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## Quebra de supersimetria em 2+1-dimensões; Supersymmetry breaking in 2 +1- dimensions

Fonte: Biblioteca Digitais de Teses e Dissertações da USP
Publicador: Biblioteca Digitais de Teses e Dissertações da USP

Tipo: Dissertação de Mestrado
Formato: application/pdf

Publicado em 16/04/2012
PT

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#Quantum Field Theory#Relativistic Quantum Theory#Supersimetria#Supersymmetry#Teoria Quântica de Campo#Teoria Quântica Relativística

Nesse trabalho discutimos alguns aspectos da teoria quântica de campos que nos levam a formulação do potencial efetivo em teorias supersimétricas. O enfoque é dado as técnicas para análise da quebra de supersimetria em 2 + 1-dimensões. São discutidas as condições sobre o potencial efetivo de teorias supersimetrias para que ocorra ou não quebra de supersimetria. O potencial efetivo do modelo Wess-Zumino em 2+1-dimensões é calculado até a aproximação de 2-laços no formalismo de componentes e supercampos e até essa ordem não foi encontrado quebra de supersimetria.; In this work we discuss some aspects of quantum theory of fields used for the formulation of the effective potential of supersymmetric theories. The main focus is given to the methods used to analyse supersimmetry breaking in 2 + 1-dimensions. We discuss the conditions on the effective potential of supersymmetric theories for the occurrence of supersymmetry breaking. The effective potential of Wess-Zumino model em 2 + 1-dimensions is calculated up to 2-loops approximation where supersymmetry breaking is not found to this order.

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## Supersymmetry breaking effects using the pure spinor formalism of the superstring

Fonte: Springer
Publicador: Springer

Tipo: Artigo de Revista Científica
Formato: 19

ENG

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Processo FAPESP: 09/50639-2; Processo FAPESP: 11/11973-4; The SO(32) heterotic superstring on a Calabi-Yau manifold can spontaneously break supersymmetry at one-loop order even when it is unbroken at tree-level. It is known that calculating the supersymmetry-breaking effects in this model gives a relatively accessible test case of the subtleties of superstring perturbation theory in the RNS formalism. In the present paper, we calculate the relevant amplitudes in the pure spinor approach to superstring perturbation theory, and show that the regulator used in computing loop amplitudes in the pure spinor formalism leads to subtleties somewhat analogous to the more familiar subtleties of the RNS approach.

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## Linking natural supersymmetry to flavour physics

Fonte: Springer
Publicador: Springer

Tipo: Artigo de Revista Científica
Formato: 34

ENG

Relevância na Pesquisa

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); With the aim of linking natural supersymmetry to flavour physics, a model is proposed based on a family symmetry G x U(1), where G is a discrete nonabelian subgroup of SU(2), with both F-term and (abelian) D-term supersymmetry breaking. A good fit to the fermion masses and mixing is obtained with the same U(1) charges for the left- and right- handed quarks of the first two families and the right-handed bottom quark, and with zero charge for the left-handed top-bottom doublet and the the right handed top. The model shows an interesting indirect correlation between the correct prediction for the V-ub/V-cb ratio and large right-handed rotations in the (s, b) sector, required to diagonalise the Yukawa matrix. For the squarks, one obtains almost degenerate first two generations. The main source of the FCNC and CP violation effects is the splitting between the first two families and the right-handed sbottom determined by the relative size of F-term and D-term supersymmetry breaking. The presence of the large right-handed rotation implies that the bounds on the masses of the first two families of squarks and the right handed sbottom are in a few to a few tens TeV range. The picture that emerges is light stops and left handed sbottom and much heavier other squarks.

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## Linking natural supersymmetry to flavour physics

Fonte: Springer
Publicador: Springer

Tipo: Artigo de Revista Científica
Formato: 34

ENG

Relevância na Pesquisa

56.45%

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); With the aim of linking natural supersymmetry to flavour physics, a model is proposed based on a family symmetry G xU(1), where G is a discrete nonabelian subgroup of SU(2), with both F-term and (abelian) D-term supersymmetry breaking. A good fit to the fermion masses and mixing is obtained with the same U(1) charges for the left- and right-handed quarks of the first two families and the right-handed bottom quark, and with zero charge for the left- handed top-bottom doublet and the the right handed top. The model shows an interesting indirect correlation between the correct prediction for the V-ub/V-cb ratio and large right-handed rotations in the (s,b) sector, required to diagonalise the Yukawa matrix. For the squarks, one obtains almost degenerate first two generations. The main source of the FCNC and CP violation effects is the splitting between the first two families and the right-handed sbottom determined by the relative size of F-term and D-term supersymmetry breaking. The presence of the large right-handed rotation implies that the bounds on the masses of the first two families of squarks and the right handed sbottom are in a few to a few tens TeV range. The picture that emerges is light stops and left handed sbottom and much heavier other squarks.

