
Abbas, G. (2016). Rightrightleft extension of the Standard Model. Mod. Phys. Lett. A, 31(19), 1650117–10pp.
Abstract: A rightrightleft extension of the Standard Model is proposed. In this model, SM gauge group SU(2)(L) circle times U(1)(Y) is extended to SU(2)(L) circle times SU(2)(R) circle times SU(2)'(R) circle times SU(2)'(L) circle times U(1)(Y). The gauge symmetries SU(2)'(R), SU(2)'(L) are the mirror counterparts of the SU(2)(L) and SU(2)(R), respectively. Parity is spontaneously broken when the scalar Higgs fields acquire vacuum expectation values (VEVs) in a certain pattern. Parity is restored at the scale of SU(2)'(L). The gauge sector has a unique pattern. The scalar sector of the model is optimum, elegant and unique.



Abbas, G., Abyaneh, M. Z., Biswas, A., Gupta, S., Patra, M., Rajasekaran, G., et al. (2016). High scale mixing relations as a natural explanation for large neutrino mixing. Int. J. Mod. Phys. A, 31(17), 1650095–47pp.
Abstract: The origin of small mixing among the quarks and a large mixing among the neutrinos has been an open question in particle physics. In order to answer this question, we postulate general relations among the quarks and the leptonic mixing angles at a high scale, which could be the scale of Grand Unified Theories. The central idea of these relations is that the quark and the leptonic mixing angles can be unified at some high scale either due to some quark lepton symmetry or some other underlying mechanism and as a consequence, the mixing angles of the leptonic sector are proportional to that of the quark sector. We investigate the phenomenology of the possible relations where the leptonic mixing angles are proportional to the quark mixing angles at the unification scale by taking into account the latest experimental constraints from the neutrino sector. These relations are able to explain the pattern of leptonic mixing at the low scale and thereby hint that these relations could be possible signatures of a quark lepton symmetry or some other underlying quark lepton mixing unification mechanism at some high scale linked to Grand Unified Theories.



Abbas, G., ZahiriAbyaneh, M., & Srivastava, R. (2017). Precise predictions for Dirac neutrino mixing. Phys. Rev. D, 95(7), 075005–7pp.
Abstract: The neutrino mixing parameters are thoroughly studied using renormalization group evolution of Dirac neutrinos with recently proposed parametrization of the neutrino mixing angles referred to as “highscale mixing relations.” The correlations among all neutrino mixing and CP violating observables are investigated. The predictions for the neutrino mixing angle. 23 are precise, and could be easily tested by ongoing and future experiments. We observe that the highscale mixing unification hypothesis is incompatible with Dirac neutrinos due to updated experimental data.



Abbas, G. (2017). Low scale leftrightrightleft symmetry. Phys. Rev. D, 95(1), 015029–8pp.
Abstract: We propose an effective leftrightrightleft model with a parity breaking scale around a few TeV. One of the main achievements of the model is that the mirror fermions as well as the mirror gauge sector simultaneously could be at TeV scale. It is shown that the most dangerous quadratic divergence of the SM Higgs boson involving the top quark in the loop is naturally suppressed, and begins at three loop. The model postpones the finetuning of the mass of the SM Higgs boson up to a sufficiently high scale. The model explains the smallness of the neutrino masses whether they are Dirac or Majorana. Furthermore, the strong CP phase is zero in this model.



Biswas, A., Sinha, N., & Abbas, G. (2015). Nonleptonic decays of charmed mesons into two pseudoscalars. Phys. Rev. D, 92(1), 014032–16pp.
Abstract: We examine the role of resonant coupled channel final state interactions (FSIs), as well as weak annihilation and exchange contributions, in explaining all the twobody hadronic D > PP decay modes. In the ununitarized amplitudes we include modified Wilson coefficients with nonfactorizable corrections as parameters. For the hadronic form factors, the zseries expansion method is used to get the q(2) dependence. The FSI effects are incorporated via a phenomenological approach with widths of resonances to various channels taken from observations where available, and others as additional parameters to be determined from fits of all the theoretical rates to the measured ones. Our results for the rather hard to explain D0 > K+K, pi(+)pi() are in agreement with measured values. We demonstrate that both weak exchange and FSI effects are required to get the correct branching ratio for the D0 > K0(K) over bar (0) mode. Using our unitarized amplitudes we evaluate the strong phase difference between the amplitudes for D0 > Kpi(+) and D0 > K+pi() and find it to be in complete agreement with the recent BES III result.



Abbas, G., Celis, A., Li, X. Q., Lu, J., & Pich, A. (2015). Flavourchanging top decays in the aligned twoHiggsdoublet model. J. High Energy Phys., 06(6), 005–26pp.
Abstract: We perform a complete oneloop computation of the twobody flavourchanging top decays t > ch and t > cV (V = gamma, Z), within the aligned twoHiggsdoublet model. We evaluate the impact of the model parameters on the associated branching ratios, taking into account constraints from flavour data and measurements of the Higgs properties. Assuming that the 125 GeV Higgs corresponds to the lightest CPeven scalar of the CPconserving aligned twoHiggsdoublet model, we find that the rates for such flavourchanging top decays lie below the expected sensitivity of the future highluminosity phase of the LHC. Measurements of the Higgs signal strength in the diphoton channel are found to play an important role in limiting the size of the t > ch decay rate when the charged scalar of the model is light.

