1.
Title : B to D(D*) Form Factors in a Bethe-Salpeter Model.
Author: A. Abd-El Hady, A. Datta, K.S.Gupta and J.P.Vary
Ref-no: SINP-TNP/96-08, hep-ph/9605397
2.
Title: Renormalization Group Approach to Effective Hamiltonians.
Author: T.J. Fields, K.S. Gupta and J.P.Vary
Ref-no: SINP-TNP/96-13
Jour-ref: Mod. Phys. Lett. A11, 2233 (1996).
3.
Title: Non-relativistic Model for the Semileptonic Lambda_b to Lambda_c Decay.
Author: D. Chakraverty, T. De, B. Dutta-Roy and K.S.Gupta
Ref-no: SINP_TNP/96-19, hep-ph/9612369
4.
Title: Quantum integrability of nonultralocal models
through Baxterization of quantized braided algebra.
Author: L. Hlavaty and Anjan Kundu
Comments: Int. J. Mod. Phys. A 11 (1996) 2143-65
5.
Title: Exact Bethe ansatz solution of nonultralocal quantum mKdV model
Author: Anjan Kundu
Comments: Mod. Phys. Lett. A10 (1996) 2955-66
6.
Title: Generation of Integrable Quantum Nonultralocal Models
through Braided Yang-Baxter Equation
Author: Anjan Kundu
Comments: Proc. of Int. Conf. on Problems in QCD (Alushta, 1996)
hep-th/9607142 , SINP-TNP 96-12 (6 pages)
7.
Title: Quantum Integrable Systems: Construction, Solution, Algebraic Aspect
Author: Anjan Kundu
Comments: hep-th/9612046, SINP-TNP 96-18 (165 pages, 19 figures)
8.
AN INTRODUCTION TO LIGHT FRONT DYNAMICS FOR PEDESTRIANS.
By A. Harindranath (Saha Inst.). HEPPH-9612244, May 1996. 36pp.
Lectures given at International School on Light-Front Quantization and
Non-Perturbative QCD (To be followed by the Workshop 3-14 Jun 1996),
Ames, IA, 6 May - 2 Jun 1996.
e-Print Archive: hep-ph/9612244
9.
ON THE MATRIX ELEMENT OF THE TRANSVERSE COMPONENT OF BILOCAL VECTOR
CURRENT AND ITS PARTON INTERPRETATION.
By A. Harindranath (Saha Inst.), Wei-Min Zhang (Taiwan, National Tsing
Hua U.). HEPPH-9609289, Sep 1996. 7pp.
e-Print Archive: hep-ph/9609289
10.
HAMILTONIAN ANALYSIS OF THE DEEP INELASTIC STRUCTURE FUNCTION.
By A. Harindranath (Iowa State U.), Rajen Kundu (Saha Inst.).
HEPPH-9606433, May 1996. 20pp.
e-Print Archive: hep-ph/9606433
11.
THE TRANSVERSE POLARIZED STRUCTURE FUNCTION IN DIS AND CHIRAL
SYMMETRY BREAKING IN QCD.
By Wei-Min Zhang, A. Harindranath (IITAP, Ames). HEPPH-9606347, June
1996. 13pp.
e-Print Archive: hep-ph/9606347
12.
COMMENT ON EXTREME STATE OF CHARGED BLACK HOLE IN THE GRAND
CANONICAL ENSEMBLE.
By A. Ghosh, P. Mitra (Saha Inst.)
Journ. Ref.: Phys. Rev. Letters, Vol. 77, 4848 (1996).
13.
UNDERSTANDING THE AREA PROPOSAL FOR EXTREMAL BLACK HOLE ENTROPY.
By A. Ghosh, P. Mitra (Saha Inst.). SINP-TNP-96-14, Sep
1996. 5pp.
e-Print Archive: hep-th/9609006
Journ. Ref.: to appear in Phys. Rev. Letters (1997)
14.
QED IN TWO-DIMENSIONAL CURVED BACKGROUNDS.
By Amit Ghosh (Saha Inst.). SINP-TNP-96-06, Apr 1996.
31pp.
e-Print Archive: hep-th/9604056
15.
ENTROPY OF EXTREMAL DYONIC BLACK HOLES.
By A. Ghosh, P. Mitra (Saha Inst.). SINP-TNP-96-02, Feb
1996. 7pp.
e-Print Archive: hep-th/9602057
Journ. Ref.: Mod. Phys. Letters, A11 (1996) 2933
16.
