The two-loop axial anomaly in N = 1 supersymmetric Yang-Mills theory

We calculate the two loop correction to the divergence of the axial current inN = 1 supersymmetric Yang-Mills theory. We find that, if we use supersymmetric dimensional regularization, the anomaly is proportional to the [beta]-function, a result we interpret as evidence that the supermultiplet nature of the trace, axial and supersymmetry anomalies persists at the two- loop level. Thus it appears that the Adler-Bardeen theorem is not valid in supersymmetric theories.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24036/1/0000285.pd

Fluids, evaporation and precipitates at Gale Crater

The Mars Science Laboratory (MSL) mission landed in Gale Crater, Mars, on 6th August 2012, and has explored the Yellowknife Bay area. The detailed mineralogical and sedimentological studies provide a unique opportunity to characterise the secondary fluids associated with this habitable environment

Muon anomalous magnetic moment in string inspired extended family models

We propose a standard model minimal extension with two lepton weak SU(2) doublets and a scalar singlet to explain the deviation of the measured anomalous magnetic moment of the muon from the standard model expectation. This scheme can be naturally motivated in string inspired models such as E_6 and AdS/CFT.Comment: 9 pages, RevTeX, 2 figures, version to be published in Phys. Rev.

Dark Force Detection in Low Energy e-p Collisions

We study the prospects for detecting a light boson X with mass m_X < 100 MeV at a low energy electron-proton collider. We focus on the case where X dominantly decays to e+ e- as motivated by recent "dark force" models. In order to evade direct and indirect constraints, X must have small couplings to the standard model (alpha_X 10 MeV). By comparing the signal and background cross sections for the e- p e+ e- final state, we conclude that dark force detection requires an integrated luminosity of around 1 inverse attobarn, achievable with a forthcoming JLab proposal.Comment: 38 pages, 19 figures; v2, references adde

Very light CP-odd scalar in the Two-Higgs-Doublet Model

We show that a general two-Higgs-doublet model (THDM) with a very light CP-odd scalar (A) can be compatible with the rho parameter, Br(b --> s\gamma), R_b, A_b, (g-2) of muon, Br(Upsilon --> A gamma), and the direct search via the Yukawa process at LEP. For its mass around 0.2 GeV, the muon (g-2) and Br(Upsilon --> A \gamma) data require tan(beta) to be about 1. Consequently, A can behave like a fermiophobic CP-odd scalar and predominantly decay into a photon pair ("gamma gamma"), which registers in detectors of high energy collider experiments as a single photon signature when the momentum of A is large. We compute the partial decay width of Z --> A A A and the production rate of f \bar{f} --> Z A A --> Z +"gamma gamma", f^' {\bar f} --> W^{\pm} A A --> W^\pm + "gamma gamma" and f \bar f --> H^+ H^- --> W^+ W^- A A --> W^+ W^- + "gamma gamma" at high energy colliders such as LEP, Tevatron, LHC, and future Linear Colliders. Other production mechanisms of a light A, such as gg --> h --> AA --> "gamma gamma", are also discussed.Comment: Some improvementes, references updated, 3 new figures, one new appendix, abstract and conclusions unchaged. Version to appear in Physical Review

Muon anomalous magnetic moment in the standard model with two Higgs doublets

The muon anomalous magnetic moment is investigated in the standard model with two Higgs doublets (S2HDM) motivated from spontaneous CP violation. Thus all the effective Yukawa couplings become complex. As a consequence of the non-zero phase in the couplings, the one loop contribution from the neutral scalar bosons could be positive and negative relying on the CP phases. The interference between one and two loop diagrams can be constructive in a large parameter space of CP-phases. This will result in a significant contribution to muon anomalous magnetic moment even in the flavor conserving process with a heavy neutral scalar boson ($m_h \sim$ 200 GeV) once the effective muon Yukawa coupling is large ($|\xi_\mu|\sim 50$). In general, the one loop contributions from lepton flavor changing scalar interactions become more important. In particular, when all contributions are positive in a reasonable parameter space of CP phases, the recently reported 2.6 sigma experiment vs. theory deviation can be easily explained even for a heavy scalar boson with a relative small Yukawa coupling in the S2HDM.Comment: 8 pages, RevTex file, 5 figures, published version Phys. Rev. D 54 (2001) 11501