Servizio Comunitario di Informazione in materia di Ricerca e Sviluppo - CORDIS

Final Report Summary - FPTLHC (From FLAVOR precision tests to LHC discoveries)

The field of high energy physics has entered into a new era. The LHC experiments provide us with an invaluable data on the fundamental laws of nature, in particular discovered the standard model (SM) celebrated Higgs boson.
What is left unanswered so far is the question whether electroweak symmetry breaking (EWSB) is a natural or finely tuned phenomena. Any known natural solution to this fine tuning problem involves new particles near the EWSB scale. Furthermore, the observed hierarchy in the SM flavor parameters (the flavor puzzle) calls for a fundamental explanation. While the flavor puzzle does not come with with an associated scale to it, we find it likely that new physics (NP) discovery at the LHC would lead to insight related to flavor physics. Information related to flavor physics typically carry with it understanding of short distance phenomena, well above the reach of near future experiments, and thus of invaluable nature. In addition, the most severe fine tuning problem is due to the top large Yukawa coupling. This by itself leads to a potential linkage between issues related to EWSB and flavor physics. Furthermore, within the SM, every fermion mass, m_f, is induced by the product v x y_f, where y_f denotes the fermion coupling to the Higgs boson, which corresponds to the strength of the Higgs force felt by the fermion f, and v is the Higgs vacuum expectation value (VEV) that sets the weak scale. The setup leads to a unique construct. Without testing this relation experimentally, we cannot answer the following fundamental question: is the Higgs mechanism responsible for the origin of masses of all matter constituents? In fact, it is possible that the strength of these Higgs-to-light-fermion interactions is far stronger than the above prediction, or that the light fermion masses are not due to the Higgs mechanism at all, resulting in much smaller couplings. Both cases lead to an alternative understanding of the flavor puzzle and to the establishment of new physics.

Our knowledge about the unexplored LHC energy regime is coming mainly from indirect precision measurements. One cannot overemphasize the importance of correctly interpreting indirect data. For instance, it led, to predicting the existence and mass scale of the charm and top quarks. Low energy measurements guide us in our search for beyond the standard model (SM) dynamics at the LHC. The absence of deviation from the SM predictions related to flavor changing neutral current (FCNC) processes lead us to look for NP models with highly non-generic flavor structure and furthermore, render a simplified NP searching techniques at the LHC. We have shown how to reinterpret the existing data under two radical assumptions. The first is assuming that the new physics sector respect a SM-like flavor structure, a framework that is generically denoted as minimal flavor violation. The second is assuming that the NP flavor scale carry a structure vastly different than the SM, namely its spectrum being anarchical. In particular, the masses and couplings of the first two generation are allowed to be split. We have provided various studies of this possibility via model building, studies of implications for low energy flavor precision observables, Higgs rate, and examined the implications of such a scenario at the LHC.
In the very last period of the grant two major advances were obtained in the first we have provided a phenomenological description of the recently observed diphoton excess at invariant mass of 750 GeV both in ATLAS and CMS. In the second we have shown that precision atomic physics can potentially probe the atomic Higgs force in precision that might surpass that of the LHC and LEP collider experiments.

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