We study CP violation (CPV) in the sneutrino sector within the B-L extension of the minimal supersymmetric Standard Model, wherein an inverse seesaw mechanism has been implemented. CPV arises from the new superpotential couplings in the (s)neutrino sector, which can be complex and the mixing of CP eigenstates induced by those couplings. CPV leads to asymmetries in so-called T-odd observables, but we argue that such asymmetries also lead to a wider distribution of those observables. We look at a final state where a sneutrino decays to a lepton, two jets, and missing transverse momentum at the Future Circular Collider operating in hadron-hadron mode at 100 TeV and with a luminosity of 3 ab-1. In order to exclude the CP conserving scenario we need to improve traditional analysis by introducing boosted decision trees using both standard kinematic variables and T-odd observables and we need Z′ boson not too much above current bounds as a portal to produce sneutrinos efficiently.

We study the generation of baryon asymmetry as well as dark matter (DM) in an extended reheating period after the end of slow-roll inflation. Within the regime of perturbative reheating, we consider different monomial potential of the inflaton field during reheating era. The inflaton condensate reheats the Universe by decaying into the Standard Model (SM) bath either via fermionic or bosonic decay modes. Assuming the leptogenesis route to baryogenesis in a canonical seesaw framework with three right handed neutrinos (RHN), we consider both the radiation bath and perturbative inflaton decay to produce such RHNs during the period of reheating when the maximum temperature of the SM bath is well above the reheating temperature. The DM, assumed to be a SM gauge singlet field, also gets produced from the bath during the reheating period via UV freeze-in. In addition to obtaining different parameter space for such nonthermal leptogenesis and DM for both bosonic and fermionic reheating modes and the type of monomial potential, we discuss the possibility of probing such scenarios via spectral shape of primordial gravitational waves.

This paper describes a method for detecting a rare top quark decay into a charm quark and a Higgs boson (H), which decays further into b quarks, at the large hadron collider (LHC), and introduces a tagging algorithm to identify boosted tops using large-R jets containing b- and c-tagged elements. We consider the associated production of the top quark with a W-boson and identify different observables to discriminate the signal from the Standard Model (SM) background events. Although our model with improved jet substructure methods outperforms existing approaches to tag such rare decay tops, the improvement in the New Physics reach in terms of t→cH branching ratio is marginal, even at the high luminosity run of LHC, compared to the existing limits from the LHC 13 TeV data. Although the result seems negative from the point of view of BSM reach, it is significant enough to motivate further studies in the search for the rare top decays at future colliders with higher energy and luminosity. Additionally, the paper utilizes SHAP, a game theory-based method, to analyze the contribution of each observable to the classification of events, offering valuable insights into the classifier. The approach presented in this paper is robust in scope and can be effectively implemented for similar probes of physics beyond the SM.

We study the boosted dark matter scenario in a two-component model. We consider a neutrinophilic two-Higgs doublet model, which consists of one extra Higgs doublet and a light right-handed neutrino. This model is extended with a light (∼10 MeV) singlet scalar dark matter (DM) φ3, which is stabilized under an extra dark Z2DM symmetry and can only effectively annihilate through the CP even scalar H. Although the presence of a light scalar H modifies the oblique parameters to put tight constraints on the model, the introduction of vectorlike leptons can potentially salvage the issue. The vectorlike doublet N and singlet χ are also stabilized through dark Z2DM symmetry. The lightest vectorlike mass eigenstate (χ1∼100 GeV) is the second DM component of the model. Individual scalar and fermionic DM candidates have Higgs/Z mediated annihilation, restricting the fermion DM in a narrow mass region while a somewhat broader mass region is allowed for the scalar DM. However, when two DM sectors are coupled, the annihilation channel χ1χ1→φ3φ3 opens up. As a result, the fermionic relic density decreases, and paves the way for a broader fermionic DM mass region with underabundant relic: a region of [30-65] GeV compared to a narrower [40-50] GeV window for the single component case. On the other hand, the light DM φ3 acquires significant boost from the annihilation of χ1, causing a dilution in the resonant annihilation of φ3. This in turn increases the scalar DM relic, allowing for a smaller mass region compared to the individual case. The exact and underabundant relic is achievable in a significant parameter space of the two-component model where the total DM relic is mainly dominated by the fermionic DM contribution. The scalar DM is found to be subdominant or equally dominant (∼30%–80% of total DM) with significant boost, which can be detected in experiments.

