arXiv subjects

AseshKrishna Datta

Publications and source records attributed to AseshKrishna Datta.

32 records · Page 2Linked to original sources

arXiv2012

Non-minimal Universal Extra Dimensions: The strongly interacting sector at the Large Hadron Collider

We work out the strongly interacting sector of a non-minimal Universal Extra Dimension (nmUED) scenario with one flat extra spatial dimension orbifolded on S^1/Z_2 in the presence of brane-localized kinetic and Yukawa terms. On compactification, these terms are known to have significant, nontrivial impact on the masses and the couplings of the Kaluza-Klein (KK) excitations. We study the masses of the level `1' KK gluon and the quarks and find the modified strong interaction vertices involving these particles. The scenario conserves KK parity. Possibility of significant level-mixing among the quarks from different KK-levels is pointed out with particular reference to the top quark sector. Cross sections for various generic final states involving level `1' KK-gluon and KK-quarks from first two generations are estimated at the Large Hadron Collider (LHC) via an implementation of the scenario in MadGraph-5 with the help of FeynRules. The decay branching fractions of both strong and weakly interacting KK excitations are studied to estimate yields in various different final states involving jets, leptons and missing energy. These are used to put some conservative constraints on the nmUED parameter space using the latest LHC data. Nuances of the scenario are elucidated with reference to the minimal Universal Extra Dimension (mUED) and Supersymmetry (SUSY) and their implications for the LHC are discussed.

hep-ph↗

arXiv2011

Entangled System of Squarks from the Third Generation at the Large Hadron Collider

In the Minimal Supersymmetric extension of the Standard Model (MSSM) squarks from the third generation, i.e., the bottom and the top squarks, have a common set of parameters that determine their masses and couplings. These are in the form of the common soft mass for the left handed squark from the third generation ($m_{\widetilde{Q}_{_{3L}}}$), the supersymmetry conserving Higgsino mass parameter $μ$ and $\tanβ$, the ratio of vacuum expectation values of the two Higgs doublets. This leads to an interesting possibility that the systems involving the bottom and the top squarks might get correlated in a non-trivial way even in an unconstrained setup. In this work, phenomenology of the bottom and the top squarks is studied at the Large Hadron Collider which exploits such a possibility with a particular emphasis on bottom squark decaying to top squark and $W$ boson. Possibility of reconstructing multiple $W$ bosons in the final state is identified to be the key in probing the squark mixing angles. Further entanglement of the electroweak gaugino-higgsino sector is also not impossible in scenarios based on phenomenological MSSM while for highly constrained scenarios like minimal supergravity/constrained MSSM such entanglements are trivially forced upon.

hep-ph↗

arXiv2010

Minimal Universal Extra Dimensions in CalcHEP/CompHEP

We present an implementation of the model of minimal universal extra dimensions (MUED) in CalcHEP/CompHEP. We include all level-1 and level-2 Kaluza-Klein (KK) particles outside the Higgs sector. The mass spectrum is automatically calculated at one loop in terms of the two input parameters in MUED: the radius of the extra dimension and the cut-off scale of the model. We implement both the KK number conserving and the KK number violating interactions of the KK particles. We also account for the proper running of the gauge coupling constants above the electroweak scale. The implementation has been extensively cross-checked against known analytical results in the literature and numerical results from other programs. Our files are publicly available and can be used to perform various automated calculations within the MUED model.

hep-ph↗

arXiv2009

Search for Higgs bosons of the Universal Extra Dimensions at the Large Hadron Collider

