Search

We describe a method for finding flux vacua of type IIB string theory in which the Gukov-Vafa-Witten superpotential is exponentially small. We present an example with $W_0 \approx 2 \times 10^{-8}$ on an orientifold of a Calabi-Yau hypersurface with $(h^{1,1},h^{2,1})=(2,272)$, at large complex structure and weak string coupling., 5 pages, 1 figure. v2: refs added, minor corrections, results unchanged

We study two cases of interrelations between the enhancement of symmetries in the infrared (IR) and duality properties of supersymmetric quantum field theories in four dimensions. First, we discuss an SU(2) N=1 model with four flavors, singlet fields, and a superpotential. We show that this model flows to a conformal field theory with E6×U(1) global symmetry. The enhancement of the flavor symmetry follows from Seiberg duality. The second example is concerned with an SU(4) gauge theory with matter in the fundamental and antisymmetric representations. We argue that this model has enhanced SO(12) symmetry in the IR, and, guided by this enhancement, we deduce a new IR duality.

We present a new paradigm for supersymmetric theories with R-parity violation (RPV). At high scale, R-parity is conserved in the visible sector but spontaneously broken in the SUSY-breaking sector. The breaking is then dynamically mediated to the visible sector and is manifested via non-renormalizable operators at low energy. Consequently, RPV operators originate from the Kahler potential rather than the superpotential, and are naturally suppressed by the SUSY-breaking scale, explaining their small magnitudes. A new set of non-holomorphic RPV operators are identified and found to often dominate over the standard RPV ones. We study the relevant low-energy constraints arising from baryon-number violating processes, proton decay and flavor changing neutral currents, which may all be satisfied if a solution to the Standard Model flavor puzzle is incorporated. The chiral structure of the RPV operators imply new and distinct collider signatures, indicating the need to alter current techniques in searching for RPV at the LHC., 6 pages, 3 figures

In the standard model the proton is protected from decay naturally by gauge symmetries, whereas in the ordinary minimal supersymmetric standard model an ad hoc discrete symmetry is imposed for the proton stability. We present a new supersymmetric model in which the proton decay is forbidden by an extra U(1) gauge symmetry. Particle contents are necessarily increased to be free from anomalies, incorporating right-handed neutrinos. Both Dirac and Majorana masses are generated for neutrinos, yielding nonvanishing but small masses. The superpotential consists only of trilinear couplings and the mass parameter $\ensuremath{\mu}$ of the minimal model is induced by spontaneous breaking of the U(1) symmetry.

A perturbative non-renormalization theorem is presented that applies to general supersymmetric theories, including non-renormalizable theories in which the $\int d^2\theta$ integrand is an arbitrary gauge-invariant function $F(\Phi,W)$ of the chiral superfields $\Phi$ and gauge field-strength superfields $W$, and the $\int d^4\theta$-integrand is restricted only by gauge invariance. In the Wilsonian Lagrangian, $F(\Phi,W)$ is unrenormalized except for the one-loop renormalization of the gauge coupling parameter, and Fayet-Iliopoulos terms can be renormalized only by one-loop graphs, which cancel if the sum of the U(1) charges of the chiral superfields vanishes. One consequence of this theorem is that in non-renormalizable as well as renormalizable theories, in the absence of Fayet-Iliopoulos terms supersymmetry will be unbroken to all orders if the bare superpotential has a stationary point., Comment: 13 pages (including title page), no figures. Vanilla LaTeX

We give necessary criteria for $N\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ supersymmetric theories to be in a smoothly confining phase without chiral symmetry breaking and with a dynamically generated superpotential. Using our general arguments we find all such confining SU and Sp theories with a single gauge group and no tree-level superpotential.

In supersymmetric quantum mechanics, shape invariance is a sufficient condition for solvability. We show that all conventional additive shape-invariant superpotentials that are independent of $\ensuremath{\hbar}$ can be generated from two partial differential equations. One of these is equivalent to the one-dimensional Euler equation expressing momentum conservation for inviscid fluid flow, and it is closed by the other. We solve these equations, generate the set of all conventional shape-invariant superpotentials, and show that there are no others in this category. We then develop an algorithm for generating all additive shape-invariant superpotentials including those that depend on $\ensuremath{\hbar}$ explicitly.

