Skip to main content

Hoi-lai Yu

Followers

8

Following

4

Co-authors

4

Public Views

Kevin Escalante

Christos Charalambous

Swiss Federal Institute of Technology (ETH)

Lawrence Krauss

Alessio Orlandi

Università di Bologna

Universidade da Beira Interior

Theodore Pailas

Emanuele Alesci

Interests

Uploads

Papers by Hoi-lai Yu

Black holes and Rindler superspace: Classical singularity and quantum unitarity

by Hoi-lai Yu and Chopin Soo

Physical Review D, 2007

Canonical quantization of spherically symmetric initial data appropriate to classical interior bl... more Canonical quantization of spherically symmetric initial data appropriate to classical interior black hole solutions in four dimensions is solved exactly without gauge-fixing the remaining kinematic Gauss Law constraint. The resultant mini-superspace manifold is two-dimensional, of signature (+, −), non-singular, and can be identified with the first Rindler wedge. The associated Wheeler-DeWitt equation with evolution in intrinsic superspace time is a free massive Klein-Gordon equation; and the Hamilton-Jacobi semiclassical limit of plane wave solutions can be matched to the interiors of Schwarzschild black holes. Classical black hole horizons and singularities correspond to the boundaries of the Rindler wedge. Exact wavefunctions of the Dirac equation in superspace are also considered. Precise correspondence between Schwarzschild black holes and free particle mechanics in superspace is noted. Despite the presence of classical singularities, hermiticity of the Dirac hamiltonian operator, and thus unitarity of the quantum theory, is equivalent to an appropriate boundary condition which must be satisfied by the quantum states. This boundary condition holds for quite generic quantum wavepackets of energy eigenstates, but fails for the usual Rindler fermion modes which are eigenstates with zero uncertainty in energy.

Perturbative QCD analysis of , charm yield 〈nc〉 in B decay, and τ(Λb)/τ(Bd)

Physics Letters B, 1999

Perturbative QCD analysis of B(B → Xlν), charm yield n c in B decay, and τ (Λ b )/τ (B d )

Effective gauge group of pure loop quantum gravity is : New estimate of the Immirzi parameter

Physics Letters B, 2006

We argue that the effective gauge group for pure four-dimensional loop quantum gravity(LQG) is SO... more We argue that the effective gauge group for pure four-dimensional loop quantum gravity(LQG) is SO(3) (or SO(3, C)) instead of SU (2) (or SL(2, C)). As a result, links with half-integer spins in spin network states are not realized for pure LQG, implying a modification of the spectra of area and volume operators. Our observations imply a new value of γ ≈ 0.170 for the Immirzi parameter which is obtained from matching the Bekenstein-Hawking entropy to the number of states from LQG calculations. Moreover, even if the dominant contribution to the entropy is not assumed to come from configurations with the minimum spins, the results of both pure LQG and the supersymmetric extension of LQG can be made compatible when only integer spins are realized for the former, while the latter also contains half-integer spins, together with an Immirzi parameter for the supersymmetric case which is twice the value of the SO(3) theory. We also verify that the − 1 2 coefficient of logarithmic correction to the Bekenstein-Hawking entropy formula is robust, independent of whether only integer, or also half-integer spins, are realized.

Critical exponents of new universality classes

by Hoi-lai Yu and A. Kovner

Physics Letters B, 1993

We calculate critical exponents of chiral Ising, XY and Heisenberg universality classes up to sec... more We calculate critical exponents of chiral Ising, XY and Heisenberg universality classes up to second order in 4expansion. General expressions for any number N of fermionic variables are given and compared with recent extensive l/N calculation and lattice simulations. The possibility that these new universality classes describe critical phenomena in certain 3D magnetic systems and in finite temperature phase transitions of 3 + l dimensional quantum field theories is briefly discussed.

Quasilocal energy flux of spacetime perturbation

by Hoi-lai Yu and Roh-Suan Tung

It is well known that in general relativity, because of the equivalence principle, locally we can... more It is well known that in general relativity, because of the equivalence principle, locally we cannot detect gravity and therefore any unambiguous notion of local density for conserved quantities is rendered impossible. On the other hand, the notion of total conserved quantities for spatial and null infinity are well understood. Therefore, there has been hope that one should be able to find an appropriate notion of quasilocal conserved quantities for finite spacetime domains [1].

