arXiv subjects

Priyotosh Bandyopadhyay

Publications and source records attributed to Priyotosh Bandyopadhyay.

At least 55 records · Page 3Linked to original sources

arXiv2016

Extended Higgs sectors in the context of supersymmetry at the LHC

We studied the extension of Standard Model (SM) Higgs sector with $SU(2)$ triplet and SM gauge singlet in the context of supersymmetry. For a $Z_3$ symmetric superpotential where the singlet field generates the bi-linear Higgs mixing term between two Higgs doublets dynamically. Models like this often have a very light pseudoscalar as pseudo-Nambu Goldstone model of an extra $U(1)$ symmetry. We investigate the possibility of such light hidden Higgs boson with the data of the discovered Higgs boson around 125 GeV. Along with the neutral sector, the charged Higgs bosons in the triplet extended case are really interesting as the triplet charged Higgs bosons give rise to new decay mode to $Z W^\pm$ along with $ a_1 W^\pm$ due to the existence of light pseudoscalar. These new modes can be looked for at the LHC in the search for the Higgs bosons in other representations of $SU(2)$.

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arXiv2016

General Analysis of the Charged Higgs Sector of the $Y=0$ Triplet-Singlet Extension of the MSSM at the LHC

We investigate the extended Higgs sectors, specially the charged Higgs sector in a supersymmetric $Y=0$ $SU(2)$ triplet and a Standard Model (SM) gauge singlet extension of SM. We show that in this model the allowed data for the Higgs boson interaction eigenstates tend to group into separate blocks for $SU(2)$ triplet, doublet and singlet. The triplet sector has two degenerate paired states, each pair composed of a mostly-triplet charged Higgs and of a mostly-triplet scalar or pseudoscalar state. The mostly-doublet sector involves a Standard Model like Higgs of 125 GeV and extra mass-degenerate states, composed of a charged, a scalar and a pseudoscalar. The CP-odd component of the singlet scalar, after supersymmetry breaking, takes the role of a pseudo-Nambu-Goldstone mode in the $Z_3$ symmetric case, while the CP-even one becomes decoupled. In a second part of our study we investigate the different decay processes allowed to a charged Higgs boson of this model. Specifically, we search for general signatures of the TNMSSM in order to distinguish among Higgs fields belonging to $SU(2)$ doublet, triplet and singlet representations at the LHC. We also propose few golden plated final state modes carrying the distinctive signatures of this model which could be investigated in collider searches. We also show how in the decoupling limit of the triplet ($|λ_T| \simeq 0$) affects the decays as well as the production channels at the LHC.

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arXiv2016

Bounds on the Conformal Scale of a Minimally Coupled Dilaton and Multi-Leptonic Signatures at the LHC

We explore the potential for the discovery of a dilaton $\mathcal{O}(200-500)$ GeV in a classical scale/conformal invariant extension of the Standard Model by investigating the size of the corresponding breaking scale $Λ$ at the LHC, extending a previous analysis. In particular, we address the recent bounds on $Λ$ derived from Higgs boson searches. We investigate if such a dilaton can be produced via gluon-gluon fusion, presenting rates for its decay either into a pair of Higgs bosons or into two heavy gauge bosons, which can give rise to multi-leptonic final states. A detailed analysis via PYTHIA-FastJet has been carried out of the dominant Standard Model backgrounds, at a centre of mass energy of 14 TeV. We show that early data of $\sim 20$ fb$^{-1}$ can certainly probe the region of parameter space where such a dilaton is allowed. A conformal scale of 5 TeV is allowed by the current data, for almost all values of the dilaton mass investigated.

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arXiv2016

Non-standard charged Higgs decay at the LHC in Next-to-Minimal Supersymmetric Standard Model

We consider next-to-minimal supersymmetric standard model (NMSSM) which has a gauge singlet superfield. In the scale invariant superpotential we do not have the mass terms and the whole Lagrangian has an additional $Z_3$ symmetry. This model can have light scalar and/or pseudoscalar allowed by the recent data from LHC and the old data from LEP. We investigate the situation where a relatively light charged Higgs can decay to such singlet-like pseudoscalar and a $W^\pm$ boson giving rise to final state containing $τ$ and/or $b$-jets and lepton(s). Such decay evades the recent bounds on charged Higgs from the LHC. According to our PYTHIA-FastJet based simulation such a scenario can be probed with early data of 10 fb$^{-1}$ at the LHC center of mass energy of 13 and 14 TeV.