We propose an Unsupervised Learning Algorithm, Self-Organizing Maps (SOM), built on a neural network architecture, for the probe of a rare top decay, mediated by Flavor Changing Neutral Current (FCNC), to charm and the Higgs boson, with the Higgs boson further decaying to a pair of b-quarks or a pair of gauge bosons (W±/Z) in a boosted regime. Ideally, the particles originating from the decay of the boosted top lead to the reconstruction of a large-R jet, comprising three-prong substructures, with b- and c-tagged subjets. The SOM algorithm has been demonstrated as a model-agnostic anomaly-finder for probing the rare decay at the LHC, by mapping distinct signal and background regions to separate non-overlapping clusters on the Kohnen map. This helps to identify signal regions with higher signal significances. We also discuss the robustness of this algorithm, especially for other BSM probes with model-agnostic and model-dependent searches.

Interest in deep learning in collider physics has been growing in recent years, specifically in applying these methods in jet classification, anomaly detection, particle identification etc. Among those, jet classification using neural networks is one of the well-established areas. In this review, we discuss different tagging frameworks available to tag boosted objects, especially boosted Higgs boson and top quark, at the Large Hadron Collider (LHC). Our aim is to study the interplay of traditional jet substructure-based methods with the state-of-the-art machine learning ones. In this methodology, we would gain some interpretability of those machine learning methods, and which in turn helps to propose hybrid taggers relevant for tagging of those boosted objects belonging to both Standard Model (SM) and physics beyond the SM.

Top tagging has emerged as a fast-evolving subject due to the top quark’s significant role in probing physics beyond the standard model. For the reconstruction of top jets, machine learning models have shown a substantial improvement in the classification performance compared to the previous methods. In this work, we build top taggers using N-Subjettiness ratios and several energy correlation observables as input features to train the eXtreme Gradient BOOSTed decision tree (XGBOOST). The study finds that tighter parton-level matching leads to more accurate tagging. However, in real experimental data, where the parton-level data are unknown, this matching cannot be done. We train the XGBOOST models without performing this matching and show that this difference impacts the taggers’ effectiveness. Additionally, we test the tagger under different simulation conditions, including changes in centre-of-mass energy, parton distribution functions (PDFs), and pileup effects, demonstrating its robustness with performance deviations of less than 1%. Furthermore, we use the SHapley Additive exPlanation (SHAP) framework to calculate the importance of the features of the trained models. It helps us to estimate how much each feature of the data contributed to the model’s prediction and what regions are of more importance for each input variable. Finally, we combine all the tagger variables to form a hybrid tagger and interpret the results using the Shapley values.

We compare different jet-clustering algorithms in establishing fully hadronic final states stemming from the chain decay of a heavy Higgs state into a pair of the 125 GeV Higgs boson that decays into bottom-antibottom quark pairs. Such 4b events typically give rise to boosted topologies, wherein bb¯ pairs emerging from each 125 GeV Higgs boson tend to merge into a single, fat b-jet. Assuming large hadron collider (LHC) settings, we illustrate how both the efficiency of selecting the multi-jet final state and the ability to reconstruct from it the masses of all Higgs bosons depend on the choice of jet-clustering algorithm and its parameter settings. We indicate the optimal choice of clustering method for the purpose of establishing such a ubiquitous beyond the SM (BSM) signal, illustrated via a Type-II 2-Higgs Doublet Model (2HDM).

