Search

Inclusive $J/\ensuremath{\psi}$ production in ${e}^{+}{e}^{\ensuremath{-}}$ annihilation is studied in the framework of NRQCD. We first review the leading-order calculations of the cross sections for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}c\overline{c}$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}\mathrm{gg}$ and find that their ratio is about 1:1.5 at $\sqrt{s}\ensuremath{\simeq}10\mathrm{GeV}.$ This result is in conflict with the current measurements by the Belle Collaboration, which finds that the process ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}J/\ensuremath{\psi}c\overline{c}$ accounts for about 2/3 of all the prompt $J/\ensuremath{\psi}'s.$ We find that the discrepancy problems in the total rate as well as in the $J/\ensuremath{\psi}$ momentum distributions can be resolved by postulating a large renormalization K factor $(K\ensuremath{\simeq}4)$ for the $J/\ensuremath{\psi}c\overline{c}$ cross section and by taking into account collinear suppression in the end-point energy region of $J/\ensuremath{\psi}\mathrm{gg}$ production. Detailed studies of the model predictions in terms of the density matrix are performed and various momentum and angular distributions are presented as functions of the K factors. These distributions can be used to determine the normalizations of each subprocess provided that the production and decay angular distributions do not alter much by higher-order corrections.

We calculate g–2 of the muon and the QED coupling alpha(MZ2), by improving the determination of the hadronic vacuum polarization contributions and their uncertainties. We include the recently reanalyzed CMD-2 data on e+e–-->pi+pi–. We carefully combine a wide variety of data for the e+e– production of hadrons and obtain the optimum form of R(s)[equivalent]sigmahad0(s)/sigmapt(s), together with its uncertainty. Our results for the hadronic contributions to g–2 of the muon are amuhad,LO = (692.4±5.9exp±2.4rad)×10–10 and amuhad,NLO = (–9.8±0.1exp±0.0rad)×10–10, and for the QED coupling Deltaalphahad(5)(MZ2) = (275.5±1.9exp±1.3rad)×10–4. These yield (g–2)/2 = 0.00116591763(74), which is about 2.4sigma below the present world average measurement, and alpha(MZ2)–1 = 128.954±0.031. We compare our g–2 value with other predictions and, in particular, make a detailed comparison with the latest determination of g–2 by Davier et al.

We study the one-loop effects of charginos and neutralinos on the helicity amplitudes for ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{W}^{+}{W}^{\ensuremath{-}}$ in the minimal supersymmetric standard model. The calculation is tested by using two methods. First, the sum rule for the form factors between ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{W}^{+}{W}^{\ensuremath{-}}$ and the process where the external ${W}^{\ifmmode\pm\else\textpm\fi{}}$ bosons are replaced by the corresponding Goldstone bosons ${\ensuremath{\omega}}^{\ifmmode\pm\else\textpm\fi{}}$ is employed to test the analytic expression and the accuracy of the numerical program. Second, the decoupling property in the large mass limit is used to test the overall normalization of the amplitudes. These two tests are most effectively carried out when the amplitudes are expanded in terms of the modified minimal subtraction $(\overline{\mathrm{MS}})$ couplings of the standard model. The resulting perturbation expansion is valid at collider energies below and around the threshold of the light supersymmetric particles. We find that the corrections to the cross section of the longitudinally polarized W-pair production can be as large as $\ensuremath{-}1.4%$ at the threshold of the light chargino-pair production for large scattering angles. We also study the effects of the CP-violating phase in the chargino and neutralino sectors on the helicity amplitudes. We find that the resulting CP-violating asymmetries can be at most 0.1%.

We study the potential of a very long baseline neutrino oscillation experiment with a neutrino factory and a large segmented water-Cerenkov calorimeter detector in resolving the degeneracies in the neutrino oscillation parameters; the sign of the larger mass-squared difference $\delta m^2_{13}$, the sign of $|U_{\mu 3}|^2 (\equiv \sin^2\theta_{ATM)-1/2$, and a possible two-fold ambiguity in the determination of the CP phase $\delta_{MNS}$. We find that the above problems can be resolved even if the particle charges are not measured. The following results are obtained in our exploratory study for a neutrino factory which delivers $10^{21}$ decaying $\mu^+$ and $\mu^-$ at 10 GeV and a 100 kton detector which is placed 2,100 km away and is capable of measuring the event energy and distinguishing $e^\pm$ from $\mu^\pm$, but not their charges. The sign of $\delta m^2_{13}$ can be determined for $4|U_{e3}|^2(1-|U_{e3}|^2)\equiv \sin^22\theta_{RCT}\gsim 0.008$. That of $\sin^2\theta_{ATM}-1/2$ can be resolved for $\sin^22\theta_{ATM}=0.96$ when $\sin^22\theta_{RCT}\gsim 0.06$. The CP-violating phase $\delta_{MNS}$ can be uniquely constrained for $\sin^22\theta_{RCT}\gsim 0.02$ if its true value is around $90^\circ$ or $270^\circ$, while it can be constrained for $\sin^22\theta_{RCT}\gsim 0.03$ if its true value is around $0^\circ$ or $180^\circ$., Comment: 15 pages,6 figures, More discussions added together with some figures. References added

