arXiv subjects

Biswarup Mukhopadhyaya

Publications and source records attributed to Biswarup Mukhopadhyaya.

At least 163 records · Page 9Linked to original sources

arXiv2003

Slepton production from gauge boson fusion

We emphasise that charged slepton pairs produced via vector-boson fusion along with two high-mass, high-$p_T$ forward/backward jets (in two opposite hemispheres) can have a higher production cross-section for heavy slepton masses than that from conventional Drell-Yan production at a hadronic collider like the LHC. We analyse the signal and leading backgrounds in detail in the minimal supersymmetric standard model with conserved baryon and lepton numbers. Our investigation reveals that the mass reach of the vector-boson fusion channel is certainly an improvement over the scope of the Drell-Yan mode.

hep-ph↗

arXiv2003

Bhabha Scattering with Radiated Gravitons at Linear Colliders

We study the process e+- e- -> e+- e- +- missing energy at a high-energy e+- e- collider, where the missing energy arises from the radiation of Kaluza-Klein gravitons in a model with large extra dimensions. It is shown that at a high-energy linear collider, this process can not only confirm the signature of such theories but can also sometimes be comparable in effectiveness to the commonly discussed channel e+- e- -> gamma +- missing energy, especially for a large number of extra dimensions and with polarized beams. We also suggest some ways of distinguishing the signals of a graviton tower from other types of new physics signals by combining data on our suggested channel with those on the photon-graviton channel.

hep-ph↗

arXiv2003

Higgs pair production due to a radion resonance in Randall-Sundrum model: prospects at the Large Hadron Collider

We consider Higgs pair production at the Large Hadron Collider (LHC) in a Randall-Sundrum scenario containing a radion field. It is shown that the enhanced effective coupling of the radion to gluons, together with contributions from a low-lying radion pole, can provide larger event rates compared to most new physics possibilities considered so far. We present the results for both an intermediate mass Higgs and a heavy Higgs, with a detailed discussion of the background elimination procedure.

hep-ph↗

arXiv2003

Supersymmetry and neutrino mass

The existence of neutrino mass and mixing is a strong pointer towards physics beyond the standard model. An overview of the possibility of having neutrino masses in supersymmetric theories is attempted here. Some of the recent works reviewed suggest Dirac masses, whereas others include Majorana masses as well. Side by side, it is shown how R-parity violating supersymmetry opens new avenues in the neutrino sector. Reference is also made to light sterile neutrinos, nearly degenerate neutrinos and neutrinos acquiring masses from hard supersymmetry breaking terms which are suppressed by the Planck scale. In several of the cases, it is pointed out how the models that give neutrino masses and mixing have independent motivations of their own, and can be tested in accelerator experiments.

hep-ph↗

arXiv2002

Does a Randall-Sundrum scenario create the illusion of a torsion-free universe?

We consider spacetime with torsion in a Randall-Sundrum (RS) scenario where torsion, identified with the rank-2 Kalb-Ramond field, exists in the bulk together with gravity. While the interactions of both graviton and torsion in the bulk are controlled by the Planck mass, an additional exponential suppression comes for the torsion zero-mode on the visible brane. This may serve as a natural explanation of why the effect of torsion is so much weaker than that of curvature on the brane. The massive torsion modes, on the other hand, are correlated with the corresponding gravitonic modes and may be detectable in TeV-scale experiments.

hep-th↗

arXiv2002

Radiative production of invisible charginos in photon photon collision

If in a supersymmetric model, the lightest chargino is nearly degenerate with the lightest neutralino, the former can decay into the latter alongwith a soft pion (or a lepton-neutrino pair). Near degeneracy of the chargino and neutralino masses can cause the other decay products (the pion or the lepton) to be almost invisible. Photon-photon colliders offer a possibility of clean detection of such an event through a hard photon tag.

hep-ph↗

arXiv2002

Bulk torsion fields in theories with large extra dimensions

We study the consequences of spacetime torsion coexisting with gravity in the bulk in scenarios with large extra dimensions. Having linked torsion with the Kalb-Ramond antisymmetric tensor field arising in string theories, we examine its artifacts on the visible 3-brane when the extra dimensions are compactified. It is found that while torsion would have led to parity violation in a 4-dimensional framework, all parity violating effects disappear on the visible brane when the torsion originates in the bulk. However, such a scenario is found to have characteristics of its own, some of which can be phenomenologically significant.

hep-ph↗

arXiv2002

Invisible charginos and neutralinos from gauge boson fusion : a way to explore anomaly mediation ?

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. It is shown that in this way one can put by far the strongest constraint on the parameter space of a theory with anomaly mediated supersymmetry breaking (AMSB) at the LHC. In addition, scenarios where the lightest neutralinos and charginos are Higgsino-like can give signals of the above type.

hep-ph↗

arXiv2001

Signals of neutralinos and charginos from gauge boson fusion at the CERN Large Hadron Collider

We point out that interesting signals of the non-strongly interacting sector of the supersymmetric standard model arise from the production of charginos and neutralinos via vector boson fusion (VBF) at the Large Hadron Collider (LHC). In particular, if R-parity is violated, the hadronically quiet signals of charginos and neutralinos through direct production get considerably suppressed. We show that in such cases, the VBF channel can be useful in identifying this sector through clean and background-free final states.

