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D. P. Roy

Publications and source records attributed to D. P. Roy.

At least 37 records · Page 2Linked to original sources
arXiv2008

Probing a Supersymmetric Model for Neutrino Masses at Ultrahigh Energy Neutrino Telescopes

A bilinear R-Parity breaking SUSY model for neutrino mass and mixing predicts the lightest superparticle to decay mainly into a pair of tau leptons or b quarks along with a neutrino for relatively light SUSY spectra. This leads to a distinctive triple bang signature of SUSY events at ultrahigh energy neutrino telescopes like IceCube or Antares. While the expected signal size is only marginal at IceCube, it will be promising for a future multi-km^3 size neutrino telescope.

hep-ph↗
arXiv2007

Probing the Two Greatest Mysteries of the Universe

The neutrinoless double beta decay and the direct dark matter detection experiments probe the origins of the two greatest mysteries of the universe, i.e. the baryon asymmetry and the invisible or dark matter. The underlying theoretical ideas are briefly discussed along with the experimental prospects.

hep-ph↗
arXiv2007

SUSY Search in Future Collider and Dark Matter Experiments

The lightest superparticle in the MSSM is expected to be a Bino, Higgsino or Wino. We consider the dark matter abundance constraint on these LSP scenarios in the minimal SUGRA and AMSB models. We discuss the resulting collider signals for the Bino LSP at LHC and the Higgsino and Wino LSP at CLIC. The Bino, Higgsino and Wino LSP signals in dark matter experiments are also discussed briefly. We conclude with a discussion of these LSP scenarios in nonminimal SUSY models.

hep-ph↗
arXiv2007

Natural Dark Matter in SUSY GUTs with Non-universal Gaugino Masses

We consider neutralino dark matter within the framework of SUSY GUTs with non-universal gaugino masses. In particular we focus on the case of SU(5) with a SUSY breaking F-term in the 1, 24, 75 and 200 dimensional representations. We discuss the 24 case in some detail, and show that the bulk dark matter region cannot be accessed. We then go on to consider the admixture of the singlet SUSY breaking F-term with one of the 24, 75 or 200 dimensional F-terms, and show that in these cases it becomes possible to access the bulk regions corresponding to low fine-tuned dark matter. Our results are presented in the $(M_1,M_2)$ plane for fixed $M_3$ and so are useful for considering general GUT models, as well as more general non-universal gaugino models.

hep-ph↗
arXiv2007

Looking for a heavy wino LSP in collider and dark matter experiments

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.

hep-ph↗
arXiv2006

Signature of heavy Charged Higgs Boson at LHC in the 1 and 3 prong Hadronic Tau Decay channels

We have done a fast simulation analysis of the charged Higgs signal at LHC in the 1 and 3 prong hadronic $τ$-jet channels along with the $t \bar t$ background. The $τ$ polarization was effectively used to suppress the background in both the channels. Combining this with appropriate cuts on the $p_T$ of the $τ$-jet, the missing $E_T$ and the azimuthal angle between them reduces the background below the signal level. Consequently one gets a viable charged higgs signal up to a mass range of 600-700 GeV at moderate to large $\tanβ$.

hep-ph↗
arXiv2005

Charged Higgs Boson Search at the LHC

This review starts with a brief introduction to the charged Higgs boson $(H^\pm)$ in the Minimal Supersymmetric Standard Model (MSSM). It then discusses the prospects of a relatively light $H^\pm$ boson search via top quark decay and finally a heavy $H^\pm$ boson search at LHC. The viable channels for $H^\pm$ search are discussed, with particular emphasis on the $H^\pm -> tau+nu$ decay channel.

hep-ph↗
arXiv2005

Looking for a Heavy Higgsino LSP in Collider and Dark Matter Experiments

A large part of the mSUGRA parameter space satisfying the WMAP constraint on the dark matter relic density corresponds to a higgsino LSP of mass $\simeq 1$ TeV. We find a promising signal for this LSP at CLIC, particularly with polarized electron and positron beams. One also expects a viable monochromatic $γ$-ray signal from its pair annihilation at the galactic center at least for cuspy DM halo profiles. All these results hold equally for the higgsino LSP of other SUSY models like the non-universal scalar or gaugino mass models and the so-called inverted hierarchy and more minimal supersymmetry models.

hep-ph↗
arXiv2005

Probing the CP-violating light neutral Higgs in the charged Higgs decay at the LHC

The CP-violating MSSM allows existence of a light neutral Higgs boson ($M_{H_1} \lapp 50$ GeV) in the CPX scenario in the low $\tan β(\lapp 5)$ region, which could have escaped the LEP searches due to a strongly suppressed $H_1 Z Z$ coupling. This parameter space corresponds to a relatively light $H^\pm$ ($M_{H^\pm} < M_t$), which is predicted to decay dominantly into the $W H_1$ channel. Thus one expects to see a striking $t \bar t$ signal at the LHC, where one of the top quarks decays into the $bb \bar b W$ channel, via $t \to b H^\pm, H^\pm \to W H_1$ and $H_1 \to b \bar b$. The characteristic correlation between the $b \bar b$, $b \bar b W$ and $b b \bar b W$ invariant mass peaks is expected to make this signal practically free of the SM background. Our parton level Monte Carlo simulation yields upto 5000 events, for ${\cal L} = 30$ fb$^{-1}$, over the parameter space of interest, after taking into account the b-tagging efficiency for three or more b-tagged jets.