We investigate the spin polarization of \tau^{\pm} leptons produced in \nu_{\tau} and \bar{\nu}_{\tau} nucleon scattering via charged currents. Quasi-elastic scattering, \Delta resonance production and deep inelastic scattering processes are studied. The polarization information is essential for measuring the \tau^{\pm} appearance rate in long baseline neutrino oscillation experiments, because the decay particle distributions depend crucially on the \tau^{\pm} spin. In this article, we calculate the spin density matrix of each process and estimate the spin polarization vector in medium and high neutrino energy interactions. We find that the produced \tau^{\pm}'s have high degree of polarization, and their spin direction depends non-trivially on the energy and the scattering angle of \tau^{\pm} in the laboratory frame., Comment: 23 pages, 35 figures; compile errors corrected; notation errors in Eq.(30) and (31) corrected, typo error in Eq.(40) corrected, references and comments in footnote added

The searches at LEP II for the processes ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{h}^{0}Z$ and ${e}^{+}{e}^{\ensuremath{-}}\ensuremath{\rightarrow}{h}^{0}{A}^{0}$ in the minimal supersymmetric standard model fail to exclude regions of the ${m}_{h}{,m}_{A}$ plane where $\mathrm{tan}\ensuremath{\beta}l1,$ thus allowing a very light ${A}^{0}$ ${(m}_{A}l20 \mathrm{GeV}).$ Such a parameter choice would predict a light ${H}^{\ifmmode\pm\else\textpm\fi{}}$ with ${m}_{{H}^{\ifmmode\pm\else\textpm\fi{}}}l{m}_{W}.$ Although the potentially large branching ratio for ${H}^{\ifmmode\pm\else\textpm\fi{}}\ensuremath{\rightarrow}{A}^{0}{W}^{*}$ would ensure that ${H}^{\ifmmode\pm\else\textpm\fi{}}$ also escaped detection in direct searches at LEP II and the Tevatron Run I, we show that this elusive parameter space is overwhelmingly disfavored by electroweak precision measurements through its large contribution to the $\mathrm{Zb}\overline{b}$ vertex.

We study the sensitivity of a long-base-line (LBL) experiment with neutrino beams from the High Intensity Proton Accelerator (HIPA), that delivers 10^{21} POT per year, and a proposed 1Mt water-Cherenkov detector, Hyper-Kamiokande (HK) 295km away from the HIPA, to the CP phase (delta_{M N S}) of the three-flavor lepton mixing matrix. We examine a combination of the nu_mu narrow-band beam (NBB) at two different energies, vev{p_pi}=2, 3GeV, and the bar{nu}_mu NBB at vev{p_pi}=2GeV. By allocating one year each for the two nu_mu beams and four years for the bar{nu}_mu beam, we can efficiently measure the nu_mu to nu_e and bar{nu}_mu to bar{nu}_e transition probabilities, as well as the nu_mu and bar{nu}_mu survival probabilities. CP violation in the lepton sector can be established at 4sigma (3sigma) level if the MSW large-mixing-angle scenario of the solar-neutrino deficit is realized, |\dmns| or |delta{M N S}-180^{circ}| > 30^{circ}, and if 4|U_{e3}|^2 (1-|U_{e3}|^2) equiv sin^2 2 theta_{CHOOZ} > 0.03 (0.01). The phase delta_{M N S} is more difficult to constrain by this experiment if there is little CP violation, delta_{M N S} sim 0^{circ} or 180^{circ}, which can be distinguished at 1sigma level if sin^2 2 theta_{CHOOZ} >~ 0.01., 16 pages, 4 figures, 2 tables, we add 1 figure, some refrences, and minor corrections. PLB published version

We calculate (g-2)/2 of the muon, by improving the determination of the hadronic vacuum polarisation contribution, a_mu^{had,LO}, and its uncertainties. The different e+e- data sets for each exclusive (and the inclusive) channel are combined in order to obtain the optimum estimate of the cross sections and their uncertainties. QCD sum rules are evaluated in order to resolve an apparent discrepancy between the inclusive data and the sum of the exclusive channels. We conclude a_mu^{had,LO}=(683.1 +- 5.9_{exp} +- 2.0_{rad}) 10^{-10} which, when combined with the other contributions to (g-2)/2, is about 3 sigma below the present world average measurement., Comment: 8 pages, LaTeX, 3 PostScript figures included. For completeness, we have added a recent prediction of the hadronic contribution by F. Jegerlehner

