Communication with SIMP dark mesons via Z'-portal

We consider a consistent extension of the SIMP models with dark mesons by including a dark U(1)_D gauge symmetry. Dark matter density is determined by a thermal freeze-out of the $3\to2$ self-annihilation process, thanks to the Wess-Zumino-Witten term. In the presence of a gauge kinetic mixing between the dark photon and the SM hypercharge gauge boson, dark mesons can undergo a sufficient scattering off the Standard Model particles and keep in kinetic equilibrium until freeze-out in this SIMP scenario. Taking the SU(N_f)xSU(N_f)/SU(N_f) flavor symmetry under the SU(N_c) confining group, we show how much complementary the SIMP constraints on the parameters of the dark photon are for current experimental searches for dark photon.Comment: 16 pages, 6 figures, To appear in Phys. Lett.

SIMP dark matter and its cosmic abundances

We give a review on the thermal average of the annihilation cross-sections for $3\rightarrow 2$ and general higher-order processes. Thermal average of higher order annihilations highly depend on the velocity of dark matter, especially, for the case with resonance poles. We show such examples for scalar dark matter in gauged $Z_3$ models.Comment: 5 pages, 2 figures, Prepared for the proceedings of the 13th International Conference on Gravitation, 3-7 July 201

Cosmic abundances of SIMP dark matter

Thermal production of light dark matter with sub-GeV scale mass can be attributed to $3\rightarrow 2$ self-annihilation processes. We consider the thermal average for annihilation cross sections of dark matter at $3\rightarrow 2$ and general higher-order interactions. A correct thermal average for initial dark matter particles is important, in particular, for annihilation cross sections with overall velocity dependence and/or resonance poles. We apply our general results to benchmark models for SIMP dark matter and discuss the effects of the resonance pole in determining the relic density.Comment: 21 pages, 6 figures, Version to appear in Journal of High Energy Physic

Self-Supervised Curriculum Generation for Autonomous Reinforcement Learning without Task-Specific Knowledge

A significant bottleneck in applying current reinforcement learning algorithms to real-world scenarios is the need to reset the environment between every episode. This reset process demands substantial human intervention, making it difficult for the agent to learn continuously and autonomously. Several recent works have introduced autonomous reinforcement learning (ARL) algorithms that generate curricula for jointly training reset and forward policies. While their curricula can reduce the number of required manual resets by taking into account the agent's learning progress, they rely on task-specific knowledge, such as predefined initial states or reset reward functions. In this paper, we propose a novel ARL algorithm that can generate a curriculum adaptive to the agent's learning progress without task-specific knowledge. Our curriculum empowers the agent to autonomously reset to diverse and informative initial states. To achieve this, we introduce a success discriminator that estimates the success probability from each initial state when the agent follows the forward policy. The success discriminator is trained with relabeled transitions in a self-supervised manner. Our experimental results demonstrate that our ARL algorithm can generate an adaptive curriculum and enable the agent to efficiently bootstrap to solve sparse-reward maze navigation tasks, outperforming baselines with significantly fewer manual resets.Comment: 8 pages, 5 figure

Issues and Trends in Cross-border E-commerce in Korea

Consumers purchase cross-border e-commerce products directly from overseas online shopping malls. An increase in the popularity of cross-border e-commerce means that smart consumption trends revolutionized the consumption process. The scale of cross-border e-commerce in Korea reached a record high in 2017. Existing literature suggests that the sharp increase is due to price, product diversity, efficient shipping, expansion of duty-free range and hedonic motivation. A semantic network analysis revealed three main clusters in relationships between cross-border e-commerce research subjects: consumer, country and process

CMB Spectral μ\mu-Distortion of Multiple Inflation Scenario

In multiple inflation scenario having two inflations with an intermediate matter-dominated phase, the power spectrum is estimated to be enhanced on scales smaller than the horizon size at the beginning of the second inflation, $k > k_{\rm b}$. We require $k_{\rm b} > 10 {\rm Mpc}^{-1}$ to make sure that the enhanced power spectrum is consistent with large scale observation of cosmic microwave background (CMB). We consider the CMB spectral distortions generated by the dissipation of acoustic waves to constrain the power spectrum. The $\mu$-distortion value can be $10$ times larger than the expectation of the standard $\Lambda$CDM model ($\mu_{\Lambda\mathrm{CDM}} \simeq 2 \times 10^{-8}$) for $k_{\rm b} \lesssim 10^3 {\rm Mpc}^{-1}$, while the $y$-distortion is hardly affected by the enhancement of the power spectrum.Comment: 16 pages, 5 figure