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Collins Asymmetry at Hadron Colliders

Description: We study the Collins effect in the azimuthal asymmetricdistribution of hadrons inside a high energy jet in the single transversepolarized proton proton scattering. From the detailed analysis ofone-gluon and two-gluon exchange diagrams contributions, the Collinsfunction is found the same as that in the semi-inclusive deep inelasticscattering and e+e- annihilations. The eikonal propagators in thesediagrams do not contribute to the phase needed for the Collins-typesingle spin asymmetry, and the universality is derived as a result of theWard identity. We argue that this conclusion depends on the momentum flowof the exchanged gluon and the kinematic constraints in the fragmentationprocess, and is generic and model-independent.
Date: January 17, 2008
Creator: Yuan, Feng
Partner: UNT Libraries Government Documents Department

NLO conformal symmetry in the Regge limit of QCD

Description: The authors show that a scale invariant approximation to the next-to-leading order BFKL kernel, constructed via transverse momentum diagrams, has a simple conformally invariant representation in impact parameter space. That a conformally invariant representation exists is shown first by relating the kernel directly to Feynman diagrams contributing to two photon diffractive dissociation.
Date: September 18, 1996
Creator: Coriano, C.; White, A. R. & Wuesthoff, M.
Partner: UNT Libraries Government Documents Department

A dynamical {eta}{prime} - mass from an infrared enhanced gluon exchange

Description: The pseudo-scalar flavor-singlet meson mixes with two gluons. A dimensional argument by Kogut and Susskind shows that this can screen the Goldstone pole of the chiral limit in this channel, if the gluon correlations are infrared enhanced. Using a gluon propagator as singular as {sigma}/k{sup 4} for k{sup 2} {yields} 0 we relate the screening mass to the string tension {sigma}. In the Written-Veneziano action to describe the {eta}-{eta}{prime} mixing this relation yields masses of about 810MeV for the {eta}{prime}, 430MeV for the {eta} and a mixing angle of about -30{degrees} from the phenomenological value {sigma} {approx} 0.18GeV{sup 2}. The very weak temperature dependence of the string tension should make this mechanism experimentally distinguishable from exponentially temperature dependent instanton model predictions.
Date: September 1, 1997
Creator: Smekal, L. von; Mecke, A. & Alkofer, R.
Partner: UNT Libraries Government Documents Department

One loop graviton self-energy in a locally de Sitter background

Description: The graviton tadpole has recently been computed at two loops in a locally de Sitter background. We apply intermediate results of this work to exhibit the graviton self-energy at one loop. This quantity is interesting both to check the accuracy of the first calculation and to understand the relaxation effect it reveals. In the former context we show that the self-energy obeys the appropriate Ward identity. We also show that its flat space limit agrees with the flat space result obtained by Capper in what should be the same gauge. 15 refs., 4 figs., 10 tabs.
Date: February 1996
Creator: Tsamis, N. C. & Woodard, R.P.
Partner: UNT Libraries Government Documents Department

Recent progress in irrational conformal field theory

Description: In this talk, I will review the foundations of irrational conformal field theory (ICFT), which includes rational conformal field theory as a small subspace. Highlights of the review include the Virasoro master equation, the Ward identities for the correlators of ICFT and solutions of the Ward identities. In particular, I will discuss the solutions for the correlators of the g/h coset construction and the correlators of the affine-Sugawara nests on g {contains} h{sub 1} {contains} {hor_ellipsis} {contains} h{sub n}. Finally, I will discuss the recent global solution for the correlators of all the ICFT`s in the master equation.
Date: September 1, 1993
Creator: Halpern, M. B.
Partner: UNT Libraries Government Documents Department

Derivation of general conservation laws and Ward--Takahashi identities in the functional integration method

