Single Workshop

Abstract

The purpose of this workshop is to bring together scientists with different backgrounds and expertise to discuss open problems, recent developments and future directions in axion physics, a field that is notoriously replete with interdisciplinary connections. The aim is to foster a fruitful cross breeding between different theoretical areas, with a focus on certain open issues in axion particle physics, astrophysics and cosmology. Quantitative assessments of the axion contribution to Cold Dark Matter (CDM) involve top-notch lattice simulations of non- perturbative QCD effects, as well as of the cosmic evolution of axionic topological defects. Astrophysical observations provide strong bounds on axion properties because stellar evolution would be affected by the existence of axions and, intriguingly, some excesses in star energy losses have been reported. Cosmological scenarios in which the PQ symmetry is broken before inflation foresee axions imprints in the CMB, while in post-inflationary scenarios axion miniclusters, with overdensities several orders of magnitude larger than the local density of CDM, are expected to form, and a reliable assessment of their properties is of utmost importance. From the experimental side, a blossoming of potentially game-changing ideas, with an exciting crossover from experimental particle physics to materials science and cutting-edge technologies is inspiring new methods for axion searches. Novel techniques have been put forth that, besides exploiting the axion- photon coupling, aim to reveal axions via their couplings to nucleons and electrons. The interaction between the experimental and theoretical communities will foster the merging of `how to search’ with `where to search’ into optimized strategies to hunt for the axion.

Topics

* Training week (1st week: April 26^(*) - 28)
* Axion astrophysics (2nd & 3rd weeks: May 2^(*) - 12)
* Axion cosmology (3rd & 4th weeks: May 8 -19)
* Axions in particle physics (4th & 5th weeks: May 15 - 26)
* Axion experiments (5th & 6th weeks: May 22 - June 1^(*))
* Conference week (7th week: June 5 - 9)

^(*) Note that April 25th, May 1st and June 2nd are days of holidays in Italy

Organizers

Gianpaolo Carosi (LLNL, carosi2@llnl.gov)
Kiwoon Choi (IBS, Daejeon, CTPU, kchoi@ibs.re.kr)
Luca Di Luzio (University of Padua and INFN - Padua, luca.diluzio@unipd.it)
Babette Döbrich (CERN, babette.dobrich@cern.ch)
Inma Domínguez (University of Granada, inma@ugr.es)
Maurizio Giannotti (Barry University, MGiannotti@barry.edu)
Igor Garcia Irastorza (University of Zaragoza, igor.irastorza@cern.ch)
Enrico Nardi (INFN - LNF, enrico.nardi@lnf.infn.it)
Andreas Ringwald (DESY, andreas.ringwald@desy.de)
Pierre Sikivie (University of Florida, sikivie@phys.ufl.edu)
Julia Vogel (LLNL & University of Zaragoza, Julia.Vogel@cern.ch)

Local organizers

Enrico Nardi (INFN - LNF)

Contact

enrico.nardi@lnf.infn.it

Website:

Related events

Axions across boundaries between Particle Physics, Astrophysics, Cosmology and forefront Detection Technologies (Training Week) - 26 Apr, 2023
Axions across boundaries between Particle Physics, Astrophysics, Cosmology and forefront Detection Technologies (Conference) - 05 Jun, 2023

Poster session

The participants who would like to present a poster are kindly invited to send an email with the title and a short abstract to alice.bernamonti@unifuit before May 22, specifying for which week of the workshop. Since a limited number of panels is available, the organizers will select the posters shortly after the deadline.

week 3

	Monday	Tuesday	Wednesday	Thursday	Friday
11:30 - 12:30		Tomasevic	Newenfeld	Collin-Ellerin	Caceres
13:00 - 14:30	lunch	lunch	lunch	lunch	lunch
14:30 - 15:30	Sorce			Emparan

