Phenomenology of TMDs

We present a review of current Transverse Momentum Dependent (TMD) phenomenology focusing our attention on the unpolarized TMD parton distribution function and the Sivers function. The paper introduces and comments about the new Collins-Soper-Sterman (CSS) TMD evolution formalism. We make use of a selection of results obtained by several groups to illustrate the achievements and the failures of the simple Gaussian approach and the TMD CSS evolution formalism.Comment: 10 pages, 5 figures, to appear in the proceedings of the TRANSVERSITY 2014, Chia, Italy, 9-13 June, 201

The Boer-Mulders effect in unpolarized SIDIS: an analysis of the COMPASS and HERMES data on the cos⁡2ϕ\cos 2 \phi asymmetry

We present a phenomenological analysis of the $\cos 2 \phi$ asymmetry recently measured by the COMPASS and HERMES collaborations in unpolarized semi-inclusive deep inelastic scattering. In the kinematical regimes explored by these experiments the asymmetry arises from transverse-spin and intrinsic transverse-momentum effects. We consider the leading-twist contribution, related to the so-called Boer-Mulders transverse-polarization distribution $h_1^{\perp}(x, k_T^2)$, and the twist-4 Cahn contribution, involving unpolarized transverse-momentum distribution functions. We show that a reasonably good fit of the data is achieved with a Boer-Mulders function consistent with the main theoretical expectations. Our conclusion is that the COMPASS and HERMES measurements represent the first experimental evidence of the Boer-Mulders effect in SIDIS.Comment: 11 pages, 7 figures, published version in PR

Azimuthal asymmetries in unpolarized Drell-Yan processes and the Boer-Mulders distributions of antiquarks

Using a previous extraction of the quark Boer-Mulders distributions from semiinclusive deep inelastic scattering data, we fit the unpolarized Drell-Yan data on the $\cos 2 \phi$ asymmetry, determining the antiquark Boer-Mulders distributions. A good agreement with the data is found in the region of low $q_T$, where the transverse-momentum factorization approach applies.Comment: 7 pages, 3 figure

Non-perturbative QCD effects in qTq_T spectra of Drell-Yan and ZZ-boson production

The factorization theorems for transverse momentum distributions of dilepton/boson production, recently formulated by Collins and Echevarria-Idilbi-Scimemi in terms of well-defined transverse momentum dependent distributions (TMDs), allows for a systematic and quantitative analysis of non-perturbative QCD effects of the cross sections involving these quantities. In this paper we perform a global fit using all current available data for Drell-Yan and $Z$-boson production at hadron colliders within this framework. The perturbative calculable pieces of our estimates are included using a complete resummation at next-to-next-to-leading-logarithmic accuracy. Performing the matching of transverse momentum distributions onto the standard collinear parton distribution functions and recalling that the corresponding matching coefficient can be partially exponentiated, we find that this exponentiated part is spin-independent and resummable. We argue that the inclusion of higher order perturbative pieces is necessary when data from lower energy scales are analyzed. We consider non-perturbative corrections both to the intrinsic nucleon structure and to the evolution kernel and find that the non-perturbative part of the TMDs could be parametrized in terms of a minimal set of parameters (namely 2-3). When all corrections are included the global fit so performed gives a $\chi^2/{\rm d.o.f.} \lesssim 1$ and a very precise prediction for vector boson production at the Large Hadron Collider (LHC).Comment: 24 pages, 11 figures. v2: new subsection added, discussion on the stability of the calculations and on higher order contributions improved, results unchange

Atlas and Informative System of the Lagoon of Venice: updated tools for a higher management efficiency in Natura 2000 sites

