Scientific activities of the various Research Units
- Global embedding of realistic orientifolded quivers:
We shall try to construct concrete type IIB Calabi-Yau compactifications with closed string moduli stabilization, explicit brane set-ups and fluxes which satisfy global consistency conditions and give rise, at the same time, to realistic features like the correct Standard Model gauge group, chiral spectrum and Yukawa couplings, focusing on models where the visible sector lives on D3-branes at orientifolded singularities.
- Open string moduli stabilization:
We will study possible mechanisms to stabilize open string moduli in models with both D7-branes wrapping divisors in the geometric regime and D3-branes at singularities exploiting gauge fluxes and supersymmetry breaking effects from background fluxes.
- Explicit Calabi-Yau examples for inflation:
We will try to provide an explicit and globally consistent Calabi-Yau embedding of very promising inflationary models where the inflaton is a closed string modulus and the eta-problem is solved thanks to the presence of effective shift-symmetries in the moduli space.
- New string inflationary scenarios:
We will investigate the role that new higher order alpha’ and non-perturbative corrections to the moduli scalar potential can have in driving cosmic inflation. We will be interested in particular in models which can give rise to inflation at a high scale with the associated production of observable primordial gravity waves (large tensor-to-scalar ratio). It would also be interesting to study if low-energy supersymmetry can be achieved at the same time in these models.
- Post-inflationary history in string cosmology:
We will try to give a complete characterization of the post-inflationary evolution of our Universe for models where the inflaton is a closed string mode. Key-issues to be studied are reheating, the production of non-thermal neutralino dark matter, axionic dark radiation and baryon asymmetry from the decay of the moduli and the possible axionic origin of dark matter.
- Explicit Calabi-Yau models of axion-like particles:
The aim of this project is to provide an explicit Calabi-Yau embedding of models which explain astrophysical anomalies (like the recently observed 3.5 keV line from galaxy clusters) via the conversion into photons of stringy axion-like particles in astrophysical magnetic fields.
- SUSY-breaking and spectra of superpartners:
We will investigate mechanisms for dynamical supersymmetry breaking in string compactifications with the subsequent generation of soft terms via gravity mediation. The final goal is to derive spectra of supersymmetric particles at low-energies in order to make predictions for the LHC. It would be interesting to correlate this search with the requirement of generating the correct amount of neutralino dark matter from the lightest modulus decay.
- T-dualities in string and field theory:
We plan to reproduce the equations of motion of double field theory (that is the massless effective theory of manifest T-dual double string theory) from a beta-function computation and explore the subsequent alpha' corrections.
- Soft theorems and symnmetries:
We will explore the possibility to get from the soft amplitudes informations not only on the generators of the symmetries underlying the theory but also on their algebra. The higher loops and non perturbative extension of the soft theorems is another arena where these ideas need further investigation.
- Black holes:
We will face the quantum N-portrait issue in relation with recent results on soft graviton scattering amplitudes, the BMS group and the gravitational memory effect. These give rise, classically, to an infinity of vacuum configurations, which may be interpreted as a the configuration space for black hole "hair".
- AdS/CFT correspondence:
We will study 1-loop corrections to non-local supersymmetric operators such as Wilson loops. Discrepancies between some results of the string and gauge theory calculations have been found, which are believed to be attributable to technical aspects of the calculations such as zero modes and different regularization schemes. As a test, we will perform the calculation of the spectra and 1-loop determinants for the fluctuations of D-branes dual to supersymmetric Wilson loop operators, e.g., in ABJM theory.
- String compactifications:
We will analyze symmetries, spectra, interactions, stability, dualities and physical implications of supersymmetric configurations in various compactifications of string theories and their applications to study black holes. Analyze mechanisms and effects of spontaneous supersymmetry breaking in string theory and effective D=4 supergravities, in particular, the role of Volkov-Akulov goldstinos in the construction of phenomenologically relevant supersymmetric models of fundamental particle interactions and cosmology.
We will target at new results on the combined bosonic and fermionic T-duality of superstring sigma models and its non-Abelian generalization, and study properties of superbackgrounds which are subject to symmetry transformations of this kind.
- Fundamental problems in superstring theory:
We plan to look for a formulation of D=6, N=(2,0) superconformal gauge theory related to a still misterious AdS7/CFT6 correspondence and study the relation of higher spin content of string theory to that of higher-spin gauge field theories in AdS with the use of appropriate BRST methods. We will also continue the study of the superstring measure on the supermoduli space.
- Non-perturbative effects in quantum field theories and AdS/CMT:
We will try to further characterize the general properties of (super)conformal theories and exploit new applications to holography. We plan to revisit aspects of AdS/CMT correspondence, with a particular attention to those related to applications for the description of superconductivity phenomena.
Roma Tor Vergata
- Non-perturbative effects in N=2* theories:
We will study the extension to arbitrary gauge groups of the results coming from the conformal anomaly and further explore chiral ring relations in presence of the so called Omega background. The analysis of circular Wilson loops in these gauge theories will also be performed.
- Black Holes in String Theory:
We plan to explore relations between micro-state geometries and open string condensates for a large class of excitations of four dimensional BPS black holes realised in terms of D3-branes intersecting on a six-torus. In such a context, we will focus on the complete multipole expansion of the supergravity solutions at weak coupling from string amplitudes.
