Dr John McDonald

Reader

Research Interests

My research area is the intersection of particle physics and cosmology, known as particle cosmology or astro-particle physics.

My past and present research interests include:

Dark matter models (thermal relic MSSM neutralino and non-thermal gravitino dark matter, Higgs portal gauge singlet scalar dark matter, RH sneutrino condensate dark matter, alternative thermal production ("freeze-in") mechanisms for MeV and keV dark matter), the cosmology of the minimal supersymmetric standard model (MSSM) and its extensions (flat directions, Affleck-Dine baryogenesis and leptogenesis, Q-ball formation and decay, curvatons and right-handed sneutrinos), inflation models (non-minimally coupled scalar inflation ("Higgs Inflation"), sub-Planckian axion inflation, supersymmetric hybrid inflation models, oscillon formation and reheating) and baryogenesis (Affleck-Dine, electroweak, baryon-to-dark matter ratio ("Baryomorphosis")).

My most recent research focuses on the following themes:

(i) Hemispherical asymmetry of the CMB temperature fluctuations

The cosmic microwave background radiation (CMB) is the remnant radiation from the Big Bang. It has a mean temperature T = 2.725 K, on top of which there are temperature fluctuations of magnitude about 1/10000 of the mean temperature. Analysis of the temperature fluctuations observed by NASA's Wilkinson Microwave Anisotropy Probe (WMAP) and ESA's Planck satellite have found that there is an asymmetry in the magnitude of the temperature fluctuations observed on one side of the sky compared to the opposite side, with a 12-14% difference. This is known as the Hemispherical Power Asymmetry. It is not expected to exist in conventional cosmology models, which predict a difference of no more than 6%. I am presently studying unconventional models based on cosmological phase transitions which occur during inflation, which are able to generate an asymmetric scalar field on the scale of the observed Universe. The hope is that this field may be able modulate the CMB temperature fluctuations across the sky, without introducing unwanted features such as a change in the statistics of the microwave fluctuations or a change in the mean CMB temperature.

[Publications: "Isocurvature and Curvaton Perturbations with Red Power Spectrum and Large Hemispherical Asymmetry", arXiv:1305.0525 [astro-ph.CO], JCAP 1307 (2013) 043; "Hemispherical Power Asymmetry from Scale-Dependent Modulated Reheating", arXiv:1309.1122 [astro- ph.CO], JCAP 1311 (2013) 041; "Hemispherical Power Asymmetry from a Space-Dependent Component of the Adiabatic Power Spectrum", arXiv:1403.2076 [astro-ph.CO], Phys.Rev. D89 (2014) 127303; "Negative Running of the Spectral Index, Hemispherical Asymmetry and the Consistency of Planck with Large r", arXiv:1403.6650 [astro-ph.CO], JCAP 1411 (2014) 012.]

(ii) Sub-Planckian inflation models with a large gravitational wave signature

Inflation might be able to generate primordial gravitational waves, whose detection would serve as a 'smoking gun' for inflation as the explanation of the observed structure of the Universe. However, in order to generate a large gravitational wave signal, the simplest inflation models require scalar fields which are larger than the Planck scale, the scale at which quantum gravity effects become large and the new physics associated with the unification of gravity and other particles and forces is expected to become important. Therefore conventional inflation theories which can generate a large gravitational wave signal are expected to break down. This raises the question of whether it is possible to construct inflation models which can generate a large gravitation wave signal but which do not require scalar field values larger than the Planck scale. I am studying field theory inflation models based on simple axion models which achieve this and which make clear predictions for both the magnitude of the gravitational wave signal ("tensor-to-scalar ratio") and the slope of CMB fluctuation spectrum ("scalar spectral index").

[Publications: "Sub-Planckian Two-Field Inflation Consistent with the Lyth Bound", arXiv:1404.4620 [hep-ph], JCAP 1409 (2014) 09, 027; "A Minimal Sub-Planckian Axion Inflation Model with Large Tensor-to-Scalar Ratio", arXiv:1407.7471 [hep-ph], JCAP 1501 (2015) 018; "Signatures of Planck Corrections in a Spiralling Axion Inflation Model", arXiv:1412.6943 [hep-ph].]

