We highlight that the observed concurrence between the baryon and dark matter relic densities can be explained via a parametric coincidence between two distinct production mechanisms: Affleck-Dine baryogenesis and dark matter UV freeze-in. In the Affleck-Dine mechanism, the baryon asymmetry is naturally proportional to the inflationary reheating temperature <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>rh</mi></mrow></msub></math>, which also plays a critical role in setting the relic abundance of UV freeze-in dark matter. Since Affleck-Dine baryogenesis requires flat directions in the potential, the framework is inherently supersymmetric, offering compelling UV freeze-in dark matter candidates such as the gravitino. We outline scenarios in which <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>rh</mi></mrow></msub></math> simultaneously determines both relic abundances, resulting in a baryon-to-dark matter ratio of order unity that is largely insensitive to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><msub><mi>T</mi><mrow><mi>rh</mi></mrow></msub></math>. We also discuss the conditions required to avoid Q-ball formation or dark matter production by other mechanisms, such as next-to-lightest supersymmetric particle decays, to preserve the parametric coincidence between baryon and dark matter abundances.

United States

Jae Hyeok Chang

South Korea

Chang Sub Shin

James Unwin

Parametric coincidence in the baryon to dark matter ratio from Affleck-Dine baryogenesis and UV freeze-in dark matter

We report the results of a QCD axion dark matter search with discovery ability for Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) axions using an axion haloscope. Sub-Kelvin noise temperatures are reached with an ultralow noise Josephson parametric amplifier cooled by a dilution refrigerator. This work excludes (with a 90% confidence level) DFSZ axions with masses between 3.27 to <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3.34</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></mrow></math>, assuming a standard halo model with a local energy density of <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>0.45</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">G</mi><mi mathvariant="normal">e</mi><mi mathvariant="normal">V</mi><mo mathvariant="normal">/</mo><msup><mrow><mi>cm</mi></mrow><mrow><mn>3</mn></mrow></msup></mrow></math> made up 100% of axions.

C. Goodman

M. Guzzetti

C. Hanretty

L.J. Rosenberg

G. Rybka

J. Sinnis

D. Zhang

John Clarke

I. Siddiqi

A.S. Chou

M. Hollister

S. Knirck

A. Sonnenschein

T.J. Caligiure

J.R. Gleason

A.T. Hipp

P. Sikivie

M.E. Solano

N.S. Sullivan

D.B. Tanner

R. Khatiwada

G. Carosi

C. Cisneros

N. Du

N. Robertson

N. Woollett

L.D. Duffy

C. Boutan

T. Braine

E. Lentz

N.S. Oblath

M.S. Taubman

United Kingdom

E.J. Daw

C. Mostyn

M.G. Perry

C. Bartram

T.A. Dyson

S. Ruppert

M.O. Withers

C.L. Kuo

Australia

B.T. McAllister

J.H. Buckley

C. Gaikwad

J. Hoffman

K. Murch

M. Goryachev

E. Hartman

A. Quiskamp

M.E. Tobar

ADMX Axion Dark Matter Bounds around <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mrow><mn>3.3</mn><mtext> </mtext><mtext> </mtext><mi mathvariant="normal">μ</mi><mi>eV</mi></mrow></math> with Dine-Fischler-Srednicki-Zhitnitsky Discovery Ability

We show that, in the Nelson-Barr solution to the strong <math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><mi>C</mi><mi>P</mi></math>-problem, a naturally light scalar can arise. It gives rise to a completely new phenomenology beyond that of the celebrated QCD axion, if this field constitutes dark matter, as the elements of the Cabibbo–Kobayashi–Maskawa matrix vary periodically in time. We also discuss how the model can be tested using quantum sensors, in particular using nuclear clocks, which leads to an interesting synergy between different frontiers of physics.