The Higgs sector of the Universal Extra Dimensions (UED) has a rather involved setup. With one extra space dimension, the main ingredients to the construct are the higher Kaluza-Klein (KK) excitations of the Standard Model Higgs boson and the fifth components of the gauge fields which on compactification appear as scalar degrees of freedom and can mix with the former thus leading to physical KK-Higgs states of the scenario. In this work, we explore in detail the phenomenology of such a Higgs sector of the UED with the Large Hadron Collider (LHC) in focus. We work out relevant decay branching fractions involving the KK-Higgs excitations. Possible production modes of the KK-Higgs bosons are then discussed with an emphasis on their associated production with the third generation KK-quarks and that under the cascade decays of strongly interacting UED excitations which turn out to be the only phenomenologically significant modes. It is pointed out that the collider searches of such Higgs bosons face generic hardship due to soft end-products which result from severe degeneracies in the masses of the involved excitations in the minimal version of the UED (MUED). Generic implications of either observing some or all of the KK-Higgs bosons at the LHC are discussed.

hep-ph↗

arXiv2008

Non-universal gaugino and scalar masses, hadronically quiet trileptons and the Large Hadron Collider

We investigate the parameter space of the minimal supersymmetric Standard Model (MSSM) where the gluino and squark masses are much above 1 TeV but the remaining part of the sparticle spectrum is accessible to the Large Hadron Collider at CERN. After pointing out that such a scenario may constitute an important benchmark of gaugino/scalar non-universality, we find that hadronically quiet trileptons are rather useful signals for it. Regions of the parameter space, where the signal is likely to be appreciable, are identified through a detailed scan. The advantage of hadronically quiet trileptons over other types of signals is demonstrated.

hep-ph↗

arXiv2008

Signatures of gaugino mass non-universality in cascade Higgs production at the LHC

Supersymmetric cascades, involving charginos and neutralinos at various stages, contribute in a significant way to Higgs production at the LHC. We explore the nature of such cascades, completely relaxing the universality of the gaugino masses. It is found that the deviation from the scenario with universal gaugino masses would be reflected in the relative production rates for the lightest Higgs and the charged Higgses, two characteristic particles of an extended Higgs sector.

hep-ph↗

arXiv2008

Non-universal scalar masses: a signal-based analysis for the Large Hadron Collider

We study the possible signatures of non-universal scalar masses in supersymmetry at the Large Hadron Collider (LHC). This is done, following our recent study on gaugino non-universality, via a multichannel analysis, based largely on the ratios of event rates for different final states, aimed at minimizing irregularity in the pattern due to extraneous effects and errors. We have studied (a) squark-slepton non-universality, (b) non-universality in sfermion masses of the third family, (c) the effects of $SO(10) D$-terms in supersymmetric Grand Unified Theories. After presenting an elaborate numerical analysis of like- and opposite-sign dileptons, inclusive and hadronically quiet trileptons as well as inclusive jet final states, we point out specific features of the spectrum in each case, which can be differentiated in the above channels from the spectrum for a minimal supergravity scenario with a universal scalar mass at high scale. The event selection criteria, and the situations where the signals are sizable enough for a comparatve study, are also delineated. It is found that, with some exceptions, the trilepton channels are likely to be especially useful for this purpose.

hep-ph↗

arXiv2007

Distinguishing the Littlest Higgs model with T-parity from supersymmetry at the LHC using trileptons

We analyse hadronically quiet trilepton signatures in the T-parity conserving Littlest Higgs model and in R-parity conserving supersymmetry at the Large Hadron Collider. We identify the regions of the parameter space where such signals can reveal the presence of these new physics models above the Standard Model background and distinguish them from each other, even in a situation when the mass spectrum of the Littlest Higgs model resembles the supersymmetric pattern.

hep-ph↗

arXiv2007

Associated Higgs Production in CP-violating supersymmetry: probing the `open hole' at the Large Hadron Collider

A benchmark CP-violating supersymmetric scenario (known in the literature as `CPX-scenario') 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 Large Electron Positron Collider data. This can be done through associated production of Higgs bosons with top quark and top squark pairs leading to the signal \emph{dilepton + $\leq{5}$ jets (including 3 b-jets) + missing ${p_T}$}. Efficient discrimination of such a CP-violating supersymmetric scenario from other contending ones is also possible at the LHC with a moderate volume of data.

hep-ph↗

arXiv2007

Non-universal gaugino masses: a signal-based analysis for the Large Hadron Collider