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arXiv2016

Higgs bosons: discovered and hidden, in extended Supersymmetric Standard Models at the LHC

We investigate an extension of the Minimal Supersymmetric Standard Model (MSSM) containing a $SU(2)$ Higgs triplet of zero hypercharge and a gauge singlet. We focus on a scenario of this model which allows a light pseudoscalar and/or a scalar below $100$ GeV in the spectrum, consistent with the most recent data from the LHC and the earlier data from the LEP experiments. We analyze the exotic decay of the discovered Higgs $(h_{125})$ into two light (hidden) Higgs bosons present in the extension. The latter are allowed by the uncertainties in the Higgs decay $h_{125}\to WW^*$, $h_{125}\to ZZ^*$ and $h_{125}\to γγ$. We have searched for such light Higgs bosons in the $2b+2τ$, $\geq 3τ$, $2b+2μ$ and $2τ+2μ$ final states at the LHC with 13 and 14 TeV. A region of such parameter space can be explored with an integrated luminosity of 25 fb$^{-1}$ at the LHC.

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arXiv2015

Lepton flavour violating signature in supersymmetric $U(1)^\prime$ seesaw models at the LHC

We consider a $U(1)'$ supersymmetric seesaw model in which a right-handed sneutrino is a thermal dark matter candidate whose relic density can be in the right range due to its coupling to relatively light $\tilde{Z'}$, the superpartner of the extra gauge boson $Z'$. Such light $\tilde Z'$ can be produced at the LHC through cascade decays of colored superparticles, in particular, stops and sbottoms, and then decay to a right-handed neutrino and a sneutrino dark matter, which leads to lepton flavor violating signals of same/opposite-sign dileptons (or multileptons) accompanied by large missing energy. Taking some benchmark points, we analyze the opposite- and same-sign dilepton signatures and the corresponding flavour difference i.e., ($2e-2μ$). It is shown that $5σ$ signal significance can be reached for some benchmark points with very early data of $\sim 2$ fb$^{-1}$ integrated luminosity. In addition, $3\ell$ and $4\ell$ signatures also look promising to check the consistency in the model prediction, and it is possible to reconstruct the $\tilde{Z'}$ mass from $jj\ell$ invariant mass distribution.

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arXiv2015

Probing the Hidden Higgs Bosons of the $Y=0$ Triplet- and Singlet-Extended Supersymmetric Standard Model at the LHC

We investigate the scalar sector in an extension of the Minimal Supersymmetric Standard Model (MSSM) containing a $SU(2)$ Higgs triplet of zero hypercharge and a gauge singlet beside the $SU(2)$ scalar doublets. In particular, we focus on a scenario of this model which allows a light pseudoscalar and/or a scalar below $100$ GeV, consistent with the most recent data from the LHC and the earlier data from the LEP experiments. We analyze the exotic decay of the discovered Higgs $(h_{125})$ into two light (hidden) Higgs bosons present in the extension. The latter are allowed by the uncertainties in the Higgs decay $h_{125}\to WW^*$, $h_{125}\to ZZ^*$ and $h_{125}\to γγ$. The study of the parameter space for such additional scalars/pseudoscalars decay of the Higgs is performed in the gluon fusion channel. The extra hidden Higgs bosons of the enlarged scalar sector, if they exist, will then decay into lighter fermion paris, i.e., $b\bar{b}$, $τ\barτ$ and $μ\barμ$ via the mixing with the doublets. A detailed simulation using PYTHIA of the $2b+2τ$, $\geq 3τ$, $2b+2μ$ and $2τ+2μ$ final states is presented. From our analysis we conclude that, depending on the selected benchmark points, such decay modes can be explored with an integrated luminosity of 25 fb$^{-1}$ at the LHC at a center of mass energy of 13 TeV.

