Half-Integer Shapiro Steps in a Short Ballistic InAs Nanowire Josephson Junction

We report on half-integer Shapiro steps observed in an InAs nanowire Josephson junction. We observed the Shapiro steps of the short ballistic InAs nanowire Josephson junction and found anomalous half-integer steps in addition to the conventional integer steps. The half-integer steps disappear as the temperature increases or transmission of the junction decreases. These experimental results agree closely with numerical calculation of the Shapiro response for the skewed current phase relation in a short ballistic Josephson junction

Online Estimation of Self-Body Deflection With Various Sensor Data Based on Directional Statistics

In this paper, we propose a method for online estimation of the robot's posture. Our method uses von Mises and Bingham distributions as probability distributions of joint angles and 3D orientation, which are used in directional statistics. We constructed a particle filter using these distributions and configured a system to estimate the robot's posture from various sensor information (e.g., joint encoders, IMU sensors, and cameras). Furthermore, unlike tangent space approximations, these distributions can handle global features and represent sensor characteristics as observation noises. As an application, we show that the yaw drift of a 6-axis IMU sensor can be represented probabilistically to prevent adverse effects on attitude estimation. For the estimation, we used an approximate model that assumes the actual robot posture can be reproduced by correcting the joint angles of a rigid body model. In the experiment part, we tested the estimator's effectiveness by examining that the joint angles generated with the approximate model can be estimated using the link pose of the same model. We then applied the estimator to the actual robot and confirmed that the gripper position could be estimated, thereby verifying the validity of the approximate model in our situation.Comment: This work has been submitted to the IEEE for possible publication. Copyright may be transferred without notice, after which this version may no longer be accessibl

Asymmetric Mediator in Scotogenic Model

The scotogenic model is the Standard Model (SM) with Z_2 symmetry and the addition of Z_2 odd right-handed Majorana neutrinos and SU(2)_L doublet scalar fields. We have extended the original scotogenic model by an additional Z_2 odd singlet scalar field that plays a role in dark matter. In our model, the asymmetries of the lepton and Z_2 odd doublet scalar are simultaneously produced through CP-violating right-handed neutrino decays. While the former is converted into baryon asymmetry through the sphaleron process, the latter is relaid to the DM density through the decay of SU(2)_L doublet scalar that is named "asymmetric mediator". In this way, we provide an extended scotogenic model that predicts the energy densities of baryon and dark matter being in the same order of magnitude, and also explains the low-energy neutrino masses and mixing angles.Comment: 17 pages, 1 table, 5 figure

Contribution of Majoron to Hubble tension in gauged U(1)Lμ−Lτ_{L_\mu-L_\tau} Model

In this paper, we analyze parameter regions that can alleviate the Hubble tension in the U(1)$_{L_\mu - L_\tau}$ model with the broken lepton number U(1)$_L$ symmetry. As new particles, this model has a U(1)$_{L_\mu - L_\tau}$ gauge boson $Z'$ and a Majoron $\phi$, which can affect the early universe and the effective number of neutrino species $N_{\rm eff}$. If $Z'$ and $\phi$ simultaneously exist in the early universe, $Z'\,$-$\,\phi$ interaction processes such as $Z'\nu_\alpha \leftrightarrow \phi\bar{\nu}_\beta$ occur. The comparison of $N_{\rm eff}$ between the cases with and without the $Z'\,$-$\,\phi$ interaction processes shows that these processes make a small contribution of $\mathcal{O}(10^{-4})$ to $N_{\rm eff}$, and it does not need to be considered for the alleviation of the Hubble tension. Based on these facts, we calculated $N_{\rm eff}$ for various Majoron parameters without the $Z'\,$-$\,\phi$ interaction processes to search parameters that could alleviate the Hubble tension. As a result, we found that the U(1)$_{L_\mu - L_\tau}$ gauge boson and Majoron can alleviate the Hubble tension in some parameter regions, and there is a non-trivial synergy contribution between $Z'$ and $\phi$. Moreover, the parameter region with a lighter mass $m_\phi \lesssim 2$ MeV and a larger coupling $\lambda \gtrsim 10^{-8}$ is excluded because it predicts too large $N_{\rm eff}$, i.e. $N_{\rm eff} \gtrsim 3.5$. The favored and restricted regions of the Majoron parameters depend on the $Z'$ parameters because of the presence of the $Z'$ contribution and synergy one.Comment: 24 pages, 4 figure