Supersymmetry breaking Research Papers - Academia.edu (original) (raw)
We revisit the analysis of effective field theories resulting from non-supersymmetric perturbations to supersymmetric flux compactifications of the type-IIB superstring with an eye towards those resulting from the backreaction of a small... more
We revisit the analysis of effective field theories resulting from non-supersymmetric perturbations to supersymmetric flux compactifications of the type-IIB superstring with an eye towards those resulting from the backreaction of a small number of D3-branes. Independently of the background, we show that the low-energy Lagrangian describing the fluctuations of a stack of probe D3-branes exhibits soft supersymmetry breaking, despite perturbations to marginal operators that were not fully considered in some previous treatments. We take this as an indication that the breaking of supersymmetry by D3-branes or other sources may be spontaneous rather than explicit. In support of this, we consider the action of an D3-brane probing an otherwise supersymmetric configuration and identify a candidate for the corresponding goldstino.
We discuss gravitational backgrounds where supersymmetry is broken at the end of a warped throat, and the SUSY-breaking is transmitted to the Standard Model via gauginos which live in (part of) the bulk of the throat geometry. We find... more
We discuss gravitational backgrounds where supersymmetry is broken at the end of a warped throat, and the SUSY-breaking is transmitted to the Standard Model via gauginos which live in (part of) the bulk of the throat geometry. We find that the leading effect arises from splittings of certain "messenger mesons," which are adjoint KK-modes of the D-branes supporting the Standard Model gauge group. This picture is a gravity dual of a strongly coupled field theory where SUSY is broken in a hidden sector and transmitted to the Standard Model via a relative of semi-direct gauge mediation.
. The volume is exponentially large, leading to a range of string scales from the Planck mass to the TeV scale, realising for the first time the large extra dimensions scenario in string theory. We provide a general analysis of the... more
. The volume is exponentially large, leading to a range of string scales from the Planck mass to the TeV scale, realising for the first time the large extra dimensions scenario in string theory. We provide a general analysis of the relevance of perturbative and non-perturbative effects and the regime of validity of the effective field theory. We compute the spectrum in the moduli sector finding a hierarchy of masses depending on inverse powers of the volume. We also compute soft supersymmetry breaking terms for particles living on D3 and D7 branes. We find a hierarchy of soft terms corresponding to `volume dominated' F-term supersymmetry breaking. F-terms for Kahler moduli dominate both those for dilaton and complex structure moduli and D-terms or other de Sitter lifting terms. This is the first class of string models in which soft supersymmetry breaking terms are computed after fixing all geometric moduli. We outline several possible applications of our results, both for cosmology and phenomenology and point out the differences with the less generic KKLT vacua.
Back-reaction effects can modify the dynamics of mobile D3 branes moving within type IIB vacua, in a way which has recently become calculable. We identify some of the ways these effects can alter inflationary scenarios, with the following... more
Back-reaction effects can modify the dynamics of mobile D3 branes moving within type IIB vacua, in a way which has recently become calculable. We identify some of the ways these effects can alter inflationary scenarios, with the following three results: (1) By examining how the forces on the brane due to moduli-stabilizing interactions modify the angular motion of D3 branes moving in Klebanov-Strassler type throats, we show how previous slow-roll analyses can remain unchanged for some brane trajectories, while being modified for other trajectories. These forces cause the D3 brane to sink to the bottom of the throat except in a narrow region close to the D7 brane, and do not ameliorate the \eta-problem of slow roll inflation in these throats; (2) We argue that a recently-proposed back-reaction on the dilaton field can be used to provide an alternative way of uplifting these compactifications to Minkowski or De Sitter vacua, without the need for a supersymmetry-breaking anti-D3 brane; and (3) by including also the D-term forces which arise when supersymmetry-breaking fluxes are included on D7 branes we identify the 4D supergravity interactions which capture the dynamics of D3 motion in D3/D7 inflationary scenarios. The form of these potentials sheds some light on recent discussions of how symmetries constrain D term interactions in the low-energy theory.
