Tesis S2 : Violation of The Equivalence Principle in ScalarTensor Theories of Gravity
Oleh : Andrias Fajarudin
Rabu, 8 September 2010 (06:34 WIB) dari IP 125.160.101.76
Naskah lengkap tersedia di halaman PUBLIKASI / TESIS MAHASISWA S2.
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Violation of The Equivalence Principle in ScalarTensor Theories of Gravity
Andrias Fajarudin
Diploma on HEP, Abdus Salam ICTP
Abstrak
In this thesis I study the violation of the equivalence principle induced by two screening mechanisms in scalartensor theories of gravity : the chameleon mechanism and the Vainshtein eﬀect. In the chameleon mechanism, the scalar ﬁeld acquires a mass which depends on the environment density such that it will be screened in a high density environments. I discuss the violation of the equivalence principle both in Einstein and in Jordan frames. In Einstein frame, unscreened objects will move with bigger acceleration compared to screened objects. In Jordan frame, only unscreened objects feel the chameleon ﬁeld whereas screened objects don’t. Consequently, only unscreened objects move on geodesics. This leads to order unity violation of the equivalence principle. In the Vainshtein mechanism, the screening of the scalar ﬁeld comes from derivative interaction that become large in the vicinity of massive objects. Perturbations of scalar in such regions acquire a large kinetic term and therefore decouple from matter. Thus, the scalar screens itself and become invisible to experiments. Vainshtein mechanism doesn’t lead to order unity violation of the equivalence principle. In this screening mechanism, equivalence principle violation occurs at a much reduced level.

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