On the accretion of phantom energy onto wormholes

By using a properly generalized accretion formalism it is argued that the accretion of phantom energy onto a wormhole does not make the size of the wormhole throat to comovingly scale with the scale factor of the universe, but instead induces an increase of that size so big that the wormhole can engulf the universe itself before it reaches the big rip singularity, at least relative to an asymptotic observer.Comment: 4 pages, LaTex, to appear in Phys. Lett.

Hairy black holes in theories with massive gravitons

This is a brief survey of the known black hole solutions in the theories of ghost-free bigravity and massive gravity. Various black holes exist in these theories, in particular those supporting a massive graviton hair. However, it seems that solutions which could be astrophysically relevant are the same as in General Relativity, or very close to them. Therefore, the no-hair conjecture essentially applies, and so it would be hard to detect the graviton mass by observing black holes.Comment: References added. 20 pages, 3 figures, based on the talk given at the 7-th Aegean Summer School "Beyond Einstein's theory of gravity", September 201

Suppressing Quantum Fluctuations in Classicalization

We study vacuum quantum fluctuations of simple Nambu-Goldstone bosons - derivatively coupled single scalar-field theories possessing shift-symmetry in field space. We argue that quantum fluctuations of the interacting field can be drastically suppressed with respect to the free-field case. Moreover, the power-spectrum of these fluctuations can soften to become red for sufficiently small scales. In quasiclassical approximation, we demonstrate that this suppression can only occur for those theories that admit such classical static backgrounds around which small perturbations propagate faster than light. Thus, a quasiclassical softening of quantum fluctuations is only possible for theories which classicalize instead of having a usual Lorentz invariant and local Wilsonian UV- completion. We illustrate our analysis by estimating the quantum fluctuations for the DBI-like theories.Comment: 6 pages, no figures, published version, more general discussion of uncertainty relation in QFT, improved and more general derivation of the main resul

The four fixed points of scale invariant single field cosmological models

We introduce a new set of flow parameters to describe the time dependence of the equation of state and the speed of sound in single field cosmological models. A scale invariant power spectrum is produced if these flow parameters satisfy specific dynamical equations. We analyze the flow of these parameters and find four types of fixed points that encompass all known single field models. Moreover, near each fixed point we uncover new models where the scale invariance of the power spectrum relies on having simultaneously time varying speed of sound and equation of state. We describe several distinctive new models and discuss constraints from strong coupling and superluminality.Comment: 24 pages, 6 figure

Монте-Карло моделирование фазового перехода адроны-КГП в столкновениях тяжелых ионов с помощью партонной модели

Quark gluon plasma (QGP) is a special state of nuclear matter where quarks and gluons behave like free particles. Recently, a number of investigations of this state with high temperature and/or density have been conducted using collisions of relativistic and ultra-relativistic heavy nuclei. It is accepted that depending on the temperature and density, 1st or the 2nd order phase transitions take place in hadron matter during the formation of QGP. Herein, we have modeled heavy ion collisions using a HIJING Monte-Carlo generator, taking into account the description of the 1st order phase transition as a probabilistic process. We analyzed the behavior of the fluctuations of the total (N = N+ – N–) and resultant (Q = N+ – N–) electric charges of the system. Different phases were introduced using the BDMPS (Baier – Dokshitzer – Mueller – Piegne – Schiff) model of parton energy loss during crossing through a dense nuclear medium.Кварк-глюонная плазма (КГП) является особым состоянием ядерной материи, при котором кварки и глюоны ведут себя как свободные частицы. В настоящее время проводятся исследования этого состояния вещества с высокими температурой и/или плотностью с помощью столкновений релятивистских и ультрарелятивистских тяжелых ядер. Считается, что адронная материя испытывает (в зависимости от температуры и плотности) фазовый переход первого или второго рода при образовании КГП. В данной статье были промоделированы столкновения тяжелых ионов с помощью Монте-Карло генератора HIJING с учетом описания фазового перехода первого рода как вероятностного процесса и проанализировано поведение флуктуаций полного (N = N+ – N–) и результирующего (Q = N+ – N–) электрических зарядов системы. Разные фазы были заданы с помощью BDMPS (Baier – Dokshitzer – Mueller – Piegne – Schiff) модели потери партонной энергии при прохождении через плотное ядерное вещество

Single particle nonlocality with completely independent reference states

We describe a scheme to demonstrate the nonlocal properties of a single particle by showing a violation of Bell's inequality. The scheme is experimentally achievable as the only inputs are number states and mixed states, which serve as references to `keep track of the experiment'. These reference states are created completely independently of one another and correlated only after all the measurement results have been recorded. This means that any observed nonlocality must solely be due to the single particle state. All the techniques used are equally applicable to massive particles as to photons and as such this scheme could be used to show the nonlocality of atoms.Comment: 10 pages, 5 figure

Compact boson stars in K field theories

We study a scalar field theory with a non-standard kinetic term minimally coupled to gravity. We establish the existence of compact boson stars, that is, static solutions with compact support of the full system with self-gravitation taken into account. Concretely, there exist two types of solutions, namely compact balls on the one hand, and compact shells on the other hand. The compact balls have a naked singularity at the center. The inner boundary of the compact shells is singular, as well, but it is, at the same time, a Killing horizon. These singular, compact shells therefore resemble black holes.Comment: Latex, 45 pages, 25 figures, some references and comments adde