Publications by Joseph Conlon


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.


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

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2015) ARTN 019

JP Conlon, AJ Powell


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

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2015) ARTN 011

D Kraljic, M Rummel, JP Conlon


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

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2015) ARTN 013

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

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2014) ARTN 033

JP Conlon, FV Day


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

JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS (2014) ARTN 026

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


A note on the magnitude of the flux superpotential

JOURNAL OF HIGH ENERGY PHYSICS (2014) ARTN 027

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 supersymmetry breaking in anisotropic LARGE volume compactifications

JOURNAL OF HIGH ENERGY PHYSICS (2013) ARTN 071

S Angus, JP Conlon


Dark radiation in LARGE volume models

PHYSICAL REVIEW D 87 (2013) ARTN 043520

M Cicoli, JP Conlon, F Quevedo


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

Physics Review Letters 111 (2013) 15130

J Conlon, MCD Marsh


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.


Loop corrections to Delta N_eff in large volume models

ArXiv (0)

S Angus, JP Conlon, U Haisch, AJ Powell

In large volume models reheating is driven by the decays of the volume modulus to the visible sector, while the decays to its axion partners result in dark radiation. In this article we discuss the impact of loop corrections on the only model-independent visible decay channel: the decay into Higgs pairs via a Giudice-Masiero term. Including such radiative effects leads to a more precise determination of the relative fraction of dark radiation, since by contrast all loop corrections to the volume axion decay mode are Planck suppressed. Assuming an MSSM spectrum and that the Giudice-Masiero coupling is fixed at the string scale by a shift symmetry in the Higgs sector, we arrive at a prediction for the effective number of neutrinos. The result turns out to be too large to be consistent with data, highly disfavouring the minimal model.


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.


Moduli-Induced Vacuum Destabilisation

ArXiv (0)

JP Conlon, FG Pedro

We look for ways to destabilise the vacuum. We describe how dense matter environments source a contribution to moduli potentials and analyse the conditions required to initiate either decompactification or a local shift in moduli vevs. We consider astrophysical objects such as neutron stars as well as cosmological and black hole singularities. Regrettably neutron stars cannot destabilise realistic Planck coupled moduli, which would require objects many orders of magnitude denser. However gravitational collapse, either in matter-dominated universes or in black hole formation, inevitably leads to a destabilisation of the compact volume causing a super-inflationary expansion of the extra dimensions.


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


Soft SUSY Breaking Terms for Chiral Matter in IIB String Compactifications

ArXiv (0)

JP Conlon, SS Abdussalam, F Quevedo, K Suruliz

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.


Moduli Stabilisation and Applications in IIB String Theory

ArXiv (0)

JP Conlon

This article represents the author's PhD thesis. It describes moduli stabilisation in IIB string theory and applications to phenomenological topics. The first half of the thesis starts with an introductory review. It continues with an account of the statistics of complex structure moduli stabilisation before moving to Kahler moduli stabilisation. It describes in detail the large-volumes models and justifies the assumptions used in their construction. The second half of the thesis is concerned with applications to phenomenological topics. These include supersymmetry breaking and soft terms, inflationary model building and axions.