GENERAL FORM OF THERMODYNAMIC ENTROPY OF BLACk HOLES.
By A. Ghosh, P. Mitra (Saha Inst.)
Journ. Ref.: Mod. Phys. Letters, vol. A11, 1231 (1996).
17.
MULTIDIMENSIONAL ISOTROPIC AND ANISOTROPIC Q-OSCILLATOR MODELS.
By A. Ghosh, P. Mitra and A. Kundu (Saha Inst.)
Journ. Ref.: J. Phys., vol. A29, 115 (1996).
18.
Title: The nonconfining Schwinger model
Published in: Ann. Phys. 249 (1996) 34
Authors: A. Rahaman and P. Mitra
19.
Title: Nonmanifest Lorentz invariance in vector coupled model
Published in: MPLA 11 (1996) 2153
Authors: A. Rahaman and P. Mitra
20.
Title: Refined Thomas-Fermi description of hot nuclei
Published in: Phys. Rev. C53(1996)780
Authors: J.N.De, N.Rudra, Subrata Pal and S.K.Samaddar
21.
Title: The effect of flow on nuclear multifragmentation in a quantum
statistical model
Published in: Nucl. Phys. A 608(1996)49
Authors: Subrata Pal, S.K.Samaddar and J.N.De
22.
Title: Pion production in proton-proton collisions in a covariant one-boson-
exchange model
Authors: A. Engel, R. Shyam, U. Mosel and A.K. Dutt-Mazumder
Published in Nuc. Phys. A603 (1996)387-414
23.
Title: Energy and momentum distribution of fragments in reactions induced
by one neutron halo nucleus ^11Be
Authors: P. Banerjee and R. Shyam
Published in J. Phys.G: Nuc. Part. Phys. 22 (1996) L79-L86
24.
Title: Astrophysical S-factor of the ^7Be(p,gamma)^8B reaction from
Coulomb dissociation of ^8B.
Authors: R. Shyam, I.J. Thompson and A.K. Dutt-Mazumder
Published in Phys. Lett. B 371 (1996) 1-6
25.
Title: NN --> NN PI reaction near threshold in a covariant one-boson-exchange
model.
Authors: R. Shyam, and U. Mosel
Report No. LANL nucl-th/9611013 Phys. Rev. Lett. (Submitted)
26.
Title: E2 component in subCoulomb breakup of ^8B.
Authors: R. Shyam and I.J. Thompson
Comments : LANL preprint nucl-th/9611054 Phys. Lett. B (Submitted)
27.
Title: Dilepton yield in heavy ion collisions with Bose enhancement of
decay widths.
Author: Abhee K. Dutt-Mazumder (Saha Inst.), Jan-e Alam (Calcutta, VECC),
Binayak Dutta-Roy (Saha Inst.), Bikash Sinha
P-Print: SINP-TNP-96-15, Oct 1996. 13pp.
Jour-ref: Phys. Lett. B (in press)
e-Print : nucl-th/9612005
28.
Title : Matter induced rho - omega mixing.
Author : Abhee K. Dutt-Mazumder, Binayak Dutta-Roy (Saha Inst.), Anirban
Kundu (Tata Inst.).
P-print : SINP-TNP-96-07, May 1996. 10pp.
Jour-ref: Phys. Lett. B (in press)
e-Print : hep-ph/9605247
29.
Title: Vector mesons in asymmetric nuclear matter
Author: Abhee K. Dutt-Mazumder,
Jour-ref: Nucl.Phys.A 611(1996)442:
30.
Title: Symmetry breaking for rho meson in neutron matter.
Author: Abhee K. Dutt-Mazumder, Anirban Kundu, Triptesh De, Binayak
Dutta-Roy (Saha Inst.). SINP-TNP-95-23, Nov 1995. 13pp.
Jour-ref: Phys.Lett.B378:35-39,1996.
31.
Title: Tensor coupling and vector mesons in dense nuclear matter.
Author: Abhee Kanti Dutt-Mazumder, Binayak Dutta-Roy, Anirban Kundu,
Triptesh De (Saha Inst.).
P-print : SINP-TNP-95-08, Jun 1995. 14pp.
Jour-ref: Phys. Rev. C53 (1996)790
32.
Rho Mesons in Asymmetric Nuclear Matter : A
Renormalization Group Approach
A.K. Dutta Majumder,
Triptesh De, B. Dutta Roy and Anirban Kundu.
33.
