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Bhattacherjee B.,University of Tokyo | Choudhury A.,Indian Institute of Science | Ghosh K.,Oklahoma State University | Poddar S.,Netaji Nagar Day College
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

In this work we study the collider phenomenology of a compressed supersymmetric model with the gluino (gËœ) and the lightest neutralino (χËœ10). All other sparticles are assumed to be heavy. We consider gluino pair production at the 14 TeV LHC and present the mass reach of the gluino as a function of mass splitting between the gluino and the lightest neutralino. We find that the gluino mass below 1 TeV can be excluded at 95% C.L. with an integrated luminosity of 100 fb-1 for the extreme degenerate case where the mass separation between the gluino and the lightest neutralino is about 20 GeV. On the other hand, the lower bound on the mass of the gluino increases to 1.2-1.3 TeV if the mass splitting between the gluino and χËœ10 is about 200 GeV. This result shows that for a degenerate gluino, the current mass limit may approximately extend up to 400-500 GeV at the 14 TeV LHC. © 2014 American Physical Society.

Chakraborty A.,Tata Institute of Fundamental Research | Ghosh D.K.,Indian Association for The Cultivation of Science | Mondal S.,Harish Chandra Research Institute | Poddar S.,Netaji Nagar Day College | Sengupta D.,CNRS Laboratory of Subatomic Physics & Cosmology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

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. © 2015 American Physical Society.

Datta A.,Indian Institute of Science | Datta A.,University of Calcutta | Poddar S.,Netaji Nagar Day College
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2012

We propose a new search strategy based on the event shape variables for new physics models where the separations among the masses of the particles in the spectrum are small. Collider signature of these models, characterized by low p T leptons/jets and low missing p T, are known to be difficult to look for. The conventional search strategies involving hard cuts may not work in such situations. As a case study, we have investigated the hitherto neglected jets+missing E T signature - known to be a challenging one - arising from the pair productions and decay of n=1 KK-excitations of gluons and quarks in the minimal Universal Extra Dimension (mUED) model. Judicious use of the event shape variables enables us to reduce the Standard Model backgrounds to a negligible level. We have shown that in mUED, R -1 up to 850GeV can be explored or ruled out with 12 fb -1 of integrated luminosity at the 7 TeV run of the LHC. We also discuss the prospects of employing these variables for searching other beyond Standard Model physics with compressed or partially compressed spectra. © 2012 Elsevier B.V.

Mukhopadhyay S.K.,University of Calcutta | Mitra M.,University of Calcutta | Mitra S.,Netaji Nagar Day College
2011 International Conference on Computer, Communication and Electrical Technology, ICCCET 2011 | Year: 2011

Efficient and reliable electrocardiogram (ECG) compression system can increase the processing speed of real-time ECG transmission as well as reduce the amount of data storage in long-term ECG recording. In the present paper, a software based effective ECG data compression algorithm is proposed. The whole algorithm is written in C- platform. The algorithm is tested on various ECG data of all the 12 leads taken from PTB Diagnostic ECG Database (PTB-DB). In this compression methodology, all the R-Peaks are detected at first by differentiation technique and QRS regions are located. To achieve a strict lossless compression in QRS regions and a tolerable lossy compression in rest of the signal, two different compression algorithms have developed. In lossless compression method a difference array has been generated from the corresponding input ECG "Voltage" values and then those are multiplied by a considerably large integer number to convert them into integer. In the next step, theses integer numbers are grouped in both forward and reverse direction maintaining some logical criteria. Then all the grouped numbers along with sign bit and other necessary information (position of critical numbers, forward/reverse grouping etc.) are converted into their corresponding ASCII characters. Whereas in lossy area, first of all, the sampling frequency of the original ECG signal is reduced to one half and then, only the "Voltage" values are gathered from the corresponding input ECG data and those are amplified and grouped only in forward direction. Then all the grouped numbers along with sign bit and other necessary information are converted into their corresponding ASCII characters. It is observed that this proposed algorithm can reduce the file size significantly. The data reconstruction algorithm has also been developed using the reversed logic and it is seen that data is reconstructed preserving the significant ECG signal morphology. © 2011 IEEE.

