arXiv subjects

L. Selbuz

Publications and source records attributed to L. Selbuz.

6 recordsLinked to original sources

arXiv2025

Explaining Belle Data on $B\to K^{(*)}\nu\bar{\nu}$ Decays via Dark $Z$ Resonances

The Belle II Collaboration reported the first measurement on ${\rm Br}(B^+\rightarrow K^+\nu\bar{\nu})$, which lies 2.7$\sigma$ away from the Standard Model expectation. This result may be manifestation of new physics beyond the Standard Model. In present work, motivated by the Belle II measurement, we investigate the effect of a dark photon/dark $Z$ on the rare $B$ meson decay $B^+\rightarrow K^+\nu\bar{\nu}$ and show that the ${\rm Br}(B^+\rightarrow K^+\nu\bar{\nu})$ excess from Belle II over the Standard Model expectation explained by the appearance of the dark $Z$ especially in resonances. We also derive constraints on various parameters of the two-Higgs-doublet model extended with a dark Abelian gauge group, in light of the measurement of the ${\rm Br}(B^+\rightarrow K^+\nu\bar{\nu})$ by the Belle-II Collaboration as well as the upper bound on ${\rm Br}(B^0\rightarrow K^{*0}\nu\bar{\nu})$ decay, set by the Belle data. Our results indicate that there exists a common region where both experimental results are satisfied for a dark $Z$ mass around 4.5 GeV with suitable values of the other parameters.

hep-ph↗

arXiv2022

Constraining Non-minimal Dark Sector Scenarios with the COHERENT Neutrino Scattering Data

Abelian dark sector scenarios embedded into the two-Higgs doublet model are scrutinized within the Coherent Elastic Neutrino-Nucleus Scattering (CE$\nu$NS) experiment, which was first measured by the COHERENT Collaboration in 2017 with an ongoing effort to improve it since then and recently released data for the CsI target in 2022. In the theoretical framework, it is assumed that there is a $U(1)$ gauge group in the dark sector with a non-zero kinetic mixing with the hypercharge field. The COHERENT data for the targets CsI and liquid argon (LAr) are treated in both single and multi bin bases to constrain the multi dimensional parameter space, spanned by the dark gauge coupling, kinetic mixing parameter and the dark photon mass, of totally seven different representative scenarios which are also compared and contrasted among each other to find out about the most sensitive one to the data. The effect of refined quenching factor is also addressed.

hep-ph↗

arXiv2021

Heavy $Z^\prime$ Bosons in the Secluded $U(1)^\prime$ Model at Hadron Colliders

We study $Z'$ phenomenology at hadron colliders in an $U(1)'$ extended MSSM. We choose a $U(1)'$ model with a secluded sector, where the tension between the electroweak scale and developing a large enough mass for $Z'$ is resolved by incorporating three additional singlet superfields into the model. We perform a detailed analysis of the production, followed by decays, including into supersymmetric particles, of a $Z'$ boson with mass between 4 and 5.2 TeV, with particular emphasis on its possible discovery. We select three different scenarios consistent with the latest available experimental data and relic density constraints, and concentrate on final signals with two leptons, four leptons and six leptons. Including the SM background from processes with two, three or four vector bosons, we show the likelihood of observing a $Z^\prime$ boson is not promising for the HL-LHC at 14 TeV. While at 27 and 100 TeV, the situation is more optimistic, and we devise specific benchmark scenarios which could be observed.

hep-ph↗

arXiv2010

Tau sleptons and Tau sneutrino Decays in MSSM under the Cosmological Bounds

We present the numerical investigation of the fermionic two-body decays of tau sleptons $\tilde τ_{1,2}$ and $τ$ sneutrino in the Minimal Supersymmetric Standard Model with complex parameters. In the analysis we particularly take into account the cosmological bounds imposed by WMAP data. We plot the CP-phase dependences for each fermionic two-body channel of $\tilde τ_{1,2}$ and $τ$ sneutrino and speculate about the branching ratios and total (two-body) decay widths. We find that the phase dependences of the decay widths of the third family sleptons are quite significant which can provide viable probes of additional CP sources. We also draw attention to the polarization of the final-state tau in the $ \tilde τ_{1,2}$ decays.

hep-ph↗

arXiv2007

Squark Decays in MSSM Under the Cosmological Bounds

We present the numerical investigation of the fermionic two-body decays of squarks in the Minimal Supersymmetric Standard Model with complex parameters. In the analysis we particularly take into account the cosmological bounds imposed by WMAP data. We find that the phase dependences of the decay widths of the third family squarks, as well as those of the first and second families, are quite significant which can provide viable probes of additional CP sources. We plot the CP phase dependences for each fermionic two-body decay channel of squarks $\tilde q_i$ (i=1,2, q=u,d;c,s;t,b) and speculate about the branching ratios and total (two-body) decay widths.

hep-ph↗

arXiv2006

Top and Bottom Squarks Decays under Cosmological Bounds

We investigate the fermionic decays of top squarks tilde t_{1,2} and bottom squarks tilde b_{1,2}$ in the Minimal Supersymmetric Standard Model with complex parameters M_1, mu, A_t and A_b . In the analysis we particularly take into account the cosmological bounds imposed by WMAP data. We plot the CP phase dependences of stop and sbottom decay widths.

hep-ph↗