Elena Caceres: 'On Sparse SYK, wormholes, and chaos"
Sean Colin-Ellerin: "Bootstrapping wuantum extremal surfaces
Roberto Emparan: "Black tsunamis and naked singularities in AdS'
Dominik Neuenfeld: "Bounds on gravitational brane couplings and tomography in AdS3 black hole microstates"
Jonathan Sorce: "Bulk causality from boundary entanglement: the connected wedge theorem revisited"
Marija Tomasevic: 'ds through holography

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Talks

Date	Speaker	Title	Type	Useful Links
02 May, 2023 - 14:00-14:30		*Participants two minutes self presentation*	Introduction
02 May, 2023 - 14:30-15:30		Canceled	Seminar
03 May, 2023 - 14:00-15:00	Oscar Straniero	Overview of axion astrophysics and perspectives from future astronomical probes	Seminar
04 May, 2023 - 11:00-12:00	Jihn E. Kim	Axions: a short historical review. Recent results on quintessential axions from a new confining force as source of Dark Energy	Seminar
04 May, 2023 - 14:00-15:00	Giuseppe Lucente & Pierluca Carenza	Progress on axions from supernovae. New production mechanism and prospects for detection	Seminar
05 May, 2023 - 14:00-15:00	Javier Redondo & Giovanni Pierobon	Axions in Cosmology	Seminar
08 May, 2023 - 14:00-14:30		*Participants two minutes self presentation*	Introduction
08 May, 2023 - 14:30-15:30	Michael Dine	Overview on axions: open problems and future directions	Seminar
09 May, 2023 - 14:00-15:00	Edward Hardy	Axion contribution from topological strings	Seminar
10 May, 2023 - 11:00-12:00	Kiwoon Choi	Discussion on hep-th/2001.07152 "Consequences of the order of the limit of infinite spacetime volume and the sum over topological sectors..."	Discussion
10 May, 2023 - 14:00-15:00	Maurizio Giannotti & Sang Hui Im	Axion physics with running axion couplings	Seminar
11 May, 2023 - 14:00-15:00	Andreas Ringwald	Electromagnetic Couplings of the Axion	Seminar
12 May, 2023 - 11:30-12:30	GGI Seminar Series: Benoit Laurent (McGill U., Montréal, Canada)	Model-indipendent bubble wall velocities in local thermal equilibrium	Seminar	Abstract Determining the bubble wall velocity during a first-order phase transition is of great importance to accurately predict the resulting gravitational wave signals and matter-antimatter asymmetry. In this talk, I will explain how this calculation can be significantly simplified when local thermal equilibrium (LTE) is maintained in the plasma. Using this LTE assumption, I will show that the scalar fields' equations of motion can be replaced by a new matching condition which can be interpreted as the conservation of entropy. The resulting system of equations can be expressed in terms of only four parameters that completely characterize a particle physics model. I will present an efficient algorithm to solve these equations and discuss the properties of their solutions. Even when the LTE assumption is badly violated, these solutions can still be helpful as they provide an upper bound on the wall velocity. Finally, I will compute the kinetic energy fraction which is essential for predicting the gravitational wave spectrum produced during the phase transition.
12 May, 2023 - 14:00-15:00	Malte Buschmann & Joshua Foster	Overview of axions and Neutron Stars	Seminar
15 May, 2023 - 12:00-12:40	Marco Gorghetto	Formation of Ultralight Dark Matter Solar Halos	Talk	Abstract As yet undiscovered light bosons may constitute all or part of the dark matter (DM) of our Universe, and are expected to have (weak) self-interactions. We show that quartic self-interactions generically induce the capture of dark matter from the surrounding halo by external gravitational potentials such as those of stars, including the Sun. This leads to the subsequent formation of dark matter bound states supported by such external potentials, resembling gravitational atoms (e.g. a solar halo around our own Sun). Their growth is governed by the ratio ξfoc = λdB/R⋆ between the de Broglie wavelength of the incoming DM waves, λdB, and the radius of the ground state R⋆. For ξfoc ≲ 1, the gravitational atom grows to a steady state that balances the capture of particles and the inverse, stripping, process. For ξfoc ≳ 1, a significant gravitational-focusing effect leads to exponential accumulation of mass from the galactic DM halo into the atom. For instance, a dark matter axion with mass of the order of 10^{−14} eV and decay constant between 10^7 and 10^8 GeV would lead to formation of a dense halo, with local DM density at the position of the Earth O(10^4) times larger than that predicted by the standard halo model. For attractive self-interactions, after the formation, the gravitational atom is destabilized at a large density, leading to collapse accompanied by emission of relativistic bosons (‘Bosenova’) on a timescale that can be comparable to the lifetime of the Solar System.
