Publications (91)
A Systematic Approach to Kähler Moduli Stabilisation
Shehu AbdusSalam, Steven Abel, Michele Cicoli +2
Achieving full moduli stabilisation in type IIB string compactifications for generic Calabi-Yau threefolds with hundreds of Kähler moduli is notoriously hard. This is due not just…
Sequestered de Sitter String Scenarios: Soft-terms
Luis Aparicio, Michele Cicoli, Sven Krippendorf +3
We analyse soft supersymmetry breaking in type IIB de Sitter string vacua after moduli stabilisation, focussing on models in which the Standard Model is sequestered from the supers…
Anomalous U(1)'s and Proton Stability in Brane Models
Luis Ibanez, Fernando Quevedo
We consider the most general generation-independent U(1) gauge symmetry consistent with the presence of Yukawa couplings for all quarks and leptons in the SUSY version of the Stand…
Formal Theory: Status and Outlook
Fernando Quevedo
A very brief overview is presented on some of the current most active areas of research in formal aspects of High Energy Physics and Cosmology. Including the recent breakthrough on…
Explicit de Sitter Flux Vacua for Global String Models with Chiral Matter
Michele Cicoli, Denis Klevers, Sven Krippendorf +3
We address the open question of performing an explicit stabilisation of all closed string moduli (including dilaton, complex structure and Kaehler moduli) in fluxed type IIB Calabi…
Wave Functions and Yukawa Couplings in Local String Compactifications
Joseph P. Conlon, Anshuman Maharana, Fernando Quevedo
We consider local models of magnetised D7 branes in IIB string compactifications, focussing on cases where an explicit metric can be written for the local 4-cycle. The presence of…
Towards a Systematic Construction of Realistic D-brane Models on a del Pezzo Singularity
Matthew J. Dolan, Sven Krippendorf, Fernando Quevedo
A systematic approach is followed in order to identify realistic D-brane models at toric del Pezzo singularities. Requiring quark and lepton spectrum and Yukawas from D3 branes and…
String moduli inflation: an overview
Michele Cicoli, Fernando Quevedo
We present an overview of inflationary models derived from string theory focusing mostly on closed string moduli as inflatons. After a detailed discussion of the eta-problem and di…
On the Explicit Construction and Statistics of Calabi-Yau Flux Vacua
Joseph P. Conlon, Fernando Quevedo
We explicitly construct and study the statistics of flux vacua for type IIB string theory on an orientifold of the Calabi-Yau hypersurface , parametrised by two…
Statistical Analysis of Scientific Metrics in High Energy, Cosmology, and Astroparticle Physics in Latin America
Manuel Morales-Alvarado, Fernando Quevedo, Mario Ramos-Hamud +1
We perform a comprehensive statistical analysis of key scientific metrics to evaluate the productivity and impact of research conducted in Latin American countries within the field…
Astrophysical and Cosmological Implications of Large Volume String Compactifications
Joseph P. Conlon, Fernando Quevedo
We study the spectrum, couplings and cosmological and astrophysical implications of the moduli fields for the class of Calabi-Yau IIB string compactifications for which moduli stab…
D-branes at Toric Singularities: Model Building, Yukawa Couplings and Flavour Physics
Sven Krippendorf, Matthew J. Dolan, Anshuman Maharana +1
We discuss general properties of D-brane model building at toric singularities. Using dimer techniques to obtain the gauge theory from the structure of the singularity, we extract…
Radiative Fermion Masses in Local D-Brane Models
C. P. Burgess, Sven Krippendorf, Anshuman Maharana +1
In the context of D-brane model building, we present a realistic framework for generating fermion masses that are forbidden by global symmetries. We show that the string theoretica…
Dualities in 3D Large Vector Models
Nouman Muteeb, Leopoldo A. Pando Zayas, Fernando Quevedo
Using an explicit path integral approach we derive non-abelian bosonization and duality of 3D systems in the large limit. We first consider a fermionic vector model coup…
Global String Embeddings for the Nilpotent Goldstino
Iñaki GarcÃa-Etxebarria, Fernando Quevedo, Roberto Valandro
We discuss techniques for embedding a nilpotent Goldstino sector both in weakly coupled type IIB compactifications and F-theory models at arbitrary coupling, providing examples of…
Noncompact Coset Spaces in String Theory
Fernando Quevedo