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## Duality in the Presence of Supersymmetry Breaking

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

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We study Seiberg duality for N=1 supersymmetric QCD with soft
supersymmetry-breaking terms. We generate the soft terms through gauge
mediation by coupling two theories related by Seiberg duality to the same
supersymmetry-breaking sector. In this way, we know what a
supersymmetry-breaking perturbation in one theory maps into in its ``dual''.
Assuming a canonical Kahler potential we calculate the soft terms induced in
the magnetic theory and find that some of the scalars acquire negative masses
squared. If duality is still good for small supersymmetry breaking, this may
imply some specific symmetry breaking patterns for supersymmetric QCD with
small soft supersymmetry-breaking masses, in the case that its dual theory is
weakly coupled in the infrared. In the limit of large supersymmetry breaking,
the electric theory becomes ordinary QCD. However, the resulting symmetry
breaking in the magnetic theory is incompatible with that expected for QCD.; Comment: 27 pages, LaTex, minor changes, version to appear in Nucl. Phys. B

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## Vacuum Instability in Low-Energy Supersymmetry Breaking Models

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

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We show that for the simplest models of gauge mediated supersymmetry
breaking, including all existing models, the true vacuum will not preserve QCD
if it communicates supersymmetry breaking to the visible sector. We show that
the desired supersymmetry breaking color preserving vacuum can nonetheless be
stable cosmologically, but only if certain couplings are sufficiently small. We
also present simple modifications to the sector which communicates
supersymmetry breaking in which the true vacuum is acceptable, suggesting
desirable properties to be sought in dynamical models of supersymmetry
breaking.; Comment: 19 pages, latex, one postscript figure, uses epsf.tex. An appendix,
two footnotes and a reference are added. Basic results are unchanged

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## Minimally Fine-Tuned Supersymmetric Standard Models with Intermediate-Scale Supersymmetry Breaking

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

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We construct realistic supersymmetric theories in which the correct scale for
electroweak symmetry breaking is obtained without significant fine-tuning. We
consider two classes of models. In one class supersymmetry breaking is
transmitted to the supersymmetric standard model sector through Dirac gaugino
mass terms generated by a D-term vacuum expectation value of a U(1) gauge
field. In the other class the supersymmetry breaking sector is separated from
the supersymmetric standard model sector in an extra dimension, and the
transmission of supersymmetry breaking occurs through gauge mediation. In both
these theories the Higgs sector contains two Higgs doublets and a singlet, but
unlike the case for the next-to-minimal supersymmetric standard model the
singlet field is not responsible for generating the supersymmetric or
supersymmetry breaking mass for the Higgs doublets. These masses, as well as
the mass for the singlet, are generated through gravitational-strength
interactions. The scale at which the squark and slepton masses are generated is
of order (1-100) TeV, and the generated masses do not respect the unified mass
relations. We find that electroweak symmetry breaking in these theories is
caused by an interplay between the top-stop radiative correction and the
holomorphic supersymmetry breaking mass for the Higgs doublets and that the
fine-tuning can be reduced to the level of 20%. The theories have rich
phenomenology...

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## Spontaneous Scherk-Schwarz supersymmetry breaking and radion stabilization

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 13/02/2004

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In this talk I review the issues of supersymmetry breaking and radion
stabilization in a five dimensional theory compactified on the Z_2 orbifold.
Supersymmetry breaking by Scherk-Schwarz boundary conditions is interpreted as
spontaneous breaking of local supersymmetry by the Hosotani mechanism. The
auxiliary field responsible for spontaneous supersymmetry breaking is inside
the five-dimensional off-shell minimal supergravity multiplet. Different ways
of fixing the supersymmetry breaking order parameter are analyzed. In the
presence of supersymmetry breaking the one-loop effective potential for the
radion has a minimum that fixes its vacuum expectation value. The radion is
stabilized in a metastable Minkowski_4 minimum (versus the AdS_4 vacuum) with a
mass in the meV range making it interesting for future deviations from the
gravitational inverse-square law.; Comment: 9 pages, 1 figure. Based on plenary talks presented at SUSY 2003:
Supersymmetry in the Desert, held at the University of Arizona, Tucson, AZ,
June 5-10, 2003; and at the IPPP Workshop on: String Phenomenology 2003, held
at the University of Durham, U.K., July 29-August 4, 2003

