
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.



Godbole, R. M., Maharathy, S. P., Mandal, S., Mitra, M., & Sinha, N. (2021). Interference effect in lepton number violating and conserving meson decays for a leftright symmetric model. Phys. Rev. D, 104(9), 095009–22pp.
Abstract: We study the effect of interference on the lepton number violating (LNV) and lepton number conserving (LNC) threebodymeson decaysM(1)(+)> l(i) (+) l(j)(+)pi(+/) that arise in a TeVscale leftright symmetric model (LRSM) with degenerate or nearly degenerate righthanded (RH) neutrinos. The LRSM contains three RH neutrinos and a RH gauge boson. The RH neutrinos with masses in the range of MN similar to (MeVfew GeV) can give resonant enhancement in the semileptonic LNV and LNC meson decays. In the case where only one RH neutrino contributes to these decays, the predicted new physics branching ratios of semileptonic LNV and LNC meson decaysM(1)(+)> l(i)(+) l(j)(+) pi() andM(+) 1 > l(i)(+)l(j)() pi(+) are equal. We find that with at least two RH neutrinos contributing to the process, the LNV and LNC decay rates can differ. Depending on the neutrino mixing angles and CPviolating phases, the branching ratios of LNVand LNC decay channelsmediated by the heavy neutrinos can be either enhanced or suppressed, and the ratio of these two rates can differ from unity.



Gola, S., Mandal, S., & Sinha, N. (2022). ALPportal majorana dark matter. Int. J. Mod. Phys. A, 37, 2250131–14pp.
Abstract: Axion like particles (ALPs) and righthanded neutrinos (RHNs) are two wellmotivated dark matter (DM) candidates. However, these two particles have a completely different origin. Axion was proposed to solve the strong CP problem, whereas RHNs were introduced to explain light neutrino masses through seesaw mechanisms. We study the case of ALP portal RHN DM (Majorana DM) taking into account existing constraints on ALPs. We consider the leading effective operators mediating interactions between the ALP and Standard Model (SM) particles and three RHNs to generate light neutrino masses through typeI seesaw. Further, ALPRHN neutrino coupling is introduced to generalize the model which is restricted by the relic density and indirect detection constraint.