A brief overview of strings propagating on noncompact coset spaces G/H is presented in terms of WZW models. The role played by isometries in the existence of target space duality a…
Scanning the Landscape of Flux Compactifications: Vacuum Structure and Soft Supersymmetry Breaking
Shehu S. AbdusSalam, Joseph P. Conlon, Fernando Quevedo +1
We scan the landscape of flux compactifications for the Calabi-Yau manifold with two K\" ahler moduli by varying the value of the flux superpotential $…
Back to the origins of brane-antibrane inflation
Michele Cicoli, Christopher Hughes, Ahmed Rakin Kamal +4
We study a new framework for brane-antibrane inflation where moduli stabilisation relies purely on perturbative corrections to the effective action. This guarantees that the model…
The Web of D-branes at Singularities in Compact Calabi-Yau Manifolds
Michele Cicoli, Sven Krippendorf, Christoph Mayrhofer +2
We present novel continuous supersymmetric transitions which take place among different chiral configurations of D3/D7 branes at singularities in the context of type IIB Calabi-Yau…
Strings on Curved Spacetimes: Black Holes, Torsion, and Duality
Paul Ginsparg, Fernando Quevedo
We present a general discussion of strings propagating on noncompact coset spaces in terms of gauged WZW models, emphasizing the role played by isometries in the existence of…
Rediscovering the Standard Model with AI
Aya Abdelhaq, Pellegrino Piantadosi, Fernando Quevedo
We investigate whether artificial intelligence can autonomously recover known structures of the Standard Model of particle physics using only experimental data and without theoreti…
Personal Reminiscences of Steven Weinberg
Fernando Quevedo
My personal recollections are presented regarding my interactions with Steven Weinberg and the impact he had in my career from when I was his graduate student until the present.
Warped Tachyonic Inflation in Type IIB Flux Compactifications and the Open-String Completeness Conjecture
Daniel Cremades, Fernando Quevedo, Aninda Sinha
We consider a cosmological scenario within the KKLT framework for moduli stabilization in string theory. The universal open string tachyon of decaying non-BPS D-brane configuration…
Is String Phenomenology an Oxymoron?
Fernando Quevedo
A brief discussion is presented assessing the achievements and challenges of string phenomenology: the subfield dedicated to study the potential for string theory to make contact w…
Duality and Global Symmetries
Fernando Quevedo
This is a general introduction to duality in field theories. The existence and breaking of global symmetries is used as a guideline to systematically prove duality between differen…
General Analysis of LARGE Volume Scenarios with String Loop Moduli Stabilisation
Michele Cicoli, Joseph P. Conlon, Fernando Quevedo
We study the topological conditions for general Calabi-Yaus to get a non-supersymmetric AdS exponentially large volume minimum of the scalar potential in flux compactifications of…
Kahler Potentials of Chiral Matter Fields for Calabi-Yau String Compactifications
Joseph P. Conlon, Daniel Cremades, Fernando Quevedo
The Kahler potential is the least understood part of effective N=1 supersymmetric theories derived from string compactifications. Even at tree-level, the Kahler potential for the p…
Quantum Transitions, Detailed Balance, Black Holes and Nothingness
Sebastian Cespedes, Senarath de Alwis, Francesco Muia +1
We consider vacuum transitions by bubble nucleation among 4D vacua with different values and signs of the cosmological constant , including both up and down tunnelings. Followi…
On de Sitter String Vacua from Anti-D3-Branes in the Large Volume Scenario
Chiara Crinò, Fernando Quevedo, Roberto Valandro
We consider de Sitter vacua realised in concrete type IIB Calabi-Yau compactifications with an anti D3-brane at the tip of a warped throat of Klebanov-Strassler type. The Kähler m…
Duality Symmetries from Non--Abelian Isometries in String Theories
Xenia C. de la Ossa, Fernando Quevedo
In string theory it is known that abelian isometries in the sigma model lead to target space duality. We generalize this duality to backgrounds with non--abelian isometries. The pr…
Systematics of the Expansion in F-Theory
Michele Cicoli, Fernando Quevedo, Raffaele Savelli +2
Extracting reliable low-energy information from string compactifications notoriously requires a detailed understanding of the UV sensitivity of the corresponding effective field th…
Light Axiodilatons: Matter Couplings, Weak-Scale Completions and Long-Distance Tests of Gravity