Description: A functional integration method is applied to derive WardTakahashi identities involving the energy-momentum tensor, currents, and fields. In the process of the derivation, a variational method was introduced to derive conservation laws, in which the improved energy-momentum tensor of Callen-Coleman- -Jackiw is obtained. E stablishing the correspondence between the c-number relations obtained in the functional integration method and the q-number ones resulting from the conventional way, it is demonstrated that the two approaches of the quantum field theory give identical results for the perturbation expansion, canonical equal-time commutation relations, etc. They are, therefore, equivalent. (auth)
Date: January 1, 1972
Creator: Suura, H. & Young, B.L.
Partner: UNT Libraries Government Documents Department

t-Channel unitarity construction of small-x kernels

Description: In the leading-log approximation, the small-x behavior of parton distributions in QCD is derived from the BFKL evolution equation. The authors describe the ion as a reggeon Bethe-Salpeter equation and discuss the use of reggeon diagrams to obtain 2-2 and 2-4 reggeon interactions at O(g{sup 4}). They then outline the dispersion theory basis of multiparticle j-plane analysis and describe how a gauge theory can be studied by combining Ward identity constraints with the group structure of reggeon interactions. Gluon reggeization, the O(g{sup 2}) BFKL kernel and O(g{sup 4}) corrections to it, are derived within this formalism. They give an explicit expression for the O(g{sup 4}) forward ``parton`` kernel in terms of logarithms and evaluate the eigenvalues. A separately infra-red finite component with a holomorphically factorizable spectrum is shown to be present and conjectured to be a new leading-order partial-wave amplitude. A comparison is made with Kirschner`s discussion of O(g{sup 4}) contributions from the multi-Regge effective action.
Date: 1994-12~
Creator: Coriano, C. & White, A. R.
Partner: UNT Libraries Government Documents Department

Vacuum orientations in strong CP violation

Description: We study the QCD vacuum orientation angles in correlation with the strong CP phases. A vacuum alignment equation of the dynamical chiral symmetry breaking is derived based on the anomalous Ward identity. It is emphasized that a chiral rotation of the quark field causes a change of the vacuum orientation and a change in the definition of the light pseudoscalar generators. As an illustration of the idea, {eta} {yields} 2{pi} decays are carefully studied in different chiral frames and shown to be independent of. chiral rotations.
Date: December 1, 1991
Creator: Huang, Zheng; Viswanathan, K.S. & Wu, Dan-di
Partner: UNT Libraries Government Documents Department

Gauge theory high-energy behavior from J-plane unitarity

Description: In a non-abelian gauge theory the t-channel multiparticle unitarity equations continued in the complex j-plane can be systematically expanded around j = 1. The combination of Ward identity constraints with unitarity is sufficient to produce directly many results obtained by Regge limit leading-log and next-to-leading log momentum space calculations. The O(g{sup 2}) BFKL kernel is completely determined. O(g{sup 4}) contributions to the kernel are also determined, including the leading contribution of a new partial-wave amplitude--previously identified as a separate forward component with a holomorphically factorizable spectrum. For this amplitude the only scale ambiguity is the overall normalization and it is anticipated to be a new conformally invariant kernel. The results suggest that all conformally invariant reggeon interactions are determined by t-channel unitarity.
Date: December 31, 1995
Creator: Coriano, C. & White, A.R.
Partner: UNT Libraries Government Documents Department

Confinement, diquarks and goldstone`s theorem

Description: Determinations of the gluon propagator in the continuum and in lattice simulations are compared. A systematic truncation procedure for the quark Dyson-Schwinger and bound state Bethe-Salpeter equations is described. The procedure ensures the flavor-octet axial- vector Ward identity is satisfied order-by-order, thereby guaranteeing the preservation of Goldstone`s theorem; and identifies a mechanism that simultaneously ensures the absence of diquarks in QCD and their presence in QCD{sup N{sub c}=2}, where the color singlet diquark is the ``baryon`` of the theory.
Date: December 31, 1996
Creator: Roberts, C.D.
Partner: UNT Libraries Government Documents Department

Scale invariant 0(g{sup 4}) Lipatov kernels at non-zero momentum transfer

Description: We summarize recent work on the evaluation of the scale invariant next-to-leading order Lipatov kernel, constructed via transverse momentum diagrams. At zero momentum transfer the square of the leading-order kernel appears together with an additional component, now identified as a new partial-wave amplitude, having a separate, holomorphically factorizable, spectrum. We present a simplified expression for the full kernel at non-zero momentum transfer and give a complete analysis of its infrared properties. We also construct a nonforward extension of the new amplitude which is infrared finite and satifies Ward identity constraints. We conjecture that this new kernel has the conformal invariance properties corresponding to the holomorphic factorization of the forward spectrum.
Date: January 1996
Creator: Coriano, C.; White, A. R. & Parwani, R. R.
Partner: UNT Libraries Government Documents Department

