arXiv subjects

Subhash Rajpoot

Publications and source records attributed to Subhash Rajpoot.

At least 37 records · Page 2Linked to original sources

arXiv2016

Multi-TeV flaring from blazars: Markarian 421 a case study

The TeV blazar Markarian 421 underwent multi-TeV flaring during April 2004 and simultaneously observed in x-ray and TeV energies. It was observed that the TeV outbursts had no counterparts in the lower energies, which implies that this might be an orphan flare. In the context of hadronic model, we have shown that this multi-TeV flaring can be produced due to the interaction of Fermi-accelerated protons of energy $\lesssim 168$ TeV with the background photons in the low energy tail of the synchrotron self-Compton spectrum of the blazar jet. We fit very well the flaring spectrum with this model. Based on this study, we speculate that Mrk 501 and PG 1553+113 are possible candidates for orphan flaring in the future.

astro-ph.HE↗

arXiv2015

Extended Jackiw-Pi Model and Its Supersymmetrization

We present an extended version of the so-called Jackiw-Pi (JP) model in three dimensions, and perform its supersymmetrization. Our field content has three multiplets: (i) Yang-Mills vector multiplet $(A_μ^I, λ^I)$, (ii) Parity-odd extra vector multiplet $(B_μ^I, χ^I)$, and (iii) Scalar multiplet $(C^I, ρ^I, f^I)$. The bosonic fields in these multiplets are the same as the original JP-model, except for the auxiliary field $~f^I$ which is new, while the fermions $λ^I, χ^I$ and $ρ^I$ are their super-partners. The basic difference from the original JP-model is the presence of the kinetic term for $C^I$ with its modified field-strength $H_μ^I \equiv D_μC^I + m B_μ^I$. The inclusion of the $C^I$-kinetic term is to comply with the recently-developed tensor hierarchy formulation for supersymmetrization.

hep-th↗

arXiv2015

Non-Abelian Electric-Magnetic Duality with Supersymmetry in 4D and 10D

We present electric-magnetic (Hodge) duality formulation for non-Abelian gauge groups with N=1 supersymmetry in 3+1 (4D) dimensions. Our system consists of three multiplets: (i) A super-Yang-Mills vector multiplet (YMVM) $(A_μ^I, λ^I)$, (ii) a dual vector multiplet (DVM) $(B_μ^I, χ^I)$, and (iii) an unphysical tensor multiplet (TM) $(C_{μν}{}^I, ρ^I, φ^I)$, with the index I for adjoint representation. The multiplets YMVM and DVM are dual to each other like: $G_{μν}{}^I = (1/2) ε_{μν}{}^{ρσ} F_{ρσ}{}^I$. The TM is unphysical, but still plays an important role for establishing the total consistency of the system, based on recently-developed tensor-hierarchy formulation. We also apply this technique to non-Abelian electric-magnetic duality in 9+1 (10D) dimensions. The extra bosonic auxiliary field $K_{μ_1\cdotsμ_6}$ in 10D is shown to play an important role for the closure of supersymmetry on fields.

hep-th↗

arXiv2015

Black Ring and Kerr Ellipsoid - Solitonic Configurations in Modified Finsler Gravity

We study an effective Einstein-Finsler theory on tangent Lorentz bundle constructed as a "minimal" extension of general relativity. Black ring and Kerr like ellipsoid exact solutions and soliton configurations are presented. In this endeavor the relevant metric depends not only on four dimensional spacetime coordinates and also on velocity type variables that can be interpreted as additional coordinates in the space of "extra dimensions".

gr-qc↗

arXiv2014

Metric-Independent Measures for Supersymmetric Extended Object Theories on Curved Backgrounds

For Green-Schwarz superstring sigma-model on curved backgrounds, we introduce a non-metric measure $Φ\equiv ε^{i j} ε^{I J} (\partial_i φ^I) (\partial_j φ^J)$ with two scalars $φ^I (I = 1, 2)$ used in Two Measure Theory (TMT). As in the flat-background case, the string tension $T= (2 πα' )^{-1}$ emerges as an integration constant for the A_i-field equation. This mechanism is further generalized to supermembrane theory, and to super p-brane theory, both on general curved backgrounds. This shows the universal applications of dynamical measure of TMT to general supersymmetric extended objects on general curved backgrounds.

hep-th↗

arXiv2014

Scale Symmetry Breaking From Total Derivative Densities and the Cosmological Constant Problem