Origin of the immirzi parameter

by Hoi-lai Yu and Roh-Suan Tung

Physical Review D, Jan 1, 2005

Dynamical renormalization group approach to the Altarelli-Parisi-Lipatov equations

Physical Review D, 2002

The Altarelli-Parisi-Lipatov equations for the parton distribution functions are rederived using ... more The Altarelli-Parisi-Lipatov equations for the parton distribution functions are rederived using the dynamical renormalization group approach to quantum kinetics. This method systematically treats the ln Q 2 corrections that arises in perturbation theory as a renormalization of the parton distribution function and unambiguously indicates that the strong coupling must be allowed to run with the scale in the evolution kernel. To leading logarithmic accuracy the evolution equation is Markovian and the logarithmic divergences in the perturbative expansion are identified with the secular divergences (terms that grow in time) that emerge in a perturbative treatment of the kinetic equations in nonequilibrium systems. The resummation of the leading logarithms by the Altarelli-Parisi-Lipatov equation is thus similar to the resummation of the leading secular terms by the Boltzmann kinetic equation.

PQCD study of the BSL and nc controversy in inclusive B decays

Physical Review D, 1998

We calculate the semileptonic branching ratio and the charm counting of inclusive B meson decays ... more We calculate the semileptonic branching ratio and the charm counting of inclusive B meson decays using the perturbative QCD formalism. For the nonleptonic decays, we employ the modified factorization theorem, in which Wilson coefficients evolve with the characteristic scales of the decay modes. It is found that the decay rate of the single-charm mode b → cūd is enhanced, and a lower B SL is obtained without increasing n c . We predict a larger b → cτν branching ratio compared to that from the conventional heavy-quarkeffective-theory based operator product expansion. Our result of the B meson lifetime is also consistent with the data.

Erratum: Heavy-quark symmetry and chiral dynamics [Phys. Rev. D 46, 1148 (1992)]

Physical Review D, 1997

In previous publications we have analyzed the strong and electromagnetic decays of heavy mesons a... more

Gauge covariance of the effective potential

Physical Review D, 1985

Straightforward, though formal, arguments are presented to establish that the effective action an... more Straightforward, though formal, arguments are presented to establish that the effective action and potential are gauge covariant at the symmetry-breaking point. We establish that in certain classes of gauge, covariant and axial gauges for Abelian theories and axial gauges for non-Abelian theories, the Nielsen equation for the effective potential can be put into closed form. Scalar electrodynamics is presented in

OBSERVABLE CONSEQUENCES OF THE STRONG COUPLING PHASE OF QED HYPOTHESIZED NEAR THE SURFACE OF LARGE-Z NUCLEI

Modern Physics Letters A, 1990

ABSTRACT We discuss observable effects of the assumption that the strong coupling phase of quantu... more ABSTRACT We discuss observable effects of the assumption that the strong coupling phase of quantum electrodynamics is realized in the surface region of heavy nuclei with large atomic number Z under a suitable external disturbance. We present some comments on anomalous peaks in electron-positron systems observed in heavy ion reactions and on effects expected in electron and positron scatterings off large-Z nuclei. We propose some experiments to test our assumption: (1) coincidence measurement of e+e- and gammagamma signals from the decays of large-Z nuclei, and (2) spectroscopy of large-Z muonic atoms.

Quantum Modifications to Gravity Waves in de Sitter Spacetime

Journal of Physics: Conference Series, 2011

Intrinsic time gravity and the Lichnerowicz–York equation

by Niall Murchadha, Chopin Soo, and Hoi-lai Yu

Classical and Quantum Gravity, 2013

We investigate the effect on the Hamiltonian structure of general relativity of choosing an intri... more We investigate the effect on the Hamiltonian structure of general relativity of choosing an intrinsic time to fix the time slicing. 3-covariance with momentum constraint is maintained, but the Hamiltonian constraint is replaced by a dynamical equation for the trace of the momentum. This reveals a very simple structure with a local reduced Hamiltonian. The theory is easily generalized; in particular, the square of the Cotton-York tensor density can be added as an extra part of the potential while at the same time maintaining the classic 2 + 2 degrees of freedom. Initial data construction is simple in the extended theory; we get a generalized Lichnerowicz-York equation with nice existence and uniqueness properties. Adding standard matter fields is quite straightforward.

