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Target space supersymmetric sigma model techniques

Description: We briefly review the covariant formulation of the Green-Schwarz superstring by Berkovits, and describe how a detailed tree-level and one-loop analysis of this model leads, for the first time, to a derivation of the low-energy effective action of the heterotic superstring while keeping target-space supersymmetry manifest. The resulting low-energy theory is old-minimal supergravity coupled to tensor multiplet. The dilaton is part of the compensator multiplet.
Date: July 1, 1996
Creator: de Boer, Jan & Skenderis, Kostas
Partner: UNT Libraries Government Documents Department

Quantum gravity slows inflation

Description: We consider the quantum gravitational back-reaction on an initially inflating, homogeneous and isotropic universe whose topology is T{sup 3} {times} {Re}. Although there is no secular effect at one loop, an explicit calculation shows that two-loop processes act to slow the rate of expansion by an amount which becomes non-pertubatively large at late times. By exploiting Feynman`s tree theorem we show that all higher loops act in the same sense. 18 refs., 1 fig.
Date: February 1, 1996
Creator: Tsamis, N.C. & Woodard, R.P.
Partner: UNT Libraries Government Documents Department

The quantum gravitational back-reaction on inflation

Description: We describe our recent calculation of the dominant late time behavior of the expectation value of the metric at two loops in a locally de Sitter background on the manifold T{sup 3} {times} {Re}. If correct, our result proves that quantum gravitational effects slow the rate of inflation by an amount which becomes non-perturbatively large at late times. 11 refs., 9 figs., 11 tabs.
Date: February 1, 1995
Creator: Tsamis, N.C. & Woodard, R.P.
Partner: UNT Libraries Government Documents Department

Infinitely Large New Dimensions

Description: We construct intersecting brane configurations in Anti-de-Sitter space localizing gravity to the intersection region, with any number n of extra dimensions. This allows us to construct two kinds of theories with infinitely large new dimensions, TeV scale quantum gravity and sub-millimeter deviations from Newton's Law. The effective 4D Planck scale M{sub Pl} is determined in terms of the fundamental Planck scale M{sub *} and the AdS radius of curvature L via the familiar relation M{sub Pl}{sup 2} {approx} M{sub *}{sup 2+n} L{sup n}; L acts as an effective radius of compactification for gravity on the intersection. Taking M{sub *} {approx} TeV and L {approx} sub-mm reproduces the phenomenology of theories with large extra dimensions. Alternately, taking M{sub *} {approx} L{sup -1} {approx} M{sub Pl}, and placing our 3-brane a distance {approx} 100M{sub Pl}{sup -1} away from the intersection gives us a theory with an exponential determination of the Weak/Planck hierarchy.
Date: July 29, 1999
Creator: Arkani-Hamed, Nima; Dimopoulos, Savas; Dvali, Gia & Kaloper, Nemanja
Partner: UNT Libraries Government Documents Department

Harmonic resolution as a holographic quantum number

Description: The Bekenstein bound takes the holographic principle into the realm of flat space, promising new insights on the relation of non-gravitational physics to quantum gravity. This makes it important to obtain a precise formulation of the bound. Conventionally, one specifies two macroscopic quantities, mass and spatial width, which cannot be simultaneously diagonalized. Thus, the counting of compatible states is not sharply defined. The resolution of this and other formal difficulties leads naturally to a definition in terms of discretized light-cone quantization. In this form, the area difference specified in the covariant bound converts to a single quantum number, the harmonic resolution K. The Bekenstein bound then states that the Fock space sector with K units of longitudinal momentum contains no more than exp(2 pi^2 K) independent discrete states. This conjecture can be tested unambiguously for a given Lagrangian, and it appears to hold true for realistic field theories, including models arising from string compactifications. For large K, it makes contact with more conventional but less well-defined formulations.
Date: January 31, 2004
Creator: Bousso, Raphael
Partner: UNT Libraries Government Documents Department

Flat space physics from holography

Description: We point out that aspects of quantum mechanics can be derived from the holographic principle, using only a perturbative limit of classical general relativity. In flat space, the covariant entropy bound reduces to the Bekenstein bound. The latter does not contain Newton's constant and cannot operate via gravitational backreaction. Instead, it is protected by--and in this sense, predicts--the Heisenberg uncertainty principle.
Date: February 6, 2004
Creator: Bousso, Raphael
Partner: UNT Libraries Government Documents Department

Determination of the Atmospheric Neutrino Flux and Searches for New Physics with AMANDA-II