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arXiv2015

Perspectives on a Supersymmetric Extension of the Standard Model with a $Y=0$ Higgs Triplet and a Singlet at the LHC

We investigate a supersymmetric extension of the Minimal Supersymmetric Standard Model (MSSM), called the TNMSSM, containing a $SU(2)$ Higgs triplet $(\hat{T})$ of $Y=0$ hypercharge and a singlet superfields $(\hat{S})$ in the corresponding superpotential. The model can be viewed, equivalently, as an extension of the NMSSM with the addition of a $\hat{T}-\hat{S}$ interaction and of an extra coupling of the triplet to the two Higgs doublets of the NMSSM. In this scenario the Higgs particle spectrum at tree-level gets additional mass contributions from the triplet and singlet scalar components respect to the MSSM, which are particularly enhanced at low $\tanβ$. We calculate the one-loop Higgs masses for the neutral physical Higgs bosons by a Coleman-Weinberg effective potential approach. In particular, we investigate separately the impact of the radiative corrections due to the electroweak, gauge-gaugino-higgsino, fermion-sfermion and Higgs self-interactions to the Higgs masses. Due to the larger number of scalars and of triplet and singlet couplings, the Higgs corrections can be larger than the strong corrections. This reduces the amount of fine-tuning required to fit the recent Higgs data. Using the expressions of the beta-functions of the model, we show that the large triplet singlet coupling remains perturbative up to $\sim10^{8-10}$ GeV. The model is also characterized by a light pseudoscalar in the spectrum, which is a linear combination of the triplet, doublet and singlet CP-odd components. We discuss the production and decay signatures of the Higgs bosons in this model, including scenarios with hidden Higgses, which could be investigated at the LHC in the current run.

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arXiv2014

Multi-Lepton Signatures of the Triplet Like Charged Higgs at the LHC

We study multi-lepton signatures of the triplet like charged Higgs at the LHC in the context of $Y=0$ triplet extended supersymmetric model (TESSM). In TESSM the $h_i^\pm W^\mp Z$ coupling appears at tree level when the triplet vacuum expectation value is nonzero, and because of the coupling the charged Higgs decay channels as well as the production channels can dramatically change at the LHC. We show that for the triplet dominated charged Higgs the main production channels are no longer through the top decay or $gg$ and $gb$ fusions since these are very suppressed due to the lack of triplet-SM fermion coupling. In the numerical analysis, we consider also other possible production channels some of which have additional contributions from the diagrams containing $h_i^\pm W^\mp Z$ vertex. We investigate the decay channels of a triplet like light charged Higgs ($m_{h_1^{\pm}}\leq 200$ GeV) and show that depending on the triplet component, the charged Higgs can substantially decay to $W^\pm Z$. We further examine the $3l$, $4l$, $5l$ multi-lepton signatures of the triplet like charged Higgs by considering four different benchmark points for which we perform PYTHIA level simulation using FastJet for jet formation at the LHC with 14 TeV. We found that for favorable parameters the earliest discovery with 5$σ$ signal significance can appear with early data of 72 fb$^{-1}$ of integrated luminosity. We also present the invariant mass distribution $M_{lljj}$ for ($\geq 3\ell)+(\ptmiss \geq 30$ GeV) and $(\geq 3\ell)+(\geq 2j)+(\ptmiss \geq 30$ GeV) and show that in addition to the charged Higgs mass peak, an edge that carries information about heavy intermediate neutral Higgs bosons arises at the end of the mass distribution.

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arXiv2014

Triplet Extended MSSM: Fine Tuning vs Perturbativity and Experiment

In this study we investigate the phenomenological viability of the $Y=0$ Triplet Extended Supersymmetric Standard Model (TESSM) by comparing its predictions with the current Higgs data from ATLAS, CMS, and Tevatron, as well as the measured value of the $B_s\to X_s γ$ branching ratio. We scan numerically the parameter space for data points generating the measured particle mass spectrum and also satisfying current direct search constraints on new particles. We require all the couplings to be perturbative up to the scale $Λ_{\rm UV}=10^4$ TeV, by running them with newly calculated two loop beta functions, and find that TESSM retains perturbativity as long as $λ$, the triplet coupling to the two Higgs doublets, is smaller than 1.34 in absolute value. For $|λ|\gtrsim 0.8$ we show that the fine-tuning associated to each viable data point can be greatly reduced as compared to values attainable in MSSM. Finally, we perform a fit by taking into account 58 Higgs physics observables along with $\mathcal{B}r(B_s\to X_s γ)$, for which we calculate the NLO prediction within TESSM. We find that, although naturality prefers a large $|λ|$, the experimental data disfavors it compared to the small $|λ|$ region, because of the low energy observable $\mathcal{B}r(B_s\to X_s γ)$.

