| Autor: |
Araki, Takeshi, Asai, Kento, Honda, Kei, Kasuya, Ryuta, Sato, Joe, Shimomura, Takashi, Yang, Masaki J S |
| Předmět: |
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| Zdroj: |
Progress of Theoretical & Experimental Physics: PTEP; Oct2021, Vol. 2021 Issue 10, p1-16, 16p |
| Abstrakt: |
We explore the possibility of resolving the Hubble tension and |$(g-2)_{\mu}$| anomaly simultaneously in a U(1) |$_{L_\mu - L_\tau}$| model with Majoron. We only focus on the case where the Majoron |$\phi$| does not exist at the beginning of the universe and is created by neutrino inverse decay |$\nu\nu\to \phi$| after electron–positron annihilation. In this case, the contributions of the new gauge boson |$Z'$| and the Majoron |$\phi$| to the effective number of neutrino species |$N_{\rm eff}$| can be calculated in separate periods. These contributions are labelled |$N'_{\rm eff}$| for the U(1) |$_{L_\mu - L_\tau}$| gauge boson and |$\Delta N_{\rm eff}^\prime$| for the Majoron. The effective number |$N_{\rm eff} = N'_{\rm eff} + \Delta N_{\rm eff}^\prime$| is evaluated by the evolution equations of the temperatures and the chemical potentials of light particles in each period. As a result, we find that the heavier |$Z'$| mass |$m_{Z^\prime}$| results in a smaller |$N_{\mathrm{eff}}^\prime$| and requires a larger |$\Delta N_{\mathrm{eff}}^\prime$| to resolve the Hubble tension. Therefore, compared to previous studies, the parameter region where the Hubble tension can be resolved is slightly shifted toward the larger value of |$m_{Z^\prime}$|. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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