We discuss the signals at the Large Hadron Collider (LHC) for scenarios with non-universal gaugino masses in supersymmetric (SUSY) theories. We perform a multichannel analysis, and consider the ratios of event rates in different channels such as $jets + {E}_T/ $, $same$ - and $opposite$-$sign dileptons$ $+jets+ {E}_T/ $, as well as $single-lepton$ and $trilepton$ final states together with $jets + {E}_T/ $ . Low-energy SUSY spectra corresponding to high-scale gaugino non-universality arising from different breaking schemes of SU(5) as well as SO(10) Grand Unified (GUT) SUSY models are considered, with both degenerate low-energy sfermion masses and those arising from a supergravity scenario. We present the numerical predictions over a wide range of the parameter space using the event generator {\tt Pythia}, specifying the event selection criteria and pointing out regions where signals are likely to be beset with backgrounds. Certain broad features emerge from the study, which may be useful in identifying the signatures of different GUT breaking schemes and distinguishing them from a situation with a universal gaugino mass at high scale. The absolute values of the predicted event rates for different scenarios are presented together with the various event ratios, so that these can also be used whenever necessary.

hep-ph↗

arXiv2005

Is it SUSY?

If a signal for physics beyond the Standard Model is observed at the Tevatron collider or LHC, we will be eager to interpret it. Because only certain observables can be studied at a hadron collider, it will be difficult or impossible to measure masses and spins that could easily establish what physics was being seen. Nevertheless, different underlying physics implies different signatures. We examine the main signatures for supersymmetry, with some emphasis on recognizing supersymmetry in parts of parameter space where generic signatures are reduced or absent. We also consider how to distinguish supersymmetry from alternatives that most closely resemble it, such as Universal Extra Dimensions (UED). Using the robust connection between spins and production cross section, we think it will not be difficult to distinguish UED from supersymmetry. We expect that by considering patterns of signatures it is very likely that it will not be difficult to find a compelling interpretation of any signal of new physics.

hep-ph↗

arXiv2005

Discrimination of Supersymmetry and Universal Extra Dimensions at Hadron Colliders

We contrast the experimental signatures of low energy supersymmetry and the model of Universal Extra Dimensions and discuss various methods for their discrimination at hadron colliders. We study the discovery reach of the Tevatron and the LHC for level 2 Kaluza-Klein modes, which would indicate the presence of extra dimensions. We find that with 100 ${\rm fb}^{-1}$ of data the LHC will be able to discover the $γ_2$ and $Z_2$ KK modes as separate resonances if their masses are below 2 TeV. We also investigate the possibility to differentiate the spins of the superpartners and KK modes by means of the asymmetry method of Barr.

hep-ph↗

arXiv2005

Contrasting Supersymmetry and Universal Extra Dimensions at the CLIC Multi-TeV e+e- Collider

Universal extra dimensions and supersymmetry have rather similar experimental signatures at hadron colliders. The proper interpretation of an LHC discovery in either case may therefore require further data from a lepton collider. In this paper we identify methods for discriminating between the two scenarios at the linear collider. We study the processes of Kaluza-Klein muon pair production in universal extra dimensions in parallel to smuon pair production in supersymmetry, accounting for the effects of detector resolution, beam-beam interactions and accelerator induced backgrounds. We find that the angular distributions of the final state muons, the energy spectrum of the radiative return photon and the total cross-section measurement are powerful discriminators between the two models. Accurate determination of the particle masses can be obtained both by a study of the momentum spectrum of the final state leptons and by a scan of the particle pair production thresholds. We also calculate the production rates of various Kaluza-Klein particles and discuss the associated signatures.

hep-ph↗

arXiv2005

Cabibbo Haze in Lepton Mixing

Quark-lepton unification suggests Cabibbo-sized effects in lepton mixings, which we call Cabibbo haze. We give simple examples and explore possible Wolfenstein-like parametrizations of the MNSP matrix which incorporate leptonic Cabibbo shifts. We find that the size of the CHOOZ angle is not always correlated with the observability of CP violation.

hep-ph↗