arXiv subjects
Publications and source records attributed to Gennaro Corcella.
I discuss the theoretical interpretation of the top-quark mass, which is extracted in standard and alternative measurements at the LHC. In particular, I point out that the top mass extracted in analyses relying on the use of Monte Carlo event generators must be close to the pole mass and review recent work aiming at estimating the theoretical uncertainty.
Searching for Z' bosons, predicted in GUT-inspired U(1)' gauge models and in the Sequential Standard Model, is one of the main challenges of the experiments carried out at the Large Hadron Collider. Such searches have so far focused on high-mass dilepton pairs, assuming that the Z' has only Standard Model decay modes, and have set mass exclusion limits around 2.5-3 TeV. In this talk, I investigate supersymmetric Z' decays at 14 TeV LHC, extending the MSSM in such a way to accommodate extra heavy gauge bosons. In particular, I study Z' decays into pairs of sleptons, charginos and neutralinos, leading to final states with leptons and missing energy, and present results for few reference points of the parameter space, consistent with a SM-like Higgs boson with a mass around 125 GeV. I also discuss the feasibility to search for Dark Matter candidates, by analysing Z' decays into the lightest MSSM neutralinos.
I study the phenomenology of heavy neutral bosons Z', predicted in GUT-inspired U(1)' models, at the Large Hadron Collider. In particular, I investigate possible signatures due to Z' decays into superymmetric particles, such as chargino, neutralino and sneutrino pairs, leading to final states with charged leptons and missing energy. The analysis is carried out at sqrt{s}=14 TeV, for a few representative points of the parameter space of the Minimal Supersymmetric Standard Model, suitably modified to accommodate the extra Z' boson and consistent with the discovery of a Higgs-like boson with mass around 125 GeV. Results are presented for several observables and compared with those obtained for direct Z' decays into lepton pairs, as well as direct production of supersymmetric particles. For the sake of comparison, Z' phenomenology in an effective supersymmetric extension of the Sequential Standard Model is also discussed.
I discuss a few issues related to the systematic error on the top mass measurement at hadron colliders, due to hadronization effects. Special care is taken about the impact of bottom-quark fragmentation in top decays, especially on the reconstruction relying on final states with leptons and J/psi in the dilepton channel. I also debate the relation between the measured mass and its theoretical definition, and report on work in progress, based on the Monte Carlo simulation of fictitious top-flavoured hadrons, which may shed light on this issue and on the hadronization systematics.
I investigate production and decay of heavy neutral gauge bosons Z' in GUT-inspired U(1)' groups and in the Sequential Standard Model. In particular, decays into supersymmetric particles, such as slepton, chargino and neutralino pairs, as predicted in the MSSM, are accounted for, with a special interest in final states with leptons and missing energy. For a representative point of the parameter space, it is found that the inclusion of supersymmetric decay modes has an impact of 200-300 GeV on the Z' mass exclusion limits.
Searching for heavy neutral gauge bosons Z', predicted in extensions of the Standard Model based on a U(1)' gauge symmetry, is one of the challenging objectives of the experiments carried out at the Large Hadron Collider. In this paper, we study Z' phenomenology at hadron colliders according to several U(1)'-based models and in the Sequential Standard Model. In particular, possible Z' decays into supersymmetric particles are included, in addition to the Standard Model modes so far investigated. We point out the impact of the U(1)' group on the MSSM spectrum and, for a better understanding, we consider a few benchmarks points in the parameter space. We account for the D-term contribution, due to the breaking of U(1)', to slepton and squark masses and investigate its effect on Z' decays into sfermions. Results on branching ratios and cross sections are presented, as a function of the MSSM and U(1)' parameters, which are varied within suitable ranges. We pay special attention to final states with leptons and missing energy and make predictions on the number of events with sparticle production in Z' decays, for a few values of integrated luminosity and centre-of-mass energy of the LHC.
I study the phenomenology of new heavy neutral gauge bosons Z', predicted by GUT-driven U(1)' gauge groups and by the Sequential Standard Model. BSM decays into supersymmetric final states are accounted for, besides the SM modes so far investigated. I give an estimate of the number of supersymmetric events in Z' decays possibly expected at the LHC, as well as of the product of the Z' cross section times the branching fraction into electron and muon pairs.
