Discovery potential of the Standard Model Higgs in CMS at the LHC

This thesis presents the discovery potential of the Standard Model Higgs boson in the CMS experiment at the LHC. Detailed studies have been carried out to evaluate the detector performance in the difficult $\rm H\to\gamma\gamma$ channel. The electromagnetic crystal calorimeter is of main importance in this channel and it has been designed according stringent performance requirements. Test beam data of lead tungstate crystals have been analysed and it is shown that the performance of the crystals can meet the requirements. The Higgs decay into two photons has been studied with full detector simulation and the Higgs mass has been reconstructed. A potential danger for the photon measurement are the photon conversions in the detector material in front of the electromagnetic calorimeter. Different methods to recover these converted photons are developed and it is shown that, including the recovered conversions does not degrade the Higgs mass resolution. To complete the full Standard Model Higgs discovery range, studies of the other decay channels are reviewed and updated taking into account the next to leading order corrections to the cross-sections. A new study for the $\rm H\to ZZ\to2$l2$\nu$ channel shows that it can give an important contribution above m\sb{\rm H} = 400 GeV. An estimate of the integrated luminosity needed for an observable Higgs signal is derived. It is shown that a fast discovery (integrated luminosity less than 10 fb\sp{-1}) can be expected if the Higgs mass is in the range of 130-550 GeV. The most difficult regions are the low mass range (m\sb{\rm H}600 GeV). With 100 fb\sp{-1} of integrated luminosity the full mass range can be covered

How to guarantee the natural origin of nutraceutical and pharmaceutical products? The potential of the stable isotope ratios analysis

The analysis of the ratio between the heavy and light isotopes of the elements carbon (13C/12C), nitrogen (15N/14N), sulfur (34S/32S), oxygen (18O/16O) and hydrogen (2H/1H) is well known for its power to discriminate the geographical origin and guarantee the authenticity of many agri-food products [1]. In recent years, the field of application of this technique has expanded to include nutraceuticals and pharmaceuticals, in particular in order to guarantee their natural origin. Chemically identical molecules are significantly different from an isotopic point of view due to the isotopic fractionation that occurs in different processes and reactions (biological, biochemical, physical, chemical, etc.) which generates unique isotopic signatures in the product synthesized by plants compared to that produced in the laboratory usually starting from fossil sources. Thanks to the coupling of isotopic mass spectrometry to liquid chromatography (LC-IRMS) and gas chromatography (GC-IRMS) it is now possible to discriminate between natural and/or synthetic origin not only of the bulk product but also of its specific components. The "Compound specific analysis" makes it possible to identify much more sophisticated frauds than in the past such as, for example, the addition of a single synthetic component to a natural substrate in order to artificially increase its strength. In this context, the δ13C analysis is a suitable tool to discriminate between Monacolin K (contained in red yeast rice-based dietary supplements) and the marketed statin [2] and between natural L-theanine (extracted from Camellia Sinensis) and the biosynthetically produced one [3]. The isotope ratios of hydrogen and, in some cases, carbon exhibit significantly different ranges of variability between natural extracts (such as curcuminoids [4] and cannabidiols [5]) and their synthetic adulterant, allowing for the identification of not only the two origins, but also the fraudulent additions of synthetic products to the natural complex (spiked samples). The combination of GC-MS/MS and GC-IRMS is potentially useful for botanical classification between lavender (Lavandula angostifolia) and lavandin (Lavandula hybrida) essential oils thus representing an additional powerful tool for assessing the authenticity of commercial essential oil

High density balsamic vinegar: application of stable isotope ratio analysis to determine watering down

Aceto balsamico di Modena IGP (ABM) is an Italian worldwide appreciated PGI (Protected Geographical Indication) vinegar, obtained from cooked and/or concentrated grape must (at least 20% of the volume), with the addition of at least 10% of wine vinegar and a maximum 2% of caramel for color stability (EU Reg. 583/ 2009). The geographical origin of ABM ingredients is never specified. Since 2013, the European Committee for Standardization (CEN) has issued a method for determining the water fraudulently added to the vinegar and the balsamic vinegar product (EN16466-3 18O-IRMS). The method is based on the stable isotope ratios analysis of the bulk AMB sample (expressed as δ18O in ‰ with respect to the international standard V-SMOW2). Balsamic vinegars with very high density (higher than 1.37 g / mL of sugar) are available on the market. They are obtained by adding a high amount of concentrated must or by a long aging of the product in the barrel, which leads to an intense evaporation and concentration. Products with such high density cannot be analyzed by using the official method as reported in the EN16466-3 18O-IRMS. Indeed, in this conditions, the equilibration between CO2 and the water in the sample, being the base principle of the process, does not occur. In this work, the official method has been modified and validated, calculating repeatability (r) and reproducibility (R), by proceeding with a prior dilution of the sample and by applying a correction to the data in order to eliminate the diluent isotopic contribution. Considering the limit value of δ18O for a non-watered product reported in the literature for vinegar and for rectified concentrated must [1-2], the threshold limit of δ18O below which the ABM product can be considered as adulterated was identified. References [1] J. Agric. Food Chem. 2014, 62, 32, 8197–8203 [2] Food Control 2013, 29(1), 107–11

