= Sean Fleming
{c}
\b[Sean Fleming] is a theoretical physicist whose work develops and applies <effective field theory> to <quantum chromodynamics>. The University of Arizona's physics profile identifies him with research on separating the disparate energy scales that occur in strong-interaction measurements.<Sean Fleming profile at the University of Arizona>[Research Interests]{ref}
With <Christian W. Bauer>, <Dan Pirjol> and <Iain W. Stewart>, he coauthored a2001 construction of a theory for energetic <quarks> coupled to collinear and soft <gluons>.<An effective field theory for collinear and soft gluons: heavy to light decays by Christian W. Bauer and others>[byline and Abstract]{ref} His2006 overview discusses <soft-collinear effective theory> and applications to particular meson decays and a radiative-decay spectrum.<Soft Collinear Effective Theory by Sean Fleming>[Abstract]{ref} These works connect a scale-organized field theory with quantities inferred from particle observations.
An original calculation illustrates why <power counting> is useful. Suppose a dimensionless observable is modeled by
$$
A(\lambda)=A_0+c_1\lambda+c_2\lambda^2+\cdots.
$$
For chosen values $A_0=1$, $c_1=2$, $c_2=-1$ and $\lambda=0.1$, the first three displayed terms give1.19; retaining only the leading term gives1. The small parameter organizes corrections, but the coefficients still matter. At $c_1=20$ instead, the first correction is2, so a small $\lambda$ alone would not make that correction negligible. These invented coefficients are not a fit or a prediction from Fleming's papers.
A controlled expansion therefore needs both a scale hierarchy and a specification of which contributions have been retained. Fleming's institutional research statement describes effective theories as an organizing tool for disentangling scales rather than treating a complicated measurement as a one-scale calculation.<Sean Fleming profile at the University of Arizona>[Research Interests]{ref}
\Image[https://physics.arizona.edu/sites/default/files/styles/az_medium/public/2025-12/Sean-Fleming-Headshot-Modal.png.webp?itok=bxOYXYAC]
{title=Sean Fleming, identified on his University of Arizona physics profile}
{source=https://physics.arizona.edu/people/sean-fleming}
{width=300}
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