**Strings and Fields
Group Seminar**

KEK理論センター 弦と場グループセミナー

TITLE： |
1. An introduction to string phenomenology 2. Cosmology in LARGE volume string models |

SPEAKER： |
Dr. Tetsutaro Higaki （檜垣徹太郎氏）
(KEK) |

LANGUAGE： | Up to audience |

DATE： | May 29 (Tue.) 13:30 − 15:00 (1st talk) and 15:30 − 17:00 (2nd talk) |

PLACE: | Kenkyu-Honkan 1F, Meeting Room 1 |

（ABSTRACT）

In the first talk, we will give an overview of string phenomenology.

In the second talk, we will argue cosmology in 4 dimensional N=1 supergravity which can be derived from type IIB supergravity in flux vacua. We will show that dark radiation, which is a reletivistic dark matter, is naturally generated from the decay of the overall volume modulus in the LARGE volume scenario. Then, the axionic superpartner of the modulus accounts for the dark radiation, which is constrained by the observation of CMB by the Planck satellite, while the modulus decay into Higgses through the Giudice-Masiero term gives the contribution to a reheating temperature of our sector. To obtain a viable reheating, we need, say, 9 Higgs doublet pairs; otherwise too much dark radiation is obtained. Hence, this illustrates a new type of moduli problem: Moduli-induced axion problem. Then, if viable, we can find also the candidates of cold (non-relativistic) dark matter, which are Wino and/or QCD axion.