115 research outputs found
Panizzi, Antonio, scheda biografica per il Senato della Repubblica Italiana
No full textLa scheda riassume i dati biografici del senatore Antonio Panizzi, nell'ambito del progetto di digitalizzazione degli Archivi del Senato della Repubblica italiana
Tagging of Biomedical Articles on CiteULike: A Comparison of User, Author and Professional Indexing
No full textThis paper examines the context of online indexing from the viewpoint of three different groups: users, authors, and professional indexers. User tags, author keywords and descriptors were collected from academic journal articles, which were both indexed in Pubmed and tagged on CiteULike, and analysed. Descriptive statistics, informetric measures, and thesaural term comparison shows that there are important differences in the use of keywords between the three groups in addition to similarities which can be used to enhance support for search and browse. While tags and author keywords were found that matched descriptors exactly, other terms which did not match but provided important expansion to the indexing lexicon were found. These additional terms could be used to enhance support for searching and browsing in article databases as well as to provide invaluable data for entry vocabulary and emergent terminology for regular updates to indexing systems. Additionally, the study suggests that tags support organisation by association to task, projects and subject while making important connections to traditional systems which classify into subject categories
Effective theory of a doubly charged singlet scalar: complementarity of neutrino physics and the LHC
No full textWe consider a rather minimal extension of the Standard Model involving just one extra particle, namely a single singlet scalar and its antiparticle . We propose a model independent effective operator, which yields an effective coupling of to pairs of same sign weak gauge bosons, . We also allow tree-level couplings of to pairs of same sign right-handed charged leptons of the same or different flavour. We calculate explicitly the resulting two-loop diagrams in the effective theory responsible for neutrino mass and mixing. We propose sets of benchmark points for various masses and couplings which can yield successful neutrino masses and mixing, consistent with limits on charged lepton flavour violation (LFV) and neutrinoless double beta decay. We discuss the prospects for discovery at the LHC, for these benchmark points, including single and pair production and decay into same sign leptons plus jets and missing energy. The model represents a minimal example of the complementarity between neutrino physics (including LFV) and the LHC, involving just one new particle, the
Large width effects in processes of production of extra quarks decaying to Dark Matter at the LHC
No full textThis paper explores the effects of finite width in processes of pair production of a heavy eXtra Quark (XQ) with charge 2/3 and its subsequent decay into a Dark Matter (DM) candidate – either scalar or vector – and Standard Model (SM) up-type quarks at the Large Hadron Collider (LHC). This dynamics has been ignored so far in standard experimental searches of heavy quarks decaying to DM and we assess herein the regions of validity of current approaches, based on the assumption that the XQ has a narrow width. Further, we discuss the configurations of masses, widths and couplings where the latter breaks down.This paper explores the effects of finite width in processes of pair production of a heavy eXtra Quark (XQ) with charge 2/3 and its subsequent decay into a Dark Matter (DM) candidate -- either scalar or vector -- and Standard Model (SM) up-type quarks at the Large Hadron Collider (LHC). This dynamics has been ignored so far in standard experimental searches of heavy quarks decaying to DM and we assess herein the regions of validity of current approaches, based on the assumption that the XQ has a narrow width. Further, we discuss the configurations of masses, widths and couplings where the latter breaks down
Public relations, Panizzi-style
No full textIN a collection of letters by and to Sir Anthony Panizzi, chiefly relating to the history of the British Museum, assembled and recently presented by the author to the British Library (Add. MSS. 70839-70854), are two letters written by Sir Anthony to the Irish essayist and politician John Wilson Croker in 1852 that are revealing of the way publicity about the British Museum Library was handled in the mid-nineteenth century. They also reveal Panizzi's attitude towards the problems he faced and his relationship to a prominent political figure of the day
Spectral gap solutions of the Kirchhoff equation
No full textThe author proves that for initial data in a set S subset of suitable Sobolev spaces, the solutions of the Cauchy-Dirichlet problem for the dissipative Kirchhoff are global in time and decay exponentially. The functions in S do not satisfy any additional regularity assumption, instead they must satisfy a condition relating their energy with the largest lacuna in their Fourier expansion. The larger is the lacuna the larger is the energy allowed
Deconstructing resonant Higgs pair production at the LHC: effects of coloured and neutral scalars in the NMSSM test case
No full textWe study resonant production of pairs of Standard Model (SM)-like Higgs bosons, in the presence of new neutral Higgs states together with new coloured scalars (stops or sbottoms) in loops within the Next-to-Minimal Supersymmetric SM (NMSSM). This is used as a test case to prove that the Large Hadron Collider has sensitivity to a variety of effects stemming from interferences between resonant (heavy) Higgs diagrams and/or among these and non-resonant topologies involving loops of both tops and stops. These effects can alter significantly the naive description of individual s-channel Breit-Wigner resonances, leading to distortions of the latter which, on the one hand, maymask their presence but, on the other hand, could enable one to extract features of the underlying new physics scenario. This last aspect is made possible through a decomposition of the gg → hh signal process into all its amplitude components, each of which has a well-defined coupling structure. Ultimately, such effects can be traced back to the relevant Feynman diagrams and can enable a detailed interpretation of this process. To illustrate this, we introduce various Benchmark Points that exhibit potentially observable features during the current and/or upcoming runs of the LHC in one or more of the three customary di-Higgs decay channels: b¯bb¯b, b¯bτ +τ− and b¯bγγ
The 750 GeV threshold to a new particle world
No full textWe show how an excess in the diphoton channel can be the effect of neither a resonance nor an end-point in a cascade decay, but rather of a threshold for virtual production of a pair of extra quarks, each with half of peak invariant mass, onsetting in both the -initiated production and the -induced decay of an off-shell boson. For our analysis we consider as paradigmatic example the 750 GeV excess previously seen at the end of 2015 with the Run 2 data of the LHC but not confirmed with 2016 data
Deconstructing squark contributions to di-Higgs production at the LHC
No full textWe present a novel approach to the study of di-Higgs production via gluon-gluon fusion at the LHC. The relevant Feynman diagrams involving two Standard Model-like Higgs bosons are computed within a simplified model approach that enables one to interpret possible signals of new physics in a model-independent way as well as to map these onto specific theories. This is possible thanks to a decomposition of such a signal process into all its squared amplitudes and their relative interferences, each of which has a well-defined coupling structure. We illustrate the power of this procedure for the case of both a minimal and next-to-minimal representation of Supersymmetry, for which the new physics effects are due to top squarks entering the loops of . The squarks yield both a change of the integrated cross section and peculiar kinematic features in its differential distributions with respect to the Standard Model. These effects can in turn be traced back to the relevant diagrammatic and coupling structures and allow for a detailed analysis of the process. In order to do so, we perform systematic scans of the parameter spaces of such new physics scenarios and identify benchmark points which exhibit potentially observable features during the current and upcoming runs of the LHC
Extra quarks decaying to dark matter beyond the narrow width approximation
No full textWe explore the effects induced by a finite width in processes of pair production of a heavy top-quark partner and its subsequent decay into a bosonic Dark Matter (DM) candidate -- either scalar or vector -- and a SM up-type quark at the Large Hadron Collider (LHC). We discuss the configurations of masses, widths and couplings where this phenomenology can be important in a simple model with just one such objects. Finally, we emphasise the correct definition of signal and background to be adopted as well as stress the importance of new dedicated experimental searches
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