Partha Konar - Academia.edu (original) (raw)

Papers by Partha Konar

Research paper thumbnail of Production of heavy neutrino in next-to-leading order QCD at the LHC and beyond

Journal of High Energy Physics, 2016

Majorana and pseudo-Dirac heavy neutrinos are introduced into the type-I and inverse seesaw model... more Majorana and pseudo-Dirac heavy neutrinos are introduced into the type-I and inverse seesaw models, respectively, in explaining the naturally small neutrino mass. TeV scale heavy neutrinos can also be accommodated to have a sizable mixing with the Standard Model light neutrinos, through which they can be produced and detected at the high energy colliders. In this paper we consider the Next-to-Leading Order QCD corrections to the heavy neutrino production, and study the scale variation in cross-sections as well as the kinematic distributions with different final states at 14 TeV LHC and also in the context of 100 TeV hadron collider. The repertoire of the Majorana neutrino is realized through the characteristic signature of the same-sign dilepton pair, whereas, due to a small lepton number violation, the pseudo-Dirac heavy neutrino can manifest the trileptons associated with missing energy in the final state. Using the √ s = 8 TeV, 20.3 fb −1 and 19.7 fb −1 data at the ATLAS and CMS respectively, we obtain prospective scale dependent upper bounds of the light-heavy neutrino mixing angles for the Majorana heavy neutrinos at the 14 TeV LHC and 100 TeV collider. Further exploiting a recent study on the anomalous multilepton search by CMS at √ s = 8 TeV with 19.5 fb −1 data, we also obtain the prospective scale dependent upper bounds on the mixing angles for the pseudo-Dirac neutrinos. We thus project a scale dependent prospective reach using the NLO processes at the 14 TeV LHC.

Research paper thumbnail of Dark Matter Particle Spectroscopy at the LHC: Generalizing M(T2) to Asymmetric Event Topologies

Journal of High Energy Physics, 2012

We consider SUSY-like missing energy events at hadron colliders and critically examine the common... more We consider SUSY-like missing energy events at hadron colliders and critically examine the common assumption that the missing energy is the result of two identical missing particles. In order to experimentally test this hypothesis, we generalize the subsystem M{sub T2} variable to the case of asymmetric event topologies, where the two SUSY decay chains terminate in different 'children' particles. In

Research paper thumbnail of A Storm in a

We revisit the process of transversification and agglomeration of particle momenta that are often... more We revisit the process of transversification and agglomeration of particle momenta that are often performed in analyses at hadron colliders, and show that many of the existing mass-measurement variables proposed for hadron colliders are far more closely related to each other than is widely appreciated, and indeed can all be viewed as a common mass bound specialized for a variety

Research paper thumbnail of Graviton production with 2 jets at the LHC in large extra dimensions

Journal of High Energy Physics, 2008

We study Kaluza-Klein (KK) graviton production in the large extra dimensions model via 2 jets plu... more We study Kaluza-Klein (KK) graviton production in the large extra dimensions model via 2 jets plus missing transverse momentum signatures at the LHC. We make predictions for both the signal and the dominant Zjj and W jj backgrounds, where we introduce missing P T -dependent jet selection cuts that ensure the smallness of the 2-jet rate over the 1-jet rate. With the same jet selection cuts, the distributions of the two jets and their correlation with the missing transverse momentum provide additional evidence for the production of an invisible massive object.

Research paper thumbnail of Superpartner mass measurements with 1D decomposed MT2

We propose a new model-independent technique for mass measurements in missing energy events at ha... more We propose a new model-independent technique for mass measurements in missing energy events at hadron colliders. We illustrate our method with the most challenging case of a short, single-step decay chain. We consider inclusive same-sign chargino pair production in supersymmetry, followed by leptonic decays to sneutrinos. We introduce two one-dimensional decompositions of the Cambridge MT2 variable: MT2_\parallel and MT2_\perp, on

Research paper thumbnail of Constraints on a seesaw model leading to quasidegenerate neutrinos and signatures at the LHC

