Measurement of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msup><mml:mi>K</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mo>→</mml:mo><mml:msup><mml:mi>π</mml:mi><mml:mo>+</mml:mo></mml:msup><mml:mi>ν</mml:mi><mml:mover accent="true"><mml:mi>ν</mml:mi><mml:mo>¯</mml:mo></mml:mover></mml:math>branching ratio

We propose a minimal extension of the standard model which includes only one additional complex scalar field, flavon, with flavor-dependent global U(1) symmetry. It not only explains the hierarchical flavor structure in the quark and lepton sector (including neutrino sector), but also solves the strong CP problem by identifying the CP-odd component of the flavon as the QCD axion, which we call flaxion. Furthermore, the flaxion model solves the cosmological puzzles in the standard model, i.e., origin of dark matter, baryon asymmetry of the universe, and inflation. We show that the radial component of the flavon can play the role of inflaton without isocurvature nor domain wall problems. The dark matter abundance can be explained by the flaxion coherent oscillation, while the baryon asymmetry of the universe is generated through leptogenesis.

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“…Comparing with the current experimental bound, Br(K + → π + a) 7.3 × 10 −11 [44], the bound on f a is given by…”

Section: Constraints On Flaxionmentioning

confidence: 66%

Flaxion: a minimal extension to solve puzzles in the standard model

Ema

Hamaguchi

Moroi

et al. 2017

J. High Energ. Phys.

191

197

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“…A different approach for the study of the ultra-rare K → π νν decay and the search for lepton-flavor violating transitions was taken by the E787 [194][195][196] and E949 [197] experiments at the Alternating Gradient Synchrotron (AGS) of the Brookhaven National Laboratory. Charged Kaons were produced by 24 GeV protons interacting on a fixed target.…”

Section: Kaon Experimentsmentioning

confidence: 99%

Flavor physics in the quark sector

et al. 2010

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In the past decade, one of the major challenges of particle physics has been to gain an in-depth understanding of the role of quark flavor. In this time frame, measurements and the theoretical interpretation of their results have advanced tremendously. A much broader understanding of flavor particles has been achieved; apart from their masses and quantum numbers, there now exist detailed measurements of the characteristics of their interactions allowing stringent tests of Standard Model predictions. Among the most interesting phenomena of flavor physics is the violation of the CP symmetry that has been subtle and difficult to explore. In the past, observations of CP violation were confined to neutral K mesons, but since the early 1990s, a large number of CP-violating processes have been studied in detail in neutral B mesons. In parallel, measurements of the couplings of the heavy quarks and the dynamics for their decays in large samples of K, D, and B mesons have been greatly improved in accuracy and the results are being used as probes in the search for deviations from the Standard Model. In the near future, there will be a transition from the current to a new generation of experiments; thus a review of the status of quark flavor physics is timely. This report is the result of the work of physicists attending the 5th CKM workshop, hosted by the University of Rome "La Sapienza", September 9-13, 2008. It summarizes the results of the current generation of experiments that are about to be completed and it confronts these results with the theoretical understanding of the field which has greatly improved in the past decade. (C) 2010 Elsevier B.V. All rights reserved

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“…For masses below ∼ 0.2 GeV, the most relevant observable is K + → π + + a, whose branching ratio undergoes to the following limit [132]:…”

Section: Jhep10(2017)168mentioning

confidence: 99%

The minimal flavour violating axion

Arias-Aragón

Merlo

2017

J. High Energ. Phys.

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The solution to the Strong CP problem is analysed within the Minimal Flavour Violation (MFV) context. An Abelian factor of the complete flavour symmetry of the fermionic kinetic terms may play the role of the Peccei-Quinn symmetry in traditional axion models. Its spontaneous breaking, due to the addition of a complex scalar field to the Standard Model scalar spectrum, generates the MFV axion, which may redefine away the QCD theta parameter. It differs from the traditional QCD axion for its couplings that are governed by the fermion charges under the axial Abelian symmetry. It is also distinct from the so-called Axiflavon, as the MFV axion does not describe flavour violation, while it does induce flavour non-universality effects. The MFV axion phenomenology is discussed considering astrophysical, collider and flavour data.

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Measurement of theK+→π+νν¯branching ratio

Cited by 99 publications

References 87 publications

Flaxion: a minimal extension to solve puzzles in the standard model

Flaxion: a minimal extension to solve puzzles in the standard model

Flavor physics in the quark sector

The minimal flavour violating axion

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