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Maurizio Consoli

Publications and source records attributed to Maurizio Consoli.

12 recordsLinked to original sources
arXiv2024

Second resonance of the Higgs field: motivations, experimental signals, unitarity constraints

Perturbative calculations predict that the Standard Model (SM) effective potential should have a new minimum, well beyond the Planck scale, much deeper than the electroweak vacuum. As it is not obvious that gravitational effects can get so strong to stabilize the potential, most authors have accepted the metastability scenario in a cosmological perspective. This perspective is needed to explain why the theory remains trapped into our electroweak vacuum, but requires to control the properties of matter in the extreme conditions of the early universe. Alternatively, one can consider the completely different idea of a non-perturbative effective potential which, as at the beginning of the SM, is restricted to the pure $Φ^4$ sector yet consistent with the now existing analytical and numerical studies. In this approach, where the electroweak vacuum is the lowest-energy state, besides the resonance of mass $m_h=125$ GeV defined by the quadratic shape of the potential at its minimum, the Higgs field should exhibit a second resonance with mass $690\pm10({\rm stat})\pm20({\rm sys})$ GeV associated with the zero-point energy determining the potential depth. Despite its large mass, this would couple to longitudinal $W$s with the same typical strength as the low-mass state at 125 GeV and represent a relatively narrow resonance of width $Γ_H=30÷38$ GeV, mainly produced at LHC by gluon-gluon fusion. So it is interesting that, in the LHC data, one can find various indications for a new resonance in the expected mass range with a non-negligible statistical significance. As this could become an important new discovery by just adding two missing samples of RUN2 data, we outline further refinements of the theoretical predictions that could be obtained by implementing unitarity constraints, in the presence of fermion and gauge fields, with coupled-channel calculations used for meson spectroscopy.

hep-ph↗
arXiv2024

A new 700 GeV scalar in the LHC data?

As an alternative to the metastability of the electroweak vacuum, resulting from perturbative calculations, one can consider a non-perturbative effective potential which, as at the beginning of the Standard Model, is restricted to the pure $Φ^4$ sector yet consistent with the known analytical and numerical studies. In this approach, where the electroweak vacuum is now the lowest-energy state, besides the resonance of mass $m_h=$ 125 GeV defined by the quadratic shape of the potential at its minimum, the Higgs field should exhibit a second resonance with mass $(M_H)^{\rm Theor}=690\,(30)$ GeV associated with the zero-point energy determining the potential depth. In spite of its large mass, this resonance would couple to longitudinal $W$s with the same typical strength as the low-mass state at 125 GeV and represent a relatively narrow resonance, mainly produced at LHC by gluon-gluon fusion. In this Letter, we review LHC data suggesting a new resonance of mass $(M_H)^{\rm EXP} \sim 682\,(10)$ GeV, with a statistical significance that is far from negligible.

hep-ph↗
arXiv2024

Michelson-Morley Experiments: at the crossroads of Relativity, Cosmology and Quantum Physics

Quantum nonlocality would naturally fit into a version of relativity with a preferred reference system. However, acceptance of this idea has traditionally required experimental evidence. Namely, detecting in laboratory a small angular dependence of the velocity of light correlated to the cosmic motion of the Earth. Here, we summarize a new theoretical framework where the tiny, irregular residuals observed so far, from Michelson-Morley to current experiments of laser interferometry, can indeed be understood in terms of the Earth motion in the Cosmic Microwave Background observed directly with satellites in space. Our results, challenging the usual null interpretation, emphasize the central role of 'ether-drift' experiments for Relativity, Cosmology and Quantum Physics.

physics.gen-ph↗
arXiv2022

Second resonance of the Higgs field: more signals from the LHC experiments

Theoretical arguments and lattice simulations suggest that, beside the known resonance of mass $m_h=$ 125 GeV, the Higgs field might exhibit a second resonance with a larger mass $(M_H)^{\rm theor} = 690 \pm 10 ~({\rm stat}) \pm 20 ~({\rm sys})~ {\rm GeV}$ which, however, would couple to longitudinal W's with the same typical strength as the low-mass state at 125 GeV and thus represent a relatively narrow resonance mainly produced at LHC by gluon-gluon fusion. By looking for some evidence in the LHC data, we argue that the existence of a new resonance in the predicted mass region finds support in two analyses by ATLAS (searching for heavy resonances decaying into final states with 4 charged leptons or $γγ$ pairs) and in more recent CMS results (searching for heavy resonances decaying into a pair of $h(125)$ bosons or looking for $γγ$ pairs produced in $pp$ double-diffractive scattering). Since the correlation of these measurements is very small and since, having some definite theoretical prediction, local deviations from the pure background are not downgraded by the look-elsewhere effect, we emphasize the instability of the present situation that could probably be resolved by just adding two crucial, missing samples of RUN2 data.

