Search results for "gravity model"

Estimating the Effect of Common Currencies on Trade: Blooming or Withering Roses?

2013

Abstract Using a gravity model and data on 182 countries worldwide, this paper estimates the effects of exchange rate volatility and currency unions on international trade for ten years spanning 1980 through 2010. We provide added confirmation and further strengthen the empirical findings in Rose (2000) prior to 1999, but we find a gradually diminishing Rose effect for the 2000-2010 period, when the Euro Zone is added to the currency union dummy. The rest of the coefficients generally comply in magnitude and sign with what is standard in the “gravity” literature. Our findings support a much stronger effect of a currency union on trade than the hypothetical effect of reducing exchange rate v…

The euro impact on trade. Long run evidence with structural breaks

2012

In this paper we present new evidence on the euro effect on trade. We use a data set containing all bilateral combinations in a panel of 26 OECD countries during the period 1967-2008. From a methodological point of view, we implement a new generation of tests that allow solving some of the problems derived from the non-stationary nature of the data. To this aim we apply panel tests that account for the presence of cross-section dependence as well as discontinuities in the non-stationary panel data. We test for cointegration between the variables using panel cointegration tests, especially the ones proposed by Banerjee and Carrióni- Silvestre (2010). We also efficiently estimate the long-run…

Holographic duals of 6d RG flows

2018

A notable class of superconformal theories (SCFTs) in six dimensions is parameterized by an integer $N$, an ADE group $G$, and two nilpotent elements $\mu_\mathrm{L,R}$ in $G$. Nilpotent elements have a natural partial ordering, which has been conjectured to coincide with the hierarchy of renormalization-group flows among the SCFTs. In this paper we test this conjecture for $G=\mathrm{SU}(k)$, where AdS$_7$ duals exist in IIA. We work with a seven-dimensional gauged supergravity, consisting of the gravity multiplet and two $\mathrm{SU}(k)$ non-Abelian vector multiplets. We show that this theory has many supersymmetric AdS$_7$ vacua, determined by two nilpotent elements, which are naturally …

The geometry of N=3 AdS4 in massive IIA

2018

The geometry of the ${\cal N} = 3$, SO(4)--invariant, AdS$_4$ solution of massive type IIA supergravity that uplifts from the ${\cal N} = 3 $ vacuum of $D=4$ ${\cal N} = 8$ dyonic ISO(7) supergravity is investigated. Firstly, a $D=4$, SO(4)--invariant restricted duality hierarchy is constructed and used to uplift the entire, dynamical SO(4)--invariant sector to massive type IIA. The resulting consistent uplift formulae are used to obtain a new local expression for the ${\cal N} = 3 $ AdS$_4$ solution in massive IIA and analyse its geometry. Locally, the internal $S^6$ geometry corresponds to a warped fibration of $S^2$ and a hemisphere of $S^4$. This can be regarded as a warped generalisati…

The two-loop five-particle amplitude in $\mathcal{N}=8$ supergravity

2019

We compute for the first time the two-loop five-particle amplitude in $\mathcal{N}=8$ supergravity. Starting from the known integrand, we perform an integration-by-parts reduction and express the answer in terms of uniform weight master integrals. The latter are known to evaluate to non-planar pentagon functions, described by a 31-letter symbol alphabet. We express the final result for the amplitude in terms of uniform weight four symbols, multiplied by a small set of rational factors. The amplitude satisfies the expected factorization properties when one external graviton becomes soft, and when two external gravitons become collinear. We verify that the soft divergences of the amplitude ex…

Institutional Quality and International Competitiveness

2008

Is the ‘euro effect’ on trade so small after all? New evidence using gravity equations with panel cointegration techniques

2014

In this paper we present new evidence on the aggregate effect of the euro on trade using data for 26 OECD countries for the period 1967–2008. We strive to fill the gaps present in the previous literature through a second-generation panel cointegration tests and estimators that account for both cross-section dependence in the data and discontinuities in the deterministic and the cointegrating vector in the time dimension. This approach allows us to put the adoption of the euro by EMU members in historical perspective. We argue that the creation of the EMU is best interpreted as a progression of policy changes. Once we control for all of them the euro effect decreases considerably but is stil…

The euro impact on trade: long run evidence with structural breaks

2012

In this paper we present new evidence on the euro effect on trade. We use a data set containing all bilateral combinations in a panel of 26 OECD countries during the period 1967-2008. From a methodological point of view, we implement a new generation of tests that allow solving some of the problems derived from the non-stationary nature of the data. To this aim we apply panel tests that account for the presence of cross-section dependence as well as discontinuities in the non-stationary panel data. We test for cointegration between the variables using panel cointegration tests, especially the ones proposed by Banerjee and Carrióni- Silvestre (2010). We also efficiently estimate the long-run…

Correspondence between modified gravity and general relativity with scalar fields

2018

We describe a novel procedure to map the field equations of nonlinear Ricci-based metric-affine theories of gravity, coupled to scalar matter described by a given Lagrangian, into the field equations of General Relativity coupled to a different scalar field Lagrangian. Our analysis considers examples with a single and $N$ real scalar fields, described either by canonical Lagrangians or by generalized functions of the kinetic and potential terms. In particular, we consider several explicit examples involving $f(R)$ theories and the Eddington-inspired Born-Infeld gravity model, coupled to different scalar field Lagrangians. We show how the nonlinearities of the gravitational sector of these t…

First-order flows and stabilisation equations for non-BPS extremal black holes

2011

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