Philippe Brax, Cliff Burgess, Fernando Quevedo
We consider the physical implications of very light axiodilatons motivated by a novel mechanism to substantially reduce the vacuum energy proposed in arXiv:2110.10352. We address t…
Testing BSM Physics with Gravitational Waves
Francesco Muia, Fernando Quevedo, Andreas Schachner +1
The Cosmic Gravitational Wave Background (CGWB) is an irreducible background of gravitational waves generated by particle exchange in the early Universe plasma. Standard Model part…
Kahler Moduli Inflation
Joseph P. Conlon, Fernando Quevedo
We show that under general conditions there is at least one natural inflationary direction for the Kahler moduli of type IIB flux compactifications. This requires a Calabi-Yau whic…
Volume Modulus Inflation and the Gravitino Mass Problem
Joseph P. Conlon, Renata Kallosh, Andrei Linde +1
The Hubble constant during the last stages of inflation in a broad class of models based on the KKLT mechanism should be smaller than the gravitino mass, H <~ m_{3/2}. We point out…
Condensation of p-branes and generalized Higgs/confinement duality
Fernando Quevedo, Carlo Trugenberger
We review our recent work on the low-energy actions and the realizations of strong-weak coupling dualities in non-perturbative phases of compact antisymmetric tensor field theories…
Abelian and Non-Abelian Dualities in String Bacgrounds
Fernando Quevedo
We present a brief discussion of recent work on duality symmetries in non-trivial string backgrounds. Duality is obtained from a gauged non-linear sigma-model with vanishing gauge…
Higher Derivative Corrections to String Inflation
Michele Cicoli, Matteo Licheri, Pellegrino Piantadosi +2
We quantitatively estimate the leading higher derivative corrections to supergravity derived from IIB string compactifications and study how they may affect modul…
A Database of Calabi-Yau Orientifolds and the Size of D3-Tadpoles
Chiara Crinò, Fernando Quevedo, Andreas Schachner +1
The classification of 4D reflexive polytopes by Kreuzer and Skarke allows for a systematic construction of Calabi-Yau hypersurfaces as fine, regular, star triangulations (FRSTs). U…
D-Branes at del Pezzo Singularities: Global Embedding and Moduli Stabilisation
Michele Cicoli, Sven Krippendorf, Christoph Mayrhofer +2
In the context of type IIB string theory we combine moduli stabilisation and model building on branes at del Pezzo singularities in a fully consistent global compactification. By m…
Non-thermal CMSSM with a 125 GeV Higgs
Luis Aparicio, Michele Cicoli, Bhaskar Dutta +4
We study the phenomenology of the CMSSM/mSUGRA with non-thermal neutralino dark matter. Besides the standard parameters of the CMSSM we include the reheating temperature as an extr…
Gaugino Condensation, Duality and Supersymmetry Breaking
Fernando Quevedo
The status of gaugino condensation in low-energy string theory is reviewed. Emphasis is given to the determination of the efective action below condensation scale in terms of the 2…
Periods for Calabi--Yau and Landau--Ginzburg Vacua
Per Berglund, Philip Candelas, Xenia de la Ossa +4
The complete structure of the moduli space of \cys\ and the associated Landau-Ginzburg theories, and hence also of the corresponding low-energy effective theory that results from (…
Moduli Stabilization in String Theory
Liam McAllister, Fernando Quevedo
We give an overview of moduli stabilization in compactifications of string theory. We summarize current methods for construction and analysis of vacua with stabilized moduli, and w…
The Dilaton Potential from N= 1*
Anamaria Font, Matthias Klein, Fernando Quevedo
Recent understanding of {\cal N}=1* supersymmetric theory (mass deformed {\cal N}=4) has made it possible to find an exact superpotential which encodes the properties of the differ…
D3/D7 Branes at Singularities: Constraints from Global Embedding and Moduli Stabilisation
Michele Cicoli, Sven Krippendorf, Christoph Mayrhofer +2
In the framework of type IIB string compactifications on Calabi-Yau orientifolds we describe how to construct consistent global embeddings of models with fractional D3-branes and c…
Superstring Phenomenology: An Overview
Fernando Quevedo
The different aspects of superstring phenomenology before and after 1995 are briefly reviewed. (Contribution to the conference SUSY97)
Metastable SUSY Breaking, de Sitter Moduli Stabilisation and Kähler Moduli Inflation
Sven Krippendorf, Fernando Quevedo
