arXiv subjects

Mritunjay Verma

Publications and source records attributed to Mritunjay Verma.

At least 19 recordsLinked to original sources

arXiv2026

From AdS to Flat Space: Massive Spin-2 Fields

We analyze a bulk effective field theory in AdS containing a U(1)-charged massive spin-2 field coupled to a gauge field, by performing the required holographic renormalization, and computing the one and two-point functions. We then compute the renormalized bulk three-point function involving two massive spin-2 fields and one gauge field. Matching with the CFT 3-point correlator of two non-conserved spin-2 operators and a conserved current, we obtain explicit mappings between the bulk minimal and gyromagnetic couplings and the boundary OPE data. Finally, we take the flat-space limit of the momentum space CFT correlator and verify that the resulting amplitude matches the expected flat-space structure.

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arXiv2025

Carrollian Conformal Theories in Momentum Space

We consider the Carrollian conformal field theories involving scalar operators in the momentum representation. The momentum space Ward identities are explicitly solved to obtain the different branches of 2 and 3 point Carrollian conformal correlators in the momentum space. These branches are symmetry-allowed structures, characterized by different analytic structures in the Carrollian energies, and are not necessarily realized simultaneously in a single consistent theory. For specific values of the conformal dimensions, the three-point functions in momentum space exhibit logarithmic behaviour. This has no analogue in position space and instead originates from singularities in the Fourier transform relating position and momentum space correlators. We also analyze the Carrollian limit of CFT 2 and 3 point functions of scalar operators in momentum space. By taking different scalings of CFT correlators with respect to the speed of light, we obtain different branches of the Carrollian conformal correlators in the momentum space.

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arXiv2024

Massless representation of massive superfields and tree amplitudes with the pure spinor formalism

We construct the unintegrated vertex operator at the first mass level of the open superstring from the OPE of massless vertices. Using BRST cohomology manipulations, the tree amplitude of two massless and one massive state is rewritten in terms of the pure spinor superspace kinematic expression of the massless four-point amplitude at the ${\alpha^\prime}^2$ level. A generalization relating the partial $n$-point tree amplitudes with one massive state and linear combinations of the ${\alpha^\prime}^2$ corrections to n+1 massless amplitudes is found and shown to be consistent with unitarity.

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arXiv2024

Flat space spinning massive amplitudes from momentum space CFT

We discuss the flat space limit of AdS using the momentum space representation of CFT correlators. The flat space limit involves sending the AdS radius and the dimensions of operators dual to massive fields to infinity while also scaling appropriately the sources of the dual operators. In this limit, d-dimensional CFT correlators become (d+1)-dimensional scattering amplitudes. We exemplify our discussion with the computation of the flat-space limit of the CFT 3-point function of a conserved current, a non-conserved charged vector operator and its conjugate. The flat-space limit should yield the scattering amplitude of an Abelian gauge field with two massive vector fields. This scattering amplitude computes the electromagnetic form factors of the electromagnetic current in a spin-1 state, and these form factors encode the electromagnetic properties of the massive vector field (charge, magnetic moment and quadruple moment). In terms of the CFT, the flat-space limit amounts to zooming in the infrared region of the triple-K integrals that determine the 3-point function, while also scaling to infinity the order of (some of) the Bessel functions that feature in the triple-K integrals. In this limit the triple-K integral becomes proportional to the energy-preserving delta function, and the flat space limit correctly yields the corresponding flat space scattering amplitude in complete detail.

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arXiv2023

A relation between massive and massless string tree amplitudes

We uncover a relation between the scattering amplitudes of massive strings and the $α'$ expansion of the massless string amplitude at tree level. More precisely, the n-point tree amplitude of n-1 massless and one massive state is written as a linear combination of n+1 massless string amplitudes at the $α'^2$ order.