Chaotic initial conditions for nonminimally coupled inflation via a conformal factor with a zero
Kim, J., McDonald, J. 15/05/2017 In: Physical Review D. 95, 10, 9 p.
Journal article

The 750 GeV resonance as non-minimally coupled inflaton: unitarity violation and why the resonance is a real singlet scalar
McDonald, J. 10/10/2016 In: Physics Letters B. 761, p. 408-411. 4 p.
Journal article

Warm dark matter via ultra-violet freeze-in: reheating temperature and non-thermal distribution for fermionic Higgs portal dark matter
McDonald, J. 17/08/2016 In: Journal of Cosmology and Astroparticle Physics. 2016, 8, 13 p.
Journal article

Nonminimally coupled inflation with initial conditions from a preinflation anamorphic contracting era
McDonald, J. 12/08/2016 In: Physical Review D. 94, 4, 5 p.
Journal article

WIMP dark matter and unitarity-conserving inflation via a gauge singlet scalar
Kahlhoefer, F., McDonald, J. 9/11/2015 In: Journal of Cosmology and Astroparticle Physics. 2015, 11, 26 p.
Journal article

Signatures of Planck corrections in a spiralling axion inflation model
McDonald, J. 8/05/2015 In: Journal of Cosmology and Astroparticle Physics. 5, 13 p.
Journal article

A minimal sub-Planckian axion inflation model with large tensor-to-scalar ratio
McDonald, J. 01/2015 In: Journal of Cosmology and Astroparticle Physics. 2015, 1, 8 p.
Journal article

Negative running of the spectral index, hemispherical asymmetry and the consistency of Planck with large r
McDonald, J. 11/2014 In: Journal of Cosmology and Astroparticle Physics. 2014, 11, 9 p.
Journal article

Sub-Planckian two-field inflation consistent with the Lyth bound
McDonald, J. 09/2014 In: Journal of Cosmology and Astroparticle Physics. 2014, 9, 9 p.
Journal article

Hemispherical power asymmetry from a space-dependent component of the adiabatic power spectrum
McDonald, J. 26/06/2014 In: Physical Review D. 89, 12, 5 p.
Journal article

Hemispherical power asymmetry from scale-dependent modulated reheating
McDonald, J. 19/11/2013 In: Journal of Cosmology and Astroparticle Physics. 2013, 11, 15 p.
Journal article

Dark matter gravitinos and baryons via Q-ball decay in the gauge-mediated MSSM
Doddato, F., McDonald, J. 3/07/2013 In: Journal of Cosmology and Astroparticle Physics. 2013, 7, 24 p.
Journal article

Isocurvature and curvaton perturbations with red power spectrum and large hemispherical asymmetry
McDonald, J. 07/2013 In: Journal of Cosmology and Astroparticle Physics. 2013, 7, 16 p.
Journal article

Explaining the dark energy, baryon and dark matter coincidence via domain-dependent random densities
McDonald, J. 05/2013 In: Journal of Cosmology and Astroparticle Physics. 2013, 5, 15 p.
Journal article

Baryon-to-dark matter ratio from random angular fields
McDonald, J. 01/2013 In: Journal of Cosmology and Astroparticle Physics. 2013, 1, 12 p.
Journal article

Unitarity-violation in generalized Higgs inflation models
Lerner, R.N., McDonald, J. 11/2012 In: Journal of Cosmology and Astroparticle Physics. 2012, 11, 20 p.
Journal article

Anthropically selected baryon number and isocurvature constraints
McDonald, J. 10/2012 In: Journal of Cosmology and Astroparticle Physics. 2012, 10, 15 p.
Journal article

New Q-ball Solutions in Gauge-Mediation, Affleck-Dine Baryogenesis and Gravitino Dark Matter
Doddato, F., McDonald, J. 20/06/2012 In: Journal of Cosmology and Astroparticle Physics. 12, 6
Journal article

Simultaneous Generation of WIMP Miracle-like Densities of Baryons and Dark Matter
McDonald, J. 10/11/2011 In: Physical Review D. 84, 10, 9 p.
Journal article

Distinguishing Higgs inflation and its variants
N. Lerner, R., McDonald, J. 21/06/2011 In: Physical Review D. 83, 12, 15 p.
Journal article

Affleck-Dine baryogenesis, condensate fragmentation and gravitino dark matter in gauge-mediation with a large messenger mass
Doddato, F., McDonald, J. 06/2011 In: Journal of Cosmology and Astroparticle Physics. 2011, 6, 17 p.
Journal article

Relating the baryon asymmetry to the thermal relic dark matter density
McDonald, J. 12/04/2011 In: Physical Review D. 83, 8, 7 p.
Journal article