Black holes and Rindler superspace: Classical singularity and quantum unitarity

by Hoi-lai Yu and Chopin Soo

Physical Review D, 2007

Canonical quantization of spherically symmetric initial data appropriate to classical interior bl... more Canonical quantization of spherically symmetric initial data appropriate to classical interior black hole solutions in four dimensions is solved exactly without gauge-fixing the remaining kinematic Gauss Law constraint. The resultant mini-superspace manifold is two-dimensional, of signature (+, −), non-singular, and can be identified with the first Rindler wedge. The associated Wheeler-DeWitt equation with evolution in intrinsic superspace time is a free massive Klein-Gordon equation; and the Hamilton-Jacobi semiclassical limit of plane wave solutions can be matched to the interiors of Schwarzschild black holes. Classical black hole horizons and singularities correspond to the boundaries of the Rindler wedge. Exact wavefunctions of the Dirac equation in superspace are also considered. Precise correspondence between Schwarzschild black holes and free particle mechanics in superspace is noted. Despite the presence of classical singularities, hermiticity of the Dirac hamiltonian operator, and thus unitarity of the quantum theory, is equivalent to an appropriate boundary condition which must be satisfied by the quantum states. This boundary condition holds for quite generic quantum wavepackets of energy eigenstates, but fails for the usual Rindler fermion modes which are eigenstates with zero uncertainty in energy.

Perturbative QCD analysis of , charm yield 〈nc〉 in B decay, and τ(Λb)/τ(Bd)

Physics Letters B, 1999

Perturbative QCD analysis of B(B → Xlν), charm yield n c in B decay, and τ (Λ b )/τ (B d )

Effective gauge group of pure loop quantum gravity is : New estimate of the Immirzi parameter

Physics Letters B, 2006

We argue that the effective gauge group for pure four-dimensional loop quantum gravity(LQG) is SO... more We argue that the effective gauge group for pure four-dimensional loop quantum gravity(LQG) is SO(3) (or SO(3, C)) instead of SU (2) (or SL(2, C)). As a result, links with half-integer spins in spin network states are not realized for pure LQG, implying a modification of the spectra of area and volume operators. Our observations imply a new value of γ ≈ 0.170 for the Immirzi parameter which is obtained from matching the Bekenstein-Hawking entropy to the number of states from LQG calculations. Moreover, even if the dominant contribution to the entropy is not assumed to come from configurations with the minimum spins, the results of both pure LQG and the supersymmetric extension of LQG can be made compatible when only integer spins are realized for the former, while the latter also contains half-integer spins, together with an Immirzi parameter for the supersymmetric case which is twice the value of the SO(3) theory. We also verify that the − 1 2 coefficient of logarithmic correction to the Bekenstein-Hawking entropy formula is robust, independent of whether only integer, or also half-integer spins, are realized.

Critical exponents of new universality classes

by Hoi-lai Yu and A. Kovner

Physics Letters B, 1993

We calculate critical exponents of chiral Ising, XY and Heisenberg universality classes up to sec... more We calculate critical exponents of chiral Ising, XY and Heisenberg universality classes up to second order in 4expansion. General expressions for any number N of fermionic variables are given and compared with recent extensive l/N calculation and lattice simulations. The possibility that these new universality classes describe critical phenomena in certain 3D magnetic systems and in finite temperature phase transitions of 3 + l dimensional quantum field theories is briefly discussed.

Quasilocal energy flux of spacetime perturbation

by Hoi-lai Yu and Roh-Suan Tung

It is well known that in general relativity, because of the equivalence principle, locally we can... more It is well known that in general relativity, because of the equivalence principle, locally we cannot detect gravity and therefore any unambiguous notion of local density for conserved quantities is rendered impossible. On the other hand, the notion of total conserved quantities for spatial and null infinity are well understood. Therefore, there has been hope that one should be able to find an appropriate notion of quasilocal conserved quantities for finite spacetime domains [1].

