2,273 research outputs found
Present and Future in Semileptonic B Decays
In this talk I review the status of our ability to extract the CKM matrix
elements |Vub| and |Vcb| from semileptonic decays. I will review both exclusive
and inclusive methods and put a strong emphasis on how to ensure keeping the
extractions model independent.Comment: 10 pages, Invited plenary talk presented at 9th International
Symposium on Heavy Flavor Physics, Caltech, Sep. 10-13, 200
Heavy Quark Fragmenting Jet Functions
Heavy quark fragmenting jet functions describe the fragmentation of a parton
into a jet containing a heavy quark, carrying a fraction of the jet momentum.
They are two-scale objects, sensitive to the heavy quark mass, , and to a
jet resolution variable, . We discuss how cross sections for heavy
flavor production at high transverse momentum can be expressed in terms of
heavy quark fragmenting jet functions, and how the properties of these
functions can be used to achieve a simultaneous resummation of logarithms of
the jet resolution variable, and logarithms of the quark mass. We calculate the
heavy quark fragmenting jet function at , and the gluon and light quark fragmenting jet functions into a
heavy quark, and , at . We verify that, in the limit in which the jet invariant mass is
much larger than , the logarithmic dependence of the fragmenting jet
functions on the quark mass is reproduced by the heavy quark fragmentation
functions. The fragmenting jet functions can thus be written as convolutions of
the fragmentation functions with the matching coefficients ,
which depend only on dynamics at the jet scale. We reproduce the known matching
coefficients at , and we obtain the
expressions of the coefficients and at
. Our calculation provides all the perturbative
ingredients for the simultaneous resummation of logarithms of and
.Comment: 48 pages, 11 figure
Polarization Effects in Standard Model Parton Distributions at Very High Energies
We update the earlier work of Refs. arXiv:1703.08562 and arXiv:1712.07147 on
parton distribution functions in the full Standard Model to include gauge boson
polarization, non-zero input electroweak boson PDFs and next-to-leading-order
resummation of large logarithms.Comment: 24 pages, 7 Figures. arXiv admin note: text overlap with
arXiv:1703.08562, arXiv:1806.1015
A numerical formulation of resummation in effective field theory
In this article we show how the resummation of infrared and collinear
logarithms within Soft-Collinear Effective Theory (SCET) can be formulated in a
way that makes it suitable for a Monte-Carlo implementation. This is done by
applying the techniques developed for automated resummation using the branching
formalism, which have resulted in the general resummation approach CAESAR/ARES.
This work builds a connection between the two resummation approaches, and paves
the way to automated resummation in SCET. As a case study we consider the
resummation of the thrust distribution in electron-positron collisions at
next-to-leading logarithm (NLL). However, the results presented here are easily
generalizable to more complicated observables and processes as well as to
higher orders in the logarithmic accuracy.Comment: 47 page
Precision determination of Vub
We review how to determine |Vub| from inclusive semileptonic B decay using
combined cuts on the leptonic and hadronic invariant masses to eliminate the b
-> c background. This leads to a determination of |Vub| with theoretical
uncertainty at the 5 -10% level.Comment: 5 pages, Talk presented by C. W. Bauer at the International
Europhysics Conference on High Energy Physics (HEP2001), Budapest, Hungary,
July 12-18 200
- …