arXiv subjects

Jayita Lahiri

Publications and source records attributed to Jayita Lahiri.

At least 19 recordsLinked to original sources

arXiv2026

Search for Dark Matter in 2HDMS at LHC and future Lepton Colliders

We investigate the phenomenological prospects of the Two Higgs Doublet and Complex Singlet Scalar Extension (2HDMS) in the context of dark matter (DM) and Higgs phenomenology. The 2HDMS provides an enlarged Higgs sector along with a DM candidate. In this work, we perform an exhaustive scan to find representative benchmarks which are consistent with all theoretical and experimental constraints. We choose benchmarks with light, intermediate and massive DM masses and in some cases, also accommodate the 95 GeV excess in $b\bar{b}$ and $γγ$ channels observed at the Large Electron-Positron Collider (LEP) and Large Hadron Collider (LHC). We focus on the relevant signatures at the LHC and at proposed future lepton colliders including electron-positron and muon colliders. Using a cut and count analysis, we show that while the High Luminosity LHC (HL-LHC) may give a hint of new physics, future lepton colliders prove to be efficient discovery probes for the 2HDMS.

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arXiv2026

CP-violation and its implications in a complex singlet extension of 2HDM

We investigate CP-violation in the complex singlet extension of the general Two Higgs Doublet Model (2HDM) with Yukawa alignment condition. We first explore the possibility of explicit CP-violation in the extended scalar sector while the 125 GeV Higgs remains exactly Standard Model (SM)-like. We identify an additional source of CP violation in the complex singlet extension compared to the 2HDM, which allows this model a substantially greater freedom in satisfying the stringent EDM constraints. We also incorporate dark matter in this model and investigate the impacts of constraints from the dark sector on the model parameter space and its interplay with CP-violation phases. We further explore the possibility of detecting such a scenario at future collider experiments via CP-violating trilinear couplings among the non-standard scalars. Finally, we also deviate from the exact alignment limit and investigate the CP-properties of the observed Higgs boson in the context of our model. We demonstrate the strong model-dependent nature of the detection prospects of the CP-phase of the Higgs boson at future experiments, exploring both fermion couplings as well as the trilinear self-coupling of the Higgs boson.

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arXiv2025

Constraining the Inert Doublet Model at the LHC

In this work, we analyze experimental exclusion bounds that have been derived within a specific new physics realization, the two Higgs-doublet model with a pseudoscalar singlet (2HDMa), and their application to a different model, the Inert Doublet Model (IDM), that features the same final state. In this context, we discuss the sensitivity of the ATLAS search for the 2HDMa in final states with leptons and missing energy. We demonstrate that, with cuts optimized for a specific model topology, other new physics scenarios with larger rates might yet escape detection. We also give an update on constraints from vector boson fusion production of the Standard Model-like scalar and subsequent invisible decay from full Run 2 data on the parameter space of the IDM, with a special emphasis on the off-shell region, as well as a search that specifically concentrates on soft lepton final states.

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arXiv2025

The Influence of Lepton Portal on the WIMP-pFIMP framework

The dynamics and detection possibility of a pseudo-FIMP (pFIMP) dark matter (DM) in the presence of a thermal DM have been studied in different contexts. The pFIMP phenomenology largely depends on the WIMP-like partner DM, as pFIMP interacts with the standard model (SM) particles only via the partner DM loop. Introducing a lepton portal interaction, which connects DM directly to the SM lepton sector, improves its detection prospects. However, such possibilities are constrained strongly by the non-observation of lepton flavor-violating decays. Interestingly, this also makes it possible to probe such models in future low-energy experiments. In this article, we have tried to establish such connections and find parameter space which respects the limits from DM relic, direct, indirect, and lepton flavor violation (LFV). We also recast the constraints from di-lepton/di-tau plus missing energy signal at the LHC on our model and provide projections for HL-LHC and future lepton colliders. Although the LFV and collider limits mainly concern WIMPs, the parameter space for pFIMPs is also constrained due to its strong connection to WIMPs through DM relic density and detection prospects.

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arXiv2025

Optimal sensitivity of anomalous charged triple gauge couplings through $W$ boson helicity at the $e^+e^-$ colliders

We study the estimation of anomalous charged triple gauge couplings (cTGCs) parameterized in a model-independent Standard Model effective field theory (SMEFT) framework via $WW$ production followed by semi-leptonic decay at the $e^+e^-$ colliders. The anomalous $(WWV~(V=γ,Z))$ couplings are given in terms of Wilson coefficients of three CP-conserving and two CP-violating dimension-6 operators in the HISZ basis. We adopt the optimal observable technique (OOT) to extract the sensitivity of these anomalous couplings and compare it with the latest experimental limits on anomalous couplings studied at the LHC. The limits on the anomalous couplings obtained via OOT are significantly tighter than the ones obtained using standard $χ^2$ analysis. The impact of different helicity combinations of the $W$ boson pair in determining optimal sensitivity is analyzed. The constraints on CP-violating operators from the electron electric dipole moment (EDM) are also discussed.