We study the influence of anomalous U(1) symmetries and their associated D-terms on the vacuum structure of global field theories once they are coupled to N=1 supergravity and in t…
Towards Realistic String Vacua From Branes At Singularities
Joseph P. Conlon, Anshuman Maharana, Fernando Quevedo
We report on progress towards constructing string models incorporating both realistic D-brane matter content and moduli stabilisation with dynamical low-scale supersymmetry breakin…
String Theory Realizations of the Nilpotent Goldstino
Renata Kallosh, Fernando Quevedo, Angel M. Uranga
We describe in detail how the spectrum of a single anti-D3-brane in four-dimensional orientifolded IIB string models reproduces precisely the field content of a nilpotent chiral su…
Low-Energy Supersymmetry Breaking from String Flux Compactifications: Benchmark Scenarios
Benjamin C. Allanach, Fernando Quevedo, Kerim Suruliz
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 paramet…
De Sitter vs Quintessence in String Theory
Michele Cicoli, Senarath de Alwis, Anshuman Maharana +2
De Sitter solutions have been recently conjectured to be incompatible with quantum gravity. In this paper we critically assess the progress and challenges of different mechanisms t…
Putting the Boot into the Swampland
Joseph P. Conlon, Fernando Quevedo
The swampland program of delineating the space of effective field theories consistent with quantum gravity appears similar to the bootstrap program of delineating the space of quan…
Oscillons from String Moduli
Stefan Antusch, Francesco Cefala, Sven Krippendorf +3
A generic feature of string compactifications is the presence of many scalar fields, called moduli. Moduli are usually displaced from their post-inflationary minimum during inflati…
Soft SUSY Breaking Terms for Chiral Matter in IIB String Compactifications
Joseph P. Conlon, Shehu S. Abdussalam, Fernando Quevedo +1
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 e…
Systematics of String Loop Corrections in Type IIB Calabi-Yau Flux Compactifications
Michele Cicoli, Joseph P. Conlon, Fernando Quevedo
We study the behaviour of the string loop corrections to the N=1 4D supergravity Kaehler potential that occur in flux compactifications of IIB string theory on general Calabi-Yau t…
Global Orientifolded Quivers with Inflation
Michele Cicoli, Iñaki GarcÃa-Etxebarria, Christoph Mayrhofer +3
We describe global embeddings of fractional D3 branes at orientifolded singularities in type IIB flux compactifications. We present an explicit Calabi-Yau example where the chiral…
Moduli Vacuum Misalignment and Precise Predictions in String Inflation
Michele Cicoli, Koushik Dutta, Anshuman Maharana +1
The predictions for all the cosmological observables of any inflationary model depend on the number of e-foldings which is sensitive to the post-inflationary history of the univers…
Light Higgsino Dark Matter from Non-thermal Cosmology
Luis Aparicio, Michele Cicoli, Bhaskar Dutta +2
We study the scenario of higgsino dark matter in the context of a non-standard cosmology with a period of matter-domination prior to Big-Bang nucleosynthesis. Matter-domination cha…
The Fate of Dense Scalar Stars
Francesco Muia, Michele Cicoli, Katy Clough +3
Long-lived pseudo-solitonic objects, known as oscillons/oscillatons, which we collectively call real scalar stars, are ubiquitous in early Universe cosmology of scalar field theori…
Cambridge Lectures on Supersymmetry and Extra Dimensions
Sven Krippendorf, Fernando Quevedo, Oliver Schlotterer
These lectures on supersymmetry and extra dimensions are aimed at finishing undergraduate and beginning postgraduate students with a background in quantum field theory and group th…
Gaugino and Scalar Masses in the Landscape
Joseph P. Conlon, Fernando Quevedo
In this letter we demonstrate the genericity of suppressed gaugino masses M_a \sim m_{3/2}/ln(M_P/m_{3/2}) in the IIB string landscape, by showing that this relation holds for D7-b…
Baryon Asymmetry, Supersymmetry and Gravitational Anomalies
Luis E. Ibanez, Fernando Quevedo
We discuss two independent issues about the baryon asymmetry of the universe. First, assuming that it is generated by an unspecified source at high temperatures, we study the effec…
Systematics of Moduli Stabilisation in Calabi-Yau Flux Compactifications
Vijay Balasubramanian, Per Berglund, Joseph P. Conlon +1
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 th…
UV Shadows in EFTs: Accidental Symmetries, Robustness and No-Scale Supergravity