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## Radiative Scherk-Schwarz supersymmetry breaking

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

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We analyze the Scherk-Schwarz (SS) supersymmetry breaking in brane-world five
dimensional theories compactified on the orbifold $S^1/\mathbb{Z}_2$. The SS
breaking parameter is undetermined at the tree-level (no-scale supergravity)
and can be interpreted as the Hosotani vacuum expectation value corresponding
to the $U(1)_R$ group in five dimensional N=2 (ungauged) supergravity. We show
that the SS breaking parameter is fixed at the loop level to either 0 or 1/2
depending on the matter content propagating in the bulk but in a rather
model-independent way. Supersymmetry breaking is therefore fixed through a
radiative Scherk-Schwarz mechanism. We also show that the two discrete values
of the SS parameter, as well as the supersymmetry breaking shift in the
spectrum of the bulk fields, are altered in the presence of a brane-localized
supersymmetry breaking arising from some hidden sector dynamics. The interplay
between the SS and the brane localized breaking is studied in detail.; Comment: 16 pages, 2 figures, uses axodraw. References added

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## Probing the supersymmetry breaking mechanism using renormalisation group invariants

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 06/11/2012

Relevância na Pesquisa

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If supersymmetric particles are discovered, an important problem will be to
determine how supersymmetry has been broken. At collider energies,
supersymmetry breaking can be parameterised by soft supersymmetry breaking
parameters. Several mechanisms for supersymmetry breaking have been proposed,
which are all characterised by patterns in the high scale values of these
parameters. Therefore, looking for such patterns will give us important clues
about the way supersymmetry has been broken in Nature. In this master thesis,
we study an approach to find these patterns using Renormalisation Group
invariants. We construct sum rules that test properties of the spectrum at the
scale of supersymmetry breaking, provided that the Minimal Supersymmetric
Standard Model is a good description of Nature at collider energies and all
soft mass parameters and gauge couplings have been determined. Subsequently, we
examine to what extent these sum rules can distinguish between different
supersymmetry breaking scenarios. It is found that our sum rules provide
unambiguous checks in almost all cases.; Comment: 98 pages, 10 figures. Master thesis completed at the department of
Theoretical High Energy Physics at the Radboud University Nijmegen in August
2011...

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## Implications of different supersymmetry breaking patterns for the spectrum and decay of neutralinos and charginos

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

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We consider different patterns of supersymmetry breaking gaugino masses, and
implications of these patterns for the phenomenology of neutralinos and
charginos in models of low energy supersymmetry. We outline a general procedure
for obtaining approximate values for the neutralino masses relevant for our
analysis, and describe the constraints on the gaugino mass parameters which
follow from the present experimental limits on the mass of the lightest
chargino. We evaluate an upper bound on the mass of the lightest neutralino
that follows from the structure of the mass matrix in different models for the
gaugino mass parameters. Using the experimental lower limit for the chargino
mass, we examine the lower bound for the neutralino masses. Using a sum rule
for the squared masses of charginos and neutralinos, we discuss how to
distinguish between different models for the supersymmetry breaking scenarios.
We discuss in detail the decay modes of neutralinos and charginos in different
models of supersymmetry breaking. Our analysis shows that by measuring the
masses and decay properties of the neutralinos, one can distinguish between
different patterns of supersymmetry breaking in the gaugino sector. We then
compare the dark matter characteristics that arise in different models of
supersymmetry breaking.; Comment: 21 pages...

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## Supersymmetry Breaking by Higher Dimension Operators

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 05/09/2013

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We discuss a supersymmetry breaking mechanism for N = 1 theories triggered by
higher dimensional op- erators. We consider such operators for real linear and
chiral spinor superfields that break superymmetry and reduce to the
Volkov-Akulov action. We also consider supersymmetry breaking induced by a
higher dimensional operator of a nonminimal scalar (complex linear) multiplet.
The latter differs from the stan- dard chiral multiplet in its auxiliary
sector, which contains, in addition to the complex scalar auxiliary of a chiral
superfield, a complex vector and two spinors auxiliaries. By adding an
appropriate higher di- mension operator, the scalar auxiliary may acquire a
nonzero vev triggering spontaneous supersymmetry breaking. We find that the
spectrum of the theory in the supersymmetry breaking vacuum consists of a free
chiral multiplet and a constraint chiral superfield describing the goldstino.
Interestingly, the latter turns out to be one of the auxiliary fermions, which
becomes dynamical in the supersymmetry breaking vacuum. In all cases we are
considering here, there is no sgoldstino mode and thus the goldstino does not
have a superpartner. The sgoldstino is decoupled since the goldstino is one of
the auxiliaries, which is propagating only in the supersymmetry breaking
vacuum. We also point out how higher dimension operators introduce a potential
for the propagating scalar of the theory.; Comment: 28 pages

