Precise prediction for the W boson mass in the MRSSM

The mass of the W boson, $M_W$, plays a central role for high-precision tests of the electroweak theory. Confronting precise theoretical predictions with the accurately measured experimental value provides a high sensitivity to quantum effects of the theory entering via loop contributions. The currently most accurate prediction for the W boson mass in the Minimal R-symmetric Supersymmetric Standard Model (MRSSM) is presented. Employing the on-shell scheme, it combines all numerically relevant contributions that are known in the Standard Model (SM) in a consistent way with all MRSSM one-loop corrections. Special care is taken in the treatment of the triplet scalar vacuum expectation value $v_T$ that enters the prediction for $M_W$ already at lowest order. In the numerical analysis the decoupling properties of the supersymmetric loop contributions and the comparison with the MSSM are investigated. Potentially large numerical effects of the MRSSM-specific $\Lambda$ superpotential couplings are highlighted. The comparison with existing results in the literature is discussed.Comment: 35 pages, 9 figures; Updated to JHEP version with minor change

Can greater central bank accountability defuse the conflict between the Bundesverfassungsgericht and the European Central Bank?

Germany’s constitutional court recently ruled that asset purchases conducted by the European Central Bank could be incompatible with the German constitution. As Sebastian Diessner explains, the subsequent rift has prompted calls for greater accountability in ECB decision-making, potentially with representatives from Germany’s central bank, the Bundesbank, being obliged to explain ECB decisions in the Bundestag. He writes that while there should be no illusions that such a measure could defuse the conflict entirely, an honest debate about central bank accountability in Europe is long overdue

LSE Continental Breakfast 5: Britain's financial obligations to the EU

How much does Britain owe the EU? What are its legal obligations? Is the European Commission right to demand that the vexed issue of Britain's 'divorce bill' is settled before trade talks can begin? Britain's financial obligations to the EU were the subject of the fifth Continental Breakfast discussion at the LSE - held under Chatham House rules, so participants ..

Squark production in R-symmetric SUSY with Dirac gluinos: NLO corrections

R-symmetry leads to a distinct realisation of SUSY with a significantly modified coloured sector featuring a Dirac gluino and a scalar colour octet (sgluon). We present the impact of R-symmetry on squark production at the 13 TeV LHC. We study the total cross sections and their NLO corrections from all strongly interacting states, their dependence on the Dirac gluino mass and sgluon mass as well as their systematics for selected benchmark points. We find that tree-level cross sections in the R-symmetric model are reduced compared to the MSSM but the NLO K-factors are generally larger in the order of ten to twenty per cent. In the course of this work we derive the required DREG $\to$ DRED transition counterterms and necessary on-shell renormalisation constants. The real corrections are treated using FKS subtraction, with results cross checked against an independent calculation employing the two cut phase space slicing method.Comment: 46 pages, 15 figures; updated to match published versio

The ECB’s capital key needs rethinking – and Brexit has everything to do with it

The so called ‘capital key’ used by the European Central Bank is due to be reviewed, with two important meetings coming up on 6 and 13 December. Sebastian Diessner explains that while in the past this has been viewed as a largely technical process, this time around the issue will have heightened political significance for two reasons in particular: the UK’s upcoming departure from the EU, and the current stand-off between the EU’s institutions and Italy’s government

Increasing the transparency of the ECB could do more harm than good

Earlier this year, the European Central Bank agreed to release minutes of its governing council meetings in response to criticism over the lack of transparency in its decision-making. Sebastian Diessner writes that while there are good reasons to support the ECB becoming more transparent, lessons should also be learned from the experiences of other central banks. He notes that too much transparency can inhibit discussions and thereby lead to less effective monetary policy overall

Two-loop correction to the Higgs boson mass in the MRSSM

We present the impact of two-loop corrections on the mass of the lightest Higgs boson in the Minimal R-symmetric Supersymmetric Standard Model (MRSSM). These shift the Higgs boson mass up by typically 5 GeV or more. The dominant corrections arise from strong interactions, from the gluon and its N=2 superpartners, the sgluon and Dirac gluino, and these corrections further increase with large Dirac gluino mass. The two-loop contributions governed purely by Yukawa couplings and the MRSSM $\lambda,\Lambda$ parameters are smaller. We also update an earlier analysis [Diessner:2014ksa], which showed that the MRSSM can accommodate the measured Higgs and W boson masses. Including the two-loop corrections increases the parameter space where the theory prediction agrees with the measurement.Comment: To be submitted to "Supersymmetry beyond the NMSSM", Advances in High Energy Physic

More questions than answers? The EU’s new Anti-Money Laundering Authority

The EU is set to establish a new Anti-Money Laundering Authority next year. Sebastian Diessner writes that while the new authority is a step in the right direction, there remain more questions than answers over how it will function and where it will be based