comment: 5 pages, 3 figures; presented at DIS 2008, London, England, April
7-11, 2008; corrections in I_2, I_2^UV, and I_ql^U
Oral mucosal progenitor cell clones resist In Vitro myogenic differentiation
Abstract
Progenitor cells derived from the oral mucosa lamina propria (OMLP-PCs) demonstrate an ability to differentiate into tissue lineages removed from their anatomical origin. This clonally derived population of neural-crest cells have demonstrated potential to differentiate along mesenchymal and neuronal cell lineages.
Objective
Significant efforts are being made to generate functioning muscle constructs for use in research and clinical tissue engineering. In this study we aimed to determine the myogenic properties of clonal populations of expanded OMLP-PCs.
Design
PCs were subject to several in vitro culture conditions in an attempt to drive myogenic conversion. Methodologies include use of demethylation gene-modifying reagents, mechanical conditioning of tissue culture substrates, tuneable polyacrylamide gels and a 3-dimensional construct as well as published myogenic media compositions. PCR and immunostaining for the muscle cell markers Desmin and MyoD1 were used to assess muscle differentiation
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