In D3-brane inflation, the inflaton potential receives important contributions from sources in the compact space, such as fluxes, other D-branes, and orientifold planes. Most previous analyses have considered only the effects of sources near to the inflationary D3-brane, but in fact distant sources do not generically decouple and can critically influence the dynamics during inflation. We provide a systematic method for incorporating the effects of arbitrary distant sources as perturbations to the local supergravity background. We use this approach to obtain the structure of the potential for a D3-brane in a warped throat geometry attached to a general compact space. A significant, and well-known, contribution to this potential arises from quantum effects involved in the stabilization of the compactification volume. Our method automatically captures these effects, encoding them in a suitable flux background.

We analyze non-perturbative corrections to the superpotential of seven-brane gauge theories on type IIB and F-theory warped Calabi-Yau compactifications. We show in particular that such corrections modify the holomorphic Yukawa couplings by an exponentially suppressed contribution, generically solving the Yukawa rank-one problem present in F-theory local models. We provide explicit expressions for the non-perturbative correction to the seven-brane superpotential, and check that it is related to a non-commutative deformation to the tree-level superpotential via the Seiberg-Witten map., 4 pages. v2: minor changes, footnotes and citations added. Version to be published in PRL

We construct the first globally consistent semi-realistic Type I string vacua on an elliptically fibered manifold where the zero modes of the Euclidean D1-instanton sector allow for the generation of non-perturbative Majorana masses of an intermediate scale. In another class of global models, a D1-brane instanton can generate a Polonyi-type superpotential breaking supersymmetry at an exponentially suppressed scale., Comment: 4 pages, 4 tables, uses revtex; v2: Discussion of instanton curves improved, typos fixed, references added; v3: version published in PRL

We show that all domain-wall solutions of gravity coupled to scalar fields for which the worldvolume geometry is Minkowski or anti-de Sitter admit Killing spinors, and satisfy corresponding first-order equations involving a superpotential determined by the solution. By analytic continuation, all flat or closed FLRW cosmologies are shown to satisfy similar first-order equations arising from the existence of ``pseudo-Killing'' spinors., Comment: 4 pages, v2:minor improvements, refs added, version to appear in PRL

Successful leptogenesis within the simplest type I supersymmetric seesaw mechanism requires the lightest of the three right-handed neutrino supermultiplets to be heavier than $\sim10^9$ GeV. Thermal production of such (s)neutrinos requires very high reheating temperatures which result in an overproduction of gravitinos with catastrophic consequences for the evolution of the universe. In this letter, we let R-parity be violated through a $\lambda_i \hat{N}_i \hat{H}_u \hat{H}_d$ term in the superpotential, where $\hat{N}_i$ are right-handed neutrino supermultiplets. We show that in the presence of this term, the produced lepton-antilepton asymmetry can be enhanced. As a result, even for $\hat{N}_1$ masses as low as $10^6$ GeV or less, we can obtain the observed baryon asymmetry of the universe without gravitino overproduction., Comment: 4 pages, 1 figure; v2: minor changes, references added

The fact that neutrinos are massive suggests that the minimal supersymmetric standard model (MSSM) might be extended in order to include three gauge-singlet neutrino superfields with Yukawa couplings of the type $H_2 L \nu^c$. We propose to use these superfields to solve the $\mu$ problem of the MSSM without having to introduce an extra singlet superfield as in the case of the next-to-MSSM (NMSSM). In particular, terms of the type $\nu^c H_1 H_2$ in the superpotential may carry out this task spontaneously through sneutrino vacuum expectation values. In addition, terms of the type $(\nu^c)^3$ avoid the presence of axions and generate effective Majorana masses for neutrinos at the electroweak scale. On the other hand, these terms break lepton number and R-parity explicitly implying that the phenomenology of this model is very different from the one of the MSSM or NMSSM. For example, the usual neutralinos are now mixed with the neutrinos. For Dirac masses of the latter of order $10^{-4}$ GeV, eigenvalues reproducing the correct scale of neutrino masses are obtained., Comment: 9 pages, latex, title modified. Final version published in PRL

Standard D-term inflation is studied in the framework of supergravity. D-term inflation produces cosmic strings, however it can still be compatible with CMB measurements without invoking any new physics. The cosmic strings contribution to the CMB data is not constant, nor dominant, contrary to some previous results. Using current CMB measurements, the free parameters (gauge and superpotential couplings, as well as the Fayet-Iliopoulos term) of D-term inflation are constrained., Comment: 1 Latex file and 3 figures. accepted for publication in Physical Review Letters

Supersymmetric grand unified models based on $\mathrm{SO}(10)$ gauge symmetry have many desirable features, including the unification of Yukawa couplings. Including $D$-term contributions to scalar masses arising from the breakdown of $\mathrm{SO}(10)$, Yukawa coupling unification only to $30%$ can be achieved in models with a positive superpotential Higgs mass. The superparticle mass spectrum is highly constrained and yields relatively light top squarks and charginos. Surprisingly, the pattern of grand unified theory scale soft supersymmetry breaking masses are close to those found in the context of inverted hierarchy models.

