Gerardo Cristofano | University of Naples "Federico II" / Università di Napoli Federico II (original) (raw)

Papers by Gerardo Cristofano

Research paper thumbnail of 2D electron in a magnetic field with dissipation

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Research paper thumbnail of Superstring elastic scattering at √s≥1019 GeV: the covariant loop calculus approach

Nuclear Physics B, 1991

We study quantum gravity by considering the elastic scattering of two on-shell string ground stat... more We study quantum gravity by considering the elastic scattering of two on-shell string ground states in the large-s, fixed-t asymptotic limit. The amplitude is computed by means of the covariant loop calculus which turns out to be a powerful method in the study of such a Regge regime. The leading contribution in powers of s is shown to factorize at

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Research paper thumbnail of 2D electron in an external magnetic field in the presence of dissipation

ABSTRACT A coherent state approach is presented to analyze the behavior of a 2D electron subject ... more ABSTRACT A coherent state approach is presented to analyze the behavior of a 2D electron subject to an external magnetic field, normal to the plane, in the presence of dissipation. The phenomenon of the shrinking of the Gaussian (localization), describing the electron ground state, takes place on large time scales. Its relation with the transport properties of such a system is then analyzed.

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Research paper thumbnail of Post-Newtonian Corrections in Gravitation from Superstring Theory

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Research paper thumbnail of Superstring elastic scattering at sqrt(s)>=1019 GeV The covariant loop calculus approach

Nuclear Physics B

We study quantum gravity by considering the elastic scattering of two on-shell string ground stat... more We study quantum gravity by considering the elastic scattering of two on-shell string ground states in the large-s, fixed-t asymptotic limit. The amplitude is computed by means of the covariant loop calculus which turns out to be a powerful method in the study of such a Regge regime. The leading contribution in powers of s is shown to factorize at

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Research paper thumbnail of INFN-NA-IV 17/98 Study of the critical properties of the Quantum Hall Fluid in the framework of a dual statistical model. 1

By using Renormalization Group methods we analyze the outcome of a recent proposal of describing ... more By using Renormalization Group methods we analyze the outcome of a recent proposal of describing the Quantum Hall fluid in terms of a dual plasma which embodies dyons as effective degrees of freedom. As a consequence the physical interpretation of the two parameters of the model as the longitudinal and the Hall conductances is made clear. Parameters ’ scaling roperties allow for the determination of the critical index for the localization length after a mapping of our statistical model onto a classical percolation model. The universality of the critical properties, supported by recent experiments, is a consequence of the infinite discrete symmetry of the model SL(2, Z) (generalized duality), as noticed in a previous paper. PACS numbers: 73.40.Hm; 05.70.Fh; 11.10.Kk

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Research paper thumbnail of Mobius boundary conditions

A general CFT model for antiferromagnetic spin-1/2 ladders with

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Research paper thumbnail of INFN-Na-39/2001

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Research paper thumbnail of Dissipative 2d Electron on a Torus in External Magnetic Field:. Transport Properties and Magnetic Translations

International Journal of Modern Physics B, 1995

The effect of dissipation on the electron ground state wave function on a torus in the presence o... more The effect of dissipation on the electron ground state wave function on a torus in the presence of an external transverse magnetic field is analyzed on large time scales (t > (1)/(eta )). Its extension to the multiparticle center of the mass wave function is also given. The novel transport properties of the system are then studied by applying Laughlin

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Research paper thumbnail of Gauge Theories on the Lattice at N('c) = Infinity

The thesis is devoted to the study of the physical properties of the SU(N(,c)) Yang Mills theory ... more The thesis is devoted to the study of the physical properties of the SU(N(,c)) Yang Mills theory on the lattice at N(,c) = (INFIN). Since the lattice approach provides us with a natural framework toward a better understanding of nonperturbative phenomena, like quark confinement, we study nonperturbative physical quantities, like the string tension and the glueball mass. The first two

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Research paper thumbnail of FQHE AND JAIN’S APPROACH ON THE TORUS

International Journal of Modern Physics B, 1995

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Research paper thumbnail of 2D ELECTRON IN AN EXTERNAL MAGNETIC FIELD IN THE PRESENCE OF DISSIPATION