hep-ph↗
arXiv2005

Using Tau Polarization to Discriminate between SUSY Models and Determine SUSY Parameters at ILC

In many SUSY models the first SUSY signal in the proposed International Linear Collider is expected to come from the pair production of $\tildeτ_1$, followed by its decay into $τ$+LSP. We study a simple and robust method of measuring the polarization of this $τ$ in its 1-prong hadronic decay channel,and show how it can be used to discriminate between SUSY models and to determine SUSY parameters.

hep-ph↗
arXiv2004

Update of the solar neutrino oscillation analysis with the 766 Ty KamLAND spectrum

We investigate the impact of the 766.3 Ty KamLAND spectrum data on the determination of the solar neutrino oscillation parameters. We show that the observed spectrum distortion in the KamLAND experiment firmly establishes $Δm^2_{21}$ to lie in the low-LMA solution region. The high-LMA solution is excluded at more than 4$σ$ by the global solar neutrino and KamLAND spectrum data. The maximal solar neutrino mixing is ruled out at $6σ$ level. The $3σ$ allowed region in the $Δm^2_{21}-\sin^2θ_{12}$ plane is found to be remarkably stable with respect to leaving out the data from one of the solar neutrino experiments from the global analysis. We perform a three flavor neutrino oscillation analysis of the global solar neutrino and KamLAND spectrum data as well. The $3σ$ upper limit on $\sin^2θ_{13}$ is found to be $ \sin^2θ_{13} <0.055$. We derive predictions for the CC to NC event rate ratio and day-night (D-N) asymmetry in the CC event rate, measured in the SNO experiment, and for the suppression of the event rate in the BOREXINO and LowNu experiments. Prospective high precision measurements of the solar neutrino oscillation parameters are also discussed.

hep-ph↗
arXiv2004

Solar Neutrino Oscillation - An Overview

After a brief summary of the neutrino oscillation formalism and the solar neutrino sources and experiments I discuss the matter effect on solar neutrino oscillation. Then I discuss how the resulting alternative solutions are experimentally resolved in favour of the LMA solution, with particular exphasis on the SK, SNO and KL data.

hep-ph↗
arXiv2004

Summary of the Activities of the Working Group I on High Energy and Collider Physics

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.

hep-ph↗
arXiv2004

Working Group Report: Neutrino and Astroparticle Physics

This is the report of neutrino and astroparticle physics working group at WHEPP-8. We present the discussions carried out during the workshop on selected topics in the above fields and also indicate progress made subsequently. The neutrino physics subgroup studied the possibilites of constraining neutrino masses, mixing and CPT violation in lepton sector from future experiments. Neutrino mass models in the context of abelian horizontal symmetries, warped extra dimensions and in presence of triplet Higgs were studied. Effect of threshold corrections on radiative magnification of mixing angles was investigated. The astroparticle physics subgroup focused on how various particle physics inputs affect the CMBR fluctuation spectrum, and on brane cosmology. This report also contains an introduction on how to use the publicly available code CMBFAST to calculate the CMBR fluctuations.

hep-ph↗
arXiv2004

The Charged Higgs Boson Search at LHC

This review starts with a brief introduction to the charged Higgs boson $(H^\pm)$ in the Minimal Supersymmetric Standard Model (MSSM). It then discusses the prospects of a relatively light $H^\pm$ boson search via top quark decay and finally a heavy $H^\pm$ boson search at LHC. The viable channels for $H^\pm$ search are discussed, with particular emphasis on the $H^\pm \to τν$ decay channel.

hep-ph↗
arXiv2004

Looking for the Charged Higgs Boson

This review article starts with a brief introduction to the charged Higgs boson (H^\pm) in the Minimal Supersymmetric Standard Model (MSSM). It then discusses the prospects of a relatively light H^\pm boson search via top quark decay at Tevatron/LHC, and finally a heavy H^\pm boson search at LHC. The viable channels for H^\pm search are identified in both the cases, with particular emphasis on the H^\pm --> tau + nu decay channel. The effects of NLO QCD correction in the SM as well as the MSSM are discussed briefly.

hep-ph↗
arXiv2003

History of exotic Meson (4-quark) and Baryon (5-quark) States

I briefly review the history of exotic meson (4-quark) and baryon (5-quark) states, which is rooted in the formalism of Regge pole and duality. There are robust model-independent predictions for the exchange of 4-quark (Baryonium) Regge trajectories in several processes, which are strongly supported by experiment. On the other hand the predictions for the spectroscopy of 4-quark resonances are based on specific QCD inspired models, with some experimental support. The corresponding predictions for the recently discovered exotic baryon (Pentaquark) state are briefly discussed.

hep-ph↗
arXiv2003

Constraints on neutrino oscillation parameters from the SNO salt phase data

The physics implications of the just published salt phase data from the SNO experiment are examined. The effect of these data on the allowed ranges of the solar neutrino oscillation parameters, $Δ_m^2_{21}$ and $\sin^2θ_{12}$, are studied in the cases of two- and three- neutrino mixing. In the latter case we derive an upper limit on the angle $θ_{13}$. Constraints on the solar $ν_e$ transitions into a mixture of active and sterile neutrinos are also presented. Finally, we give predictions for the day-night asymmetry in the SNO experiment, for the event rate in the BOREXINO and LowNu experiments, and discuss briefly the constraints on the solar neutrino oscillation parameters which can be obtained with prospective KamLAND data.

hep-ph↗