We describe the construction of string theory models with semirealistic spectrum in a sector of (anti) D3-branes located at an orbifold singularity at the bottom of a highly warped throat geometry, which is a generalisation of the... more
We describe the construction of string theory models with semirealistic spectrum in a sector of (anti) D3-branes located at an orbifold singularity at the bottom of a highly warped throat geometry, which is a generalisation of the Klebanov-Strassler deformed conifold. These models realise the Randall-Sundrum proposal to naturally generate the Planck/electroweak hierarchy in a concrete string theory embedding, and yielding interesting chiral open string spectra. We describe examples with Standard Model gauge group (or left-right symmetric extensions) and three families of SM fermions, with correct quantum numbers including hypercharge. The dilaton and complex structure moduli of the geometry are stabilised by the 3-form fluxes required to build the throat. We describe diverse issues concerning the stabilisation of geometric Kahler moduli, like blow-up modes of the orbifold singularities, via D term potentials and gauge theory non-perturbative effects, like gaugino condensation. This local geometry, once embedded in a full compactification, could give rise to models with all moduli stabilised, and with the potential to lead to de Sitter vacua. Issues of gauge unification, proton stability, supersymmetry breaking and Yukawa couplings are also discussed.
The cosmological constant problem is turned around to argue for a new foundational physics postulate underlying a consistent quantum theory of gravity and matter, such as string theory. This postulate is a quantum equivalence principle... more
The cosmological constant problem is turned around to argue for a new foundational physics postulate underlying a consistent quantum theory of gravity and matter, such as string theory. This postulate is a quantum equivalence principle which demands a consistent gauging of the geometric structure of canonical quantum theory. We argue that string theory can be formulated to accommodate such a
We study SUSY phenomenology of the KKLT (Kachru-Kallosh-Linde-Trivedi) scenario of string theory compactifications with fluxes. This setup leads to a specific pattern of soft masses and distinct phenomenological properties. In particular,... more
We study SUSY phenomenology of the KKLT (Kachru-Kallosh-Linde-Trivedi) scenario of string theory compactifications with fluxes. This setup leads to a specific pattern of soft masses and distinct phenomenological properties. In particular, it avoids the cosmological gravitino/moduli problems. Remarkably, the model allows for the correct abundance of SUSY dark matter consistently with all experimental constraints including the bound on the Higgs mass, b-->s gamma, etc. This occurs for both small and large tan beta, and requires the SUSY spectrum above 1 TeV.
We study the large volume limit of the scalar potential in Calabi-Yau flux compactifications of type IIB string theory. Under general circumstances there exists a limit in which the potential approaches zero from below, with an associated... more
We study the large volume limit of the scalar potential in Calabi-Yau flux compactifications of type IIB string theory. Under general circumstances there exists a limit in which the potential approaches zero from below, with an associated non-supersymmetric AdS minimum at exponentially large volume. Both this and its de Sitter uplift are tachyon-free, thereby fixing all Kahler and complex structure moduli, which has been difficult to achieve in the KKLT scenario. Also, for the class of vacua described in this paper, the gravitino mass is independent of the flux discretuum, whereas the ratio of the string scale to the 4d Planck scale is hierarchically small but flux dependent. The inclusion of alpha' corrections plays a crucial role in the structure of the potential. We illustrate these ideas through explicit computations for a particular Calabi-Yau manifold.
The Minimal Supersymmetric extension of the Standard Model provides a solution to the hierarchy problem and leads to the presence of a light Higgs. A Higgs boson with mass above the present experimental bound may only be obtained for... more
The Minimal Supersymmetric extension of the Standard Model provides a solution to the hierarchy problem and leads to the presence of a light Higgs. A Higgs boson with mass above the present experimental bound may only be obtained for relatively heavy third generation squarks, requiring a precise, somewhat unnatural balance between different contributions to the effective Higgs mass parameter. It was recently noticed that somewhat heavier Higgs bosons, which are naturally beyond the LEP bound, may be obtained by enhanced weak SU(2) D-terms. Such contributions appear in models with an enhanced electroweak gauge symmetry, provided the supersymmetry breaking masses associated with the scalars responsible for the breakdown of the enhanced gauge symmetry group to the Standard Model one, are larger than the enhanced symmetry breaking scale. In this article we emphasize that the enhanced SU(2) D-terms will not only raise the Higgs boson mass but also affect the spectrum of the non-standard Higgs bosons, sleptons and squarks, which therefore provide a natural contribution to the T parameter, compensating for the negative one coming from the heavy Higgs boson. The sleptons and non-standard Higgs bosons of these models, in particular, may act in a way similar to the so-called inert Higgs doublet. The phenomenological properties of these models are emphasized and possible cosmological implications as well as collider signatures are described.