The use in the action integral of totally divergent densities in generally coordinate invariant theories can lead to interesting mechanisms of spontaneous symmetry breaking of scale invariance. With dependence in the action on a metric independent density $Φ$, in $4D$ , we can define $Φ=\varepsilon^{μναβ}\partial_μA_{ναβ}$ that gives a new interesting mechanism for breaking scale symmetry in 4-D theories of gravity plus matter fields, through the $A_{ναβ}$ equations of motion which lead to an integration constant the breaks the scale symmetry, while introducing terms of the form $eG ln K$ , $e$ being the determinant of the vierbein, $G$ being the Gauss Bonnet scalar and $K$ being scalar functions of the fields transforming like $K \rightarrow cK $ (where c is a constant) under a scale transformation. Such a term is invariant only up to a total divergence and therefore leads to breaking of scale invariance due to gravitational instantons. The topological density constructed out of gauge field strengths $\varepsilon^{μναβ}F^a_{μν}F^a_{αβ}$ can be coupled to the dilaton field linearly to produce a scale invariant term up to a total divergence. The scale symmetry can be broken by Yang Mills instantons which lead to a very small vacuum energy for our Universe.

hep-th↗

arXiv2013

Detection of ultra high energy neutrinos by IceCube: Sterile neutrino scenario

The short-baseline neutrino oscillation experiments, the excess of radiation from the measurement of the cosmic microwave background radiation, the necessity of the nonbaryonic dark matter candidate and the depletion of the neutrino flux in IceCube all seem to hint at new physics beyond the standard model. An economical way to address these issues is to invoke the existence of sterile neutrinos. We present simple extensions of the standard model with additional three sterile neutrinos and discuss the corresponding PMNS like neutrino flavor mixing matrix. The noteworthy features of the sterile neutrino scenario advocated here is that the lightest one is almost degenerate with one of the active neutrinos, the second sterile has mass of order eV and the heaviest one is in the keV range. In the present scenario, the short baseline anomaly is explained through $Δm^2\sim 1\, {\rm eV^2}$, the depletion of muon neutrino flux in IceCube is explained through $Δm^2\sim 4.0\times 10^{-16}\, {\rm eV^2}$ and the dark matter problem is addressed through $Δm^2\sim 1\, {\rm keV^2}$. Our proposed mixing matrix is also compatible with the observed neutrino oscillation data. We show that the high energy muon and the tau neutrino fluxes from Gamma Ray Bursts can be depleted in IceCube by as much as 38% and 43% respectively. These substantial depletion in both muon and tau neutrino fluxes is due to their small but sizable mixing with the sterile neutrinos.

hep-ph↗

arXiv2013

N=1 Supersymmetric Non-Abelian Compensator Mechanism for Extra Vector Multiplet

We present a variant formulation of N=1 supersymmetric compensator mechanism for an arbitrary non-Abelian group in four dimensions. This formulation resembles our previous variant supersymmetric compensator mechanism in 4D. Our field content consists of the three multiplets: (i) A Non-Abelian Yang-Mills multiplet (A_μ^I, λ^I, C_{μνρ}^I), (ii) a tensor multiplet (B_{μν}^I, χ^I, φ^I) and an extra vector multiplet (K_μ^I, ρ^I, C_{μνρ}^I) with the index I for the adjoint representation of a non-Abelian gauge group. The C_{μνρ}^I is originally an auxiliary field dual to the conventional auxiliary field D^I for the extra vector multiplet. The vector K_μ^I and the tensor C_{μνρ}^I get massive, after absorbing respectively the scalar φ^I and the tensor B_{μν}^I. The superpartner fermion ρ^I acquires a Dirac mass shared with χ^I. We fix all non-trivial cubic interactions in the total lagrangian, all quadratic terms in supersymmetry transformations, and all quadratic interactions in field equations. The action invariance and the super-covariance of all field equations are confirmed up to the corresponding orders.

hep-th↗

arXiv2013

Variant N= 1 Supersymmetric Non-Abelian Proca-Stueckelberg Formalism in Four Dimensions

We present a new (variant) formulation of N=1 supersymmetric compensator mechanism for an arbitrary non-Abelian group in four dimensions. We call this `variant supersymmetric non-Abelian Proca-Stueckelberg formalism'. Our field content is economical, consisting only of the two multiplets: (i) A Non-Abelian vector multiplet (A_μ^I, λ^I, C_{μνρ}{}^I) and (ii) A compensator tensor multiplet (B_{μν}{}^I, χ^I, φ^I). The index I is for the adjoint representation of a non-Abelian gauge group. The C_{μνρ}{}^I is originally an auxiliary field Hodge-dual to the conventional auxiliary field D^I. The φ^I and B_{μν}{}^I are compensator fields absorbed respectively into the longitudinal components of A_μ^I and C_{μνρ}{}^I which become massive. After the absorption, C_{μνρ}{}^I becomes no longer auxiliary, but starts propagating as a massive scalar field. We fix all non-trivial cubic interactions in the total lagrangian, and quadratic interactions in all field equations. The superpartner fermion χ^I acquires a Dirac mass shared with the gaugino λ^I. As an independent confirmation, we give the superspace re-formulation of the component results.

