Soft SUSY Breaking Terms for Chiral Matter in IIB String Compactifications

This paper develops the computation of soft supersymmetry breaking terms for chiral D7 matter fields in IIB Calabi-Yau flux compactifications with stabilised moduli. We determine explicit expressions for soft terms for the single-modulus KKLT scenario and the multiple-moduli large volume scenario. In particular we use the chiral matter metrics for Calabi-Yau backgrounds recently computed in hep-th/0609180. These differ from the better understood metrics for non-chiral matter and therefore give a different structure of soft terms. The soft terms take a simple form depending explicitly on the modular weights of the corresponding matter fields. For the large-volume case we find that in the simplest D7 brane configuration, scalar masses, gaugino masses and A-terms are very similar to the dilaton-dominated scenario. Although all soft masses are suppressed by ln(M_P/m_{3/2}) compared to the gravitino mass, the anomaly-mediated contributions do not compete, being doubly suppressed and thus subdominant to the gravity-mediated tree-level terms. Soft terms are flavour-universal to leading order in an expansion in inverse Kahler moduli. They also do not introduce extra CP violating phases to the effective action. We argue that soft term flavour universality should be a property of the large-volume compactifications, and more generally IIB flux models, in which flavour is determined by the complex structure moduli while supersymmetry is broken by the Kahler moduli. For the simplest large-volume case we run the soft terms to low energies and present some sample spectra and a basic phenomenological analysis.Comment: 40 pages, 9 figures, JHEP style; v2. sentence rephrase

Scanning the Landscape of Flux Compactifications: Vacuum Structure and Soft Supersymmetry Breaking

We scan the landscape of flux compactifications for the Calabi-Yau manifold $\mathbb{P}^4_{[1,1,1,6,9]}$ with two K\" ahler moduli by varying the value of the flux superpotential $W_0$ over a large range of values. We do not include uplift terms. We find a rich phase structure of AdS and dS vacua. Starting with $W_0\sim 1$ we reproduce the exponentially large volume scenario, but as $W_0$ is reduced new classes of minima appear. One of them corresponds to the supersymmetric KKLT vacuum while the other is a new, deeper non-supersymmetric minimum. We study how the bare cosmological constant and the soft supersymmetry breaking parameters for matter on D7 branes depend on $W_0$, for these classes of minima. We discuss potential applications of our results.Comment: draft format remove

Low-Energy Supersymmetry Breaking from String Flux Compactifications: Benchmark Scenarios

Soft supersymmetry breaking terms were recently derived for type IIB string flux compactifications with all moduli stabilised. Depending on the choice of the discrete input parameters of the compactification such as fluxes and ranks of hidden gauge groups, the string scale was found to have any value between the TeV and GUT scales. We study the phenomenological implications of these compactifications at low energy. Three realistic scenarios can be identified depending on whether the Standard Model lies on D3 or D7 branes and on the value of the string scale. For the MSSM on D7 branes and the string scale between 10^12 GeV and 10^17 GeV we find that the LSP is a neutralino, while for lower scales it is the stop. At the GUT scale the results of the fluxed MSSM are reproduced, but now with all moduli stabilised. For the MSSM on D3 branes we identify two realistic scenarios. The first one corresponds to an intermediate string scale version of split supersymmetry. The second is a stringy mSUGRA scenario. This requires tuning of the flux parameters to obtain the GUT scale. Phenomenological constraints from dark matter, (g-2)_mu and BR(b->s gamma) are considered for the three scenarios. We provide benchmark points with the MSSM spectrum, making the models suitable for a detailed phenomenological analysis.Comment: 29 pages, 12 figures, reference adde

Type IIA Orientifolds on General Supersymmetric Z_N Orbifolds

We construct Type IIA orientifolds for general supersymmetric Z_N orbifolds. In particular, we provide the methods to deal with the non-factorisable six-dimensional tori for the cases Z7, Z8, Z8', Z12 and Z12'. As an application of these methods we explicitly construct many new orientifold models.Comment: 48 pages, LaTeX, 14 figures, refs. added, closed string spectra slightly change

Moduli Stabilisation and de Sitter String Vacua from Magnetised D7 Branes

Anomalous U(1)'s are ubiquitous in 4D chiral string models. Their presence crucially affects the process of moduli stabilisation and cannot be neglected in realistic set-ups. Their net effect in the 4D effective action is to induce a matter field dependence in the non-perturbative superpotential and a Fayet-Iliopoulos D-term. We study flux compactifications of IIB string theory in the presence of magnetised D7 branes. These give rise to anomalous U(1)'s that modify the standard moduli stabilisation procedure. We consider simple orientifold models to determine the matter field spectrum and the form of the effective field theory. We apply our results to one-modulus KKLT and multi-moduli large volume scenarios, in particular to the Calabi-Yau P^4_{[1,1,1,6,9]}. After stabilising the matter fields, the effective action for the Kahler moduli can acquire an extra positive term that can be used for de Sitter lifting with non-vanishing F- and D-terms. This provides an explicit realization of the D-term lifting proposal of hep-th/0309187.Comment: 35 pages, 1 figure. v2: Minor changes, references adde

Sparticle Spectra and LHC Signatures for Large Volume String Compactifications

We study the supersymmetric particle spectra and LHC collider observables for the large-volume string models with a fundamental scale of 10^{11} GeV that arise in moduli-fixed string compactifications with branes and fluxes. The presence of magnetic fluxes on the brane world volume, required for chirality, perturb the soft terms away from those previously computed in the dilute-flux limit. We use the difference in high-scale gauge couplings to estimate the magnitude of this perturbation and study the potential effects of the magnetic fluxes by generating many random spectra with the soft terms perturbed around the dilute flux limit. Even with a 40% variation in the high-scale soft terms the low-energy spectra take a clear and predictive form. The resulting spectra are broadly similar to those arising on the SPS1a slope, but more degenerate. In their minimal version the models predict the ratios of gaugino masses to be M_1 : M_2 : M_3=(1.5 - 2) : 2 : 6, different to both mSUGRA and mirage mediation. Among the scalars, the squarks tend to be lighter and the sleptons heavier than for comparable mSUGRA models. We generate 10 fb^{-1} of sample LHC data for the random spectra in order to study the range of collider phenomenology that can occur. We perform a detailed mass reconstruction on one example large-volume string model spectrum. 100 fb^{-1} of integrated luminosity is sufficient to discriminate the model from mSUGRA and aspects of the sparticle spectrum can be accurately reconstructed.Comment: 42 pages, 21 figures. Added references and discussion for section 3. Slight changes in the tex

Large-Volume Flux Compactifications: Moduli Spectrum and D3/D7 Soft Supersymmetry Breaking

We present an explicit calculation of the spectrum of a general class of string models, corresponding to Calabi-Yau flux compactifications with h_{1,2}>h_{1,1}>1 with leading perturbative and non-perturbative corrections, in which all geometric moduli are stabilised as in hep-th/0502058. 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.Comment: 64 pages, 4 figures; v2. references added; v3. typos, reference added, matches published versio