Physical Review D, 2015

We consider a variant of TeV scale seesaw model in which three additional heavy right handed neut... more We consider a variant of TeV scale seesaw model in which three additional heavy right handed neutrinos are added to the standard model to generate the quasi-degenerate light neutrinos. This model is theoretically interesting since it can be fully rebuilt from the experimental data of neutrino oscillations except for an unknown factor in the Dirac Yukawa coupling. We study the constrains on this coupling coming from metastability of electro-weak vacuum. Even stronger bound comes from the lepton flavor violating decays on this model, especially in a heavy neutrino mass scenario which is within the collider reach. Bestowed with these constrained parameters, we explore the production and discovery potential coming from these heavy neutrinos at the 14 TeV run of Large Hadron Collider. Signatures with tri-lepton final state together with backgrounds are considered in a realistic simulation.

Research paper thumbnail of Looking for hints of a reconstructible seesaw model at the Large Hadron Collider

Physical Review D, 2015

We study the production of heavy neutrinos at the Large Hadron Collider (LHC) through the dominan... more We study the production of heavy neutrinos at the Large Hadron Collider (LHC) through the dominant s-channel production mode as well as the vector boson fusion (VBF) process. We consider the TeV scale minimal linear seesaw model containing two heavy singlets with opposite lepton number. This model is fully reconstructible from oscillation data apart from an overall normalization constant which can be constrained from meta-stability of the electroweak vacuum and bounds coming from lepton flavor violation (LFV) searches. Dirac nature of heavy neutrinos in this model implies suppression of the conventional samesign-dilepton signal at the LHC. We analyze the collider signatures with tri-lepton final state and missing transverse energy as well as VBF type signals which are characterized by two additional forward tagged jets. Our investigation reveals that due to stringent constraints on light-heavy mixing coming from LFV and meta-stability bounds, the model can be explored only for light to moderate mass range of heavy neutrinos. We also note that in case of a positive signal, flavor counting of the final tri-lepton channel can give information about the mass hierarchy of the light neutrinos.

Research paper thumbnail of Looking for a heavy higgsino LSP in collider and dark matter experiments

Physics Letters B, 2006

We investigate the phenomenology of a wino LSP as obtained in AMSB and some string models. The WM... more We investigate the phenomenology of a wino LSP as obtained in AMSB and some string models. The WMAP constraint on the DM relic density implies a wino LSP mass of 2.0-2.3 TeV. We find a viable signature for such a heavy wino at CLIC, operating at its highest CM energy of 5 TeV. One also expects a viable monochromatic γ-ray signal from its pair-annihilation at the galactic centre at least for cuspy DM halo profiles.

Research paper thumbnail of Constraining a class of <span class="aps-inline-formula"><math display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math></span> extended models from vacuum stability and perturbativity

Physical Review D, 2014

The precise knowledge of the Standard Model (SM) Higgs boson and top-quark masses and couplings a... more The precise knowledge of the Standard Model (SM) Higgs boson and top-quark masses and couplings are crucial to understand the physics beyond it. An SM-like Higgs boson having a mass in the range of 123-127 GeV squeezes the parameters for physics beyond the Standard Model. In recent the LHC era many TeV-scale neutrino mass models have earned much attention as they pose many interesting phenomenological aspects. We have contemplated B − L extended models which are theoretically well motivated and phenomenologically interesting, and they successfully explain neutrino mass generation. In this article we analyze the detailed structures of the scalar potentials for such models. We compute the criteria which guarantee that the vacuum is bounded from below in all directions. In addition, perturbativity (triviality) bounds are also necessitated. Incorporating all such effects, we constrain the parameters of such models by performing their renormalization-group evolutions.

