It belongs to a class of particles known as bosons, characterized by an integer value of their spin quantum number. The Higgs field is a quantum field that has a non-zero value in its ground state. The Higgs boson is the quantum of the Higgs field, just as the photon is the quantum of the electromagnetic field. The Higgs boson has a large mass however, which is why a high energy accelerator is needed to observe it.
The existence of the Higgs boson was predicted by the Standard Model to explain how spontaneous breaking of electroweak symmetry (the Higgs mechanism) takes place in nature, which in turn explains why other elementary particles have mass. It is expected to have no spin and no electric or color charge, and it interacts with other particles through Yukawa-type interactions between the various fermions and the field. Alternative sources of the Higgs mechanism that do not need the Higgs boson are also possible
The Standard Model predicts the existence of a field, called the Higgs field, which has a non-zero amplitude in its ground state; i.e. a non-zero vacuum expectation value. The existence of this non-zero vacuum expectation spontaneously breaks electroweak gauge symmetry which in turn gives rise to the Higgs mechanism. It is the simplest process capable of giving mass to the gauge bosons while remaining compatible with gauge theories. The field can be pictured as a pool of molasses that "sticks" to the otherwise mlassless fundamental particles that gravel through the field, converting them into particles with mass that form (for example) the components of atoms. Its quantum would be a scalar bosonIn the Standard Model, the Higgs field consists of two neutral and two charged component fields. Both of the charged components and one of the neutral fields are Goldstone bosons, which act as the longitudinal third-polarization components of the massive W+, W–, and Z bosons. The quantum of the remaining component.
In the paper by Higgs the boson is massive, and in a closing sentence Higgs writes that "an essential feature" of the theory "is the prediction of incomplete multiplets of scalar and vector bosons". In the paper by GHK the boson is massless and decoupled from the massive states. In reviews dated 2009 and 2011, Guralnik states that in the GHK model the boson is massless only in a lowest-order approximation, but it is not subject to any constraint and acquires mass at higher orders, and to give a complete analysis
The results of searching for the Higgs boson are expected to provide evidence about how this is realized in nature.

In theory the mass of the Higgs boson can be estimated indirectly. In the Standard Model, the Higgs boson has a number of indirect effects; most notably, Higgs loops result in tiny corrections to masses of W and Z bosons. Precision measurements of electroweak parameters, such as the Fermi constant and masses of W/Z bosons, can be used to constrain the mass of the Higgs. As of July 2011, the precision electroweak measurements tell us that the mass of the Higgs boson is lower than about 161 GeV/c2 at 95% confidence level (CL). This upper bound increases to 185 GeV/c2 when including the LEP-2 direct search lower bound of 114.4 GeV/c2.[26] These indirect constraints rely on the assumption that the Standard Model is correct. It may still be possible to discover a Higgs boson above 185 GeV/c2 if it is accompanied by other particles beyond those predicted by the Standard Model.

The minimal Standard Model as described above contains only one complex isospin Higgs doublet, however, it also is possible to have an extended Higgs sector with additional doublets or triplets. The non-minimal Higgs sector favored by theory are the two-Higgs-doublet models (2HDM), which predict the existence of a quintet of scalar particles: two CP-even neutral Higgs bosons h0 and H0, a CP-odd neutral Higgs boson A0, and two charged Higgs particles H±. The key method to distinguish different variations of the 2HDM models and the minimal SM involves their coupling and the branching ratios. The so called Type-I model has one higgs doublet coupling to up and down quarks, . This model has two interesting limits, in which the lightest higgs doesn't couple to either fermions (fermiophobic) or gauge bosons (gauge-phobic). In the 2HDM of Type-II, one Higgs doublet only couples to up-type quarks


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