scholarly journals Photophilic hadronic axion from heavy magnetic monopoles

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Anton V. Sokolov ◽  
Andreas Ringwald
Keyword(s):  
Globular Clusters ◽  
Proper Time ◽  
Magnetic Monopoles ◽  
Horizontal Branch Stars ◽  
Hadronic Axion ◽  
The Standard Model ◽  
Leading Term ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
The Universe

Abstract We propose a model for the QCD axion which is realized through a coupling of the Peccei-Quinn scalar field to magnetically charged fermions at high energies. We show that the axion of this model solves the strong CP problem and then integrate out heavy magnetic monopoles using the Schwinger proper time method. We find that the model discussed yields axion couplings to the Standard Model which are drastically different from the ones calculated within the KSVZ/DFSZ-type models, so that large part of the corresponding parameter space can be probed by various projected experiments. Moreover, the axion we introduce is consistent with the astrophysical hints suggested both by anomalous TeV-transparency of the Universe and by excessive cooling of horizontal branch stars in globular clusters. We argue that the leading term for the cosmic axion abundance is not changed compared to the conventional pre-inflationary QCD axion case for axion decay constant fa> 1012 GeV.

scholarly journals Axiogenesis from SU(2)R phase transition

2021 ◽  
Vol 2021 (10) ◽  
Author(s):  
Keisuke Harigaya ◽  
Ruoquan Wang
Keyword(s):  
Parameter Space ◽  
Gauge Boson ◽  
Baryon Number ◽  
Mass Scale ◽  
Minimal Extension ◽  
Abelian Gauge ◽  
The Standard Model ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
The Universe

Abstract The baryon asymmetry of the universe may be explained by rotations of the QCD axion in field space and baryon number violating processes. We consider the minimal extension of the Standard Model by a non-Abelian gauge interaction, SU(2)R, whose sphaleron process violates baryon number. Assuming that axion dark matter is also created from the axion rotation by the kinetic misalignment mechanism, the mass scale of the SU(2)R gauge boson is fixed as a function of the QCD axion decay constant, and vise versa. Significant portion of the parameter space has already been excluded by new gauge boson searches, and the high-luminocity LHC will further probe the viable parameter space.

scholarly journals Challenges for an axion explanation of the muon g − 2 measurement

2021 ◽  
Vol 2021 (9) ◽  
Author(s):  
Manuel A. Buen-Abad ◽  
JiJi Fan ◽  
Matthew Reece ◽  
Chen Sun
Keyword(s):  
Decay Constant ◽  
Standard Model Prediction ◽  
New Physics ◽  
Effective Theory ◽  
General Sense ◽  
Weak Scale ◽  
Initial Application ◽  
The Standard Model ◽  
Axion Decay Constant ◽  
Axion Decay

Abstract The discrepancy between the muon g − 2 measurement and the Standard Model prediction points to new physics around or below the weak scale. It is tantalizing to consider the loop effects of a heavy axion (in the general sense, also known as an axion-like particle) coupling to leptons and photons as an explanation for this discrepancy. We provide an updated analysis of the necessary couplings, including two-loop contributions, and find that the new physics operators point to an axion decay constant on the order of 10s of GeV. This poses major problems for such an explanation, as the axion couplings to leptons and photons must be generated at low scales. We outline some possibilities for how such couplings can arise, and find that these scenarios predict new charged matter at or below the weak scale and new scalars can mix with the Higgs boson, raising numerous phenomenological challenges. These scenarios also all predict additional contributions to the muon g−2 itself, calling the initial application of the axion effective theory into question. We conclude that there is little reason to favor an axion explanation of the muon g – 2 measurement relative to other models postulating new weak-scale matter.

Searches for exotica and dark matter with neutrino telescopes

2019 ◽  
Vol 377 (2161) ◽  
pp. 20190084
Author(s):  
A. Margiotta
Keyword(s):  
Dark Matter ◽  
Cosmic Radiation ◽  
Charged Particles ◽  
New Physics ◽  
Magnetic Monopoles ◽  
Neutrino Telescopes ◽  
The Standard Model ◽  
Large Water ◽  
The Universe ◽  
Detector Volume