Research paper thumbnail of R-parity violation in split supersymmetry

Physics Letters B, 2005

In the recently proposed 'split supersymmetry' scenario, the squark and slepton masses are allowe... more In the recently proposed 'split supersymmetry' scenario, the squark and slepton masses are allowed to be at a high scale while the gauginos and Higgsinos are within a TeV. We show that in a theory with broken R-parity, the parameter space of such a scenario allows a situation where the lightest neutralino is still stable on the cosmological scale and can be a dark matter candidate. We also separate the cases where (a) it may be invisible but not a dark matter candidate, or (b) it may decay showing a displaced vertex. It is also emphasized how the constraint on the simultaneous violation of baryon and lepton numbers gets relaxed in this scenario. PACS : 12.60.Jv, 95.35.+d, 14.80.Ly

Research paper thumbnail of RECO level $ {\sqrt {s}_{\min }} $ and subsystem improved $ {\sqrt {s}_{\min }} $ : global inclusive variables for measuring the new physics mass scale in events at hadron colliders

Journal of High Energy Physics, 2011

The variable √ s min was originally proposed in [1] as a model-independent, global and fully incl... more The variable √ s min was originally proposed in [1] as a model-independent, global and fully inclusive measure of the new physics mass scale in missing energy events at hadron colliders. In the original incarnation of

Research paper thumbnail of root_s_hat_min: a global inclusive variable for determining the mass scale of new physics in events with missing energy at hadron colliders

Journal of High Energy Physics, 2009

We propose a new global and fully inclusive variableŝ 1/2 min for determining the mass scale of n... more We propose a new global and fully inclusive variableŝ 1/2 min for determining the mass scale of new particles in events with missing energy at hadron colliders. We defineŝ 1/2 min 1/2 min is typically at the percent level, and never worse than 10%. After including the effects of initial state radiation and multiple parton interactions, the precision gets worse, but for heavy SUSY mass spectra remains ∼ 10%.

Research paper thumbnail of Dark matter particle spectroscopy at the LHC: generalizing M T2 to asymmetric event topologies

Journal of High Energy Physics, 2010

c ). As we show in several examples, quite often there is a special point along that ridge which ... more c ). As we show in several examples, quite often there is a special point along that ridge which marks the true values of the children masses. Our results allow collider experiments to probe a multi-component dark matter sector directly and without any theoretical prejudice.

Research paper thumbnail of RECO level \sqrt{s}_{min} and subsystem \sqrt{s}_{min}: improved global inclusive variables for measuring the new physics mass scale in missing energy events at hadron colliders

The variable \sqrt{s}_{min} was originally proposed in arXiv:0812.1042 as a model-independent, gl... more The variable \sqrt{s}_{min} was originally proposed in arXiv:0812.1042 as a model-independent, global and fully inclusive measure of the new physics mass scale in missing energy events at hadron colliders. In the original incarnation of \sqrt{s}_{min}, however, the connection to the new physics mass scale was blurred by the effects of the underlying event, most notably initial state radiation and multiple parton interactions. In this paper we advertize two improved variants of the \sqrt{s}_{min} variable, which overcome this problem. First we show that by evaluating the \sqrt{s}_{min} variable at the RECO level, in terms of the reconstructed objects in the event, the effects from the underlying event are significantly diminished and the nice correlation between the peak in the \sqrt{s}_{min}^{(reco)} distribution and the new physics mass scale is restored. Secondly, the underlying event problem can be avoided altogether when the \sqrt{s}_{min} concept is applied to a subsystem of th...

Research paper thumbnail of Working group report: High energy and collider physics

Pramana, 2004

This is a summary of the projects undertaken by the Working Group I on High Energy Collider Physi... more This is a summary of the projects undertaken by the Working Group I on High Energy Collider Physics at the Eighth Workshop on High Energy Physics Phenomenology (WHEPP8) held at the Indian Institute of Technology, Mumbai, January 5-16, 2004. The topics covered are (i) Higgs searches (ii) supersymmetry searches (iii) extra dimensions and (iv) linear collider.

Research paper thumbnail of Working group report: Collider and B physics

Pramana, 2003

This is summary of the activities of the working group on collider physics in the IXth Workshop o... more This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology (WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these problems by the subgroups formed during the workshop is included in this report.

Research paper thumbnail of Event shape discrimination of supersymmetry from large extra dimensions at a linear collider

Physics Letters B, 2006

The production of a charged lepton (ℓ = e, µ) pair with a large missing energy at a linear collid... more The production of a charged lepton (ℓ = e, µ) pair with a large missing energy at a linear collider is discussed as a means of distinguishing the minimal supersymmetry (MSSM) scenario from that with large extra dimensions (ADD) for parameter ranges where the total cross sections are comparable for both. Analyses in terms of event shape variables, specifically sphericity and thrust, are shown to enable a clear discrimination in this regard.

