arXiv subjects

Dan Kondo

Publications and source records attributed to Dan Kondo.

12 recordsLinked to original sources

arXiv2025

Multiple Axions Save High-Scale Inflation

Many models of dark matter QCD axion requires inflation at a scale $H_{\text{inf}} \lesssim 10^{6}$~GeV and hence does not allow for a detectable tensor mode fluctuation. This is because the domain wall problem forces the Peccei--Quinn symmetry to be broken during the inflation and the axions to be produced by the misalignment mechanism. We point out that theories with multiple axions can evade this constraint and allow for a high-scale inflation with detectable tensor mode. It only requires a condition on the anomaly coefficients so that there is a unique minimum for the axion potential without a fine-tuning or small parameters.

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arXiv2025

Near-SUSY to Non-SUSY Crossover

Gauge theories can be solved exactly slightly away from the supersymmetric (SUSY) limit softly broken by anomaly mediation when the size of SUSY breaking is much smaller than the dynamical scale ($m \ll \Lambda$). We show empirical evidence that the near-SUSY limit is continuously connected to the non-SUSY limit ($m \gg \Lambda$) in $\mathrm{SU}(N_c)$ gauge theories with $N_f$ quarks in the fundamental representation. The evidence includes the behavior of quark bi-linear condensate and gluon condensates, light hadron spectra, and consistency with the large $N_c$ limit. In addition, we present new predictions when $N_f/N_c \gtrsim O(1)$.

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arXiv2025

Axion dark matter detection via shift current

We propose a novel method to detect axion dark matter based on a topological phenomenon known as the shift current. We make use of the second-order nonlinearity of the shift current by applying a strong oscillating electric field. This field enhances the axion-induced shift current signal and downconverts its frequency to a more accessible range. The nondissipative nature of the shift current allows us to achieve broadband detection via difference frequency generation. We demonstrate the possibility of probing QCD axions and axion-like particles using the properties of the type-I Weyl semimetal TaAs, targeting an axion mass of $O(10)\,\mathrm{meV}$, corresponding to a photon coupling of $g_{a\gamma\gamma} \simeq \mathcal{O}(10^{-11})\,\mathrm{GeV}^{-1}$.

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arXiv2024

Phase transition on superfluid vortices in Higgs-Confinement crossover

We propose a novel method to distinguish states of matter by identifying spontaneous symmetry breaking on extended objects, such as vortices, even in the absence of a bulk phase transition. As a specific example, we investigate the phase transition on superfluid vortices in the Higgs-confinement crossover using a $\mathrm{U}(1)_\mathrm{gauge} \times \mathrm{U}(1)_\mathrm{global}$ model. This model exhibits superfluidity of $\mathrm{U}(1)_\mathrm{global}$ symmetry and allows for a crossover between the Higgs and confinement regimes by varying the gauge coupling constant from weak to strong. We demonstrate that, on vortices, spontaneous breaking of the $\mathbb{Z}_2$ flavor symmetry occurs in the weak coupling (Higgs) regime, while it does not in the strong coupling (confinement) regime. We also confirm that those regimes are separated by a second-order phase transition through Monte Carlo simulations, whose universality class corresponds to the two-dimensional Ising model.

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arXiv2024

LHC EFT WG Note: Basis for Anomalous Quartic Gauge Couplings

In this note, we give a definitive basis for the dimension-eight operators leading to quartic -- but no cubic -- interactions among electroweak gauge bosons. These are often called anomalous quartic gauge couplings, or aQGCs. We distinguish in particular the CP-even ones from their CP-odd counterparts.

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arXiv2024

Exploration to early universe by Josephson Junction Switching Current Detector

In this paper, we propose a method to probe a Stochastic Gravitational Wave Background (SGWB) with Josephson Junction Switching Current Detector (JJSCD). The sensitivity for the shear can reach $h\simeq 10^{-19}$ realistically, $10^{-21}$ in the near future, $10^{-24}$ optimistically. If we utilize the enhancement factor from the ratio of the frequency, it is possible to reach further below the Big Bang Nucleosynthesis (BBN) bound. It will be interesting if we can access the region to discover a footprint of new physics.