A Unitarity-Conserving Higgs Inflation Model
N. Lerner, R., McDonald, J. 19/11/2010 In: Physical Review D. 82, 10, 5 p.
Journal article

Cosmological evolution of scalar fields and gravitino dark matter in gauge mediation at low reheating temperatures
Ferrantelli, A., McDonald, J. 02/2010 In: Journal of Cosmology and Astroparticle Physics. 2010, 2, 21 p.
Journal article

Cosmic Ray Anomalies and Dark Matter Annihilation to Muons via a Higgs Portal Hidden Sector
Kohri, K., McDonald, J., Sahu, N. 28/01/2010 In: Physical Review D. 81, 2, 11 p.
Journal article

Higgs inflation and naturalness
N. Lerner, R., McDonald, J. 2010 In: Journal of Cosmology and Astroparticle Physics. 2010, 4, 10 p.
Journal article

Gauge singlet scalar as inflaton and thermal relic dark matter
N. Lerner, R., McDonald, J. 8/12/2009 In: Physical Review D. 80, 12, 14 p.
Journal article

Enhanced Dark Matter Annihilation Rate for Positron and Electron Excesses from Q-ball Decay
McDonald, J. 6/10/2009 In: Physical Review Letters. 103, 15, 4 p.
Journal article

keV Warm Dark Matter via the Supersymmetric Higgs Portal
McDonald, J., Sahu, N. 21/05/2009 In: Physical Review D. 79, 10, 6 p.
Journal article

Cosmological constraints on unparticles as continuous mass particles.
McDonald, J. 16/03/2009 In: Journal of Cosmology and Astroparticle Physics. 2009, 3, p. 19.
Journal article

Space-dependent step features: transient breakdown of slow-roll, homogeneity, and isotropy during inflation
Lerner, R.N., McDonald, J. 15/01/2009 In: Physical Review D. 79, 2, 11 p.
Journal article

Supersymmetric inflation and baryogenesis via Extra-Flat directions of the MSSM.
McDonald, J., Seto, O. 07/2008 In: Journal of Cosmology and Astroparticle Physics. 2008, 7, p. 15.
Journal article

Z(2)-Singlino Dark Matter in a Portal-Like Extension of the Minimal Supersymmetric Standard Model.
McDonald, J., Sahu, N. 06/2008 In: Journal of Cosmology and Astroparticle Physics. 2008, 6, p. 26.
Journal article

Type II See-Saw at Collider, Lepton Asymmetry and Singlet Scalar Dark Matter.
McDonald, J., Sahu, N., Sarkar, U. 04/2008 In: Journal of Cosmology and Astroparticle Physics. 2008, 4, p. 37.
Journal article

Supergravity and two-field inflation effects in right-handed sneutrino modified D-term inflation.
Lin, C., McDonald, J. 25/03/2008 In: Physical Review D. 77, 6, 9 p.
Journal article

Unparticles: Interpretation and Cosmology.
McDonald, J. 2008
Other contribution

Right-handed sneutrino condensate cold dark matter and the baryon-to-dark matter ratio.
McDonald, J. 2/01/2007 In: Journal of Cosmology and Astroparticle Physics. 2007, 01, p. 001.
Journal article

RH sneutrino condensate CDM and the baryon-to-dark matter ratio.
McDonald, J. 2007
Other

Supergravity Modification of D-term Hybrid Inflation: Solving the Cosmic String and Spectral Index Problem via a Right-Handed Sneutrino.
McDonald, J., Lin, C.M. 1/09/2006 In: Physical Review D. 74, 6, p. 063510.
Journal article

F-term inflation Q-balls
McDonald, J.F. 2006 In: Physical Review D. 73, 043501
Journal article

Simulations of the end of supersymmetric hybrid inflation and nontopological soliton formation.
Broadhead, M., McDonald, J. 15/08/2005 In: Physical Review D. 72, 4, p. 043519.
Journal article

Condition for successful right-handed Majorana Sneutrino curvaton.
McDonald, J. 16/09/2004 In: Physical Review D. 70, 6, 11 p.
Journal article

Flat direction dynamics in a non-topological soliton-dominated universe.
McDonald, J. 08/2004 In: Journal of Cosmology and Astroparticle Physics. 2004, 8, p. 002.
Journal article

Supersymmetric curvatons and phase-induced curvaton fluctuations.
McDonald, J. 19/05/2004 In: Physical Review D. 69, 10, p. 103511.
Journal article

Two-field Q-ball solutions of supersymmetric hybrid inflation.
Broadhead, M., McDonald, J. 2004 In: Physical Review D. 69, 6, p. 063510. 5 p.
Journal article