15 May, 2023 - 14:00-14:30		*Participants two minutes self presentation*	Introduction
15 May, 2023 - 14:30-15:30	Gia Dvali	Strong CP and axions in the dual formulation	Seminar
16 May, 2023 - 14:00-15:00	Giovanni Villadoro	Thermal axion production in the Early Universe	Seminar
17 May, 2023 - 11:00-12:00	Gia Dvali	One more discussion on hep-th/2001.07152 "Consequences of the order of the limit of infinite spacetime volume and the sum over topological sectors..."	Discussion
17 May, 2023 - 14:00-15:00	Robert Ziegler	Axions and flavour	Seminar
18 May, 2023 - 14:00-15:00	Wei Xue	Boson stars	Seminar
19 May, 2023 - 12:00-12:40	Philip Soerensen	Axion Kinetic Misalignment - What is it, what does it do, and how do you get it?	Talk	Abstract Axion kinetic misalignment is a mechanism that may enhance the dark matter relic found in models of QCD axions or axion-like-particles by considering initial conditions with large kinetic energy. This is interesting because it motivates axion dark matter at lower decay constants where the couplings to matter, incl. detectors, are stronger. As my contribution to this wonderful workshop, I will here give an introduction to this mechanism. I will discuss some of the phenomenology that arises from kinetic misalignment and I will also briefly discuss my recent work on how the mechanism can be realized.
19 May, 2023 - 14:00-15:00	Nicholas Rodd	The axion background	Seminar
22 May, 2023 - 14:00-14:30		*Participants two minutes self presentation*	Introduction
22 May, 2023 - 14:30-15:30	Elisa Todarello	The Echo Method for Axion Dark Matter Detection	Seminar
23 May, 2023 - 12:00-12:40	Mario Reig Lopez	Axion couplings in Grand Unified Theories	Talk	Abstract In this talk (based on 2206.07053) I discuss axion couplings to gauge bosons in Grand Unified Theories, where the Standard Model is embedded in a simple 4D gauge group. The topological nature of these couplings allows them to be matched from the UV to the IR, and the ratio of the anomaly with photons and gluons for any axion is fixed by unification. I will show that this implies that there is a single axion, the QCD axion, with an anomalous coupling to photons. Other light axion-like particles can couple to photons by mixing through the QCD axion portal and lie to the right of the QCD line prediction in the mass-coupling plane. Axions which break the unification relation between gluon and photon couplings are necessarily charged under the GUT gauge group and become heavy from perturbative mass contributions. As a result, a discovery of an axion to the left of the QCD line can rule out simple Grand Unified Theories.
23 May, 2023 - 14:00-15:00	Zurab Berezhiani	Axions and where to find them.... New elements for the identikit	Seminar
24 May, 2023 - 12:00-12:40	Pablo Quilez	Multiple QCD axions	Talk	Abstract How many QCD axions can there be? Can the standard ma-fa relation be modified without extra sources of PQ breaking? We will study in detail the possible masses and couplings to the nEDM of a multiple axion system. A novel sum rule linking multiple axion signals will be obtained and rigorously proved solely as a consequence of the PQ symmetry.
24 May, 2023 - 14:00-15:00	Pierre Sikivie	How observations may tell axions and WIMPs apart	Seminar
25 May, 2023 - 14:00-15:00	Hyungjin Kim	Wave dark matter	Seminar
