Search results for "gravity"
showing 10 items of 537 documents
Seasonal changes in sediment core PS1795-2
2014
The Weddell Sea and the associated Filchner-Rønne Ice Shelf constitute key regions for global bottomwater production today. However, little is known about bottom-water production under different climate and icesheet conditions. Therefore, we studied core PS1795, which consists primarily of fine-grained siliciclastic varves that were deposited on contourite ridges in the southeastern Weddell Sea during the Last Glacial Maximum (LGM). We conducted high-resolution X-ray fluorescence (XRF) analysis and grain-size measurements with the RADIUS tool (Seelos and Sirocko, 2005, doi:10.1111/j.1365-3091.2005.00715.x) using thin sections to characterize the two seasonal components of the varves at sub-…
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…
Observational signatures of Higgs inflation
2016
We investigate the dependency of Higgs inflation on the non-renormalisable matching between the low energy Standard Model limit and the inflationary regime at high energies. We show that for the top mass range $m_t \gtrsim 171.8$ GeV the scenario robustly predicts the spectral index $n_s \simeq 0.97$ and the tensor-to-scalar ratio $r\simeq 0.003$. The matching is however non-trivial, even the best-fit values $m_h=125.09$ GeV and $m_t=173.21$ GeV require a jump $\delta \lambda \sim 0.01$ in the Higgs coupling below the inflationary scale. For $m_t\lesssim 171.8$ GeV, the matching may generate a feature in the inflationary potential. In this case the predicted values of $n_s$ and $r$ vary but…
Search for resonant second generation slepton production at the Fermilab Tevatron
2006
Made available in DSpace on 2022-04-28T20:09:02Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-01-01 We present a search for supersymmetry in the R-parity violating resonant production and decay of smuons and muon sneutrinos in the channels, 2,3,40. We analyzed 0.38fb-1 of integrated luminosity collected between April 2002 and August 2004 with the D0 detector at the Fermilab Tevatron Collider. The observed number of events is in agreement with the standard model expectation, and we calculate 95% C.L. limits on the slepton production cross section times branching fraction to gaugino plus muon, as a function of slepton and gaugino masses. In the framework of minimal supergravity, we s…
Search for extra dimensions in diphoton events from proton-proton collisions at root s=7 TeV in the ATLAS detector at the LHC
2013
The large difference between the Planck scale and the electroweak scale, known as the hierarchy problem, is addressed in certain models through the postulate of extra spatial dimensions. A search for evidence of extra spatial dimensions in the diphoton channel has been performed using the full set of proton–proton collisions at √s = 7 TeV recorded in 2011 with the ATLAS detector at the CERN Large Hadron Collider. This dataset corresponds to an integrated luminosity of 4.9fb[superscript −1]. The diphoton invariant mass spectrum is observed to be in good agreement with the Standard Model expectation. In the context of the model proposed by Arkani–Hamed, Dimopoulos and Dvali, 95% confidence le…
Search for supersymmetry via associated production of charginos and neutralinos in final states with three leptons
2005
A search for associated production of charginos and neutralinos is performed using data recorded with the D0 detector at a ppbar center-of-mass energy of 1.96 TeV at the Fermilab Tevatron Collider. This analysis considers final states with missing transverse energy and three leptons, of which at least two are electrons or muons. No evidence for supersymmetry is found in a dataset corresponding to an integrated luminosity of 320 pb-1. Limits on the product of the production cross section and leptonic branching fraction are set. For the minimal supergravity model, a chargino lower mass limit of 117 GeV at the 95% C.L. is derived in regions of parameter space with enhanced leptonic branching f…
Gravity-induced liquid crystal phase transitions of colloidal platelets.
2004
he influence of gravity on a suspension of sterically stabilized colloidal gibbsite platelets is studied. An initially isotropic-nematic biphasic sample of such a suspension develops a columnar phase on the bottom on prolonged standing. This phenomenon is described using a simple osmotic compression model. We performed Monte Carlo simulations of cut spheres with aspect ratio L/D = 1/15 and took data from the literature to supply the equations of state required for the model. We find that the model describes the observed three-phase equilibrium quite well.
Structure and stability of traversable thin-shell wormholes in Palatini f(R) gravity
2020
We study the structure and stability of traversable wormholes built as (spherically symmetric) thin shells in the context of Palatini f(R) gravity. Using a suitable junction formalism for these theories we find that the effective number of degrees of freedom on the shell is reduced to a single one, which fixes the equation of state to be that of massless stress-energy fields, contrary to the general relativistic and metric f(R) cases. Another major difference is that the surface energy density threading the thin shell, needed in order to sustain the wormhole, can take any sign and may even vanish, depending on the desired features of the corresponding solutions. We illustrate our results by…
Relativistic Low Angular Momentum Accretion: Long Time Evolution of Hydrodynamical Inviscid Flows
2018
We investigate relativistic low angular momentum accretion of inviscid perfect fluid onto a Schwarzschild black hole. The simulations are performed with a general-relativistic, high-resolution (second-order), shock-capturing, hydrodynamical numerical code. We use horizon-penetrating Eddington-Finkelstein coordinates to remove inaccuracies in regions of strong gravity near the black hole horizon and show the expected convergence of the code with the Michel solution and stationary Fishbone-Moncrief toroids. We recover, in the framework of relativistic hydrodynamics, the qualitative behavior known from previous Newtonian studies that used a Bondi background flow in a pseudo-relativistic gravit…
Novel type of CPT violation for correlated Einstein-Podolsky-Rosen states of neutral mesons.
2004
We discuss modifications to the concept of an "antiparticle," induced by a breakdown of the CPT symmetry at a fundamental level, realized within an extended class of quantum gravity models. The resulting loss of particle-antiparticle identity in the neutral-meson system induces a breaking of the Einstein-Podolsky-Rosen correlation imposed by Bose statistics. This is parametrized by a complex parameter associated with the contamination by the "wrong symmetry" state. The physical consequences are studied, and novel observables of CPT violation in phi factories are proposed.