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arXiv2025

Reinterpretation and preservation of data and analyses in HEP

Data from particle physics experiments are unique and are often the result of a very large investment of resources. Given the potential scientific impact of these data, which goes far beyond the immediate priorities of the experimental collaborations that obtain them, it is imperative that the collaborations and the wider particle physics community publish and preserve sufficient information to ensure that this impact can be realised, now and into the future. The information to be published and preserved includes the algorithms, statistical information, simulations and the recorded data. This publication and preservation requires significant resources, and should be a strategic priority with commensurate planning and resource allocation from the earliest stages of future facilities and experiments.

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arXiv2025

Optimal New Physics estimation in presence of Standard Model backgrounds

In this work, we develop a numerical technique for the optimal estimation of the new physics (NP) couplings applicable to any collider process without any simplifying assumptions. This approach also provides a way to measure the quality of the NP estimates derived using standard $χ^2$ analysis and can be used to gauge the advantages of various modalities of collider design. We illustrate the techniques and arguments by considering the pair production of heavy charged fermions at an $e^+e^-$ collider.

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arXiv2024

Dark Matter Phenomenology in 2HDMS in light of the 95 GeV excess

The Two Higgs Doublet model extended with a complex scalar singlet (2HDMS) is a well-motivated Beyond Standard Model candidate addressing several open problems of nature. In this work, we focus on the dark matter (DM) phenomenology of the complex scalar singlet where the real part of the complex scalar obtains a vacuum expectation value. The model is characterized by an enlarged Higgs spectrum comprising six physical Higgs bosons and a pseudoscalar DM candidate. We address the impact of accommodating the 95 GeV excess on the 2HDMS parameter space and DM observables after including all theoretical and experimental constraints. Finally, we look into the prospects of this scenario at HL-LHC and future lepton colliders for a representative benchmark.

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arXiv2024

Vacuum (in)stability in 2HDMS vs N2HDM

In this work, we examine the criteria for vacuum stability in two models with extended scalar sectors namely, the N2HDM and the 2HDMS and make a detailed comparison between the two. For the purpose of demonstration, we choose a scenario which can accommodate the recently observed 95 GeV excess in both models. We further explore the impact of the measurement of the Yukawa couplings, the gauge boson couplings and most importantly the trilinear self-couplings of the scalars, in distinguishing the vacuum structure in both models. We further investigate the constraints from vacuum stability on the 2HDMS scenario that accommodates a viable dark matter candidate and compare it with the N2HDM case.

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arXiv2024

Coscattering in the Extended Singlet-Scalar Higgs Portal

We study the coscattering mechanism in a simple Higgs portal which add two real singlet scalars to the Standard Model. In this scenario, the lighter scalar is stabilized by a single $\mathcal{Z}_2$ symmetry and acts as the dark matter relic, whose freeze-out is driven by conversion processes. The heavier scalar becomes an unstable state which participate actively in the coscattering. We find viable parameter regions fulfilling the measured relic abundance, while evading direct detection and big-bang nucleosynthesis bounds. In addition, we discuss collider prospects for the heavier scalar as a long-lived particle at present and future detectors.

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arXiv2023

Two-component dark matter : How to get the hint at collider?

We investigate ways of identifying two kinds of dark matter (DM) component particles at high-energy colliders. The strategy is to notice and distinguish double-peaks(humps) in the missing energy/transverse energy distribution. The relative advantage of looking for {\em missing energy} is pointed out, in view of the fact that the longitudinal component of the momentum imbalance becomes an added input. It thus turns out that an electron-positron collider is better suited for discovering a two-component DM scenario. Furthermore, using Gaussian fits of the distribution histograms, we develop a set of criteria to evaluate the distinguishability of the two-peaks quantitatively.

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arXiv2023

Mono-X signal and two component dark matter: new distinction criteria

The identification and isolation of two WIMP dark matter (DM) components at colliders is of wide interest on the one hand but extremely challenging on the other, especially when the dominant signal of both DM components is of the mono-X type ($X=γ, Z, H$). After emphasizing that an $e^+e^-$ collider is more suitable for this goal, we first identify the theoretical principles that govern the occurrence of two peaks in missing energy (ME) distribution, in a double-DM scenario. We then identify a variable that rather spectacularly elicits the double-peaking behaviour, namely, the plot of bin-wise statistical significance ($S/\sqrt{B}$) against ME. Using Gaussian fits of the histograms, we apply a set of criteria developed by us, to illustrate the above points numerically for suitable benchmarks.

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arXiv2023

Dynamics of the pseudo-FIMP in presence of a thermal Dark Matter

We demonstrate that in a two component dark matter (DM) set up, when DM$_1$ is equilibrated with the thermal bath, the other DM$_2$, in spite of having feeble or negligible interaction with the SM particles, can be brought to equilibrium just by having sizeable interaction with DM$_1$. We propose that such DM candidates (DM$_2$) should be classified into a category called pseudo-FIMP (pFIMP) having unique freeze-out characteristics which depend on the thermal DM partner. The draft elaborates upon the pFIMP properties from a generic coupled Boltzmann Equations (cBEQ) in a model independent way, followed by a concrete model illustration.