We study physics potential of Very Long Base-Line (VLBL) Neutrino-Oscillation Experiments with the High Intensity Proton Accelerator (HIPA), which will be completed by the year 2007 in Tokai-village, Japan, as a joint project of KEK and JAERI (Japan Atomic Energy Research Institute). The HIPA 50 GeV proton beam will deliver neutrino beams of a few GeV range with the intensity about two orders of magnitude higher than the present KEK beam for K2K experiment. As a sequel to the proposed HIPA-to-Super-Kamiokande experiment, we study impacts of experiments with a 100 kton-level detector and the base-line length of a few-thousand km. The pulsed narrow-band nu_mu beams (NBB) allow us to measure the nu_mu to nu_e transition probability and the nu_mu survival probability through counting experiments at large water-Cerenkov detector. We study sensitivity of such experiments to the neutrino mass hierarchy, the mass-squared differences, the three angles, and one CP phase of the three-generation lepton-flavor-mixing matrix. We find that experiments at a distance between 1,000 and 2,000 km can determine the sign of the larger mass-squared difference (m_3^2-m_1^2) if the mixing between nu_e and nu_3 (the heaviest-or-lightest neutrino) is not too small; 2|U_{e3}|^2(1-|U_{e3}|^2) gsim 0.03. The CP phase can be constrained if the |U_{e3}| element is sufficiently large, 2|U_{e3}|^2(1-|U_{e3}|^2) gsim 0.06, and if the smaller mass-squared difference (m_2^2-m_1^2) and the U_{e2} element are in the prefered range of the large-mixing-angle solution of the solar-neutrino deficit. The magunitude | m_3^2-m_1^2| and the matrix element U_{mu 3} can be precisely measured, but we find little sensitivity to m_2^2-m_1^2 and the matrix element U_{e2}., 65 pages, 22 figures, and 9 tables

We investigate the observability of the lightest Higgs boson in the gluon-fusion channel at the CERN Large Hadron Collider (LHC) in the minimal supersymmetric Standard Model with explicit CP-violating mixing among three neutral Higgs bosons. The lightest Higgs boson with its mass less than 130 GeV can be detected at the LHC via its gluon-fusion production followed by the decay into two photons. The explicit CP violation can suppress both the production cross section and the two-photon decay branching fraction so significantly that the signal cross section may be more than ten times smaller than the SM signal. This reduction factor can be as small as 1/40 if the lightest Higgs boson mass is 115 GeV and its production cross section at LEP2 is more than 90 % that of the SM case., 12 pages, 4 eps figures, a reference with two papers added

We review the most important topics and objectives of the physics program of the gamma-gamma, gamma-electron collider (photon collider) option for an e+e- linear collider., Comment: 36 pages, Latex, 11 figures(ps,eps), Talk at Intern. Workshop on High Energy Photon Colliders; June 14-17, 2000, DESY, Hamburg, Germany; to be published in Nucl. Instr. and Methods A

We propose a new mechanism for explaining the very long lifetime of superheavy dark matter X, which is proposed as a source of the ultra high-energy cosmic rays above the GZK cutoff (5 \times 10^{19} eV). The singlet X particle couples to the MSSM particles only through a bulk singlet field which develops the v.e.v. in the ``hidden'' brane. The distance between this hidden brane and the ``visible'' brane naturally leads to the exponential suppression of the coupling. The X particle decays predominantly into the higgsino and higgs boson of the MSSM, and its decay spectrum is completely determined once their properties are known., Comment: 7 pages, no figures. To appear in Phys.Lett.B

We re-evaluate the decays of the Higgs bosons in the minimal supersymmetric standard model (MSSM) where the tree-level CP invariance of the Higgs potential is explicitly broken by the loop effects of the third-generation squarks with CP-violating soft-breaking Yukawa interactions. This study is based on the mass matrix of the neutral Higgs bosons that is valid for arbitrary values of all the relevant MSSM parameters. It extends the previous work considerably by including neutral Higgs-boson decays into virtual gauge bosons and those into top-squark pairs, by implementing squark-loop contributions to the two-gluon decay channel, and by incorporating the decays of the charged Higgs boson. The constraints from the electron electric dipole moment on the CP phases are also discussed. We find that the branching fractions of both the neutral and charged Higgs-boson decays and their total decay widths depend strongly on the CP phases of the top (and bottom) squark sectors through the loop-induced neutral Higgs boson mixing as well as the direct couplings of the neutral Higgs bosons to top squark pairs., Comment: 17 pages, 5 eps figures. Comments on the color and electric-charge breaking minima and references added. To appear in the Phys. Rev. D

We present a model-independent study of the effects of a neutral Higgs boson without definite CP-parity in the process $\gamma\gamma \to t\bar{t}$ around the mass pole of the Higgs boson. Near the resonance pole, the interference between the Higgs-exchange and the continuum amplitudes can be sizable if the photon beams are polarized and helicities of the top and anti-top quarks are measured. Study of these interference effects enables one to determine the CP property of the Higgs boson completely. An example of the complete determination is demonstrated in the context of the minimal supersymmetric standard model., Comment: 17 pages, LaTeX file with 1 eps figure