Boosted top quark tagging is one of the challenging, and at the same time exciting, tasks in high energy physics experiments, in particular in the exploration of new physics signals at the LHC. Several techniques have already been developed to tag a boosted top quark in its hadronic decay channel. Recently tagging the same in the semileptonic channel has begun to receive a lot of attention. In the current study, we develop a methodology to tag a boosted top quark (pT>200 GeV) in its semileptonic decay channel with a τ-lepton in the final state. In this analysis, the constituents of the top fatjet are reclustered using jet substructure technique to obtain the subjets, and then b- and τ- like subjets are identified by applying standard b- and τ-jet identification algorithms. We show that the dominant QCD background can be rejected effectively using several kinematic variables of these subjects, such as energy sharing among the jets, invariant mass, transverse mass, N-subjettiness etc., leading to high signal tagging efficiencies. We further assess possible improvements in the results by employing multivariate analysis techniques. We find that using this proposed top-tagger, a signal efficiency of ∼77% against a background efficiency of ∼3% can be achieved. We also extend the proposed top-tagger to the case of polarized top quarks by introducing a few additional observables calculated in the rest frame of the b-τ system. We comment on how the same methodology will be useful for tagging a boosted heavy BSM particle with a b and τ in the final state.

The detection of a single Higgs boson at the Large Hadron Collider (LHC) has allowed one to probe some properties of it, including the Yukawa and gauge couplings. However, in order to probe the Higgs potential, one has to rely on new production mechanisms, such as Higgs pair production. In this paper, we show that such a channel is also sensitive to the production and decay of a so-called 'flavon' field (HF), a new scalar state that arises in models that attempt to explain the hierarchy of the Standard Model (SM) fermion masses. Our analysis also focuses on the other decay channels involving the flavon particle, specifically the decay of the flavon to a pair of Z bosons (HF→ZZ) and the concurrent production of a top quark and charm quark via the φ→tc decays (φ=HF,AF), having one or more leptons in the final states. In particular, we show that, with 3000 fb-1 of accumulated data at 14 TeV (the Run 3 stage) of the LHC an heavy flavon HF with mass MHF≃2mt can be explored with 3σ-5σ significance through these channels.

The ultimate motivation of our study is to look for signs of physics beyond the Standard Model (BSM). We investigate whether different jet clustering techniques might be more or less suited to the particular final states of interest. In particular, we are interested in fully hadronic final states emerging from the decay chain of the Standard Model like Higgs boson into pairs of light Higgs states, the latter in turn decaying into b(Equation presented) pairs. We show that, the ability of selecting the multi-jet final state and to reconstruct invariant masses of the Higgs bosons from it depend strongly on the choice of acceptance cuts, resolution parameters and reconstruction algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark as a BSM signal. We then repeat the exercise for a heavy Higgs boson cascading into two SM-like Higgs states, obtaining similar results.

We assess the performance of different jet-clustering algorithms, in the presence of different resolution parameters and reconstruction procedures, in resolving fully hadronic final states emerging from the chain decay of the discovered Higgs boson into pairs of new identical Higgs states, the latter in turn decaying into bottom-antibottom quark pairs. We show that, at the large hadron collider (LHC), both the efficiency of selecting the multi-jet final state and the ability to reconstruct from it the masses of the Higgs bosons (potentially) present in an event sample depend strongly on the choice of acceptance cuts, jet-clustering algorithm as well as its settings. Hence, we indicate the optimal choice of the latter for the purpose of establishing such a benchmark Beyond the SM (BSM) signal. We then repeat the exercise for a heavy Higgs boson cascading into two SM-like Higgs states, obtaining similar results.

We study displaced signatures of sneutrino pairs potentially emerging at the Large Hadron Collider (LHC) in a Next-to-Minimal Supersymmetric Standard Model supplemented with right-handed neutrinos triggering a Type-I seesaw mechanism. We show how such signatures can be established through a heavy Higgs portal, the sneutrinos then decaying to charged leptons and charginos giving rise to further leptons or hadrons. We finally illustrate how the Yukawa parameters of neutrinos can be extracted by measuring the lifetime of the sneutrino from the displaced vertices, thereby characterising the dynamics of the underlying mechanism of neutrino mass generation. We show our numerical results for the case of both the current and High-Luminosity LHC.

