Z boson pole mass at two-loop order in the pure MS-bar scheme

I obtain the complex pole squared mass of the Z boson at full two-loop order in the Standard Model in the pure MS-bar renormalization scheme. The input parameters are the running gauge couplings, the top-quark Yukawa coupling, the Higgs self-coupling, and the vacuum expectation value that minimizes the Landau gauge effective potential. The effects of non-zero Goldstone boson mass are resummed. Within a reasonable range of renormalization scale choices, the scale dependence of the computed pole mass is found to be comparable to the current experimental uncertainty, but the true theoretical error is likely somewhat larger.Comment: 15 pages. arXiv admin note: text overlap with arXiv:1503.0378

Non-standard supersymmetry breaking and Dirac gaugino masses without supersoftness

I consider models in which non-standard supersymmetry breaking terms, including Dirac gaugino masses, arise from F-term breaking mediated by operators with a $1/M^3$ suppression. In these models, the supersoft properties found in the case of D-term breaking are absent in general, but can be obtained as a special case that is a fixed point of the renormalization group equations. The $\mu$ term is replaced by three distinct supersymmetry-breaking parameters, decoupling the Higgs scalar potential from the Higgsino masses. Both holomorphic and non-holomorphic scalar cubic interactions with minimal flavor violation are induced in the supersymmetric Standard Model Lagrangian.Comment: 22 pages. v2: references adde

Quasi-fixed points from scalar sequestering and the little hierarchy problem in supersymmetry

In supersymmetric models with scalar sequestering, superconformal strong dynamics in the hidden sector suppresses the low-energy couplings of mass dimension two, compared to the squares of the dimension one parameters. Taking into account restrictions on the anomalous dimensions in superconformal theories, I point out that the interplay between the hidden and visible sector renormalizations gives rise to quasi-fixed point running for the supersymmetric Standard Model squared mass parameters, rather than driving them to 0. The extent to which this dynamics can ameliorate the little hierarchy problem in supersymmetry is studied. Models of this type in which the gaugino masses do not unify are arguably more natural, and are certainly more likely to be accessible, eventually, to the Large Hadron Collider.Comment: 23 page

U.S. Antitrust and EU Competition Policy: Where has the Former Been, Where is the Latter Going?

The earliest U.S. antitrust laws were adopted after technological changes — most importantly, the development of a national railway network — made the U.S. political union a single economic market. They were adopted with the stated, and no doubt largely sincere, purposes of preventing collusion and strategic entry-deterring behavior. Early application of the antitrust laws relied on a rule of competition to determine whether business conduct was or was not permitted. This has evolved into an explicit evaluation of the impact of businesses practices on consumer welfare, conceived of and measured in an economic sense. EU competition policy was adopted in advance of economic integration. It differed sharply from the traditional policies of the original EC6 member states toward business behavior. It was adopted with the stated, and most likely sincere, purpose of furthering economic integration, and to this end prohibited practices that were seen as distorting competition. Early applications of competition policy, particularly in the European Coal and Steel Community, may have had perverse effects. There are indications of an evolution towards an economic performance standard in the European Union as well.US antitrust policy, EU competition policy, European Union, Economic governance, regulation