We study one-loop effects of sfermions on helicity amplitudes for ${e}^{\ensuremath{-}}{e}^{+}\ensuremath{\rightarrow}{W}^{\ensuremath{-}}{W}^{+}$ in the minimal supersymmetric standard model. The one-loop contributions are calculated in the modified minimal subtraction scheme $(\overline{\mathrm{MS}})$ renormalization scheme. In order to verify the validity of the analytic calculation and the numerical program, the following tests are performed. (i) The Becchi-Rouet-Stora sum rules hold exactly among the analytic expressions of the form factors of the ${e}^{\ensuremath{-}}{e}^{+}\ensuremath{\rightarrow}{W}^{\ensuremath{-}}{W}^{+}$ amplitude and those of the amplitudes where the external ${W}^{\ifmmode\pm\else\textpm\fi{}}$ bosons are replaced by the corresponding Goldstone bosons ${\ensuremath{\chi}}^{\ifmmode\pm\else\textpm\fi{}};$ hence, they hold within the expected accuracy of the numerical program. (ii) The one-loop sfermion contribution to the amplitudes decouple in the heavy mass limit. This property is used to test the overall normalization of the amplitudes. In order to observe the analytically exact decoupling, the amplitudes are expanded by the $\overline{\mathrm{MS}}$ couplings of the standard model. (iii) The high-energy analytic formulas of the helicity amplitudes, which are verified by using the equivalence theorem analytically, are used for the numerical test of the high-energy behavior of the amplitudes. We then investigate the magnitude of the one-loop effects on each helicity amplitude which may be measured by experiments at future linear colliders. Under the constraint from available precision data, the one-loop corrections to a few helicity amplitudes (for example, the longitudinal-W-pair production) can be at most from -0.8% to +0.6% in magnitude in the observables. The corrections in the helicity-summed cross sections are smaller, typically a few times \ifmmode\pm\else\textpm\fi{}0.1% at large scattering angles.

We study constraints on the supersymmetric standard model from the updated electroweak precision measurements --- the Z-pole experiments and the $W$-boson mass measurements. The supersymmetric-particle contributions to the universal gauge-boson-propagator corrections are parametrized by the three oblique parameters Sz, Tz and mw. The oblique corrections, the Zqq and Zll vertex corrections, and the vertex and box corrections to the \mu-decay width are separately studied in detail. We first study individual contribution from the four sectors of the model, the squarks, the sleptons, the supersymmetric fermions (charginos and neutralinos), and the supersymmetric Higgs bosons, to the universal oblique parameters, where the sum of individual contributions gives the total correction. We find that the light squarks or sleptons, whose masses just above the present direct search limits, always make the fit worse than that of the Standard Model (SM), whereas the light charginos and neutralinos generally make the fit slightly better. The contribution from the supersymmetric Higgs sector is found small. We then study the vertex/box corrections carefully when both the supersymmetric fermions (-inos) and the supersymmetric scalars (squarks and sleptons) are light, and find that no significant improvement over the SM fit is achieved. The best overall fit to the precision measurements are found when charginos of mass $\sim 100\gev$ with a dominant wino-component are present and the doublet squarks and sleptons are all much heavier. The improvement over the SM is marginal, however, where the total \chi^2 of the fit to the 22 data points decreases by about one unit, due mainly to a slightly better fit to the $Z$-boson total width., Comment: 61 pages, 16 figures. References added. version to appear in Nuclear Physics B

Weak boson fusion is a copious source of intermediate mass Higgs bosons at the LHC. The additional very energetic forward jets in these events provide for powerful background suppression tools. We analyze the $\stackrel{\ensuremath{\rightarrow}}{H}\ensuremath{\tau}\ensuremath{\tau}$ decay mode for the standard model Higgs boson. A parton level analysis of the dominant physics backgrounds (mainly $\stackrel{\ensuremath{\rightarrow}}{Z}\ensuremath{\tau}\ensuremath{\tau}$ and Drell-Yan production of \ensuremath{\tau}'s) and of reducible backgrounds (from $W+\mathrm{jet}$ and $b\overline{b}$ production in association with two jets and subsequent leptonic decays) demonstrates that this channel allows the observation of $\stackrel{\ensuremath{\rightarrow}}{H}\ensuremath{\tau}\ensuremath{\tau}$ in a low background environment, yielding a significant Higgs signal with an integrated luminosity of about $30{\mathrm{fb}}^{\mathrm{\ensuremath{-}}1}.$ The weak boson fusion process thus allows direct measurement of the $H\ensuremath{\tau}\ensuremath{\tau}$ coupling.

