Andreas S. Kronfeld's Home Page


Most of my research focuses on lattice gauge theory, particularly on the quest to make reliable calculations of hadronic matrix elements. These are needed, in particular, to interpret experiments studying the B meson at Fermilab's Tevatron, KEK's KEK-B, and SLAC's PEP-II accelerators. A large part of this effort is devoted towards developing and improving methodology (reviewed here), but it is also important to do calculations of broad interest (reviewed here). As an outgrowth of this work, I have been involved some collaborative efforts between theorists and experimentalists, organizing a workshop on B Physics at the Tevatron, and participating in CERN's CKM Unitarity Triangle Workshop.

In recent years I have also been involved in studies of the physics potential of linear e+e- colliders.

Curriculum vita and list of publications (also available as one sequential list, or try inSPIRE HEP), as of July 2013. Briefly, I received my Ph.D. from Cornell University in 1985, after which I was a post-doc at DESY for three years. I have been at Fermilab since 1988.


Lattice QCD and Flavor Physics

The Golden Era of Lattice QCD

In 2003, a collaboration of Collaborations discovered that lattice QCD with 2+1 flavors of sea quarks agreed with experiment for a wide variety of gold-plated quantities: This striking development, among other things, led to a vigorous dialogue about the theoretical foundations of the way the sea quarks are treated in this paper (namely, with rooted, staggered fermions). In 2007 I wrote a summary of the arguments in favor, a list of recent theoretical papers, and a refutation a specific claims against.

Predictions from Lattice QCD

In 2004–2005 we then aimed to predict several other gold-plated quantities: These results were later confirmed by several experimental measurements. This development is summarized in: As the measurements of one of these quantities—the decay constant of the Ds meson—improved, the measurement deviated from the calculation (of another group) by 3.8σ. The D+, K, and π decay constants (which are harder to control) remain in agreement. The deviation can be interpreted as a signal of non-Standard physics: Clearly the discrepancy calls for other lattice groups to compute the Ds decay constant with other methods, and for the experimental measurements to be improved.

Review Papers and Review Talks at Conferences

Some reviews that may be of interest: Write-ups of talks aimed at experimenters:

Theoretical Foundations of Heavy Quarks on the Lattice

It is a challenge to treat the heavy b quark in lattice gauge theory, because its mass is above the ultraviolet cutoff of the lattice. We have developed a framework for solving the problem, marrying aspects of conventional lattice QCD with the simplifications of the heavy-quark limit. A suite of computer codes for the radiative corrections computed in the second- and third-to-last papers is available at LatHQ2QCD.

A by-product of the second paper was a proof that the pole mass of a quark is infrared-finite and gauge-invariant, order by order in perturbative QCD. See The Perturbative Pole Mass in QCD.

We have also tested how well perturbation theory works for short-distance coefficients in Perturbative Calculation of O(a) Improvement Coefficients, with Harada, Hashimoto, and Onogi.

Phenomenological Applications (in the Quenched Approximation)

These theoretical developments were informed by and fed into a series of papers on quantities of phenomenological interest Although these calculations omit sea quarks (aka the quenched approximation) and are obsolete quantitatively, they set a standard for thorough analysis of all the uncertainties that arise in lattice gauge theory.

Here are two papers that are also of interest to Standard Model phenomenology, but which hinge more on the property of light quarks

For completeness, here are some results that have been presented only at Lattice conferences: You can find out more about some of my collaborators from their web pages: Aida El-Khadra, Paul Mackenzie, Tetsuya Onogi, Sinead Ryan, and Jim Simone.

Linear Collider Studies

Since 2004 I have been a delegate on the Organizing Commmittee of the World-Wide Study of the Physics and Detectors for Future e+e- Colliders (WWS-OC).

Earlier I was a convener (for top quarks, and the Higgs bosons) in the North American study.

With Slawomir Tkaczyk I coordinated a local study within Fermilab for Director Michael Witherell.

Convenient links

Report of study commissioned by Fermilab Directorate

My talks on the subject


Address:

Theoretical Physics Group
Fermi National Accelerator Laboratory
P.O. Box 500
Batavia, IL 60510-0500
U. S. A.
Telephone: (630) 840-3753, fax: (630) 840-5435
e-mail: ask@fnal.gov

A picture of me in my office.

From October 10 to December 23, 1995, I visited Nordita.

From February 1 to April 30, 2001, I visited Tsukuba University.


Miscellaneous:

Home telephone: (630) 357-3755

Other Kronfelds on the Internet



Author: Andreas Kronfeld
Revised: 19 March 2008
Created: November 1995