47 research outputs found
Matching renormalisable couplings: simple schemes and a plot
We discuss different choices that can be made when matching a general
high-energy theory -- with the restriction that it should not contain heavy
gauge bosons -- onto a general renormalisable effective field theory at one
loop, with particular attention to the quartic scalar couplings and Yukawa
couplings. This includes a generalisation of the counterterm scheme that was
found to be useful in the case of high-scale/split supersymmetry, but we show
the important differences when there are new heavy scalar fields in singlet or
triplet representations of . We also analytically compare our methods
and choices with the approach of matching pole masses, proving the equivalence
with one of our choices. We outline how to make the extraction of quartic
couplings using pole masses more efficient, an approach that we hope will
generalise beyond one loop. We give examples of the impact of different scheme
choices in a toy model; we also discuss the MSSM and give the threshold
corrections to the Higgs quartic coupling in Dirac gaugino models.Comment: 59 pages, 7 figures. v2: added some explanations. Matches published
versio
Leading two-loop corrections to the Higgs boson masses in SUSY models with Dirac gauginos
We compute the two-loop O(as*at) corrections to the Higgs boson masses in
supersymmetric extensions of the Standard Model with Dirac gaugino masses. We
rely on the effective-potential technique, allow for both Dirac and Majorana
mass terms for the gluinos, and compute the corrections in both the DRbar and
on-shell renormalisation schemes. We give detailed results for the MDGSSM and
the MRSSM, and simple approximate formulae valid in the decoupling limit for
all currently-studied variants of supersymmetric models with Dirac gluinos.
These results represent the first explicit two-loop calculation of Higgs boson
masses in supersymmetric models beyond the MSSM and the NMSSM.Comment: 36 pages, 5 figures; v2: version published in JHE
Improved determination of the Higgs mass in the MSSM with heavy superpartners
We present several advances in the effective field theory calculation of the
Higgs mass in MSSM scenarios with heavy superparticles. In particular, we
compute the dominant two-loop threshold corrections to the quartic Higgs
coupling for generic values of the relevant SUSY-breaking parameters, including
all contributions controlled by the strong gauge coupling and by the
third-family Yukawa couplings. We also study the effects of a representative
subset of dimension-six operators in the effective theory valid below the SUSY
scale. Our results will allow for an improved determination of the Higgs mass
and of the associated theoretical uncertainty.Comment: 33 pages, 7 PDF figure
A Fake Split Supersymmetry Model for the 126 GeV Higgs
We consider a scenario where supersymmetry is broken at a high energy scale,
out of reach of the LHC, but leaves a few fermionic states at the TeV scale.
The particle content of the low-energy effective theory is similar to that of
Split Supersymmetry. However, the gauginos and higgsinos are replaced by
fermions carrying the same quantum numbers but having different couplings,
which we call fake gauginos and fake higgsinos. We study the prediction for the
light-Higgs mass in this Fake Split SUSY Model (FSSM). We find that, in
contrast to Split or high-scale supersymmetry, a 126 GeV Higgs boson is easily
obtained even for arbitrarily high values of the supersymmetry scale. For a
supersymmetry scale greater than roughly 100 PeV, the Higgs mass is almost
independent of the supersymmetry scale and the stop mixing parameter, while the
observed value is achieved for tan beta between 1.3 and 1.8 depending on the
gluino mass.Comment: 23 pages, 4 figures; v2: matches published versio
Higgs Mass and Unnatural Supersymmetry
Assuming that supersymmetry exists well above the weak scale, we derive the
full one-loop matching conditions between the SM and the supersymmetric theory,
allowing for the possibility of an intermediate Split-SUSY scale. We also
compute two-loop QCD corrections to the matching condition of the Higgs quartic
coupling. These results are used to improve the calculation of the Higgs mass
in models with high-scale supersymmetry or split supersymmetry, reducing the
theoretical uncertainty. We explore the phenomenology of a mini-split scenario
with gaugino masses determined by anomaly mediation. Depending on the value of
the higgsino mass, the theory predicts a variety of novel possibilities for the
dark-matter particle.Comment: 36 pages, 13 pdf figures; v2: matches version published in JHE
Higgs mass predictions of public NMSSM spectrum generators
The publicly available spectrum generators for the NMSSM often lead to
different predictions for the mass of the standard model-like Higgs boson even
if using the same renormalization scheme and two-loop accuracy. Depending on
the parameter point, the differences can exceed 5 GeV, and even reach 8 GeV for
moderate superparticle masses of up to 2 TeV. It is shown here that these
differences can be traced back to the calculation of the running standard model
parameters entering all calculations, to the approximations used in the
two-loop corrections included in the different codes, and to different choices
for the renormalization conditions and scales. In particular, the importance of
the calculation of the top Yukawa coupling is pointed out.Comment: 24 pages, no figures; v2: slightly extended discussion, matches
version accepted for publication by CP