hep-ph↗
arXiv2022

Quantum Non-Locality and the CMB: what Experiments say

"Non-Locality is most naturally incorporated into a theory in which there is a special frame of reference. One possible candidate for this special frame of reference is the one in which the Cosmic Microwave Background (CMB) is isotropic. However, other than the fact that a realistic interpretation of quantum mechanics requires a preferred frame and the CMB provides us with one, there is no readily apparent reason why the two should be linked" (L. Hardy). Starting from this remark we first argue that, given the present view of the vacuum, the basic tenets of Quantum Field Theory cannot guarantee that Einstein Special Relativity, with no preferred frame, is the physically realized version of relativity. Then, to try to understand the nature of the hypothetical preferred $Σ-$frame, we consider the so called ether-drift experiments, those precise optical measurements that try to detect in laboratory a small angular dependence of the two-way velocity of light and then to correlate this angular dependence with the direct CMB observations with satellites in space. By considering all experiments performed so far, from Michelson-Morley to the present experiments with optical resonators, and analyzing the small observed residuals in a modern theoretical framework, the long sought $Σ-$ frame tight to the CMB naturally emerges. Finally, if quantum non-locality reflects some effect propagating at vastly superluminal speed $v_{QI} \to \infty $, its ultimate origin could be hidden somewhere in the infinitely large speed $c_s \to \infty$ of the vacuum density fluctuations.

physics.gen-ph↗
arXiv2022

Experimental signals for a second resonance of the Higgs field

In the region of invariant mass 620$÷$740 GeV, we have analyzed the ATLAS sample of 4-lepton events that could indicate a new scalar resonance produced mainly via gluon-gluon fusion. These data suggest the existence of a new heavy state $H$ whose mass $660÷680$ GeV would fit well with the theoretical range $M_H = 690 \pm 10 ~({\rm stat}) \pm 20 ~({\rm sys})~ {\rm GeV}$ for the hypothetical second resonance of the Higgs field that has been recently proposed and which would couple to longitudinal W's with the same typical strength of the low-mass state at $125$ GeV. Since the total width $Γ_H$ is very poorly determined, to sharpen the analysis of the precious ATLAS data, we have considered a particular correlation between resonating peak cross section $σ_R(pp\to H \to 4l)$ and the ratio $γ_H=Γ_H/M_H$. This correlation should be nearly insensitive to the precise value of $Γ_H$ and mainly determined by the lower mass $m_h=$ 125 GeV. Equivalently, if this correlation holds true, one could also fit $m_h$ from the 4-lepton data in the high-mass range 620$÷$740 GeV. The result $(m_h)^{\rm fit} \sim (125 \pm 13)$ GeV reproduces the direct measurement of the Higgs particle mass and thus supports the idea that $m_h$ and $M_H$ are the masses of two different excitations of the same field. Therefore, if we combine with the excess at 680 GeV in the ATLAS $γγ$ distribution, there are now two signals for a new resonance in the same mass region. Even though, quantitatively, the global statistical significance of each effect is modest, still the sharp correlation $γ_H-σ_R$ in the 4-lepton channel should induce to consider seriously these indications.

hep-ph↗
arXiv2020

A resonance of the Higgs field at 700 GeV and a new phenomenology

It has been recently proposed that, besides the known resonance with mass $m_h\sim$ 125 GeV, the Higgs field could exhibit a new excitation with a larger mass $M_h$ related by $M^2_h\sim m^2_h \ln (Λ_s/M_h)$, where $Λ_s$ is the ultraviolet cutoff of the scalar sector. Lattice simulations of the propagator performed in the 4D Ising limit of the theory are consistent with this two-mass picture and lead to the estimate $M_h\sim 700$ GeV. In spite of its large mass, however, this heavier state would couple to longitudinal vector bosons with the same typical strength of the low-mass state and would thus represent a relatively narrow resonance. In this Letter we argue that this hypothetical new resonance would naturally fit with some excess of 4-lepton events which is observed by ATLAS around 680 GeV.