Chakraborti M.,Indian Association for The Cultivation of Science | Chattopadhyay U.,Indian Association for The Cultivation of Science | Choudhury A.,Indian Institute of Science | Datta A.,University of Calcutta | Poddar S.,Netaji Nagar Day College
Journal of High Energy Physics | Year: 2014

Using the chargino-neutralino and slepton search results from the LHC in conjunction with the WMAP/PLANCK and (g - 2) μ data, we constrain several generic pMSSM models with decoupled strongly interacting sparticles, heavier Higgs bosons and characterized by different hierarchies among the EW sparticles. We find that some of them are already under pressure and this number increases if bounds from direct detection experiments like LUX are taken into account, keeping in mind the associated uncertainties. The XENON1T experiment is likely to scrutinize the remaining models closely. Analysing models with heavy squarks, a light gluino along with widely different EW sectors, we show that the limits on mg ̃ are not likely to be below 1.1 TeV, if a multichannel analysis of the LHC data is performed. Using this light gluino scenario we further illustrate that in future LHC experiments the models with different EW sectors can be distinguished from each other by the relative sizes of the n-leptons + m-jets + [InlineMediaObject not available: see fulltext.] T signals for different choices of n. © 2014 The Author(s).

Bose R.,University of Calcutta | Datta A.,University of Calcutta | Kundu A.,University of Calcutta | Poddar S.,Netaji Nagar Day College
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We consider a model of neutrino mass based on R-parity-violating supersymmetry, with three μi, relevant for bilinear R-parity-violating terms, and three λijk', relevant for the trilinear terms. The present neutrino data, after a precise determination of the mixing angle θ13, severely constrain such models. We make a thorough study of one such class of models that may have interesting signatures at the upgraded LHC. In this class of models, the relevant trilinear couplings are of the form λi33′, so if the lighter stop squark t̃1 is the lightest supersymmetric particle, it will decay only through these couplings, giving rise to events with isolated hard leptons and jets. Even when t̃1 is the next-to-lightest supersymmetric particle, it can decay via the tiny λ' couplings allowed by the neutrino data, although it may face stiff competition from some R-parity-conserving decay modes. Using a simple Pythia based simulation, we find that in both the cases the signal consisting of a pair of oppositely charged leptons (ee, μμ or eμ) plus jets may be observable at the upgraded LHC experiments for a reasonable range of the t̃1 mass. © 2014 American Physical Society.

Bhattacharya D.,Jadavpur University | Santra C.R.,Netaji Nagar Day College | Ghosh A.N.,Indian National Institute of Cholera and Enteric Diseases | Karmakar P.,Jadavpur University
Journal of Biomedical Nanotechnology | Year: 2014

The cytotoxic and genotoxic potential of rod and spherical zinc oxide nanoparticles (ZnO NPs) were evaluated on human peripheral blood mononuclear cells (PBMCs). Their sizes and shapes were determined by Transmission electron microscopy (TEM) and physical characterizations were done by X-ray diffraction (XRD) and Dynamic light scattering (DLS). The cytotoxic potential of rod ZnO NPs was greater than spherical ZnO NPs when applied to PBMCs and was limited to the proliferative lymphocytes. Rod ZnO NPs produced more reactive oxygen species (ROS) compared to spherical ones. Additionally rod ZnO NPs induced significant DNA damage to PBMCs as revealed by cytokinesis block micronucleus (CBMN) assay and comet assay. On the other hand UV absorption property was enhanced in case of spherical ZnO NPs compared to rod ZnO NPs. Thus, present study implicates the shape dependent differential application of ZnO NPs in our daily life. Copyright © 2014 American Scientific Publishers All rights reserved.