Research paper thumbnail of Next-to-leading order QCD corrections to slepton pair production via vector–boson fusion

Physics Letters B, 2007

Slepton pairs can be produced in vector-boson fusion processes at hadron colliders.

Research paper thumbnail of How to Look for Supersymmetry under the LHC Lamppost

Physical Review Letters, 2010

We apply a model-independent, agnostic approach to the collider phenomenology of supersymmetry (S... more We apply a model-independent, agnostic approach to the collider phenomenology of supersymmetry (SUSY), in which all mass parameters are taken as free inputs at the weak scale. We consider the gauginos, higgsinos, and the first two generations of sleptons and squarks, and analyze all possible mass hierarchies among them (4 × 8! = 161, 280 in total) in which the lightest superpartner is neutral, leading to missing energy. In each case, we identify the full set of the dominant (i.e. least suppressed by phase space, small mixing angles or Yukawas) decay chains originating from the lightest colored superpartner. Our exhaustive search reveals several quite dramatic yet unexplored multilepton signatures with up to 8 isolated leptons (plus possibly up to 2 massive gauge or Higgs bosons) in the final state. Such events are spectacular, background-free for all practical purposes, and may lead to a discovery in the very early stage (∼ 10 pb −1 ) of LHC operations at 7 TeV.

Research paper thumbnail of Invisible Charginos and Neutralinos from Gauge Boson Fusion: A Way to Explore Anomaly Mediation

Physical Review Letters, 2002

We point out that vector boson fusion (VBF) at the Large Hadron Collider (LHC) can lead to useful... more We point out that vector boson fusion (VBF) at the Large Hadron Collider (LHC) can lead to useful signals for charginos and neutralinos in supersymmetric scenarios where these particles are almost invisible. The proposed signals are just two forward jets with missing transverse energy.

Research paper thumbnail of Production of heavy neutrino in next-to-leading order QCD at the LHC and beyond

Journal of High Energy Physics, 2016

Majorana and pseudo-Dirac heavy neutrinos are introduced into the type-I and inverse seesaw model... more Majorana and pseudo-Dirac heavy neutrinos are introduced into the type-I and inverse seesaw models, respectively, in explaining the naturally small neutrino mass. TeV scale heavy neutrinos can also be accommodated to have a sizable mixing with the Standard Model light neutrinos, through which they can be produced and detected at the high energy colliders. In this paper we consider the Next-to-Leading Order QCD corrections to the heavy neutrino production, and study the scale variation in cross-sections as well as the kinematic distributions with different final states at 14 TeV LHC and also in the context of 100 TeV hadron collider. The repertoire of the Majorana neutrino is realized through the characteristic signature of the same-sign dilepton pair, whereas, due to a small lepton number violation, the pseudo-Dirac heavy neutrino can manifest the trileptons associated with missing energy in the final state. Using the √ s = 8 TeV, 20.3 fb −1 and 19.7 fb −1 data at the ATLAS and CMS respectively, we obtain prospective scale dependent upper bounds of the light-heavy neutrino mixing angles for the Majorana heavy neutrinos at the 14 TeV LHC and 100 TeV collider. Further exploiting a recent study on the anomalous multilepton search by CMS at √ s = 8 TeV with 19.5 fb −1 data, we also obtain the prospective scale dependent upper bounds on the mixing angles for the pseudo-Dirac neutrinos. We thus project a scale dependent prospective reach using the NLO processes at the 14 TeV LHC.

