Maurizio Frigeni - Academia.edu (original) (raw)
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Papers by Maurizio Frigeni
Archimede, 2014
"A geometric proof of Kepler's First Law" Kepler's First Law is proven along the same lines foll... more "A geometric proof of Kepler's First Law"
Kepler's First Law is proven along the same lines followed by Newton in his "Principia". As a first step one considers a body moving along a conic curve under the action of a centripetal force directed towards a focus: it is proven that the force is inversely proportional to the square of the distance of the body from the focus. Then one proves that, given the initial position and velocity of the body, and a fixed center of force, it is always possible to construct a conic curve representing the trajectory of the body. The proofs make use of a geometrical construction for the radius of curvature of conics, already appeared on Archimede.
Physics Letters B, 1992
With some of the superpartners in a favourable (and small) range of masses and couplings, easily ... more With some of the superpartners in a favourable (and small) range of masses and couplings, easily explorable at LEP II, the precision measurements at LEP I could already give a signal interpretable as indirect evidence for supersymmetry, even without knowing the top quark mass. A Z-wave-function renormalization effect due to virtual gaugino-higgsinos might systematically lower all the Z-widths without affecting the asymmetries. This would best show up in a low value of the parameter E3 (as defined by AltareUi and Barbieri), which we compute, together with El and E2, in the minimal supersymmetric standard model with all one loop effects included. As a byproduct, we give explicit expressions for the ~-parameters in terms of one loop unrenormalized Green functions, applicable to any SU (2) × U (1) gauge theory with an arbitrary number of Higgs doublets.
Physics Letters B, 1991
In a general softly broken supcrsymmetric theory with Higgs doublets only, we calculate the radia... more In a general softly broken supcrsymmetric theory with Higgs doublets only, we calculate the radiative corrections to the mass of the lightcst neutral ttiggs boson in the particular case where all the extra particles introduced by supersymmetry are close in mass and all heavier than the Fermi scale. In this situation the corrections are large and trivially calculable. We also consider the limiting case in which all the superpartners become arbitrarily heavy. The connection of these considerations with the Higgs of the standard model is elucidated.
Physics Letters B, 1991
Radiative corrections modify in a significant way the tree level mass of the hghtest supersymmetn... more Radiative corrections modify in a significant way the tree level mass of the hghtest supersymmetnc Hlggs panicle in models with Hlggs doublets only Using a simple approximate description of these corrections, their impact on the supersymmetnc Hlggs searches at LEP Is illustrated
Nuclear Physics B, 1990
In the minimal supersymmetric standard model we analyse the radiative corrections to M~. the p-pa... more In the minimal supersymmetric standard model we analyse the radiative corrections to M~. the p-parameter and the lepton asymmetries at the Z°pole. We show how the radiative corrections of the standard model with a light Higgs give a lower bound on the corrections in the supersymmetric model. This feature, once the top quark mass is known, may serve to distinguish between the two different theories.
Nuclear Physics B, 1989
In a general supergravity theory, with minimal particle content, we describe the area of the para... more In a general supergravity theory, with minimal particle content, we describe the area of the parameter space that gives rise to a massive, stable neutralino X, with a cosmologically significant relic density. In this region of parameters we show the effect of the lightest Higgs exchange on the elastic neutralino-nucleus cross section, relevant to the direct detection methods. Finally, we visualize how the same parameter space can be probed expcrimcntally by studying chargino and neutralino pair production at e*e collidcrs.
Nuclear Physics B, 1991
We study multi-lepton final states arising from the decay of charginos and neutralinos produced i... more We study multi-lepton final states arising from the decay of charginos and neutralinos produced in hadronic collisions at current and future center-of-mass energies. We compare the signals predicted by Minimal Supersymmetry with the main Standard Model backgrounds, namely vector boson and heavy quark production. * The exchange of virtual scalar quarks in the t-channel would only increase the production rate. Alternative indirect sources of charginos and neutralinos, such as the weak decays of strongly produced scalar quarks and gluinos, do have large rates and have been studied previously 13). In these cases however jets are always present in the final states, while in this study we chose to concentrate on purely leptonic final states, as will shortly be explained. * The case of one single charged lepton will be studied in subsect. 2.2. ** We here neglect the possibility of the W having a large p 1, due to QCD radiation, because we are requiring that the charged lepton momentum be balanced by missing energy and not by a jet. Including the effects of the p~distribution of the W would only make the signal-to-noise ratio worse. * We calculated the contribution from processes with more leptons in the final state, some of which escape detection, and found it negligible. * Here we only considered direct production of W-pairs, having neglected the (possibly dominant) process in which a massive ti pair is produced and each t decays into a real W and a b-quark.