We explain the imbalance of the flavor mixing angles between the quark and the lepton sectors in the context of the SU(5) GUT with the see-saw mechanism. The quark masses and the CKM matrix elements are obtained by using, respectively, the Fritzsch and Branco - Silva-Marcos form for the up- and down-quark Yukawa matrices (y^u and y^d) at the GUT scale. The charged-lepton Yukawa matrix (y^e) is the transpose of y^d, modified by the Georgi-Jarlskog factor. We show that the neutrino masses and mixing angles suggested by the recent solar and atmospheric neutrinos are then obtained from a simple texture of the neutrino Yukawa matrix (y^\nu) and a diagonal right-handed Majorana mass matrix at the GUT scale., Comment: 30 pages, no figure

We study the constraints from updated electroweak data on the three leptophobic $Z'$ models, the ${\eta}$ model with an appropriate $U(1)'-U(1)_Y$ kinetic mixing, a $Z'$ model motivated by the flipped SU(5) \times U(1) unification, and the phenomenological $Z'$ model of Agashe, Graesser, and Hinchliffe. The $Z-Z'$ mixing effects are parametrized in terms of a positive contribution to the $T$ parameter, $T_{new}$, and the effective mass mixing parameter, $\bar{\xi}$. All the theoretical predictions for the $Z$ boson parameters, the $W$ boson mass and the observables in low-energy neutral current experiments are presented together with the standard model radiative corrections. The allowed region in the ($\bar{\xi},T_{new}$) plane is shown for the three models. The 95% CL lower limit on the heavier mass eigenstate $Z_2$ is given as a function of the effective $Z-Z'$ mixing parameter $\zeta$.

We study constraints on additional $Z'$ bosons predicted in the supersymmetric (SUSY) $E_6$ models by using the updated results of electroweak experiments -- $Z$-pole experiments, $m_W$ measurements and low-energy neutral current (LENC) experiments. We find that the effects of $Z$-$Z'$ mixing are parametrized by (i) a tree-level contribution to the $T$-parameter, (ii) the effective $Z$-$Z'$ mass mixing angle $\xibar$. In addition, the effect of the direct exchange of the heavier mass eigenstate $Z_2$ in the LENC processes is parametrized by (iii) a contact term $\contact$. We give the theoretical predictions for the observables in the electroweak experiments together with the standard model radiative corrections. Constraints on $T_{\rm new}$ and $\xibar$ from the $Z$-pole and $m_W$ experiments and those on $\contact$ from the LENC experiments are separately shown. Impacts of the kinetic mixing between the ${\rm U(1)}_Y$ and ${\rm U(1)'}$ gauge bosons on the $\chi^2$-analysis are studied. We show the 95% CL lower mass limit of $Z_2$ as a function of the effective $Z$-$Z'$ mixing parameter $\zeta$, a combination of the mass and kinetic mixings. Theoretical prediction on $\zeta$ and $g_E$ is found for the $\chi, \psi, \eta$ and $\nu$ models by assuming the minimal particle content of the SUSY $E_6$ models. In a certain region of the parameter space, the $Z_2$ boson mass in the detectable range of LHC is still allowed., Comment: LaTeX, 36pages, 4 figures. One referece added. Final version to appear in Nucl. Phys. B

We consider $e e q q$ contact interactions as a possible origin of an excess of events above Standard Model predictions in $e^+ p \to e^+ jet$ at high $Q^2$ observed by the H1 and ZEUS collaborations at HERA. The HERA data prefer chirality RL or LR contact terms and atomic physics parity violation measurements severely limit parity-odd contact terms. With equal left-right and right-left chirality interactions at an effective scale of order 3 TeV we are able to reproduce the main features of the HERA data and still be consistent with Drell-Yan pair production at the Tevatron and hadron production at LEP 2 and TRISTAN., Comment: RevTex, 12 pages, 4 figures. Slight changes in Figs.2 and 3

The string theory predicts the unification of the gauge couplings and gravity. The minimal supersymmetric Standard Model, however, gives the unification scale $\sim 2\times 10^{16}$ GeV which is significantly smaller than the string scale $\sim 5\times 10^{17}$ GeV of the weak coupling heterotic string theory. We study the unification scale of the non-supersymmetric minimal Standard Model quantitatively at the two-loop level. We find that the unification scale should be at most $\sim 4\times 10^{16}$ GeV and the desired Kac-Moody level of the hyper-charge coupling should be $1.33 \lsim \ky \lsim 1.35$ in the absence of significant string threshold effects., Comment: LaTeX, 13pages, 3 figures. Some comments are added. Final version to appear in Phys. Lett. B

We perform a global fit of data relevant to $eeqq$ contact interactions, including deep inelastic scattering at high $Q^2$ from ZEUS and H1, atomic physics parity violation in Cesium from JILA, polarized $e^-$ on nuclei scattering experiments at SLAC, Mainz and Bates, Drell-Yan production at the Tevatron, the total hadronic cross section $\sigma_{had}$ at LEP, and neutrino-nucleon scattering from CCFR. With only the new HERA data, the presence of contact interactions improves the fit compared to the Standard Model. When other data sets are included, the size of the contact contributions is reduced and the overall fit represents no real improvement over the Standard Model., Comment: 26 pages (now single-spaced), Revtex, 2 eps figures, uses epsf.sty. Some clarifications, minor corrections, 2 new references, also 3 new tables which present 95% CL bounds on the contact interaction scales Lambda

