Publications by Joseph Conlon

Axion decay constants away from the lamppost

Journal of High Energy Physics 2016 (2016)

JP Conlon, S Krippendorf

© 2016, The Author(s).Abstract: It is unknown whether a bound on axion field ranges exists within quantum gravity. We study axion field ranges using extended supersymmetry, in particular allowing an analysis within strongly coupled regions of moduli space. We apply this strategy to Calabi-Yau compactifications with one and two Kähler moduli. We relate the maximally allowable decay constant to geometric properties of the underlying Calabi-Yau geometry. In all examples we find a maximal field range close to the reduced Planck mass (with the largest field range being 3.25 MP). On this perspective, field ranges relate to the intersection and instanton numbers of the underlying Calabi-Yau geometry.

Galaxy cluster thermal x-ray spectra constrain axionlike particles

Physical Review D - Particles, Fields, Gravitation and Cosmology 93 (2016)

JP Conlon, AJ Powell, MCD Marsh

© 2016 American Physical Society.Axionlike particles (ALPs) and photons interconvert in the presence of a magnetic field. At keV energies in the environment of galaxy clusters, the conversion probability can become unsuppressed for light ALPs. Conversion of thermal x-ray photons into ALPs can introduce a steplike feature into the cluster thermal bremsstrahlung spectrum, and we argue that existing x-ray data on galaxy clusters should be sufficient to extend bounds on ALPs in the low-mass region ma1×10-12 eV down to M∼7×1011 GeV, and that for 1011 GeV<M1012 GeV light ALPs give rise to interesting and unique observational signatures that may be probed by existing and upcoming x-ray (and potentially x-ray polarization) observations of galaxy clusters.

ALP conversion and the soft X-ray excess in the outskirts of the Coma cluster


D Kraljic, M Rummel, JP Conlon

Observational consistency and future predictions for a 3.5 keV ALP to photon line


PD Alvarez, JP Conlon, FV Day, MCD Marsh, M Rummel

A 3.55 keV line from DM -> a -> gamma predictions for cool-core and non-cool-core clusters


JP Conlon, AJ Powell

3.55 keV photon lines from axion to photon conversion in the Milky Way and M31


JP Conlon, FV Day

A note on the magnitude of the flux superpotential


M Cicoli, JP Conlon, A Maharana, F Quevedo

3.55 keV photon line and its morphology from a 3.55 keV axionlike particle line

PHYSICAL REVIEW D 90 (2014) ARTN 023540

M Cicoli, JP Conlon, MCD Marsh, M Rummel

Soft X-ray excess in the Coma cluster from a Cosmic Axion Background


S Angus, JP Conlon, MCD Marsh, AJ Powell, LT Witkowski

Excess Astrophysical Photons from a 0.1–1 keV Cosmic Axion Background

Physics Review Letters 111 (2013) 15130

J Conlon, MCD Marsh

Dark radiation in LARGE volume models

PHYSICAL REVIEW D 87 (2013) ARTN 043520

M Cicoli, JP Conlon, F Quevedo

Soft supersymmetry breaking in anisotropic LARGE volume compactifications


S Angus, JP Conlon

Superpotential de-sequestering in string models

Journal of High Energy Physics 2013 (2013)

M Berg, JP Conlon, D Marsh, LT Witkowski

Non-perturbative superpotential cross-couplings between visible sector matter and Kähler moduli can lead to significant flavour-changing neutral currents in compactifications of type IIB string theory. Here, we compute corrections to Yukawa couplings in orbifold models with chiral matter localised on D3-branes and non-perturbative effects on distant D7-branes. By evaluating a threshold correction to the D7-brane gauge coupling, we determine conditions under which the non-perturbative corrections to the Yukawa couplings appear. The flavour structure of the induced Yukawa coupling generically fails to be aligned with the tree-level flavour structure. We check our results by also evaluating a correlation function of two D7-brane gauginos and a D3-brane Yukawa coupling. Finally, by calculating a string amplitude between n hidden scalars and visible matter we show how non-vanishing vacuum expectation values of distant D7-brane scalars, if present, may correct visible Yukawa couplings with a flavour structure that differs from the tree-level flavour structure. © 2013 SISSA, Trieste, Italy.