International Journal of Modern Physics B, 1995

A coherent state approach is presented to analyze the behavior of a 2D electron subject to an ext... more A coherent state approach is presented to analyze the behavior of a 2D electron subject to an external magnetic field, normal to the plane, in the presence of dissipation. The phenomenon of the shrinking of the Gaussian (localization), describing the electron ground state, takes place on large time scales. Its relation with the transport properties of such a system is

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Research paper thumbnail of O(N) non-linear ð-model with improved action: A strong coupling analysis

Physics Letters B, 1984

A study of the O(N) non-linear ð-model on a euclidean lattice with a Symanzik tree-level-improved... more A study of the O(N) non-linear ð-model on a euclidean lattice with a Symanzik tree-level-improved action is performed by means of strong coupling technique and the approach to the continuum for the mass and the susceptibility is analyzed. The behaviour of the dimensionless product chim2 shows a substantial improvement for N as low as four, whereas for the evaluation a

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Research paper thumbnail of Coulomb gas approach to quantum Hall effect

Physics Letters B, 1991

We show that single and multiparticle wave functions for both electrons and anyons relevant to th... more We show that single and multiparticle wave functions for both electrons and anyons relevant to the QHE can be obtained in a consistent way using Coulomb gas conformal Vertex operators. The values of the allowed charges are determined by the periodicity properties of the collective correlation functions on the torus.

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Research paper thumbnail of Coulomb Gas Vertex Operators for the Fractional Quantum Hall Effect

Progress of Theoretical Physics Supplement, 1992

A natural description of a 2D system of electrons in a transverse magnetic field is achieved by u... more A natural description of a 2D system of electrons in a transverse magnetic field is achieved by using Coulomb gas conformal vertex operators. They provide an understanding of the FQHE in terms of quantized vortex excitations with finite energy and fractional charge. Working with doubly periodic boundary conditions, we identify a specific set of vertex operators corresponding to electrons or

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Research paper thumbnail of The multiloop covariant tadpole operator and amplitudes for the bosonic string

Physics Letters B, 1988

An explicit expression is given for the covariant tadpole operator with an arbitrary number of lo... more An explicit expression is given for the covariant tadpole operator with an arbitrary number of loops, including the ghost zero mode contribution. Its integrand is recast in geometrical terms and is recognized to give the g-vacuum for the bosonic string recently discussed in the literature. By joining the g-tadpole to an N-reggeon vertex the general orientable dual amplitude with g loops is obtained.

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Research paper thumbnail of Covariant multitadpole operator and bosonization in fermionic strings

Physics Letters B, 1989

Using the bosonization technique we construct the tadpole operator for a scalar field with anomal... more Using the bosonization technique we construct the tadpole operator for a scalar field with anomaly Q on a general Riemann surface. Specifying to the case Q = 2 we derive the multitadpole operator for the fermionic string and show that it has the expected singularity cancellations.

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Research paper thumbnail of BRST invariant tadpole operator in the bosonic string

Physics Letters B, 1988

Using a BRST invariant three-reggeon vertex we construct an explicit expression for the BRST inva... more Using a BRST invariant three-reggeon vertex we construct an explicit expression for the BRST invariant planar tadpole operator for the bosonic string. Joined to an (N+1)-reggeon vertex it yields the correct expression for the one-loop N-tachyon amplitude.

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Research paper thumbnail of Tadpole operator for minimal models on arbitrary genus Riemann surfaces

Physics Letters B, 1990

... Left. B 205 (1988) 250. [ 10 ] G. Cristofano, R. Musto, F. Nicodcmi and R. Pettorino, Phys. L... more ... Left. B 205 (1988) 250. [ 10 ] G. Cristofano, R. Musto, F. Nicodcmi and R. Pettorino, Phys. Lett. B 217 (1989) 57. ... 4 (1970) 689. [ 181 G. Felder and R. Silvotti, Ziirich preprint ETH-TH/89-38 (1989) [ 19] M. Frau, A. Lerda, JG McCarthy and S. Sciuto, MIT preprint CPT-1803 (1989). ...