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arXiv2014

Higgs(es) in triplet extended supersymmetric standard model at the LHC

The recent discovery of the $\sim 125$ GeV Higgs boson by Atlas and CMS experiments has set strong constraints on parameter space of the minimal supersymmetric model (MSSM). However these constraints can be weakened by enlarging the Higgs sector by adding a triplet chiral superfield. In particular, we focus on the $Y=0$ triplet extension of MSSM, known as TESSM, where the electroweak contributions to the lightest Higgs mass are also important and comparable with the strong contributions. We discuss this in the context of the observed Higgs like particle around 125 GeV and also look into the status of other Higgs bosons in the model. We calculate the Br($B_s \to X_s γ$) in this model where three physical charged Higgs bosons and three charginos contribute. We show that the doublet-triplet mixing in charged Higgses plays an important role in constraining the parameter space. In this context we also discuss the phenomenology of light charged Higgs probing $H^\pm_1-W^\mp-Z$ coupling at the LHC.

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arXiv2014

Naturality vs perturbativity, $B_s$ physics, and LHC data in triplet extension of MSSM

In this study we investigate the phenomenological viability of the $Y=0$ Triplet Extended Supersymmetric Standard Model (TESSM) by comparing its predictions with the current Higgs data from ATLAS, CMS, and Tevatron, as well as the measured value of the $B_s\to X_s γ$ branching ratio. We scan numerically the parameter space for data points generating the measured particle mass spectrum and also satisfying current direct search constraints on new particles. We require all the couplings to be perturbative up to the scale $Λ_{\rm UV}=10^4$ TeV, by running them with newly calculated two loop beta functions, and find that TESSM retains perturbativity as long as $λ$, the triplet coupling to the two Higgs doublets, is smaller than 1.34 in absolute value. For $|λ|\gtrsim 0.8$ we show that the fine-tuning associated to each viable data point can be greatly reduced as compared to values attainable in MSSM. We also find that for perturbatively viable data points it is possible to obtain either enhancement or suppression in $h\rightarrow γγ$ decay rate depending mostly on the relative sign between $M_2$ and $μ_D$. Finally, we perform a fit by taking into account 58 Higgs physics observables along with $\mathcal{B}r(B_s\to X_s γ)$, for which we calculate the NLO prediction within TESSM. We find that, although naturality prefers a large $|λ|$, the experimental data disfavors it compared to the small $|λ|$ region, because of the low energy observable $\mathcal{B}r(B_s\to X_s γ)$. We notice, though, that this situation might change with the second run of LHC at 14 TeV, in case the ATLAS or CMS results confirm, with smaller uncertainty, a large enhancement in the Higgs decay channel to diphoton, given that this scenario strongly favours a large value of $|λ|$.

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arXiv2013

Production of two Higgses at the Large Hadron Collider in CP-violating MSSM

Production of two Higgs bosons is studied in a CP violating supersymmetric scenario at the Large Hadron Collider with $E_{cm}=14$ TeV. There exists a region where a very light Higgs $\lesssim 50$ GeV could not be probed by LEP experiment. This leads to so called 'LEP hole' region. Recently LHC found a Higgs boson around $\sim 125$ GeV, which severely constrains the possibility of having lighter Higgs bosons, which cannot be detected, i.e., buried Higgs, in this model. We investigate the possibility of buried Higgs bosons along with the direct and indirect bounds coming from LEP, LHC and other experiments. In particular we take into account the constraints from EDM and from $B$-observables. We analyse first the case where a Higgs boson mass is around 125 GeV and the other two Higgs masses are below 100 GeV and not observabed so far. In the second case the lightest Higgs boson mass is around 125 GeV and the other two are decoupled. We analyse the production of two Higgses and their decay modes leading to various final states for these benchmark points. We perform a collider simulation with PYTHIA and Fastjet where we consider all the major backgrounds. Among the final states we have analysed, we find that $2b+2τ$ is promising and the signal significance is $5σ$ at an integrated luminosity $\lesssim 10$ fb$^{-1}$. For some benchmark points it is also possible to observe the light Higgs mass peak. We also explore the leptonic final state which could be instrumental in the precision measurement of a very light Higgs.

