1,755,551 research outputs found
Physics of unstable nuclei : proceedings of the 10th Yukawa International Seminar, Yukawa Institute for Theoretical Physics, Kyoto, Japan, November 5-10, 2001 /
No full text"Published for the Yukawa Institute Institute for Theoretical Physics and the Physical Society of Japan."Includes bibliographical references and index
A course in theoretical physics
No full textThis book is a comprehensive account of five extended modules covering the key branches of twentieth-century theoretical physics, taught by the author over a period of three decades to students on bachelor and master university degree courses in both physics and theoretical physics. The modules cover nonrelativistic quantum mechanics, thermal and statistical physics, many-body theory, classical field theory (including special relativity and electromagnetism), and, finally, relativistic quantum mechanics and gauge theories of quark and lepton interactions, all presented in a single, self-contained volume. In a number of universities, much of the material covered (for example, on Einstein’s general theory of relativity, on the BCS theory of superconductivity, and on the Standard Model, including the theory underlying the prediction of the Higgs boson) is taught in postgraduate courses to beginning PhD students. A distinctive feature of the book is that full, step-by-step mathematical proofs of all essential results are given, enabling a student who has completed a high-school mathematics course and the first year of a university physics degree course to understand and appreciate the derivations of very many of the most important results of twentieth-century theoretical physics.This book is a comprehensive account of five extended modules covering the key branches of twentieth-century theoretical physics, taught by the author over a period of three decades to students on bachelor and master university degree courses in both physics and theoretical physics. The modules cover nonrelativistic quantum mechanics, thermal and statistical physics, many-body theory, classical field theory (including special relativity and electromagnetism), and, finally, relativistic quantum mechanics and gauge theories of quark and lepton interactions, all presented in a single, self-con
Type IIB Orientifolds, D-Brane Instantons And The Large Volume Scenario
Full text linkThis review article is concerned with three topics important for the construction of four-dimensional models of particle physics in the context of type II String Theories. Special emphasis is put on a consistent presentation of these topics as well as on highlighting their interconnections. The first of the three topics deals with the tadpole cancellation conditions and the cancellation of chiral anomalies for type IIB orientifolds with orientifold three-and seven-planes. The second topic is related to non-perturbative effects originating from D-brane instantons. In particular, in the presence of a realistic particle physics sector, a chiral zeromode constraint for contribution of instantons to the superpotential arises. The third topic is about moduli stabilisation in type IIB string compactifications. Two scenarios, the KKLT and Large Volume Scenario, are reviewed and a model for the latter scenario with the chiral zero-mode constraint taken into account is presente
Dynamics driven by the trace anomaly in FLRW universes
No full textBy means of a semiclassical analysis we show that the trace anomaly does not affect the cosmological constant. We calculate the evolution of the Hubble parameter in quasi de Sitter spacetime, where the Hubble parameter varies slowly in time, and in FLRW spacetimes. We show dynamically that a Universe consisting of matter with a constant equation of state, a cosmological constant and the quantum trace anomaly evolves either to the classical de Sitter attractor or to a quantum trace anomaly driven one. There is no dynamical effect that influences the effective value of the cosmological constan
Isomeric decays in neutron-rich W, Os and Pt nuclei
No full textRelativistic energy fragmentation of a 1 GeV/nucleon Pb-208 beam was used to populate a wide range of nuclei on both sides of the valley of beta-stability. The structure of these nuclei was studied by the identification of discrete gamma-ray transitions depopulating isomeric states with lifetimes in the nano- to millisecond range. Highlights of the experiment include the first observation of gamma-ray transitions in the neutron-rich nuclei (188)TA, W-190, Re-192, Os-195, Ir-197,Ir-198, Pt-201,Pt-202. The yrast states in W-190 and Pt-202 as well as the decay out from 10-20 ns isomers in Pt-202,Pt-201 and Os-195 are discussed. The observation of the previously reported isomeric K = 35/2 states in Hf-175, W-179 and Re-181 represents the highest discrete spin states observed to date following a projectile fragmentation reaction
Theoretical physics and astrophysics
No full textThe aim of this book is to present, on the one hand various topics in theoretical physics in depth - especially topics related to electrodynamics - and on the other hand to show how these topics find applications in various aspects of astrophysics. The first text on theoretical physics and astrophysical applications, it covers many recent advances including those in X-ray, &ggr;-ray and radio-astronomy, with comprehensive coverage of the literatur
Improved Holographic QCD and the Quark-gluon Plasma
No full textWe review construction of the improved holographic models for QCD-like confining gauge theories and their applications to the physics of the quark–gluon plasma. We also review recent progress in this area of research. The lecture notes start from the vacuum structure of these theories, then develop calculation of thermodynamic and hydrodynamic observables, energy loss and momentum broadening of heavy probes, and end with more advanced topics such as the holographic QCD in the presence of external magnetic fields. This is a summary of the lectures presented at the LVI Cracow School of Theoretical Physics in spring 2016 at Zakopane, Poland
