Abstract
One often hears that the strong CP problem is the one problem which cannot be solved by anthropic reasoning. We argue that this is not so. Due to nonperturbative dynamics, states with a different CP violating paramenter θ acquire different vacuum energies after the QCD phase transition. These add to the total variation of the cosmological constant in the putative landscape of Universes. An interesting possibility arises when the cosmological constant is mostly cancelled by the membrane nucleation mechanism. If the step size in the resulting discretuum of cosmological constants, ΔΛ, is in the interval (meV)4< ΔΛ < (100 MeV)4, the cancellation of vacuum energy can be assisted by the scanning of θ. For (meV)4< ΔΛ < (keV)4 this may yield θ < 10−10, meeting the observational limits. This scenario opens up 24 orders of magnitude of acceptable parameter space for ΔΛ compared to membrane nucleation acting alone. In such a Universe one may not need a light axion to solve the strong CP problem.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
P.C.W. Davies and S.D. Unwin, Why is the cosmological constant so small, Proc. Roy. Soc. 377 (1981) 147.
A.D. Linde, The inflationary universe, Rept. Prog. Phys. 47 (1984) 925 [INSPIRE].
T. Banks, TCP, quantum gravity, the cosmological constant and all that. . . , Nucl. Phys. B 249 (1985) 332 [INSPIRE].
S. Weinberg, Anthropic bound on the cosmological constant, Phys. Rev. Lett. 59 (1987) 2607 [INSPIRE].
N. Kaloper and A. Padilla, Sequestering the standard model vacuum energy, Phys. Rev. Lett. 112 (2014) 091304 [arXiv:1309.6562] [INSPIRE].
N. Kaloper, A. Padilla, D. Stefanyszyn and G. Zahariade, Manifestly local theory of vacuum energy sequestering, Phys. Rev. Lett. 116 (2016) 051302 [arXiv:1505.01492] [INSPIRE].
R. Harnik, G.D. Kribs and G. Perez, A universe without weak interactions, Phys. Rev. D 74 (2006) 035006 [hep-ph/0604027] [INSPIRE].
S.L. Adler, Axial vector vertex in spinor electrodynamics, Phys. Rev. 177 (1969) 2426.
J.S. Bell and R. Jackiw, A PCAC puzzle: π 0 → γγ in the σ model, Nuovo Cim. A 60 (1969) 47 [INSPIRE].
G. ’t Hooft, Naturalness, chiral symmetry, and spontaneous chiral symmetry breaking, NATO Sci. Ser. B 59 (1980) 135.
R.J. Crewther, P. Di Vecchia, G. Veneziano and E. Witten, Chiral estimate of the electric dipole moment of the neutron in quantum chromodynamics, Phys. Lett. B 88 (1979) 123 [Erratum ibid. B 91 (1980) 487].
M. Pospelov and A. Ritz, Theta induced electric dipole moment of the neutron via QCD sum rules, Phys. Rev. Lett. 83 (1999) 2526 [hep-ph/9904483] [INSPIRE].
F.K. Guo et al., The electric dipole moment of the neutron from 2+1 flavor lattice QCD, Phys. Rev. Lett. 115 (2015) 062001 [arXiv:1502.02295] [INSPIRE].
R.D. Peccei and H.R. Quinn, CP conservation in the presence of instantons, Phys. Rev. Lett. 38 (1977) 1440 [INSPIRE].
S. Weinberg, A new light boson?, Phys. Rev. Lett. 40 (1978) 223 [INSPIRE].
F. Wilczek, Problem of strong P and T invariance in the presence of instantons, Phys. Rev. Lett. 40 (1978) 279 [INSPIRE].
A.E. Nelson, Naturally weak CP violation, Phys. Lett. B 136 (1984) 387.
S.M. Barr, Solving the strong CP problem without the Peccei-Quinn symmetry, Phys. Rev. Lett. 53 (1984) 329 [INSPIRE].
T. Banks, M. Dine and E. Gorbatov, Is there a string theory landscape?, JHEP 08 (2004) 058 [hep-th/0309170] [INSPIRE].
J.F. Donoghue, Dynamics of M-theory vacua, Phys. Rev. D 69 (2004) 106012 [Erratum ibid. D 69 (2004) 129901] [hep-th/0310203] [INSPIRE].