We demonstrate that supergravity models containing the standard model, dilaton, and modulus naturally lead to dynamical symmetry breaking with good phenomenology. We assume primordial supersymmetry breaking in the form of a constant contribution to the superpotential. String inspired relations link fundamental couplings to the dilaton vacuum expectation value. We specialize to a class of models inspired by the 4D fermionic string. Nonrenormalizable terms in the superpotential naturally produce the Higgs mixing parameter {mu} suitable for our mechanism. We discuss extensions and limitations of our approach. {copyright} {ital 1996 The American Physical Society.}

We propose a mechanism by which density perturbations δρ/ρ-10 -4 and a baryon asymmetry n B /s ∼10 -10 can naturally be generated in any realistic supersymmetric theory. By «naturally» we mean that the coefficient λ in the usual toy-model inflationary potential V=λO 4 is related to the superpotential Yukama coupling λ e which generates the electron mass. We identify a nine-parameter «quasiflat» direction which generates δρ/ρ through chaotic inflation and which leads to an AflReck-Dine valley (flat direction) where primordial baryogenesis occurs

Based on the target-space modular invariance of the nonperturbative superpotential of the four-dimensional {ital N}=1 supersymmetric string vacua, we find topologically stable, stringy domain walls of nontrivial compactification modulus field configurations. They are supersymmetric solutions, thus saturating the Bogomolnyi bound. Their physical implications are discussed.

It is shown that instantons generate a superpotential in supersymmetric QCD with $N$ colors and $N\ensuremath{-}1$ flavors.

The supersymmetric contributions to the K/sub L/-K/sub S/ mass difference makes the previously obtained bounds on the right-handed scale (M/sub R/>1.6 TeV) much weaker. This raises the interesting possibility that the left-right model could be tested as an alternative to SU/sub L/(2)xU(1) at low energies. Also we find that to demand that the supersymmetric contribution to the K/sub L/-K/sub S/ mass difference be less than 3.5 x 10/sup -15/ GeV requires that scalar-quark masses be more than 400 GeV.

We analyze the simplest discrete symmetries of the superpotential of superstring-inspired E/sub 6/ models necessary to simultaneously suppress (i) proton decay, (ii) neutrino masses, and (iii) tree-level flavor-changing neutral currents in E/sub 6/ superstring models without any intermediate scale. We show that there are two and only two different Z/sub 2/ symmetries that incorporate (i)--(iii). These symmetries put restrictions on the decays of exotic particles; in particular, the exotic quarks always decay semileptonically. A Z/sub 3/-symmetric model satisfying (i)--(iii) and with ..mu -->..e..gamma.. forbidden is also constructed.

The component formulation of the Wess-Zumino superspace action leads, when compared with the general results of Cremmer et al., to a nonminimal version of N = 1 supergravity. A new superpotential, g/sub 2/(z), has been found that gives a scalar potential V(z) that is even in z and which breaks supersymmetry inside the circle of radius ..sqrt..6 /kappa in the complex plane.

We show that all the nonrenormalizable terms in the effective superpotential for any Abelian symmetric orbifold with at least (0,2) world-sheet supersymmetry as well as any blown-up (2,2) orbifold are exponentially suppressed by the size R of the compactified space, i.e., proportionalexp(-R/sup 2//..cap alpha..').

We compute one-loop radiative corrections, including contributions from virtual gravitons and gravitinos, to the scalar potential in $N=1$ supergravity with an arbitrary superpotential. We show that, in a large class of locally supersymmetric grand unified theories, these corrections do not upset the tree-level gauge hierarchy.

Supersymmetric quantum mechanics is formulated for spherically symmetric potentials in N spatial dimensions. It is seen that the supersymmetric partner potential of a given potential can be effectively treated as being in N+2 dimensions. This fact is exploited in calculations using the shifted 1/N expansion. Also, the violation of the no-degeneracy theorem in one dimension by the Coulomb potential is seen as a consequence of this result.