Supersymmetric contributions to muon g−2 and the electroweak precision measurements

Abstract

In view of the recent measurement of the muon g − 2 and finalization of the LEP electroweak data, we re-examine all the new particle contributions to those observables in the MSSM. The SM fits the latest electroweak data excellently with the observed top-quark mass and the Higgs-boson mass of around 100 GeV, and so does the MSSM in the decoupling limit. The MSSM gives a slightly better fit to the data than the SM (∆χ 2 min ∼ −2) when relatively light left-handed sleptons of mass ∼ 200 GeV and a light chargino of mixed higgsinowino character (µ/M 2 ∼ 1) with mass ∼ 100 GeV co-exist. The improvement in the fit diminishes quickly for wino-or higgsino-dominant charginos, for heavier charginos, and for lighter sleptons. We find that the MSSM contributions to the muon g − 2 is most efficient when the light chargino has a mixed character. If tan β < 10, the set of a light mixed chargino and light sleptons that is favored by the electroweak data is also favored by the g − 2 data for µ > 0. Models with light gauginos (µ/M 2 > 10) or light higgsinos (µ/M 2 < 0.1) give significant contributions to muon g − 2 only for large tan β( ∼ > 15).

The muon magnetic moment and supersymmetry

“…µ into the photon-loop contributions, the remaining chargino/neutralino and sfermion contributions, and the bosonic and fermionic contributions. The results show, however, that the photon-exchange contributions are larger than a SUSY,χ+ f,rest µ by a factor ≈ 3, in agreement with the discussion in section 2.3.1 and the error estimate (85). Likewise, the two-loop corrections from SM-like diagrams with fermionic or bosonic loops are in the expected range ≈ (0.1 .…”

“…In general, the charginoor sfermion-loop contributions with photon exchange can be the largest two-loop contributions, but in all SPS points they are suppressed by moderate values of tan β § For very low sfermion masses the parameter scenarios used in figure 11 (a) violate the experimental bounds, which is why the results displayed in figure 11 (a) are larger than the limits found in figure 11 (b) at M LOSP ≈ 100 GeV. by a factor ≈ 3, in agreement with the discussion in section 2.3.1 and the error estimate (85). Likewise, the two-loop corrections from SM-like diagrams with fermionic or bosonic loops are in the expected range ≈ (0.1 .…”

“…In 2001, the publication of the Brookhaven result [3] caused a lot of excitement since it showed a deviation of 43( 16) × 10 −10 (2.6σ) from the SM theory prediction at the time (which involved a sign error in the light-by-light contributions). Many authors interpreted this result as a possible signal for supersymmetry, and a µ was studied in general SUSY models [20,47,65,[73][74][75][76][77][78][79][80][81], with emphasis on correlations and implications for particular other observables [82][83][84][85][86][87][88], and special scenarios or extended models were considered [89][90][91][92][93][94][95][96]. A general conclusion was that significant constraints, in particular upper mass limits could be derived even in the general MSSM.…”

B→Xsl+lFrank1, Nie2 2002Phys. Rev. D151270View full textAdd to dashboardCite

“…We investigate next the dependence of the branching ratio and asym- [18] and consistent with b → sγ [1]. We present the results in Fig.…”

The soft supersymmetry-breaking Lagrangian: theory and applications

“…Indeed, the absence of a Higgs boson lighter than about 110 GeV implies |cos 2β| is very near unity, which implies tan β is larger than about 4. ‡ There are other hints of a lower limit of a few on tan β -the precision data from LEP, SLC, and the Tevatron is described a little better [148,149] if there are light superpartners and in particular if sneutrinos are significantly lighter than charged sleptons. Their masses-squared are separated by the SU(2) D term |cos 2β| m 2 W , so again the implication is that |cos 2β| is near unity.…”