Applicability of Heavy Quark Effective Theory in the
Radiative Decay B --> K g
Debrupa Chakraverty, Triptesh
De, Binayak Dutta Roy and Anirban Kundu.
34.
Spectral Distribution Studies of fp-shell Nuclei with
Modified Kuo-Brown Interaction
K. Kar, S. Sarkar, J.M.G. Gomez, V.R. Manfredi and L. Salasnich.
35.
Lattice Fermions with Chiral Symmetry
H. Banerjee and Asit K. De.
Report-no: SINP-TNP 96/10, hep-lat/9608028
Appeared in :Nucl. Phys. B (Proc. Suppl.) 53 (1997) 641
36.
Absence of a Second Order Phase Transition in lf Theory
S. Mallik and K. Mukherjee.
37.
The Nucleon Thermal loop and Rho Mediated Production of
Dileptons
A.K. Dutta Majumder, B. Dutta Roy and Bikash
Sinha.
38.
Excited States of Ge above the Neutron Emission
Threshold and Solar Neutrino Capture Rates for Ga
Detectors
K. Kar, S. Sarkar, S. Goswami and A.
Raychaudhuri.
39.
Dense Nuclear Matter in a Strong Magnetic Field
Somenath Chakrabarty, Debades Bandyopadhyay and S. Pal.
40.
Density Perturbation in Extended Inflation
S. Mallik and D. Ray Chaudhuri.
41.
Gamow-Teller strengths in fp-shell
S.Sarkar and K.Kar
Physics Letters B387 (1996)227
42.
Accelerator, reactor and atmospheric neutrino data: a three flavor oscillation
analysis
Srubabati Goswami, Kamales Kar and Amitava Raychaudhuri
Int. J. Mod. Phys. A12 781 (1997).
43.
Spectral distribution studies of fp shell nuclei with a modified Kuo-Brown
interaction
K.Kar, S.Sarkar, J.M.G.Gomez, V.R.Manfredi and L. Salasnich
Phys. Rev. C55 1260 (1997).
44.Title: $f_B$ quenched and unquenched
Authors: C. Bernard, T. Blum, Asit K. De, T. DeGrand, C. DeTar, Steven
Gottlieb, Urs M. Heller, J. Hetrick, N. Ishizuka, J. Labrenz, K.
Rummukainen, A. Soni, R. Sugar, D. Toussaint, M. Wingate
Comments: 4 pages
Report-no: Wash. U. HEP/95-31, hep-lat/9509045
Appeared in: Nucl. Phys B (Proc. Suppl.) 47 (1996) 459
45.Title:Fermions on lattice and chiral invariance
Authors: H. Banerjee, Asit K. De
Comments: 14 pages
Report-no: SNB/96/1, hep-th/9605155
1. We calculate the formfactors for the semileptonic decays of B to D and D* mesons in a Bethe-Salpeter model. We show that the model is consistent with the constraints of Heavy Quark Effective Theory (HQET) and we extract the matrix elements that represent the 1/m_Q correctionsto the form factors in HQET. We obtain$\bar\Lambda \sim 0,55$ Gev which is consistent with the QCD sum rules but higher than its estimate in the non-relativistic quark model calculations. With available data we obtain $V_{cb} = (31.9 \pm 1.4) \times 10 ^{-3}$.
2. We introduce a way of implementing renormalization within the context of the theory of effective Hamiltonians. Our renormalization scheme involves manipulations at the level of the generalized G-matrix and is independent of any specific kinematics. We show how to calculate the $\beta$ function within this context and exhibit our method using simple scale-invariant quantum mechanical systems.
3. We calculate the decay width for \Lambda_b to \Lambda_c e \bar\nu in the framework of a nonrelativistic quark model of heavy baryons where the light quarks play the role of spectators. Our calculation does not make an explicit use of the heavy quark symmetry. The branching ration for the above process as calculated here agrees reasonably well with the experimental value.
4. Formulating quantum integrability for nonultralocal models (NM) parallel to the familiar approach of inverse scattering method is a long standing problem. After reviewing our result regarding algebraic structures of ultralocal models, we look for the algebra underlying NM. We propose an universal equation represented by braided Yang-Baxter equation and able to derive all basic equations of the known models like WZWN model, nonabelian Toda chain, quantum mapping etc. As further useful application we discover new integrable quantum NM, e.g. mKdV model, anyonic model, Kundu-Eckhaus equation and derive SUSY models and reflection equation from the nonultralocal view point.
