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ULTRAHIGH ENERGY NEUTRINOS, SMALL X AND UNITARITY.

Description: The ultrahigh energy cross section for neutrino interactions with nucleons is reviewed, and unitarity constraints are discussed. We argue that existing QCD extrapolations are self-consistent, and do not imply a breakdown of the perturbative expansion in the weak coupling.
Date: June 30, 2001
Creator: Hall Reno, M.; Sarcevic, I. N.; Sterman, G.; Stratmann, M. & Vogelsang, W.
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Partner: UNT Libraries Government Documents Department
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Ultraviolet Behavior of N = 8 supergravity

Description: In these lectures the author describes the remarkable ultraviolet behavior of N = 8 supergravity, which through four loops is no worse than that of N = 4 super-Yang-Mills theory (a finite theory). I also explain the computational tools that allow multi-loop amplitudes to be evaluated in this theory - the KLT relations and the unitarity method - and sketch how ultraviolet divergences are extracted from the amplitudes.
Date: June 7, 2010
Creator: Dixon, Lance J.
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Partner: UNT Libraries Government Documents Department
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Unexpected Cancellations in Gravity Theories

Description: Recent computations of scattering amplitudes show that N = 8 supergravity is surprisingly well behaved in the ultraviolet and may even be ultraviolet finite in perturbation theory. The novel cancellations necessary for ultraviolet finiteness first appear at one loop in the guise of the ''no-triangle hypothesis''. We study one-loop amplitudes in pure Einstein gravity and point out the existence of cancellations similar to those found previously in N = 8 supergravity. These cancellations go beyon… more
Date: July 13, 2007
Creator: Bern, Z.; Carrasco, J.J.; /UCLA; Forde, D.; /SLAC, /UCLA; Ita, H. et al.
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Partner: UNT Libraries Government Documents Department
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Unitarity and the Holographic S-Matrix

Description: The bulk S-Matrix can be given a non-perturbative definition in terms of the flat space limit of AdS/CFT. We show that the unitarity of the S-Matrix, ie the optical theorem, can be derived by studying the behavior of the OPE and the conformal block decomposition in the flat space limit. When applied to perturbation theory in AdS, this gives a holographic derivation of the cutting rules for Feynman diagrams. To demonstrate these facts we introduce some new techniques for the analysis of conforma… more
Date: August 28, 2012
Creator: Fitzpatrick, A.Liam; /Stanford U., Phys. Dept. & Kaplan, Jared
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Partner: UNT Libraries Government Documents Department
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Unitarity Bounds and RG Flows in Time Dependent Quantum Field Theory

Description: We generalize unitarity bounds on operator dimensions in conformal field theory to field theories with spacetime dependent couplings. Below the energy scale of spacetime variation of the couplings, their evolution can strongly affect the physics, effectively shifting the infrared operator scaling and unitarity bounds determined from correlation functions in the theory. We analyze this explicitly for large-N double-trace flows, and connect these to UV complete field theories. One motivating clas… more
Date: April 5, 2012
Creator: Dong, Xi; Horn, Bart; Silverstein, Eva; Torroba, Gonzalo & /Stanford U., ITP /Stanford U., Phys. Dept. /SLAC
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Unitarity Constraints on Asymmetric Freeze-In

Description: This paper considers unitarity and CPT constraints on asymmetric freeze-in, the use of freeze-in to store baryon number in a dark sector. In this scenario, Sakharov's out of equilibrium condition is satisfied by placing the visible and hidden sectors at different temperatures while a net visible baryon number is produced by storing negative baryon number in a dark sector. It is shown that unitarity and CPT lead to unexpected cancellations. In particular, the transfer of baryon number cancels co… more
Date: August 15, 2011
Creator: Hook, Anson
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Partner: UNT Libraries Government Documents Department
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Unitarity of the Bencze--Redish--Sloan Equations

Description: It is shown that the N-particle scattering equations of Bencze, Redish and Sloan satisfy a proper unitarity relation. The proof uses a recently proposed form of these equations given by Benoist-Gueutal, L'Huillier, Redish and Tandy.
Date: May 1978
Creator: Polyzou, Wayne
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Unitarity restrictions on semi-classical approximations to certain functional integrals

Description: Estimates of physically relevant quantities (cross sections, multiplicities, correlations) in eikonal models of high-energy field theories lead to a class of semiclassical solutions to nonlinear Euler equations. The requirement of unitarity restricts these possible solutions to a unique function of energy and impact parameter.
Date: January 1, 1978
Creator: Fried, H. M.
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Partner: UNT Libraries Government Documents Department
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Unitarity Triangle Angle Measurements at BaBar