hep-th↗

arXiv2012

Self-Dual Yang-Mills and Vector-Spinor Fields, Nilpotent Fermionic Symmetry, and Supersymmetric Integrable Systems

We present a system of a self-dual Yang-Mills field and a self-dual vector-spinor field with nilpotent fermionic symmetry (but not supersymmetry) in 2+2 dimensions, that generates supersymmetric integrable systems in lower dimensions. Our field content is (A_μ^I, ψ_μ^I, χ^{I J}), where I and J are the adjoint indices of arbitrary gauge group. The χ^{I J} is a Stueckelberg field for consistency. The system has local nilpotent fermionic symmetry with the algebra \{N_α^I, N_β^J \} = 0. This system generates supersymmetric Kadomtsev-Petviashvili equations in D=2+1, and supersymmetric Korteweg-de Vries equations in D=1+1 after appropriate dimensional reductions. We also show that a similar self-dual system in seven dimensions generates self-dual system in four dimensions. Based on our results we conjecture that lower-dimensional supersymmetric integral models can be generated by non-supersymmetric self-dual systems in higher dimensions only with nilpotent fermionic symmetries.

hep-th↗

arXiv2012

Self-dual non-Abelian N = 1 tensor multiplet in D = 2+ 2 dimensions

We present a self-dual non-Abelian N=1 supersymmetric tensor multiplet in D=2+2 space-time dimensions. Our system has three on-shell multiplets: (i) The usual non-Abelian Yang-Mills multiplet (A_μ^I, λ^I) (ii) A non-Abelian tensor multiplet (B_{μν}{}^I, χ^I, φ^I), and (iii) An extra compensator vector multiplet (C_μ^I, ρ^I). Here the index I is for the adjoint representation of a non-Abelian gauge group. The duality symmetry relations are G_{μνρ}{}^I = - ε_{μνρ}{}^σ\nabla_σφ^I, F_{μν}{}^I = + (1/2) ε_{μν}{}^{ρσ} F_{ρσ}{}^I, and H_{μν}{}^I = +(1/2) ε_{μν}{ρσ} H_{ρσ}{}^I, where G and H are respectively the field strengths of B and C. The usual problem with the coupling of the non-Abelian tensor is avoided by non-trivial Chern-Simons terms in the field strengths G_{μνρ}{}^I and H_{μν}{}^I. For an independent confirmation, we re-formulate the component results in superspace. As applications of embedding integrable systems, we show how the {\cal N} = 2, r = 3 and {\cal N} = 3, r = 4 flows of generalized Korteweg-de Vries equations are embedded into our system.

hep-th↗

arXiv2012

N=1 Non-Abelian Tensor Multiplet in Four Dimensions

We carry out the N=1 supersymmetrization of a physical non-Abelian tensor with non-trivial consistent couplings in four dimensions. Our system has three multiplets: (i) The usual non-Abelian vector multiplet (VM) (A_μ^I, λ^I), (ii) A non-Abelian tensor multiplet (TM) (B_{μν}{}^I, χ^I, φ^I), and (iii) A compensator vector multiplet (CVM) (C_μ^I, ρ^I). All of these multiplets are in the adjoint representation of a non-Abelian group G. Unlike topological theory, all of our fields are propagating with kinetic terms. The C_μ^I-field plays the role of a Stueckelberg compensator absorbed into the longitudinal component of B_{μν}{}^I. We give not only the component lagrangian, but also a corresponding superspace reformulation, reconfirming the total consistency of the system. The adjoint representation of the TM and CVM is further generalized to an arbitrary real representation of general SO(N) gauge group. We also couple the globally N=1 supersymmetric system to supergravity, as an additional non-trivial confirmation.

hep-th↗

arXiv2009

Implication of Compensator Field and Local Scale Invariance in the Standard Model

We introduce Weyl's scale symmetry into the standard model (SM) as a local symmetry. This necessarily introduces gravitational interactions in addition to the local scale invariance group \tilde U(1) and the SM groups SU(3) X SU(2) X U(1). The only other new ingredients are a new scalar field σand the gauge field for \tilde U(1) we call the Weylon. A noteworthy feature is that the system admits the St\" uckelberg-type compensator. The σcouples to the scalar curvature as (-ζ/2) σ^2 R, and is in turn related to a St\" uckelberg-type compensator φby σ\equiv M_P e^{-φ/M_P} with the Planck mass M_P. The particular gauge φ= 0 in the St\" uckelberg formalism corresponds to σ= M_P, and the Hilbert action is induced automatically. In this sense, our model presents yet another mechanism for breaking scale invariance at the classical level. We show that our model naturally accommodates the chaotic inflation scenario with no extra field.

