[en] We present a critical analysis of the spontaneous symmetry breaking and the Higgs sector of the conventional SU(2)_L circle-times SU(2)_R circle-times U(1)_B-L left-right symmetric theory involving bi-doublet and triplet Higgs fields. We examine the phenomenological constraints imposed on the minimization of the Higgs potential arising from experimental observations, and explore the resulting consequences including the problem of ''fine- tuning'' arising from the hierarchy of mass scales involved. We show that it is non-trivial to satisfy all of these constraints. We contrast the benefits of this general class left-right models against the required ''fine-tuning'' necessary to force the phenomenology to conform to experimental fact. 17 refs., 1 fig

[en] The author obtains a model-independent lower bound on M/sub R/ of 300 GeV for a general class of SU(2)/sub L/ circle cross SU(2)/sub R/ circle cross U(1)/sub B-L/ left-right theories without any assumptions about the structure of the Cabibbo-Kobayashi-Maskawa matrices or the right-handed neutrino mass. The result is also independent of Higgs-boson, dispersive, and W/sub L/-W/sub R/ mixing contributions, and it holds for a range of bag constants, B. He also considers the minimal left-right symmetric electroweak model and characterizes the range of allowable masses for the physical Higgs boson. He uses two approaches: (1) the lowest order boson-boson scattering amplitude is computed and a unitarity constraint on the J = 0 partial-wave amplitude is imposed; (2) the radiative corrections to the Higgs propagator is computed and the range of Higgs masses for which the perturbation series converges is determined. Both methods give upper bounds on the Higgs masses in terms of the gauge boson masses, and the theoretical connection is discussed. The generalizations of these constraints and their applicability in light of previous bounds is examined

[en] We examine Drell-Yan μ-pair production and heavy quark pair production, and demonstrate how to implement precise comparisons between the theoretical predictions of QCD and the experimental observables. Specifically, we have dealt with theoretical uncertainties arising from higher order corrections, unknown small-χ behavior, and the unknown gluon distribution. We indicate how the above processes can provide discriminating tests of the theory in the kinematic regimes which will soon be investigated by the Tevatron I and HERA facilities. 8 refs., 6 figs

[en] We compare the results of the fixed-flavor scheme calculation of Laenen, Riemersma, Smith, and van Neerven with the variable-flavor scheme calculation of Aivazis, Collins, Olness, and Tung for the case of neutral-current (photon-mediated) heavy-flavor (charm and bottom) production. Specifically, we examine the features of both calculations throughout phase space and compare the structure function F₂(x,Q²). We also analyze the dependence of F₂ on the mass factorization scale μ. We find that the former is most applicable near threshold, while the latter works well for asymptotic Q². The validity of each calculation in the intermediate region is dependent upon the x and Q² values chosen

[en] The authors examine Drell-Yan μ-pair production and heavy quark pair production, and demonstrate how to implement precise comparisons between the theoretical predictions of QCD and the experimental observables. Specifically, they deal with theoretical uncertainties arising from higher order corrections, unknown small-x behavior, and the unknown gluon distribution. They indicate how the above processes can provide discriminating tests of the theory in the kinematic regimes which will soon be investigated by the Tevatron I and HERA facilities

[en] The effective-vector-boson method for high-energy collisions is precisely formulated by using factorization of the helicity amplitudes. All approximations related to kinematics are eliminated. Compact formulas for exact vector-boson distribution functions are derived. The on-mass-shell continuation of the vector-boson hard-scattering cross section is isolated and clarified. Improvements over the leading-logarithmic approximation are dramatic. Application of the new formalism to heavy-fermion and Higgs-boson production processes illustrates its extended range of accuracy and usefulness

[en] We examine the recent claim of a possible enhancement of the process enhancement of the process Z→π⁰γ through the axial anomaly. A critical analysis of the question reveals the deficiency in the proof, and no enhancement is seen in a model calculation. (orig.)

[en] We obtain a model-independent lower bound on M/sub R/ of 300 GeV for a general class of SU(2)/sub L/ x SU(2)/sub R/ x U(1)/sub Y/ left-right theories without any assumptions about the structure of the Cabibbo-Kobayashi-Maskawa matrices or the right-handed neutrino mass. Our result is also independent of Higgs-boson, dispersive, and W/sub L/-W/sub R/ mixing contributions, and it holds for a range of bag constants

[en] In a consistently formulated pQCD framework incorporating nonzero mass heavy quark partons, there is still the freedom to define parton distributions obeying either mass-independent or mass-dependent evolution equations, contrary to statements made in a recent paper by MRRS. With properly matched hard cross-sections, different choices merely correspond to different factorization schemes, and they yield the same physical cross-sections. We demonstrate this principle in a concrete order α_s calculation of the DIS charm structure function. We also examine the proper matching between parton definitions and subtractions in the hard cross-section near threshold where the calculation is particularly sensitive to mass effects of the heavy quark. The results obtained from the general-mass formalism are quite stable against different choices of scale and exhibit a smooth transition in the threshold region (using either mass-independent or mass-dependent evolution), in contrast to results of ref. [3]. copyright 1997 American Institute of Physics

[en] We consider the minimal left-right-symmetric electroweak model and characterize the range of allowable masses for the physical Higgs boson. We use two approaches: (1) We compute the lowest-order boson-boson scattering amplitude and impose a unitarity constraint on the J = 0 partial-wave amplitude; (2) we compute the radiative corrections to the Higgs-boson propagator and determine the range of Higgs-boson masses for which the perturbation series converges. Both methods give upper bounds on the Higgs-boson masses in terms of the gauge-boson masses, and we discuss the theoretical connection. The generalizations of these constraints and their applicability in light of previous bounds is examined