11,344 research outputs found
Awake remembrance of these valiant dead : Henry V and the politics of the English history play
'A PROPAGANDA-PLAY on National Unity: heavily orchestrated for the brass' was how A. P. Rossiter summed up Henry V in 1954. (1) The assumption that this play is complicit with the promonarchical, nationalist rhetoric of the Chorus, and with the particular myth of Englishness it propounds, has persisted. In recent years the most cogent articulation of this view has come from Richard Helgerson, who sees the play as the culmination of Shakespeare's gradual tightening of his "obsessive and compelling focus on the ruler" during the writing of his English history cycle, at the cost of occluding the interests of the ruled
A Variable-Flavour Number Scheme for NNLO
At NNLO it is particularly important to have a Variable-Flavour Number Scheme
(VFNS) to deal with heavy quarks because there are major problems with both the
zero mass variable-flavour number scheme and the fixed-flavour number scheme. I
illustrate these problems and present a general formulation of a
Variable-Flavour Number Scheme (VFNS)for heavy quarks that is explicitly
implemented up to NNLO in the strong coupling constant alpha_S, and may be used
in NNLO global fits for parton distributions. The procedure combines elements
of the ACOT(chi) scheme and the Thorne-Roberts scheme. Despite the fact that at
NNLO the parton distributions are discontinuous as one changes the number of
active quark flavours, all physical quantities are continuous at flavour
transitions and the comparison with data is successful.Comment: 17 pages, 5 figures included as .ps files, uses axodraw. One
additional explanatory sentence after eq. (25). Correction of typos and
updated references. To be published in Phys. Rev.
Parton distributions for LO generators
We present a study of the results obtained combining LO partonic matrix
elements with either LO or NLO partons distributions. These are compared to the
best prediction using NLO for both matrix elements and parton distributions.
The aim is to determine which parton distributions are most appropriate to use
in those cases where only LO matrix elements are available, e.g. as in many
Monte Carlo generators. Both LO and NLO parton distributions have flaws,
sometimes serious, for some processes, so a modified optimal LO set is
suggested. We investigate a wide variety of process, and the LO* pdf works at
least as well as, and often better than, both LO and NLO pdfs in nearly all
cases.The LO* pdf set is now available in the LHAPDF package
Seismic gravity-gradient noise in interferometric gravitational-wave detectors
When ambient seismic waves pass near and under an interferometric gravitational-wave detector, they induce density perturbations in the Earth, which in turn produce fluctuating gravitational forces on the interferometer’s test masses. These forces mimic a stochastic background of gravitational waves and thus constitute a noise source. This seismic gravity-gradient noise has been estimated and discussed previously by Saulson using a simple model of the Earth’s ambient seismic motions. In this paper, we develop a more sophisticated model of these motions, based on the theory of multimode Rayleigh and Love waves propagating in a multilayer medium that approximates the geological strata at the LIGO sites, and we use this model to reexamine seismic gravity gradients. We characterize the seismic gravity-gradient noise by a transfer function, T(f )≡x̃(f )/W̃(f ), from the spectrum of rms seismic displacements averaged over vertical and horizontal directions, W̃(f ), to the spectrum of interferometric test-mass motions, x̃(f )≡Lh̃(f ); here L is the interferometer arm length, h̃(f ) is the gravitational-wave noise spectrum, and f is frequency. Our model predicts a transfer function with essentially the same functional form as that derived by Saulson, T≃4πGρ(2πf )-2β(f ), where ρ is the density of Earth near the test masses, G is Newton’s constant, and β(f )≡γ(f )Γ(f )β′(f ) is a dimensionless reduced transfer function whose components γ≃1 and Γ≃1 account for a weak correlation between the interferometer’s two corner test masses and a slight reduction of the noise due to the height of the test masses above the Earth’s surface. This paper’s primary foci are (i) a study of how β′(f )≃β(f ) depends on the various Rayleigh and Love modes that are present in the seismic spectrum, (ii) an attempt to estimate which modes are actually present at the two LIGO sites at quiet times and at noisy times, and (iii) a corresponding estimate of the magnitude of β′(f ) at quiet and noisy times. We conclude that at quiet times β′≃0.35–0.6 at the LIGO sites, and at noisy times β′≃0.15–1.4. (For comparison, Saulson’s simple model gave β=β′=1/sqrt[3]=0.58.) By folding our resulting transfer function into the “standard LIGO seismic spectrum,” which approximates W̃(f ) at typical times, we obtain the gravity-gradient noise spectra. At quiet times this noise is below the benchmark noise level of “advanced LIGO interferometers” at all frequencies (though not by much at ∼10 Hz); at noisy times it may significantly exceed the advanced noise level near 10 Hz. The lower edge of our quiet-time noise constitutes a limit, beyond which there would be little gain from further improvements in vibration isolation and thermal noise, unless one can also reduce the seismic gravity gradient noise. Two methods of such reduction are briefly discussed: monitoring the Earth’s density perturbations near each test mass, computing the gravitational forces they produce, and correcting the data for those forces; and constructing narrow moats around the interferometers’ corner and end stations to shield out the fundamental-mode Rayleigh waves, which we suspect dominate at quiet times
The relativistic equations of stellar structure and evolution. Stars with degenerate neutron cores. 1: Structure of equilibrium models
The general relativistic equations of stellar structure and evolution are reformulated in a notation which makes easy contact with Newtonian theory. Also, a general relativistic version of the mixing-length formalism for convection is presented. Finally, it is argued that in previous work on spherical systems general relativity theorists have identified the wrong quantity as "total mass-energy inside radius r.
Inclusion of new LHC data in MMHT PDFs
I consider the effects of including a variety of new LHC data sets into the
MMHT approach for PDF determination. I consider the impact of fitting new LHC
and Tevatron data, which leads to clear improvements in some PDF uncertainties.
There are specific issues with ATLAS 7 TeV jet data and I include a discussion
of the treatment of correlated uncertainties and briefly the effects of NNLO
corrections. I also present preliminary results with the inclusion of the high
precison final ATLAS 7 TeV rapidity-dependent data.Comment: 6 pages. To appear in proceedings of DIS2017 Worksho
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