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arXiv2023

One Loop Mass Renormalization of Massive States Using Pure Spinor Formalism

As a check of the first massive integrated vertex operator in the pure spinor formalism constructed in arXiv:1802.04486, we compute the one loop 2-point function of the stable non-BPS massive states in SO(32) heterotic string theory. This allows us to compute the one loop renormalized mass of these states using the pure spinor formalism. Our results are in agreement with the corresponding results obtained by Sen using the RNS formalism. This provides an instance of the equivalence between the RNS and the pure spinor formalism for the massive states at loop level.

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arXiv2022

Momentum space CFT correlators of non-conserved spinning operators

We analyse the 3-point CFT correlators involving non-conserved spinning operators in momentum space. We derive a general expression for the conformal Ward identities defining the 3-point functions involving two generic spin $s$ non-conserved operators and a spin 1 conserved current. We give explicit expressions for the 3-point function when the two non-conserved operators have spins 1 and 2 and generic conformal dimensions. We also systematically analyse the divergences appearing in these 3-point functions when the conformal dimensions of the two non-conserved operators coincide.

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arXiv2022

IR Constraints on Gyromagnetic Ratios

In Bosonic, Heterotic and Type II theories, by employing soft theorems and string techniques, we analyze the gyromagnetic ratios of massive high spin particles coupled to Abelian gauge fields arising from the compactification of the metric and Kalb-Ramond fields. We derive a universal form for such couplings showing that mixed symmetry states of the leading Regge-trajectory, described by a Young-tableau with two rows, have a gyromagnetic ratio associated with each row.

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arXiv2021

Revisiting Higher-Spin Gyromagnetic Couplings

We analyze Bosonic, Heterotic, and Type II string theories compactified on a generic torus having constant moduli. By computing the hamiltonian giving the interaction between massive string excitations and $U(1)$ gauge fields arising from the graviton and Kalb-Ramond field upon compactification, we derive a general formula for such couplings that turns out to be universal in all these theories. We also confirm our result by explicitly evaluating the relevant string three-point amplitudes. From this expression, we determine the gyromagnetic ratio $g$ of massive string states coupled to both gauge-fields. For a generic mixed symmetry state, there is one gyromagnetic coupling associated with each row of the corresponding Young Tableau diagram. For all the states having zero Kaluza Klein or Winding charges, the value of $g$ turns out to be $1$. We also explicitly consider totally symmetric and mixed symmetry states (having two rows in the Young diagram) associated with the first Regge-trajectory and obtain their corresponding $g$ value.

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arXiv2019

Soft Theorems from Compactification

We analyze the single subleading soft graviton theorem in $(d+1)$ dimensions under compactification on $S^1$. This produces the single soft theorems for the graviton, vector and scalar fields in $d$ dimension. For the compactification of $11$-dimensional supergravity theory, this gives the soft factorization properties of the single graviton, dilaton and RR 1-form fields in type IIA string theory in ten dimensions. For the case of the soft vector field, we also explicitly check the result obtained from compactification by computing the amplitudes with external massive spin two and massless finite energy states interacting with soft vector field. The former are the Kaluza-Klein excitations of the $d+1$ dimensional metric. Describing the interaction of the KK-modes with the vector field at each level by the minimally coupled Fierz-Pauli Lagrangian, we find agreement with the results obtained from the compactification if the gyromagnetic ratio in the minimally coupled Fierz-Pauli Lagrangian is taken to be $g=1$.

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arXiv2019

Superstring Field Theory with Open and Closed Strings

We construct Lorentz invariant and gauge invariant 1PI effective action for closed and open superstrings and demonstrate that it satisfies the classical BV master equation. We also construct the quantum master action for this theory satisfying the quantum BV master equation and generalize the construction to unoriented theories. The extra free field needed for the construction of closed superstring field theory plays a crucial role in coupling the closed strings to D-branes and orientifold planes.

