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Anirban Kundu

Publications and source records attributed to Anirban Kundu.

104 records · Page 6Linked to original sources
arXiv1997

Testing Gauge-Gravitino Coupling in Gauge-Mediated Supersymmetry Breaking Through Single Photon Events

We show that the process $e^+e^- \to γ+$ missing energy, arising from the pair production of neutralinos, can probe the $γ-\tildeγ- \gravitino$ as well as the $Z-\tilde Z-\gravitino$ couplings in Gauge Mediated Supersymmetry Breaking models. This enables one to study the mutual relationship of the Goldstino couplings of the different gauginos, a feature whose testability has not been emphasized so far. The Standard Model backgrounds get suppresed with the use of a right polarized electron beam. The energy and angular distribution of the emitted photon can distinguish such models from the minimal supersymmetric theory and its variants.

hep-ph↗
arXiv1997

Gauge-Mediated Supersymmetry Breaking Signals in an Electron-Photon Collider

We show the usefulness of an $e^-γ$ collider with backscattered laser photons in unveiling the signatures of Gauge-Mediated Supersymmetry Breaking models, with a right selectron as the next LSP. We also show how the signal can be distinguished from the Standard Model background as well as from signals of minimal supersymmetry.

hep-ph↗
arXiv1996

Probing Gauge-Mediated Supersymmetry Breaking Through Polarized Electron Beams in an $e^+e^-$ Collider

Using the facts that in Gauge-Mediated Supersymmetry Breaking schemes, masses of the right and the left sfermions can differ widely, and the gravitino is the Lightest Supersymmetric Particle, we show that it is possible to obtain unambiguous signatures of such schemes in a high energy $e^+e^-$ collider if one looks at the asymmetries in the cross-sections for certain final states with left-and right-polarized beams.

hep-ph↗
arXiv1996

A general treatment of oblique parameters

A reexamination is made of one-loop oblique electroweak corrections. General definitions are given of the oblique parameters without reference to any $q^2$-expansion scheme. The old oblique parameters S,T and U are defined as differences of gauge boson vacuum polarization $Π$-functions and suffice to describe certain observable ratios on the Z-peak and the $ρ$ parameter at $q^2=0$. Regarding the new oblique parameters V,W and X, the first two are defined in terms of differences of $Π$-functions as well as the wavefunction renormalization of the corresponding weak boson, and the third in terms of the difference of differences of two $Π$-functions for $γ-Z$ mixing. Explicit expressions for measurable quantities involving all six oblique parameters are given and experimental bounds are obtained on the latter, some for the first time. A review of these constraints suggests that the linear approximation of Peskin and Takeuchi is robust.

hep-ph↗
arXiv1996

Electroweak Precision Data and a Heavy Z'

We consider the physics of an extra $U(1)$ gauge boson $Z'$, which can mix with $Z$ through intermediate fermion loops. The loop contribution due to the heavy top quark significantly affects the low-energy observables, and for $m_{Z'}>m_Z$, one can always adjust the shifts in these observables to be in the right direction suggested by experiments, when we impose the anomaly cancellation conditions for $Z'$.

hep-ph↗
arXiv1996

Matter induced rho-omega mixing

A novel mechanism for $ρ-ω$ mixing induced by neutron-proton asymmetry in nuclear matter is uncovered and the variation of the mixing angle with the extent of asymmetry is presented.

hep-ph↗
arXiv1995

Symmetry Breaking for Rho Meson in Neutron Matter

Qualitative changes in the collective excitation spectra of the $ρ$-meson triplet in neutron matter is studied, with particular emphasis on the breaking of the discrete $p\leftrightarrow n$ symmetry. The appearance of additional branches in the dispersion characteristics, the mass splitting among the charge states, the splitting between longitudinal and transverse modes of the $ρ^{\pm}$ mesons and the appearance of `island' modes (or loops) in the time-like region are some of the features that are exposed.

nucl-th↗
arXiv1995

Constraints on a General Higgs Sector from $K^0-\bar K^0$, $B_d- \bar B_d$ Mixing and the $ε$ Parameter

The scalar sector of the Standard Model is extended to include an arbitrary assortment of scalars. In the case where this assignment does not preserve $ρ=1$ at the tree-level, the departure from unity itself puts the most stringent constraint on the scalar sector, and where $ρ_{tree}=1$ is maintained, useful bounds on the parameter space of the charged Higgs mass and the doublet-nondoublet mixing angle can arise from data on $\bbbar$, $\kkbar$ mixing and the $\e$ parameter. These constraints turn out to be comparable (and in some cases, better) to those obtained from $\zbb$ data.

hep-ph↗
arXiv1995

A General Higgs Sector: Constraints and Phenomenology

We have investigated some phenomenological aspects of an $SU(2)\times U(1)$ scenario where scalars belonging to arbitrary representations of $SU(2)$ are involved in electroweak symmetry breaking. The resulting interaction terms are derived. Some constraints are obtained on the arbitrary scalar sector from the requirement of tree-level unitarity in longitudinal gauge boson scattering. We also show that, in cases where the scalars ensure $ρ=1$ at tree-level, useful restrictions on their parameter space follow from precision measurements of the $Zb\bar b$ vertex. Finally, some salient features about the production of such Higgs bosons in $e^+e^-$ collision are discussed.

hep-ph↗
arXiv1995

Tensor Coupling and Vector Mesons in Dense Nuclear Matter

The effects of magnetic interaction between vector mesons and nucleons on the propagation (mass and width) of the $ρ$-meson in particular moving through very dense nuclear matter is studied and the modifications, qualitative and quantitative, due to the relevant collective modes (zero-sound and plasma frequencies) of the medium discussed. It is shown that the $ρ$-mesons produced in high-energy nuclear collisions will be longitudinally polarized in the region of sufficiently dense nuclear matter, in the presence of such an interaction.

nucl-th↗
arXiv1994

Taming the Scalar Mass Problem with a Singlet Higgs Boson

We investigate the fine-tuning problem in the Standard Model and show that Higgs boson and top quark masses consistent with current experimental bounds cannot be obtained unless one extends the particle spectrum. A minimal extension which achieves this involves addition of a singlet real scalar and one generation of vectorlike fermions. We show that this leads to a phenomenologically viable prediction for the mass of the Standard Model Higgs boson.

hep-ph↗