# Topology in QCD and the axion abundance

@article{Kitano2015TopologyIQ, title={Topology in QCD and the axion abundance}, author={Ryuichiro Kitano and Norikazu Yamada}, journal={Journal of High Energy Physics}, year={2015}, volume={2015}, pages={1-16} }

A bstractThe temperature dependence of the topological susceptibility in QCD, χt, essentially determines the abundance of the QCD axion in the Universe, and is commonly estimated, based on the instanton picture, to be a certain negative power of temperature. While lattice QCD should be able to check this behavior in principle, the temperature range where lattice QCD works is rather limited in practice, because the topological charge is apt to freezes at high temperatures. In this work, two…

## 34 Citations

Topology in full QCD at high temperature: a multicanonical approach

- PhysicsJournal of High Energy Physics
- 2018

A bstractWe investigate the topological properties of Nf = 2 + 1 QCD with physical quark masses, at temperatures around 500 MeV. With the aim of obtaining a reliable sampling of topological modes in…

Topological susceptibility at high temperature on the lattice

- Physics
- 2016

A bstractQCD topological susceptibility at high temperature, χt(T ), provides an important input for the estimate of the axion abundance in the present Universe. While the model independent…

Axion phenomenology and θ-dependence from Nf = 2 + 1 lattice QCD

- Physics
- 2015

A bstractWe investigate the topological properties of Nf = 2 + 1 QCD with physical quark masses, both at zero and finite temperature. We adopt stout improved staggered fermions and explore a range of…

Axions, Instantons, and the Lattice

- Physics
- 2017

If the QCD axion is a significant component of dark matter, and if the universe was once hotter than a few hundred MeV, the axion relic abundance depends on the function $\chi(T)$, the…

Recent progress on QCD inputs for axion phenomenology

- Physics
- 2017

The properties of the QCD axion are strictly related to the dependence of strong interactions on the topological parameter theta. We present a determination of the topological properties of QCD for…

Confronting the instanton calculus in Yang-Mills theories to the lattice

- Physics
- 2017

The Standard Model (SM) in the elementary particle physics describes the fundamental physical law in nature and, in principle, provides us infinitely accurate predictions,
which are consistent with…

The semi-classical approximation at high temperature revisited

- MathematicsJournal of High Energy Physics
- 2020

We revisit the semi-classical calculation of the size distribution of instantons at finite temperature in non-abelian gauge theories in four dimensions. The relevant functional determinants were…

## References

SHOWING 1-10 OF 84 REFERENCES

Lattice QCD input for axion cosmology

- Physics
- 2015

One intriguing BSM particle is the QCD axion, which could simultaneously provide a solution to the Strong CP problem and account for some, if not all, of the dark matter density in the universe. This…

Instanton content of finite temperature QCD matter.

- PhysicsPhysical review. D, Particles and fields
- 1995

A suppression of the topological susceptibility at finite temperature is found, agreeing with the PCAC bounds at low temperature and enhanced suppression for temperatures at and above the deconfinement transition.

End point of a first-order phase transition in many-flavor lattice QCD at finite temperature and density.

- PhysicsPhysical review letters
- 2013

This work investigates the phase structure of (2+N(f))-flavor QCD, where the mass of two flavors is fixed to a small value and the others are heavy, and determines the critical mass of heavy flavors separating the first-order and crossover regions and finds it to become larger with N(f).

Topology across the finite temperature transition studied by overimproved cooling in gluodynamics and QCD

- Physics
- 2013

Gluodynamics and two-flavor QCD at non-zero temperature are studied with the so-called overimproved cooling technique under which caloron solutions may remain stable. We consider topological…

Instanton Effects in Three Flavor QCD

- Physics
- 2015

Recently it was shown that in QCD-like theories with Nf > N, where Nf is the number of light avors and N is the number of colors, there are correlation functions that vanish in perturbation theory…

Finite temperature study of the axial U(1) symmetry on the lattice with overlap fermion formulation

- Physics
- 2013

We examine the axial U(1) symmetry near and above the finite temperature phase transition in two-flavor QCD using lattice QCD simulations. Although the axial U(1) symmetry is always violated by…

Axion cosmology revisited

- Physics
- 2010

The misalignment mechanism for axion production depends on the temperature-dependent axion mass. The latter has recently been determined within the interacting instanton liquid model, and provides…

QCD phase transition with chiral quarks and physical quark masses.

- PhysicsPhysical review letters
- 2014

The first lattice calculation of the QCD phase transition using chiral fermions with physical quark masses using 2+1 quark flavors, spatial volumes between (4 fm) and (11 fm)(3) and temperatures between 139 and 196 MeV finds no metastability near the peak and a peak height which does not change when a 5 fm spatial extent is increased to 10 fm.