This report summarizes the highlights of the 1996 {ital Review} {ital of} {ital Particle} {ital Physics} (Phys. Rev. D {bold 54}, 1 (1996)). Using data from previous editions, plus 1900 new measurements from 700 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. We also give numerous reviews, tables, figures, and formulae. The present edition marks the apparent completion of the table of Standard Model quarks with the discovery of the top. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of the full {ital Review}. {copyright} {ital 1996 The American Physical Society.}

The most important hint of physics beyond the Standard Model (SM) from the 1995 precision electroweak data is that the most precisely measured quantities, the total, leptonic and hadronic decay widths of the $Z$ and the effective weak mixing angle, $\sin^2\theta_W$, measured at LEP and SLC, and the quark-lepton universality of the weak charged currents measured at low energies, all agree with the predictions of the SM at a few $\times 10^{-3}$ level. By taking into account the above constraints I examine implications of three possible disagreements between experiments and the SM predictions. It is difficult to interpret the 11\% (2.5-$\sigma$) deficit of the $Z$-partial-width ratio $R_c=\Gamma_c/\Gamma_h$, since it either implies an unacceptably large $\alpha_s$ or a subtle cancellation among hadronic $Z$ decay widths in order to keep all the other successful predictions of the SM. The 2\% (3-$\sigma$) excess of the ratio $R_b=\Gamma_b/\Gamma_h$ may indicate the presence of a new rather strong interaction, such as the top-quark Yukawa coupling in the supersymmetric (SUSY) SM or a new interaction responsible for the large top-quark mass in the Technicolor scenario of dynamical electroweak symmetry breaking. Another interpretation may be additional tree-level gauge interactions that couple only to the third generation of fermions. A common consequence of these attempts is a rather small $\alpha_s$, $\alpha_s(\mz )_{\msbar}=0.104\pm 0.08$. The 0.17\% (1-$\sigma$) deficit ..., Comment: Talk presented at Yukawa International Seminar (YKIS)~'95, 23 pages, uuencoded compressed tar file of LaTeX file and 13 EPS files (uses ptptex.sty,wrapfig.sty,psfig.sty,axodraw.sty) PostScript version of complete paper available at ftp://ftp.kek.jp/kek/preprints/TH/TH-463/kekth463.ps.gz

Our numerical results are not affected by these errors. In Section 3 we stated that “the form factor Fp(q) has not been measured experimentally”. We learned that there are some experiments which measure the pseudoscalar form factors in muon capture [1] and in pion electroproduction [2]. Those experiments found results consistent with the PCAC relation at very low Q2, but they are not sensitive to the

We show that the flavor-diagonal gauge boson of the extended technicolor theory contributes with opposite sign to the standard model correction for the $Zbb$ vertex. This mechanism can naturally explain the deviation of the LEP result from the standard model prediction for the partial width $\Gamma(Z \rightarrow b{\bar b})$. A smaller value of the QCD coupling, $\alpha_s(m_Z) \simeq 0.115$, is then preferred by the $\Gamma(Z \rightarrow \mbox{hadron})$ data, which is consistent with both the recent Lattice-QCD estimate and the Particle Data Group average., Comment: 12 pages, latex (using subeqnarray.sty), no figures

We probe the top-quark electric dipole moment (EDM) in top-quark pair production via photon-photon fusion at a photon linear collider. We show how linearly-polarized photon beams can be used to extract information on the top-quark EDM without the use of complicated angular correlations of top-quark decay products. If the luminosity of the laser back-scattered photon-photon collisions is comparable to that of the $e^+e^-$ collisions, then the measurement of the top-quark EDM obtained by counting top-quark-production events in photon fusion can be as accurate as the measurement obtained by studying the $t\bar{t}$ decay correlations in $e^+e^-$ collisions using a perfect detector., Comment: Latex, 11 pages, 1 figure (not included). One compressed postscript file of the paper available at ftp://ftp.kek.jp/kek/preprints/TH/TH-443/kekth443.ps.gz

Extensions of the Standard Model which involve a new scale, $\Lambda$, may, for energies sufficiently small compared to this new scale, be expressed in terms of operators with energy dimension greater than four. The coefficients of just four SU(2)$\times$U(1)-gauge-invariant energy-dimension-six operators are sufficient to parameterize the contributions of new physics in the electroweak bosonic sector to electroweak precision measurements. In this letter we update constraints on the coefficients of these four operators due to recent precision measurements of electroweak observables. We further demonstrate how such constraints may be improved by experiments at TRISTAN, LEP2 and at a future linear $e^+e^-$ collider. The relationship of these operators to the oblique parameters $S$, $T$ and $U$ is examined. Two of the operators contribute to a non-standard running of the electroweak charge form-factors $\overline{\alpha}(q^2)$, $\overline{s}^2(q^2)$, $\overline{g}_Z^2(q^2)$ and $\overline{g}_W^2(q^2)$; in the special case where the coefficients of these two vanish the operator analysis reduces to an analysis in terms of $S$, $T$ and $U$ with $U = 0$., Comment: documentstyle[preprint,aps,floats,cite,psfig,subeqn]{revtex}, one figure compressed and encoded using uufiles, .ps version available via anonymous ftp from ftp://ftp.kek.jp/kek/preprints/TH/TH-440

