Supersymmetry Breaking Scale Research Articles

Stringy constraints on primordial electromagnetic fields in axion inflation

We study primordial electromagnetic fields in effective actions of string theory. In contrast to a conventional scenario of producing primordial electromagnetic fields induced by the axion inflation, we deal with the Dirac-Born-Infeld action as a non-linear generation of Maxwell theory. It turns out that the intensity of generated electromagnetic fields is bounded from above by the string scale which can also be rewritten in terms of supersymmetry breaking scale in the context of type IIB Large Volume Scenario. The instability parameter ξ is constrained by the tadpole cancellation condition of D3-branes and a realization of hierarchy between the string scale and the Hubble scale of inflation. Hence, the magnetogenesis can be realized in the limited corner of the string landscape due to the O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O} $$\\end{document}(1) value of the coefficient of Chern-Simons coupling.

Hybrid inflation from supersymmetry breaking

We extend a recently proposed framework, dubbed inflation by supersymmetry breaking, to hybrid inflation by introducing a waterfall field that allows to decouple the supersymmetry breaking scale in the observable sector from the inflation scale, while keeping intact the inflation sector and its successful predictions: naturally small slow-roll parameters, small field initial conditions and absence of the pseudo-scalar companion of the inflaton, in terms of one free parameter which is the first order correction to the inflaton Kähler potential. During inflation, supersymmetry is spontaneously broken with the inflaton being the superpartner of the goldstino, together with a massive vector that gauges the R-symmetry. Inflation arises around the maximum of the scalar potential at the origin where R-symmetry is unbroken. Moreover, a nearby minimum with tuneable vacuum energy can be accommodated by introducing a second order correction to the Kähler potential. The inflaton sector can also play the role of the supersymmetry breaking ‘hidden’ sector when coupled to the (supersymmetric) Standard Model, predicting a superheavy superparticle spectrum near the inflation scale. Here we show that the introduction of a waterfall field provides a natural way to end inflation and allows for a scale separation between supersymmetry breaking and inflation. Moreover, the study of the global vacuum describing low energy Standard Model physics can be done in a perturbative way within a region of the parameter space of the model.

Phenomenology of superheavy decaying dark matter from string theory

We study the phenomenology of superheavy decaying dark matter with mass around 1010 GeV which can arise in the low-energy limit of string compactifications. Generic features of string theory setups (such as high scale supersymmetry breaking and epochs of early matter domination driven by string moduli) can accommodate superheavy dark matter with the correct relic abundance. In addition, stringy instantons induce tiny R-parity violating couplings which make dark matter unstable with a lifetime well above the age of the Universe. Adopting a model-independent approach, we compute the flux and spectrum of high-energy gamma rays and neutrinos from three-body decays of superheavy dark matter and constrain its mass-lifetime plane with current observations and future experiments. We show that these bounds have only a mild dependence on the exact nature of neutralino dark matter and its decay channels. Applying these constraints to an explicit string model sets an upper bound of O\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O} $$\\end{document}(0.1) on the string coupling, ensuring that the effective field theory is in the perturbative regime.

Entanglement Negativity in de Sitter Biverse from Stringy Axionic Bell Pair: An Analysis Using Bunch‐Davies Vacuum

AbstractIn this work, signatures of quantum entanglement by computing entanglement negativity between two causally unrelated regions in 3 + 1 dimensional global de Sitter space are studied. A bipartite quantum field theoretic setup for this purpose, driven by an axionic Bell pair resulting from Type IIB string compactification on a Calabi‐Yau three fold is investigated. A spherical surface that divides the spatial slice of the global de Sitter space into exterior and interior causally unrelated sub regions is taken into account. For the computational purpose, the simplest possible initial choice of quantum vacuum, which is Bunch‐Davies state is used. The quantitative quantum information theoretic measure for entanglement negativity turns out be consistent with the results obtained for entanglement entropy, even it is better than that from quantum information theoretic point of view. The problem in a hyperbolic open chart where one of the causally unrelated observers remains constrained and the scale dependence enters to the corresponding quantum information theoretic entanglement measure for axionic Bell pair is designed. From the analysis it is found that in the large scales, initially maximally entangled Bunch‐Davies state turns out to be strongly entangled or weakly entangled depending on the axionic decay constant and the supersymmetry breaking scale. It is also found that at the small scales the initial entanglement can be perfectly recovered. The possibility of having a biverse picture, which is a mini version of the multiverse in the present theoretical set up is discussed. Last but not the least, the necessary criteria for generating non vanishing quantum entanglement measures within the framework of quantum field theory of global de Sitter space as well as well as in primordial cosmology due to the axion derived from string theory are provided.