Research paper thumbnail of Dark Matter Particle Spectroscopy at the LHC: Generalizing M(T2) to Asymmetric Event Topologies

Journal of High Energy Physics, 2012

We consider SUSY-like missing energy events at hadron colliders and critically examine the common... more We consider SUSY-like missing energy events at hadron colliders and critically examine the common assumption that the missing energy is the result of two identical missing particles. In order to experimentally test this hypothesis, we generalize the subsystem M{sub T2} variable to the case of asymmetric event topologies, where the two SUSY decay chains terminate in different 'children' particles. In

Research paper thumbnail of A Storm in a

We revisit the process of transversification and agglomeration of particle momenta that are often... more We revisit the process of transversification and agglomeration of particle momenta that are often performed in analyses at hadron colliders, and show that many of the existing mass-measurement variables proposed for hadron colliders are far more closely related to each other than is widely appreciated, and indeed can all be viewed as a common mass bound specialized for a variety

Research paper thumbnail of Graviton production with 2 jets at the LHC in large extra dimensions

Journal of High Energy Physics, 2008

We study Kaluza-Klein (KK) graviton production in the large extra dimensions model via 2 jets plu... more We study Kaluza-Klein (KK) graviton production in the large extra dimensions model via 2 jets plus missing transverse momentum signatures at the LHC. We make predictions for both the signal and the dominant Zjj and W jj backgrounds, where we introduce missing P T -dependent jet selection cuts that ensure the smallness of the 2-jet rate over the 1-jet rate. With the same jet selection cuts, the distributions of the two jets and their correlation with the missing transverse momentum provide additional evidence for the production of an invisible massive object.

Research paper thumbnail of Superpartner mass measurements with 1D decomposed MT2

We propose a new model-independent technique for mass measurements in missing energy events at ha... more We propose a new model-independent technique for mass measurements in missing energy events at hadron colliders. We illustrate our method with the most challenging case of a short, single-step decay chain. We consider inclusive same-sign chargino pair production in supersymmetry, followed by leptonic decays to sneutrinos. We introduce two one-dimensional decompositions of the Cambridge MT2 variable: MT2_\parallel and MT2_\perp, on

Research paper thumbnail of Constraints on a seesaw model leading to quasidegenerate neutrinos and signatures at the LHC

Physical Review D, 2015

We consider a variant of TeV scale seesaw model in which three additional heavy right handed neut... more We consider a variant of TeV scale seesaw model in which three additional heavy right handed neutrinos are added to the standard model to generate the quasi-degenerate light neutrinos. This model is theoretically interesting since it can be fully rebuilt from the experimental data of neutrino oscillations except for an unknown factor in the Dirac Yukawa coupling. We study the constrains on this coupling coming from metastability of electro-weak vacuum. Even stronger bound comes from the lepton flavor violating decays on this model, especially in a heavy neutrino mass scenario which is within the collider reach. Bestowed with these constrained parameters, we explore the production and discovery potential coming from these heavy neutrinos at the 14 TeV run of Large Hadron Collider. Signatures with tri-lepton final state together with backgrounds are considered in a realistic simulation.

Research paper thumbnail of Looking for hints of a reconstructible seesaw model at the Large Hadron Collider

Physical Review D, 2015

We study the production of heavy neutrinos at the Large Hadron Collider (LHC) through the dominan... more We study the production of heavy neutrinos at the Large Hadron Collider (LHC) through the dominant s-channel production mode as well as the vector boson fusion (VBF) process. We consider the TeV scale minimal linear seesaw model containing two heavy singlets with opposite lepton number. This model is fully reconstructible from oscillation data apart from an overall normalization constant which can be constrained from meta-stability of the electroweak vacuum and bounds coming from lepton flavor violation (LFV) searches. Dirac nature of heavy neutrinos in this model implies suppression of the conventional samesign-dilepton signal at the LHC. We analyze the collider signatures with tri-lepton final state and missing transverse energy as well as VBF type signals which are characterized by two additional forward tagged jets. Our investigation reveals that due to stringent constraints on light-heavy mixing coming from LFV and meta-stability bounds, the model can be explored only for light to moderate mass range of heavy neutrinos. We also note that in case of a positive signal, flavor counting of the final tri-lepton channel can give information about the mass hierarchy of the light neutrinos.

Research paper thumbnail of Looking for a heavy higgsino LSP in collider and dark matter experiments

Physics Letters B, 2006

We investigate the phenomenology of a wino LSP as obtained in AMSB and some string models. The WM... more We investigate the phenomenology of a wino LSP as obtained in AMSB and some string models. The WMAP constraint on the DM relic density implies a wino LSP mass of 2.0-2.3 TeV. We find a viable signature for such a heavy wino at CLIC, operating at its highest CM energy of 5 TeV. One also expects a viable monochromatic γ-ray signal from its pair-annihilation at the galactic centre at least for cuspy DM halo profiles.

