arXiv subjects

M. Chakraborti

Publications and source records attributed to M. Chakraborti.

9 recordsLinked to original sources

arXiv2025

GUT-based NMSSM with Singlino Dark Matter: Describing the ATLAS/CMS Excesses

One of the main goals of the ongoing LHC program is the search for BSM physics, with EW SUSY partners still allowed with masses as low as a few hundred GeV. Over the last years, searches for the ``golden channel'', $pp \to \tilde\chi^0_2 \tilde\chi^\pm_1 \to \tilde\chi^0_1 Z^{(*)} \, \tilde\chi^0_1 W^{\pm (*)}$ show consistent excesses between CMS and ATLAS in the 2 soft-lepton and 3 soft-lepton plus missing $E_T$ searches, favoring mass scales of $m_{\tilde\chi^0_2} \approx m_{\tilde\chi^{\pm}_1} \ge 200$ GeV and $\Delta m_{21} := m_{\tilde\chi^0_2} - m_{\tilde\chi^0_1} \approx 20$ GeV. We analyze these excesses in the framework of the Next-to-Minimal Supersymmetric Standard Model (NMSSM). We assume a singlino dominated lighest neutralino, $\tilde\chi^0_1$, as our Dark Matter (DM) candidate. The second and third lightest neutralinos, $\tilde\chi^0_{2,3}$ are higgsino like, with the higgsino mixing parameter $\mu$ being smaller than the soft SUSY-breaking bino and wino masses, $M_1$ and $M_2$. In particular, we assume the approximate GUT relations $M_1 \sim M_2/2 \sim M_3/6$, yielding a gluino mass $m_{\tilde g} \sim M_3 \ge 2$ TeV, in agreement with the LHC search limits. The scalar masses are assumed to heavy and do not play a role in our analysis. We demonstrate that this scenario is in agreement with all relevant experimental constraints, comprising the DM direct detection limits and the upper limit on the DM relic density, the LHC searches for SUSY particles and additional Higgs bosons, as well as the LHC Higgs-boson rate measurements. This constitutes the first explanation of the soft-lepton excesses in a model with GUT relations among the soft SUSY-breaking parameters.

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arXiv2024

Probing 95 GeV Higgs in the 2HDM Type-III

The recent results reported by the CMS collaboration, indicating "bumps" in the $γγ$ and $ττ$ channels at $m_ϕ\approx 95$ GeV, provide interesting hints for new physics. We find that the lightest Higgs state of the general 2HDM (2HDM Type-III) can perfectly and simultaneously accommodate the two excesses alongside with the LEP long-standing anomaly observed in the $b\bar{b}$ channel while meeting all theoretical and experimental requirements. Furthermore, the study predicts an enhanced production process for the SM-like Higgs in $pp\to t\bar t H_{\rm SM}$, offering a testable hypothesis for future experiments.

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arXiv2022

Interdependence of the new "MUON G-2" Result and the $W$-Boson Mass

The electroweak (EW) sector of the Minimal Supersymmetric extension of the Standard Model (MSSM), assuming the lightest neutralino as Dark Matter (DM) candidate, can account for a variety of experimental results. In particular it can account for the discrepancy between the experimental result for the anomalous magnetic moment of the muon, $(g-2)_μ$, and its Standard Model (SM) prediction. The new "MUON G-2" result, combined with the older BNL result on $(g-2)_μ$, yields a deviation from the SM prediction of $Δa_μ = (25.1 \pm 5.9) \times 10^{-10}$, corresponding to $4.2~σ$. Using this updated bound, together with the other constraints, we calculate the MSSM prediction for the mass of the $W$ boson, $M_W$. We assume contributions only from the EW sector, with the colored sector of the MSSM taken to be heavy. We investigate five scenarios, distinguished by the mechanisms which yield a relic DM density in agreement with the latest Planck bounds. We find that with the new $(g-2)_μ$ result taken into account and depending on the scenario, values up to $M_W^{\mathrm{MSSM}} \lesssim 80.376~\mathrm{GeV}$ are reached. The largest values are obtained for wino DM and in the case of slepton co-annihilation, where points well within the $1\,σ$ range of the experimental world average of $M_W^{\mathrm{exp}} = 80.379 \pm~0.012~\mathrm{GeV}$ are reached, whereas the SM predicts a too small value of $M_W^{\mathrm{SM}} = 80.353~\mathrm{GeV}$. We analyze the dependence of $M_W^{\mathrm{MSSM}}$ on the relevant masses of the EW superpartners and demonstrate that future $M_W$ measurements, e.g. at the ILC, could distinguish between various MSSM realizations. Sizable contributions to $M_W^{\mathrm{MSSM}}$ are associated with a relatively light $\tildeχ^0_1$, accompanied by either a light chargino or a light smuon, setting interesting targets for future collider searches.

