Two-Loop Corrections to the Muon Magnetic Moment from Fermion/Sfermion Loops in the MSSM: Detailed Results

Recently, first results were presented for two-loop corrections to the muon (g-2) from fermion/sfermion loops in the MSSM. These corrections were shown to be generally large and even logarithmically enhanced for heavy sfermions. Here, full details of the calculation and analytical results are presented. Also, a very compact formula is provided which can be easily implemented and serves as a good approximation of the full result as a function of the fourteen most important input parameters. Finally, a thorough discussion of the numerical behaviour of the fermion/sfermion-loop corrections to (g-2)_\mu\ is given. The discussion includes the case of very heavy SUSY masses as well as experimentally allowed scenarios with very light SUSY masses.Comment: 56 pages, 20 figures. v2 is the journal version. The Mathematica code amu2Lapprox.m for the compact approximation formula can be obtained from http://iktp.tu-dresden.de/?id=theory-softwar

GM2Calc: Precise MSSM prediction for (g−2)(g - 2) of the muon

We present GM2Calc, a public C++ program for the calculation of MSSM contributions to the anomalous magnetic moment of the muon, $(g-2)_\mu$. The code computes $(g-2)_\mu$ precisely, by taking into account the latest two-loop corrections and by performing the calculation in a physical on-shell renormalization scheme. In particular the program includes a $\tan\beta$ resummation so that it is valid for arbitrarily high values of $\tan\beta$, as well as fermion/sfermion-loop corrections which lead to non-decoupling effects from heavy squarks. GM2Calc can be run with a standard SLHA input file, internally converting the input into on-shell parameters. Alternatively, input parameters may be specified directly in this on-shell scheme. In both cases the input file allows one to switch on/off individual contributions to study their relative impact. This paper also provides typical usage examples not only in conjunction with spectrum generators and plotting programs but also as C++ subroutines linked to other programs.Comment: 27 pages, 4 figures, 4 listings; version sent to EPJ

Aspectos da função beta da teoria de Yang-Mills supersimétrica

Exportado OPUSMade available in DSpace on 2019-08-11T01:11:42Z (GMT). No. of bitstreams: 1 tese.pdf: 358245 bytes, checksum: 9cf9adb369a980995540a56749d95982 (MD5) Previous issue date: 12Desde os trabalhos pioneiros existe uma controvérsia sobre a origem das correções radiativas para a função da Teoria de Yang-Mills supersimétrica. Em teorias supersimétricas as anomalias da corrente quiral e do traço do tensor, energia-momento estão relacionadas. Enquanto a primeira obedece ao terorema de Adler-Bardeen e é exata em um laço, a segunda é proporcional à função e cálculos explícitos de encontram contribuições de ordens mais altas. A este conflito dá-se o nome de problema de anomalia. Neste trabalho calculamos a função da Teoria de Yang-Mills supersimétrica N = 1 pura através da Regularização Implícita até dois laços. Apesar da parte divergente ultravioleta em dois laços ser nula, encontramos um coeficiente da função de segunda ordem diferente de zero através da equação do grupo de renormalização. Esclarecemos o papel de divergências infravermelhas separando-as consistentemente das ultravioletas. De acordo com nossos cálculos, divergências infravermelhas fora da concha, não tem nenhum papel na obtenção da função como esperado. Entretanto, divergências infravermelhas na concha são importantes.Since the pioneering works there exists a controversy about the origin of the radiative contribuituions to the supersymmetric Yang-Mills beta function. In supersymmetric theories the chiral anomaly and the trace anomaly are related. While the former is exact in one loop order due to the Adler-Bardeen theorem the latter is proportional to the beta function and explicit calculations of find higher order contributions. This conflict is known as anomaly puzzle. In this work we calculate the pure N = 1supersymmetric Yang-Mills beta function up to two loops using Implicit Regularization. Despite the two-loop ultraviolet divergent piece being null we find a nonzero second order beta function coefficient through the renormalization group equation. We shed light on the infrared divergences role consistently separating them from the ultraviolet ones. According with our calculation, off-shell infrared divergences have no role obtaining the beta function - as one could expect. However on-shell infrared divergences are important