We update our Standard Model predictions for g-2 of the muon and for the hadronic contributions to the running of the QED coupling, Delta alpha_had^(5)(M_Z^2). Particular emphasis is put on recent changes in the hadronic contributions from new data in the 2pi channel and from the energy region just below 2 GeV. In particular, for the e+e- -> pi+pi- contribution we include the recent `radiative return' data from KLOE and BaBar. We also include the recent BaBar data on other exclusive channels. We make a detailed study of the effect of replacing the measurements of the inclusive cross section, sigma(e+e- -> hadrons), by the sum of the exclusive channels in the energy interval 1.43 < sqrt{s} < 2 GeV, which includes a QCD sum-rule analysis of this energy region. Our favoured prediction for the muon anomalous magnetic moment is (g-2)/2 = (11659182.8 +- 4.9)*10^(-10) which is 3.3 sigma below the present world-average measurement. We compare our g-2 value with other recent calculations. Our prediction for the QED coupling, obtained via Delta alpha_had^(5)(M_Z^2) = (276.26 +- 1.38)*10^(-4), is alpha(M_Z^2)^(-1) = 128.944 +- 0.019.

A non-standard symmetry breaking sector may lead to derivative couplings of the Higgs boson and thereby to anomalous interactions with the electroweak gauge bosons. In the framework of gauge-invariant effective Lagrangians the resulting changes in Higgs boson production and decay mechanisms are related to anomalous triple vector boson couplings. Using low energy constraints on the dimension-six operators in the effective Lagrangian, we discuss the size of deviations from SM predictions which may be expected in Higgs boson production and decay rates. Large enhancements are allowed {\it e.g.} in the $Z \to H \gamma$ and $H\to \gamma \gamma$ partial decay widths, leading to $Z\to \gamma\gamma\gamma$ events at LEP., Comment: 14 pages. Uses RevTEX. Four figures available upon request from szalapski@pheno.physics.wisc.edu or szalapski@wiscphen.bitnet

A measurement of the {tau} polarization at hadron colliders offers an excellent signal for the detection of charged Higgs bosons, via the decay {ital H}{sup {plus minus}}{r arrow}{tau}{sup {plus minus}}{nu}. We show how such a determination can distinguish these events from the {ital W}{sup {plus minus}}{r arrow}{tau}{sup {plus minus}}{nu} background, for each of the {tau}{r arrow}{pi}{nu}, {rho}{nu}, {ital a}{sub 1}{nu}, and {ital l}{nu}{bar {nu}} decay channels.

If the atmospheric neutrino oscillation amplitude, sin^2 2theta_atm is not maximal, there is a two fold ambiguity in the neutrino parameter space: sin^2 theta_atm>0.5 or sin^2 theta_atm0.12 (0.08) for the optimal combination of a 3.0^circ off-axis beam (OAB) at SK (L=295km) and a 0.5^circ OAB at L=1000km with a far detector of 100kton volume, after 5 years of exposure with 1.0(5.0) time 10^21 POT/year, if the hierarchy is normal. We also study the influence of the octant degeneracy on the capability of T2KK experiment to determine the mass hierarchy and the leptonic CP phase. The capability of rejecting the wrong mass hierarchy grows with increasing sin^2 theta_atm when the hierarchy is normal, whereas it is rather insensitive to sin^2 theta_atm for the inverted hierarchy. We also find that the 1sigma allowed region of the CP phase is not affected significantly even when the octant degeneracy is not resolved. All our results are obtained for the 22.5 kton Super-Kamiokande as a near detector and without an anti-neutrino beam., 23 pages, 9 figures

We propose a method to extract the charm structure function of the nucleon {ital c}({ital x},{ital Q}{sup 2}=m{sub W}{sup 2}) from measurements of the rapidity distribution of {ital W}{sup {plus minus}} and {ital Z} in {ital p{bar p}} collisions. The production of weak intermediate bosons via charm occurs at the few percent level at the Fermilab Tevatron and has in particular a strong influence on the important measurement of the ratio of {ital W} and {ital Z} events as {ital c{bar s}}{r arrow}{ital W} is expected to be much larger than {ital c{bar c}}{r arrow}{ital Z}.

