The Experts below are selected from a list of 15 Experts worldwide ranked by ideXlab platform

Sidney Coleman - One of the best experts on this subject based on the ideXlab platform.

  • Notes from Sidney Coleman's Physics 253a
    2014
    Co-Authors: Sidney Coleman
    Abstract:

    These notes were taken by Brian Hill during Sidney Coleman's lectures on Quantum Field Theory (Physics 253), given at Harvard University in Fall semester of the 1986-1987 academic year. They were recently typeset and edited by Yuan-Sen Ting and Bryan Gin-ge Chen. Although most of topics in the second part of the course (Physics 253b) were assembled and published in Coleman's book "Aspects of Symmetry", these notes remain the principal source for the Physics 253a materials. [See also this http URL for a video version of the course given in 1975-1976. ]

  • Notes from Sidney Coleman's Physics 253a: Quantum Field Theory
    2011
    Co-Authors: Sidney Coleman
    Abstract:

    These notes were taken by Brian Hill during Sidney Coleman's lectures on Quantum Field Theory (Physics 253), given at Harvard University in Fall semester of the 1986-1987 academic year. They were recently typeset and edited by Yuan-Sen Ting and Bryan Gin-ge Chen. Although most of topics in the second part of the course (Physics 253b) were assembled and published in Coleman's book "Aspects of Symmetry", these notes remain the principal source for the Physics 253a materials. [See also http://www.Physics.harvard.edu/about/Phys253.html for a video version of the course given in 1975-1976. ]

N.j. Cornish - One of the best experts on this subject based on the ideXlab platform.

  • QUANTUM NONLOCAL Field Theory: Physics WITHOUT INFINITIES
    International Journal of Modern Physics A, 1992
    Co-Authors: N.j. Cornish
    Abstract:

    It is argued that nonlocality is an essential ingredient in Relativistic Quantum Field Theory in order to have finite Theory without recourse to a renormalisation program. A critical review of the physical constraints on the form the nonlocality can take is presented. The conclusion of this review is that nonlocality must be restricted to interactions with the vacuum sea of virtual particles. A successful formulation of such a Theory, QNFT, is applied to scalar electrodynamics and serves to illustrate how gauge invariance and manifest finiteness can be achieved. The importance of the infinite dimensional symmetry groups that occur in QNFT are discussed as an alternative to supersymmetry, the ability to generate masses by breaking the nonlocal symmetry with a noninvariant functional measure is given a critical assessment. To demonstrate some of the many novel applications QNFT may make possible two examples are mooted, the existence of electroweak monopoles and the formulation of a finite perturbative Theory of Quantum Gravity.

Howard Georgi - One of the best experts on this subject based on the ideXlab platform.

  • Unparticle Physics
    Physical Review Letters, 2007
    Co-Authors: Howard Georgi
    Abstract:

    I discuss some simple aspects of the low-energy Physics of a nontrivial scale invariant sector of an effective Field Theory -- Physics that cannot be described in terms of particles. I argue that it is important to take seriously the possibility that the unparticle stuff described by such a Theory might actually exist in our world. I suggest a scenario in which some details of the production of unparticle stuff can be calculated. I find that in the appropriate low energy limit, unparticle stuff with scale dimension $d_{\mathcal{U}}$ looks like a non-integral number $d_{\mathcal{U}}$ of invisible particles. Thus dramatic evidence for a nontrivial scale invariant sector could show up experimentally in missing energy distributions.

Walter Dittrich - One of the best experts on this subject based on the ideXlab platform.

  • Classical and Quantum Mechanics with Lie Brackets and Pseudocanonical Transformations
    arXiv: Quantum Physics, 2016
    Co-Authors: Walter Dittrich
    Abstract:

    We emphasize the usefulness of the Lie brackets in the context of classical and quantum mechanics. By way of examples we show that many dynamical systems, especially the ones with (gauge) constraints, can equally be treated in their time development with non-canonical variables and Hamiltonians. After a short presentation of the Lie bracket algebra and treating some easier standard problems with the Lie bracket techniques, we concentrate mainly on charged particles with gauge constraint in a constant external magnetic Field. Since most of our quantum Field theories are meanwhile considered effective, we have purposely treated our final problems with $c$-number instead of Field -operator Lagrangians. The van Vleck determinant, which is exact for our problems, is employed to calculate the $c$-number Feynman-Schwinger propagation function. There is no need for operators or renormalization. In particular, the non-relativistic propagator in $2+1$ dimensions and the more complicated one in $3+1$ dimensions are presented in all their glorious detail. On the more editorial side: we have dispensed with numerating the various problems. They are not so much disjoint that they needed an extra title. Also, the article is written in a self-consistent way, meaning one should be able to read it without time-consuming research in textbooks and journals - with a few exceptions, in particular Schwinger's paper [J. Schwinger, Phys. Rev. 82, 664 (1951)], which is the most-cited paper in modern quantum-Field-Theory Physics. Most of the prerequisites for reading the present article can be found in extenso in [W. Dittrich and M. Reuter, Classical and quantum dynamics (Springer, Berlin, Germany, 2016)].