Gauge invariance and the electromagnetic current of composite pions

Description: The Global Color-symmetry Model of QCD is extended to deal with a background electromagnetic field, and the associated conserved current is identified for the finite size {bar q}q pion modes at tree level. A well-defined truncation issued that factorizes the bilocal pion field into a local field variable and a hadronic form factor having a ladder Bethe-Salpeter content. The associated pion charge form factor is formulated. These developments are used to provide an illustration of how an effective hadronic action containing form factors may be electromagnetically coupled in a gauge invariant way that is accountable to its field substructure. In particular, the Ward-Takahashi identity for the photon vertex appropriate to the localized pion fields is seen to contain the hadronic form factors. In this context, gauge invariance of the effective hadronic action also requires recognition of the fact that the free inverse propagator for the localized pion field gauge transforms due to the substructure field content that has been absorbed into it.
Date: March 24, 1993
Creator: Frank, M. R. & Tandy, P. C.
Partner: UNT Libraries Government Documents Department

Higher-order Lipatov kernels and the QCD Pomeron

Description: Three closely related topics are covered. The derivation of O(g{sup 4}) Lipatov kernels in pure glue QCD. The significance of quarks for the physical Pomeron in QCD. The possible inter-relation of Pomeron dynamics with Electroweak symmetry breaking.
Date: August 12, 1994
Creator: White, A. R.
Partner: UNT Libraries Government Documents Department

Theoretical studies in hadronic and nuclear physics. Progress report, July 1, 1994--June 1, 1995

Description: This progress report contains 36 items of research work done by ten members of the University of Maryland Nuclear Theory Group with 21 outside collaborators from various institutions in the US, Canada, Korea and Europe. The report is in four sections, each representing major and basic areas of interest in nuclear theory. The sections are as follows: (1) hadrons in nuclei and nuclear matter; (2) hadron physics; (3) relativistic dynamics in quark, hadron and nuclear physics; (4) heavy ion dynamics and related processes.
Date: June 1, 1995
Creator: Banerjee, M.K. & Griffin, J.J.
Partner: UNT Libraries Government Documents Department

New anomaly in axial-vector ward identity

Description: It is shown how a new type of anomaly, in addition to the Adler--Bell--Jackiw anomaly, can occur in a gauge theory with ..gamma../sub 5/ couplings. Such an anomaly renders standard theories of quantum flavor dynamics nonrenormalizable. 19 references.
Date: January 1, 1978
Creator: Frampton, P.H.
Partner: UNT Libraries Government Documents Department

Strong CP violation and the neutron electric dipole moment revisited

Description: The relation between the CP violating operator {theta}F{tilde F} and its effective version L{sub CP}{sup eff} is reconsidered on the basis of the anomalous Ward-Takahashi (WT) identity. The consistency of the previous phenomenological calculations of the neutron electric dipole moment (NEDM) with the WT identity is critically examined. A consistent evaluation of an O(N{sub c}{sup o}) contribution to NEDM is given and the result is compared with the leading term in the chiral expansion which is O(N{sub c}{sup {minus}1}).
Date: July 1, 1991
Creator: Aoki, Sinya & Hatsuda, Tetsuo
Partner: UNT Libraries Government Documents Department

Mode analysis and Ward identities for perturbative quantum gravity in de Sitter space

Description: We study linearized gravitons on the D-dimensional open submanifold spanned by de Sitter conformal coordinates. The physical modes are found in the same way as for flat space by imposing exact gauge conditions on the invariant field equations and then exploiting the residual gauge freedom of solutions. The resulting polarization tensors have vanishing zero components and are transverse and traceless, just as in flat space. We also show that vacua exist such that the ghost and graviton propagators obey the Ward identity relating them.
Date: June 1, 1992
Creator: Tsamis, N. C. & Woodard, R. P.
Partner: UNT Libraries Government Documents Department

Dryson equations, Ward identities, and the infrared behavior of Yang-Mills theories. [Schwinger-Dyson equations, Slavnov-Taylor identities]

