522 research outputs found
Erratum: Identification of the goat CSN1S1F allele by means of PCR-RFLP method (Animal Genetics (2000) 31 (342))
No full textErratum
Ramunno L., Cosenza G., Pappalardo M., Pastore N., Gallo D., Di Gregorio P. & Masina P. (2000) Identi®cation of
the goat CSN1S1F allele by means of PCR-RFLP method. Animal Genetics 31, 34
Higgs boson and Top quark masses as tests of Electroweak Vacuum Stability
No full textThe measurements of the Higgs boson and top quark masses can be used to extrapolate the Standard Model Higgs potential at energies up to the Planck scale. Adopting a Next-to-Next- to-Leading Order renormalization procedure, we argue that electroweak vacuum stability is at present allowed, discuss the associated theoretical and experimental errors and the prospects for its future tests.The measurements of the Higgs boson and top quark masses can be used to extrapolate the Standard Model Higgs potential at energies up to the Planck scale. Adopting a Next-to-Next-to-Leading Order renormalization procedure, we argue that electroweak vacuum stability is at present allowed, discuss the associated theoretical and experimental errors and the prospects for its future tests. © Copyright owned by the author(s)
On the Veltman Condition, the Hierarchy Problem and High-Scale Supersymmetry
No full textIn this paper, we have considered the possibility that the Standard Model, and its minimal extension with the addition of singlets, merges with a high-scale supersymmetric theory at a scale satisfying the Veltman condition and therefore with no sensitivity to the cutoff. The matching of the Standard Model is achieved at Planckian scales. In its complex singlet extension, the matching scale depends on the strength of the coupling between the singlet and Higgs fields. For order 1 values of the coupling, still in the perturbative region, the matching scale can be located in the TeV ballpark. Even in the absence of quadratic divergences, there remains a finite adjustment of the parameters in the high-energy theory, which should guarantee that the Higgs and the singlets in the low-energy theory are kept light. This fine-tuning (unrelated to quadratic divergences) is the entire responsibility of the ultraviolet theory and remains as the missing ingredient to provide a full solution to the hierarchy problem
Electroweak metastability and Higgs inflation
No full textExtrapolating the Standard Model Higgs potential at high energies, we study the barrier between the electroweak and Planck scale minima. The barrier arises by taking the central values of the relevant experimental inputs, that is the strong coupling constant and the top quark and Higgs masses. We then extend the Standard Model by including a non-minimal coupling to gravity, and explore the phenomenology of the Higgs inflation model. We point out that even configurations that would be metastable in the Standard Model, become viable for inflation if the non-minimal coupling is large enough to flatten the Higgs potential at field values below the barrier; we find that the required value of the non-minimal coupling is smaller than the one needed for the conventional Higgs inflation scenario (which relies on a stable Standard Model Higgs potential, without any barrier); in addition, values of the top mass which are larger than those required in the conventional scenario are allowed
Up quark masses from down quark masses
No full textThe quark and charged lepton masses and the angles and phase of the CKM mixing matrix are nicely reproduced in a model which assumes SU(3)xSU(3) flavour symmetry broken by the v.e.v.'s of fields in its bi-fundamental representation. The relations among the quark mass eigenvalues, m_u/m_c \approx m_c/m_t \approx m^2_d/m^2_s \approx m^2_s/m^2_b \approx \Lambda^2_{GUT}/M^2_{Pl}, follow from the broken flavour symmetry. Large tan(beta) is required which also provides the best fits to data for the obtained textures. Lepton-quark grandunification with a field that breaks both SU(5) and the flavour group correctly extends the predictions to the charged lepton masses. The seesaw extension of the model to the neutrino sector predicts a Majorana mass matrix quadratically hierarchical as compared to the neutrino Dirac mass matrix, naturally yielding large mixings and low mass hierarchy for neutrinos
The Higgs mass range from Standard Model false vacuum Inflation in scalar-tensor gravity
No full textIf the standard model is valid up to very high energies it is known that the Higgs potential can develop a local minimum at field values around 10 15 - 10 17 GeV , for a narrow band of values of the top quark and Higgs masses. We show that in a scalar-tensor theory of gravity such Higgs false vacuum can give rise to viable inflation if the potential barrier is very shallow, allowing for tunneling and relaxation into the electroweak scale true vacuum. The amplitude of cosmological density perturbations from inflation is directly linked to the value of the Higgs potential at the false minimum. Requiring the top quark mass, the amplitude and spectral index of density perturbations to be compatible with observations, selects a narrow range of values for the Higgs mass, m H = 126.0 ± 3.5 GeV , where the error is mostly due to the theoretical uncertainty of the 2-loop renormalization group equation. This prediction could be soon tested at the Large Hadron Collider. Our inflationary scenario could also be further checked by better constraining the spectral index and the tensor-to-scalar ratio
The halting effect of baroclinicity in vortex merging
No full textStudies the quasigeostrophic merging dynamics of axisymmetric baroclinic vortices to understand how baroclinicity affects merging rates and the development of the nonlinear cascade of enstrophy. The initial vortices are taken to simulate closely the horizontal and vertical structure of Gulf Stream rings. A quasigeostrophic model is set with a horizontal resolution of 9 km and 6 vertical levels to resolve the mean stratification of the Gulf Stream region. The results show that the baroclinic merging is slower than the purely barotropic process. -from Author
Aumentare l’effetto della paura: stimolo pubblicitario e livello di astrazione del comportamento
No full text
Analisi dei livelli marini estremi e delle acque alte lungo il litorale ravennate
No full textIn tutto l’Alto Adriatico i fenomeni di acqua alta espongono i territori costieri ad un elevato livello di rischio
per inondazione marina. Obiettivo del presente studio è la stima dei livelli marini estremi e dei relativi periodi
di ritorno per le aree costiere vulnerabili della Provincia di Ravenna, punto di partenza di grande rilevanza per
la Protezione Civile nella messa a punto di adeguati sistemi di previsione e di allerta.
Le osservazioni disponibili si riferiscono alle registrazioni con cadenza di 10 minuti del mareografo di Porto
Corsini (Ravenna), stazione della Rete Mareografica Nazionale, e coprono un periodo di dieci anni, dal 2000
al 2009. Il controllo di qualità e l’alta correlazione con i valori orari relativi allo stesso periodo archiviati dall’Istituzione
Centro Previsioni e Segnalazioni Maree del Comune di Venezia per la stazione di Punta della Salute
assicurano la validità dei dati utilizzati nell’analisi.
La stima dei valori estremi è stata effettuata considerando la probabilità limite congiunta degli r eventi annuali
più elevati sia della serie temporale dei livelli osservati che di quella dei residui, ottenuta rimuovendo la
marea astronomica tramite analisi armonica effettuata con il programma t_tide. La selezione è stata realizzata
considerando indipendenti valori estremi separati da almeno 78 ore, in modo da includere in un unico evento
le oscillazioni di livello dovute alle sesse che possono accompagnare i fenomeni di surge, e cercando riscontro
nelle serie temporali dei dati meteorologici ed ondametrici registrati dalle stazioni più vicine.
Il probability plot test indica un buon adattamento del modello ai dati esaminati per in corrispondenza del
quale si ottengono livelli di 0.85, 1.05 e 1.28 m e residui di 0.61, 0.79 e 1.02 m per tempi di ritorno rispettivamente
di 2, 10 e 100 anni
- …