C. P. Burgess, Michele Cicoli, David Ciupke +2
We argue that accidental approximate scaling symmetries are robust predictions of weakly coupled string vacua, and show that their interplay with supersymmetry and other (generalis…
A Comment on Continuous Spin Representations of the Poincaré Group and Perturbative String Theory
Anamaria Font, Fernando Quevedo, Stefan Theisen
We make a simple observation that the massless continuous spin representations of the Poincaré group are not present in perturbative string theory constructions. This represents o…
Gravitational Waves from High Temperature Strings
Andrew R. Frey, Ratul Mahanta, Anshuman Maharana +2
We study finite temperature effects in string cosmology and their potential gravitational wave signature. Expanding on our recent work arXiv:2310.11494 , we consider a general conf…
Density Perturbations and Primordial Non-Gaussianities in a Closed Universe
Sebastian Cespedes, Senarath de Alwis, Francesco Muia +1
The spatial curvature of the universe is not yet known. Even though at present the Universe is very close to being essentially flat and most signatures of curvature appear to have…
Moduli Stabilisation with Nilpotent Goldstino: Vacuum Structure and SUSY Breaking
Luis Aparicio, Fernando Quevedo, Roberto Valandro
We study the effective field theory of KKLT and LVS moduli stabilisation scenarios coupled to an anti-D3-brane at the tip of a warped throat. We describe the presence of the anti-b…
Challenges and Opportunities of Gravitational Wave Searches above 10 kHz
Nancy Aggarwal, Odylio D. Aguiar, Diego Blas +34
The first direct measurement of gravitational waves by the LIGO and Virgo collaborations has opened up new avenues to explore our Universe. This white paper outlines the challenges…
Moduli Stars
Sven Krippendorf, Francesco Muia, Fernando Quevedo
We explore the possibility that (Bose-Einstein) condensation of scalar fields from string compactifications can lead to long-lived compact objects. Depending on the type of scalar…
The Standard Model Quiver in de Sitter String Compactifications
Michele Cicoli, Iñaki GarcÃa Etxebarria, Fernando Quevedo +3
We argue that the Standard Model quiver can be embedded into compact Calabi-Yau geometries through orientifolded D3-branes at del Pezzo singularities with …
Lectures on Superstring Phenomenology
Fernando Quevedo
The phenomenological aspects of string theory are briefly reviewed. Emphasis is given to the status of 4D string model building, effective Lagrangians, model independent results, s…
Duality Beyond Global Symmetries: the Fate of the B_{μν} Field
Fernando Quevedo
Duality between the `axion' field and the antisymmetric tensor field is traced after a nonperturbative effect, gaugino condensation, breaks the Peccei-Quinn symmetry…
Quantum Transitions Between Minkowski and de Sitter Spacetimes
Senarath P. de Alwis, Francesco Muia, Veronica Pasquarella +1
Quantum transitions among de Sitter and Minkowski spacetimes through bubble nucleation are revisited using the Hamiltonian formalism. We interpret tunnelling probabilities as relat…
On KKLT/CFT and LVS/CFT Dualities
Senarath de Alwis, Rajesh Kumar Gupta, Fernando Quevedo +1
We present a general discussion of the properties of three dimensional CFT duals to the AdS string theory vacua coming from type IIB Calabi-Yau flux compactifications. Both KKLT an…
Supersymmetry Protects the Primordial Baryon Asymmetry
Luis E. Ibanez, Fernando Quevedo
It has been argued that any primordial B+L asymmetry existing at very high temperatures can be subsequently erased by anomalous electroweak effects. We argue that this is not neces…
Cosmology, Decoherence and the Second Law
Sebastian Cespedes, Senarath de Alwis, Fernando Quevedo
We consider quantum decoherence and entropy increase in early universe cosmology. We first study decoherence in a discrete bipartite quantum system for which a single qubit gets en…
Joseph Polchinski: A Biographical Memoir
Raphael Bousso, Fernando Quevedo, Steven Weinberg
Joseph Polchinski (1954-2018), one of the the leading theoretical physicists of the past 50 years, was an exceptionally broad and deep thinker. He made fundamental contributions to…
Cambridge Lectures on The Standard Model
Fernando Quevedo, Andreas Schachner
These lecture notes cover the Standard Model (SM) course for Part III of the Cambridge Mathematical Tripos, taught during the years 2020-2023. The course comprised 25 lectures and…
Lorentzian Vacuum Transitions: Open or Closed Universes?