We provide ingredients and recipes for computing signals of TeV-scale Dark Matter annihilations and decays in the Galaxy and beyond. For each DM channel, we present the energy spectra of electrons and positrons, antiprotons, antideuterons, gamma rays, neutrinos and antineutrinos e, mu, tau at production, computed by high-statistics simulations. We estimate the Monte Carlo uncertainty by comparing the results yielded by the Pythia and Herwig event generators. We then provide the propagation functions for charged particles in the Galaxy, for several DM distribution profiles and sets of propagation parameters. Propagation of electrons and positrons is performed with an improved semi-analytic method that takes into account position-dependent energy losses in the Milky Way. Using such propagation functions, we compute the energy spectra of electrons and positrons, antiprotons and antideuterons at the location of the Earth. We then present the gamma ray fluxes, both from prompt emission and from Inverse Compton scattering in the galactic halo. Finally, we provide the spectra of extragalactic gamma rays. All results are available in numerical form and ready to be consumed.
I study the production of heavy neutral gauge bosons Z' at the LHC in U(1)' models, inspired by Grand Unification Theories, as well as in the Sequential Standard Model, accounting for possible decays into supersymmetric channels. I shall consider the MSSM and present results on branching ratios and event rates with sparticle production at the LHC, taking particular care about final states with charged leptons and missing energy.
I discuss the recent implementation of medium-modified splitting functions within the HERWIG angular-ordered parton shower algorithm and present a few results on transverse momentum, energy and angular distributions.
I discuss a few selected topics related to the reconstruction of the mass of the top quark at hadron colliders. In particular, the relation between the measured top mass and theoretical definitions, such as the pole or MSbar mass, is debated. I will also summarize recent studies on the Monte Carlo uncertainty due to the fragmentation of bottom quarks in top decays.
The recent theory developments and latest experimental results on heavy-flavour production in Deep Inelastic Scattering and at hadron colliders are summarized. Models of heavy quarkonia production, non-perturbative corrections to fragmentation, theory of heavy-hadron production in heavy-ion collisions, and interpretation of new exotic hadrons are discussed. Progress in event generators development is reported. Most recent experimental results from HERA and e+e- colliders as well as from proton-(anti)proton and heavy ion experiments are presented and the role of charm and beauty quarks in the analyses of the proton structure is stressed.
Top-quark physics is one of the main fields of investigation at the Tevatron accelerator and, ultimately, at the LHC. We perform a phenomenological analysis of ttbar events at hadron colliders, with a focus on observables relying on bottom-quark fragmentation in top-quark decay. In particular, we investigate the B-lepton invariant-mass distribution in the dilepton channel and give an estimate of the contribution of bottom fragmentation to the Monte Carlo uncertainty on the top-quark mass reconstruction.
An unspecified strong dynamics may give rise to composite vectors sufficiently light that their interactions, among themselves or with the electroweak gauge bosons, be approximately described by an effective Lagrangian invariant under $SU(2)_L\times SU(2)_R/ SU(2)_{L+R}$. We study the production at the LHC of two such states by vector boson fusion or by the Drell--Yan process in this general framework and we compare it with the case of gauge vectors from a $SU(2)_L\times SU(2)_R\times SU(2)^N$ gauge model spontaneously broken to the diagonal SU(2) subgroup by a generic $σ$-model. Special attention is payed to the asymptotic behaviour of the different amplitudes in both cases. The expected rates of multi-lepton events from the decay of the composite vectors are also given. A thorough phenomenological analysis and the evaluation of the backgrounds to such signals, aiming at assessing the visibility of composite-vector pairs at the LHC, is instead deferred to future work.
Modified Altarelli-Parisi splitting functions were recenty proposed to model multi-parton radiation in a dense medium and describe jet quenching, one of most striking features of heavy-ion collisions. We implement medium-modified splitting functions in the HERWIG parton shower algorithm, which satisfies the angular ordering prescription, and present a few parton-level results, such as transverse momentum, angle and energy-fraction distributions, which exhibit remarkable medium-induced effects. We also comment on the comparison with respect to the results yielded by other implementations of medium-modified splitting functions in the framework of virtuality-ordered parton cascades.
In this summary we present the current status of the Standard Model of strong and electroweak interactions from the theoretical and experimental point of view. Some discussion is also devoted to the exploration of possible New Physics signals beyond the Standard Model.
This paper describes the top quark physics measurements that can be performed with the first LHC data in the ATLAS and CMS experiments.
We review the main features of Monte Carlo generators for top quark phenomenology and present some results for t-tbar and single-top signals and backgrounds at the LHC.