Description: The AMANDA-II detector, operating since 2000 in the deep ice at the geographic South Pole, has accumulated a large sample of atmospheric muon neutrinos in the 100 GeV to 10 TeV energy range. The zenith angle and energy distribution of these events can be used to search for various phenomenological signatures of quantum gravity in the neutrino sector, such as violation of Lorentz invariance (VLI) or quantum decoherence (QD). Analyzing a set of 5511 candidate neutrino events collected during 1387 days of livetime from 2000 to 2006, we find no evidence for such effects and set upper limits on VLI and QD parameters using a maximum likelihood method. Given the absence of evidence for new flavor-changing physics, we use the same methodology to determine the conventional atmospheric muon neutrino flux above 100 GeV.
Date: June 2, 2009
Creator: Collaboration, IceCube; Klein, Spencer & Collaboration, IceCube
Partner: UNT Libraries Government Documents Department

Massless versus Kaluza-Klein gravitons at the LHC

Description: We show that the LHC will be able to differentiate between a four-dimensional model with quantum gravity at {approx} 1 TeV where the (massless) graviton becomes strongly coupled to standard model particles at 1 TeV and brane world type models with a large extra-dimensional volume and massive Kaluza-Klein gravitons. We estimate that the 14 TeV LHC could put a limit of the order of {approx} 5 TeV on the four dimensional Planck mass in a model independent way.
Date: August 26, 2010
Creator: Calmet, Xavier; U., /Sussex; de Aquino, Priscila; /Louvain U., CP3 /Leuven U.; Rizzo, Thomas G. & /SLAC
Partner: UNT Libraries Government Documents Department

Bit-string physics: A novel theory of everything

Description: We encode the quantum numbers of the standard model of quarks and leptons using constructed bitstrings of length 256. These label a grouting universe of bit-strings of growing length that eventually construct a finite and discrete space-time with reasonable cosmological properties. Coupling constants and mass ratios, computed from closure under XOR and a statistical hypothesis, using only {h_bar}, c and m{sub p} to fix our units of mass, length and time in terms of standard (meterkilogram-second) metrology, agree with the first four to seven significant figures of accepted experimental results. Finite and discrete conservation laws and commutation relations insure the essential characteristics of relativistic quantum mechanics, including particle-antiparticle pair creation. The correspondence limit in (free space) Maxwell electromagnetism and Einstein gravitation is consistent with the Feynman-Dyson-Tanimura ``proof.``
Date: August 1, 1994
Creator: Noyes, H.P.
Partner: UNT Libraries Government Documents Department

CPT and superstring

Description: The authors discuss the possibility that CPT violation may appear as a consequence of microscopic decoherence due to quantum-gravity effects, that they describe using a density-matrix formalism motivated by their studies of non-critical string theory. The maximum possible order of magnitude of such decohering CPT-violating effects is not far from the sensitivity of present experiments on the neutral kaon system, and they review a simple parametrization for them. The authors also review a recent data analysis carried out together with the CPLEAR collaboration, which bounds any such decohering CPT-violating parameters to be {approx_lt} 10{sup {minus}19} GeV.
Date: July 1, 1996
Creator: Ellis, J.; Mavromatos, N.E. & Nanopoulos, D.V.
Partner: UNT Libraries Government Documents Department

Reduce phase space quantization of Ashtekar's gravity on de Sitter background

Description: The authors solve perturbative constraints and eliminate gauge freedom for Ashtekar's gravity on de Sitter background. They show that the reduced phase space consists of transverse, traceless, symmetric, fluctuations of the triad and of transverse, traceless, symmetric fluctuations of the connection. A part of gauge freedom corresponding to the conformal Killing vectors of the three-manifold can be fixed only by imposing conditions on Lagrange multiplier. The reduced phase space is equivalent to that of ADM gravity on the same background.
Date: May 1, 1994
Creator: Grigentch, I. & Vassilevich, D.V.
Partner: UNT Libraries Government Documents Department

QCD Phase Transitions-Volume 15.

Description: The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some. efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.
Date: November 4, 1998
Creator: Schafer, T.
Partner: UNT Libraries Government Documents Department

E. Cartan moment of rotation in classical and quantum gravity. Final report

Description: The geometric construction of the E. Cartan moment of rotation associated to the spacetime curvature provides a geometric interpretation of the gravitational field sources and describes geometrically how the sources are ``wired`` to the field in standard geometrodynamics. E. Cartan moment of rotation yields an alternate way (as opposed to using variational principles) to obtain Einstein equations. The E. Cartan construction uses in an essential way the soldering structure of the frame bundle underlying the geometry of the gravitational field of general relativity. The geometry of Ashtekar`s connection formulation of gravitation theory is based on a complex-valued self-dual connection that is defined not on the frame bundle of spacetime but, rather, on its complexification. We show how to transfer the construction of the E. Cartan moment of rotation to Ashtekar`s theory of gravity and demonstrate that no spurious equations are produced via this procedure.
Date: May 25, 1994
Creator: Kheyfets, A.
Partner: UNT Libraries Government Documents Department

