Top mass determination, Higgs inflation, and vacuum stability

The possibility that new physics beyond the Standard Model (SM) appears only at the Planck scale $M_P$ is often considered. However, it is usually argued that new physics interactions at $M_P$ do not affect the SM stability phase diagram, so the latter is obtained neglecting these terms. According to this diagram, for the current experimental values of the top and Higgs masses, our universe lives in a metastable state (with very long lifetime), near the edge of stability. Contrary to these expectations, however, we show that the stability phase diagram strongly depends on new physics and that, despite claims to the contrary, a more precise determination of the top (as well as of the Higgs) mass will not allow to discriminate between stability, metastability or criticality of the electroweak vacuum. At the same time, we show that the conditions needed for the realization of Higgs inflation scenarios (all obtained neglecting new physics) are too sensitive to the presence of new interactions at $M_P$. Therefore, Higgs inflation scenarios require very severe fine tunings that cast serious doubts on these models.Comment: 20 pages, 10 figure

Impact of Gravity on Vacuum Stability

In a pioneering paper on the role of gravity on false vacuum decay, Coleman and De Luccia showed that a strong gravitational field can stabilize the false vacuum, suppressing the formation of true vacuum bubbles. This result is obtained for the case when the energy density difference between the two vacua is small, the so called thin wall regime, but is considered of more general validity. Here we show that when this condition does not hold, however, {\it a strong gravitational field (Planckian physics) does not necessarily induce a total suppression of true vacuum bubble nucleation}. Contrary to common expectations then, gravitational physics at the Planck scale {\it does not stabilize the false vacuum}. These results are of crucial importance for the stability analysis of the electroweak vacuum and for searches of new physics beyond the Standard Model.Comment: 6 pages, 4 figure

Lifetime of the electroweak vacuum and sensitivity to Planck scale physics

If the Standard Model (SM) is valid up to extremely high energy scales, then the Higgs potential becomes unstable at approximately 10(11) GeV. However, calculations of the lifetime of the SM vacuum have shown that it vastly exceeds the age of the Universe. It was pointed out by two of us (V.B., E.M.) that these calculations are extremely sensitive to effects from Planck scale higher-dimensional operators and, without knowledge of these operators, firm conclusions about the lifetime of the SM vacuum cannot be drawn. The previous paper used analytical approximations to the potential and, except for Higgs contributions, ignored loop corrections to the bounce action. In this work, we do not rely on any analytical approximations and consider all contributions to the bounce action, confirming the earlier result. It is surprising that the Planck scale operators can have such a large effect when the instability is at 10(11) GeV. There are two reasons for the size of this effect. In typical tunneling calculations, the value of the field at the center of the critical bubble is much larger than the point of the instability; in the SM case, this turns out to be numerically within an order of magnitude of the Planck scale. In addition, tunneling is an inherently nonperturbative phenomenon and may not be as strongly suppressed by inverse powers of the Planck scale. We include effective Phi(6) and Phi(8) Planck-scale operators and show that they can have an enormous effect on the tunneling rate

A novel global postural alteration? Qualitative assessment of hallux valgus and swallowing disorder in human posture: A preliminary investigation on the incidence during age span for promoting psycho-physical and postural well-being

Hallux Valgus (HV) and Swallowing Disorder (SD) are two multifactorial postural and biomechanical alterations. It is very important to look for the incidence of these two conditions in order to promote psycho-physical and postural well-being. Our study aimed to clinically assess the presence of HV and SD in a large group with different ages spans. Fours skilled professionals performed the assessment following clinical criteria. A total of 61 volunteers subjects (163.5 ± 14.1 cm; 59.7 ± 15.7 kg; 22.9 ± 13.2 yrs.) were selected for the study. The 51% of the sample showed the HV alteration, 30% and 73% respectively for male and female. Regarding ages cluster, the HV was present in 44% under 20 yrs., in 53% between 21 and 40 yrs., in 75% over 40 yrs. The 46% of the sample showed a SD condition, 50% and 42% respectively for male and female. As for ages cluster, the incidence of SD was in 50% of subjects under 20 yrs., in 41% between 21 and 40 yrs., in 50% over 40 yrs. The 39% of subjects with HV showed a SD condition. On the other hand, the 43% of subjects with SD showed the HV deformity. HV and SD are postural disorders and most often occur together. In this framework, HV and SD should be interpreted as sign of global postural alteration and for this reason it is fundamental to assess them. Further research is needed on these two parameters in order to find out the optimal relationship between HV and SD

Can tongue position and cervical ROM affect postural oscillations? A pilot and preliminary study

The tongue is considered an important part of the postural system, so it is fundamental to understand how it can interfere with the humans’ postural oscillations. The aim of this preliminary investigation is to understand the effects of different tongue position and cervical ROM on postural oscillations measured in a stabilometric test. Thirteen voluntary subjects were recruited (30.8 ± 9.7 yrs.; 173.6 ± 14.9 cm; 72.6 ± 15.6 kg) and tested in three different random tongue conditions: comfortable tongue position (CT), palatal spot position (ST) and low tongue position (LT). All tests were performed with open eyes. Stabilometric test were performed with a pressure platform. In addition, the cervical ROM was assessed in the CT condition to create a baseline measurement and to find out baseline relationship with cervical ROM and postural oscillations. Data analysis indicates no significant difference in CoP sway path length for CT / ST / LT (260.7 ± 106.5 mm / 236.9 ± 79.3 mm / 272.9 ± 89.3 mm, respectively). A moderate but significant correlation is present between postural oscillations and cervical rotation ROM (R = -0.59; p = .03), indicating that good postural oscillations are connected with a free ROM of the highest part of the body. The results of this preliminary investigation do not support the use of different tongue position during postural assessment to discriminate some postural interferences of the tongue. At the same time the results suggest the relationship between cervical ROM and stability. These results suggest the necessity to study more in deep this phenomenon with other specific class of subjects

Ordinary versus PT-symmetric ϕ3\phi^3 quantum field theory

A quantum-mechanical theory is PT-symmetric if it is described by a Hamiltonian that commutes with PT, where the operator P performs space reflection and the operator T performs time reversal. A PT-symmetric Hamiltonian often has a parametric region of unbroken PT symmetry in which the energy eigenvalues are all real. There may also be a region of broken PT symmetry in which some of the eigenvalues are complex. These regions are separated by a phase transition that has been repeatedly observed in laboratory experiments. This paper focuses on the properties of a PT-symmetric $ig\phi^3$ quantum field theory. This quantum field theory is the analog of the PT-symmetric quantum-mechanical theory described by the Hamiltonian $H=p^2+ix^3$, whose eigenvalues have been rigorously shown to be all real. This paper compares the renormalization-group properties of a conventional Hermitian $g\phi^3$ quantum field theory with those of the PT-symmetric $ig\phi^3$ quantum field theory. It is shown that while the conventional $g\phi^3$ theory in $d=6$ dimensions is asymptotically free, the $ig\phi^3$ theory is like a $g\phi^4$ theory in $d=4$ dimensions; it is energetically stable, perturbatively renormalizable, and trivial.Comment: 13 pages, 2 figure