Archimede, 2014
"A geometric proof of Kepler's First Law" Kepler's First Law is proven along the same lines foll... more "A geometric proof of Kepler's First Law"
Kepler's First Law is proven along the same lines followed by Newton in his "Principia". As a first step one considers a body moving along a conic curve under the action of a centripetal force directed towards a focus: it is proven that the force is inversely proportional to the square of the distance of the body from the focus. Then one proves that, given the initial position and velocity of the body, and a fixed center of force, it is always possible to construct a conic curve representing the trajectory of the body. The proofs make use of a geometrical construction for the radius of curvature of conics, already appeared on Archimede.
Physics Letters B, 1992
With some of the superpartners in a favourable (and small) range of masses and couplings, easily ... more With some of the superpartners in a favourable (and small) range of masses and couplings, easily explorable at LEP II, the precision measurements at LEP I could already give a signal interpretable as indirect evidence for supersymmetry, even without knowing the top quark mass. A Z-wave-function renormalization effect due to virtual gaugino-higgsinos might systematically lower all the Z-widths without affecting the asymmetries. This would best show up in a low value of the parameter E3 (as defined by AltareUi and Barbieri), which we compute, together with El and E2, in the minimal supersymmetric standard model with all one loop effects included. As a byproduct, we give explicit expressions for the ~-parameters in terms of one loop unrenormalized Green functions, applicable to any SU (2) × U (1) gauge theory with an arbitrary number of Higgs doublets.
Physics Letters B, 1991
In a general softly broken supcrsymmetric theory with Higgs doublets only, we calculate the radia... more In a general softly broken supcrsymmetric theory with Higgs doublets only, we calculate the radiative corrections to the mass of the lightcst neutral ttiggs boson in the particular case where all the extra particles introduced by supersymmetry are close in mass and all heavier than the Fermi scale. In this situation the corrections are large and trivially calculable. We also consider the limiting case in which all the superpartners become arbitrarily heavy. The connection of these considerations with the Higgs of the standard model is elucidated.
Physics Letters B, 1991
Radiative corrections modify in a significant way the tree level mass of the hghtest supersymmetn... more Radiative corrections modify in a significant way the tree level mass of the hghtest supersymmetnc Hlggs panicle in models with Hlggs doublets only Using a simple approximate description of these corrections, their impact on the supersymmetnc Hlggs searches at LEP Is illustrated
Nuclear Physics B, 1990
In the minimal supersymmetric standard model we analyse the radiative corrections to M~. the p-pa... more In the minimal supersymmetric standard model we analyse the radiative corrections to M~. the p-parameter and the lepton asymmetries at the Z°pole. We show how the radiative corrections of the standard model with a light Higgs give a lower bound on the corrections in the supersymmetric model. This feature, once the top quark mass is known, may serve to distinguish between the two different theories.
Nuclear Physics B, 1989
In a general supergravity theory, with minimal particle content, we describe the area of the para... more In a general supergravity theory, with minimal particle content, we describe the area of the parameter space that gives rise to a massive, stable neutralino X, with a cosmologically significant relic density. In this region of parameters we show the effect of the lightest Higgs exchange on the elastic neutralino-nucleus cross section, relevant to the direct detection methods. Finally, we visualize how the same parameter space can be probed expcrimcntally by studying chargino and neutralino pair production at e*e collidcrs.
Nuclear Physics B, 1991
We study multi-lepton final states arising from the decay of charginos and neutralinos produced i... more We study multi-lepton final states arising from the decay of charginos and neutralinos produced in hadronic collisions at current and future center-of-mass energies. We compare the signals predicted by Minimal Supersymmetry with the main Standard Model backgrounds, namely vector boson and heavy quark production. * The exchange of virtual scalar quarks in the t-channel would only increase the production rate. Alternative indirect sources of charginos and neutralinos, such as the weak decays of strongly produced scalar quarks and gluinos, do have large rates and have been studied previously 13). In these cases however jets are always present in the final states, while in this study we chose to concentrate on purely leptonic final states, as will shortly be explained. * The case of one single charged lepton will be studied in subsect. 2.2. ** We here neglect the possibility of the W having a large p 1, due to QCD radiation, because we are requiring that the charged lepton momentum be balanced by missing energy and not by a jet. Including the effects of the p~distribution of the W would only make the signal-to-noise ratio worse. * We calculated the contribution from processes with more leptons in the final state, some of which escape detection, and found it negligible. * Here we only considered direct production of W-pairs, having neglected the (possibly dominant) process in which a massive ti pair is produced and each t decays into a real W and a b-quark.