Description: We present recent results of measurements of the Unitarity Triangle angles alpha, beta and gamma made with the BaBar detector at the PEP-II asymmetric B factory. We present recent results of measurements of the Unitarity Triangle angles alpha, beta and gamma made with the BaBar detector at the PEP-II asymmetric B factory.
Date: June 30, 2005
Creator: Latham, Thomas E.
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Partner: UNT Libraries Government Documents Department
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Update on Angles and Sides of the CKM Unitarity Triangle from BaBar

Description: We report several recent updates from the BABAR Collaboration on the matrix elements |V{sub cb}|, |V{sub ub}|, and |V{sub td}| of the Cabibbo-Kobayashi-Maskawa (CKM) quark-mixing matrix, and the angles {beta} and {alpha} of the unitarity triangle. Most results presented here are using the full BABAR {Upsilon}(4S) data set.
Date: November 14, 2011
Creator: Cheng, Chih-hsiang & /Caltech
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Partner: UNT Libraries Government Documents Department
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Updated Measurement of the CKM Angle alpha Using B0->rho+rho- Decays

Description: The authors present results from an analysis of B{sup 0} {yields} {rho}{sup +}{rho}{sup -} using 316 fb{sup -1} of {Upsilon}(4S) {yields} B{bar B} decays observed with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. They measure the B{sup 0} {yields} {rho}{sup +}{rho}{sup -} branching fraction, longitudinal polarization fraction f{sub L}, and the CP-violating parameters S{sub long} and C{sub long}: {Beta}(B{sup 0} {yields} {rho}{sup +}{rho}{sup -}) = (23.5 {+-} 2.2(stat) {… more
Date: September 26, 2006
Creator: Aubert, B.
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Partner: UNT Libraries Government Documents Department
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Use of R-matrix methods for light element evaluations

Description: Some general aspects of parameterizing nuclear reaction data with a unitary, multichannel theory are discussed. The special case of R-matrix theory are discussed. The special case of R-matrix theory is considered, where the explicit separation of long- and short-range forces and the natural occurrence of energy pole terms afford a number of advantages in describing data for light-element reactions. Examples are given for both neutron- and charged-particle-induced reactions which illustrate mult… more
Date: January 1, 1980
Creator: Hale, G.M.
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Partner: UNT Libraries Government Documents Department
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The VIIth Blois workshop: Theory summary and factorization issues

Description: Theory presentations at this workshop have covered a wide range of topics. In addition to the traditional topics of elastic and diffractive scattering, the workshop has had a variety of interesting talks coming under the broad umbrella of ``Recent Advances in Hadron Physics.`` These have included review talks on lattice gauge theory, techniques for high-order perturbative QCD calculations, strong interaction effective field theories, the current status of QED and the construction of theories be… more
Date: September 17, 1997
Creator: White, A.R.
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Partner: UNT Libraries Government Documents Department
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Weak interaction studies with an on-line Penning trap mass spectrometer.

Description: Superallowed {beta}-decays are a sensitive probe of the fundamental aspects of the weak interaction. Such decays are used to stringently test the CVC hypothesis, deduce a precise value of the weak vector coupling constant, test the unitarity of the CKM matrix and look for deviation from the V-A structure for the weak interaction. The ability to efficiently capture and store short-lived superallowed beta-emitters in ion traps will help to elucidate discrepancies in the most precise unitarity tes… more
Date: March 10, 1999
Creator: Barber, R. C.; Buchinger, F.; Crawford, J. E.; Feng, X.; Gulick, S.; Hackman, G. et al.
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Partner: UNT Libraries Government Documents Department
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Wilson lines and symmetry breaking on orbifolds

Description: Gauge symmetry breaking by boundary conditions on a manifold is known to be equivalent to Wilson-line breaking through a background gauge field, and is therefore spontaneous. These equivalent pictures are related by a non-periodic gauge transformation. However, we find that boundary condition gauge symmetry breaking on orbifolds is explicit; there is no gauge where all the breaking can be attributed to a background gauge field. In the case of a five-dimensional SU(5) grand unified theory on S{s… more
Date: August 16, 2002
Creator: Hall, Lawrence J.; Murayama, Hitoshi & Nomura, Yasunori
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Partner: UNT Libraries Government Documents Department
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