Speaker
Description
The charm sector offers considerable scope for exploring new physics (NP) beyond standard model (SM). Rare charm decays which proceed through the flavour changing neutral current (FCNC) transitions are effectively suppressed due to the Glashow-Iliopoulos-Maiani mechanism. This makes charm decays sensitive to NP effects [1]. Several phenomenological studies have been done to look for NP in the charm sector. The experimental upper limits of some decays undergoing $c→ul^+ l^-$ transition such as $D^+ → \pi^+ \mu^+ \mu^-$, $D^+_s → K^+ \mu^+ \mu^-$ , $D^+ → \rho^+ \mu^+ \mu^-$ are of the order of $10^{-8}$, $10^{-7}$ and $10^{-4}$ respectively [2]. These charm decays have been explored for NP effects through leptoquark model [3, 4], SUSY models [4] and $Z'$ model [3-5]. In non-universal $Z'$ model, the rare FCNC decays occur at tree level and they are mediated by a new gauge boson particle, the $Z'$ boson. In this work, we shall look for possibilities of NP due to the effects of $Z'$ boson on the rare charm decays $D→\rho e^+ e^-$, which proceed through $c→ul^+ l^-$ quark transition. The $Z'$ boson couples with both quarks as well as leptons. We shall modify the Wilson coefficients by incorporating the NP couplings. We shall estimate the branching fractions and forward backward asymmetries in $Z'$ model and compare them with their corresponding SM values. Since $D→\rho e^+ e^-$ decays are FCNC decays undergoing $c→ul^+ l^-$ transition, we expect these decays to be sensitive to the effects of $Z'$ boson.
Acknowledgement
M. Mandal acknowledges Department of Science and Technology, Govt. of India for providing the INSPIRE Fellowship (IF200277) during her research.
References
1. P. Colangelo, F. D. Fazio and F. Loparco, $c→u \nu \nu ̅ $ transitions of $B_c$ mesons: 331 model facing Standard Model null tests, Phys. Rev. D 104, 115024 (2021) [arXiv:2107.07291 [hep-ph]].
2. S. Navas et al., The Review of Particle Physics (2024), Phys. Rev. D 110, 030001 (2024).
3. S. Sahoo and R. Mohanta, New physics effects in charm meson decays involving $c→ul^+ l^- (l_i^± l_j^∓)$ transitions, Eur. Phys. J. C 77, 344 (2017).
4. R. Bause, M. Golz, G. Hiller and A. Tayduganov, The new physics reach of null tests with $D→\pi ll$ and $D_s→Kll$ decays, Eur. Phys. J. C 80, 65 (2020).
5. M. Mandal, S. Biswas, S. Mahata and S. Sahoo, Searching for new physics in $c→u$ transitions with nonuniversal $Z'$ model, Int. J. Mod. Phys. A 39, 2450063 (2024).
| Field of contribution | Phenomenology |
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