7,340 research outputs found
Scattering theory for quantum fields with indefinite metric
In this work, we discuss the scattering theory of local, relativistic quantum
fields with indefinite metric. Since the results of Haag--Ruelle theory do not
carry over to the case of indefinite metric, we propose an axiomatic framework
for the construction of in- and out- states, such that the LSZ asymptotic
condition can be derived from the assumptions. The central mathematical object
for this construction is the collection of mixed vacuum expectation values of
local, in- and out- fields, called the ``form factor functional'', which is
required to fulfill a Hilbert space structure condition. Given a scattering
matrix with polynomial transfer functions, we then construct interpolating,
local, relativistic quantum fields with indefinite metric, which fit into the
given scattering framework
A closed-form formula for pricing bonds between coupon payments
We derive a closed-form formula for computing bond prices between coupon payments. Our results cover both the `Treasury' and the `Street' pricing methods used by sovereign and corporate issuers. We apply our formulas to two UK gilts, the 8% Treasury Gilt 2015, and the 0.5% Treasury Gilt 2022, and show that we can obtain the dirty price of these bonds at any date with a minimum of calculations, and without intensive computational resources
EventKG+BT: Generation of Interactive Biography Timelines from a Knowledge Graph
Research on notable accomplishments and important events in the life of
people of public interest usually requires close reading of long encyclopedic
or biographical sources, which is a tedious and time-consuming task. Whereas
semantic reference sources, such as the EventKG knowledge graph, provide
structured representations of relevant facts, they often include hundreds of
events and temporal relations for particular entities. In this paper, we
present EventKG+BT - a timeline generation system that creates concise and
interactive spatio-temporal representations of biographies from a knowledge
graph using distant supervision.Comment: ESWC 2020 Satellite Events pp 91-9
From Black Wednesday to Brexit: macroeconomic shocks and correlations of equity returns in France, Germany, Italy, Spain, and the United Kingdom
This paper investigates whether macroeconomic shocks, such as the UK's referendum decision to leave the European Union (“Brexit”), the 2008 Financial Crisis, the 1992 ERM Crisis (“Black Wednesday”), and the 1987 stock market crash (“Black Monday”), had a positive impact on portfolio risk diversification. We estimate weekly dynamic conditional correlations and then optimal sectoral portfolio allocations between 1973 and 2019. Our results show that correlations of equity returns increased as a consequence of economic integration among European countries from the mid-1980s until the late 2000s, and decreased in the United Kingdom after Black Wednesday and the Brexit referendum. We tested the existence of a correlation change-point on June 27, 2016 by applying Wied et al. (2012)'s [Econometric Theory, 28(3), 570–589] correlation structural break test, which we modified to account for dynamic conditional correlations. Application of this test confirms that the referendum date was a break-point in nearly all UK manufacturing industries. The failure of Lehman Brothers and the 1987 stock market crash were also identified as structural breaks in equity correlations. Moreover, our findings suggest that the Brexit vote may constitute a long-term trend reversal of the convergence of equity return correlations in European markets, akin to Black Wednesday, rather than a shock like the 1987 and 2008 financial crises, which merely intensified a historical upward trend in correlations of European equity returns
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