Comparable dark matter and baryon abundances with a heavy dark sector

We propose a scenario that explains the comparable abundances of dark matter (DM) and baryons without any coincidence in the corresponding particle masses. Here, DM corresponds to heavy “dark baryons” in a hidden MSSM-like dark sector, where the supersymmetry breaking scale can be several orders of magnitude larger than in the visible sector. In both sectors a baryon asymmetry is generated via the Affleck-Dine mechanism, and the smaller dark baryon-to-entropy ratio partially compensates the larger dark baryon masses to give similar densities in the two sectors. The large mass hierarchy also naturally results in an asymmetric reheating of these sequestered sectors. Moreover, this scenario predicts uncorrelated DM and baryon isocurvature perturbations.

Higgs in nilpotent supergravity: Vacuum energy and Festina Lente

In this note we study supergravity models with constrained superfields. We construct a supergravity framework in which all (super)symmetry breaking dynamics happen in vacuum with naturally (or otherwise asymptotically) vanishing energy. Supersymmetry is generically broken in multiple sectors each of them is parametrized by a nilpotent goldstino superfield. Dynamical fields (the Higgs, inflaton, etc) below the supersymmetry breaking scale are constrained superfields of various types. In this framework, there is a dominant supersymmetry breaking sector which uplifts the potential to zero value. Other sources of supersymmetry breaking have (asymptotically) vanishing contribution to vacuum energy such that supersymmetry is locally restored. Demanding vanishing vacuum energy constrains the structure of the superpotential and Kahler potential; there is a superpotential term for each secluded sector directly interacting with a nilpotent superfield and the Kahler potential must have a shift symmetry along Higgs field directions. This structure is inspired by elements that appear in string theory. We also study the Higgs dynamics during inflation and show that the swampland Festina Lente bound could be realized in this framework.

PQ axiverse

We show that the strong CP problem is solved in a large class of compactifications of string theory. The Peccei-Quinn mechanism solves the strong CP problem if the CP-breaking effects of the ultraviolet completion of gravity and of QCD are small compared to the CP-preserving axion potential generated by low-energy QCD instantons. We characterize both classes of effects. To understand quantum gravitational effects, we consider an ensemble of flux compactifications of type IIB string theory on orientifolds of Calabi-Yau hypersurfaces in the geometric regime, taking a simple model of QCD on D7-branes. We show that the D-brane instanton contribution to the neutron electric dipole moment falls exponentially in N4, with N the number of axions. In particular, this contribution is negligible in all models in our ensemble with N > 17. We interpret this result as a consequence of large N effects in the geometry that create hierarchies in instanton actions and also suppress the ultraviolet cutoff. We also compute the CP breaking due to high-energy instantons in QCD. In the absence of vectorlike pairs, we find contributions to the neutron electric dipole moment that are not excluded, but that could be accessible to future experiments if the scale of supersymmetry breaking is sufficiently low. The existence of vectorlike pairs can lead to a larger dipole moment. Finally, we show that a significant fraction of models are allowed by standard cosmological and astrophysical constraints.

Probing supersymmetry breaking scale with atomic clocks

The supersymmetry (SUSY) breaking mechanism inevitably predicts the existence of the sgoldstinos, which can play the role of wave-like dark matter. Due to the ubiquitous coupling to the electromagnetic fields, the light scalar sgoldstino dark matter can lead to the variance of the fine-structure constant. With the precise atomic clock data, we find the SUSY breaking scale F can be probed up to the GUT scale in the sgoldstino mass range of 10−22 eV <mϕ<4×10−7 eV.

