Publications by Joseph Conlon

Galaxy cluster thermal x-ray spectra constrain axionlike particles

Physical Review D 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.

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.

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


JP Conlon, AJ Powell

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

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


JP Conlon, FV Day

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


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

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

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.

Anomaly Mediation in Superstring Theory

ArXiv (0)

JP Conlon, M Goodsell, E Palti

We study anomaly mediated supersymmetry breaking in type IIB string theory and use our results to test the supergravity formula for anomaly mediated gaugino masses. We compute 1-loop gaugino masses for models of D3-branes on orbifold singularities with 3-form fluxes by calculating the annulus correlator of 3-form flux and two gauginos in the zero momentum limit. Consistent with supergravity expectations we find both anomalous and running contributions to 1-loop gaugino masses. For background Neveu-Schwarz H-flux we find an exact match with the supergravity formula. For Ramond-Ramond flux there is an off-shell ambiguity that precludes a full matching. The anomaly mediated gaugino masses, while determined by the infrared spectrum, arise from an explicit sum over UV open string winding modes. We also calculate brane-to-brane tree-level gravity mediated gaugino masses and show that there are two contributions coming from the dilaton and from the twisted modes, which are suppressed by the full T^6 volume and the untwisted T^2 volume respectively.

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

Towards Realistic String Vacua From Branes At Singularities

ArXiv (0)

JP Conlon, A Maharana, F Quevedo

We report on progress towards constructing string models incorporating both realistic D-brane matter content and moduli stabilisation with dynamical low-scale supersymmetry breaking. The general framework is that of local D-brane models embedded into the LARGE volume approach to moduli stabilisation. We review quiver theories on del Pezzo $n$ ($dP_n$) singularities including both D3 and D7 branes. We provide supersymmetric examples with three quark/lepton families and the gauge symmetries of the Standard, Left-Right Symmetric, Pati-Salam and Trinification models, without unwanted chiral exotics. We describe how the singularity structure leads to family symmetries governing the Yukawa couplings which may give mass hierarchies among the different generations. We outline how these models can be embedded into compact Calabi-Yau compactifications with LARGE volume moduli stabilisation, and state the minimal conditions for this to be possible. We study the general structure of soft supersymmetry breaking. At the singularity all leading order contributions to the soft terms (both gravity- and anomaly-mediation) vanish. We enumerate subleading contributions and estimate their magnitude. We also describe model-independent physical implications of this scenario. These include the masses of anomalous and non-anomalous U(1)'s and the generic existence of a new hyperweak force under which leptons and/or quarks could be charged. We propose that such a gauge boson could be responsible for the ghost muon anomaly recently found at the Tevatron's CDF detector.

Systematics of Moduli Stabilisation in Calabi-Yau Flux Compactifications

ArXiv (0)

V Balasubramanian, P Berglund, JP Conlon, F Quevedo

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 the potential approaches zero from below, with an associated non-supersymmetric AdS minimum at exponentially large volume. Both this and its de Sitter uplift are tachyon-free, thereby fixing all Kahler and complex structure moduli, which has been difficult to achieve in the KKLT scenario. Also, for the class of vacua described in this paper, the gravitino mass is independent of the flux discretuum, whereas the ratio of the string scale to the 4d Planck scale is hierarchically small but flux dependent. The inclusion of alpha' corrections plays a crucial role in the structure of the potential. We illustrate these ideas through explicit computations for a particular Calabi-Yau manifold.

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

ArXiv (0)

JP Conlon, F Quevedo, K 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 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.