Research paper thumbnail of Constraining a class of <span class="aps-inline-formula"><math display="inline"><mi>B</mi><mo>−</mo><mi>L</mi></math></span> extended models from vacuum stability and perturbativity

Physical Review D, 2014

The precise knowledge of the Standard Model (SM) Higgs boson and top-quark masses and couplings a... more The precise knowledge of the Standard Model (SM) Higgs boson and top-quark masses and couplings are crucial to understand the physics beyond it. An SM-like Higgs boson having a mass in the range of 123-127 GeV squeezes the parameters for physics beyond the Standard Model. In recent the LHC era many TeV-scale neutrino mass models have earned much attention as they pose many interesting phenomenological aspects. We have contemplated B − L extended models which are theoretically well motivated and phenomenologically interesting, and they successfully explain neutrino mass generation. In this article we analyze the detailed structures of the scalar potentials for such models. We compute the criteria which guarantee that the vacuum is bounded from below in all directions. In addition, perturbativity (triviality) bounds are also necessitated. Incorporating all such effects, we constrain the parameters of such models by performing their renormalization-group evolutions.

Research paper thumbnail of R-parity violation in split supersymmetry

Physics Letters B, 2005

In the recently proposed 'split supersymmetry' scenario, the squark and slepton masses are allowe... more In the recently proposed 'split supersymmetry' scenario, the squark and slepton masses are allowed to be at a high scale while the gauginos and Higgsinos are within a TeV. We show that in a theory with broken R-parity, the parameter space of such a scenario allows a situation where the lightest neutralino is still stable on the cosmological scale and can be a dark matter candidate. We also separate the cases where (a) it may be invisible but not a dark matter candidate, or (b) it may decay showing a displaced vertex. It is also emphasized how the constraint on the simultaneous violation of baryon and lepton numbers gets relaxed in this scenario. PACS : 12.60.Jv, 95.35.+d, 14.80.Ly

Research paper thumbnail of RECO level $ {\sqrt {s}_{\min }} $ and subsystem improved $ {\sqrt {s}_{\min }} $ : global inclusive variables for measuring the new physics mass scale in events at hadron colliders

Journal of High Energy Physics, 2011

The variable √ s min was originally proposed in [1] as a model-independent, global and fully incl... more The variable √ s min was originally proposed in [1] as a model-independent, global and fully inclusive measure of the new physics mass scale in missing energy events at hadron colliders. In the original incarnation of

Research paper thumbnail of root_s_hat_min: a global inclusive variable for determining the mass scale of new physics in events with missing energy at hadron colliders

Journal of High Energy Physics, 2009

We propose a new global and fully inclusive variableŝ 1/2 min for determining the mass scale of n... more We propose a new global and fully inclusive variableŝ 1/2 min for determining the mass scale of new particles in events with missing energy at hadron colliders. We defineŝ 1/2 min 1/2 min is typically at the percent level, and never worse than 10%. After including the effects of initial state radiation and multiple parton interactions, the precision gets worse, but for heavy SUSY mass spectra remains ∼ 10%.

Research paper thumbnail of Dark matter particle spectroscopy at the LHC: generalizing M T2 to asymmetric event topologies

Journal of High Energy Physics, 2010

c ). As we show in several examples, quite often there is a special point along that ridge which ... more c ). As we show in several examples, quite often there is a special point along that ridge which marks the true values of the children masses. Our results allow collider experiments to probe a multi-component dark matter sector directly and without any theoretical prejudice.

