In quantum field theory, soft-collinear effective
theory (or SCET) is a theoretical framework
for doing calculations that involve interacting
particles carrying widely different energies.
The motivation for developing SCET was to
control the infrared divergences that occur
in quantum chromodynamics (QCD) calculations
that involve particles that are soft—carrying
much lower energy or momentum than other particles
in the process—or collinear—traveling
in the same direction as another particle
in the process. SCET is an effective theory
for highly energetic quarks interacting with
collinear and/or soft gluons. It has been
used for calculations of the decays of B mesons
(quark-antiquark bound states involving a
bottom quark) and the properties of jets (sprays
of hadrons that emerge from particle collisions
when a quark or gluon is produced). SCET has
also been used to calculate electroweak interactions
in Higgs boson production.The new feature
of SCET is its ability to handle more than
one soft energy scale. For example, processes
involving quarks carrying a high energy Q
interacting with gluons have two soft scales:
the transverse momentum pT of the collinear
particles, plus the even softer scale pT2/Q.
SCET provides a power-counting formalism for
doing perturbation theory in the small parameter
ΛQCD/Q.
== External links ==
Original papers:
C.W. Bauer, S. Fleming, M. Luke, "Summing
Sudakov logarithms in
B
→
X
s
γ
{\displaystyle B\rightarrow X_{s}\gamma }
in effective field theory", Phys. Rev. D63,
014006 (2000), arXiv:hep-ph/0005275.
C.W. Bauer, S. Fleming, D. Pirjol, and I.W.
Stewart, "An effective field theory for collinear
and soft gluons: heavy to light decays", Phys.
Rev. D63, 114020 (2001), arXiv:hep-ph/0011336.
C.W. Bauer, I.W. Stewart, "Invariant Operators
in Collinear Effective Theory", Phys. Lett.
B516 (2001), 134–142, arXiv:hep-ph/0107001.
C.W. Bauer, D. Pirjol, and I.W. Stewart, "Soft-collinear
factorization in effective field theory",
Phys. Rev. D65, 054022 (2002), arXiv:hep-ph/0109045.
C.W. Bauer, D. Pirjol, and I.W. Stewart, "Power
counting in the soft-collinear effective theory",
Phys. Rev. D66, 054005 (2002), arXiv:hep-ph/0205289