Michael Dine

Israel

Gilad Perez

Wolfram Ratzinger

Inbar Savoray

Nelson-Barr ultralight dark matter

We consider some aspects of the Transplanckian Censorship Conjecture (TCC), which states that for theories of quantum gravity there is a limit on the lifetime of dS or quintessence states not too different than the current Hubble horizon. If one accepts the de Sitter Swampland conjecture, then the former are ruled out. We consider some aspects of tunneling to an isolated ground state in the presence of time-varying fields, in quantum mechanics and quantum field theory in the absence of gravitation, and note that lifetimes are typically enormous; in fact, there is often a finite probability for the system to remain eternally in its original state. With gravity in a universe with superluminal expansion, while the field evolution may be slowed, Planck scale fluctuations would seem likely to grow to superhorizon size long before the universe decays. We argue that the TCC, if it is correct, requires that superluminal expansion occur only for a brief period in the history of the universe, and will be followed by a p = ρ phase.

Yan Yu

Comments on the Transplanckian Censorship Conjecture

We systematically calculate the axion-photon coupling for nonminimal Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) models. Thereby, we can classify every calculated model and study the resulting distributions, relevant for axion experiments like haloscopes, helioscopes, or light-shining-through-a-wall experiments. By adding more than one additional Higgs doublet, these nonminimal DFSZ models extend the viable axion parameter space and lead to a large range of axion-photon couplings. We find couplings almost 3 orders of magnitude larger than the ones of the minimal models. Most of the possible axion-photon couplings, however, lie in the vicinity of the values dictated by the minimal models. We quantify this by introducing a theoretical prior probability distribution for DFSZ-type axions and giving 68% and 95% lower bounds as well as two-sided bands. We compare our results for the DFSZ axion-photon coupling distributions with the Kim-Shifman-Vainshtein-Zakharov case, for which a similar analysis has been conducted. Both display similar values as well as a very specific pattern. In order to identify preferred models, we discuss the role of flavor changing neutral currents and the domain wall problem as possible selection criteria. It is possible to construct a large number of nonminimal DFSZ models with a domain wall number of unity, thereby avoiding the domain wall problem. This subset also has a significantly enhanced axion-photon coupling compared to the minimal DFSZ models.

Germany

Johannes Diehl

Emmanouil Koutsangelas

Dine-Fischler-Srednicki-Zhitnitsky-type axions and where to find them

It has been known for some time that the cosmological bound on the invisible axion scale can be avoided by an early phase of strong QCD. While most approaches rely on theories where the strong coupling constant is determined through the expectation value of some scalar field, we show that this mechanism can also be implemented into the benchmark Kim-Shifman-Vainshtein-Zakharov and Dine-Fischler-Srednicki-Zhitnitsky models when the early phase of strong QCD emerges by the modification of the running coupling during inflation. For both models the physics that are responsible for making QCD strong do not displace the axions minimum by too much, so that the efficiency of the relaxation is controlled by parameters of the theory and the number of inflationary <math><mi>e</mi></math>-folds. In particular, we consider the case of very efficient relaxation where the axion abundance is dominated by inflationary quantum and postinflationary thermal fluctuations. Within this situation we identify the parameter space compatible with all cosmological constrains and derive conditions on the reheating temperature and the QCD scale during inflation that result in the axion making up all the dark matter. Because of duality below the Peccei-Quinn scale and a minor influence of the Kim-Shifman-Vainshtein-Zakharov and Dine-Fischler-Srednicki-Zhitnitsky fields on the running, our findings also apply to a minimal two-form implementation of the axion.

Removing the cosmological bound on the axion scale in the Kim-Shifman-Vainshtein-Zakharov and Dine-Fischler-Srednicki-Zhitnitsky models

We propose a mechanism for cogenesis of baryon and dark matter (DM) in the universe via the Affleck-Dine (AD) route. An AD field which breaks the lepton number symmetry, leads to the generation of lepton asymmetry by virtue of its cosmic evolution, which then gets transferred into lepton and dark sectors. While the lepton asymmetry gets converted into baryon asymmetry via sphalerons, the dark sector asymmetry leads to the final DM abundance with the symmetric part being annihilated away due to resonantly enhanced annihilation, which we choose to be provided by a gauged B − L portal. Stringent constraints from DM direct detection forces DM and B − L gauge boson masses to be light, in the few GeV ballpark. While a large portion of the model parameter space is already ruled out, the remaining parameter space is within sensitivity of laboratory as well as cosmology based experiments. The AD field also plays the role of inflaton with the required dynamics by virtue of its non-minimal coupling to gravity, consistent with observations.