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arXiv2018

Integrated Massive Vertex Operator in Pure Spinor Formalism

We construct the integrated vertex operator for the first massive states of open superstrings with $(mass)^2=1/α'$ in the pure spinor formalism of the superstring theory. This vertex operator is expressed in terms of the ten dimensional $\mathcal{N}=1$ superfields describing the massive supermultiplet which appear in the unintegrated vertex operator of the same states.

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arXiv2018

Amplitudes Involving Massive States Using Pure Spinor Formalism

Same amplitudes evaluated independently using RNS and pure spinor formalism are expected to agree. While for massless states, this fact has been firmly established, for massive states such an explicit check has been lacking so far. We compute all massless-massless-massive 3-point functions in open supertrings in pure spinor formalism for the first massive states and compare them with the corresponding RNS results. We fix the normalization of the vertex operators of the massive states by comparing same set of 3-point functions for a fixed ordering in the two formalisms. Once fixed, the subsequent 3-point functions for each inequivalent ordering match exactly. This extends the explicit demonstration of equivalence of pure spinor and RNS formalism from massless states to first massive states.

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arXiv2017

Mellin Amplitudes for Fermionic Conformal Correlators

We define Mellin amplitudes for the fermion-scalar four point function and the fermion four point function. The Mellin amplitude thus defined has multiple components each associated with a tensor structure. In the case of three spacetime dimensions, we explicitly show that each component factorizes on dynamical poles onto components of the Mellin amplitudes for the corresponding three point functions. The novelty here is that for a given exchanged primary, each component of the Mellin amplitude may in general have more than one series of poles. We present a few examples of Mellin amplitudes for tree-level Witten diagrams and tree-level conformal Feynman integrals with fermionic legs, which illustrate the general properties.

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arXiv2017

Testing Subleading Multiple Soft Graviton Theorem for CHY Prescription

In arXiv:1707.06803 we derived the subleading multiple soft graviton theorem in a generic quantum theory of gravity for arbitrary number of soft external gravitons and arbitrary number of finite energy external states carrying arbitrary mass and spin. In this paper we verify this explicitly using the CHY formula for tree level scattering amplitudes of arbitrary number of gravitons in Einstein gravity. We pay special care to fix the signs of the amplitudes and resolve an apparent discrepancy between our general results in arXiv:1707.06803 and previous results on soft graviton theorem from CHY formula.

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arXiv2017

Subleading Soft Theorem for Multiple Soft Gravitons

We derive the subleading soft graviton theorem in a generic quantum theory of gravity for arbitrary number of soft external gravitons and arbitrary number of finite energy external states carrying arbitrary mass and spin. Our results are valid to all orders in perturbation theory when the number of non-compact space-time dimensions is six or more, but only for tree amplitudes for five or less non-compact space-time dimensions due to enhanced contribution to loop amplitudes from the infrared region.

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arXiv2017

Closed Superstring Field Theory and its Applications

We review recent developments in the construction of heterotic and type II string field theories and their various applications. These include systematic procedures for determining the shifts in the vacuum expectation values of fields under quantum corrections, computing renormalized masses and S-matrix of the theory around the shifted vacuum and a proof of unitarity of the S-matrix. The S-matrix computed this way is free from all divergences when there are more than 4 non-compact space-time dimensions, but suffers from the usual infrared divergences when the number of non-compact space-time dimensions is 4 or less.

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arXiv2017

Theta Expansion of First Massive Vertex Operator in Pure Spinor

We provide the covariant superspace equations that are sufficient to determine the complete $θ$ expansion of the vertex operator of the open string massive states with $(mass)^2=1/α'$ in pure spinor formalism of superstring theory. These equations get rid of the redundant degrees of freedom in superfields and are consistent with the BRST conditions derived in [1]. Further, we give the explicit $θ$ expansion of the superfields appearing in the unintegrated vertex to $O(θ^3)$. Finally, we compute the contribution to a 3-point tree amplitude with the resulting vertex operator upto $O(θ^3)$ and find its kinematic structure to be identical to the corresponding RNS computation.

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