A Method to Determine ∣Vcb∣|V_{cb}| at the Weak Scale in Top Decays at the LHC

Until now, the Cabibbo Kobayashi Maskawa matrix element, $|V_{cb}|$, has always been measured in $B$ decays, i.e.~at an energy scale $q_b\sim \frac{m_b}{2}$, far below the weak scale. We consider here the possibility of measuring it close to the weak scale, at $q_W\sim m_W$, in top decays at the Large Hadron Collider (LHC). Our proposed method would use data from the LHC experiments in hadronic top decays $t\rightarrow bW\rightarrow b\overline{b} c$, tagged by the semileptonic decay of the associated top. We estimate the uncertainty of such a measurement, as a function of present and potential future experimental jet flavour-tagging performances, and conclude that first measurements using the data collected during 2016 - 2018 could yield a fractional error on \Vcb\ of order 7\% per experiment. We also give projected performances at higher luminosities, which could yield sensitivity to any Standard Model running of \Vcb\ below the weak scale, if present.Comment: 15 pages, 1 figures. Changes for V3: removed earlier Fig. 1, associated text and citations, added one new citatio

Ownership versus Environment: Why are Public Sector Firms Inefficient?

In this paper we disentangle the sources of public sector inefficiency using 1982-1995 panel data on manufacturing firms in Indonesia. We consider two leading hypotheses: (1) public sector enterprises are inefficient due to monitoring problems and (2) public sector enterprises are inefficient because of the environment in which they operate, as measured by the soft budget constraint. The two models are nested in a production function framework and the empirical results provide support for the second hypothesis. Public sector enterprises are inefficient because of their access to soft loans; public sector ownership has no independent impact on productivity growth. The finding that ownership per se does not matter, but environment does, holds when we control for fixed effects and when we allow for the endogeneity of government loans. Interestingly, private sector firms with access to government loans did not perform more poorly than other private sector enterprises. Another dimension of the environment, i.e. import penetration, also matters; public sector enterprises that have been shielded from import competition are inferior performers.

Ownership versus environment : disentangling the sources of public sector inefficiency

The authors compare the performance of public and private sector manufacturing firms in Indonesia for 1981-95. They analyze whether public sector inefficiency is due primarily to agency-type problems ("ownership") or to the business environment in which public enterprises operate, as measured by soft budget constraints or barriers to competition. They nest the two alternatives in a production function framework. The results, obtained from fixed-effects specifications, provide support for both models. The business environment matters. Only public enterprises that received loans from state banks or those shielded from import competition performed worse than private enterprises. Ownership matters. For a given level of import competition or soft loans, public enterprises perform worse than their counterparts in the private sector. Eliminating soft loans to Indonesia's public enterprises would raise total factor productivity by 6 percentage points; the same result could be achieved by increasing import penetration by 15 percentage points. The authors show that these findings are not due to selection effects for either privatization or the receipt of soft loans.Labor Policies,Banks&Banking Reform,Municipal Financial Management,Environmental Economics&Policies,Economic Theory&Research,Banks&Banking Reform,Municipal Financial Management,Environmental Economics&Policies,Economic Theory&Research,Public Sector Economics&Finance

Quantum mechanical scattering investigation of the thermionic and field induced emission components of the dark current in quantum well infrared photodetectors

The thermionic emission and field induced emission components of the dark current in quantum well infrared photodetectors are investigated using a quantum mechanical scattering theory approach. Calculations are performed for an experimentally reported device. Using this as a standard, the device dimensions were altered in order to increase its detection wavelength to cover the mid- (MIR) and far-infrared (FIR) regions of the spectrum. The behavior of the scattering mechanisms that contribute to the thermionic emission and field induced emission components were studied. The results highlight the change in the dominating scattering mediator across the MIR and FIR bands. © 2002 American Institute of Physics

T-111 Rankine system corrosion test loop, volume 2

For abstract, see N76-18258

The development of structural adhesive systems suitable for use with liquid oxygen /LOX/ Summary report, 20 Jun. 1969 - 19 Apr. 1970

Development of structural adhesive systems suitable for use with liquid oxyge

Wrinkling in engineering fabrics: a comparison between two different comprehensive modelling approaches

We consider two ‘comprehensive’ modelling approaches for engineering fabrics. We distinguish the two approaches using the terms ‘semi-discrete’ and ‘continuum’, reflecting their natures. We demonstrate a fitting procedure, used to identify the constitutive parameters of the continuum model from predictions of the semi-discrete model, the parameters of which are in turn fitted to experimental data. We, then, check the effectiveness of the continuum model by verifying the correspondence between semi-discrete and continuum model predictions using test cases not previously used in the identification process. Predictions of both modelling approaches are compared against full-field experimental kinematic data, obtained using stereoscopic digital image correlation techniques, and also with measured force data. Being a reduced order model and being implemented in an implicit rather than an explicit finite-element code, the continuum model requires significantly less computational power than the semi-discrete model and could therefore be used to more efficiently explore the mechanical response of engineering fabrics

The extensive nature of group quality

We consider groups of interacting nodes engaged in an activity as many-body, complex systems and analyse their cooperative behaviour from a mean-field point of view. We show that inter-nodal interactions rather than accumulated individual node strengths dominate the quality of group activity, and give rise to phenomena akin to phase transitions, where the extensive relationship between group quality and quantity reduces. The theory is tested using empirical data on quantity and quality of scientific research groups, for which critical masses are determined.Comment: 6 pages, 6 figures containing 13 plots. Very minor changes to coincide with published versio

Using aircraft measurements to determine the refractive index of Saharan dust during the DODO Experiments

Much uncertainty in the value of the imaginary part of the refractive index of mineral dust contributes to uncertainty in the radiative effect of mineral dust in the atmosphere. A synthesis of optical, chemical and physical in-situ aircraft measurements from the DODO experiments during February and August 2006 are used to calculate the refractive index mineral dust encountered over West Africa. Radiative transfer modeling and measurements of broadband shortwave irradiance at a range of altitudes are used to test and validate these calculations for a specific dust event on 23 August 2006 over Mauritania. Two techniques are used to determine the refractive index: firstly a method combining measurements of scattering, absorption, size distributions and Mie code simulations, and secondly a method using composition measured on filter samples to apportion the content of internally mixed quartz, calcite and iron oxide-clay aggregates, where the iron oxide is represented by either hematite or goethite and clay by either illite or kaolinite. The imaginary part of the refractive index at 550 nm (ni550) is found to range between 0.0001 i to 0.0046 i, and where filter samples are available, agreement between methods is found depending on mineral combination assumed. The refractive indices are also found to agree well with AERONET data where comparisons are possible. ni550 is found to vary with dust source, which is investigated with the NAME model for each case. The relationship between both size distribution and ni550 on the accumulation mode single scattering albedo at 550 nm (ω0550) are examined and size distribution is found to have no correlation to ω0550, while ni550 shows a strong linear relationship with ω0550. Radiative transfer modeling was performed with different models (Mie-derived refractive indices, but also filter sampling composition assuming both internal and external mixing). Our calculations indicate that Mie-derived values of ni550 and the externally mixed dust where the iron oxide-clay aggregate corresponds to the goethite-kaolinite combination result in the best agreement with irradiance measurements. The radiative effect of the dust is found to be very sensitive to the mineral combination (and hence refractive index) assumed, and to whether the dust is assumed to be internally or externally mixed