5. A lattice regularized Lax operator for the nonultralocal modified Korteweg de Vries (mKdV) equation is proposed at the quantum level with the basic operators satisfying a $q$-deformed braided algebra. Finding further the associated quantum $R$ and $Z$-matrices the exact integrability of the model is proved through the braided quantum Yang--Baxter equation, a suitably generalized equation for the nonultralocal models. Using the algebraic Bethe ansatz the eigenvalue problem of the quantum mKdV model is exactly solved and its connection with the spin-$\ha$ XXZ chain is established, facilitating the investigation of the corresponding conformal properties.
6. Formulating quantum integrability for nonultralocal models (NM) parallel to the familiar approach of inverse scattering method is a long standing problem. After reviewing our result regarding algebraic structures of ultralocal models, we look for the algebra underlying NM. We propose an universal equation represented by braided Yang-Baxter equation and able to derive all basic equations of the known models like WZWN model, nonabelian Toda chain, quantum mapping etc. As further useful application we discover new integrable quantum NM, e.g. mKdV model, anyonic model, Kundu-Eckhaus equation and derive SUSY models and reflection equation from the nonultralocal view point.
7. Various aspects of the theory of quantum integrable systems are reviewed. Basic ideas behind the construction of integrable ultralocal and nonultralocal quantum models are explored by exploiting the underlying algebraic structures related to the Yang--Baxter equations. Physical meaning of abstract mathematical notions like universal ${\cal R}$-matrix, quantized algebras, Sklyanin algebra, braided algebra, Hopf algebra etc. and the role played by them in integrable systems are highlighted. Systematic construction of quantum integrable lattice as well as field models and their exact excitation spectra are presented through examples. The coordinate and algebraic formulations of the Bethe ansatz are illustrated with comparison, along with the description of nested and functional Bethe ansatzes. The techniques for deriving quantum Hamiltonians from the Lax operators are demonstrated on concrete models. The exposition of this review is kept in a fairly elementary level with emphasis on the physical contents.
8. In these lectures we hope to provide an elementary introduction to selected topics in light-front dynamics. Starting from the study of free field theories of scalar boson, fermion, and massless vector boson, the canonical field commutators and propagators in the instant and front forms are compared and contrasted. Poincare algebra is described next where the explicit expressions for the Poincare generators of free scalar theory in terms of the field operators and Fock space operators are also given. Next, to illustrate the idea of Fock space description of bound states and to analyze some of the simple relativistic features of bound systems without getting into the wilderness of light-front renormalization, Quantum Electrodynamics in one space - one time dimensions is discussed along with the consideration of anomaly in this model. Lastly, light-front power counting is discussed. One of the consequences of light-front power counting in the simple setting of one space - one time dimensions is illustrated using massive Thirring model. Next, motivation for light-front power counting is discussed and power assignments for dynamical variables in three plus one dimensions are given. Simple examples of tree level Hamiltonians constructed by power counting are provided and finally the idea of reducing the number of free parameters in the theory by appealing to symmetries is illustrated using a tree level example in Yukawa theory.
9. In this paper we study the matrix element of the transverse component of the bilocal vector current in the context of deep inelastic scattering. BJL limit of high energy amplitudes together with light-front current algebra imply the same parton interpretation for its matrix element as that of the plus component. On the other hand, the transverse component depends explicitly on the gluon field operator in QCD, appears as "twist three" and hence its matrix element has no manifest parton interpretation. In this paper we perform calculations in light-front time-ordering perturbative QCD for a dressed quark target to order $\alpha_s$ and demonstrate that the matrix element of the transverse component of the bilocal vector current has the same parton interpretation as that of the plus component.
10. We investigate the feasibility of analyzing deep inelastic structure functions in Hamiltonian formalism by combining the light-front BJL limit of high energy amplitudes and the Fock space (multi-parton) description of hadrons. This study is motivated by some of the theoretical questions emerging from the ongoing nonperturbative/perturbative studies in light-front QCD and also by current problems in the interface of perturbative/nonperturbative QCD. In this preliminary study, we address the unpolarized structure function $F_2$. Our starting point is the expression for the quark structure function as the Fourier transform of the expectation value of the {\it good component} of a bilocal current in the target state. By expanding the target state in a set of multi-particle Fock states, the structure function is expressed as the sum of squares of multi-parton wavefunctions integrated over independent longitudinal and transverse parton momenta. Utilizing the fact that the multi-particle Fock states are connected with each other by the light-front QCD Hamiltonian, we study questions of cancellation of collinear singularities, factorization of mass singularities, and the logarithmic scaling violations in the Hamiltonian picture. In this paper the essential features of the formalism are illustrated utilizing the calculation of the structure function of a dressed quark and the evolution of the valence part of the $q {\bar q}$ bound state structure function up to order $g^2$.