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arXiv2020

The "96 GeV excess" at the LHC

The CMS collaboration reported an intriguing \sim 3 sigma (local) excess at 96 GeV in the light Higgs-boson search in the diphoton decay mode. This mass coincides with a \sim 2 sigma (local) excess in the bb final state at LEP. We briefly review the proposed combined interpretations for the two excesses. In more detail we review the interpretation of this possible signal as the lightest Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). We show which channels have the best prospects for the discovery of additional Higgs bosons at the upcoming Run 3 of the LHC.

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arXiv2020

UV completion of an axial, leptophobic, $Z^\prime$

The $Z'$-portal is one of most popular and well-explored scenarios of dark matter (DM). To avoid the strong constraints coming from dilepton resonance searches at the LHC and direct detection of DM, it is usually required that in addition to being leptophobic, the $Z'$ is axially coupled to either the (fermionic) DM or the standard model (SM) quarks. The first possibility has been extensively studied both in the context of simplified model and UV complete scenarios. However, the studies on the second possibiliy are largely confined to simplified models only. Here, we construct the minimal UV completion of these models satisfying both the criteria of leptophobia and purely axial $Z'-$quark coupling. The anomaly cancellation conditions demand highly non-trivial structures, not only in the dark sector, but also in the Higgs sector.

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arXiv2020

The "96 GeV excess'' at the ILC

The CMS collaboration reported an intriguing \sim 3 sigma (local) excess at 96 GeV in the light Higgs-boson search in the diphoton decay mode. This mass coincides with a \sim 2 sigma (local) excess in the bb final state at LEP. We present the interpretation of this possible signal as the lightest Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). It is shown that the type II and type IV (flipped) of the N2HDM can perfectly accommodate both excesses simultaneously, while being in agreement with all experimental and theoretical constraints. The excesses are most easily accommodated in the type II N2HDM, which resembles the Yukawa structure of supersymmetric models. We discuss the experimental prospects for constraining our explanation at future $e^+e^-$ colliders, with concrete analyses based on the ILC prospects.

hep-ph↗

arXiv2019

The "96 GeV excess" in the N2HDM

The CMS collaboration reported an intriguing $\sim 3 \, σ$ (local) excess at $96\;$GeV in the light Higgs-boson search in the diphoton decay mode. This mass coincides with a $\sim 2 \, σ$ (local) excess in the $b\bar b$ final state at LEP. We present the interpretation of this possible signal as the lightest Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). We show that the type II and type IV (flipped) of the N2HDM can perfectly accommodate both excesses simultaneously, while being in agreement with all experimental and theoretical constraints. The excesses are most easily accommodated in the type II N2HDM, which resembles the Yukawa structure of supersymmetric models. We discuss the experimental prospects for constraining our explanation via charged Higgs-boson decays at the LHC or direct production of the $\sim 96\,$GeV Higgs boson at a future lepton collider like the ILC.

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arXiv2019

An N2HDM Solution for the possible 96 GeV Excess

We discuss a ~3 sigma signal (local) in the light Higgs-boson search in the diphoton decay mode at ~96 GeV as reported by CMS, together with a ~2 sigma excess (local) in the bb final state at LEP in the same mass range. We review the interpretation of this possible signal as a Higgs boson in the 2~Higgs Doublet Model with an additional real Higgs singlet (N2HDM). It is shown that the lightest Higgs boson of the N2HDM can perfectly fit both excesses simultaneously, while the full Higgs-boson sector is in agreement with all Higgs-boson measurements and exclusion bounds as well as other theoretical and experimental constraints. It is demonstrated that in particular the N2HDM type~II and can fit the data best, leading to a supersymmetric interpretation. The NMSSM and the munuSSM are briefly reviewed in this respect.

hep-ph↗

arXiv2019

A 96 GeV Higgs Boson in the N2HDM

We discuss a $\sim 3\,σ$ signal (local) in the light Higgs-boson search in the diphoton decay mode at $\sim 96$ GeV as reported by CMS, together with a $\sim 2\,σ$ excess (local) in the $b \bar b$ final state at LEP in the same mass range. We interpret this possible signal as a Higgs boson in the 2 Higgs Doublet Model with an additional real Higgs singlet (N2HDM). We find that the lightest Higgs boson of the N2HDM can perfectly fit both excesses simultaneously, while the second lightest state is in full agreement with the Higgs-boson measurements at 125 GeV, and the full Higgs-boson sector is in agreement with all Higgs exclusion bounds from LEP, the Tevatron and the LHC as well as other theoretical and experimental constraints. We show that only the N2HDM type II and IV can fit both the LEP excess and the CMS excess with a large ggF production component at $\sim 96$ GeV. We derive bounds on the N2HDM Higgs sector from a fit to both excesses and describe how this signal can be further analyzed at the LHC and at future $e^+e^-$ colliders, such as the ILC.

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