S. P. de Alwis
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View article: Cosmology, Decoherence and the Second Law
Cosmology, Decoherence and the Second Law Open
We consider quantum decoherence and entropy increase in early universe cosmology. We first study decoherence in a discrete bipartite quantum system for which a single qubit gets entangled with an environment and the entropy increase is cor…
View article: Quantum transitions, detailed balance, black holes, and nothingness
Quantum transitions, detailed balance, black holes, and nothingness Open
We consider vacuum transitions by bubble nucleation among 4D vacua with different values and signs of the cosmological constant Λ, including both up and down tunnelings. Following the Hamiltonian formalism, we explicitly compute the transi…
View article: Quantum Transitions, Detailed Balance, Black Holes and Nothingness
Quantum Transitions, Detailed Balance, Black Holes and Nothingness Open
We consider vacuum transitions by bubble nucleation among 4D vacua with different values and signs of the cosmological constant $Λ$, including both up and down tunnelings. Following the Hamiltonian formalism, we explicitly compute the deca…
View article: Revisiting Vacuum decay in Field Theory
Revisiting Vacuum decay in Field Theory Open
We revisit the formalism for tunneling in quantum field theory developed by Coleman and collaborators. In particular using the generalization of WKB methods for tunneling in quantum mechanics we avoid the problems with negative eigenvalues…
View article: Comments on Entropy Calculations in Gravitational Systems
Comments on Entropy Calculations in Gravitational Systems Open
We discuss the logic of, and some puzzles in, the various approaches to thermodynamics of gravitational systems. In particular the blackhole, deSitter (dS), black hole in dS (SdS) and in Anti-deSitter SAdS backgrounds are considered. After…
View article: Density Perturbations and Primordial Non-Gaussianities in a Closed Universe
Density Perturbations and Primordial Non-Gaussianities in a Closed Universe Open
The spatial curvature of the universe is not yet known. Even though at present the Universe is very close to being essentially flat and most signatures of curvature appear to have been diluted by inflation, if the number of e-foldings duri…
View article: Radiative Generation of dS from AdS
Radiative Generation of dS from AdS Open
The large volume scenario (LVS) of type IIB string compactifications has a robust supersymmetry breaking minimum with a negative cosmological constant (CC). We argue that radiative corrections below the Kaluza-Klein (KK) scale can result i…
View article: Lorentzian vacuum transitions: Open or closed universes?
Lorentzian vacuum transitions: Open or closed universes? Open
We consider the generalisation of quantum tunneling transitions in the WKB\napproximation to the time-independent functional Schr\\"odinger and\nWheeler-DeWitt equations. Following a Lorentzian approach, we compute the\ntransition rates am…
View article: Wilsonian Effective Field Theory and String Theory
Wilsonian Effective Field Theory and String Theory Open
We argue that deriving an effective field theory from string theory requires a Wilsonian perspective with a physical cutoff. Employing proper time regularization we demonstrate the decoupling of states and contrast this with what happens i…
View article: Wave function of the Universe and CMB fluctuations
Wave function of the Universe and CMB fluctuations Open
The Hartle-Hawking and Tunneling (Vilenkin) wave functions are treated in the Hamiltonian formalism. We find that the leading (i.e. quadratic) terms in the fluctuations around a maximally symmetric background, are indeed Gaussian (rather t…
View article: Higher Derivative Corrections to Lower Order RG Flow Equations
Higher Derivative Corrections to Lower Order RG Flow Equations Open
We show that the RG flow equation for the cosmological constant (CC) receives contributions (in addition to those coming from the CC the Einstein-Hilbert term and $R^{2}$ and $R_{μν}^{2}$ terms) only from terms with just two powers of curv…
View article: Constraints on Dbar Uplifts
Constraints on Dbar Uplifts Open
We discuss constraints on KKLT/KKLMMT and LVS scenarios that use anti-branes to get an uplift to a deSitter vacuum, coming from requiring the validity of an effective field theory description of the physics. We find these are not always sa…
View article: Robust Inflation from fibrous strings
Robust Inflation from fibrous strings Open
Successful inflationary models should (i) describe the data well; (ii) arise generically from sensible UV completions; (iii) be insensitive to detailed fine-tunings of parameters and (iv) make interesting new predictions. We argue that a c…