Deep neural networks trained on jet images have been successful in classifying different kinds of jets. In this paper, we identify the crucial physics features that could reproduce the classification performance of the convolutional neural network in the top jet vs. QCD jet classification. We design a neural network that considers two types of sub-structural features: two-point energy correlations, and the IRC unsafe counting variables of a morphological analysis of jet images. The new set of IRC unsafe variables can be described by Minkowski functionals from integral geometry. To integrate these features into a single framework, we reintroduce two-point energy correlations in terms of a graph neural network and provide the other features to the network afterward. The network shows a comparable classification performance to the convolutional neural network. Since both networks are using IRC unsafe features at some level, the results based on simulations are often dependent on the event generator choice. We compare the classification results of Pythia 8 and Herwig 7, and a simple reweighting on the distribution of IRC unsafe features reduces the difference between the results from the two simulations.

Classification of jets with deep learning has gained significant attention in recent times. However, the performance of deep neural networks is often achieved at the cost of interpretability. Here we propose an interpretable network trained on the jet spectrum S2(R) which is a two-point correlation function of the jet constituents. The spectrum can be derived from a functional Taylor series of an arbitrary jet classifier function of energy flows. An interpretable network can be obtained by truncating the series. The intermediate feature of the network is an infrared and collinear safe C-correlator which allows us to estimate the importance of an S2(R) deposit at an angular scale R in the classification. The performance of the architecture is comparable to that of a convolutional neural network (CNN) trained on jet images, although the number of inputs and complexity of the architecture is significantly simpler than the CNN classifier. We consider two examples: one is the classification of two-prong jets which differ in color charge of the mother particle, and the other is a comparison between Pythia 8 and Herwig 7 generated jets.

Search for new physics events at the LHC mostly rely on the assumption that the events are characterized in terms of standard-reconstructed objects such as isolated photons, leptons, and jets initiated by QCD-partons. While such strategy works for a vast majority of physics beyond the standard model scenarios, there are examples aplenty where new physics give rise to anomalous objects (such as collimated and equally energetic particles, decays due to long lived particles etc.) in the detectors, which can not be classified as any of the standard-objects. Varied methods and search strategies have been proposed, each of which is trained and optimized for specific models, topologies, and model parameters. Further, as LHC keeps excluding all expected candidates for new physics, the need for a generic method/tool that is capable of finding the unexpected can not be understated. In this paper, we propose one such method that relies on the philosophy that all anomalous objects are not standard-objects. The anomaly finder, we suggest, simply is a collection of vetoes that eliminate all standard-objects up to a pre-determined acceptance rate. Any event containing at least one anomalous object (that passes all these vetoes), can be identified as a candidate for new physics. Subsequent offline analyses can determine the nature of the anomalous object as well as of the event, paving a robust way to search for these new physics scenarios in a model-independent fashion. Further, since the method relies on learning only the standard-objects, for which control samples are readily available from data, one can build the analysis in an entirely data-driven way.

In models with colored particle Q that can decay into a dark matter candidate X, the relevant collider process pp→QQ¯→XX¯+jets gives rise to events with significant transverse momentum imbalance. When the masses of Q and X are very close, the relevant signature becomes monojet-like, and Large Hadron Collider (LHC) search limits become much less constraining. In this paper, we study the current and anticipated experimental sensitivity to such particles at the High-Luminosity LHC at s=14 TeV with L= 3 ab- 1 of data and the proposed High-Energy LHC at s=27 TeV with L= 15 ab- 1 of data. We estimate the reach for various Lorentz and QCD color representations of Q. Identifying the nature of Q is very important to understanding the physics behind the monojet signature. Therefore, we also study the dependence of the observables built from the pp→ QQ¯ + j process on Q itself. Using the state-of-the-art Monte Carlo suites MadGraph5_aMC@NLO+Pythia8 and Sherpa, we find that when these observables are calculated at NLO in QCD with parton shower matching and multijet merging, the residual theoretical uncertainties are comparable to differences observed when varying the quantum numbers of Q itself. We find, however, that the precision achievable with NNLO calculations, where available, can resolve this dilemma.

