Fit to the Bjorken, Ellis-Jaffe and Gross-Llewellyn-Smith sum rules in a renormalon based approach

We study the large order behaviour in perturbation theory of the Bjorken, Ellis-Jaffe and Gross-Llewellyn-Smith sum rules. In particular, we consider their first infrared renormalons, for which we obtain their analytic structure with logarithmic accuracy and also an approximate determination of their normalization constant. Estimates of higher order terms of the perturbative series are given. The Renormalon subtracted scheme is worked out for these observables and compared with experimental data. Overall, good agreement with experiment is found. This allows us to obtain {\hat a}_0 and some higher-twist non-perturbative constants from experiment: {\hat a}_0=0.141\pm 0.089; f_{3,RS}(1 GeV)=-0.124^{+0.137}_{-0.142} GeV^2.Comment: 23 pages, 18 figures, one reference added, journal versio

How Hertzian solitary waves interact with boundaries in a 1-D granular medium

We perform measurements, numerical simulations, and quantitative comparisons with available theory on solitary wave propagation in a linear chain of beads without static preconstrain. By designing a nonintrusive force sensor to measure the impulse as it propagates along the chain, we study the solitary wave reflection at a wall. We show that the main features of solitary wave reflection depend on wall mechanical properties. Since previous studies on solitary waves have been performed at walls without these considerations, our experiment provides a more reliable tool to characterize solitary wave propagation. We find, for the first time, precise quantitative agreements.Comment: Proof corrections, ReVTeX, 11 pages, 3 eps (Focus and related papers on http://www.supmeca.fr/perso/jobs/

Double fermiophobic Higgs boson production at the LHC and LC

We consider the phenomenology of a fermiophobic Higgs boson (h_f) at the Large Hadron Collider (LHC) and a e+e- Linear Collider (LC). At both machines the standard production mechanisms which rely on the coupling h_fVV (V=W,Z) can be very suppressed at large tan beta. In such cases the complementary channels pp to H^\pm h_f, A^0 h_f and e+e- to A^0 h_f offer promising cross-sections. Together with the potentially large branching ratios for H^\pm to h_fW* and A^0 to h_fZ*, these mechanisms would give rise to double h_f production, leading to signatures of gamma gamma gamma gamma, gamma gamma VV and VVVV.Comment: 19 pages, 9 figures, expanded discussion, fig.1 changed slightly, version to appear in Phys.Rev.

Resistance to eyespot (Pseudocercosporella herpotricoides) and distribution of biochemical markers in hexaploid lines derived from double cross (Triticum turgidum x Aegilops ventricosa) x T. aestivum

There are not good intraspecific sources of resistance to the eyespot disea se of wheat, aaused by Cercosporella herpotrichoides Fvon . The -ínterspecifia transfer of genes for resistanoe from Aegitops ventricosa into hexaploid wheat has been only partially achieved, because the degree of resistanoe attained is not as high as that of the donor. We report here on the transfer of resistanoe in a double oross (Triticum turgidum var. rubroatrwv H-1-1 x Ae.ventricosa AP-D x T.aestivum cv. Almatense H-10-15. The high level of resistanoe in a high proportion of the lines strongly suggests a simple genetic control for this oharacter (possibly by one major gene). The gene(s) responsible for resistanoe in the selected lines must be associa ted with the D genome of Aegilops ventricosa on the basis of a detailed study of the distribution of biochemioal markers in the H-93 lines. These results do not exelude that genes with similar effeets might be looated in the M° genome

Geometric structures on loop and path spaces

Is is known that the loop space associated to a Riemannian manifold admits a quasi-symplectic structure. This article shows that this structure is not likely to recover the underlying Riemannian metric by proving a result that is a strong indication of the "almost" independence of the quasi-symplectic structure with respect to the metric. Finally conditions to have contact structures on these spaces are studied.Comment: Final version. To appear in Proceedings of Math. Sci. Indian Academy of Science

Parameter space of experimental chaotic circuits with high-precision control parameters

ACKNOWLEDGMENTS The authors thank Professor Iberê Luiz Caldas for the suggestions and encouragement. The authors F.F.G.d.S., R.M.R., J.C.S., and H.A.A. acknowledge the Brazilian agency CNPq and state agencies FAPEMIG, FAPESP, and FAPESC, and M.S.B. also acknowledges the EPSRC Grant Ref. No. EP/I032606/1.Peer reviewedPublisher PD

Experimental evidence of solitary wave interaction in Hertzian chains

We study experimentally the interaction between two solitary waves that approach one to another in a linear chain of spheres interacting via the Hertz potential. When these counter propagating waves collide, they cross each other and a phase shift respect to the noninteracting waves is introduced, as a result of the nonlinear interaction potential. This observation is well reproduced by our numerical simulations and it is shown to be independent of viscoelastic dissipation at the beads contact. In addition, when the collision of equal amplitude and synchronized counter propagating waves takes place, we observe that two secondary solitary waves emerge from the interacting region. The amplitude of secondary solitary waves is proportional to the amplitude of incident waves. However, secondary solitary waves are stronger when the collision occurs at the middle contact in chains with even number of beads. Although numerical simulations correctly predict the existence of these waves, experiments show that their respective amplitude are significantly larger than predicted. We attribute this discrepancy to the rolling friction at the beads contacts during solitary wave propagation

The Double-Lined Spectrum of LBV 1806-20

Despite much theoretical and observational progress, there is no known firm upper limit to the masses of stars. Our understanding of the interplay between the immense radiation pressure produced by massive stars in formation and the opacity of infalling material is subject to theoretical uncertainties, and many observational claims of ``the most massive star'' have failed the singularity test. LBV 1806-20 is a particularly luminous object, L~10^6 Lsun, for which some have claimed very high mass estimates (M_initial>200 Msun), based, in part, on its similarity to the Pistol Star. We present high-resolution near-infrared spectroscopy of LBV 1806-20, showing that it is possibly a binary system with components separated in velocity by ~70 kms. If correct, then this system is not the most massive star known, yet it is a massive binary system. We argue that a binary, or merged, system is more consistent with the ages of nearby stars in the LBV 1806-20 cluster. In addition, we find that the velocity of V_LSR=36 kms is consistent with a distance of 11.8 kpc, a luminosity of 10^6.3 Lsun, and a system mass of ~130 Msun.Comment: ApJL, accepte