J.F. Donoghue, The fine-tuning problems of particle physics and anthropic mechanisms, in Universe or multiverse, B. Carr ed., Cambridge University Press, Cambridg U.K. (2007), arXiv:0710.4080 [INSPIRE].
R. Bousso and J. Polchinski, Quantization of four form fluxes and dynamical neutralization of the cosmological constant, JHEP 06 (2000) 006 [hep-th/0004134] [INSPIRE].
J.D. Brown and C. Teitelboim, Dynamical neutralization of the cosmological constant, Phys. Lett. B 195 (1987) 177 [INSPIRE].
J.D. Brown and C. Teitelboim, Neutralization of the cosmological constant by membrane creation, Nucl. Phys. B 297 (1988) 787 [INSPIRE].
T. Banks, M. Dine and N. Seiberg, Irrational axions as a solution of the strong CP problem in an eternal universe, Phys. Lett. B 273 (1991) 105 [hep-th/9109040] [INSPIRE].
S.R. Coleman and F. De Luccia, Gravitational effects on and of vacuum decay, Phys. Rev. D 21 (1980) 3305 [INSPIRE].
L.F. Abbott, A mechanism for reducing the value of the cosmological constant, Phys. Lett. B 150 (1985) 427.
J. Garriga and A. Vilenkin, On likely values of the cosmological constant, Phys. Rev. D 61 (2000) 083502 [astro-ph/9908115] [INSPIRE].
C. Vafa and E. Witten, Parity conservation in QCD, Phys. Rev. Lett. 53 (1984) 535 [INSPIRE].
M. Lüscher, The secret long range force in quantum field theories with instantons, Phys. Lett. B 78 (1978) 465.
E. Witten, Current algebra theorems for the U(1) goldstone boson, Nucl. Phys. B 156 (1979) 269 [INSPIRE].
F.R. Urban and A.R. Zhitnitsky, The cosmological constant from the QCD Veneziano ghost, Phys. Lett. B 688 (2010) 9 [arXiv:0906.2162] [INSPIRE].
P. Petreczky, H.-P. Schadler and S. Sharma, The topological susceptibility in finite temperature QCD and axion cosmology, Phys. Lett. B 762 (2016) 498 [arXiv:1606.03145] [INSPIRE].
S. Borsányi et al., Calculation of the axion mass based on high-temperature lattice quantum chromodynamics, Nature 539 (2016) 69 [arXiv:1606.07494] [INSPIRE].
A.D. Linde, Phase transitions in gauge theories and cosmology, Rept. Prog. Phys. 42 (1979) 389 [INSPIRE].
B. Bellazzini et al., Cosmological and astrophysical probes of vacuum energy, JHEP 06 (2016) 104 [arXiv:1502.04702] [INSPIRE].
A.D. Linde, Vacuum structure in gauge theories: the problem of strong CP violation and cosmology, Phys. Lett. 93B (1980) 327.
A.D. Linde, Inflation and axion cosmology, Phys. Lett. B 201 (1988) 437 [INSPIRE].
A.D. Linde, Axions in inflationary cosmology, Phys. Lett. B 259 (1991) 38 [INSPIRE].
S. Hellerman and J. Walcher, Dark matter and the anthropic principle, Phys. Rev. D 72 (2005) 123520 [hep-th/0508161] [INSPIRE].
A. Arvanitaki et al., String axiverse, Phys. Rev. D 81 (2010) 123530 [arXiv:0905.4720] [INSPIRE].
N. Weiss, The cosmological constant and the strong CP problem, Phys. Rev. D 37 (1988) 3760 [INSPIRE].
F. Takahashi, A possible solution to the strong CP problem, Prog. Theor. Phys. 121 (2009) 711 [arXiv:0804.2478] [INSPIRE].
A. Aurilia, H. Nicolai and P.K. Townsend, Hidden constants: the theta parameter of QCD and the cosmological constant of N = 8 supergravity, Nucl. Phys. B 176 (1980) 509 [INSPIRE].
F. Wilczek, Foundations and working pictures in microphysical cosmology, Phys. Rept. 104 (1984) 143 [INSPIRE].
Open Access
This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
Author information
Authors and Affiliations
Corresponding author
Additional information
ArXiv ePrint: 1710.01740
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.
The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder.
To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Kaloper, N., Terning, J. Landscaping the strong CP problem. J. High Energ. Phys. 2019, 32 (2019). https://doi.org/10.1007/JHEP03(2019)032
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP03(2019)032