Quantum Field Theory and Decoherence in the Early Universe
No full textQuantum field theory is indispensable for understanding many aspects of cosmology, both in the early Universe and today. For example, quantum processes could be paramount to understand the nature of the mysterious dark energy resulting in the Universe’s recently observed accelerated expansion. Inspired by these considerations, this PhD thesis is concerned with two aspects of quantum field theory relevant to cosmology: quantum backreaction and decoherence. Quantum backreaction is a line of research where the impact of quantum fluctuations on the background spacetime geometry in perturbative quantum gravity is investigated. The cosmological constant problem and the process of quantum backreaction are intimately related: quantum backreaction might provide us with a dynamical mechanism to effectively make the cosmological constant almost vanish. We investigate the quantum backreaction of the trace anomaly and of fermions. We find that the trace anomaly does not dynamically influence the effective value of the cosmological constant. We furthermore evaluate the fermion propagator in FLRW spacetimes with constant deceleration. Although the dynamics resulting from the one-loop stress-energy tensor need yet to be investigated, we find that we certainly cannot exclude a significant effect due to the quantum backreaction on the Universe’s expansion. Decoherence is a quantum theory which addresses the quantum-to-classical transition of a particular system. The idea of the decoherence formalism is that a macroscopic system cannot be separated from its environment. The framework of decoherence is widely used, e.g. in quantum computing, black hole physics, inflationary perturbation theory, and in elementary particle physics, such as electroweak baryogenesis models. We formulate a novel “correlator approach” to decoherence: neglecting observationally inaccessible correlators gives rise to an increase in entropy of the system, as perceived by an observer. This is inspired by realising that higher order, non-Gaussian correlators are usually perturbatively suppressed. A quantum system with a large entropy corresponds to an effectively classical, stochastic system. To allow for a quantitative comparison between our correlator approach and the conventional approach to decoherence, we apply both formalisms to two simple quantum mechanical models. We find that the entropy in the conventional approach to decoherence quite generically reveals secular growth, indicating physically unacceptable behaviour. The conventional approach furthermore suffers from the fact that no well-established treatment to take perturbative corrections into account exists, nor has the framework of renormalisation ever been implemented. Our correlator approach to decoherence is taylored to applications in quantum field theory. We perform the first realistic study of decoherence in a renormalised quantum field theoretical setting. Using out-of-equilibrium field theory techniques, we extract two quantitative measures of decoherence in our model: the total amount of decoherence and the decoherence rate. The main finding in this part of the thesis is that, although a pure state remains pure under unitary evolution, an observer perceives this state over time as a mixed state with positive entropy as non-Gaussianities are dynamically generated. Alternatively, one could say that a realistic observer cannot probe all information about the system and thus discerns a loss of coherence of the pure stat
New deformations of N=2 supergravity
No full textSupergravity is a field theory that combines general relativity with local supersymmetry. It serves as a framework for studying a large variety of phenomena, such as black holes and cosmology. Supergravity also describes the low-energy degrees of freedom associated with string theory, which has been proposed as a consistent theory of quantum gravity. In this thesis we study new deformations of N=2 supergravity in four space-time dimensions. One class of deformations we consider consists of gauge deformations. Applying the so-called embedding tensor formalism, we present general gauge deformations of N=2 supergravity, which, due to the presence of electric/magnetic duality, lead to the introduction of both electric and magnetic charges. As an application we briefly review partial supersymmetry breaking in maximally symmetric space-times in the presence of general gaugings. We confirm the result found in previous literature, that in a Minkowski background, partial supersymmetry breaking is only possible in the presence of magnetic charges. As a new application we study possible supersymmetric solutions in space-times that describe the near-horizon geometry of a static black hole. We find two classes of solutions. One is fully supersymmetric. It contains the near-horizon solution of ungauged supergravity that appears for BPS black holes. The other class exhibits four supersymmetries. It contains near-horizon solutions of BPS black holes in N=2 gauged supergravity. Other deformations we consider in this thesis are supersymmetric higher-derivative couplings. These couplings play an important role as next-to-leading order corrections to low-energy effective actions of string theory. In this thesis we introduce a systematic procedure to construct a large variety of new higher-derivative deformations in N=2 supergravity. We study the possible contribution of these new couplings to the entropy and the electric charges of BPS black holes. We derive a 'non-renormalization' theorem according to which these contributions vanish
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