I give an overview of recent developments in the study of the coupling of the QCD axion to nucleons and other octet baryons. I demonstrate how axions can be included into heavy baryon chiral perturbation theory, and present recent numerical results for the several axion-baryon couplings in SU(2) and SU(3) chiral perturbation theory for the Kim--Shifman--Vainstein--Zakharov (KSVZ) and the Dine--Fischler--Srednicki--Zhitnitsky (DFSZ) axion model.
In the past, the axion-nucleon coupling has been calculated in the framework of SU(2) heavy baryon chiral perturbation theory up to third order in the chiral power counting. Here, we extend these earlier studies to the case of heavy baryon chiral perturbation theory with SU(3) flavor symmetry and derive the axion coupling to the full SU(3) baryon octet, showing that the axion also significantly couples to hyperons. As studies on dense nuclear matter suggest the possible existence of hyperons in stellar objects such as neutron stars, our results should have phenomenological implications related…
We present a consistent implementation of weak decays involving an axion or axion-like particle in the context of an effective chiral Lagrangian. We argue that previous treatments of such processes have used an incorrect representation of the flavor-changing quark currents in the chiral theory. As an application, we derive model-independent results for the decays $K^-\toπ^- a$ and $π^-\to e^-\barν_e a$ at leading order in the chiral expansion and for arbitrary axion couplings and mass. In particular, we find that the $K^-\toπ^- a$ branching ratio is almost 40 times larger than previously estim…
Dark Matter and Baryon Asymmetry from Monopole-Axion Interactions
Indiana University（印第安纳大学）；University of Chicago（芝加哥大学）；The University of Tokyo（东京大学）；Fermi National Accelerator Laboratory（费米国家加速器实验室）；Boston University（波士顿大学）；Harvard University（哈佛大学）
The axion particle may or may not exist, but the axion field can be used, as shown here, in an explicitly local formulation of a chiral U(1) gauge theory with both classical and quantum gauge invariance. Nonabelian analogues of axion fields, which have recently been introduced, can be used, together with their special symmetries, in a similar construction of nonabelian chiral gauge theories. As in known cases, the gauge symmetry is broken and the gauge boson acquires a mass by swallowing the axions which are therefore not physical in this construction.
Because the Peccei-Quinn (PQ) symmetry has to be anomalous to solve the strong CP puzzle, some colored and chiral fermions have to transform non-trivially under this symmetry. But when the SM fermions are charged, as in the PQ or DFSZ models, this symmetry ends up entangled with the SM global symmetries, baryon (B) and lepton (L) numbers. This raises several questions addressed in this paper. First, the compatibility of axion models with some explicit B and/or L violating effects is analyzed, including those arising from seesaw mechanisms, electroweak instanton interactions, or explicit B and …
We estimate the axion properties i.e. its mass, topological susceptibility and the self-coupling within the framework of Polyakov loop enhanced Nambu-Jona-Lasinio (PNJL) model at finite temperature and quark chemical potential. PNJL model, where quarks couple simultaneously to the chiral condensate and to a background temporal quantum chromodynamics (QCD) gauge field, includes two important features of QCD phase transition, i.e. deconfinement and chiral symmetry restoration. The Polyakov loop in PNJL model plays an important role near the critical temperature. We have shown significant differe…
Probing Axion Dark Matter via the Chiral Magnetic Effect in Zero-Bias Weyl Semimetals
Centre for High Energy Physics, Indian Institute of Science（印度科学学院高能物理中心）；Department of Physics, Indian Institute of Technology Kharagpur（印度理工学院卡拉格普尔分校物理系）
We show that the commonly adopted hot dark matter (HDM) bound on the axion mass $m_a \lesssim$ 1 eV is not reliable, since it is obtained by extrapolating the chiral expansion in a region where the effective field theory breaks down. This is explicitly shown via the calculation of the axion-pion thermalization rate at the next-to-leading order in chiral perturbation theory. We finally advocate a strategy for a sound extraction of the axion HDM bound via lattice QCD techniques.
本文系统地将η '引入重子手征微扰理论。本文用导数展开的方法，给出了描述最低位重子八重态与Goldstone玻色子八重态和η '相互作用的最广义相对论有效拉格朗日量的线性阶，并得到了它的重子极限。作为明确的例子，我们计算的重子质量和π N σ-长期到一个循环的顺序在重子配方。介子质量的系统膨胀是可能的，出现的发散是重整化的。
Chiral Gravitational Wave Background from Audible Axion via Nieh-Yan Term
National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences（中国科学院大学杭州高等研究院基础物理与数学学院）；School of Astronomy and Space Science, University of Chinese Academy of Sciences（中国科学院大学天文学与空间科学学院）；Van Swinderen Institute for Particle Physics and Gravity, University of Groningen（格罗宁根大学范斯温德恩粒子物理与引力研究所）；International Center for Theoretical Physics Asia-Pacific (ICTP-AP), University of Chinese Academy of Sciences（中国科学院大学国际理论物理中心亚太地区）；Taiji Laboratory for Gravitational Wave Universe (Beijing/Hangzhou), University of Chinese Academy of Sciences（中国科学院大学太极引力波宇宙实验室（北京/杭州））；CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所理论物理重点实验室）
Baryon number is an accidental symmetry in the standard model, while Peccei-Quinn symmetry is hypothetical symmetry which is introduced to solve the strong CP problem. We study the possible connections between Peccei-Quinn symmetry and baryon number symmetry. In this framework, an axion is identified as the Nambu-Goldstone boson of baryon number violation. As a result, characteristic baryon number violating processes are predicted. We developed the general method to determine the baryon number and lepton number of new scalar in the axion model.