hep-ph↗

arXiv2001

Spacetime torsion and parity violation: a gauge invariant formulation

The possibility of parity violation through spacetime torsion has been explored in a scenario containing fields with different spins. Taking the Kalb-Ramond field as the source of torsion, an explicitly parity violating $U(1)_{EM}$ gauge invariant theory has been constructed by extending the KR field with a Chern-Simons term.

hep-th↗

arXiv2001

Heavy quark production via supersymmetric interaction at a neutrino factory

We investigate b-quark production in both charged and neutral current channels through neutrino-nucleon scattering at a neutrino factory, mediated by the lepton flavour violating interactions present in a supersymmetric theory with broken R-parity. Using values of the effctive interaction strengths well below the current and projected experimental bounds, we are still able to predict markedly enhanced event rates, especially for the neutral current events which are not allowed at the lowest order in the standard model (SM). Data from neutrino factories can therefore be used to probe strengths of such interactions to considerably higher precision than what can be envisioned in other experiments.

hep-ph↗

arXiv2001

Signals of R-parity Violating Supersymmetry at a Muon Storage Ring

Neutrino oscillation signals at muon storage rings (MSR) can be mimicked by Supersymmetric (SUSY) interactions in an R-parity violating scenario. We have investigated the $τ$-appearance signals for both long-baseline and near-site experiments, and concluded that the latter is of great use in distinguishing between oscillation and SUSY effects. On the other hand, SUSY can cause a manifold increase in the event rate for wrong-sign muons at a long-baseline setting, thereby providing us with signatures of new physics.

hep-ph↗

arXiv2001

Signals of R-parity violating supersymmetry in neutrino scattering at muon storage rings

Neutrino oscillation signals at muon storage rings can be faked by supersymmetric (SUSY) interactions in an R-parity violating scenario. We investigate the $τ$-appearance signals for both long-baseline and near-site experiments, and conclude that the latter is of great use in distinguishing between oscillation and SUSY effects. On the other hand, SUSY can cause a manifold increase in the event rate for wrong-sign muons at a long-baseline setting, thereby providing us with signatures of new physics.

hep-ph↗

arXiv2001

Muon anomalous magnetic moment confronts exotic fermions and gauge bosons

We investigate the status of models containing exotic fermions or extra Z-like neutral gauge bosons in the light of the recent data on anomalous magnetic moment of muon. We find that it is possible to extract interesting bounds on the parameters characterizing such models. The bounds are particularly strong if the new flavour-changing neutral currents are axial vectorlike.

hep-ph↗

arXiv2001

New Higgs signals from vector boson fusion in R-parity violating supersymmetry

We investigate signals of the lightest neutral Higgs in an R-parity violating supersymmetric model through the vector boson fusion mechanism. Assuming that R-parity is violated through lepton number, and locating regions in the parameter space where decays of such a neutral scalar into a pair of lightest neutralinos can be significant, we proceed to calculate the event rates for final states arising from decays of the neutralinos through both $λ$-and $λ'$-type interactions. Regions of the parameter space where each of these types of interactions can lead to detectable events are identified. The possibilities where such signals can be faked by other superparticles (squarks, gluinos, charginos and neutralinos) are also investigated. It is found that over a sizable region, one can obtain distinguishable signals of an intermediate mass neutral scalar from a study of the suggested final states at the Large Hadron Collider.

hep-ph↗

arXiv2000

Tevatron Signatures of an R-parity Violating Supersymmetric Theory

We show that an R-parity violating supersymmetric scenario which can account for the atmospheric nu(mu) deficit has testable signals at the Fermilab Tevatron with upgraded energy and luminosity. The explanation of neutrino masses and maximal nu(mu)-nu(tau) oscillation in terms of bilinear R-violating terms in the superpotential associates comparable numbers of muons and tau's resulting from decays of the lightest neutralino. We show that this should lead to like-sign dimuons and ditaus with substantial rates, in a form that separates them from standard model backgrounds and other signals of supersymmetry. One here also has the possibility of completely reconstructing the lightest neutralino.

hep-ph↗

arXiv2000

Are Messages of R-parity Violating Supersymmetry Hidden within Top Quark Signals ?

In an R-parity nonconserving supersymmetric theory, the lighter stop can dominantly decay into $bμ$ and $bτ$ if R-parity breaking has to explain the neutrino mass and mixing pattern suggested by the data on atmospheric muon neutrinos. This should give rise to $dilepton+dijet$ and $single-lepton+jets$, signals resembling those of the top quark at the Fermilab Tevatron. One can thus constrain the stop parameter space using the current top search data, and similarly look for the first signals of supersymmetry at the upgraded runs of the Tevatron.

hep-ph↗

arXiv1999

Radiative decay of the lightest neutralino in an R-parity violating supersymmetric theory

In an R-parity violating supersymmetric scenario, the lightest neutralino $\tilde χ^0_1$ is no longer a stable particle. We calculate the branching ratio for the decay mode $\tilde χ^0_1 \longrightarrow νγ$ which occurs at the one-loop level. Taking into account bilinear as well as trilinear lepton number violating interactions as the sources of R-parity violation, we make a detailed scan of the parameter space, both with and without gaugino mass unification and including the constraints on the neutrino sector from the recent Superkamiokande results. This study enables one to suggest interesting experimental signals distinguishing between the two types of R-parity breaking, and also to ascertain whether such radiative decays can give rise to collider signals of the type $γγ$ + $\not {\rm E}$ from pair-produced neutralinos.

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