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Choudhury Debajyoti | Choudhury S. | Choudhury R. K. | Choudhury T. Roy | Choudhury Sayantan | Choudhury Tirthankar Roy | Choudhury D. K. | Choudhury D. | Choudhury S. Rai | Choudhury Pabitra Pal

Somnath Suhas | Somnath Vignesh Ram

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Experimental efforts in search of 76Ge Neutrinoless Double Beta Decay

Choudhury Somnath
31 Mar 2007 hep-ph arxiv.org/abs/0704.0063

Neutrinoless double beta decay is one of the most sensitive approaches in non-accelerator particle physics to take us into a regime of physics beyond the standard model. This article is a brief review of the experiments in search of neutrinoless double beta decay from 76Ge. Following a brief introduction of the process of double beta decay from 76Ge, the results of the very first experiments IGEX and Heidelberg-Moscow which give indications of the existence of possible neutrinoless double beta decay mode has been reviewed. Then ongoing efforts to substantiate the early findings are presented and the Majorana experiment as a future experimental approach which will allow a very detailed study of the neutrinoless decay mode is discussed.

Discrete Symmetry, Neutrino Magnetic Moment and the 17 Kev Neutrino

Choudhury Debajyoti
04 Jun 1992 hep-ph arxiv.org/abs/hep-ph/9206210

The problem of generating large transition magnetic moments for nearly massless neutrinos in a truly three--generation case is discussed. A model to achieve the same by exploiting an octahedral symmetry is presented. The scheme also accomodates a radiatively generated mass of $17:keV$ for a pseudo--Dirac neutrino that decays rapidly through the Majoron channel.

Oblique electroweak corrections and triple vector boson couplings

Choudhury Debajyoti, Roy Probir, Sinha Rahul
21 Apr 1993 hep-ph arxiv.org/abs/hep-ph/9304285

We relate all $C$-- and $P$--invariant anomalous triple vector--boson couplings to the oblique electroweak parameters. LEP constraints on the latter then yield the strongest and most general simultaneous bounds to date on the former. Even if the oblique parameters assume their Standard Model values precisely, these bounds would not shrink to zero---thus underscoring the need for direct experimental probes at future colliders.

Testing Anomalous $W$ Couplings in $e^- e^-$ Collisions

Choudhury Debajyoti, Cuypers Frank
20 Dec 1993 hep-ph arxiv.org/abs/hep-ph/9312308

We analyze the influence of anomalous gauge couplings in the reaction $e^- : e^- \longrightarrow e^- : W^- : \nu_e$ at a 500 GeV linear collider. The limits imposed by this process on deviations from the standard model of electro-weak interaction, are competitive with those inferred from other high energy experiments. Furthermore, the allowed domain in the parameter space is quite different, and hence such an experiment would more than complement the other direct searches.

Signatures of an invisibly decaying Higgs particles at LHC

Choudhury Debajyoti, Roy D. P.
28 Dec 1993 hep-ph arxiv.org/abs/hep-ph/9312347

The Higgs particle can decay dominantly into an invisible channel in the Majoron models. We have explored the prospect of detecting such a Higgs particle at LHC via its associated production with a gluon, Z or W boson. While the signal/background ratio is too small for the first process, the latter two provide viable signatures for detecting such a Higgs particle.

Two-Loop Neutrino Masses and the Solar Neutrino Problem

Choudhury Debajyoti, Gandhi Raj, Gracey J. A., Mukhopadhyaya Biswarup
25 Jan 1994 hep-ph arxiv.org/abs/hep-ph/9401329

The addition of $m$ singlet right-handed neutrinos to the Standard Model leads to radiatively generated mass corrections for the $SU(2)_L $ doublet neutrinos. For those neutrinos which are massless at the tree level after this addition, this implies a small mass generated at the two-loop level via $W^{\pm}$ exchange. We calculate these mass corrections exactly by obtaining an analytic form for the general case of $n$ doublets and $m$ singlets. As a phenomenological application, we consider the $m=1$ case and examine the masses and mixings of the doublet neutrinos which arise as a result of the two-loop correction in the light of experimental data from two sources which may shed light on the question of neutrino masses. These are(a) the neutrino detectors reporting a solar neutrino deficit (and its resolution via Mikheyev-Smirnov-Wolfenstein matter oscillations), and (b) the COBE satellite data on the non-zero angular variations of the cosmic microwave background temperature (and its possible implications for hot dark matter). Within the framework of the extension considered here, which leaves the gauge group structure of the Standard Model intact, we show that it is possible for neutrinos to acquire small masses naturally, with values which are compatible with current theoretical bias and experimental data.

Model-Independent $Z'$ Limits from Electron-Electron Collisions

Choudhury D., Cuypers F., Leike A.
02 May 1994 hep-ph arxiv.org/abs/hep-ph/9404362

Model independent constraints on the mass of an extra neutral gauge boson and its couplings to charged leptons are given for the $e^-e^-$ option of a future linear collider. Analytic exclusion limits are derived in the Born approximation. The results are compared with those of the $e^+e^-$ mode. The influence of radiative corrections is discussed.

Electron-Electron Scattering as a Probe of Anomalous Gauge Couplings

Choudhury Debajyoti, Cuypers Frank
03 May 1994 hep-ph arxiv.org/abs/hep-ph/9405212

The effect of anomalous gauge couplings on polarized $e^- e^-$ scattering cross sections is examined. It turns out that different combinations of beam polarizations provide constraints that are complementary to each other and to those obtained from other experiments, such as $e^+ e^-$, $e^- \gamma$ and $\gamma \gamma$ collisions.

Test of $CP$ Violating Neutral Gauge Boson Vertices in $ e^+ e^- \rightarrow \gamma Z $

Choudhury Debajyoti, Rindani Saurabh D.
06 May 1994 hep-ph arxiv.org/abs/hep-ph/9405242

Forward-backward asymmetry in the process $e^+ e^- \rightarrow \gamma Z$ is proposed as a test for $CP$--violating anomalous $\gamma \gamma Z$ and $ \gamma Z Z$ couplings. Longitudinally polarized electron beams may be used to disentangle the effects of these couplings. We estimate possible limits that can be obtained from $e^+ e^-$ colliders at centre-of-mass energies of 200 GeV and 500 GeV.

Radiative B-decay as a test of CKM unitarity

Bhattacharyya Gautam, Branco Gustavo C., Choudhury Debajyoti
30 Jun 1994 hep-ph arxiv.org/abs/hep-ph/9406424

We point out that $R \equiv Br(b\rightarrow d \gamma)/Br(b\rightarrow s \gamma)$ is a sensitive probe of possible violation of CKM unitarity. We compute $R$ in a minimal extension of the Standard Model containing an additional isosinglet charge ($-1/3$) quark, which leads to a deviation from CKM unitarity.