Research paper thumbnail of RECO level \sqrt{s}_{min} and subsystem \sqrt{s}_{min}: improved global inclusive variables for measuring the new physics mass scale in missing energy events at hadron colliders

The variable \sqrt{s}_{min} was originally proposed in arXiv:0812.1042 as a model-independent, gl... more The variable \sqrt{s}_{min} was originally proposed in arXiv:0812.1042 as a model-independent, global and fully inclusive measure of the new physics mass scale in missing energy events at hadron colliders. In the original incarnation of \sqrt{s}_{min}, however, the connection to the new physics mass scale was blurred by the effects of the underlying event, most notably initial state radiation and multiple parton interactions. In this paper we advertize two improved variants of the \sqrt{s}_{min} variable, which overcome this problem. First we show that by evaluating the \sqrt{s}_{min} variable at the RECO level, in terms of the reconstructed objects in the event, the effects from the underlying event are significantly diminished and the nice correlation between the peak in the \sqrt{s}_{min}^{(reco)} distribution and the new physics mass scale is restored. Secondly, the underlying event problem can be avoided altogether when the \sqrt{s}_{min} concept is applied to a subsystem of th...

Research paper thumbnail of Working group report: High energy and collider physics

Pramana, 2004

This is a summary of the projects undertaken by the Working Group I on High Energy Collider Physi... more This is a summary of the projects undertaken by the Working Group I on High Energy Collider Physics at the Eighth Workshop on High Energy Physics Phenomenology (WHEPP8) held at the Indian Institute of Technology, Mumbai, January 5-16, 2004. The topics covered are (i) Higgs searches (ii) supersymmetry searches (iii) extra dimensions and (iv) linear collider.

Research paper thumbnail of Working group report: Collider and B physics

Pramana, 2003

This is summary of the activities of the working group on collider physics in the IXth Workshop o... more This is summary of the activities of the working group on collider physics in the IXth Workshop on High Energy Physics Phenomenology (WHEPP-9) held at the Institute of Physics, Bhubaneswar, India in January 2006. Some of the work subsequently done on these problems by the subgroups formed during the workshop is included in this report.

Research paper thumbnail of Event shape discrimination of supersymmetry from large extra dimensions at a linear collider

Physics Letters B, 2006

The production of a charged lepton (ℓ = e, µ) pair with a large missing energy at a linear collid... more The production of a charged lepton (ℓ = e, µ) pair with a large missing energy at a linear collider is discussed as a means of distinguishing the minimal supersymmetry (MSSM) scenario from that with large extra dimensions (ADD) for parameter ranges where the total cross sections are comparable for both. Analyses in terms of event shape variables, specifically sphericity and thrust, are shown to enable a clear discrimination in this regard.

Research paper thumbnail of Next-to-leading order QCD corrections to slepton pair production via vector–boson fusion

Physics Letters B, 2007

Slepton pairs can be produced in vector-boson fusion processes at hadron colliders.

Research paper thumbnail of How to Look for Supersymmetry under the LHC Lamppost

Physical Review Letters, 2010

We apply a model-independent, agnostic approach to the collider phenomenology of supersymmetry (S... more We apply a model-independent, agnostic approach to the collider phenomenology of supersymmetry (SUSY), in which all mass parameters are taken as free inputs at the weak scale. We consider the gauginos, higgsinos, and the first two generations of sleptons and squarks, and analyze all possible mass hierarchies among them (4 × 8! = 161, 280 in total) in which the lightest superpartner is neutral, leading to missing energy. In each case, we identify the full set of the dominant (i.e. least suppressed by phase space, small mixing angles or Yukawas) decay chains originating from the lightest colored superpartner. Our exhaustive search reveals several quite dramatic yet unexplored multilepton signatures with up to 8 isolated leptons (plus possibly up to 2 massive gauge or Higgs bosons) in the final state. Such events are spectacular, background-free for all practical purposes, and may lead to a discovery in the very early stage (∼ 10 pb −1 ) of LHC operations at 7 TeV.

Research paper thumbnail of Invisible Charginos and Neutralinos from Gauge Boson Fusion: A Way to Explore Anomaly Mediation

Physical Review Letters, 2002

We point out that vector boson fusion (VBF) at the Large Hadron Collider (LHC) can lead to useful... more We point out that vector boson fusion (VBF) at the Large Hadron Collider (LHC) can lead to useful signals for charginos and neutralinos in supersymmetric scenarios where these particles are almost invisible. The proposed signals are just two forward jets with missing transverse energy.