Cosmological natural selection and the purpose of the universe

Complexity 18 (2013) 48-56

A Gardner, JP Conlon

The cosmological natural selection (CNS) hypothesis holds that the fundamental constants of nature have been fine-tuned by an evolutionary process in which universes produce daughter universes via the formation of black holes. Here, we formulate the CNS hypothesis using standard mathematical tools of evolutionary biology. Specifically, we capture the dynamics of CNS using Price's equation, and we capture the adaptive purpose of the universe using an optimization program. We establish mathematical correspondences between the dynamics and optimization formalisms, confirming that CNS acts according to a formal design objective, with successive generations of universes appearing designed to produce black holes. © 2013 Wiley Periodicals, Inc.

Supersymmetric Radiative Flavour

ArXiv (0)

JP Conlon, FG Pedro

We examine possibilities for the radiative generation of the Yukawa couplings and flavour structure in supersymmetric models in the supersymmetric phase. Not withstanding the non-renormalisation of the Wilsonian superpotential, this can occur through the 2-loop vertex renormalisation of the physical 1PI couplings. We describe this effect and construct models in which this occurs. For models attempting to reproduce the full flavour structure of the Standard Model, we analyse the tension between such models and constraints from low-energy flavour observables. We note that the tension is weakest for the case of generating Dirac neutrino masses.

Moduli redefinitions and moduli stabilisation

Journal of High Energy Physics 2010 (2010)

JP Conlon, FG Pedro

Field redefinitions occur in string compactifications at the one loop level. We review arguments for why such redefinitions occur and study their effect on moduli stabilisation and supersymmetry breaking in the LARGE volume scenario. For small moduli, although the effect of such redefinitions can be larger than that of the α' corrections in both the Kähler and scalar potentials, they do not alter the structure of the scalar potential. For the less well motivated case of large moduli, the redefinitions can dominate all other terms in the scalar potential. We also study the effect of redefinitions on the structure of supersymmetry breaking and soft terms. © SISSA 2010.

Gauge threshold corrections for local type-IIB/F-theory GUTs

PHYSICAL REVIEW D 80 (2009) ARTN 106004

JP Conlon, E Palti

Systematics of String Loop Corrections in Type IIB Calabi-Yau Flux Compactifications

ArXiv (0)

M Cicoli, JP Conlon, F 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 three-folds. We give a low energy interpretation for the conjecture of Berg, Haack and Pajer for the form of the loop corrections to the Kaehler potential. We check the consistency of this interpretation in several examples. We show that for arbitrary Calabi-Yaus, the leading contribution of these corrections to the scalar potential is always vanishing, giving an "extended no-scale structure". This result holds as long as the corrections are homogeneous functions of degree -2 in the 2-cycle volumes. We use the Coleman-Weinberg potential to motivate this cancellation from the viewpoint of low-energy field theory. Finally we give a simple formula for the 1-loop correction to the scalar potential in terms of the tree-level Kaehler metric and the correction to the Kaehler potential. We illustrate our ideas with several examples. A companion paper will use these results in the study of Kaehler moduli stabilisation.

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

ArXiv (0)

SS AbdusSalam, JP Conlon, F Quevedo, K Suruliz

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.

Astrophysical and Cosmological Implications of Large Volume String Compactifications

ArXiv (0)

JP Conlon, F 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 stabilisation leads to an exponentially large volume V ~ 10^{15} l_s^6 and an intermediate string scale m_s ~ 10^{11}GeV, with TeV-scale observable supersymmetry breaking. All K\"ahler moduli except for the overall volume are heavier than the susy breaking scale, with m ~ ln(M_P/m_{3/2}) m_{3/2} ~ (\ln(M_P/m_{3/2}))^2 m_{susy} ~ 500 TeV and, contrary to standard expectations, have matter couplings suppressed only by the string scale rather than the Planck scale. These decay to matter early in the history of the universe, with a reheat temperature T ~ 10^7 GeV, and are free from the cosmological moduli problem (CMP). The heavy moduli have a branching ratio to gravitino pairs of 10^{-30} and do not suffer from the gravitino overproduction problem. The overall volume modulus is a distinctive feature of these models and is an M_{planck}-coupled scalar of mass m ~ 1 MeV and subject to the CMP. A period of thermal inflation can help relax this problem. This field has a lifetime ~ 10^{24}s and can contribute to dark matter. It may be detected through its decays to 2\gamma or e^+e^-. If accessible the e^+e^- decay mode dominates, with Br(\chi \to 2 \gamma) suppressed by a factor (ln(M_P/m_{3/2}))^2. We consider the potential for detection of this field through different astrophysical sources and find that the observed gamma-ray background constrains \Omega_{\chi} <~ 10^{-4}. The decays of this field may generate the 511 keV emission line from the galactic centre observed by INTEGRAL/SPI.