We explore signatures related to squark decays in the framework of non-minimally flavour-violating supersymmetry. We consider a simplified model where the lightest squark consists of an admixture of charm and top flavour. By recasting the existing LHC searches for top and charm squarks, we show that the limits on squark masses from these analyses are significantly weakened when the top-charm mixing is sizeable. We propose a dedicated search for squarks based on the tc+ETmiss final state which enhances the experimental sensitivity for the case of high mixing, and we map its expected reach for the forthcoming runs of the LHC. We emphasize the role of analyses requiring a jet tagged as produced by the fragmentation of a charm quark in understanding the squark mixing pattern, thus providing a novel handle on new physics. Our results show that, in order to achieve full coverage of the parameter space of supersymmetric models, it is necessary to extend current experimental search programmes with analyses specifically targeting the cases where the lightest top-partner is a mixed state.

We consider a scenario of a minimal supersymmetric standard model with R-parity violation, where the lightest supersymmetric particle is the lighter bottom squark (b-1). We study the production of a bottom squark pair at the LHC and their subsequent decays through the baryon number violating operators leading to a top pair with two light quarks. Looking for both semileptonic and fully hadronic (no leptons) final states, we perform cut-based as well as multivariate analyses (MVA) to estimate the signal significance at the 13 TeV run of the LHC. We find that a cut-based analysis can probe bottom squark mass up to ∼750 GeV, which may be extended up to ∼850 GeV using MVA with 300 fb-1 integrated luminosity. The fully hadronic final state, however, is not as promising.

Light radions constitute one of the few surviving possibilities for observable new particle states at the sub-TeV level which arise in models with extra spacetime dimensions. It is already known that the 125 GeV state discovered at CERN is unlikely to be a pure radion state, since its decays resemble those of the Standard Model Higgs boson too closely. However, due to experimental errors in the measured decay widths, the possibility still remains that it could be a mixture of the radion with one (or more) Higgs states. We use the existing LHC data at 8 and 13 TeV to make a thorough investigation of this possibility. Not surprisingly, it turns out that this model is already constrained quite effectively by direct LHC searches for an additional scalar heavier than 125 GeV. We then make a detailed study of the so-called ‘conformal point’, where this heavy state practically decouples from (most of) the Standard Model fields. Some projections for the future are also included.

In the context of the minimal supersymmetric standard model (MSSM), we discuss the possibility of the lightest Higgs boson with mass Mh=98 GeV to be consistent with the 2.3σ excess observed at the LEP in the decay mode e+e-→Zh, with h→bb. In the same region of the MSSM parameter space, the heavier Higgs boson (H) with mass MH∼125 GeV is required to be consistent with the latest data on Higgs coupling measurements at the end of the 7+8 TeV LHC run with 25 fb-1 of data. While scanning the MSSM parameter space, we impose constraints coming from flavor physics, relic density of the cold dark matter as well as direct dark matter searches. We study the possibility of observing this light Higgs boson in vector boson fusion process and associated production with W/Z-boson at the high luminosity (3000 fb-1) run of the 14 TeV LHC. Our analysis shows that this scenario can hardly be ruled out even at the high luminosity run of the LHC. However, the precise measurement of the Higgs signal strength ratios can play a major role to distinguish this scenario from the canonical MSSM one.

Nonobservation of superpartners of the Standard Model particles at the early runs of the LHC provide strong motivation for introducing an R-symmetric minimal supersymmetric Standard Model. This model also comes with a pair of extra scalars which couple only to superpartners at the tree level. We demonstrate that in the case when the U(1)R symmetry is mildly broken one of these scalars develops all the properties necessary to explain the 750 GeV diphoton resonance recently observed at the LHC, as well as the nonobservation of associated signals in other channels. Some confirmatory tests in the upcoming LHC runs are proposed.