India

Debasish Borah

Suruj Das

Nobuchika Okada

Affleck-Dine cogenesis of baryon and dark matter

We report an axion dark matter search at Dine-Fischler-Srednicki-Zhitnitskii sensitivity with the CAPP-12TB haloscope, assuming axions contribute 100% of the local dark matter density. The search excluded the axion-photon coupling <math><msub><mi>g</mi><mrow><mi>a</mi><mi>γ</mi><mi>γ</mi></mrow></msub></math> down to about <math><mn>6.2</mn><mo>×</mo><msup><mn>10</mn><mrow><mo>−</mo><mn>16</mn></mrow></msup><mtext> </mtext><mtext> </mtext><mrow><msup><mrow><mi>GeV</mi></mrow><mrow><mo>−</mo><mn>1</mn></mrow></msup></mrow></math> over the axion mass range between 4.51 and <math><mrow><mn>4.59</mn><mtext> </mtext><mtext> </mtext><mi>μ</mi><mi>eV</mi></mrow></math> at a 90% confidence level. The achieved experimental sensitivity can also exclude Kim-Shifman-Vainshtein-Zakharov axion dark matter that makes up just 13% of the local dark matter density. The CAPP-12TB haloscope will continue the search over a wide range of axion masses.

Andrew K. Yi

Saebyeok Ahn

Çağlar Kutlu

JinMyeong Kim

Byeong Rok Ko

Boris I. Ivanov

HeeSu Byun

Japan

Arjan F. van Loo

SeongTae Park

Junu Jeong

Ohjoon Kwon

Yasunobu Nakamura

Sergey V. Uchaikin

Jihoon Choi

Soohyung Lee

MyeongJae Lee

Yun Chang Shin

Jinsu Kim

Doyu Lee

Danho Ahn

SungJae Bae

Jiwon Lee

Younggeun Kim

Violeta Gkika

Ki Woong Lee

Seonjeong Oh

Taehyeon Seong

DongMin Kim

Woohyun Chung

Andrei Matlashov

SungWoo Youn

Yannis K. Semertzidis

Axion Dark Matter Search around <math><mrow><mn>4.55</mn><mtext> </mtext><mtext> </mtext><mi>μ</mi><mi>eV</mi></mrow></math> with Dine-Fischler-Srednicki-Zhitnitskii Sensitivity

We present a unified model that solves four major problems of the standard model, i.e., neutrino masses, origin of matter, the strong <math><mi>C</mi><mi>P</mi></math> problem and dark matter using the framework of the Affleck-Dine (AD) mechanism. The AD field is responsible for inflation, origin of matter, and neutrino masses which arise at the one loop level. Neutrino masses are therefore intimately connected to the baryon-to-photon ratio of the Universe. The dark matter in the model is the axion field used to solve the strong <math><mi>C</mi><mi>P</mi></math> problem. The model has a near massless Majorana fermion which contributes to <math><mi>Δ</mi><msub><mi>N</mi><mi>eff</mi></msub><mo>∼</mo><mn>0.1</mn></math> in the early Universe that can be tested in the upcoming CMB-S4 experiment.

Rabindra N. Mohapatra

Affleck-Dine leptogenesis with one loop neutrino masses and a solution to the strong <math><mi>C</mi><mi>P</mi></math> problem

We study charge-swapping Q-balls, a kind of composite Q-ball where positive and negative charges co-exist and swap with time, in models with a logarithmic potential that arises naturally in supersymmetric extensions of the Standard Model. We show that charge-swapping Q-balls can be copiously generated in the Affleck-Dine fragmentation process in the early universe. We find that the charge-swapping Q-balls with the logarithmic potential are extremely stable. By performing long time, parallelized lattice simulations with absorbing boundary conditions, we find that the lifetimes of such objects with low multipoles are at least 4.6 × 105/m in 3+1D and 2.5 × 107/m in 2+1D, where m is the mass scale of the scalar field. We also chart the attractor basin of the initial conditions to form these charge-swapping Q-balls.

China

Si-Yuan Hou

Paul Saffin

Qi-Xin Xie

Shuang-Yong Zhou

Charge-swapping Q-balls in a logarithmic potential and Affleck-Dine condensate fragmentation