Censorship Conjecture Research Articles

Negative scalar potentials and the swampland: an Anti-Trans-Planckian Censorship Conjecture

In this paper, we derive a characterisation of negative scalar potentials, V < 0, in d-dimensional effective theories of quantum gravity. This is achieved thanks to an Anti-Trans-Planckian Censorship Conjecture (ATCC), inspired by a refined version of the TCC. The ATCC relies on the fact that in a contracting universe, modes that become sub-Planckian in length violate the validity of the effective theory. In the asymptotics of field space, we deduce that −V′/V ≥ c0 when V′ ≥ 0. The rate {c}_0=2/sqrt{left(d-1right)left(d-2right)} is successfully tested in several string compactifications for d ≥ 4. In addition, a new asymptotic condition, V′′/V ≥ {c}_0^2 , is derived. By extrapolation to anti-de Sitter solutions of radius l, we infer the existence of a scalar whose mass should obey m2l2 ≲ −2. This property is verified in many supersymmetric examples.

De Sitter Bubbles and the Swampland

AbstractA number of Swampland conjectures and in particular the Trans‐Planckian Censorship Conjecture (TCC) suggest that de Sitter space is highly unstable if it exists at all. In this paper we construct effective theories of scalars rolling on potentials which are dual to a chain of short‐lived dS spaces decaying from one to the next through a cascade of non‐perturbative nucleation of bubbles. We find constraints on the effective potential resulting from various swampland criteria, including TCC, Weak Gravity Conjecture and Distance Conjecture. Surprisingly we find that TCC essentially incorporates all the other ones, and leads to a subclass of possible dual effective potentials. These results marginally rule out emergence of eternal inflation in the dual effective theory. We discuss some cosmological implications of our observations.

Non‐Standard Cosmological Models and The Trans‐Planckian Censorship Conjecture

AbstractThe trans‐Planckian censorship conjecture (TCC) puts an upper bound on the life‐time of de Sitter spacetimes. It has immediate consequences for inflationary cosmology. In the standard paradigm, the universe has experienced a single stage of inflation and follows a thermal history. Then, the TCC puts an upper bound on the Hubble parameter during inflation Hinf around 0.1 GeV. Consequently, it implies a severe fine‐tuning in initial condition for inflation and non‐detection of primordial gravitational waves. In this note, we study non‐standard cosmological paradigms with non‐thermal history and/or multiple stages of inflations. It is motivated by string theory compactifications and axiverse scenarios in which the modulus/axion fields are effective in the early universe. In early matter domination the TCC bound on Hinf can be raised up to 3 orders of magnitude. In multiple inflationary scenarios the upper bound on the observable inflation can be raised up 1014 GeV to touch the Planck 2018 bound.