Curvaton Potential Terms, Scale-Dependent Perturbation Spectra and Chaotic Initial Conditions
McDonald, J. 12/12/2003 In: Journal of Cosmology and Astroparticle Physics. 2003, 12, 8 p.
Journal article

Growth of inflaton perturbations and the post-inflation era in supersymmetric hybrid inflation models
McDonald, J. 15/10/2003 In: Physical Review D. 68, 8, p. 083502. 12 p.
Journal article

Right-handed sneutrinos as curvatons.
McDonald, J. 8/08/2003 In: Physical Review D. 68, 4, 10 p.
Journal article

F-term Hybrid Inflation, the η-problem and Extra Dimensions
McDonald, J. 16/01/2003 In: Journal of High Energy Physics. 2002, 12, 10 p.
Journal article

Inflaton condensate fragmentation in hybrid inflation models
McDonald, J. 22/08/2002 In: Physical Review D. 66, 4, p. 043525. 8 p.
Journal article

Thermally-generated Gauge Singlet Scalars as Self-Interacting Dark Matter.
McDonald, J. 15/02/2002 In: Physical Review Letters. 88, 9, p. 091304. 4 p.
Journal article

Non-thermal dark matter, high energy cosmic rays and late-decaying particles from inflationary quantum fluctuations
McDonald, J. 28/06/2001 In: Physics Letters B. 511, 1, p. 1-10. 10 p.
Journal article

Q-ball evolution, B-ball baryogenesis and the fB problem
McDonald, J. 6/04/2001 In: Journal of High Energy Physics. 2001, 03, p. 022. 23 p.
Journal article

Dynamical cosmological constant from a very recent phase transition
McDonald, J. 25/01/2001 In: Physics Letters B. 498, 3-4, p. 263-271. 9 p.
Journal article

Inflationary Affleck-Dine scalar dynamics and isocurvature perturbations
Enqvist, K., McDonald, J. 13/07/2000 In: Physical Review D. 62, 4, 8 p.
Journal article

Flat direction condensate instabilities in the MSSM
Enqvist, K., Jokinen, A., McDonald, J. 15/06/2000 In: Physics Letters B. 483, 1-3, p. 191-195. 5 p.
Journal article

Naturally Large Cosmological Neutrino Asymmetries in the Minimal Supersymmetric Standard Model
McDonald, J. 22/05/2000 In: Physical Review Letters. 84, 21, p. 4798-4801. 4 p.
Journal article

Reheating temperature and inflaton mass bounds from thermalization after inflation
McDonald, J. 15/04/2000 In: Physical Review D. 61, 8, 5 p.
Journal article

The dynamics of Affleck-Dine condensate collapse
Enqvist, K., McDonald, J. 20/03/2000 In: Nuclear Physics B. 570, 1-2, p. 407-422. 16 p.
Journal article

Symmetry non-restoration via order 10(-10) B and L asymmetries
McDonald, J. 30/09/1999 In: Physics Letters B. 463, 2-4, p. 225-229. 5 p.
Journal article

Observable isocurvature fluctuations from the Affleck-Dine condensate
Enqvist, K., McDonald, J. 27/09/1999 In: Physical Review Letters. 83, 13, p. 2510-2513. 4 p.
Journal article

Positive order-H-2 mass corrections and Affleck-Dine baryogenesis
McDonald, J. 10/06/1999 In: Physics Letters B. 456, 2-4, p. 118-123. 6 p.
Journal article

B-ball baryogenesis and the baryon to dark matter ratio
Enqvist, K., McDonald, J. 11/01/1999 In: Nuclear Physics B. 538, 1-2, p. 321-350. 30 p.
Journal article

MSSM dark matter constraints and decaying B-balls
Enqvist, K., McDonald, J. 12/11/1998 In: Physics Letters B. 440, 1-2, p. 59-65. 7 p.
Journal article

Spontaneous discrete symmetry breaking during inflation and the NMSSM domain wall problem
McDonald, J. 12/10/1998 In: Nuclear Physics B. 530, 1-2, p. 325-345. 21 p.
Journal article

Supersymmetric D-term inflation and B-ball baryogenesis
Enqvist, K., McDonald, J. 12/10/1998 In: Physical Review Letters. 81, 15, p. 3071-3074. 4 p.
Journal article

Q-balls and baryogenesis in the MSSM
Enqvist, K., McDonald, J. 23/04/1998 In: Physics Letters B. 425, 3-4, p. 309-321. 13 p.
Journal article