Sebastian Cespedes, Senarath P. de Alwis, Francesco Muia +1
We consider the generalisation of quantum tunneling transitions in the WKB approximation to the time-independent functional Schrödinger and Wheeler-DeWitt equations. Following a L…
Dark Radiation in LARGE Volume Models
Michele Cicoli, Joseph P. Conlon, Fernando Quevedo
We consider reheating driven by volume modulus decays in the LARGE Volume Scenario. Such reheating always generates non-zero dark radiation through the decays to the axion partner,…
A Note on the Magnitude of the Flux Superpotential
Michele Cicoli, Joseph P. Conlon, Anshuman Maharana +1
The magnitude of the flux superpotential plays a crucial role in determining the scales of IIB string compactifications after moduli stabilisation. It has been argued th…
De Sitter from T-branes
Michele Cicoli, Fernando Quevedo, Roberto Valandro
Hidden sector D7-branes with non-zero gauge flux are a generic feature of type IIB compactifications. A non-vanishing Fayet-Iliopoulos term induced by non-zero gauge flux leads to…
Vacuum Transitions in Two-Dimensions and their Holographic Interpretation
Veronica Pasquarella, Fernando Quevedo
We calculate amplitudes for 2D vacuum transitions by means of the Euclidean methods of Coleman-De Luccia (CDL) and Brown-Teitelboim (BT), as well as the Hamiltonian formalism of Fi…
String Thermodynamics In and Out of Equilibrium: Boltzmann Equations and Random Walks
Andrew R. Frey, Ratul Mahanta, Anshuman Maharana +3
We revisit the study of string theory close to the Hagedorn temperature with the aim towards cosmological applications. We consider interactions of open and closed strings in a gas…
Local String Models and Moduli Stabilisation
Fernando Quevedo
A brief overview is presented of the progress made during the past few years on the general structure of local models of particle physics from string theory including: moduli stabi…
Large-Volume Flux Compactifications: Moduli Spectrum and D3/D7 Soft Supersymmetry Breaking
Joseph P. Conlon, Fernando Quevedo, Kerim Suruliz
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 pertu…
Coexisting Flux String Vacua from Numerical Kähler Moduli Stabilisation
Shehu AbdusSalam, Christopher Hughes, Fernando Quevedo +1
We present a comprehensive study of Kähler moduli stabilisation in Type IIB flux compactifications, combining advanced numerical techniques with analytical methods. Our JAX-based…
String Cosmology: from the Early Universe to Today
Michele Cicoli, Joseph P. Conlon, Anshuman Maharana +3
We review applications of string theory to cosmology, from primordial times to the present-day accelerated expansion. Starting with a brief overview of cosmology and string compact…
Phases of Antisymmetric Tensor Field Theories
Fernando Quevedo, Carlo Trugenberger
We study the different phases of field theories of compact antisymmetric tensors of rank in arbitrary space-time dimensions . Starting in a `Coulomb' phase, topologica…