arXiv subjects

Siddharth Dwivedi

Publications and source records attributed to Siddharth Dwivedi.

26 records · Page 2Linked to original sources

arXiv2017

Reconstructing a light pseudoscalar in the Type-X Two Higgs Doublet Model

We investigate the detectability as well as reconstructibility of a light pseudoscalar particle $A$, of mass in the 50 - 60 GeV range, which is still allowed in a Type-X (lepton-specific) two-Higgs doublet scenario. Such a pseudoscalar can be pair-produced in the decay $h\to AA$ of the 125 GeV scalar $h$. The light pseudoscalar in the aforementioned range, helpful in explaining the muon anomalous magnetic moment, has not only substantial branching ratio in the $τ^+τ^-$ channel but also one of about $0.35\%$ in the $μ^+μ^-$ final state. We show how to faithfully reconstruct the $A$ mass using the $μ^+μ^-$ mode, and establish the existence of a pseudoscalar around 50 - 60 GeV, using the process $pp\to h \to AA\to μ^+μ^-\,τ^+τ^-$. This is the most reliable way of reconstructing the light $A$ mass, and is possible for an integrated luminosity of about $100~\rm{fb}^{-1}$ or less at 14 TeV, with a statistical significance that amounts to discovery.

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arXiv2017

Exploring anomalous $hb\bar b$ and $h b\bar bγ$ couplings in the context of the LHC and an $e^+e^-$ collider

In the light of the 125 GeV Higgs ($h$) discovery at the Large Hadron Collider (LHC), one of the primary goals of the LHC and possible future colliders is to understand its interactions more precisely. Here we have studied the $h$-$b$-$\bar b$-$γ$ effective interaction terms arising out of gauge invariant dimension six operators in a model independent setting, as a potential source of new physics. Their role in some detectable final states have been compared with those coming from anomalous $h$-$b$-$\bar b$ interactions. We have considered the bounds coming from the existing collider and other low energy experimental data in order to derive constraints on the potential new physics couplings and predict possible collider signals for the two different new physics scenarios in the context of 14 TeV LHC and and a future $e^+e^-$ machine. We conclude that the anomalous $h$-$b$-$\bar b$-$γ$ coupling can be probed at the LHC at 14 TeV at the 3$σ$ level with an integrated luminosity of $\sim 2000~{\rm fb}^{-1}$, which an $e^+e^-$ collider can probe at the 3$σ$ level with $\sim 12(7)~{\rm fb}^{-1}$ at $\sqrt{s}=250(500)~{\rm GeV}$. It is also found that anomalous $h$-$b$-$\bar b$ interactions, subject to the existing LHC constraints, can not compete with the rates driven by $h$-$b$-$\bar b$-$γ$ effective interactions.

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arXiv2016

Embedding and partial resolution of complex cones over Fano threefolds

This work deals with the study of embeddings of toric Calabi-Yau fourfolds which are complex cones over the smooth Fano threefolds. In particular, we focus on finding various embeddings of Fano threefolds inside other Fano threefolds and study the partial resolution of the latter in hope to find new toric dualities. We find many diagrams possible for many of these Fano threefolds, but unfortunately, none of them are consistent quiver theories. We also obtain a quiver Chern-Simons theory which matches a theory known to the literature, thus providing an alternate method of obtaining it.

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arXiv2016

Distinguishing CP-odd couplings of the Higgs boson to weak boson pairs

We consider the observable effects of CP-violating anomalous $ZZh$ interaction arising from gauge invariant dimension-6 operators at the Large Hadron Collider (LHC), with the purpose of distinguishing them from not only the standard model effects but also those of CP-even anomalous interactions of similar nature. The postulation of a gauge invariant origin makes various couplings of this kind interrelated. The updated constraints from the LHC as well as limits from neutron and electron dipole moments are used in selecting the benchmark interaction strengths. We use some asymmetry parameters that have no contribution from standard or CP-even anomalous interactions. Parton showering and detector level simulation is included to make our analysis as realistic as possible. On the whole, we conclude that gauge invariant interaction of strength $\geq 40/\rm TeV^{2} $ can be successfully isolated using integrated luminosities in the 1.5-3.0 $\rm ab^{-1}$ range.

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arXiv2015

Constraints on CP-violating gauge-Higgs operators

We consider the most general set of $SU(2) \times U(1)$ invariant CP-violating operators of dimension six, which contribute to $VVh$ interactions ($V = W, Z, γ$). Our aim is to constrain any CP-violating new physics above the electroweak scale via the effective couplings that arise when such physics is integrated out. For this purpose, we use, in turn, electroweak precision data, global fits of Higgs data at the Large Hadron Collider and the electric dipole moments of the neutron and the electron. We thus impose constraints mainly on two-parameter and three-parameter spaces. We find that the constraints from the electroweak precision data are the weakest. Among the existing Higgs search channels, considerable constraints come from the diphoton signal strength. We note that potential contribution to $h \rightarrow γZ$ may in principle be a useful constraining factor, but it can be utilized only in the high energy run. The contributions to electric dipole moments mostly lead to the strongest constraints, though somewhat fine-tuned combinations of more than one parameter with large magnitudes are allowed. We also discuss constraints on gauge boson trilinear couplings which depend on the parameters of the CP-violating operators .

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arXiv2014

Is toric duality a Seiberg-like duality in (2+1)-d ?

We show that not all $(2+1)$ dimensional toric phases are Seiberg-like duals. Particularly, we work out superconformal indices for the toric phases of Fanos ${\cal{C}}_3$, ${\cal{C}}_5$ and ${\cal{B}}_2$. We find that the indices for the two toric phases of Fano ${\cal{B}}_2$ do not match, which implies that they are not Seiberg-like duals. We also take the route of acting Seiberg-like duality transformation on toric quiver Chern-Simons theories to obtain dual quivers. We study two examples and show that Seiberg-like dual quivers are not always toric quivers.

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arXiv2013

Partial resolution of complex cones over Fano ${\cal{B}}$

In our recent paper arXiv:1108.2387, we systematized inverse algorithm to obtain quiver gauge theory living on the M2-branes probing the singularities of special kind of Calabi-Yau four-folds which were complex cones over toric Fano $\mathbb{P}^3$, ${\cal{B}}_1$, ${\cal{B}}_2$, ${\cal{B}}_3$. These quiver gauge theories cannot be given a dimer tiling presentation. We use the method of partial resolution to show that the toric data of $\mathbb{C}^4$ and Fano $\mathbb{P}^3$ can be embedded inside the toric data of Fano ${\cal{B}}$ theories. This method indirectly justfies that the two node quiver Chern-Simons theories corresponding to $\mathbb{C}^4$, Fano $\mathbb{P}^3$ and their orbifolds can be obtained by higgsing matter fields of the three node parent quiver corresponding to Fano ${\cal{B}}_1$, ${\cal{B}}_2$, ${\cal{B}}_3$, ${\cal{B}}_4$ three-folds.

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arXiv2011

Inverse algorithm and M2-brane theories

Recent paper arXiv:1103.0553 studied the quiver gauge theories on coincident $M2$ branes on a singular toric Calabi-Yau 4-folds which are complex cone over toric Fano 3-folds. There are 18 toric Fano manifolds but only 14 toric Fano were obtained from the forward algorithm. We attempt to systematize the inverse algorithm which helps in obtaining quiver gauge theories on $M2$-branes from the toric data of the Calabi-Yau 4-folds. In particular, we obtain quiver gauge theories on coincident $M2$-branes corresponding to the remaining 4 toric Fano 3-folds. We observe that these quiver gauge theories cannot be given a dimer tiling presentation.

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