The Scale of Supersymmetry Breaking and the Dark Dimension

We argue for a relation between the supersymmetry breaking scale and the measured value of the dark energy density Λ. We derive it by combining two quantum gravity consistency swampland constraints, which tie the dark energy density Λ and the gravitino mass M3/2, respectively, to the mass scale of a light Kaluza-Klein tower and, therefore, to the UV cut-off of the effective theory. Whereas the constraint on Λ has recently led to the Dark Dimension scenario, with a prediction of a single mesoscopic extra dimension of the micron size, we use the constraint on M3/2 to infer the implications of such a scenario for the scale of supersymmetry breaking. We find that a natural scale for supersymmetry signatures isM=OΛ18=OTeV.\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ M=\\mathcal{O}\\left({\\Lambda}^{\\frac{1}{8}}\\right)=\\mathcal{O}\\left(\ extrm{TeV}\\right). $$\\end{document}This mass scale is within reach of LHC and of the next generation of hadron colliders. Finally, we discuss possible string theory and effective supergravity realizations of the Dark Dimension scenario with broken supersymmetry.

More on massive gravitino scattering amplitudes and the unitarity cutoff of the new Fayet-Iliopoulos terms

We extend the 2 → 2 gravitino scattering amplitude computed in [1] to an arbitrary mathcal{N} = 1 supergravity model of one chiral and one vector multiplet, in a Minkowski background with supersymmetry breaking driven by both F- and D-terms. We find that the cancellation of the leading term in mathcal{O} (κ2E4/|m3/2|2), that would lead to a breakdown of perturbative unitarity at a scale Λ ~ MSUSY, is a consequence of the vanishing of the scalar potential at its minimum, which is implied by the flat background. We then analyse the inclusion of the new Fayet-Iliopoulos (FI) terms. We find that, since they modify the scalar potential without contributing to the amplitudes, they generically lead to uncanceled leading terms in the latter and a perturbative cutoff at the supersymmetry breaking scale, except for particular cases where the new FI term does not modify the potential at its minimum and the cutoff is pushed up to the Planck scale.

Quantifying limits on CP violating phases from EDMs in supersymmetry

We revisit the calculation of the electron, neutron, and proton electric dipole moments (EDMs) in the constrained minimal supersymmetric standard model (CMSSM). The relatively large mass of the Higgs boson, mH ≃ 125 GeV coupled with the (as yet) lack of discovery of any supersymmetric particle at the LHC, has pushed the supersymmetry breaking scale to several TeV or higher. Though one might expect this decoupling to have relaxed completely any bounds on the two CP violating phases in the CMSSM (θμ and θA), the impressive experimental improvements in the limits on the EDMs (particularly the electron EDM) still allow us to set constraints of order (0.01−0.1)π on θA and (0.001−0.1)π on θμ. We also discuss the impact of future improvements in the experimental limits on supersymmetric models.

Cosmological imprints of SUSY breaking in models of sgoldstinoless non-oscillatory inflation

In supergravity, the dynamics of the sgoldstino – superpartner of the goldstino superfield associated with the breaking of supersymmetry at low energy – can substantially modify the dynamics of inflation in the primordial Universe. So-called sgoldstinoless models assume the existence of a nilpotency constraint S 2 = 0 that effectively removes the sgoldstino from the theory. Such models were proposed to realise non-oscillatory inflation scenarios with a single scalar field, which feature a long period of kination at the end of inflation, and therefore a non-standard post-inflationary cosmology. Using effective operators, we propose models in which the sgoldstino is stabilized close to the origin to reproduce the nilpotent constraint. We show that small sgoldstino fluctuations may lead to a sizeable back-reaction on the cosmological history. We study the effect of this back-reaction on the inflation observables measured in the cosmic microwave background and confront the model to a series of constraints including limits on ΔN eff. We show that the peculiar form of the potential in the large supersymmetry breaking scale limit can generate peaks in the scalar power spectrum produced from inflation. We study how certain perturbation modes may re-enter the horizon during or after kination and show that a large supersymmetry breaking scale may lead to the formation of primordial black holes with various masses in the early Universe.

