Marco Guzzi

The University of Manchester, School of Physics and Astronomy, Post-Doc

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Papers by Marco Guzzi

New parton distribution functions from a global analysis of quantum chromodynamics

Physical Review D, 2016

Deeply Virtual Neutrino Scattering at Leading Twist

We illustrate the generalization of results concerning exclusive electromagnetic processes in the... more We illustrate the generalization of results concerning exclusive electromagnetic processes in the deeply virtual limit (DVCS) to the case of the weak interactions.We briefly describe the derivation of the differential cross section for neutrino-nucleon reactions mediated by the neutral current and the amplitude for similar reactions mediated by the charged currents.

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QCD Studies at Hadron Colliders and in Deeply Virtual Neutrino Scattering

This thesis work summarizes studies in QCD for applications both at hadron colliders and in exclu... more This thesis work summarizes studies in QCD for applications both at hadron colliders and in exclusive processes. In the first part we focus our attention on the study of the initial state scaling violations and the evolution of the unpolarized parton distributions through Next-to-Next to Leading Order (NNLO) in $\alpha_s$, the strong coupling, suitable for precision studies of the parton model at the LHC. Specifically, we analize the methods available to solve the equations and develope the theory of the logarithmic expansions at the same perturbative order. A study of the Higgs total cross section is included. The theoretical analysis is accompanied by the developement of professional software partly documented in this thesis. We also include one study of the evolution of the transverse spin distributions (the Soffer inequality) and a parallel study of the asymmetries for the Drell-Yan process for the proposed Pax experiment at GSI at NLO. In the second part we introduce the extens...

format_quoteStatistical values reveal crucial fluctuations in measured variables, highlighting the need for a deeper analysis of underlying factors.format_quote

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Developments in the parton distribution functions of the proton

EPJ Web of Conferences, 2014

A general overview on the parton distribution functions of the proton extracted by QCD global ana... more A general overview on the parton distribution functions of the proton extracted by QCD global analyses of experimental data is presented. In particular, their impact on physics observables of interest for the LHC and general results of QCD analyses at the next-to-next-to-leading order approximation are discussed. a

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Deeply Virtual Neutrino Scattering at Leading Twist

Nuclear Physics B - Proceedings Supplements, 2007

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Deeply Virtual Neutrino Scattering (DVNS)

Journal of High Energy Physics, 2005

format_quoteExamines the implications of varying parameters on the overall model outcomes.format_quote

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Leading twist amplitudes for exclusive neutrino interactions in the deeply virtual limit

Physical Review D, 2005

format_quoteUtilizes novel combinations of decay channels to enhance precision in measurements of particle interactions.format_quote

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Axions from intersecting branes and decoupled chiral fermions at the Large Hadron Collider

Nuclear Physics B, 2010

We present a study of a class of effective actions which show typical axion-like interactions, an... more We present a study of a class of effective actions which show typical axion-like interactions, and of their possible effects at the Large Hadron Collider. One important feature of these models is the presence of one pseudoscalar which is a generalization of the Peccei-Quinn axion. This can be very light and very weakly coupled, with a mass which is unrelated to its couplings to the gauge fields, described by Wess Zumino interactions. We discuss two independent realizations of these models, one derived from the theory of intersecting branes and the second one obtained by decoupling one chiral fermion per generation (one right-handed neutrino) from an anomaly-free mother theory. The key features of this second realization are illustrated using a simple example. Charge assignments of intersecting branes can be easily reproduced by the chiral decoupling approach, which remains more general at the level of the solution of its anomaly equations. Using considerations based on its lifetime, we show that in brane models the axion can be dark matter only if its mass is ultralight (∼ 10 −4 eV), while in the case of fermion decoupling it can reach the GeV region, due to the absence of fermion couplings between the heavy Higgs and the light fermion spectrum. For a GeV axion derived from brane models we present a detailed discussion of its production rates at the LHC.

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Room temperature photoluminescence of Ge multiple quantum wells with Ge-rich barriers

Applied Physics Letters, 2011

We report on the observation of room temperature direct band gap photoluminescence in compressive... more We report on the observation of room temperature direct band gap photoluminescence in compressively strained-Ge multiple quantum wells with Ge-rich SiGe barriers. A detailed experimental study of the temperature dependence of the photoluminescence is carried out from 5 K up to room temperature. We find that the direct gap photoluminescence at room temperature is due to the thermal excitation of carriers from L-type to Gamma-type confined states. Room temperature photoluminescence shows that Ge/SiGe multiple quantum wells are promising candidates for efficient light emitting devices monolithically integrated on Si.

Precision studies of the NNLO DGLAP evolution at the LHC with Candia

by Marco Guzzi and Alessandro Cafarella

Computer Physics Communications, 2008

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Relic densities of dark matter in the U(1)-extended NMSSM and the gauged axion supermultiplet

by Claudio Coriano and Marco Guzzi

Physical Review D, 2012

We compute the dark matter relic densities of neutralinos and axions in a supersymmetric model wi... more We compute the dark matter relic densities of neutralinos and axions in a supersymmetric model with a gauged anomalous U (1) symmetry, kinetically mixed with U (1) Y of hypercharge. The model is a variant of the USSM (the U (1) extended NMSSM), containing an extra U (1) symmetry and an extra singlet in the superpotential respect to the MSSM, where gauge invariance is restored by Peccei-Quinn interactions using a Stückelberg multiplet. This approach introduces an axion (Im b) and a saxion (Re b) in the spectrum and generates an axino component for the neutralino. The Stückelberg axion (Im b) develops a physical component (the gauged axion) after electroweak symmetry breaking. We classify all the interactions of the Lagrangian and perform a complete simulation study of the spectrum, determining the neutralino relic densities using micrOMEGAs. We discuss the phenomenological implications of the model analyzing mass values for the axion from the milli-eV to the MeV region. The possible scenarios that we analyze are significantly constrained by a combination of WMAP data, the exclusion limits from direct axion searches and the veto on late entropy release at the time of nucleosynthesis.

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