In this talk I will discuss some theoretical subtleties of the top-quark mass determination, issue which persists in being highly controversial. In the first part of the talk I will compare several NLO generators for top-pair production implemented in the POWHEG BOX framework, that differ by the level of accuracy employed to describe the top decay. The impact of the shower Monte Carlo programs, used to complet the NLO events generated by POWHEG BOX, is also studied. In particular, I discuss the two most widely used shower Monte Carlo programs, i.e. Pythia 8.2 and Herwig 7.1, and how it is possible to interface them with processes that contain decayed emitting resonances. The second part is instead devoted to the study of linear renormalons in observables that can be employed to determine the top mass.

Scopri di più »# Tag Archives: Evento scientifico

## Hadron Electromagnetic Form Factors

Electromagnetic form factors give Lorentz invariant information about the electromagnetic charge distributions inside hadrons. They are thus a key probe of the dynamics of QCD in the low energy, non-perturbative regime. Importantly, it is well known that due to its characteristically light mass, the pion plays an important role in low energy observables. In particular, the effects of implementing pion loop corrections at the hadron level (as opposed to the quark level) will be discussed. I will show results for electromagnetic form factors calculated in the NJL Model, and in particular, that one obtains am improved prediction of the predicted Hyperon Magnetic moment when the pion loop effects are implemented in this way. One important input into this calculation is the pion form factor itself. Modern extractions of the pion form factor for moderate values of the photon virtuality (above about 0.3 GeV^2) arise from a model dependent extraction from pion electro-production data. In the second half of the talk, a simple model of pion electro-production, will be described and used to examine the model dependence of the extraction method. In the context of this simple model, the extracted form factor is systematically overestimated.

Scopri di più »## New Probes of Ultra-Low-Mass Dark Matter and Dark Sectors

I present a brief overview of some novel detection strategies for ultra-low-mass bosonic dark matter that forms a coherently oscillating classical field. Possible effects of such dark matter fields include time-varying spin-precession effects and time-varying fundamental constants. These effects can be sought with various low-energy atomic and astrophysical probes, including magnetic resonance techniques, spectroscopy measurements, microwave/optical cavities (maser/laser interferometers), fifth-force experiments, and Big Bang nucleosynthesis. Further possible effects of dark bosons include the mediation of anomalous new forces that can be sought with electric dipole moment experiments, parity non-conservation experiments and (antimatter) spectroscopy measurements. Existing and new experimental and observational data have allowed us and other groups to improve on previous observational bounds on dark matter and dark boson interactions by many orders of magnitude.

Scopri di più »## Fractal aspects of Yang-Mills fields

Yang-Mills fields present scale invariance, what allows the theory to be renormalized. In this talk we show that fractal structures can be formed by fields described by this theory. Such fractal structure allow for recursive equations that enable the calculation of high order perturbative calculations. In addition, it leads to power-law distributions of energy and momentum, and therefore explains the emergence of the non extensive Tsallis statistics in high energy physics and in hadron physics. Similarities with the concept of thermofractal, recently introduded, are discussed, as well as comparison with experiments.

Scopri di più »## Progetto SICURA (SICUrezza RAdiologica)

SICURA: il progetto LNF che ha vinto il bando della Regione Lazio per Progetti di Gruppi di ricerca Verrà presentato il progetto SICURA (SICUrezza RAdiologica), una proposta innovativa elaborata da Catalina Curceanu e da Roberto Bedogni che ha vinto il bando della Regione Lazio per Progetti di Gruppi di ricerca – Conoscenza e Cooperazione per un Nuovo Modello di Sviluppo. Gli elementi chiave del progetto, che si inserisce negli ambiti della sicurezza radiologica e lotta al terrorismo, sono l’impiego di sensori a basso costo e la loro integrazione mirata a rivelare simultaneamente radiazioni X, gamma e neutroni, per la realizzazione di una sonda portatile per operare nell’ambito dei controlli di sicurezza e di ordine pubblico. Grazie all’elevata capacità di interconnessione, con la sonda SICURA si potranno monitorare, in tempo reale, scenari come piazze, scuole, eventi sportivi, concerti o centri commerciali.. Il seminario illustrerà il layout preliminare del sistema di misura SICURA, le sue peculiarità rispetto a sistemi commercialmente disponibili, ed i requisiti a cui dovrà rispondere.

Scopri di più »## Electron Ion Collider

An overview on the current design status of the electron-ion collider project eRHIC, proposed at BNL, is presented.

Scopri di più »## 2019 Winter institute on Axions in Astrophysics and Cosmology

Aim of the meeting: This informal meeting is intended for extensive discussions on astrophysical and cosmological implications of Axions. A certain number of more formal seminars will be open to the general audience: Seminars: Monday 21/01 2:30pm Enrico Nardi (INFN-LNF) “Astrophobic Axions” Monday 21/01 3:00pm Fred Bjorkeroth (INFN-LNF) “Peccei-Quinn Symmetry as a Flavor Symmetry” Tuesday 22/01 2.30pm: Luca Visinelli (Uppsala University) “Future Challenges for Axion Physics” Wednesday 23/01 2:30pm: Maurizio Giannotti (Barry University) “Bounds and Hints on Axions from Stars” Thursday 24/01, 2:30pm Meeting: “The KLASH scientific case” (For the KLASH Conceptual Design report)

Scopri di più »## Very high field magnets for next hadron colliders: new technologies and opportunities

To decisively upgrade the luminosity of the LHC, and increase its Physics reach, the High Luminosity LHC project is opening a new territory, developing a broad range of new technologies: accelerator magnets in the 12 tesla range based on advanced Nb3Sn technology, long superconducting links rated for 100 kA with novel MgB2 superconductors, new type of SRF cavities, etc…. The talk will discuss the status of these new technologies for HL-LHC and especially the high field magnets, now at the verge of entering into production, as well as the studies under way for the post-LHC Hadron Collider. In particular, for the FCC stronger Nb3Sn magnets, for 16 T, are under design and the first R&D on HTS (High Temperature Superconductors) accelerator magnets has started. HTS magnet results are promising to open the 20 T range, which would bring the 100 km FCC even beyond the 100 TeV threshold.

Scopri di più »## PADME general meeting

## Low-energy strangeness studies at DAFNE and J-PARC

The aim of the "Low-energy strangeness studies ad DAFNE and J-PARC" workshop is to give an outline of the major issues in the low energy strangeness nuclear physics sector and to discuss still open problems to be addressed in the near future. The low energy strangeness QCD represents one of the most interesting sectors in physics,the existence of broad hyperon resonances just below the Kbar-N threshold, like the debated Lambda* state, makes the Kbar-N interaction a complicated non-perturbative and multi-channel problem which puzzled theoreticians and experimentalists for decades. The accurate investigation of the Kbar-N and Hyperons-N interaction above, below and at the threshold deeply impacts many sectors of physics ranging from nuclear physics to astrophysics. The workshop is organized in the framework of the StrangeMatter Italy-Japan project supported by the Ministero degli Affari Esteri e della Collaborazione Internazionale (MAECI) and is sponsored by the Istituto Nazionale di Fisica Nucleare and by the CENTRO FERMI – Museo Storico della Fisica e Centro Studi e Ricerche Enrico Fermi. Local Organizing Committee: Catalina Curceanu Raffaele Del Grande Kristian Piscicchia Alessandro Scordo Diana Laura Sirghi Magdalena Skurzok Alessandra Tamborrino Orsini

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