In this paper I provide a general framework based on deltaN\delta NdeltaN formalism to study the features of unavoidable higher dimensional non-renormalizable K\"ahler operators for calN=1{\cal N}=1calN=1 supergravity (SUGRA) during primordial inflation from... more
In this paper I provide a general framework based on deltaN\delta NdeltaN formalism to study the features of unavoidable higher dimensional non-renormalizable K\"ahler operators for calN=1{\cal N}=1calN=1 supergravity (SUGRA) during primordial inflation from the combined constraint on non-Gaussianity, sound speed and CMB dipolar asymmetry as obtained from the recent Planck data.
In particular I study the nonlinear evolution of cosmological perturbations on large scales which enables us to compute the curvature perturbation, zeta\zetazeta, without solving the exact perturbed field equations. Further I compute the non-Gaussian parameters fNLf_{NL}fNL , tauNL\tau_{NL}tauNL and gNLg_{NL}gNL for local type of non-Gaussianities and CMB dipolar asymmetry parameter, $ A_{CMB}$, using the deltaN\delta NdeltaN formalism for a generic class of sub-Planckian models induced by the Hubble-induced corrections for a minimal supersymmetric D-flat direction where inflation occurs at the point of inflection within the visible sector.
Hence by using multi parameter scan I constrain the non-minimal couplings appearing in non-renormalizable K\"ahler operators within, calO(1){\cal O}(1)calO(1), for the speed of sound, 0.02leqcsleq10.02\leq c_s\leq 10.02leqcsleq1, and tensor to scalar, 10−22leqrstarleq0.1210^{-22} \leq r_{\star} \leq 0.1210−22leqrstarleq0.12. Finally applying all of these constraints I will fix the lower as well as the upper bound of the non-Gaussian parameters within, calO(1−5)leqfNLleq8.5{\cal O}(1-5)\leq f_{NL}\leq 8.5calO(1−5)leqfNLleq8.5, calO(75−150)leqtauNLleq2800{\cal O}(75-150)\leq\tau_{NL}\leq 2800calO(75−150)leqtauNLleq2800 and calO(17.4−34.7)leqgNLleq648.2{\cal O}(17.4-34.7)\leq g_{NL}\leq 648.2calO(17.4−34.7)leqgNLleq648.2, and CMB dipolar asymmetry parameter within the range, 0.05leqACMBleq0.090.05\leq A_{CMB}\leq 0.090.05leqACMBleq0.09.
In this paper we will illustrate how to constrain unavoidable K\"ahler corrections for calN=1{\cal N}=1calN=1 supergravity (SUGRA) inflation from the recent Planck data. We will show that non-renormalizable K\"ahler operators will induce in... more
In this paper we will illustrate how to constrain unavoidable K\"ahler corrections for calN=1{\cal N}=1calN=1 supergravity (SUGRA)
inflation from the recent Planck data. We will show that non-renormalizable K\"ahler operators will induce in general {\it non-minimal kinetic} term for the inflaton field,
and two types of SUGRA corrections in the potential - the {\it Hubble-induced mass} ($c_{H}$), and the {\it Hubble-induced A-term} ($a_{H}$) correction.
The entire SUGRA inflationary framework can now be constrained from (i) {\it speed of sound}, csc_scs, and (ii) from the upper bound on the {\it tensor to scalar ratio}, rstarr_{\star}rstar.
We will illustrate this by considering a heavy scalar degree of freedom at a scale, MsM_sMs, and a light inflationary field which is responsible for a slow-roll inflation. We will compute
the corrections to the kinetic term and the potential explicitly. As an example we will consider a visible sector inflationary model of inflation where inflation occurs at the point
of {\it inflection}, which can match
the density perturbations for the cosmic microwave background radiation, and also explain why the universe is filled with the Standard Model degrees of freedom.