Neutrino telescopes are designed to search for neutrino sources in the Universe, exploiting the Cherenkov light emitted along the path of the charged particles produced in interactions occurring close to the detector volume. Their huge size and the shield offered by large water or ice overburden make them excellent tools to search for exotic and rare particles in the cosmic radiation. In particular, they are sensitive to particles not predicted by the Standard Model that could be messenger of new physics. An overview of the experimental scenario and the relevant results obtained looking for magnetic monopoles, dark matter candidates and other exotic relic particles with neutrino telescopes is given, together with the description of possible new perspectives. This article is part of a discussion meeting issue ‘Topological avatars of new physics’.

scholarly journals Precision axion physics with running axion couplings

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Kiwoon Choi ◽  
Sang Hui Im ◽  
Hee Jung Kim ◽  
Hyeonseok Seong
Keyword(s):  
Top Quark ◽  
Decay Constant ◽  
Higgs Field ◽  
Energy Scale ◽  
Low Energy ◽  
Loop Contribution ◽  
The Standard Model ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
Sizable Difference

Abstract We study the renormalization group running of axion couplings while taking into account that the Standard Model can be extended to its supersymmetric extension at a certain energy scale below the axion decay constant. We then apply our results to three different classes of axion models, i.e. KSVZ-like, DFSZ-like, and string-theoretic axions, and examine if string-theoretic axions can be distinguished from others by having a different pattern of low energy couplings to the photon, nucleons and electron. We find that the low energy couplings of string-theoretic axions have a similar pattern as those of KSVZ-like axions but yet reveal a sizable difference which might be testable in future axion search experiments. We also note that the coupling of KSVZ-like QCD axions to the electron is dominated by a three-loop contribution involving the exotic heavy quark, gluons, top quark and Higgs field.

ON THE ORIGIN OF DENSITY FLUCTUATIONS IN THE UNIVERSE

1993 ◽  
Vol 08 (14) ◽  
pp. 1285-1290 ◽  
Author(s):  
M. D. POLLOCK
Keyword(s):  
Background Radiation ◽  
Density Fluctuations ◽  
Microwave Background ◽  
Superstring Theory ◽  
Scale Invariant ◽  
Order Unity ◽  
Microwave Background Radiation ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
The Universe

It has been shown by Harrison that quantum fluctuations of the metric at the Planck era lead to a scale-invariant spectrum of density fluctuations ξ ≡ δρ/ρ at all subsequent times of the expansion of a Friedmann universe, irrespective of whether there is inflation. For the vacuum Einstein theory, ξ is of order unity, and thus is too large. But for the dimensionally reduced, heterotic superstring, ξ ≈ πfα/M P ≈ 6 × 10−4, where M P is the Planck mass and fa ≈ 2 × 10−4M P is the axion decay constant. This result is in approximate agreement with the observations of the temperature fluctuations in the cosmic microwave background radiation by COBE, δT/T ≈ 6 × 10−6, and thus constitutes evidence in favor of the superstring theory.

scholarly journals R-parity violation axiogenesis

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Raymond T. Co ◽  
Keisuke Harigaya ◽  
Zachary Johnson ◽  
Aaron Pierce
Keyword(s):  
Parity Violation ◽  
Decay Constant ◽  
Big Bang ◽  
Proton Decay ◽  
Big Bang Nucleosynthesis ◽  
Chiral Asymmetry ◽  
Axion Field ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
The Universe

Abstract We show that the rotation of the QCD axion field, aided by B−L violation from supersymmetric R-parity violating couplings, can yield the observed baryon abundance. Strong sphaleron processes transfer the angular momentum of the axion field into a quark chiral asymmetry, which R-parity violating couplings convert to the baryon asymmetry of the Universe. We focus on the case of dimensionless R-parity violating couplings with textures motivated by grand unified theories and comment on more general scenarios. The axion decay constant and mass spectrum of supersymmetric particles are constrained by Big Bang nucleosynthesis, proton decay from the R-parity violation, and successful thermalization of the Peccei-Quinn symmetry breaking field. Axion dark matter may be produced by the axion rotation via the kinetic misalignment mechanism for axion decay constants below 1010 GeV, or by the conventional misalignment mechanism for 1011-12 GeV. The viable parameter region can be probed by proton decay and axion searches. This scenario may also have connections with collider experiments, including searches for long-lived particles, and observations of gravitational waves.

scholarly journals Maximal axion misalignment from a minimal model

2020 ◽  
Vol 2020 (10) ◽  
Author(s):  
Junwu Huang ◽  
Amalia Madden ◽  
Davide Racco ◽  
Mario Reig
Keyword(s):  
Phase Transition ◽  
Dark Matter ◽  
Decay Constant ◽  
Axion Mass ◽  
Qcd Phase Transition ◽  
Axion Field ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
The Universe ◽  
Simple Dynamical Model