- Instanton corrections to gauge theories with N= 2, 4 supersymmetries:
We will formulate exact formulas for Wilson loops, chiral correlators and prepotentials in theories with N=2 supersymmetry as well as low energy effective actions for N=4 theories in the Coulomb branch.
- Scattering amplitudes:
We will analyze non-planar on-shell diagrams in gauge theories and string theories and their applications to effective field theories. Soft behavior of string amplitudes with both open and closed massive strings will be studied as well as one-loop amplitudes in superstring theories with non-maximal supersymmetry in D=4 with the helicity spinor formulation.
- Exotic branes in String/M-theory:
We will explore the role of exotic branes in the investigation of the String/M-theory moduli space, in connection with alternative approaches like generalized geometry and double field theory.
- Non-geometric objects:
We will perform the study of fluxes and exotic branes in string theory model building, in possible generalisations of F-theory and in non-supersymmetric models in string theory.
- The dynamics of string theory at high energy:
We aim at continuing the analysis of string-brane collisions in the Regge limit by addressing questions about curved spacetimes starting from the well-understood framework of perturbative string theory using the string S matrix.
- Light string states:
A deepened analysis of the light stated that appear at D-brane intersections will be performed to explore their potential role in explaining the di-photon excess at 750 GeV seen at LHC.
- Basic issues in the stringy description of D-brane Models:
We plan to explore configurations where branes are not wrapped on factorized torii within string world-sheet formalism once non-abelian twist fields techniques will be developed, compute their correlators and study analogous computations in the Melvin background (dual to the Omega background).
- Non-perturbative effects from Strings (1):
Effective D-instanton effects from the world-sheet formalism will be studied along with the classification of the possible effects due to the interplay with fluxes in brane-world orbifolds or orientifolds models and/or possible effects on the selection of stable supersymmetric vacua.
- Non-perturbative effects from Strings (2):
We will complete the non-perturbative analysis of gravitational duals of N=2 SYM from the microscopic set-up and compute the corrections to the classical D-brane solutions due to D-instantons in the case of N=2* theories or SU(N) superconformal theories at generic points of their Coulomb moduli space. We will also focus on non-perturbative effects in gauge theories with exceptional flavor groups.
- Exact results in N=2 D=4:
We will try to improve the techniques based on the use of modular anomaly equations and S duality properties to compute the exact expressions for physical observables in quiver superconformal gauge theories. Moreover we will explore the possibility of computing exactly the prepotential of superconformal gauge theories in presence of generic Omega deformations. To this aim it would be also relevant to understand the relation of these systems with integrable models and topological string models.
- Scattering amplitudes:
We aim to focus at non-planar scattering amplitudes in supersymmetric theories. Notice that many of the features of planar amplitudes are lost, however a surprising level of structure is still present for non-planar amplitudes which should help handling the problem. We will construct a package in Mathematica which automates many of the recently discovered methods in this field.
- String field theory:
We will clarify the exact relation between OSFT moduli in Siegel gauge and BCFT moduli, construct solution generating operators in OSFT via the use of CFT defects and obtain D-branes effective actions from OSFT.
- CFT in d>2:
We plan to probe N=2 superconformal QFT's with localization and find how they respond to the presence of Wilson loops, defects and surface operators. In particular we will study the properties of Wilson loop correlators and of correlation functions in N=2 superconformal theories and their massive deformations and compare the outcomes of localization techniques combined with S-duality requirements with their role as conformal defects.
- String field theory:
We plan to complete the analysis of analitic solutions, in particular of lumps, in bosonic string field theory and to study effective field theories of SFT vs. the ones arising from higher spin theories to compare the two. Exotic spinors in various dimensions and their second quantization is also a topic which will be analyzed.
- Supersymmetric localization:
We are going to exactly compute operator spectra, partition functions and correlators in strongly-coupled regimes of supersymmetric quantum field theories. The results should find applications to mathematical problems which can be put in relation to supersymmetric field theories (e.g. enumerative geometry), as well as to concrete physical problems, for instance to the computation of the entanglement entropy. Moreover, we plan to study of partition functions on open manifold and factorization properties. The cases of higher dimensional supersymmetric gauge theories will be analyzed in wider detail also to further understand their link to integrable systems and, in general, the study of gauge theory grand canonical partition functions, links to topological strings and geometric engineering will be explored.
- SUSY breaking at strong coupling and Holography:
We will analyze the breaking of Supersymmetry in string theory/D-brane constructions with the aim of understanding multiplet recombination in large N (S)CFT and Holography. This should be obtained by an holographic description of quantum field theories at strong coupling phases with dynamical supersymmetry breaking so that one can study holographycally supersymmetry Ward identities and show how and if a goldstino mode appears in the low energy spectrum. These analysis requires a refinement of holographic renormalisation tecniques for non AdS backgrounds, which can find interesting applications, e.g. to study supersymmetric theories on curved manifolds and their renormalization properties.
- de Sitter moduli stabilisation:
We will study the problem of obtaining de Sitter vacua by generating matter via D3-branes at singularities and the more general one obtained by considering O3-planes on top.
- Probe brane technique for studying the T-brane background:
We expect to be able to extend the construction of A-type singularities to cases with D-type and E-type singularities and to properly formulate the corresponding deformations in the 3d quantum field theory.
We want to face the problem of solving the hypercharge flux problem that is finding a four-form flux in F-theory that breaks the SU(5) GUT group to the Standard Model one, without giving a mass to the hypercharge gauge boson and at the same time preventing unwanted couplings.
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