1,426 research outputs found
Non-renormalizable Yukawa Interactions and Higgs Physics
We explore a scenario in the Standard Model in which dimension four Yukawa
couplings are either forbidden by a symmetry, or happen to be very tiny, and
the Yukawa interactions are dominated by effective dimension six interactions.
In this case, the Higgs interactions to the fermions are enhanced in a large
way, whereas its interaction with the gauge bosons remains the same as in the
Standard Model. In hadron colliders, Higgs boson production via gluon gluon
fusion increases by a factor of nine. Higgs decay widths to fermion
anti-fermion pairs also increase by the same factor, whereas the decay widths
to photon photon and gamma Z are reduced. Current Tevatron exclusion range for
the Higgs mass increases to ~ 142-200 GeV in our scenario, and new physics must
appear at a scale below a TeV.Comment: 5 pages, 4 figure
Top quark asymmetry and Wjj excess at CDF from gauged flavor symmetry
We show that the scalar sector needed for fermion mass generation when the
flavor symmetry of the standard model is maximally gauged can consistently
explain two anomalies reported recently by the CDF collaboration - the
forward-backward asymmetry in t-tbar pair production, and the dijet invariant
mass in the Wjj channel. A pair of nearly degenerate scalar doublets with
masses in the range 150-200 GeV explain these anomalies, with additional
scalars predicted in the mass range 100-400 GeV. Consistency of such low scale
flavor physics with flavor changing processes is shown, and expectations for
the LHC are outlined.Comment: 4 pages, RevTeX, 3 figure
Top SU(5) Models: Baryon and Lepton Number Violating Resonances at the LHC
We propose the minimal and renormalizable non-supersymmetric top SU(5) models
where the gauge symmetry
is broken down to the Standard Model (SM) gauge symmetry at the TeV scale. The
first two families of the SM fermions are charged under while the third family is charged under SU(5). In the
minimal top SU(5) model, we show that the quark CKM mixing matrix can be
generated via dimension-five operators, and the proton decay problem can be
solved by fine-tuning the coefficients of the higher dimensional operators at
the order of . In the renormalizable top SU(5) model, we can explain
the quark CKM mixing matrix by introducing vector-like particles, and we do not
have proton decay problem. The models give rise to leptoquark and diquark gauge
bosons which violate both lepton and baryon numbers involving the third family
quarks and leptons. The current experimental limits for these particles is well
below the TeV scale. We also discuss the productions and decays of these new
gauge bosons, and their ensuing signals, as well as their reach at the LHC.Comment: 30 pages, 13 figure
New signals for vector-like down-type quark in of
We consider the pair production of vector-like down-type quarks in an
motivated model, where each of the produced down-type vector-like quark decays
into an ordinary Standard Model light quark and a singlet scalar. Both the
vector-like quark and singlet scalar appear naturally in the model with
masses at the TeV scale with a favorable choice of symmetry breaking pattern.
We focus on the non-standard decay of the vector-like quark and the new scalar
which decays to two photons or two gluons. We analyze the signal for the
vector-like quark production in the channel and show how the
scalar and vector-like quark masses can be determined at the Large Hadron
Collider.Comment: 25 pages, 11 figures, 6 tables. arXiv admin note: text overlap with
arXiv:1607.0081
Quark lepton unification in higher dimensions
The idea of unifying quarks and leptons in a gauge symmetry is very
appealing. However, such an unification gives rise to leptoquark type gauge
bosons for which current collider limits push their masses well beyond the TeV
scale. We present a model in the framework of extra dimensions which breaks
such quark-lepton unification symmetry via compactification at the TeV scale.
These color triplet leptoquark gauge bosons, as well as the new quarks present
in the model, can be produced at the LHC with distinctive final state
signatures. These final state signals include high p_T multi-jets and
multi-leptons with missing energy, monojets with missing energy, as well as the
heavy charged particles passing through the detectors, which we also discuss
briefly. The model also has a neutral Standard Model singlet heavy lepton which
is stable, and can be a possible candidate for the dark matter.Comment: 28 pages, 5 eps figure
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