One loop graviton self-energy in a locally de Sitter background

Description: The graviton tadpole has recently been computed at two loops in a locally de Sitter background. We apply intermediate results of this work to exhibit the graviton self-energy at one loop. This quantity is interesting both to check the accuracy of the first calculation and to understand the relaxation effect it reveals. In the former context we show that the self-energy obeys the appropriate Ward identity. We also show that its flat space limit agrees with the flat space result obtained by Capper in what should be the same gauge. 15 refs., 4 figs., 10 tabs.
Date: February 1996
Creator: Tsamis, N. C. & Woodard, R.P.
Partner: UNT Libraries Government Documents Department

QCD Phase Transitions, Volume 15

Description: The title of the workshop, ''The QCD Phase Transitions'', in fact happened to be too narrow for its real contents. It would be more accurate to say that it was devoted to different phases of QCD and QCD-related gauge theories, with strong emphasis on discussion of the underlying non-perturbative mechanisms which manifest themselves as all those phases. Before we go to specifics, let us emphasize one important aspect of the present status of non-perturbative Quantum Field Theory in general. It remains true that its studies do not get attention proportional to the intellectual challenge they deserve, and that the theorists working on it remain very fragmented. The efforts to create Theory of Everything including Quantum Gravity have attracted the lion share of attention and young talent. Nevertheless, in the last few years there was also a tremendous progress and even some shift of attention toward emphasis on the unity of non-perturbative phenomena. For example, we have seen some efforts to connect the lessons from recent progress in Supersymmetric theories with that in QCD, as derived from phenomenology and lattice. Another example is Maldacena conjecture and related development, which connect three things together, string theory, super-gravity and the (N=4) supersymmetric gauge theory. Although the progress mentioned is remarkable by itself, if we would listen to each other more we may have chance to strengthen the field and reach better understanding of the spectacular non-perturbative physics.
Date: March 20, 1999
Creator: Schaefer, T. & Shuryak, E.
Partner: UNT Libraries Government Documents Department

Three-Loop Superfiniteness of N=8 Supergravity

Description: We construct the three-loop four-point amplitude of N = 8 supergravity using the unitarity method. The amplitude is ultraviolet finite in four dimensions. Novel cancellations, not predicted by traditional superspace power-counting arguments, render its degree of divergence in D dimensions to be no worse than that of N = 4 super-Yang-Mills theory--a finite theory in four dimensions. Similar cancellations can be identified at all loop orders in certain unitarity cuts, suggesting that N = 8 supergravity may be a perturbatively finite theory of quantum gravity.
Date: February 20, 2007
Creator: Bern, Z.; Carrasco, J.J.; Dixon, L.J.; Johansson, H.; Kosower, D.A. & Roiban, R.
Partner: UNT Libraries Government Documents Department

Hyper-fast interstellar travel via a modification of spacetime geometry

Description: We analyze difficulties with proposals for hyper-fast interstellar travel via modifying the spacetime geometry, using as illustrations the Alcubierre warp drive and the Krasnikov tube. As it is easy to see, no violations of local causality or any other known physical principles are involved as far as motion of spacecrafts is concerned. However, the generation and support of the appropriate spacetime geometry configurations does create problems, the most significant of which are a violation of the weak energy condition, a violation of local causality, and a violation of the global causality protection. The violation of the chronology protection is the most serious of them as it opens a possibility of time travel. We trace the origin of the difficulties to the classical nature of the gravity field. This strongly indicates that hyper-fast interstellar travel should be transferred to the realm of a fully quantized gravitational theory. We outline an approach to further the research in this direction.
Date: August 1, 1997
Creator: Kheyfets, A. & Miller, W.A.
Partner: UNT Libraries Government Documents Department

Compton Scattering at the NLC and Large Extra Dimensions

Description: We study Compton scattering, {gamma}e {yields} {gamma}e, in the context of the recent proposal for Weak Scale Quantum Gravity (WSQG) with large extra dimensions. It is shown that, with an ultraviolet cutoff M{sub S} {approx} 1 TeV for the effective gravity theory, the cross section for this process at the Next Linear Collider (NLC) deviates from the prediction of the Standard Model significantly. Our results suggest that, for typical proposed NLC energies and luminosities, WSQG can be tested in the range 4 TeV {approx}< M{sub S} {approx}< 16 TeV, making {gamma}e {yields} {gamma}e an important test channel.
Date: July 20, 1999
Creator: Davoudiasl, Hooman
Partner: UNT Libraries Government Documents Department