We present an effective action for multiple production of longitudinally polarized {ital W}'s and {ital Z}'s via gluon fusion through a loop of a superheavy degenerate doublet of quarks. We utilize the equivalence'' of {ital W}{sub {ital L}}/Z{sub L} with Goldstone bosons. Total cross sections are estimated for up to ten weak bosons at Superconducting Super Collider energies, and their validity is discussed. Our result reproduces the exact calculation of the process {ital gg}{r arrow}{ital ZZ} in the relevant limit.

An excess of events with an isolated muon and low thrust observed by the MARK-J collaboration at the highest PETRA energy ~/~ = 46 7 GeV, is found to be consistent with the near threshold producuon of heavy quarks of charge - 1/3 A natural candidate is a fourth-generation "down" quark or, possibly, a member of a 27 representatmn of E 6 Signatures of such heavy quark pmr production at the CERN p~ colhder are investigated and it is concluded that the present data have a chance to confirm the signal

The next-to-leading-order quantum-chromodynamic correction to the hadronic annihilation rate of ground state para-quarkonia is calculated by dimensionally regularizing both ultraviolet and infrared singularities. The contribution from each infrared finite set of diagrams is found to agree with the one obtained by using massive gluon regularization. The renormalization prescription dependence of the magnitude of the next-to-leading-order correction is also discussed. The correction for the pseudoscalar bottomonium decay rate is found to be sufficiently small in the momentum subtraction scheme.

Parity-nonconserving asymmetries appear in the angular distribution of the charged leptons from the decay of $W$ bosons produced with high transverse momentum in hadron colliders. Absorptive parts of the amplitudes which produce the nonvanishing asymmetry are calculated in the one-loop order. The asymmetries grow rapidly with the $W$ transverse momentum ${q}_{T}$ and reach a 5% level at ${q}_{T}\ensuremath{\sim}20$ GeV. Measurements of the sign of the asymmetries will distinguish clearly between $V\ensuremath{-}A$ and $V+A$ couplings without polarization experiments.

Predictions of the scalar-quark-pair-production scenario, proposed to explain monojets observed at the CERN pp-bar collider, are extended to multijets with missing p/sub T/. The n-jet cross sections are calculated from lowest-order subprocesses as functions of scalar-quark and gluino masses. Predictions are made for azimuthal correlations ..delta..phi, pseudorapidity correlation ..delta..eta, and a jet transverse-momentum asymmetry in dijet events.

A summary is given of the results obtained by the Superstring working group. New physics phenomena arising from superstring models that might be detected at the SSC as well as their possible backgrounds were investigated. Topics examined were models with extra Z bosons and right handed W bosons, detection of Winos, Zinos and gluinos and production of heavy squarkonium.

The search at the Tevatron for events with large missing transverse momentum (pstroke;T), which set mass bounds exceeding 73 GeV for both squarks and gluinos, implies significantly improved mass limits on other exotic particles. We study various sources for pstroke;T events: production of leptoquarks or their fermionic partners in E6 models, Majorana leptogluons in composite models of quarks and leptons, and cosmions in a model which explains the solar neutrino and dark matter problems. The CDF data can already exclude neutral leptogluons with masses below 110 GeV, while an integrated luminosity of order 2 pb−1 would set lower mass bounds of order 100 GeV for the other exotic particles.

In pp-bar collider experiments, the higher-order QCD subprocesses qq-bar..-->..gQQ-bar, qg..-->..qQQ-bar, gg..-->..gQQ-bar (with Q = c,b) can lead to events with high-p/sub T/ leptons and apparently broad jets that may fake the usual signals of t-quark production and decay. We evaluate these contributions quantitatively, with plausible approximations, and conclude that the background they provide can be largely eliminated by suitable experimental selection criteria.

A spin-averaged interquark potential exhibiting the full content of perturbative QCD at short distances is discussed. Using the measured charmonium and bottomonium bound state levels and their leptonic widths, we find Λ M S = 250 ± 100 MeV in the effective four-quark theory. Observation of toponium states would not significantly improve the precision of this QCD scale parameter determination. The reason basically is that an increase in Λ MS correlated with an upward shift of all the heavy quark masses can result in very little change in the observables.

The sensitivity of the charmonium and bottomonium spectroscopy to the short distance part of the interquark potential is critically re-examined using the latest data. We confirm that the data cannot accomodate a QCD scale parameter\(\left( {\Lambda _{\overline {MS} } } \right)\) smaller than about 150 MeV, whereas we find no constraint on larger values for the scale parameter, contrary to a previous analysis. The effect of dynamical heavy quark masses in the loop correction to the perturbative potential is studied in detail and the effective four quark theory with a massive charmed quark is found to give an accurate description of the perturbative potential for quarkonia of mass up to about 200 GeV. It is argued that the experimental determination of the mass ande+e− decay width of the 1S and 2S toponium resonances (of mass round 80 GeV) with the accuracy anticipated at the forthcominge+e− colliders should enable the QCD scale parameter to be determined to within ±100 MeV.