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## On the Soft Supersymmetry Breaking Parameters in Gauge-Mediated Models

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 21/01/1998

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Gauge mediation of supersymmetry breaking in the observable sector is an
attractive idea, which naturally alleviates the flavour changing neutral
current problem of supersymmetric theories. Quite generally, however, the
number and quantum number of the messengers are not known; nor is their
characteristic mass scale determined by the theory. Using the recently proposed
method to extract supersymmetry-breaking parameters from wave-function
renormalization, we derived general formulae for the soft
supersymmetry-breaking parameters in the observable sector, valid in the small
and moderate $\tan\beta$ regimes, for the case of split messengers. The full
leading-order effects of top Yukawa and gauge couplings on the soft
supersymmetry-breaking parameters are included. We give a simple interpretation
of the general formulae in terms of the renormalization group evolution of the
soft supersymmetry-breaking parameters. As a by-product of this analysis, the
one-loop renormalization group evolution of the soft supersymmetry breaking
parameters is obtained for arbitrary boundary conditions of the scalar and
gaugino mass parameters at high energies.; Comment: 17 pages, LateX

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## New Models of Gauge and Gravity Mediated Supersymmetry Breaking

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

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We show that supersymmetry breaking in a class of theories with SU(N) x
SU(N-2) gauge symmetry can be studied in a calculable sigma model. We use the
sigma model to show that the supersymmetry breaking vacuum in these theories
leaves a large subgroup of flavor symmetries intact, and to calculate the
masses of the low-lying states. By embedding the Standard Model gauge groups in
the unbroken flavor symmetry group we construct a class of models in which
supersymmetry breaking is communicated by both gravitational and gauge
interactions. One distinguishing feature of these models is that the messenger
fields, responsible for the gauge mediated communication of supersymmetry
breaking, are an integral part of the supersymmetry breaking sector. We also
show how, by lowering the scale that suppresses the nonrenormalizable
operators, a class of purely gauge mediated models with a combined
supersymmetry breaking-cum-messenger sector can be built. We briefly discuss
the phenomenological features of the models we construct.; Comment: Revised discussion of communication of supersymmetry breaking, 24
pages, LaTeX

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## Effective Messenger Sector from Dynamical Supersymmetry Breaking

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 26/12/1996

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In the framework of the dynamical supersymmetry breaking we construct the
messenger sector as the effective theory of supersymmetry breaking sector,
which is based on SU(3) \times SU(2) model of Affleck, Dine and Seiberg. In our
model, messenger superfields with non-renormalizable interaction are contained.
By minimizing the scalar potential, we show that the supersymmetry breaking can
be communicated to the visible sector without breaking QCD color. In this model
there appear various scales. Supersymmetry breaking scale turns out to be the
intermediate scale ( \sim 10^{10} GeV ) between the GUT scale and the soft
supersymmetry breaking scale.; Comment: 15pages, LaTeX, no figures

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## Mechanisms of Supersymmetry Breaking in the MSSM

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Relevância na Pesquisa

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Preliminary Remarks. Gauge mediated supersymmetry breaking. Gravity mediated
supersymmetry breaking. Anomaly mediated supersymmetry breaking. Gaugino
mediated supersymmetry breaking. Braneworld supersymmetry breaking.
Conclusions.; Comment: New references added, minor misprints corrected, text otherwise
unchanged

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## The scale of supersymmetry breaking as a free parameter