La laguna di Venezia è un ecosistema complesso per comprendere il quale è necessario integrare dati ed informazioni provenienti da discipline diverse raccolti da differenti Enti ed Istituti di ricerca. L’Osservatorio Naturalistico della Laguna, del Comune di Venezia, nasce fondamentalmente per raccogliere queste informazioni ed organizzarle affinché possano essere fruibili sia dai vari Servizi e Direzioni dell’Amministrazione Comunale, sia dalle istituzioni scientifiche e dai cittadini. Per questo motivo è stato prodotto l’Atlante della Laguna, una raccolta di 103 mappe tematiche, ciascuna delle quali è corredata da una scheda esplicativa, suddivise in 5 sezioni: Geosfera, Biosfera, Antroposfera, Ambiti di Tutela e Analisi Integrate. L’Atlante rappresenta solo un primo passo verso la diffusione e la validazione dei dati ambientali. Attualmente si sta realizzando un Sistema Informativo della Laguna (SIL) che metterà a disposizione di vari utenti le informazioni, le elaborazioni ed i materiali raccolti dall’Osservatorio durante le sue attività (in parte già sintetizzati nell’Atlante). Il passo successivo sarà la raccolta e la diffusione delle informazioni e dei dati che altri soggetti proprietari vorranno inserire nel SIL, attraverso appositi protocolli di scambio. I vantaggi di un Sistema Informativo rispetto ad un volume cartaceo sono molteplici e noti, e vanno dall’aggiornabilità del dato alla possibilità di elaborarlo secondo necessità contingenti. L’utilizzo di questi strumenti per la gestione delle aree umide è esemplificato attraverso un caso studio: la Valutazione di Incidenza dell’area utilizzata per il tiro al piattello localizzata a Campalto (Venezia), attività dismessa ormai da diversi anni.The lagoon of Venice is a complex ecosystem that can be understood only by the integration of data and information with a multidisciplinary approach. The ‘Osservatorio Naturalistico della Laguna’ of Venice Municipality has been created with the aim of gathering and organizing all kinds of information, so that it can be used by administrators, scientific institutions and citizens. For this reason, the Lagoon Atlas was produced. The Atlas is composed by 103 tematic maps, each accompanied by an explicatory schedule, subdivided into 5 sections: Geosphere, Biosphere, Anthroposphere, Protection and Integrated Analysis. The Atlas represents a first step towards the distribution and validation of environmental data. An Informative System of the Lagoon (SIL) is currently under construction, and this will allow to obtain all kind of information, elaboration and materials gathered by the Osservatorio during its activities (already partially summarized in the Atlas). The next step will be to gather and distribute information and data that other subjects will include in the SIL, through specific protocols of exchange. The advantages of using an Informative System rather than paper materials are obvious, spanning from the possibility to update data to the possibility of elaborating them according to the needs. The use of these tools for wetland management is exemplified by a case study: the assessment of projects in the area of Campalto (Venice), that in the past was used for shooting

Phenomenology of TMDs Using SCET

We present a global fit of current available data for Drell-Yan and Z-boson production using the Transverse Momentum Dependent evolution formalism of Refs. [1–4]. We performed our analysis including perturbative calculable contributions up to next-to-next-to-leading-logarithmic accuracy. We took into account non-perturbative corrections both to the intrinsic nucleon structure and to the evolution kernel

TMDs: Evolution, modeling, precision

The factorization theorem for $q_T$ spectra in Drell-Yan processes, boson production and semi-inclusive deep inelastic scattering allows for the determination of the non-perturbative parts of transverse momentum dependent parton distribution functions. Here we discuss the fit of Drell-Yan and $Z$-production data using the transverse momentum dependent formalism and the resummation of the evolution kernel. We find a good theoretical stability of the results and a final $\chi^2/{\rm points}\lesssim 1$. We show how the fixing of the non-perturbative pieces of the evolution can be used to make predictions at present and future colliders.Comment: 6 pages, 3 pdf figures, uses webofc.cls. Invited talk delivered by I. Scimemi at the Fourth International Workshop on "Transverse Polarisation Phenomena in Hard Processes" (Transversity 2014), Chia, Cagliari, Italy, June 9-13, 2014. To appear in EPJ Web of Conference