Phenomenology of scalar leptoquarks

Abstract

We study the simplest renormalizable scalar leptoquark models where the standard model is augmented only by one additional scalar representation of SU(3) x SU(2) x U(1). The requirement that there be no proton decay from renormalizable interactions singles out two such models, one of which exhibits an unusual top mass enhancement of the mu -> e gamma decay rate. We analyze the phenomenology of the model with the unusual top mass enhancement of loop level chirality changing charged lepton processes in the light of existing and upcoming experiments. Both of the models that do not allow proton decay from renormalizable interactions have dimension five operators that, even if suppressed by the Planck scale, can give rise to an unacceptably high level of baryon number violation. We discuss symmetries that can forbid these dimension five operators.Comment: 7 pages, 9 figure

Model-discriminating power of lepton flavor violatingτdecays

“…Many scenarios of physics beyond the SM predict rates for LFV processes of charged leptons within the reach of present and future experiments. Some examples are: the SM with additional right-handed heavy Majorana neutrinos or with left-handed and right-handed neutral singlets [2], supersymmetric models [3][4][5][6][7][8][9][10][11][12][13][14], left-right symmetric models [15,16], technicolor models with non-universal Z exchange [17], multi-Higgs doublet models [18][19][20][21][22][23], leptoquark models [24][25][26], models with heavy vector-like leptons [27][28][29][30], and, the Littlest Higgs model with T-parity [31,32]. It is obvious then that if LFV transitions among charged leptons are observed at some point, it will be a challenging task to disentangle all the possible NP candidates.…”

Study of the rare semileptonic decaysBd0→K*l+Sahoo1, Mohanta2 2016Phys. Rev. D471420View full textAdd to dashboardCite

“…Scalar leptoquarks are encountered in extended technicolor models and models with compositeness of quark and lepton [16,17] at TeV scale. However, in this case the bounds from proton decays may not be relevant and leptoquarks may give signatures in other low energy processes [18]. The phenomenology of scalar leptoquark and the contribution to new physics has been quite well studied in the literature [18][19][20][21][22].…”

Constraints on leptoquark models from IceCube data

“…However, there exists dimension five operators that may lead to proton decay. But these dimension five operators can be avoided by the imposition of appropriate discrete symmetries [5]. The constraints on these types of LQs coming from charged lepton sector, e.g., via the processes µ → eγ, conversion of µ to e and electric dipole moment of the electron, have been discussed in [5].…”

“…The scalars of this model give rise to this symmetry breaking and also to provide Yukawa couplings to generate fermion masses. They do not couple to the type of fermion-bilinears [5](Q L · L , Q L ·Q L etc.) which give rise to proton decay.…”

“…These arise in grand unified theories like SO (10), SU (5) or Pati-Salam SU (4) and are expected to have masses in the GUT scale in order to not cause rapid proton decay. Models with low scale leptoquarks have been considered [1][2][3][4] which do not lead to rapid proton decays.…”