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

Mendonça, Hudson Kazuo Teramoto
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
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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.

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

Berkovits, Nathan; Witten, Edward
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.

## Linking natural supersymmetry to flavour physics

Dudas, Emilian; von Gersdorff, Gero; Pokorski, Stefan; Ziegler, Robert
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.

## Linking natural supersymmetry to flavour physics

Dudas, Emilian; von Gersdorff, Gero; Pokorski, Stefan; Ziegler, Robert
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.

## Duality in the Presence of Supersymmetry Breaking

Tipo: Artigo de Revista Científica
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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

## Vacuum Instability in Low-Energy Supersymmetry Breaking Models

Dasgupta, Indranil; Dobrescu, Bogdan A.; Randall, Lisa
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.58%
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

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

Nomura, Yasunori; Poland, David; Tweedie, Brock
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.61%
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...

## Spontaneous Scherk-Schwarz supersymmetry breaking and radion stabilization

Quiros, M.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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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

Gersdorff, G. v.; Quiros, M.; Riotto, A.
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

## Probing the supersymmetry breaking mechanism using renormalisation group invariants

Hetzel, Jamil
Tipo: Artigo de Revista Científica
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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...

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

Huitu, Katri; Laamanen, Jari; Pandita, P. N.; Tiitola, Paavo
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.6%
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...

## Supersymmetry Breaking by Higher Dimension Operators

Farakos, Fotis; Ferrara, Sergio; Kehagias, Alex; Porrati, Massimo
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.62%
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

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

Wagner, C. E. M.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.62%
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

## New Models of Gauge and Gravity Mediated Supersymmetry Breaking

Poppitz, E.; Trivedi, S. P.
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

## Effective Messenger Sector from Dynamical Supersymmetry Breaking

Haba, Naoyuki; Maru, Nobuhito; Matsuoka, Takeo
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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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

## Mechanisms of Supersymmetry Breaking in the MSSM

Roy, Probir
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

## The scale of supersymmetry breaking as a free parameter

Polonsky, Nir
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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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

## Inflation and the Nature of Supersymmetry Breaking

Riotto, Antonio
Tipo: Artigo de Revista Científica
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...

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

Hetherington, J. P. J.
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.

## Linking natural supersymmetry to flavour physics

Dudas, Emilian; von Gersdorff, Gero; Pokorski, Stefan; Ziegler, Robert