11. We study the polarized structure functions in QCD. We show that $g_T$ which probes helicity flip interactions in hadrons on the light-front indeed measures the QCD dynamics of chiral symmetry breaking. The relation between chiral symmetry breaking and the observed $g_2$ data is explored.
12. It is demonstrated that the recent argument involving grand canonical ensembles claiming to show that extreme Reissner - Nordstrom black holes satisfy the area formula for entropy is unreliable.
13. Whereas the usual understanding is that the entropy of only a non-extremal black hole is given by the area of the horizon, thereare derivations of an area law for extremal black holes in string theory literature. In [15] it is explained here how such results can arise in an approach where one sums over topologies and imposes the extremality condition {\it after} quantization.
14. The two dimensional quantum electrodynamics is discussed in curved space-time, especially in the background of some black holes. We first show the existence of some new quantum mechanical solution which has interesting properties. Then for some special black holes we discuss the fermion-black hole scattering problem. The issue of confinement is intimately connected with these solutions and we also comment on this in this background. Finally, the entanglement entropy and the Hawking radiation are also discussed in this background from a slightly different viewpoint.
15. That the thermodynamic entropy for extreme charged dyonic black holes in string theory which saturate BPS-bound is proportional not to the area but to the mass or charges is demonstrated. By combining the general form of the entropy allowed by thermodynamics with recent observations in duality it is possible to fix the entropy almost completely.
16. We show that the entropy of a black hole can in general be different from a quarter of the area even at the semiclassical level.
17. Anisotropic oscillator models are considered in two and higher dimensions and their symmetries are explored. New symmetries are found for both isotropic and anisotropic cases. Applications to the spectra of triatomic molecules and superdeformed nuclei are discussed.
18. The ordinary (vector) Schwinger model is studied for a one- parameter class of regularizations commonly used in the study of the anomalous chiral Schwinger model. The theory is sensible for a range of values of the parameter and can be solved over the whole range. The fermion is unphysical only at the value which corresponds to the usual treatment.
19. A new anomalous gauge theory with vector coupling is constructed in such a way that although the starting action is not Lorentz invariant, the physical theory obtained after imposition of the constraints does satisfy Lorentz invariance.
20. Self-consistent density profiles of two-component hot nuclei in equilibrium with an external gas are calculated in the semi-classical Thomas-Fermi model with a new prescription. Thre energy functional is calculated with a momentum and density dependent finite range two-body effective interaction. The evolution of equilibrium nuclear masses as a function of temperature and densities of the external neutron and proton gas is investigated in this description. Limiting temperatures of nuclei, their life-times against neutron evaporation, temperature dependence of incompressibilities of finite nuclei and a few other observables are also studied in the present model.
21. The effect of radial collective flow on the elemental distribution in prompt nuclear multifragmentation is studied in a quantum statistical model. The production of very light fragments is seen to incrase with flow energy at all temperatures. The yield of intermediate mass fragments is however found to be enhanced with flow at relatively low temperatures, whereas it is suppressed at high temperatures.
22. Motivated by the renewed interest in studying the pion production on nuclei at few GeV incident energy, we investigate the pion production in proton-proton collisions over an energt range of 300 MeV to 2 GeV. Starting from a realistic one-boson-exchange model with parameters fitted to the amplitudes of the elasti c nucleon-nucleon scattering, we perform fully covariant calculations for the total, double and triple differential cross sections of the p(p,n pi(+))p and p(p,p pi(0))p reactions. The calculations incorporate the exchange of pi, rho, omega and sigma mesons and treat nucleon and delta isobar as intermediate states. We obtain a reasonably good agreement with the data in the entire range of beam energies. The form of the covariant delta propagator, the cut-off parameter for the pi NN and pi N delta vertex form factors and the energy dependence of the delta isobar decay width is investigated.
23. We calculate the momentum, energy and angular distribution of fragments ^11Be and a single neutron emitted in the breakup reaction induced by the one neutron halo nucleus ^11Be on a number of target nuclei at different beam energies within a direct fragmentation model. Our calculations provide a good overall description of the experimental data. The features of these reactions which underline the halo structure in ^11Be are illustrated.