Tests of Low Scale Quantum Gravity in e{sup -}e{sup -} and {gamma}{gamma} Collisions

Description: Arkani-Hamed, Dimopoulos and Dvali have recently proposed that gravity may become strong at energies near 1 TeV due to the existence of large extra dimensions thus ''removing'' the hierarchy problem. In this talk we examine the exchange of towers of Kaluza-Klein gravitons and their influence on Moller scattering as well as the production of pairs of massive gauge bosons in {gamma}{gamma}collisions. These tower exchanges lead to a set of new dimension-8 operators that can significantly alter the Standard Model expectations for these processes. In the case of {gamma}{gamma}collisions, the role of polarization for both the initial state photons and the final state gauge bosons in improving sensitivity to graviton exchange is emphasized.
Date: July 19, 1999
Creator: Rizzo, Thomas G.
Partner: UNT Libraries Government Documents Department

Gamma-Ray Burst Physics with GLAST

Description: The Gamma-ray Large Area Space Telescope (GLAST) is an international space mission that will study the cosmos in the energy range 10 keV-300 GeV, the upper end of which is one of the last poorly observed region of the celestial electromagnetic spectrum. The ancestor of the GLAST/LAT was the Energetic Gamma Ray Experiment Telescope (EGRET) detector, which flew onboard the Compton Gamma Ray Observatory (CGRO). The amount of information and the step forward that the high energy astrophysics made thanks to its 9 years of observations are impressive. Nevertheless, EGRET uncovered the tip of the iceberg, raising many questions, and it is in the light of EGRET's results that the great potential of the next generation gamma-ray telescope can be appreciated. GLAST will have an imaging gamma-ray telescope, the Large Area Telescope (LAT) vastly more capable than instruments own previously, as well as a secondary instrument, the GLAST Bursts Monitor, or GBM, to augment the study of gamma-ray bursts. Gamma-Ray Bursts (GRBs) science is one of the most exciting challenges for the GLAST mission, exploring the high energy emission of one of the most intense phenomena in the sky, shading light on various problems: from the acceleration of particles to the emission processes, to more exotic physics like Quantum Gravity effect. In this paper we report the work done so far in the simulation development as well as the study of the LAT sensitivity to GRB.
Date: October 6, 2006
Creator: Omodei, N. & /INFN, Pisa
Partner: UNT Libraries Government Documents Department

Scattering States in AdS/CFT

Description: We show that suitably regulated multi-trace primary states in large N CFTs behave like 'in' and 'out' scattering states in the flat-space limit of AdS. Their transition matrix elements approach the exact scattering amplitudes for the bulk theory, providing a natural CFT definition of the flat space S-Matrix. We study corrections resulting from the AdS curvature and particle propagation far from the center of AdS, and show that AdS simply provides an IR regulator that disappears in the flat space limit.
Date: February 14, 2012
Creator: Fitzpatrick, A.Liam; U., /Boston; Kaplan, Jared & /SLAC
Partner: UNT Libraries Government Documents Department

A New Principle in Physiscs: the Principle "Finiteness", and Some Consequences

Description: In this paper I propose a new principle in physics: the principle of "finiteness". It stems from the definition of physics as a science that deals (among other things) with measurable dimensional physical quantities. Since measurement results, including their errors, are always finite, the principle of finiteness postulates that the mathematical formulation of "legitimate" laws of physics should prevent exactly zero or infinite solutions. Some consequences of the principle of finiteness are discussed, in general, and then more specifically in the fields of special relativity, quantum mechanics, and quantum gravity. The consequences are derived independently of any other theory or principle in physics. I propose "finiteness" as a postulate (like the constancy of the speed of light in vacuum, "c"), as opposed to a notion whose validity has to be corroborated by, or derived theoretically or experimentally from other facts, theories, or principles.
Date: June 25, 2010
Creator: Sternlieb, Abraham
Partner: UNT Libraries Government Documents Department

Classical geometrical interpretation of ghost fields and anomalies in Yang-Mills theory and quantum gravity

Description: The reinterpretation of the BRS equations of Quantum Field Theory as the Maurer Cartan equation of a classical principal fiber bundle leads to a simple gauge invariant classification of the anomalies in Yang Mills theory and gravity.
Date: May 14, 1985
Creator: Thierry-Mieg, J.
Partner: UNT Libraries Government Documents Department