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 15/02/2001

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While supersymmetric extensions of the Standard Model can be fully described
in terms of explicitly broken global supersymmetry, this description is only
effective. Once related to spontaneous breaking in a more fundamental theory,
the effective parameters translate to functions of two distinct scales, the
scale of spontaneous supersymmetry breaking and the scale of its mediation to
the standard-model fields. The scale dependence will be written explicitly and
the full spectrum of supersymmetry breaking operators which emerges will be
explored. It will be shown that, contrary to common lore, scale-dependent
operators can play an important role in determining the phenomenology. For
example, theories with low-energy supersymmetry breaking, such as gauge
mediation, may correspond to a scalar potential which is quite different than
in theories with high-energy supersymmetry breaking, such as gravity mediation.
As a concrete example, the Higgs mass prediction will be discussed in some
detail and its upper bound will be shown to be sensitive to the supersymmetry
breaking scale.; Comment: 9 pages, 1 figure (included). Requires espcrc2.sty (included). Talk
given at the 30 Years of Supersymmetry workshop, Oct. 2000

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## Inflation and the Nature of Supersymmetry Breaking

Fonte: Universidade Cornell
Publicador: Universidade Cornell

Tipo: Artigo de Revista Científica

Publicado em 11/07/1997

Relevância na Pesquisa

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The scale at which supersymmetry is broken and the mechanism by which
supersymmetry breaking is fed down to the observable sector has rich
implications on the way Nature may have chosen to accomplish inflation. We
discuss a simple model for slow rollover inflation which is minimal in the
sense that the inflaton may be identified with the field responsible for the
generation of the $\mu$-term. Inflation takes place at very late times and is
characterized by a very low reheating temperature. This property is crucial to
solve the gravitino problem and may help to ameliorate the cosmological moduli
problem. The COBE normalized value of the vacuum energy driving inflation is
naturally of the order of $10^{11}$ GeV. This favors the N=1 supergravity
scenario where supersymmetry breaking is mediated by gravitational
interactions. Nonetheless, smaller values of the vacuum energy are not excluded
by present data on the temperature anisotropy and the inflationary scenario may
be implemented in the context of new recent ideas about gauge mediation where
the standard model gauge interactions can serve as the messangers of
supersymmetry breaking. In this class of models supersymmetry breaking masses
are usually prop ortional to the F-term of a gauge singlet superfield. The same
F-term may provide the vacuum energy density necessary to drive inflation. The
spectrum of density perturbations is characterized by a spectral index which is
significantly displaced from one. The measurements of the temperature
anisotropies in the cosmic microwave background radiation at the accuracy
expected to result from the planned missions will be able to confirm or
disprove this prediction and to help in getting some deeper insight into the
nature of supersymmetry breaking.; Comment: 25 pages...

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## The Spectrum of the MSSM with nonstandard supersymmetry breaking.

Fonte: HEP, Cavendish Laboratory, University of Cambridge
Publicador: HEP, Cavendish Laboratory, University of Cambridge

Tipo: Article; not applicable

EN

Relevância na Pesquisa

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The Minimal Supersymmetric Standard Model (MSSM) can include two
soft breaking terms which are often neglected: a non-analytic scalar trilinear coupling
and a Higgsino bilinear term. A set of high-scale boundary conditions consistent
with the reparameterisation invariance which the model possesses is obtained. The
three-family renormalisation group equations for the MSSM with these terms are
presented. The ranges of the universal high-scale values of these couplings which lead
to an acceptable TeV-scale theory are obtained, as is the supersymmetric particle
spectrum at this scale. The effect of the new terms on fine-tuning is presented.
SOFTSUSY, an existing program for calculating SUSY particle spectra, has been
used, with as few modifications as possible.

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## Linking natural supersymmetry to flavour physics

Fonte: Springer
Publicador: Springer

Tipo: Artigo de Revista Científica
Formato: 34

ENG

Relevância na Pesquisa

56.45%

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); With the aim of linking natural supersymmetry to flavour physics, a model is proposed based on a family symmetry G xU(1), where G is a discrete nonabelian subgroup of SU(2), with both F-term and (abelian) D-term supersymmetry breaking. A good fit to the fermion masses and mixing is obtained with the same U(1) charges for the left- and right-handed quarks of the first two families and the right-handed bottom quark, and with zero charge for the left- handed top-bottom doublet and the the right handed top. The model shows an interesting indirect correlation between the correct prediction for the V-ub/V-cb ratio and large right-handed rotations in the (s,b) sector, required to diagonalise the Yukawa matrix. For the squarks, one obtains almost degenerate first two generations. The main source of the FCNC and CP violation effects is the splitting between the first two families and the right-handed sbottom determined by the relative size of F-term and D-term supersymmetry breaking. The presence of the large right-handed rotation implies that the bounds on the masses of the first two families of squarks and the right handed sbottom are in a few to a few tens TeV range. The picture that emerges is light stops and left handed sbottom and much heavier other squarks.

Link permanente para citações: