Rajamani Narayanan
Princeton University
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Featured researches published by Rajamani Narayanan.
Nuclear Physics | 1995
Rajamani Narayanan; Herbert Neuberger
Abstract Path integration over Euclidean chiral fermions is replaced by the quantum mechanics of an auxiliary system of non-interacting fermions. Our construction avoids the no-go theorem and faithfully maintains all the known important features of chiral fermions, including the violation of some perturbative conservation laws by gauge field configurations of non-trivial topology.
Nuclear Physics | 1994
Rajamani Narayanan; Herbert Neuberger
Abstract The effective action induced by chiral fermions can be written, formally, as an overlap of two states. These states are the Fock ground states of hamiltonians for fermions in even dimensional space with opposite sign mass terms coupled to identical static vector potentials. A perturbative analysis of the overlap in the continuum framework produces the correct anomaly for abelian gauge fields in two dimensions. When a lattice transfer matrix formalism is applied in the direction perpendicular to a domain wall on which chiral fermions live a lattice version of the overlap is obtained. The real part of the overlap is nonperturbatively defined and previous work indicates that the real part of the vacuum polarization tensor in four dimensions has the correct continuum limit for a chiral theory. The phase of the overlap represents the imaginary part of the chiral action and suffers from ambiguities.
Physics Letters B | 1993
Rajamani Narayanan; Herbert Neuberger
Abstract We show that two recent independent proposals for regularizing a chiral gauge theory stem from one common trick. If the anomaly free complex representation carried by the righthanded Fermi-fields is r one constructs a vector like theory with flavored right handed fermionic matter in r+ r but with a mass matrix of the order of the cutoff and having an index equal to unity in an infinite dimensional flavor space. We present a Pauli-Villars realization of the trick that is likely to work to all orders in perturbation theory and a lattice version which is argued to produce the correct continuum leading order fermionic contribution to the vacuum polarization tensor and readied for further perturbative checks.
Physics Letters B | 1995
Rajamani Narayanan; Herbert Neuberger; Pavlos Vranas
Abstract In the continuum, the single flavor massless Schwinger model has an exact global axial U (1) symmetry in the sector of perturbative gauge fields. This symmetry is explicitly broken by gauge fields with nonzero topological charge inducing a nonzero expectation value for the bilinear ψ ψ. We show that a lattice formulation of this model, using the overlap formalism to treat the massless fermions, explicitly exhibits this phenomenon. A Monte Carlo simulation of the complete system yields the correct value of the fermion condensate and shows unambiguously that it originates from the sector of topological charge equal to unity.
Nuclear Physics | 1995
Rajamani Narayanan; Ulli Wolff
Abstract We compute the two-loop coefficient in the relation between the lattice bare coupling and the running coupling defined through the Schrodinger functional for the case of pure SU(2) gauge theory. This result is needed as one computational component to relate the latter to the MS coupling, and it allows us to implement O(a) improvement of the Schrodinger functional to two-loop order. In addition, the two-loop β-function is verified in a perturbative computation on the lattice, and the behavior of an improved bare coupling is investigated beyond one loop.
Physics Letters B | 1995
Rajamani Narayanan; Herbert Neuberger
Abstract It is shown that the lattice overlap correctly reproduces the chiral determinat on a two dimensional torus in the presence of nontrivial background Polyakov loop variables.
arXiv: High Energy Physics - Lattice | 1994
Rajamani Narayanan
Abstract I present the recent developments in a specific sub-field of chiral gauge theories on the lattice. This subfield pertais to the use of infinitely many fermi fields to describe a single chiral field. In this approach, both anomalous and anomaly free theories can be discussed in equal footing. It produces the correct anomaly in the continuum limit. It has the potential to describe fermion number violating processes in the presence of a gauge field background with non-trivial topological charge on a finite lattice.
Physics Letters B | 1995
Rajamani Narayanan; Herbert Neuberger
Abstract Golterman and Shamir [Phys. Lett. B 353 (1995) 84] falsely claim that a waveguide model modified by adding many charged bosonic spinors, in the limit of an infinite number of matter fields, becomes identical to the overlap if in the target theory every fermion appears in four copies. Their modified model would give wrong results even in the vectorial four flavor massless Schwinger model, while a dynamical simulation of this model with the overlap works correctly. In this note we pinpoint the error in the derivation of Golterman and Shamir.
arXiv: High Energy Physics - Lattice | 1994
Rajamani Narayanan; Herbert Neuberger
Abstract An expression for the lattice effective action induced by chiral fermions in any even dimensions in terms of an overlap of two states is shown to have promising properties in two and four dimensions: The correct abelian anomaly is reproduced andgauge field configurations with non-zero topological charge are completely suppressed.
Journal of Statistical Physics | 1993
Joe Kiskis; Rajamani Narayanan; Pavlos Vranas
We study the random walk representation of the two-point function in statistical mechanics models near the critical point. Using standard scaling arguments, we show that the critical exponentv describing the vanishing of the physical mass at the critical point is equal tovΘ/dw, wheredw is the Hausdorff dimension of the walk, andvΘ is the exponent describing the vanishing of the energy per unit length of the walk at the critical point. For the case ofO(N) models, we show thatv0=ϕ, whereϕ is the crossover exponent known in the context of field theory. This implies that the Hausdorff dimension of the walk isϕ/v forO(N) models.