hep-ph↗
arXiv2020

The mass scales of the Higgs field

In the first version of the theory, with a classical scalar potential, the sector inducing SSB was distinct from the Higgs field interactions induced through its gauge and Yukawa couplings. We have adopted a similar perspective but, following most recent lattice simulations, described SSB in $λΦ^4$ theory as a weak first-order phase transition. In this case, the resulting effective potential has two mass scales: i) a lower mass $m_h$, defined by its quadratic shape at the minima, ~and~ ii) a larger mass $M_h$, defined by the zero-point energy. These refer to different momentum scales in the propagator and are related by $M^2_h\sim m^2_h \ln (Λ_s/M_h)$, where $Λ_s$ is the ultraviolet cutoff of the scalar sector. We have checked this two-scale structure with lattice simulations of the propagator and of the susceptibility in the 4D Ising limit of the theory. These indicate that, in a cutoff theory where both $m_h$ and $M_h$ are finite, by increasing the energy, there could be a transition from a relatively low value, e.g. $m_h$=125 GeV, to a much larger $M_h$. The same lattice data give a final estimate $M_h= 720 \pm 30 $ GeV which induces to re-consider the experimental situation at LHC. In particular an independent analysis of the ATLAS + CMS data indicating an excess in the 4-lepton channel as if there were a new scalar resonance around 700 GeV. Finally, the presence of two vastly different mass scales, requiring an interpolating form for the Higgs field propagator also in loop corrections, could reduce the discrepancy with those precise measurements which still favor large values of the Higgs particle mass.

hep-ph↗
arXiv2019

Two mass scales for the Higgs field?

In the original version of the theory, the driving mechanism for spontaneous symmetry breaking was identified in the pure scalar sector. However, this old idea requires a heavy Higgs particle that, after the discovery of the 125 GeV resonance, seems to be ruled out. We argue that this is not necessarily true. If the phase transition is weakly first order, as indicated by most recent lattice simulations, one should consider those approximation schemes that are in agreement with this scenario. Then, even in a simple one-component theory, it becomes natural to introduce two mass scales, say $M_h$ and $m_h$ with $m_h \ll M_h$. This resembles the coexistence of phonons and rotons in superfluid helium-4, which is the non-relativistic analogue of the scalar condensate, and is potentially relevant for the Standard Model. In fact, vacuum stability would depend on $M_h$ and not on $m_h$ and be nearly insensitive to the other parameters of the theory (e.g. the top quark mass). By identifying $m_h=125$ GeV, and with our previous estimate from lattice simulations $M_h= 754 \pm 20 ~\rm{(stat)} \pm 20 ~\rm{(syst)}$ GeV, we thus get in touch with a recent, independent analysis of the ATLAS + CMS data which claims experimental evidence for a scalar resonance around $700$ GeV.

hep-ph↗
arXiv2011

On the low-energy spectrum of spontaneously broken Φ^4 theories

The low-energy spectrum of a one-component, spontaneously broken Φ^4 theory is generally believed to have the same simple massive form \sqrt{{\bf p}^2 + m^2_h} as in the symmetric phase where < Φ>=0. However, in lattice simulations of the 4D Ising limit of the theory, the two-point connected correlator and the connected scalar propagator show deviations from a standard massive behaviour that do not exist in the symmetric phase. As a support for this observed discrepancy, I present a variational, analytic calculation of the energy spectrum E_1({\bf p}) in the broken phase. This analytic result, while providing the trend E_1({\bf p})\sim \sqrt{{\bf p}^2 + m^2_h} at large |{\bf p}|, gives an energy gap E_1(0)< m_h, even when approaching the infinite-cutoff limit Λ\to \infty with that infinitesimal coupling λ\sim 1/\ln Λsuggested by the standard interpretation of "triviality" within leading-order perturbation theory. I also compare with other approaches and discuss the more general implications of the result.

hep-ph↗
arXiv1995

On the Value of R=Γ_h/Γ_l at LEP

We show that the present experimental LEP average R=Γ_h/Γ_l= 20.795 +- 0.040 is not unambiguous due to the presence of substantial systematic effects which cannot be interpreted within gaussian statistics. We find by Montecarlo simulation that the C.L. of the original LEP sample is only 3.8 \cdot 10^{-4}. We suggest that a reliable extimate of the true R-value is 20.60< R < 20.98 which produces only a very poor determination of the strong coupling constant at the Z mass scale, 0.10< α_s(M_z)< 0.15.

hep-ph↗