331 research outputs found
The Full Two-Loop R-parity Violating Renormalization Group Equations for All Minimal Supersymmetric Standard Model Couplings
We present the full two-loop -functions for the minimal supersymmetric
standard model couplings, extended to include R-parity violating couplings
through explicit R-parity violation
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Effects of random pinning on the potential energy landscape of a supercooled liquid.
We use energy landscape methods to investigate the response of a supercooled liquid to random pinning. We classify the structural similarity of different energy minima using a measure of overlap. This analysis reveals a correspondence between distinct particle packings (which are characterised via the overlap) and funnels on the energy landscape (which are characterised via disconnectivity graphs). As the number of pinned particles is increased, we find a crossover from glassy behavior at low pinning to a structure-seeking landscape at high pinning, in which all thermally accessible minima are structurally similar. We discuss the consequences of these results for theories of randomly pinned liquids. We also investigate how the energy landscape depends on the fraction of pinned particles, including the degree of frustration and the evolution of distinct packings as the number of pinned particles is reduced.epsr
Light MSSM Higgs boson mass to three-loop accuracy
The light CP even Higgs boson mass, Mh, is calculated to three-loop accuracy
within the Minimal Supersymmetric Standard Model (MSSM). The result is
expressed in terms of DRbar parameters and implemented in the computer program
H3m. The calculation is based on the proper approximations and their
combination in various regions of the parameter space. The three-loop effects
to Mh are typically of the order of a few hundred MeV and opposite in sign to
the two-loop corrections. The remaining theory uncertainty due to higher order
perturbative corrections is estimated to be less than 1 GeV.Comment: 39 pages, 13 figures. v2: minor changes, typos fixe
Two-loop RGEs with Dirac gaugino masses
The set of renormalisation group equations to two loop order for general
supersymmetric theories broken by soft and supersoft operators is completed. As
an example, the explicit expressions for the RGEs in a Dirac gaugino extension
of the (N)MSSM are presented.Comment: 10 pages + 24 pages of RGEs in appendix; no figure
Combining Anomaly and Z' Mediation of Supersymmetry Breaking
We propose a scenario in which the supersymmetry breaking effect mediated by
an additional U(1)' is comparable with that of anomaly mediation. We argue that
such a scenario can be naturally realized in a large class of models. Combining
anomaly with Z' mediation allows us to solve the tachyonic slepton problem of
the former and avoid significant fine tuning in the latter. We focus on an
NMSSM-like scenario where U(1)' gauge invariance is used to forbid a tree-level
mu term, and present concrete models, which admit successful dynamical
electroweak symmetry breaking. Gaugino masses are somewhat lighter than the
scalar masses, and the third generation squarks are lighter than the first two.
In the specific class of models under consideration, the gluino is light since
it only receives a contribution from 2-loop anomaly mediation, and it decays
dominantly into third generation quarks. Gluino production leads to distinct
LHC signals and prospects of early discovery. In addition, there is a
relatively light Z', with mass in the range of several TeV. Discovering and
studying its properties can reveal important clues about the underlying model.Comment: Minor changes: references added, typos corrected, journal versio
(Extra)Ordinary Gauge/Anomaly Mediation
We study anomaly mediation models with gauge mediation effects from
messengers which have a general renormalizable mass matrix with a
supersymmetry-breaking spurion. Our models lead to a rich structure of
supersymmetry breaking terms in the visible sector. We derive sum rules among
the soft scalar masses for each generation. Our sum rules for the first and
second generations are the same as those in general gauge mediation, but the
sum rule for the third generation is different because of the top Yukawa
coupling. We find the parameter space where the tachyonic slepton problem is
solved. We also explore the case in which gauge mediation causes the
anomalously small gaugino masses. Since anomaly mediation effects on the
gaugino masses exist, we can obtain viable mass spectrum of the visible sector
fields.Comment: 24 pages, 10 figure
When Anomaly Mediation is UV Sensitive
Despite its successes---such as solving the supersymmetric flavor
problem---anomaly mediated supersymmetry breaking is untenable because of its
prediction of tachyonic sleptons. An appealing solution to this problem was
proposed by Pomarol and Rattazzi where a threshold controlled by a light field
deflects the anomaly mediated supersymmetry breaking trajectory, thus evading
tachyonic sleptons. In this paper we examine an alternate class of deflection
models where the non-supersymmetric threshold is accompanied by a heavy,
instead of light, singlet. The low energy form of this model is the so-called
extended anomaly mediation proposed by Nelson and Weiner, but with potential
for a much higher deflection threshold. The existence of this high deflection
threshold implies that the space of anomaly mediated supersymmetry breaking
deflecting models is larger than previously thought.Comment: 14 pages, 1 figure (version to appear in JHEP
LHC and lepton flavour violation phenomenology of a left-right extension of the MSSM
We study the phenomenology of a supersymmetric left-right model, assuming
minimal supergravity boundary conditions. Both left-right and (B-L) symmetries
are broken at an energy scale close to, but significantly below the GUT scale.
Neutrino data is explained via a seesaw mechanism. We calculate the RGEs for
superpotential and soft parameters complete at 2-loop order. At low energies
lepton flavour violation (LFV) and small, but potentially measurable mass
splittings in the charged scalar lepton sector appear, due to the RGE running.
Different from the supersymmetric 'pure seesaw' models, both, LFV and slepton
mass splittings, occur not only in the left- but also in the right slepton
sector. Especially, ratios of LFV slepton decays, such as Br()/Br() are sensitive to the
ratio of (B-L) and left-right symmetry breaking scales. Also the model predicts
a polarization asymmetry of the outgoing positrons in the decay , A ~ [0,1], which differs from the pure seesaw 'prediction' A=1$.
Observation of any of these signals allows to distinguish this model from any
of the three standard, pure (mSugra) seesaw setups.Comment: 43 pages, 17 figure
Precision Gauge Unification from Extra Yukawa Couplings
We investigate the impact of extra vector-like GUT multiplets on the
predicted value of the strong coupling. We find in particular that Yukawa
couplings between such extra multiplets and the MSSM Higgs doublets can resolve
the familiar two-loop discrepancy between the SUSY GUT prediction and the
measured value of alpha_3. Our analysis highlights the advantages of the
holomorphic scheme, where the perturbative running of gauge couplings is
saturated at one loop and further corrections are conveniently described in
terms of wavefunction renormalization factors. If the gauge couplings as well
as the extra Yukawas are of O(1) at the unification scale, the relevant
two-loop correction can be obtained analytically. However, the effect persists
also in the weakly-coupled domain, where possible non-perturbative corrections
at the GUT scale are under better control.Comment: 26 pages, LaTeX. v6: Important early reference adde
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