Dynamically induced topological inflation

We propose an inflation model in which the inflationary era is driven by the strong dynamics of $Sp(2)$ gauge theory. The quark condensation in the confined phase of $Sp(2)$ gauge theory generates the inflaton potential comparable to the energy of the thermal bath at the time of phase transition. Afterwards, with a super-Planckian field value at the global minimum, the inflation commences at a false vacuum region lying between true vacuum regions and hence the name ``topological inflation.'' Featured by the huge separation between the scale of the false vacuum ($V(0{)}^{1/4}\ensuremath{\sim}{10}^{15}\text{ }\text{ }\mathrm{GeV}$) and the field value at the global minimum (${\ensuremath{\phi}}_{\mathrm{min}}\ensuremath{\sim}{M}_{P}$), the model can be consistent with cosmic microwave background (CMB) observables without suffering from the initial condition problems. Crucially, this is achieved only with some mild tuning of parameters in $V(\ensuremath{\phi})$. In addition to $Sp(2)$, this model is based on an anomaly free ${Z}_{6R}$ discrete $R$ symmetry. Remarkably, while all parameters are fixed by CMB observations, the model predicts a hierarchy of energy scales including the inflation scale, supersymmetry-breaking scale, R-symmetry breaking scale, Higgsino mass and the right-handed neutrino mass given in terms of the dynamical scale of $Sp(2)$.

Joint statistics of cosmological constant and SUSY breaking in flux vacua with nilpotent Goldstino

We obtain the joint distribution of the gravitino mass and the cosmological constant in KKLT and LVS models with anti-D3 brane uplifting described via the nilpotent goldstino formalism. Moduli stabilisation (of both complex structure and Kähler moduli) is incorporated so that we sample only over points corresponding to vacua. Our key inputs are the distributions of the flux superpotential, the string coupling and the hierarchies of warped throats. In the limit of zero cosmological constant, we find that both in KKLT and LVS the distributions are tilted favourably towards lower scales of supersymmetry breaking.

Higgs information in Split-SUSY at the LHC

Information theory turns out to be an interesting tool for studying the consequences of Higgs observations to various new physics candidate theories by means of the information measure as the entropy of Higgs-Boson through its various detection modes at the Large Hadron Collider. The present article investigates the parameter space of a supersymmetric scenario where sfermions and one of the Higgs superfields are decoupled, while the gauginos, Higgsinos, and the remaining Higgs doublet are still allowed to be lighter. Our analysis reveals that this is quite a viable choice in the light of LHC discovery of a Higgs which resembles the SM Higgs-Boson and nothing else so far. While the supersymmetry breaking scale MS could be as high as 1011 GeV or so, the most preferred values of the MS and tan⁡β are found to be around 3.6×107 GeV and 41 respectively, which is also consistent with the relic abundance of the neutralino dark matter. The corresponding value of neutralino (mχ˜10) LSP is estimated to be around 1.01 TeV. The preferred values of other parameters, namely, the Higgsino mass (μ) and gaugino mass parameters (M1 and M2) are found to be about 1.05 TeV, 1.74 TeV, and 2.57 TeV, respectively.

Realization of slow-roll inflation and the MSSM in supergravity theories with new Fayet-Iliopoulos terms

A new supergravity D-term, not associated to gauged R-symmetry, was recently discovered and used to construct new supergravity models. In this paper we use a generalization of the new D-term that we used in previous works, to construct a supergravity model of slow-roll inflation with the observable sector of the minimal supersymmetric standard model. Supersymmetry is broken at a high scale in the hidden sector and communicated to the observable sector by gravity mediation. The new D-term contains free parameters that can give large masses to scalar superpartners of quarks and leptons and to the higgsinos while holding the masses of observed particles fixed. Gauginos receive a mass from a noncanonical kinetic term for the vector supermultiplets. We also present a simple argument proving in full generality that the cutoff $\mathrm{\ensuremath{\Lambda}}$ of effective theories containing new D-terms can never exceed the supersymmetry breaking scale. In our theory, the relation between D-term and the Hubble constant during inflation also implies the universal relation $\mathrm{\ensuremath{\Lambda}}\ensuremath{\lesssim}\sqrt{H{M}_{\mathrm{Pl}}}$.