The measurement of the anomalous magnetic moment of the muon exhibits a long-standing discrepancy compared to the standard model prediction. In this paper, we concentrate on this issue in the framework of the R-parity violating minimal supersymmetric standard model. Such a scenario provides a substantial contribution to the anomalous magnetic moment of the muon while satisfying constraints from low energy experimental observables as well as the neutrino mass. In addition, we point out that the implication of such operators satisfying muon g-2 are immense from the perspective of the LHC experiment, leading to a spectacular four muon final state. We propose an analysis in this particular channel which might help to settle the debate of R-parity violation as a probable explanation for (g-2)μ.

We discuss the present status of the Higgs sector of the CP-violating minimal supersymmetric Standard Model (CPVMSSM). In the Standard Model (SM) of particle physics, the only source of CP violation is the complex phase in the Cabibbo-Kobayashi-Maskawa (CKM) matrix. By now we all know that this single phase is not large enough to explain the observed baryon asymmetry of our Universe. Hence, one require additional sources of CP violation. The MSSM with several complex phases is one such scenario. The tree-level CP invariance of the MSSM Higgs potential is broken at one-loop level in the presence of complex phases in the MSSM Lagrangian. The presence of these additional phases modifies Higgs masses, mixings and couplings significantly. These additional phases have non-trivial impact on several low-energy observables; like the electric dipole moments (EDMs) of atoms and molecules, the CP asymmetry in rare b-decays etc. We first present a brief outline of the CPVMSSM Higgs sector, and then discuss the current limits/bounds obtained from the measurements of several low-energy observables. We also comment on the current bounds coming from the high-energy collider experiments, specially the Large Electron Positron (LEP) Collider and the ongoing Large Hadron Collider (LHC) at the CERN.

A multitude of searches have already been performed by the ATLAS and CMS collaborations at the LHC to probe the heavy Higgses of the minimal supersymmetric Standard Model (MSSM) through their decay to the Standard Model particles. In this paper, we study the decay of the MSSM heavy Higgses into neutralino and chargino pairs and estimate the maximum possible branching ratios for these "ino" modes being consistent with the present LHC data. After performing a random scan of the relevant electroweakino parameters, we impose the SM 125 GeV Higgs constraints and low-energy flavor data. We choose a few representative benchmark points satisfying all the above-mentioned constraints as well as the current bounds on heavy Higgses and electroweakinos from the LHC Run-I and Run-II data. We then perform a detailed collider simulation, including fast detector effects, and analyze all the potential SM backgrounds in order to estimate the discovery reach of these heavy Higgses at the LHC. We restrict ourselves within the leptonic cascade decay modes of these heavy Higgses and study the mono-X+ET (X=W, Z) and trilepton+ET signatures in the context of a high-luminosity run of the 14 TeV LHC.

In this paper, we introduce a new variable ξ, namely, the number of tracks associated with the primary vertex, which are not parts of reconstructed objects such as jets, isolated leptons, etc. We demonstrate its usefulness in the context of new physics searches with compressed spectrum in the channel monojet+missing transverse momentum (ET). In models such as in compressed supersymmetry, events are often characterized by a rather large number of soft partons from the cascade decays, none of which results in reconstructed objects. We find that ξ, binned in pT, can discriminate these new physics events from events due to Z+jets, that is, the main background in the channel monojet+ET. The information contained in soft tracks is largely uncorrelated with traditional variables such as the effective mass, ET, pT of the jet, etc., and, therefore, can be combined with these to increase the discovery potential by more than 200% (depending on the spectra, of course). In fact we find that simple cuts on ξ(pT), when combined with cuts on the effective mass, outperforms sophisticated optimized Multivariate Data Analysis using all conventional variables. One can model the background distribution of ξ(pT) in an entirely data-driven way and make these robust against pileup by identifying the primary vertex.

