On the metastability of the Standard Model vacuum

If the Higgs mass m_H is as low as suggested by present experimental information, the Standard Model ground state might not be absolutely stable. We present a detailed analysis of the lower bounds on m_H imposed by the requirement that the electroweak vacuum be sufficiently long-lived. We perform a complete one-loop calculation of the tunnelling probability at zero temperature, and we improve it by means of two-loop renormalization-group equations. We find that, for m_H=115 GeV, the Higgs potential develops an instability below the Planck scale for m_t>(166\pm 2) GeV, but the electroweak vacuum is sufficiently long-lived for m_t < (175\pm 2) \GeV.Comment: LaTex 23 pages, 4 eps figures. Misprint in the abstract corrected, reference adde

The smallest neutrino mass

We consider models where one Majorana neutrino is massless at tree level (like the see saw with two right-handed neutrinos), and compute the contribution to its mass m generated by two-loop quantum corrections. The result is m \sim 10^{-13}eV in the SM and m \sim 10^{-10} eV (tanBeta/10)^4 in the MSSM, compatible with the restricted range suggested by Affleck-Dine baryogenesis.Comment: 6 pages. v2: final version to appear on PLB; important reference adde

Softened Gravity and the Extension of the Standard Model up to Infinite Energy

Attempts to solve naturalness by having the weak scale as the only breaking of classical scale invariance have to deal with two severe difficulties: gravity and the absence of Landau poles. We show that solutions to the first problem require premature modifications of gravity at scales no larger than $10^{11}$ GeV, while the second problem calls for many new particles at the weak scale. To build models that fulfil these properties, we classify 4-dimensional Quantum Field Theories that satisfy Total Asymptotic Freedom (TAF): the theory holds up to infinite energy, where all coupling constants flow to zero. We develop a technique to identify such theories and determine their low-energy predictions. Since the Standard Model turns out to be asymptotically free only under the unphysical conditions $g_1 = 0$, $M_t = 186$ GeV, $M_\tau = 0$, $M_h = 163$ GeV, we explore some of its weak-scale extensions that satisfy the requirements for TAF.Comment: 60 pages. Final version to appear on JHEP. v3: references adde

The light stop window

We show that a right-handed stop in the 200-400 GeV mass range, together with a nearly degenerate neutralino and, possibly, a gluino below 1.5 TeV, follows from reasonable assumptions, is consistent with present data, and offers interesting discovery prospects at the LHC. Triggering on an extra jet produced in association with stops allows the experimental search for stops even when their mass difference with neutralinos is very small and the decay products are too soft for direct observation. Using a razor analysis, we are able to set stop bounds that are stronger than those published by ATLAS and CMS.Comment: 21 pages, 9 figures. v2: fig. 9b has been updated and revised at large values of the stop/neutralino mass splitting. The discussion of stop co-annihilations has been upgraded including Sommerfeld enhancement

“Il lato oscuro della valutazione”: La percezione della valutazione e dell’assessment in un contesto universitario

The aim of this contribution is to focus on the reasons for the rejection of evaluation practices in the field of higher education and to understand how this refusal is connected to the “mechanism of unveiling of the educational system” that the evaluation implements. It attempts to provide an interpretative framework regarding the perception of students (but also university professors) of evaluation practices adopted in the university context, proposing to give an explanation that, although provisional, can contribute to the understanding of the refusal that usually accompanies the evaluation, which becomes not only the spy of a malaise but also that of a malfunctioning of teaching.This perception is an intervening factor, often neglected, but important if we want to fully understand the “how, when and why” the learning and the meaning of teaching are realized,and if we want to reveal the reasoning behind the educational action system with which it is possible to clarify the logics that guide the management of the interventions by the teachers.L’obiettivo di questo contributo è quello di mettere a fuoco le ragioni legate al rifiuto delle pratiche valutative nel campo dell’istruzione superiore e di capire come tale rifiuto sia connesso al “meccanismo di svelamento del sistema didattico” che la valutazione mette in atto.Esso tenta di fornire un quadro interpretativo riguardante la percezione degli studenti (ma anche dei docenti universitari) delle pratiche di valutazione adottate in contesto universitario,proponendosi di dare una spiegazione che, seppur provvisoria, possa offrire un contributo alla comprensione del rifiuto che generalmente accompagna la valutazione, il quale diventa non solo la spia di un malessere ma anche quella di un cattivo funzionamento dell’insegnamento. Tale percezione è un fattore interveniente, spesso trascurato, ma importante se si vuolecomprendere appieno “il come, il quando e il perché” si realizzi l’apprendimento e il senso dell’insegnamento, nonché se si desideri svelare ragionamenti che stanno alla base del sistema d’azione didattico con i quali è possibile chiarire le logiche che guidano la gestione degli interventi da parte dei docenti

Dendritic Cell Differentiation

Dauer et al. ([1][1]) presented a method to differentiate CD14+ cells into mature dendritic cells (DC) within 48 h (FastDC). FastDC displayed a DC-like morphology, down-regulated CD14, and induced proliferation of autologous T cells against soluble Ags as efficiently as standard monocyte-derived D

Laparoscopic Left Adrenalectomy with Submesocolic and Retropancreatic Approach

Introduction: The safety and efficacy of laparoscopic transperitoneal lateral adrenalectomy and retroperitoneoscopic adrenalectomy have been reported. The aim is to report the authors’ experience in laparoscopic left adrenalectomy with an alternative transperitoneal submesocolic and retropancreatic approach with patient supine

Caring for AML Patients During the COVID-19 Crisis: An American and Italian Experience.

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the subsequent pandemic have impacted every aspect of oncology care worldwide. Healthcare systems have been forced to rapidly change practices in order to maximize the safety of patients and healthcare providers and preserve scare resources. Patients with acute myeloid leukemia are at increased risk of complications from SARS-CoV-2 not only due to immune compromise related to the malignancy but also due to the acuity of the disease and intensity of treatment. These issues have created unique challenges during this difficult time. In this article, we present the approaches taken by two groups of hematologist/oncologists, one in the United States and one in Italy, who have been caring for acute myeloid leukemia (AML) patients in the face of the pandemic

Higgs mass implications on the stability of the electroweak vacuum

We update instability and metastability bounds of the Standard Model electroweak vacuum in view of the recent ATLAS and CMS Higgs results. For a Higgs mass in the range 124--126 GeV, and for the current central values of the top mass and strong coupling constant, the Higgs potential develops an instability around $10^{11}$ GeV, with a lifetime much longer than the age of the Universe. However, taking into account theoretical and experimental errors, stability up to the Planck scale cannot be excluded. Stability at finite temperature implies an upper bound on the reheat temperature after inflation, which depends critically on the precise values of the Higgs and top masses. A Higgs mass in the range 124--126 GeV is compatible with very high values of the reheating temperature, without conflict with mechanisms of baryogenesis such as leptogenesis. We derive an upper bound on the mass of heavy right-handed neutrinos by requiring that their Yukawa couplings do not destabilize the Higgs potential.Comment: 14 pages, 8 figure