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arXiv2023

Axion detection via superfluid $^3$He ferromagnetic phase and quantum measurement techniques

We propose to use the nuclear spin excitation in the ferromagnetic A1 phase of the superfluid $^3$He for the axion dark matter detection. This approach is striking in that it is sensitive to the axion-nucleon coupling, one of the most important features of the QCD axion introduced to solve the strong CP problem. We review a quantum mechanical description of the nuclear spin excitation and apply it to the estimation of the axion-induced spin excitation rate. We also describe a possible detection method of the spin excitation in detail and show that the combination of the squeezing of the final state with the Josephson parametric amplifier and the homodyne measurement can enhance the sensitivity. It turns out that this approach gives good sensitivity to the axion dark matter with the mass of $O(1) \, \mu \mathrm{eV}$ depending on the size of the external magnetic field. We estimate the parameters of experimental setups, e.g., the detector volume and the amplitude of squeezing, required to reach the QCD axion parameter space.

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arXiv2023

23, 381, 6242, 103268, 1743183, ...: Hilbert series for CP-violating operators in SMEFT

We introduce a systematic method to classify the Standard Model Effective Field Theory (SMEFT) operators based on their CP properties with the Hilbert series techniques. Our method makes it possible to enumerate operators violating CP symmetry in a few seconds. We present the complete classification of dimension eight operators under CP transformation, and the number of CP-odd or CP-violating operators are listed up to dimension 14. We also provide a companion code in FORM that allows anybody to reproduce our results.

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arXiv2022

Emergent higher-form symmetry in Higgs phases with superfluidity

We address emergent higher-form symmetry in Higgs phases with superfluidity. The emergent symmetry appears if a matter field is invariant under a transformation of a common subgroup of gauge and global $\mathrm{U}(1)$ symmetries. We explicitly construct the symmetry generator that is topological and gauge invariant in a low-energy effective theory. Such emergent symmetry is helpful to distinguish the Higgs and other phases with superfluidity, such as phases of QCD at finite density. We also discuss the possibility of phase transition between these phases.

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arXiv2022

Dynamics of Simplest Chiral Gauge Theories

Arguably, the simplest chiral gauge theories are $\mathrm{SO}(10)$ with $N_f$ fermion fields in the spinor representation {\bf 16}. We study their dynamics using their supersymmetric limits perturbed by an infinitesimal anomaly-mediated supersymmetry breaking as a guide. We predict the theory is gapped for $N_f=1,2$, while the $\mathrm{SU}(N_f)$ global symmetry is broken to $\mathrm{SO}(\mathrm{N}_f)$ for moderately large $N_f \geq 3$.

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arXiv2022

Linear Sigma Dark Matter

We present a model of self-interacting dark matter based on QCD-like theories and inspired by the proximity of $a_0(980\pm 20)$ to the $K\bar{K}(990)$ threshold. Dark matter is comprised of dark pions which self-scatter via the $σ$ resonance close to the $ππ$ threshold. While the linear sigma model serves as a qualitative guide, a fully unitary description of the scattering in the strongly coupled regime is given by effective range theory. The introduction of a kinetically mixed dark photon allows the dark pion to either freeze-out or -in. We study the viable parameter space which explains the observed relic abundance while evading all current constraints. Searches for dark matter self interactions at different scales, (in)direct detection signals, and (in)visibly-decaying dark photons will test this model in the near future.

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arXiv2021

Broken Conformal Window

We show that near the edges of the conformal window of supersymmetric $SU(N_c)$ QCD, perturbed by Anomaly Mediated Supersymmetry Breaking (AMSB), chiral symmetry can be broken depending on the initial conditions of the RG flow. We do so by perturbatively expanding around Banks--Zaks fixed points and taking advantage of Seiberg duality. Interpolating between the edges of the conformal window, we predict that non-supersymmetric QCD breaks chiral symmetry up to $N_f \leq 3N_c - 1$, while we cannot say anything definitive for $N_f \geq 3N_c$ at this moment.

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