Higgs signatures from the cascade decays of light top squarks are an interesting possibility in the next-to-minimal supersymmetric standard model (NMSSM). We investigate the potential reach of the light top-squark mass at the 13 TeV run of the LHC by means of five NMSSM benchmark points where this signature is dominant. These benchmark points are compatible with current Higgs coupling measurements, LHC constraints, dark matter relic density and direct-detection constraints. We consider single and dilepton search strategies, as well as the jet-substructure technique to reconstruct the Higgs bosons. We find that one can probe top-squark masses up to 1.2 TeV with 300fb-1 luminosity via the dilepton channel, while with the jet-substructure method, top-squark masses up to 1 TeV can be probed with 300fb-1 luminosity. We also investigate the possibility of the appearance of multiple Higgs peaks over the background in the fat-jet mass distribution, and conclude that such a possibility is viable only at the high-luminosity run of the 13 TeV LHC.

In this paper, we search for the regions of the phenomenological minimal supersymmetric standard model (pMSSM) parameter space where one can expect to have moderate Higgs mixing angle (α) with relatively light (up to 600 GeV) additional Higgses after satisfying the current LHC data. We perform a global fit analysis using most updated data (till December 2014) from the LHC and Tevatron experiments. The constraints coming from the precision measurements of the rare b-decays Bs→μ+μ- and b→sγ are also considered. We find that low MA(50) and high tanβ(25) regions are disfavored by the combined effect of the global analysis and flavor data. However, regions with Higgs mixing angle α∼0.1-0.8 are still allowed by the current data. We then study the existing direct search bounds on the heavy scalar/pseudoscalar (H/A) and charged Higgs boson (H±) masses and branchings at the LHC. It has been found that regions with low to moderate values of tanβ with light additional Higgses (mass ≤600 GeV) are unconstrained by the data, while the regions with tanβ>20 are excluded considering the direct search bounds by the LHC-8 data. The possibility to probe the region with tanβ≤20 at the high luminosity run of LHC are also discussed, giving special attention to the H→hh, H/A→tt¯ and H/A→τ+τ- decay modes.

We study the discovery reach of the gluino (g̃) and the lightest stop squark (t̃1) with baryonic R-parity violation (UDD type) in the context of the minimal supersymmetric standard model (MSSM) at the 14 TeV run of the LHC. We consider the gluino pair production process followed by its decay to a top quark and a real or virtual stop squark. The top quark produced from the decay of the gluino can have sufficient transverse momentum to appear as a single fat jet. We apply the jet substructure technique to tag such a hadronically decaying boosted top quark and find that gluino mass up to 1.65 TeV can be discovered whereas the exclusion limit extends up to 1.9 TeV at the 14 TeV LHC with 300fb-1 luminosity. We also briefly discuss the discovery prospect of the boosted stop squark, which may be identified as a narrow resonance in the jet mass distribution. © 2014 American Physical Society.

The ATLAS and CMS Collaborations have observed independently at the LHC a new Higgs-like particle with a mass Mh∼125GeV and properties similar to that predicted by the Standard Model (SM). Although the measurements indicate that this Higgs-like boson is compatible with the SM hypothesis, due to large uncertainties in some of the Higgs detection channels, one still has the possibility of testing this object as being a candidate for some beyond the SM physics scenarios, for example, the minimal supersymmetric Standard Model (MSSM), in the CP-conserving version (CPC-MSSM). In this paper, we evaluate the modifications of these CPC-MSSM results when CP-violating (CPV) phases are turned on explicitly, leading to the CP-violating MSSM (CPV-MSSM). We investigate the effect of the CPV phases in (some of) the soft supersymmetry (SUSY) terms on both the mass of the lightest Higgs boson h1, and the rates for the processes gg→h1→γγ, gg→h1→ZZ∗→4l, gg→h1→WW∗→lνlν, pp→Vh1→Vbb¯ and pp→Vh1→Vτ+τ-, (V≡W±,Z) at the LHC, considering the impact of the flavor constraints as well as the constraints coming from the electric dipole moment measurements. We find that it is possible to have a Higgs mass of about 125 GeV with relatively small tanβ, large At and a light top squark, which is consistent with the current SUSY particle searches at the LHC. We obtain that the imaginary part of the top and bottom Yukawa couplings can take very small but nonzero values even after satisfying the recent updates from both the ATLAS and CMS Collaborations within 1-2σ uncertainties which might be an interesting signature to look for at the future run of the LHC. Our study shows that the CPV-MSSM provides an equally possible solution (like its CP-conserving counterpart) to the recent LHC Higgs data, in fact offering very little in the way of distinction between these two SUSY models (CPC-MSSM and CPV-MSSM) at the 7 and 8 TeV runs of the LHC. Improvement in different Higgs coupling measurements is necessary in order to test the possibility of probing the small dependence on these CPV phases in the Higgs sector of the MSSM.

