Study of Non-Standard Interactions in Rare Mesonic Decays

Abstract

Study of Non-Standard Interactions in Rare Mesonic Decays The study of rare decays and search for new physics are entangled with each other. The importance of these decays highly increases if the decay products contain dineutrinos in their nal state due to its theoretically cleanest nature. In this scenario, for detailed illustration, we will use the pure and semileptonic rare decays of pseudoscalar mesons with missing energy and study the role of NSIs on Br and non standard parameters qL and qR by using model-independent analysis. We investigate the long distance dominated (in the standard model) processes D+ s ! K+ , D0 ! 0 and short distance dominated (in the standard model) D+ s ! D+ decays for the purpose of non-standard neutrino interactions (NSIs). The branching ratios of D+ s ! K+ ; D0 ! 0 and D+ s ! D+ decays are calculated in the framework of NSIs. The values of non- standard parameters uL , dL and dL for = = e or are found. Analysis of NSIs are extended by incorporating the second and third generations of quarks. We investigate that why the only available non-standard parameter constraints in the literature are uL and dL ;and why we are unable to nd bounds on non-standard parameters, pertaining to second and third generation, i.e. bL , sL ; cL and tL . Contrary to quark sector, in charged lepton sector, non- standard parameters eL , L and L , relevant to second and third generations, are good constraints. We investigate D+ s ! K+ ; D0 ! 0 and D+ ! + decays, in which avor changing neutral current (FCNC) involve only up type quarks, i.e. c 􀀀!u as an external particles and down type (d; s; b) quarks propagating in the loop. While in K+ ! + , D+ s ! D+ and B0 s 􀀀! B0 FCNC involves down type quarks, i.e. s 􀀀! d as an external lines, and up type (u; c; t) quark propagating inside the loop. The comparative study of the processes is done to check the generation sensitivity of the parameters of NSIs. We show that the dominant and comparable contribution of NSI is due to the rst and second generation, i.e. (u; d) and (c; s) quarks, while contribution of (t; b ) quarks is highly suppressed at radiative level, which is contrary to the SM. Furthermore, We present the comparative study of semileptonic and leptonic decays of Ds;D (D ! l , D ! l l , D s ! K l+ l􀀀 (v ) along with D ! Ml l ; M = ;K and ; = e; ) within the framework of R-parity violating Minimal Supersymmetric Standard Model (MSSM). The comparison shows that combination( i 0 ijq) and product couplings ( 0 qk 0 jq); contributing to the branching fractions of the processes D0 ! + 􀀀; D+ ! l , D+ s ! l ; D0 ! K􀀀e+ e; D s ! K l+ l􀀀 and D ! l+ l􀀀 (both for = and 6= ), are either consistent or comparable with the existing experimental data, when calculating in the R-parity violating SUSY model. Hence the golden channel for the study of new physics is provided. Contrary to that, processes like D0 ! e+e􀀀;D0 ! 􀀀l+ , D+ ! 0l+ and D0 ! K􀀀l+ are accommodated well in SM, but unfavorable for the study of new physics. We identify such type of processes in our analyses and single out the important ones, suitable for exploring in the current and future experiments.