We will scan the parameter space of non-renormalizable K\"ahler operators, which we find them to be order calO(1){\cal O}(1)calO(1), as expected from physical arguments.
While the scale of heavy physics is found to be bounded by the tensor-to scalar ratio and the speed of sound, this high
scale comes out to be varying within a range, $ {\cal O}(10^{11}\leq M_s\leq 10^{16})$~GeV, for the speed of sound varying from 0.02leqcsleq10.02\leq c_s\leq 10.02leqcsleq1, and tensor to scalar
ratio varying from 10−22leqrstarleq0.1210^{-22} \leq r_{\star} \leq 0.1210−22leqrstarleq0.12.
We propose a new mechanism for obtaining de Sitter vacua in type IIB string theory compactified on (orientifolded) Calabi-Yau manifolds similar to those recently studied by Kachru, Kallosh, Linde and Trivedi (KKLT). dS vacuum appears in... more
We propose a new mechanism for obtaining de Sitter vacua in type IIB string theory compactified on (orientifolded) Calabi-Yau manifolds similar to those recently studied by Kachru, Kallosh, Linde and Trivedi (KKLT). dS vacuum appears in KKLT model after uplifting an AdS vacuum by adding an anti-D3-brane, which explicitly breaks supersymmetry. We accomplish the same goal by adding fluxes of gauge fields within the D7-branes, which induce a D-term potential in the effective 4D action. In this way we obtain dS space as a spontaneously broken vacuum from a purely supersymmetric 4D action. We argue that our approach can be directly extended to heterotic string vacua, with the dilaton potential obtained from a combination of gaugino condensation and the D-terms generated by anomalous U(1) gauge groups.
We consider the GSO(−)GSO(-)GSO(−) sector of the open superstring using the formalism with four-dimensional hybrid variables. This sector is defined by the world sheet hybrid variables (thetaalpha,barthetadotalpha)(\theta^{\alpha},\bar{\theta}^{\dot\alpha})(thetaalpha,barthetadotalpha) with antiperiodic... more
We consider the GSO(−)GSO(-)GSO(−) sector of the open superstring using the formalism with four-dimensional hybrid variables. This sector is defined by the world sheet hybrid variables (thetaalpha,barthetadotalpha)(\theta^{\alpha},\bar{\theta}^{\dot\alpha})(thetaalpha,barthetadotalpha) with antiperiodic boundary conditions. The corresponding spectrum of states and conditions for physical vertices are described. In particular we construct explicitly the lower level GSO(−)GSO(-)GSO(−) vertex operators corresponding to the tachyon and the massless fermions. Using these new vertices, the tachyon and massless sector contribution to the superstring field theory action of Berkovits is evaluated. In this way we have included the Ramond sector and we end by discussing some features of the action
We discuss some phenomenological aspects of gauged supersymmetric gs\gsgs--models on homogeneous coset-spaces ESO\ESOESO and SO(10)/U(5)SO(10)/U(5)SO(10)/U(5) which are some of the most interesting for phenomenology. We investigate in detail the vacuum... more
We discuss some phenomenological aspects of gauged supersymmetric gs\gsgs--models on homogeneous coset-spaces ESO\ESOESO and SO(10)/U(5)SO(10)/U(5)SO(10)/U(5) which are some of the most interesting for phenomenology. We investigate in detail the vacuum configurations of these models, and study the resulting consequences for supersymmetry breaking and breaking of the internal symmetry. Some supersymmetric minima for both models with gauged full isometry groups E_6E_6E6 and SO(10) are physically problematic as the Kaehler metric becomes singular and hence the kinetic terms of the Goldstone boson multiplets vanish. This leads us to introduce recently proposed soft supersymmetry-breaking mass terms which displace the minimum away from the singular point. A non-singular Kaehler metric breaks the linear subgroup SO(10)timesU(1)SO(10)\times U(1)SO(10)timesU(1) of the E6E_6E_6 model spontaneously. The particle spectrum of all these different models is computed.