26 May, 2023 - 12:00-12:40	Nick Houston	Nuclear decay anomalies as a signature of axion dark matter	Talk	Abstract A number of nuclear decay anomalies have been reported in the literature, which purport to show periodic variations in the decay rates of certain radioisotopes. If these reports reflect reality, they would necessitate a seismic shift in our understanding of fundamental physics. We provide the first mechanism to explain these findings, via the misalignment mechanism of QCD axion dark matter, wherein oscillations of the effective theta angle induce periodic variation in nuclear binding energies and hence decay rates. Expecting this effect to be most pronounced in low-Q systems, we analyse 12 years of tritium decay data (Q ≃ 18.6 keV) taken at the European Commission’s Joint Research Centre. Finding no statistically significant excess, we then place novel constraints on the corresponding axion parameter space.
26 May, 2023 - 14:00-15:00	Junwu Huang	Topological defects of light bosons	Seminar
29 May, 2023 - 12:00-12:40	Rustam Balafendiev	Wire Metamaterials for Axion Search: ALPHA	Talk	Abstract Wire metamaterials have long been a subject of scientific inquiry due to their properties as artificial plasma materials. With the plasma frequency exclusively determined by the geometrical parameters of period and radius, a number of applications have been proposed in a large range of frequencies spanning from hundreds MHz to THz. Recently, wire metamaterials have found a new application in the proposed detectors of axion dark matter. Thanks to their plasma-like behavior when operating near plasma frequency wire metamaterials can be used as a low-loss ENZ materials, allowing for construction of large microwave cavities with a fundamental frequency on the order of tens of GHz. In this talk I will give a short introduction to wire metamaterials and ALPHA collaboration’s aim of implementing them in plasma haloscopes.
29 May, 2023 - 14:00-14:30		*Participants two minutes self presentation*	Introduction
29 May, 2023 - 14:30-15:30	Gianpaolo Carosi	Overview of experimental searches for Axion Dark Matter	Seminar
30 May, 2023 - 12:00-12:40	Katherine Fraser	Axion Mass from Magnetic Monopole Loops	Talk	Abstract We show that axions interacting with abelian gauge fields obtain a potential from loops of magnetic monopoles. This is a consequence of the Witten effect: the axion field causes the monopoles to acquire an electric charge and alters their energy spectrum. The axion potential can also be understood as a type of instanton effect due to a Euclidean monopole worldline winding around its dyon collective coordinate. We calculate this effect, which has features in common with both nonabelian instantons and Euclidean brane instantons. To provide consistency checks, we argue that this axion potential vanishes in the presence of a massless charged fermion and that it is robust against the presence of higher-derivative corrections in the effective Lagrangian. Finally, as a first step toward connecting with particle phenomenology and cosmology, we discuss the regime in which this potential is important in determining the dark matter relic abundance in a hidden sector containing an abelian gauge group, monopoles, and axions.
30 May, 2023 - 14:00-15:00	Esther Ferrer-Ribas	Detector development for solar axion searches	Seminar
31 May, 2023 - 14:00-15:00	Andrew Geraci	Status of the ARIADNE experiment and its challenges	Seminar
01 Jun, 2023 - 12:00-12:40	Cristina Margalejo Blasco	Data taking and analysis with the IAXO pathfinder system	Talk
01 Jun, 2023 - 14:00-15:00	Amalia Madden	The Piezoaxionic Effect	Seminar	Abstract In this talk I will demonstrate how the spontaneous violation of parity within piezoelectric materials can induce several new experimental observables for the QCD axion via their fundamental coupling to gluons. The first effect, termed "the piezoaxionic effect", involves the generation of an oscillating mechanical stress within a piezoelectric crystal due to the presence of QCD axion dark matter. Our proposed experimental setup could probe this effect for axion masses between 10^-11 eV and 10^-7 eV. The second effect, termed "the ferroaxionic effect", involves a QCD axion-mediated force that can be sourced by a piezoelectric crystal. This force can be detected via nuclear magnetic resonance and has sensitivity to axion masses between 10^-5 eV and 10^-2 eV. Together, these new observables could be used in the near future to probe two challenging mass ranges for most axion detection concepts.

Axions across boundaries between Particle Physics, Astrophysics, Cosmology and forefront Detection Technologies