Higgs couplings and BSM physics: Run I Legacy constraints

We consider the Higgs boson decay processes and its production including all Run I results, through a parametrisation tailored for testing models of new physics beyond the Standard Model, and complementary to the one used by the LHC working groups. Different formalisms allow to best address different aspects of the Higgs boson physics. The choice of a particular parametrisation depends on a non-obvious balance of quantity and quality of the available experimental data, envisaged purpose for the parametrisation and degree of model independence, importance of the radiative corrections, and scale at which new particles appear explicitly in the physical spectrum. The most refined constraints can only be obtained by the experimental collaborations at present, as information about correlation between the various uncertainties on the different decay modes is not completely available in the public domain. It is therefore important that different approaches are considered and that the most detailed information is made available to allow testing the different aspects of the Higgs boson physics and the possible hints of physics beyond the Standard Model.Comment: 11 pages, 5 figure

Secular cooling of the solid Earth, emergence of the continents, and evolution of Earth's external envelopes

The secular cooling of the mantle and of the continental lithosphere trigger an increase in the area of emerged land. The corollary increase in weathering and erosion processes has major consequences for the evolution of Earth's external envelopes. We developed a physical model to evaluate the area of emerged land as a function of mantle temperature, continental area, and of the distribution of continental elevations. Our numerical results show that less than 15% of Earth's surface consisted of emerged land by the end of the Archaean. This is consistent with many geological and geochemical observations. To estimate the secular cooling of the continental lithosphere, we combined thermo-mechanical models with fi eld observations. Our results, constrained by geological data, suggest that the Moho temperature has decreased by ~ 200ºC over 2.7 Ga in the Pilbara Craton. To evaluate the eff ect of continental growth on the evolution of the area of emerged land, we developed a model based on published thermal evolution models. Our results suggest that the area of emerged land was less than 5% of Earth's surface in the Archaean, and that it does not depend on crustal growth. This allows to reconcile the evolution of oceanic 87Sr/86Sr with early crustal growth models. Continents are enriched in phosphorus, which is essential to the biosphere. The emergence of the continents would thus have triggered an increase in the production of oxygen by photosynthetic micro-organisms, possibly contributing to the oxidation of the atmosphere 2.4 Ga ago

Ultrasonic characterisation of wheel hub/axle interference fit pressures

Railway wheels are secured onto the axle by means of an interference fit. The wheel is press fitted onto a pre-lubricated axle, and the resulting interference fit induces a contact pressure at the interface. Occasionally railway wheels fail by fatigue, with the initiation point for the failure frequently traced to the interference fit. The aim of this work is to use ultrasonic reflection to non-destructively determine contact conditions in the interference fit. The rough surface contact at the interference fit interface behaves like a spring. If the contact pressure is high the interface is conformal with few air gaps, the stiffness is then high and the transmission of an ultrasonic wave is permitted. However, when pressure is low more air gaps exist, interfacial stiffness is then reduced and more of the ultrasound is reflected. Normalised contact pressure was determined from this stiffness. Maps of the interface have been produced which show the contact pressure to peak at the edges of the fit, and to experience a continuous variation about a mean value elsewhere

Higgs couplings beyond the Standard Model

We consider the Higgs boson decay processes and its production, and provide a parameterisation tailored for testing models of new physics beyond the Standard Model. We also compare our formalism to other existing parameterisations based on scaling factors in front of the couplings and to effective Lagrangian approaches. Different formalisms allow to best address different aspects of the Higgs boson physics. The choice of a particular parameterisation depends on a non-obvious balance of quantity and quality of the available experimental data, envisaged purpose for the parameterisation and degree of model independence, importance of the radiative corrections, scale at which new particles appear explicitly in the physical spectrum. At present only simple parameterisations with a limited number of fit parameters can be performed, but this situation will improve with the forthcoming experimental LHC data. Detailed fits can only be performed by the experimental collaborations at present, as the full information on the different decay modes is not completely available in the public domain. It is therefore important that different approaches are considered and that the most detailed information is made available to allow testing the different aspects of the Higgs boson physics and the possible hints beyond the Standard Model.Comment: 22 pages, 5 figures, 5 tables. This version is an update including the most recent Higgs data and new fits to two extra model

Higgs couplings: disentangling New Physics with off-shell measurements

After the discovery of a scalar resonance, resembling the Higgs boson, its couplings have been extensively studied via the measurement of various production and decay channels on the invariant mass peak. Recently, it has been suggested the possibility to use off-shell measurements: in particular, CMS has published results based on the high- invariant mass cross section of the process $gg \to ZZ$, which contains the contribution of the Higgs. While this measurement has been interpreted as a constraint on the Higgs width after very specific assumptions are taken on the Higgs couplings, in this letter we show that a much more model-independent interpretation is possible.Comment: 6pp, 1 figur

A Kinematic And Electromyographic Study Of The Mechanisms Contributing To Cerebellar Intention Tremor And Dysmetria

The kinematic and electromyographic (EMG) characteristics of cerebellar tremor and dysmetria were investigated in six Cebus monkeys. Cerebellar dysfunction was produced by reversible cooling lesions of the dentate and interposed nuclei. The aims of the study were (1) to compare the characteristics of the cerebellar intention tremor that occurs after the end of a voluntary movement (static or terminal tremor) with the tremor that occurs after the limb has been perturbed, (2) to determine the role played by stretch-evoked activity in generating this tremor, (3) to investigate the nature of the tremor that occurs during a voluntary movement (kinetic tremor) and (4) to describe the characteristics of dysmetric movements.;It was found that the static intention tremor after an elbow movement had the same characteristics as the tremor that occurs after a perturbation of the same limb. The frequency of the tremor in both situations was affected in a similar way by different mechanical loads and neither was dependent on visual feedback of limb position. Stretch-evoked proprioceptive activity was essential to produce the classic 3-4Hz cerebellar intention tremor.;The kinetic tremor was associated with an early burst of EMG activity in the antagonist muscle. This burst was no longer accurately programmed and appeared to be produced from stretch of the antagonist muscle. This antagonist burst was followed by a second burst of activity in the agonist muscle. This burst had the properties of a motor-servo as it was independent of vision, of short latency (50-80 ms) from the time of the deflection in trajectory produced by the early antagonist and its size was directly proportional to the size of the deflection.;Dysmetric (hypermetric) movements made during cerebellar cooling were asymmetric; that is, they had accelerations of long duration and small magnitude and decelerations of short duration and large magnitude. Control movements of all amplitudes, on the other hand, are nearly symmetric. Thus dysmetric movements were not simply inappropriately triggered normal movements. Hypermetric movements were associated with prolonged and less phasic bursts of agonist activity and a delayed burst of antagonist activity.;It is concluded that cerebellar disorders result from inappropriate stretch-evoked activity and from disordered descending central commands