We discuss both the minimal supersymmetric Standard Model (MSSM) and next to MSSM scenarios in which the lightest Higgs boson with mh=98 GeV is consistent with the small excess (∼2.3σ) observed at the LEP in e+e-→Zh, with the h→bb̄ process and the heavier Higgs boson of mass close to 125 GeV as the observed candidate of the SM Higgs-like particle at the LHC. We show the allowed regions in the nondecoupling Higgs zone of MSSM parameter space which are consistent with several low energy constraints coming from heavy flavor physics, the latest experimental data on Higgs signals, and the lower limit on superparticle masses from 7 and 8 TeV LHC runs. We also implement the constraints from the relic density of the cold dark matter as obtained from the recent PLANCK data. Additionally, we discuss the possibility of observing the light Higgs boson of mass 98 GeV at the 14 TeV LHC run via pp→Vh, with h→bb̄ using the technique of jet substructure. Our analysis shows that at a 14 TeV LHC run with 300 fb-1 luminosity the signal efficiency of such a light Higgs boson is at most 2.5σ. Finally, we make a comment on the prospect of the proposed e+e- International Linear Collider to discover/exclude this light Higgs boson. © 2013 American Physical Society.

The ATLAS and CMS experiments at the CERN LHC have collected about 25 fb-1 of data each at the end of their 8TeV run, and ruled out a huge swath of parameter space in the context of Minimally Supersymmetric Standard Model (MSSM). Limits on masses of the gluino (g) and the squarks of the first two generations (q) have been pushed to above 1TeV. Light third generation squarks namely stop and sbottom of sub-TeV masses, on the other hand, are still allowed by their direct search limits. Interestingly, the discovery of a Standard Model (SM) higgs boson like particle with a mass of ∼ 125GeV favours a light third generation which is also motivated by naturalness arguments. Decays of stop and sbottom quarks can in general produce a number of distinct final states which necessitate different search strategies in the collider experiments. In this paper we, on the other hand, propose a general search strategy to look for third generation squarks in the final state which contains a top quark in the sample along with two additional hard leptons and substantial missing transverse momentum. We illustrate that a search strategy using the dileptonic MT2, the effective mass meff and jet substructure to reconstruct the hadronic top quark can be very effective to reduce the SM backgrounds. With the proposed search strategy, we estimate that the third generation squarks with masses up to about 900GeV can be probed at the 14TeV LHC with 100 fb-1 luminosity. We also interpret our results in two simplified scenarios where we consider the stop (sbottom) pair production followed by their subsequent decay to a top quark and the second lightest neutralino (lightest chargino). In this case also we find that stop (sbottom) mass up to 1TeV (0.9TeV) can be discovered at the 14TeV LHC with 100 fb -1 integrated luminosity. © SISSA 2013.

The CP-violating version of the Minimal Supersymmetric Standard Model is an example of a model where experimental data do not preclude the presence of light Higgs bosons in the range around 10-110 GeV. Such light Higgs bosons, decaying almost wholly to bb̄ pairs, may be copiously produced at the LHC but would remain inaccessible to conventional Higgs searches because of intractable QCD backgrounds. We demonstrate that a significant number of these light Higgs bosons would be boosted strongly enough for the pair of daughter b-jet pairs to appear as a single 'fat' jet with substructure. Tagging such jets could extend the discovery potential at the LHC into the hitherto-inaccessible region for light Higgs bosons. © 2012 American Physical Society.