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arXiv2023

Dark matter phenomenology in Z'2 broken singlet extended 2HDM

Many different approaches have been made to explain the nature of dark matter (DM), but it remains and unsolved mystery of our universe. In this work we examine a type II two-Higgs-doublet model extended by a complex singlet (2HDMS), where the pseudo-scalar component of the singlet acts as a natural DM candidate. The DM candidate is stabilized by a Z'2 symmetry, which is broken spontaneously by the singlet acquiring a vacuum expectation value (vev). This vev in turn causes the scalar component of the singlet to mix with the scalar components of the two doublets, which results in three scalar Higgs particles. Additionally we aim to include an excess around 95 GeV, which was observed at CSM and LEP and can be explained by one of the three scalar Higgs particles. After introducing the model, we apply experimental and theoretical constraints and find a viable benchmark point. We then look into the DM phenomenology as well as collider phenomenology.

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arXiv2023

High scale validity of two Higgs doublet scenarios with a real scalar singlet dark matter

We study the high-scale validity of two kinds of two Higgs doublet models (2HDM), namely, Type-II and Type-X, but with a scalar SU(2) singlet dark matter (DM) candidate in addition in each case. The additional quartic couplings involving the DM particle in the scalar potential in both the scenarios bring in additional constraints from the requirement of perturbative unitarity and vacuum stability. DM relic density and direct search constraints play a crucial role in this analysis as the perturbative unitarity of the DM-Higgs portal couplings primarily decide the high scale validity of the model. We find that, within the parameter regions thus restricted, the Type-II scenario must have a cut-off at around $10^6$ GeV, while the Type-X scenario admits of validity upto the Planck scale. However, only those regions which are valid upto about $10^8$ GeV in Type-X 2HDM is amenable to detection at the High-luminosity LHC (upto 3000 $fb^{-1}$), while most of the parameter space of the Type-II scenario mentioned above is likely to be detectable.

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arXiv2023

Probing anomalous $Z\,Z\,γ$ and $Z\,γ\,γ$ Couplings at the $e^+\,e^-$ Colliders using Optimal Observable Technique

We study the anomalous $ZZγ$ and $Zγγ$ couplings that can be probed via $Zγ$ production at the $e^+ \, e^-$ colliders. We take Standard Model Effective Field Theory (SMEFT) approach to examine these anomalous neutral triple gauge couplings in a model independent way. There are four independent dimension-8 operators that generate these gauge interactions, one of them is CP-conserving and rest three are CP-violating. We adopt optimal observable technique to extract the sensitivity at which these anomalous couplings can be probed at future $e^+e^-$ colliders and then compare the results with the latest experimental limit obtained at the LHC. We also study the impact and advantage of beam polarization in these precision measurements. Statistical limit (95\% C.L.) on individual anomalous couplings as well as the correlation between various couplings have been discussed in detail.

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arXiv2022

Detection possibility of a Pseudo-FIMP in presence of a thermal WIMP

A dark matter (DM) having feeble interaction with the visible sector can thermalise via substantial interaction with a Weakly Interacting Massive Particle (WIMP). Such DM candidates are categorised as pseudo-FIMP (pFIMP). pFIMP can provide both direct and indirect search prospects via WIMP loop. This work focuses into such possibilities. We provide all such one loop graphs involving scalar, fermion and vector boson particles via which pFIMP can interact with the Standard Model assuming both of them are stabilised via $\mathbb{Z}_2\otimes \mathbb{Z}_2^{\prime}$ symmetries. We elaborate upon a model where a fermion DM acts as WIMP and a scalar singlet acts as pFIMP having negligible Higgs portal interaction and substantial conversion via Yukawa interaction. We study in details the loop induced direct and indirect search prospects of the pFIMP in the relic density allowed region of the model.

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arXiv2022

Distinguishing two dark matter component particles at $e^+e^-$ colliders

In this work we demonstrate that a distorted double hump like missing energy ($\slashed{E}$) or missing transverse momentum ($\slashed{E}_T$) or missing mass ($\slashed{M}$) distribution at $e^+e^-$ colliders may hint towards the presence of multipartite dark sector. We illustrate the phenomena using a two component dark matter (DM) model involving an inert scalar doublet stabilised under a $\mathcal{Z}_2$ symmetry providing a scalar DM, one vector like fermion doublet and a right handed fermion singlet both stabilised under a different $\mathcal{Z}^{'}_2$ providing a fermion DM. We indicate the region of parameter space where the production of the heavy charged particles and their subsequent decay to DM yield double peak behaviour in $\slashed{E}$ spectrum after satisfying DM constraints. Importantly, we illustrate why and how $\slashed{E}$ serves as a better variable than $\slashed{E}_T$ in distinguishing two component DM frameworks and therefore how International Linear Collider (ILC) does better than the ongoing Large Hadron Collider (LHC). We also chalk out a set of criteria to identify and segregate the second peak in $\slashed{E}$ spectrum, after a careful analysis of the corresponding Standard Model (SM) background contribution, which plays a crucial role.

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