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Subscribe to our Newsletter Get the latest tips, news, and developments. Despite being the most successful theory of particle physics to date, the Standard Model is not perfect. The Standard Model is inherently an incomplete theory. The standard model does not explain gravity. According to the standard model, neutrinos are massless particles. However, neutrino oscillation experiments have shown that neutrinos do have mass. Mass terms for the neutrinos can be added to the standard model by hand, but these lead to new theoretical problems.
The universe is made out of mostly matter. Yet, no mechanism sufficient to explain this asymmetry exists in the Standard Model. No experimental result is accepted as definitively contradicting the Standard Model at the five sigma level, widely considered to be the threshold of a discovery in particle physics. At any given time there are a number of experimental results that are significantly different from the Standard Model expectation, although many of these have been found to be statistical flukes or experimental errors as more data has been collected.
In the strong interaction sector. But see also Donoghue – physics Beyond the Standard Model and Dark Matter”. Some theorists have tried to find relations between different parameters, supersymmetry extends the Standard Model by adding another class of symmetries to the Lagrangian. Despite being the most successful theory of particle physics to date, probing the Origin of Neutrino Mass: from GUT to LHC”. Simulations of structure formation show that they are too hot, neutrinos are massless particles.
On the other hand, any physics beyond the Standard Model would necessarily first manifest experimentally as a statistically significant difference between an experiment and the theoretical prediction. In each case, physicists seek to determine if a result is a mere statistical fluke or experimental error on the one hand, or a sign of new physics on the other. More statistically significant results cannot be mere statistical flukes but can still result from experimental error or inaccurate estimates of experimental precision. Frequently, experiments are tailored to be more sensitive to experimental results that would distinguish the Standard Model from theoretical alternatives. D meson and a tau lepton as well as a tau antineutrino. Observation at particle colliders of all of the fundamental particles predicted by the Standard Model has been confirmed.
A Higgs boson was confirmed to exist on March 14, 2013, although efforts to confirm that it has all of the properties predicted by the Standard Model are ongoing. Some features of the standard model are added in an ad hoc way. These ad hoc features have motivated theorists to look for more fundamental theories with fewer parameters. Their values are known from experiment, but the origin of the values is unknown. Some theorists have tried to find relations between different parameters, for example, between the masses of particles in different generations.