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arXiv2013

Status of $Y=0$ Triplet Higgs with supersymmetry in the light of $\sim 125$ GeV Higgs discovery

We study the $Y=0$ triplet extended supersymmetric model in the light of the recent Higgs boson discovery. We calculate full one loop Higgs mass spectrum in this model where the possible doublet-triplet mixing is considered in the charged Higgs sector. This mixing changes the prediction of $\mathcal{B}r(B_s\to X_s γ)$ in this model, compared to the MSSM. The constraints from the $\sim 125$ GeV Higgs along with $\mathcal{B}r(B_s\to X_s γ)$ are incorporated to find out the allowed parameter space. The lower bounds on the third generation squark masses coming from 125 GeV Higgs are rather week in this scenario compared to most constrained supersymmetric scenarios, e.g. a 200 GeV squark mass is still possible.

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arXiv2012

Higgs Signatures in Inverse Seesaw Model at the LHC

In the inverse seesaw mechanism where the spontaneously broken B-L symmetry induces tiny B-L violating Majorana masses for right-handed neutrinos, non-standard Higgs signatures can arise due to a possible Higgs doublet and singlet mixing and/or Higgs boson decays to a left- and right-handed neutrino. This leads to a remarkable feature of hadronically quiet di-lepton final states which can exhibit, in particular, lepton flavour violating signatures coming from flavour-dependent neutrino Yukawa couplings. In this process, one lepton coming from the right-handed decay could be soft enough can be missed by the trigger level cuts of CMS and ATLAS for the di-lepton plus missing energy signature. The prospects of such a signature are investigated for 8 TeV and 14 TeV center of mass energy of the LHC, taking the maximum value of the allowed neutrino Yukawa coupling and the right-handed neutrino mass of 100 GeV. A PYTHIA level simulation shows that the integrated luminosity of 10--20/fb and 1.6/fb for 8 TeV is required to observe the inclusive leptonic and lepton flavour violating signatures, respectively. For 14 TeV, the reach is more and a larger parameter space of the inverse seesaw model can be probed.

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arXiv2011

Unusual Higgs boson signal in R-parity violating nonminimal supersymmetric models at the LHC

We predict an unconventional background free signal of the Higgs boson in $R$-parity violating nonminimal supersymmetric models at the Large Hadron Collider (LHC). The signal comprises dilepton plus four hadronic jets and two large displaced vertices. The displaced leptons and jets are coming from the decay of the lightest supersymmetric particle (LSP), which is predominantly a gauge-singlet neutrino. A pair of such LSPs can couple to a Higgs boson, created via gluon fusion. We have analyzed two cases - one corresponding to the tree-level Higgs boson mass and another with the one-loop corrected mass of the Higgs boson. A reliable Higgs mass reconstruction using this signal can lead to discovery at the LHC with center-of-mass energy $\sqrt{s}=14~\rm{TeV}$ and 5 fb$^{-1}$ of integrated luminosity $(\mathcal{L})$. Even at $\sqrt{s}=7~\rm{TeV}$ and $\mathcal{L}$ = 5 fb$^{-1}$, a reasonable number of events are expected. Besides, mass reconstruction of a gauge-singlet LSP can provide an estimate of the seesaw scale.

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arXiv2011

Probing Higgs in Type III Seesaw at the LHC

We show that the type III seesaw mechanism opens up a promising possibility of searching the Higgs boson in the $b \bar b$ channel through the Higgs production associated with a charged lepton coming from the decay of the triplet seesaw particle. In particular we look for the $2b$ signals with trileptons or same-sign dileptons to construct the Higgs and the triplet fermion mass and calculate the reach with the integrated luminosity of 10 fb$^{-1}$ at the 14 TeV LHC.

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arXiv2011

Higgs production in CP-violating supersymmetric cascade decays: probing the `open hole' at the Large Hadron Collider

A benchmark CP-violating supersymmetric scenario (known as 'CPX-scenario' in the literature) is studied in the context of the Large Hadron Collider (LHC). It is shown that the LHC, with low to moderate accumulated luminosity, will be able to probe the existing `hole' in the $m_{h_1}$-$\tanβ$ plane, which cannot be ruled out by the LEP data. We explore the parameter space with cascade decay of third generation squarks and gluino with CP-violating decay branching fractions. We propose a multi-channel analysis to probe this parameter space some of which are background free at an integrated luminosity of 5-10 fb$^{-1}$. Specially, multi-lepton final states ($3ł,\, 4ł$ and like sign di-lepton) are almost background free and have $5σ$ reach for the corresponding signals with very early data of LHC for both 14 TeV and 7 TeV center of mass energy.

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