Origin of the immirzi parameter

by Hoi-lai Yu and Roh-Suan Tung

Physical Review D, Jan 1, 2005

Dynamical renormalization group approach to the Altarelli-Parisi-Lipatov equations

Physical Review D, 2002

The Altarelli-Parisi-Lipatov equations for the parton distribution functions are rederived using ... more The Altarelli-Parisi-Lipatov equations for the parton distribution functions are rederived using the dynamical renormalization group approach to quantum kinetics. This method systematically treats the ln Q 2 corrections that arises in perturbation theory as a renormalization of the parton distribution function and unambiguously indicates that the strong coupling must be allowed to run with the scale in the evolution kernel. To leading logarithmic accuracy the evolution equation is Markovian and the logarithmic divergences in the perturbative expansion are identified with the secular divergences (terms that grow in time) that emerge in a perturbative treatment of the kinetic equations in nonequilibrium systems. The resummation of the leading logarithms by the Altarelli-Parisi-Lipatov equation is thus similar to the resummation of the leading secular terms by the Boltzmann kinetic equation.

PQCD study of the BSL and nc controversy in inclusive B decays

Physical Review D, 1998

We calculate the semileptonic branching ratio and the charm counting of inclusive B meson decays ... more We calculate the semileptonic branching ratio and the charm counting of inclusive B meson decays using the perturbative QCD formalism. For the nonleptonic decays, we employ the modified factorization theorem, in which Wilson coefficients evolve with the characteristic scales of the decay modes. It is found that the decay rate of the single-charm mode b → cūd is enhanced, and a lower B SL is obtained without increasing n c . We predict a larger b → cτν branching ratio compared to that from the conventional heavy-quarkeffective-theory based operator product expansion. Our result of the B meson lifetime is also consistent with the data.

Erratum: Heavy-quark symmetry and chiral dynamics [Phys. Rev. D 46, 1148 (1992)]

Physical Review D, 1997

In previous publications we have analyzed the strong and electromagnetic decays of heavy mesons a... more

Gauge covariance of the effective potential

Physical Review D, 1985

Straightforward, though formal, arguments are presented to establish that the effective action an... more Straightforward, though formal, arguments are presented to establish that the effective action and potential are gauge covariant at the symmetry-breaking point. We establish that in certain classes of gauge, covariant and axial gauges for Abelian theories and axial gauges for non-Abelian theories, the Nielsen equation for the effective potential can be put into closed form. Scalar electrodynamics is presented in

OBSERVABLE CONSEQUENCES OF THE STRONG COUPLING PHASE OF QED HYPOTHESIZED NEAR THE SURFACE OF LARGE-Z NUCLEI

Modern Physics Letters A, 1990

ABSTRACT We discuss observable effects of the assumption that the strong coupling phase of quantu... more ABSTRACT We discuss observable effects of the assumption that the strong coupling phase of quantum electrodynamics is realized in the surface region of heavy nuclei with large atomic number Z under a suitable external disturbance. We present some comments on anomalous peaks in electron-positron systems observed in heavy ion reactions and on effects expected in electron and positron scatterings off large-Z nuclei. We propose some experiments to test our assumption: (1) coincidence measurement of e+e- and gammagamma signals from the decays of large-Z nuclei, and (2) spectroscopy of large-Z muonic atoms.

Quantum Modifications to Gravity Waves in de Sitter Spacetime

Journal of Physics: Conference Series, 2011

Intrinsic time gravity and the Lichnerowicz–York equation

by Niall Murchadha, Chopin Soo, and Hoi-lai Yu

Classical and Quantum Gravity, 2013

We investigate the effect on the Hamiltonian structure of general relativity of choosing an intri... more We investigate the effect on the Hamiltonian structure of general relativity of choosing an intrinsic time to fix the time slicing. 3-covariance with momentum constraint is maintained, but the Hamiltonian constraint is replaced by a dynamical equation for the trace of the momentum. This reveals a very simple structure with a local reduced Hamiltonian. The theory is easily generalized; in particular, the square of the Cotton-York tensor density can be added as an extra part of the potential while at the same time maintaining the classic 2 + 2 degrees of freedom. Initial data construction is simple in the extended theory; we get a generalized Lichnerowicz-York equation with nice existence and uniqueness properties. Adding standard matter fields is quite straightforward.