Abstract The QCD axion is one of the best motivated dark matter candidates. The misalignment mechanism is well known to produce an abundance of the QCD axion consistent with dark matter for an axion decay constant of order 1012 GeV. For a smaller decay constant, the QCD axion, with Peccei-Quinn symmetry broken during inflation, makes up only a fraction of dark matter unless the axion field starts oscillating very close to the top of its potential, in a scenario called “large-misalignment”. In this scenario, QCD axion dark matter with a small axion decay constant is partially comprised of very dense structures. We present a simple dynamical model realising the large-misalignment mechanism. During inflation, the axion classically rolls down its potential approaching its minimum. After inflation, the Universe reheats to a high temperature and a modulus (real scalar field) changes the sign of its minimum dynamically, which changes the sign of the mass of a vector-like fermion charged under QCD. As a result, the minimum of the axion potential during inflation becomes the maximum of the potential after the Universe has cooled through the QCD phase transition and the axion starts oscillating. In this model, we can produce QCD axion dark matter with a decay constant as low as 6 × 109 GeV and an axion mass up to 1 meV. We also summarise the phenomenological implications of this mechanism for dark matter experiments and colliders.

scholarly journals Axion–Sterile Neutrino Dark Matter

Universe ◽  
2021 ◽  
Vol 7 (10) ◽  
pp. 354
Author(s):  
Alberto Salvio ◽  
Simone Scollo
Keyword(s):  
Dark Matter ◽  
Decay Constant ◽  
Sterile Neutrino ◽  
Topological Defects ◽  
Primordial Black Holes ◽  
Neutrino Production ◽  
The Standard Model ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
Production Mechanisms

Extending the standard model with three right-handed neutrinos and a simple QCD axion sector can account for neutrino oscillations, dark matter and baryon asymmetry; at the same time, it solves the strong CP problem, stabilizes the electroweak vacuum and can implement critical Higgs inflation (satisfying all current observational bounds). We perform here a general analysis of dark matter (DM) in such a model, which we call the aνMSM. Although critical Higgs inflation features a (quasi) inflection point of the inflaton potential, we show that DM cannot receive a contribution from primordial black holes in the aνMSM. This leads to a multicomponent axion–sterile neutrino DM and allows us to relate the axion parameters, such as the axion decay constant, to the neutrino parameters. We include several DM production mechanisms: the axion production via misalignment and decay of topological defects as well as the sterile neutrino production through the resonant and non-resonant mechanisms and in the recently proposed CPT-symmetric universe.

scholarly journals Strong CP problem and axion dark matter with small instantons

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Ryuichiro Kitano ◽  
Wen Yin
Keyword(s):  
Dark Matter ◽  
Decay Constant ◽  
Strongly Coupled ◽  
Axion Mass ◽  
High Energies ◽  
Mass Correction ◽  
Large Correction ◽  
Axion Decay Constant ◽  
Axion Decay ◽  
The Universe

Abstract The axion mass receives a large correction from small instantons if the QCD gets strongly coupled at high energies. We discuss the size of the new CP violating phases caused by the fact that the small instantons are sensitive to the UV physics. We also discuss the effects of the mass correction on the axion abundance of the Universe. Taking the small-instanton contributions into account, we propose a natural scenario of axion dark matter where the axion decay constant is as large as 1015-16 GeV. The scenario works in the high-scale inflation models.

An Interview with the Physicist that Her Head in the Universe and Both Feet on the Earth

2019 ◽  
Author(s):  
Adib Rifqi Setiawan
Keyword(s):  
Standard Model ◽  
Particle Physics ◽  
Space Time ◽  
Additional Dimension ◽  
The Earth ◽  
The Standard Model ◽  
The Universe

Put simply, Lisa Randall’s job is to figure out how the universe works, and what it’s made of. Her contributions to theoretical particle physics include two models of space-time that bear her name. The first Randall–Sundrum model addressed a problem with the Standard Model of the universe, and the second concerned the possibility of a warped additional dimension of space. In this work, we caught up with Randall to talk about why she chose a career in physics, where she finds inspiration, and what advice she’d offer budding physicists. This article has been edited for clarity. My favourite quote in this interview is, “Figure out what you enjoy, what your talents are, and what you’re most curious to learn about.” If you insterest in her work, you can contact her on Twitter @lirarandall.

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