Garain S.,Jadavpur University | Jana S.,Jadavpur University | Jana S.,Netaji Nagar Day College | Sinha T.K.,Indian Institute of Technology Kharagpur | Mandal D.,Jadavpur University
ACS Applied Materials and Interfaces | Year: 2016

We report an efficient, low-cost in situ poled fabrication strategy to construct a large area, highly sensitive, flexible pressure sensor by electrospun Ce3+ doped PVDF/graphene composite nanofibers. The entire device fabrication process is scalable and enabling to large-area integration. It can able to detect imparting pressure as low as 2 Pa with high level of sensitivity. Furthermore, Ce3+-doped PVDF/graphene nanofiber based ultrasensitive pressure sensors can also be used as an effective nanogenerator as it generating an output voltage of 11 V with a current density ∼6 nA/cm2 upon repetitive application of mechanical stress that could lit up 10 blue light emitting diodes (LEDs) instantaneously. Furthermore, to use it in environmental random vibrations (such as wind flow, water fall, transportation of vehicles, etc.), nanogenerator is integrated with musical vibration that exhibits to power up three blue LEDs instantly that promises as an ultrasensitive acoustic nanogenerator (ANG). The superior sensing properties in conjunction with mechanical flexibility, integrability, and robustness of nanofibers enabled real-time monitoring of sound waves as well as detection of different type of musical vibrations. Thus, ANG promises to use as an ultrasensitive pressure sensor, mechanical energy harvester, and effective power source for portable electronic and wearable devices. © 2016 American Chemical Society.

Ankamwar B.,University of Pune | Kamble V.,University of Pune | Sur U.K.,University of Pune | Santra C.,Netaji Nagar Day College
Applied Surface Science | Year: 2016

The development of eco-friendly and cost-effective synthetic protocol for the preparation of nanomaterials, especially metal nanoparticles is an emerging area of research in nanotechnology. These metal nanoparticles, especially silver can play a crucial role in various catalytic reactions. The biosynthesized silver nanoparticles described here was very stable up to 6 months and can be further exploited as an effective catalyst in the chemical reduction of 4-nitrophenol to 4-aminophenol. The silver nanoparticles were utilized as an efficient surface-enhanced Raman scattering (SERS) active substrate using Rhodamine 6G as Raman probe molecule. We have also carried out systematic comparative studies on the catalytic efficiency of both silver and gold nanoparticles using UV-vis spectra to monitor the above reaction spectrophotometrically. We find that the reaction follows pseudo-first order kinetics and the catalytic activity can be explained by a simple model based on Langmuir-Hinshelwood mechanism for heterogeneous catalysis. We also find that silver nanoparticles are more efficient as a catalyst compare to gold nanoparticles in the reduction of 4-nitrophenol to 4-aminophenol, which can be explained by the morphology of the nanoparticles as determined by transmission electron microscopy. © 2016 Elsevier B.V. All rights reserved.

Bhattacharyya N.,Indian Institute of Science | Datta A.,Indian Institute of Science | Poddar S.,Netaji Nagar Day College
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

We have analyzed the early LHC signatures of the minimal supergravity (mSUGRA) model. Our emphasis is on the 7-TeV run corresponding to an integrated luminosity of ∼1.0fb-1 although we have also discussed briefly the prospects at LHC-10 TeV. We focus on the parameter space yielding relatively light squark and gluinos consistent with the dark matter relic density data and the LEP bounds on the lightest Higgs scalar mass. This parameter space is only allowed for nonvanishing trilinear soft breaking term A0. A significant region of the parameter space with large to moderate negative values of A0 consistent with the stability of the scalar potential and relic density production via neutralino annihilation and/or neutralino-stau coannihilation yields observable signal via the jets+missing transverse energy channel. The one lepton+jets+missing energy signal is also viable over a smaller but nontrivial parameter space. The ratio of the size of the two signals-free from theoretical uncertainties-may distinguish between different relic density generating mechanisms. With efficient τ-tagging facilities at 7 TeV, the discriminating power may increase significantly. We also comment on other dark matter relic density allowed mSUGRA scenarios and variants thereof in the context of LHC-7 TeV. © 2010 The American Physical Society.

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