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Research paper thumbnail of The global phase diagram of a modular invariant two-dimensional statistical model

Physics Letters B, 2001

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Research paper thumbnail of 2D electron in a magnetic field with dissipation

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Research paper thumbnail of Superstring elastic scattering at √s≥1019 GeV: the covariant loop calculus approach

Nuclear Physics B, 1991

We study quantum gravity by considering the elastic scattering of two on-shell string ground stat... more We study quantum gravity by considering the elastic scattering of two on-shell string ground states in the large-s, fixed-t asymptotic limit. The amplitude is computed by means of the covariant loop calculus which turns out to be a powerful method in the study of such a Regge regime. The leading contribution in powers of s is shown to factorize at

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Research paper thumbnail of 2D electron in an external magnetic field in the presence of dissipation

ABSTRACT A coherent state approach is presented to analyze the behavior of a 2D electron subject ... more ABSTRACT A coherent state approach is presented to analyze the behavior of a 2D electron subject to an external magnetic field, normal to the plane, in the presence of dissipation. The phenomenon of the shrinking of the Gaussian (localization), describing the electron ground state, takes place on large time scales. Its relation with the transport properties of such a system is then analyzed.

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Research paper thumbnail of Post-Newtonian Corrections in Gravitation from Superstring Theory

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Research paper thumbnail of Superstring elastic scattering at sqrt(s)>=1019 GeV The covariant loop calculus approach

Nuclear Physics B

We study quantum gravity by considering the elastic scattering of two on-shell string ground stat... more We study quantum gravity by considering the elastic scattering of two on-shell string ground states in the large-s, fixed-t asymptotic limit. The amplitude is computed by means of the covariant loop calculus which turns out to be a powerful method in the study of such a Regge regime. The leading contribution in powers of s is shown to factorize at

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Research paper thumbnail of INFN-NA-IV 17/98 Study of the critical properties of the Quantum Hall Fluid in the framework of a dual statistical model. 1

By using Renormalization Group methods we analyze the outcome of a recent proposal of describing ... more By using Renormalization Group methods we analyze the outcome of a recent proposal of describing the Quantum Hall fluid in terms of a dual plasma which embodies dyons as effective degrees of freedom. As a consequence the physical interpretation of the two parameters of the model as the longitudinal and the Hall conductances is made clear. Parameters ’ scaling roperties allow for the determination of the critical index for the localization length after a mapping of our statistical model onto a classical percolation model. The universality of the critical properties, supported by recent experiments, is a consequence of the infinite discrete symmetry of the model SL(2, Z) (generalized duality), as noticed in a previous paper. PACS numbers: 73.40.Hm; 05.70.Fh; 11.10.Kk

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Research paper thumbnail of Mobius boundary conditions

A general CFT model for antiferromagnetic spin-1/2 ladders with

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Research paper thumbnail of INFN-Na-39/2001

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Research paper thumbnail of Dissipative 2d Electron on a Torus in External Magnetic Field:. Transport Properties and Magnetic Translations

International Journal of Modern Physics B, 1995

The effect of dissipation on the electron ground state wave function on a torus in the presence o... more The effect of dissipation on the electron ground state wave function on a torus in the presence of an external transverse magnetic field is analyzed on large time scales (t > (1)/(eta )). Its extension to the multiparticle center of the mass wave function is also given. The novel transport properties of the system are then studied by applying Laughlin

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Research paper thumbnail of Gauge Theories on the Lattice at N('c) = Infinity

The thesis is devoted to the study of the physical properties of the SU(N(,c)) Yang Mills theory ... more The thesis is devoted to the study of the physical properties of the SU(N(,c)) Yang Mills theory on the lattice at N(,c) = (INFIN). Since the lattice approach provides us with a natural framework toward a better understanding of nonperturbative phenomena, like quark confinement, we study nonperturbative physical quantities, like the string tension and the glueball mass. The first two

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Research paper thumbnail of FQHE AND JAIN’S APPROACH ON THE TORUS

International Journal of Modern Physics B, 1995

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Research paper thumbnail of 2D ELECTRON IN AN EXTERNAL MAGNETIC FIELD IN THE PRESENCE OF DISSIPATION