Description: It was shown using the Schwinger-Dyson equations and the Slavnov-Taylor identities of Yang-Mills theory that no inconsistency arises if the gluon propagator behaves like (1/p/sup 2/)/sup 2/ for small p/sup 2/. To see whether the theory actually contains such singular long range behavior, a nonperturbative closed set of equations was formulated by neglecting the transverse parts of GAMMA and GAMMA/sub 4/ in the Schwinger-Dyson equations. This simplification preserves all the symmetries of the theory and allows the possibility for a singular low-momentum behavior of the gluon propagator. The justification for neglecting GAMMA/sup (T)/ and GAMMA/sub 4//sup (T)/ is not evident but it is expected that the present study of the resulting equations will elucidate this simplification, which leads to a closed set of equations.
Date: January 1, 1979
Creator: Baker, M.
Partner: UNT Libraries Government Documents Department

Strong CP violation and the neutron electric dipole moment revisited

Description: The relation between the CP violating operator {theta}F{tilde F} and its effective version L{sub CP}{sup eff} is reconsidered on the basis of the anomalous Ward-Takahashi (WT) identity. The consistency of the previous phenomenological calculations of the neutron electric dipole moment (NEDM) with the WT identity is critically examined. A consistent evaluation of an O(N{sub c}{sup o}) contribution to NEDM is given and the result is compared with the leading term in the chiral expansion which is O(N{sub c}{sup {minus}1}).
Date: July 1, 1991
Creator: Aoki, Sinya (State Univ. of New York, Stony Brook, NY (United States). Inst. for Theoretical Physics) & Hatsuda, Tetsuo (Washington Univ., Seattle, WA (United States). Inst. for Nuclear Theory)
Partner: UNT Libraries Government Documents Department

Mode analysis and Ward identities for perturbative quantum gravity in de Sitter space

Description: We study linearized gravitons on the D-dimensional open submanifold spanned by de Sitter conformal coordinates. The physical modes are found in the same way as for flat space by imposing exact gauge conditions on the invariant field equations and then exploiting the residual gauge freedom of solutions. The resulting polarization tensors have vanishing zero components and are transverse and traceless, just as in flat space. We also show that vacua exist such that the ghost and graviton propagators obey the Ward identity relating them.
Date: June 1, 1992
Creator: Tsamis, N.C. (Crete Univ., Iraklion (Greece). Dept. of Physics) & Woodard, R.P. (Florida Univ., Gainesville, FL (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

Pseudoscalar decay constants and eta. -->. 3. pi. in chiral and 1/N perturbation theory

Description: The normal and anomalous chiral Ward identities are reexamined from the point of view of chiral and 1/ perturbation theory. Constraints of psi ..-->.. eta ..gamma.. and psi ..-->.. eta' ..gamma.. and pseudoscalar two photon decays are imposed, yielding a system of six simultaneous equations. A solution for the pseudoscalar decay constants is found which is relatively insensitive to the unknown gluonic bound states. The decay eta ..-->.. 3..pi.. is then calculated using these results, with good agreement with recent measurements.
Date: January 1, 1980
Creator: Milton, K.A.; Palmer, W.F. & Pinsky, S.S.
Partner: UNT Libraries Government Documents Department

Soliton masses in supersymmetric theories. [Semiclassical approximation, Ward identity]

Description: The semiclassical approximation - the familiar sum of frequencies - to the quantum-mechanical masses of solitons is ambiguous in theories with supersymmetric couplings: The approximation is unacceptably sensitive to the definition of the infinite-volume limit. The ambiguity can be resolved by means of a systematic mass-calculation procedure derived from the supersymmetry algebra. This method is applied to a large class of two-dimensional models, and finds that in 0(Dirac constant) the quantum-mechanical mass of a kink differs from its classical mass by a universal expression that has no dependence on the details of the interaction. The difference contains an ultraviolet divergence that exactly cancels the divergence in the classical mass. This contradicts recent claims that the difference must be zero. This result can also be checked using a number of other techniques, but it is argued that in space-times of dimension greater than two only the procedure derived from the supersymmetry algebra is likely to have any practical value. In two dimensions the difference between the quantum and classical masses can be related to properties of the amplitudes with which elementary bosons and fermions are scattered by a kink-antikink pair. Contrary to naive expectations these amplitudes are not identical; they nevertheless satisfy a supersymmetry Ward identity.
Date: January 1, 1979
Creator: Schonfeld, J.F.
Partner: UNT Libraries Government Documents Department