Can cosmic-ray catalysed vacuum decay dominate over tunnelling?
Enqvist, K., McDonald, J. 9/03/1998 In: Nuclear Physics B. 513, 3, p. 661-678. 18 p.
Journal article

Vacuum stability and electroweak baryogenesis in the MSSM with light stops
McDonald, J. 6/11/1997 In: Physics Letters B. 413, 1-2, p. 30-34. 5 p.
Journal article

ucdcdc-based Affleck-Dine baryogenesis
McDonald, J. 1/04/1997 In: Physical Review D. 55, 7, p. 4240-4251. 12 p.
Journal article

CP violation for electroweak baryogenesis from mixing of standard model and heavy vector quarks
McDonald, J. 15/01/1996 In: Physical Review D. 53, 2, p. 645-654. 10 p.
Journal article

A simple estimate of the effect of diffusion on the baryon number generated in spontaneous baryogenesis models (vol 353, pg 267, 1995)
McDonald, J. 28/12/1995 In: Physics Letters B. 364, 4, p. 246-246. 1 p.
Journal article

Cosmological domain wall evolution and spontaneous CP violation from a gauge singlet scalar sector
McDonald, J. 31/08/1995 In: Physics Letters B. 357, 1-2, p. 19-28. 10 p.
Journal article

Gauge singlet scalars as cold dark matter
McDonald, J. 15/09/1994 In: Physical Review D. 50, 6, p. 3637-3649. 13 p.
Journal article

Electroweak baryogenesis and dark matter via a gauge singlet scalar
McDonald, J. 17/03/1994 In: Physics Letters B. 323, 3-4, p. 339-346. 8 p.
Journal article

Can a Brans-Dicke scalar account for dark matter in extended inflation models?
McDonald, J. 15/09/1993 In: Physical Review D. 48, 6, p. 2462-2476. 15 p.
Journal article

Cosmological limits on deviations from φ2 potentials in oscillating scalar cold dark matter models
McDonald, J. 15/09/1993 In: Physical Review D. 48, 6, p. 2573-2580. 8 p.
Journal article

Relic densities of neutralinos
McDonald, J., Olive, K.A., Srednicki, M. 4/06/1992 In: Physics Letters B. 283, 1-2, p. 80-84. 5 p.
Journal article

Cosmological consequences of dilatons in the electroweak model
McDonald, J. 2/01/1992 In: Physics Letters B. 274, 1, p. 72-78. 7 p.
Journal article

Chaotic inflation driven by a minimally coupled scalar field in Brans-Dicke models
McDonald, J. 15/10/1991 In: Physical Review D. 44, 8, p. 2314-2324. 11 p.
Journal article

Dark matter from an oscillating Brans-Dicke scalar in the extended inflation model
McDonald, J. 15/10/1991 In: Physical Review D. 44, 8, p. 2325-2334. 10 p.
Journal article

Weakly interacting massive particle densities in decaying-particle-dominated cosmology
McDonald, J. 15/02/1991 In: Physical Review D. 43, 4, p. 1063-1068. 6 p.
Journal article

Is neutralino dark matter compatible with flipped SU(5) models?
McDonald, J. 13/07/1989 In: Physics Letters B. 225, 1-2, p. 133-139. 7 p.
Journal article

Cosmological higgsino densities in SUSY models with intermediate mass scales
McDonald, J. 19/01/1989 In: Physics Letters B. 217, 1-2, p. 107-112. 6 p.
Journal article

On E8×E8 superstring based models with SU(3)c×SU(2)L×SU(2)N×U(1)y×U(1)y′ gauge symmetry
McDonald, J. 13/08/1987 In: Physics Letters B. 194, 3, p. 375-384. 10 p.
Journal article

Proton decay via d=5 gluino dressed graphs with flavour diagonal gluino couplings in supergravity models
McDonald, J., Vayonakis, C.E. 21/11/1985 In: Physics Letters B. 163, 1-4, p. 148-154. 7 p.
Journal article

Flat supergravity potentials with non-zero potential energy due to D-terms
McDonald, J., Vayonakis, C.E. 17/01/1985 In: Physics Letters B. 150, 5, p. 357-359. 3 p.
Journal article

Effects of non-minimal gauge kinetic terms in supergravity models
McDonald, J., Vayonakis, C.E. 1984 In: Physics Letters B. 144, 3-4, p. 199-202. 4 p.
Journal article