Gravitational waves from first-order electroweak phase transition in a model with light sgoldstinos

We study previously unexplored possibility of triggering the first order electroweak phase transition (EWPT) by interactions of the Standard Model (SM) particles with the sector responsible for low scale supersymmetry breaking. The low-energy theory apart from the SM particles contains additional scalar degrees of freedom — sgoldstinos — which contribute to the effective scalar potential and thus can trigger the first order EWPT. Remarkably, the latter requires only moderate couplings in the scalar sector. The perturbative description in terms of the effective theory seems formally to be applicable upto the scale of supersymmetry breaking: the Landau pole in the scalar sector is above 108-109 GeV. We calculate the gravitational wave signal generated at this transition (it can be tested, e.g. by LISA, BBO and DECIGO) and briefly discuss the collider phenomenology of this scenario.

Seesaw mechanism in the R-parity-violating supersymmetric standard model with the gauged flavor U(1)X symmetry

Abstract We study the seesaw mechanism in the supersymmetric standard model (SSM) with the ${\mathbb {Z}}_3$ symmetry called matter triality (M3). The Abelian discrete symmetry prohibits the baryon number violation operators at the (non-)renormalizable level, which ensures proton longevity. The cubic coupling by right-handed neutrinos generates the Majorana mass term after the right-handed sneutrinos develop into the vacuum expectation values. Due to the R-parity violation, the active neutrino masses can be generated not only from the mixings with the right-handed neutrinos but also from those with the minimal SSM neutralinos. We propose a model where M3 is embedded in the gauged flavor symmetry. The flavor charges are constrained by the anomaly cancellation conditions and the requirements to realize the fermion masses and mixing angles in the quark and lepton sectors. We analyze the assignments of the flavor charge, and show that the sterile neutrino mass is allowed to be below the soft supersymmetry-breaking scale, which is constrained by the half-lifetime of the neutrinoless double beta decay.

RG-induced modulus stabilization: perturbative de Sitter vacua and improved D3- overline{mathrm{D}3} inflation

We propose a new mechanism that adapts to string theory a perturbative method for stabilizing moduli without leaving the domain of perturbative control, thereby evading the ‘Dine-Seiberg’ problem. The only required nonperturbative information comes from the standard renormalization-group resummation of leading logarithms that allow us simultaneously to work to a fixed order in the perturbative parameter α and to all orders in α ln τ where τ is a large extra-dimensional modulus. The resulting potential is naturally minimized for moduli of order τ ~ e1/α and so can be exponentially large given mathcal{O} (10) input parameters. The mechanism relies on accidental low-energy scaling symmetries known to be generic and so is robust against UV details. The resulting compactifications generically break supersymmetry and 4D de Sitter solutions are relatively easy to achieve without additional uplifting. Variations on the theme lead to inflationary scenarios for which the size of the stabilized moduli differ significantly before and after inflation and so provide a dynamical mechanism whereby inflationary scales are much larger than late-time physical (e.g. supersymmetry breaking) scales, with this hierarchy contingent on past cosmic evolution with the inflaton playing a secondary late-time role as a relaxation field. We apply this formalism to warped D3- overline{mathrm{D}3} inflation using non-linearly realized supersymmetry to describe the antibrane tension and the Coulomb interaction, and show how doing so our perturbative modulus stabilization mechanism evades the η-problem that usually plagues this scenario. We speculate about the relevance of our formalism to tachyon condensation at later stages of brane-antibrane annihilation.

Particle physics and cosmology of the string derived no-scale flipped SU(5)

In a recent paper, we identified a cosmological sector of a flipped SU(5) model derived in the free fermionic formulation of the heterotic superstring, containing the inflaton and the goldstino superfields with a superpotential leading to Starobinsky type inflation, while SU(5){times }U(1) is still unbroken. Here, we study the properties and phenomenology of the vacuum after the end of inflation, where the gauge group is broken to the Standard Model. We identify a set of vacuum expectation values, triggered by the breaking of an anomalous U(1)_A gauge symmetry at roughly an order of magnitude below the string scale, that solve the F and D-flatness supersymmetric conditions up to 6th order in the superpotential which is explicitly computed, leading to a successful particle phenomenology. In particular, all extra colour triplets become superheavy guaranteeing observable proton stability, while the Higgs doublet mass matrix has a massless pair eigenstate with realistic hierarchical Yukawa couplings to quarks and leptons. The supersymmetry breaking scale is constrained to be high, consistent with the non observation of supersymmetry signals at the LHC.