This White Paper briefly reviews the present status of the muon (g-2) experiment and the physics motivation for a new effort. The present comparison between experiment and theory indicates a tantalizing $3.4 \sigma$ deviation. An improvement in precision on this comparison by a factor of 2--with the central value remaining unchanged--will exceed the ``discovery'' threshold, with a sensitivity above $6 \sigma$. The 2.5-fold reduction improvement goal of the new Brookhaven E969 experiment, along with continued steady reduction of the standard model theory uncertainty, will achieve this more definitive test.
Already, the (g-2) result is arguably the most compelling indicator of physics beyond the standard model and, at the very least, it represents a major constraint for speculative new theories such as supersymmetry or extra dimensions. In this report, we summarize the present experimental status and provide an up-to-date accounting of the standard model theory, including the expectations for improvement in the hadronic contributions, which dominate the overall uncertainty. Our primary focus is on the physics case that motivates improved experimental and theoretical efforts. Accordingly, we give examples of specific new-physics implications in the context of direct searches at the LHC as well as general arguments about the role of an improved (g-2) measurement. A brief summary of the plans for an upgraded effort complete the report.
[1]
E. al.,et al.
E+e-→K+K-π+π-, K+K-π0π0 and K+K-K+K- cross sections measured with initial-state radiation
,
2007,
0704.0630.
[2]
J. Prades,et al.
Status of the hadronic light-by-light contribution to the muon anomalous magnetic moment
,
2007,
hep-ph/0701240.
[3]
D. Stöckinger.
The muon magnetic moment and supersymmetry
,
2006
.
[4]
D. Stockinger.
The Muon Magnetic Moment and Supersymmetry
,
2006,
hep-ph/0609168.
[5]
B. Webber,et al.
Distinguishing Spins in Supersymmetric and Universal Extra Dimension Models at the Large Hadron Collider
,
2005,
hep-ph/0507170.
[6]
R. Lafaye,et al.
SFITTER: SUSY parameter analysis at LHC and LC
,
2004,
hep-ph/0404282.
[7]
E. Sichtermann,et al.
Muon g-2
,
2003,
hep-ex/0309008.
[8]
B. Dobrescu,et al.
Universal extra dimensions and the muon magnetic moment
,
2001,
hep-ph/0106140.
[9]
M. Carena,et al.
Constraints on supersymmetric models from the muon anomalous magnetic moment
,
1996,
hep-ph/9610233.
[10]
Ilman,et al.
SFITTER: SUSY Parameter Analysis at LHC and LC
,
2004
.