Statistical Studies of the Robustness of the LHC Main Dipole Mechanical Structure

This paper describes two methods used to study the effect of the tolerances of the components on the structure of the LHC main dipole. The first method, called semi-statistical, is useful for the study of the effect of single different parameters and allows the determination of the acceptable variance of the dimensions of magnet components. The second one, fully statistical, allows the study of the combined effect of many parameters. The use of these two methods allowed to evaluate with good confidence the robustness of two different dipole cross-section designs, featuring austenitic and aluminium alloy collars, respectively

FEM Computations Concerning the Effect of Friction in Two LHC Main Dipole Structures

The mechanical behaviour of a dipole structure is considered when also friction is taken into account, studying its effect on different components and in different conditions. In particular the difference in behavior between a structure with aluminium collars and one with austenitic steel ones was studied

Coherent states for FLRW space-times in loop quantum gravity

We construct a class of coherent spin-network states that capture proprieties of curved space-times of the Friedmann-Lama\^itre-Robertson-Walker type on which they are peaked. The data coded by a coherent state are associated to a cellular decomposition of a spatial ($t=$const.) section with dual graph given by the complete five-vertex graph, though the construction can be easily generalized to other graphs. The labels of coherent states are complex SL(2, \mathbbm{C}) variables, one for each link of the graph and are computed through a smearing process starting from a continuum extrinsic and intrinsic geometry of the canonical surface. The construction covers both Euclidean and Lorentzian signatures; in the Euclidean case and in the limit of flat space we reproduce the simplicial 4-simplex semiclassical states used in Spin Foams.Comment: 10 pages, 1 figure, published versio

Compatibility of radial, Lorenz and harmonic gauges

We observe that the radial gauge can be consistently imposed \emph{together} with the Lorenz gauge in Maxwell theory, and with the harmonic traceless gauge in linearized general relativity. This simple observation has relevance for some recent developments in quantum gravity where the radial gauge is implicitly utilized.Comment: 9 pages, minor changes in the bibliograph

Authentication and geographical characterisation of Italian grape musts through glucose and fructose carbon isotopic ratios determined by LC IRM

The authenticity of grape musts is normally checked through the stable isotopic analysis of carbon (δ13C) after fermentation and distillation by following the official OIV MA AS-312-06 method. Unfortunately, it presents some issues that are difficult to over come. Grape must samples can only be analysed after they have been fermented to obtain ethanol. The process must be carried out under careful control of the fermentation to avoid the presence of unwanted by-products arising from a premature fermentation interruption. Moreover, if the musts have been preserved by the addition of sulphur dioxide (SO2 ), they must undergo an additional step to eliminate the SO2 , which would affect the fermentation. Once the product has been fermented, the ethanol must be separated using specific distillation columns (such as the Cadiot ones) making it possible to obtain ethanol free of isotopic fractionation with a minimum alcohol degree of 95% vol. In this study, the alternative use of a technique based on δ13C isotopic analysis of the major sugars of the grape must by liquid chromatography coupled with isotope ratio mass spectrometry (LC-IRMS) is provided. In LC–IRMS, analytes are separated on an LC system and consecutively oxidized in an online reactor to CO2 , which is required for the determination of compound-specific carbon isotopic ratios. This technique has been already used in the study of matrices such as wine [1], ethanol [1,2], glycerol [2], and honey [3] to detect fraudulent alterations of their natural composition such as the addition of exogenous sugars to the products. The LC-IRMS allows a single separation of the individual components of a sample and makes it possible to determine their δ13C values online, avoiding both the disadvantages of off-line methods and the disadvantages of methods requiring a derivatization step (such as GC-C-IRMS), causing the addition of extra carbons. In order to discriminate between musts from different areas of Italy, a preliminary dataset was considered; the δ13C isotopic ratios of glucose and fructose of around 100 authentic Italian must samples from 16 different sampling regions were analysed. In addition, the δ13C variability in authentic and fake must (added with increasing percentages of exogenous sugars) has been explored and tested to verify their validity as fraud detectors. The two analysed parameters, ranging from −29.8‰ to −21.9‰, are well correlated (R2 = 0.7802) and the northern Italian regions showed significantly more negative δ13C values for both sugars than the rest of the dataset (Figure 1). By using the LC-IRMS technique, the addition of exogenous sugars, such as fructose and glucose from C4 photosynthetic cycle plants, is easily detectable as it modifies the δ13C of the individual sugar

Instantaneous conduction and switching losses in two-level voltage source inverters

A mathematical model is derived which allows to compute instantaneously the conduction and switching losses in two-level voltage source inverters (2L-VSIs) regardless of the employed modulation scheme. The model is based on the use of switching vectors applied to the considered VSI, taking into account the instantaneous conduction and switching losses of the semiconductor devices. The advantages of this method are, (i) it can be extended to any type of VSI and any modulation scheme, (ii) it can be applied to analyze the power losses of VSIs during any desired period, and (iii) it can be easily implemented in any kind of the simulation software (e.g. Matlab/Simulink)