hep-th↗

arXiv2009

Triality and Bagger-Lambert Theory

We present two alternative field contents for Bagger-Lambert theory, based on the triality of SO(8). The first content is (φ_{A a}, χ_{\dot A a} ; A_\m{}^{a b}), where the bosonic field φis in the 8_S of SO(8) instead of the 8_V as in the original Bagger-Lambert formulation. The second field content is (φ_{\dot A a}, χ^I{}_a ; A_\m{}^{a b}), where the bosonic field φand the fermionic field χare respectively in the 8_C and 8_V of SO(8). In both of these field contents, the bosonic potentials are positive definite, as desired. Moreover, these bosonic potentials can be unified by the triality of SO(8). To this end, we see a special constant matrix as a product of two SO(8) generators playing an important role, relating the 8_V, 8_S and 8_C of SO(8) for the triality. As an important application, we give the supersymmetry transformation rule for N=6 superconformal Chern-Simons theory with the supersymmetry parameter in the 6 of SO(6), obtained by the truncation of our first field content.

hep-th↗

arXiv2008

Lorentz-Covariant Non-Abelian Gauging of Supermembrane

We perform the Lorentz-covariant non-Abelian gauging of supermembrane (M-2 brane) action. This is a generalization of our previous work based on teleparallel formulation, in which Lorentz covariance was not manifest. We introduce the Killing supervector ξ^{A I} with the adjoint index I for a non-Abelian gauge group H. This formulation is applicable to the compactification of supermembrane from eleven dimensions into D dimensions, such as H = SO(11-D) for the compactification M_{11} \to S^{11-D} \times M_D (1\le D \le 9).

hep-th↗

arXiv2008

Standard Model and SU(5) GUT with Local Scale Invariance and the Weylon

Weyl's scale invariance is introduced as an additional local symmetry in the standard model of electroweak interactions. An inevitable consequence is the introduction of general relativity coupled to scalar fields a la Dirac and an additional vector particle we call the Weylon. Once Weyl's scale invariance is broken, the phenomenon (a) generates Newton's gravitational constant G_N and (b) triggers the conventional spontaneous symmetry breaking mechanism that results in masses for all the fermions and bosons. The scale at which Weyl's scale symmetry breaks is of order Planck mass. If right-handed neutrinos are also introduced, their absence at present energy scales is attributed to their mass which is tied to the scale where scale invariance breaks. Some implications of these ideas are noted in grand unification based on the gauge symmetry SU(5).

hep-th↗

arXiv2007

Dilaton and Second-Rank Tensor Fields as Supersymmetric Compensators

We formulate a supersymmetric theory in which both a dilaton and a second-rank tensor play roles of compensators. The basic off-shell multiplets are a linear multiplet (B_{μν}, χ, ϕ) and a vector multiplet (A_μ, ł; C_{μνρ}), where ϕand B_{\m\n} are respectively a dilaton and a second-rank tensor. The third-rank tensor C_{μνρ} in the vector multiplet is 'dual' to the conventional D-field with 0 on-shell or 1 off-shell degree of freedom. The dilaton ϕis absorbed into one longitudinal component of A_μ, making it massive. Initially, B_{μν} has 1 on-shell or 3 off-shell degrees of freedom, but it is absorbed into the longitudinal components of C_{μνρ}. Eventually, C_{μνρ} with 0 on-shell or 1 off-shell degree of freedom acquires in total 1 on-shell or 4 off-shell degrees of freedom, turning into a propagating massive field. These basic multiplets are also coupled to chiral multiplets and a supersymmetric Dirac-Born-Infeld action. Some of these results are also reformulated in superspace. The proposed mechanism may well provide a solution to the long-standing puzzle of massless dilatons and second-rank tensors in supersymmetric models inspired by string theory.

hep-th↗

arXiv2007

Comment on Papers by Foot, Kobakhidze, McDonald and Volkas Relating to Scale Invariance Symmetry

We point out that the works described by Foot et al. in arXiv:0706.1829 [hep-ph] and arXiv:0709.2750 [hep-ph] are derivatives of our work described in arXiv:hep-th/0403039, the extended version of which was published in "Standard Model and SU(5) GUT with Local Scale Invariance and the Weylon", AIP Conf. Proc. 881 (2007) pp. 82, Melville, New York, 2006. We are wondering how many motions (and publications!) they will go through before finally admitting that they have re-discovered our model, and of course, as is the usual practice these days, claiming afterwards to the world of their independent arrival at our model. Reference to our original work is long overdue.

hep-ph↗