24. The Coulomb dissociation method to obtain the astrophysical S-factor, S_17(0), for the ^7Be(p,gamma)^8B reaction at solar energies is investigated by by analysing the recently measured data on the breakup reaction ^208Pb(^8B,^7Be p)^208Pb at 46.5 MeV/A beam energy. Breakup cross sections corresponding to E1, E2, and M1 transitions are calculated with a theory Coulomb excitation that includes the effects of Coulomb recoil as well as relativistic retardation. The interplay of nuclear and Coulomb contributions to the breakup process is studied by performing a full quantum mechanical calculation. within the framework of the distorted wave Born approximation. In the kinematical regime of the present experiment both nuclear as well Coulomb-nuclear interference processes affect pure Coulomb cross sections very marginally. The E2 cross sections are strongly dependent on the model used to describe the structure of ^8B. The value of S_17(0) is deduced with and without E2 and M1 contributions added to the E1 cross sections as the results are discussed.
25. We calculate the cross sections for the p(p,n pi(+))p and p(p,p pi(+))p reaction for proton beam energies near threshold in a covariant one-boson-exchange model, which incorporates the exchange of pi, rho, omega and sigma mesons and treat both nucleon and delta isobar as intermediate states. The final state interactions effects have also been included. The omega and sigma meson exchange terms contribute significantly at these energies, which along with other meson exchanges, provides an excellent agreement with the data. The cross sections at beam energies below 300 MeV are almost free from the contributions of the delta isobar excitation.
26. We calculate the E1, E2 and M1 component of the angular distribution and total cross section of the ^7Be fragment emitted in the breakup reaction of ^8B on ^58Ni target at the sub-Coulomb beam energies of 25.8 MeV, within the non-relativistic theory of Coulomb excitation with three-body kinematics, using the capture cross sections of ^7Be and proton given by Kim, Park and Kim. The Calculated total breakup cross section, which has the largest contribution of the E2 component at this beam energy, is found to be very close to the upper limit of its recently measured experimental value. The data, therefore, do not rule out the relatively large E2 breakup predicted by Kim, Park and Kim. Even for the heavy target like lead the E2 component is not negligible. Thus the exctraction of the astrophysical S-factor for the radiative capture of p and ^7Be from the measurments of the Coulomb dissociation of ^8B is not free from the uncertainties of the E2 component even at the sub-Coulomb energies.
35. We propose a formulation of lattice fermions with one-sided differences that is hermitian, chirally symmetric (barring a bare mass term) and completely free of doubling. To obtain the axial anomaly in perturbation theory it was necessary to break chiral symmetry on the lattice only through a bare mass term for the physical fermion. The chiral limit may be taken once the continuum limit is reached. We comment on the role of the mass term with examples elsewhere in field theory.
39. We investigate in a relativistic Hartree theory the gross properties of cold symmetric nuclear matter and nuclear matter in beta equilibrium under the influence of strong magnetic fields. If the field strengths are above the critical values for electrons and protons, the respective phase spaces are strongly modified. This results in additional binding of the systems with distinctively softer equations of state compared to the field free cases. For magnetic field $\sim 10^{20}$ Gauss and beyond, the nuclear matter in beta equilibrium practically converts into a stable proton rich matter.
44. Results for $f_B$, $f_{B_s}$, $f_D$, $f_{D_s}$, and their ratios are
presented. High statistics quenched runs at $\beta=5.7$, $5.85$,
$6.0$, and $6.3$, plus a run still in progress at $\beta=6.52$ make
possible a preliminary extrapolation to the continuum. The data
allows good control of all systematic errors except for quenching,
although not all of the error estimates have been finalized. Results
from configurations which include effects of dynamical quarks show a
significant deviation from the quenched results and make possible a
crude estimate of the quenching error.
45. A model for lattice fermion is proposed which is, (i) free from
doublers, (ii) hermitian, and (iii) chirally invariant. The price
paid is the loss of hypercubic and reflection symmetries in the
lattice action. Thanks to the $\epsilon$-prescription, correlation
functions are free from the ill effects due to the loss of these
symmetries. In weak coupling approximation, the U(1) vector current
of a gauge theory of lattice fermion in this model is conserved in
the continuum limit. As for the U(1) axial vector current, one
obtains the ABJ anomaly if the continuum limit is implemented before
the chiral limit $m = 0$. The anomaly disappears, as in the Wilson
model, if the order of the two limits is reversed.