International Journal of Modern Physics B, 1995

A coherent state approach is presented to analyze the behavior of a 2D electron subject to an ext... more A coherent state approach is presented to analyze the behavior of a 2D electron subject to an external magnetic field, normal to the plane, in the presence of dissipation. The phenomenon of the shrinking of the Gaussian (localization), describing the electron ground state, takes place on large time scales. Its relation with the transport properties of such a system is

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Research paper thumbnail of O(N) non-linear ð-model with improved action: A strong coupling analysis

Physics Letters B, 1984

A study of the O(N) non-linear ð-model on a euclidean lattice with a Symanzik tree-level-improved... more A study of the O(N) non-linear ð-model on a euclidean lattice with a Symanzik tree-level-improved action is performed by means of strong coupling technique and the approach to the continuum for the mass and the susceptibility is analyzed. The behaviour of the dimensionless product chim2 shows a substantial improvement for N as low as four, whereas for the evaluation a

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Research paper thumbnail of Coulomb gas approach to quantum Hall effect

Physics Letters B, 1991

We show that single and multiparticle wave functions for both electrons and anyons relevant to th... more We show that single and multiparticle wave functions for both electrons and anyons relevant to the QHE can be obtained in a consistent way using Coulomb gas conformal Vertex operators. The values of the allowed charges are determined by the periodicity properties of the collective correlation functions on the torus.

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Research paper thumbnail of Coulomb Gas Vertex Operators for the Fractional Quantum Hall Effect

Progress of Theoretical Physics Supplement, 1992

A natural description of a 2D system of electrons in a transverse magnetic field is achieved by u... more A natural description of a 2D system of electrons in a transverse magnetic field is achieved by using Coulomb gas conformal vertex operators. They provide an understanding of the FQHE in terms of quantized vortex excitations with finite energy and fractional charge. Working with doubly periodic boundary conditions, we identify a specific set of vertex operators corresponding to electrons or

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Research paper thumbnail of The multiloop covariant tadpole operator and amplitudes for the bosonic string

Physics Letters B, 1988

An explicit expression is given for the covariant tadpole operator with an arbitrary number of lo... more An explicit expression is given for the covariant tadpole operator with an arbitrary number of loops, including the ghost zero mode contribution. Its integrand is recast in geometrical terms and is recognized to give the g-vacuum for the bosonic string recently discussed in the literature. By joining the g-tadpole to an N-reggeon vertex the general orientable dual amplitude with g loops is obtained.

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Research paper thumbnail of Covariant multitadpole operator and bosonization in fermionic strings

Physics Letters B, 1989

Using the bosonization technique we construct the tadpole operator for a scalar field with anomal... more Using the bosonization technique we construct the tadpole operator for a scalar field with anomaly Q on a general Riemann surface. Specifying to the case Q = 2 we derive the multitadpole operator for the fermionic string and show that it has the expected singularity cancellations.

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Research paper thumbnail of BRST invariant tadpole operator in the bosonic string

Physics Letters B, 1988

Using a BRST invariant three-reggeon vertex we construct an explicit expression for the BRST inva... more Using a BRST invariant three-reggeon vertex we construct an explicit expression for the BRST invariant planar tadpole operator for the bosonic string. Joined to an (N+1)-reggeon vertex it yields the correct expression for the one-loop N-tachyon amplitude.

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Research paper thumbnail of Tadpole operator for minimal models on arbitrary genus Riemann surfaces

Physics Letters B, 1990

... Left. B 205 (1988) 250. [ 10 ] G. Cristofano, R. Musto, F. Nicodcmi and R. Pettorino, Phys. L... more ... Left. B 205 (1988) 250. [ 10 ] G. Cristofano, R. Musto, F. Nicodcmi and R. Pettorino, Phys. Lett. B 217 (1989) 57. ... 4 (1970) 689. [ 181 G. Felder and R. Silvotti, Ziirich preprint ETH-TH/89-38 (1989) [ 19] M. Frau, A. Lerda, JG McCarthy and S. Sciuto, MIT preprint CPT-1803 (1989). ...

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Research paper thumbnail of The global phase diagram of a modular invariant two-dimensional statistical model

Physics Letters B, 2001

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