Search for: All records

A<sc>bstract</sc> 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 toN_f≤ 3N_c− 1, while we cannot say anything definitive forN_f≥ 3N_cat this moment. 

A<sc>bstract</sc> We propose to use the nuclear spin excitation in the ferromagnetic A₁phase of the superfluid³He 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$$ \mathcal{O} $$ $O$(1) μeV 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. 

A<sc>bstract</sc> The strong CP problem is solved in Parity symmetric theories, with the electroweak gauge group containing SU(2)_L× SU(2)_Rbroken by the minimal set of Higgs fields. Neutrino masses may be explained by adding the same number of gauge singlet fermions as the number of generations. The neutrino masses vanish at tree-level and are only radiatively generated, leading to larger couplings of right-handed neutrinos to Standard Model particles than with the tree-level seesaw mechanism. We compute these radiative corrections and the mixing angles between left- and right-handed neutrinos. We discuss sensitivities to these right-handed neutrinos from a variety of future experiments that search for heavy neutral leptons with masses from tens of MeV to the multi-TeV scale. 

Abstract Extensive air showers induced from high-energy cosmic rays provide a window into understanding the most energetic phenomena in the universe. We present a new method for observing these showers using the silicon imaging detector Subaru Hyper Suprime-Cam (HSC). This method has the advantage of being able to measure individual secondary particles. When paired with a surface detector array, silicon imaging detectors like Subaru HSC will be useful for studying the properties of extensive air showers in detail. The following report outlines the first results of observing extensive air showers with Subaru HSC. The potential for reconstructing the incident direction of primary cosmic rays is demonstrated and possible interdisciplinary applications are discussed. 

We present exact nonperturbative vacuum solutions to chiral gauge theories based on the $E_6$gauge group and several matter fermions in the fundamental $27$-dimensional representation. They are obtained when supersymmetric versions are perturbed by small supersymmetry breaking by anomaly mediation. The universality classes obtained are very different from what can be conjectured by the tumbling hypothesis. In particular, the case with three $27\mathrm{s}$may have an unbroken SU(3) symmetry with massless composite fermions in $10$of SU(3). For this case, we employed numerical techniques to obtain the exact ground state. 

Inverse decays are an interesting avenue for producing dark matter in the early Universe. We study in detail various phases of dark matter parameter space where inverse decays control its abundance, expanding on our work of inverse decay (INDY) dark matter and going beyond. The role of initial conditions and the impact of departure from kinetic equilibrium are investigated as well. We show how these inverse decay phases can arise in theories of a kinetically mixed dark photon and dark Higgs, with promising prospects for detection at upcoming experiments. 

We present exact results in softly broken supersymmetric $\mathrm{SU}\left(N_C\right)$chiral gauge theories with charged fermions in one antisymmetric, $N_F$fundamental, and $N_C+N_F-4$antifundamental representations. We achieve this by considering the supersymmetric version of these theories and utilizing anomaly mediated supersymmetry breaking at a scale $m\ll \mathrm{\Lambda }$to generate a vacuum. The connection to nonsupersymmetric theories is then conjectured in the limit $m\to \infty$. For odd $N_C$, we determine the massless fermions and unbroken global symmetries in the infrared. For even $N_C$, we find global symmetries are nonanomalous and no massless fermions. In all cases, the symmetry breaking patterns differ from what the tumbling hypothesis would suggest. 

We introduce a class of multi-Higgs doublet extensions of the Standard Model that solve the strong $CP$problem with profound consequences for the flavor sector. The Yukawa matrices are constrained to have many zero entries by a “Higgs-flavor” symmetry, $G_{\mathrm{HF}}$, that acts on Higgs and quark fields. The violation of both $CP$and $G_{\mathrm{HF}}$occurs in the Higgs mass matrix so that, for certain choices of $G_{\mathrm{HF}}$charges, the strong $CP$parameter $\overline{\theta }$is zero at tree level. Radiative corrections to $\overline{\theta }$are computed in this class of theories. They vanish in realistic two-Higgs doublet models with $G_{\mathrm{HF}}={\mathbb{Z}}_3$. We also construct realistic three-Higgs models with $G_{\mathrm{HF}}=\mathrm{U}\left(1\right)$, where the one-loop results for $\overline{\theta }$are model-dependent. Requiring $\overline{\theta }<{10}^{-10}$has important implications for the flavor problem by constraining the Yukawa coupling and Higgs mass matrices. Contributions to $\overline{\theta }$from higher-dimension operators are computed at one loop and can also be sufficiently small, although the hierarchy problem of this class of theories is worse than in the Standard Model.