46694686
Light Higgs Boson Production in Two Higgs Doublets Models Type III
By using the Cheng, Sher and Yuan's anzats, we study the light Higgs Boson production associated with b quark production at TEVATRON using the 2HDM type III. We compare the simulations with experimental results coming from TEVATRON, finding valid ranges for the bb coupling. By using these results, we calculate the cross section for the process pp → bbh(bb) for the LHC collider.
118679107
New physics effects in Top quark interactions
The Top quark stands out as the heaviest elementary particle known today and it is expected to be sensitive to the mechanism that breaks the electroweak symmetry. In particular, the study of its couplings to the electroweak gauge bosons is important as it a way to test different models beyond the SM. We review the status of Top quark couplings with the W and Z bosons, as well as FCNC couplings.
122784148
Anomalous top magnetic couplings
The real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the tbW vertex in the Standard Model (SM) are computed.
15573535
NEW PHYSICS EFFECTS IN THE FLAVOR-CHANGING NEUTRAL COUPLINGS OF THE TOP QUARK
We survey the flavor-changing neutral couplings (FCNC) of the top quark predicted by some extensions of the Standard Model: THDM, SUSY, Left–Right symmetric, TC2, 331, and models with extra quarks. Since the expected sensitivity of the LHC and ILC for the tcV (V = γ, g, Z) and tcH couplings is of order of a few percent, we emphasize the importance of any new physics effect that gives a prediction for these FCNC couplings within this limit. We also review the constraints imposed on these couplings from low-energy precision measurements.
124002542
Quark masses and mixing in $SU\left(3\right)_{C}\otimes SU\left(3\right)_{L}\otimes U\left(1\right)_{X}\otimes S_{3}$ models
By imposing a specific $S_{3}$ discrete symmetry for fermions and scalars, we extend the group of the model based on the gauge symmetry $SU(3)_{C}\otimes SU(3)_{L}\otimes U(1)_{X}$. We found that after the symmetry breaking of the continuous group, all the down type quarks acquire tree level masses, while in the up sector only the top quark and a new heavy T quark obtain masses at tree level. By imposing hierarchical Yukawa couplings between the ordinary down-type quarks and new heavy down-type quarks, we may explain the relation $m_{d}<<m_{s}<<m_{b}$. The massless up-type quarks get small mass terms through effective six dimensional operators according to the gauge and discrete symmetries. In particular, the smallness of the u quark can be understood by a small deviation in the universality of the dimensionless couplings associated to the effective operators. We also obtain with only four free parameters, the magnitudes of the CKM matrix elements and the Jarlskog invariant, within experimental error values.
53625847
Top quark tensor couplings
We compute the real and imaginary parts of the one-loop electroweak contributions to the left and right tensorial anomalous couplings of the tbW vertex in the Standard Model (SM). For both tensorial couplings we find that the real part of the electroweak SM correction is close to 10% of the leading contribution given by the QCD gluon exchange. We also find that the electroweak real and imaginary parts for the anomalous right coupling are almost of the same order of magnitude. The one loop SM prediction for the real part of the left coupling is close to the 3σ discovery limit derived from b → sγ. Besides, taking into account that the predictions of new physics interactions are also at the level of a few percents when compared with the one loop QCD gluon exchange, these electroweak corrections should be taken into account in order to disentangle new physics effects from the standard ones. These anomalous tensorial couplings of the top quark will be investigated at the LHC in the near future where sensitivity to these contributions may be achieved.
118371403
Phenomenological aspects of the exotic T quark in 331 models
In the context of 331 models we analyze the phenomenology of exotic T quarks with electric charge 2/3. We establish bounds for the corresponding masses and mixing angles and study the decay modes T→bW, tZ and qH. It is found that the decays into scalars are strongly dependent on the model parameters and can be the dominant ones in a scenario with approximate flavor symmetry.