90 research outputs found
Self-annihilation of the neutralino dark matter into two photons or a Z and a photon in the MSSM
We revisit the one-loop calculation of the annihilation of a pair of the
lightest neutralinos into a pair of photons, a pair of gluons and also a Z
photon final state. For the latter we have identified a new contribution that
may not always be negligible. For all three processes we have conducted a tuned
comparison with previous calculations for some characteristic scenarios. The
approach to the very heavy higgsino and wino is studied and we argue how the
full one-loop calculation should be matched into a more complete treatment that
was presented recently for these extreme regimes. We also give a short
description of the code that we exploited for the automatic calculation of
one-loop cross sections in the MSSM that could apply both for observables at
the colliders and for astrophysics or relic density calculations. In particular
the automatic treatment of zero Gram determinants which appear in the latter
applications is outlined. We also point out how generalised non-linear gauge
fixing constraints can be exploited.Comment: 20 pages, 5 figure
Decoupling Properties of MSSM particles in Higgs and Top Decays
We study the supersymmetric (SUSY) QCD radiative corrections, at the one-loop
level, to , and t quark decays, in the context of the Minimal
Supersymmetric Standard Model (MSSM) and in the decoupling limit. The
decoupling behaviour of the various MSSM sectors is analyzed in some special
cases, where some or all of the SUSY mass parameters become large as compared
to the electroweak scale. We show that in the decoupling limit of both large
SUSY mass parameters and large CP-odd Higgs mass, the decay width approaches its Standard Model value at one loop, with the onset
of decoupling being delayed for large values. However, this
decoupling does not occur if just the SUSY mass parameters are taken large. A
similar interesting non-decoupling behaviour, also enhanced by , is
found in the SUSY-QCD corrections to the decay width
at one loop. In contrast, the SUSY-QCD corrections in the
decay width do decouple and this decoupling is fast.Comment: 19 pages, 10 figures. Invited talk presented by M.J.Herrero at the
5th International Symposium on Radiative Corrections (RADCOR 2000) Carmel CA,
USA, 11-15 September, 200
Large 2HDM(II) one-loop corrections in leptonic tau decays
The one-loop contributions to the branching ratios for leptonic tau decays
are calculated in the CP conserving 2HDM(II). We found that these one-loop
contributions, involving both neutral and charged Higgs bosons, dominate over
the tree-level H^+ exchange, the latter one being totally negligible for the
decay into electron. The analysis is focused on large tanbeta enhanced
contributions to the considered branching ratios. We derive a simple analytical
expression for the one-loop contribution which holds in this case. We show that
the leptonic branching ratios of tau are complementary to the Higgsstrahlung
processes for h(H) and have a large potential on constraining parameters of the
model. In this work we provide upper limits on Yukawa couplings for both light
h and light A scenarios and we derive new lower limit on mass of M_{H^+} as a
function of tanbeta, which differs significantly from what was considered as
standard constraint based on the tree-level H^{+} exchange only. Interestingly
we obtain also an upper limit on M_{H^+}. For a SM-like h scenario, with heavy
and degenerate additional Higgs bosons, one-loop corrections disappear.Comment: 25 pgs. Figures and their descriptions improved, references adde
Flavour physics at large tan(beta) with a Bino-like LSP
The MSSM with large tan(beta) and heavy squarks is a theoretically well
motivated and phenomenologically interesting extension of the SM. This scenario
naturally accommodates the (g-2)_\mu anomaly and the upper bound on the Higgs
boson mass. In a wide region of the parameter space, visible non-standard
effects are expected in a few low-energy observables, such as BR(B->tau nu),
BR(B->l+ l-), BR(B->Xs gamma), and BR(mu->e gamma). We analyse the correlations
of these non-standard effects under the additional assumption that the relic
density of a Bino-like LSP accommodates the observed dark matter distribution.Comment: 19 pages, 7 figures; v2: published version (minor modifications
Flavour Changing Neutral Higgs Boson Decays from Squark - Gluino Loops
We study the flavour changing neutral Higgs boson decays that can be induced
from genuine supersymmetric particles at the one-loop level and within the
context of the Minimal Supersymmetric Standard Model. We consider all the
possible flavour changing decay channels of the three neutral Higgs bosons into
second and third generation quarks, and focus on the Supersymmetric-QCD
corrections from squark-gluino loops which are expected to provide the dominant
contributions. We assume here the more general hypothesis for flavour mixing,
where there is misalignment between the quark and squark sectors, leading to a
flavour non-diagonal squark mass matrix. The form factors involved, and the
corresponding Higgs partial decay widths and branching ratios, are computed
both analytically and numerically, and their behaviour with the parameters of
the Minimal Supersymmetric Standard Model and with the squark mass mixing are
analyzed in full detail. The large rates found, are explained in terms of the
non-decoupling behaviour of these squark-gluino loop corrections in the
scenario with very large supersymmetric mass parameters. Our results show that
if these decays are seen in future colliders they could provide clear indirect
signals of supersymmetry.Comment: 32 Pages and 12 PostScript Level 2 Figures. Some references adde
Effective Higgs-quark-quark couplings from a heavy SUSY spectrum
In this paper we study the Yukawa Higgs-quark-quark interactions that are
generated from radiative corrections of squarks and gluinos, in the Minimal
Supersymmetric Standard Model. We compute the corrections to the effective
action for Higgs and quark fields that are produced by explicit integration, in
the path integral formalism, of all the squarks and gluinos, at the one-loop
level and order . In addition, we consider the limit of nearly
degenerate heavy squarks and gluinos, with masses much larger than the
electroweak scale, and derive the effective Lagrangian containing all the
relevant new local Higgs-quark-quark interactions. We show that these new
interactions do remain non-vanishing, even in the case of infinitely heavy
supersymmetric particles and, therefore, we demonstrate explicitly the
non-decoupling behavior of squarks and gluinos in Higgs bosons physics. We
present the set of new Yukawa couplings and finally derive the corresponding
one-loop, order , corrections to the Higgs bosons partial decay
widths into quarks.Comment: 21 pages, 1 ps figure. Version to appear in Phys. Rev,
SUSY-QCD corrections to the MSSM vertex in the decoupling limit
We analyze the supersymmetric (SUSY) QCD contribution to the
coupling at one loop in the Minimal Supersymmetric Model (MSSM) in the
decoupling limit. Analytic expressions in the large SUSY mass region are
derived and the decoupling behavior of the corrections is examined in various
limiting cases, where some or all of the SUSY mass parameters become large. We
show that in the decoupling limit of large SUSY mass parameters and large
CP-odd Higgs mass, the coupling approaches its Standard Model
value at one loop. However, the onset of decoupling is delayed when
is large. In addition, the one-loop SUSY-QCD corrections decouple if the masses
of either the bottom squarks or the gluino are separately taken large; although
the approach to decoupling is significantly slower in the latter case.Comment: 27 pages, 7 figures and 1 table in LaTeX2e format; with a few minor
changes and updated reference
Author Correction: Pan-cancer analysis of whole genomes identifies driver rearrangements promoted by LINE-1 retrotransposition
Correction to: Nature Genetics https://doi.org/10.1038/s41588-019-0562-0, published online 05 February 2020
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