Two-jet production inp\bar p collisions

The production of two quark/gluon jets in \(p\bar p\) collisions is analyzed. We determine the cross section dependence on the transverse momentum, the rapidities, and on the two-jet invariant mass, and we evaluate the sensitivity of the results on the theoretical input assumptions and the experimental cuts. We extrapolate these results into the TeV energy region.     

Wino and zino production inp\bar p collisions: first order supersymmetric QCD corrections

We compute the first order supersymmetric QCD correction to wino \((\tilde W)\) and zino \((\tilde Z)\) production in \(p\bar p\) collisions via subprocesses involving two massless partons inside the nucleon or one massless parton and a massive SUSY parton (squark or gluino). The first order SQCD corrections to the rapidity dependence at CERN collider and Tevatron energies are found large (K～2). The rates are important (～10^?2 nb at \(\sqrt s = 630\) GeV and ～10^?1 nb at \(\sqrt s = 2\) TeV), as soon as the \((\tilde W)\) and \((\tilde Z)\) production by squarks is allowed. Transverse momentum distributions are also given and their shape is found very sensitive to the presence of SUSY partons inside the nucleon.     

Inclusive particle production inp\bar p collisions

We calculate the inclusive production of charged hadrons in collisions at the next-to-leading order in the QCD improved parton model using a new set of fragmentation functions for charged pions and kaons. We predict transverse-momentum distributions and compare them with experimental data from the CERN Collider and the Fermilab Tevatron.     

\mu\rightarrow e\gamma decay in the left-right supersymmetric model

We calculate the dipole amplitude for the decay and related processes in the left-right supersymmetric model when parity breaking occurs at a considerably large scale. The low-energy flavor violation in the model originates either from the nonvanishing remnants of the left-right symmetry in the slepton mass matrix or from the direct flavor changing lepton-slepton-neutralino interaction. The result is found to be large and already accessible with current experimental accuracy for supersymmetric masses not far above the electroweak scale. It also provides nontrivial constraints on the lepton mixing in the model. Received: 8 June 1998 / Published online: 15 October 1998     

\mu-e conversion in nuclei in the left-right supersymmetric model

We investigate the contributions to conversion in nuclei in a supersymmetric model with left-right symmetry, motivated by the new data on neutrino oscillations. We study the dependence of the conversion rate on the various parameters of the model, and show that light-mass or large scenarios are severely restricted. We analyse the effect of several popular mecahnisms of neutrino mixing on the conversion rate as well as the influence of the right-handed scale on the conversion rate. We compare the conversion rate to the branching ratio for and discuss their relative accessibility at future experiments, their sensitivity to various parameters of the model, as well as their relative importance in providing signals for new Physics. Received: 31 May 2000 / Published online: 31 August 2000     

Higher-order QCD corrections to inclusive particle production inp\bar p collisions

Inclusive single-particle production cross sections have been calculated including higher-order QCD corrections. Transverse-momentum and rapidity distributions are presented and the scale dependence is studied. The results are compared with experimental data from the CERN Collider and the Fermilab Tevatron.Supported by the Bundesministerium für Forschung und Technologie, 05 5HH 91P(8), Bonn, Germany     

Searching for new heavy vector bosons inp \bar p colliders

Production and detection of new heavy vector bosons is studied at present (or near future)p \(\bar p\) collider experiments. Application to CERN and Tevatron experiments is considered in detail, but some results for the UNKp \(\bar p\) collider, at \(\sqrt s \) = 6TeV, are also presented. Rather than considering a number of detailed models, we prefer to discuss some general, although necessarily schematic, classes of new vector bosons ranging from strongly interacting Higgs sector models to extended gauge models. We study in particular signals and backgrounds in the \(\ell \overline \ell jj\) channels, where ? are leptons andj are hadron jets.     

Ranges of interaction inp\bar p scattering at low energies

Thep¯ p cross sections at low energies are analysed in the framework of the optical model. It is shown that the annihilation range is closely related to the size of the proton as measured in electromagnetic and hadronic interactions. At larger distances thep¯ p interaction has the similar character as the NN one.     

Production of colourless scalar resonance inp\bar p annihilation

We analyse under what conditions the production of colourless scalar resonance (Higgs boson) can be enhanced and its subsequent decays into gauge bosons and/or light Higgs bosons can provide a test for them. We discuss the expected experimental signatures and point out difficulties of obtaining large coupling to light quarks in the framework of a multi Higgs doublet model with horizontal symmetry.     

Leptonic dipole moments in the left-right supersymmetric model

The observation of neutrino oscillations imposes a pattern of mixing in both the sneutrino and charged slepton sectors. On the other hand, the apparent 2.6 deviation of the anomalous magnetic moment of the muon from the standard model value favors a scenario beyond the standard model. We show that, in a supersymmetric model with left-right symmetry, which provides an explanation for both phenomena, the relationship between flavor conserving dipole moments, such as the magnetic and the electric dipole moments, and flavor violating dipole moments, such as and , is quite different from that in the MSSM. From general analytic considerations, we derive bounds on the fractional sneutrino mass splittings , and the fractional charged slepton splittings . For , the mixing is allowed to be maximal. We also comment on the magnitudes and correlations between CP-violating angles coming from electric dipole moments. We supplement the analytical considerations by detailed numerical calculations. Received: 6 September 2001 / Revised version: 30 October 2001 / Published online: 7 December 2001     

Supersymmetric enhancement factor for the 1-jet cross-section inp - \bar p reactions

We compare the 1-jet inclusive cross-section at highp _⊥ in proton-antiproton reaction atSPS collider predicted by standard QCD and by its simplest supersymmetric extension (SQCD). We first compute the total enhancement factorK between QCD and SQCD jets as a function ofp _⊥. Then we compute the observable enhancement factor which is smaller thanK since the transverse momentum of supersymmetric particles is not fully observable. We have analyzed two cases (i)p _⊥ is small compared to the masses of squarks and only light gluinos (2 GeV) are considered (ii)p _⊥ is large compared to the masses of squarks (17 GeV in our analysis) and both gluinos and squarks are taken into account. The observable enhancement factor between QCD and SQCD is found to be small (of order 1.3 to 1.5 forp _⊥=100 GeV). Missingp _⊥ events with one ordinary jet and one jet due to the production of a supersymmetric particle are found to be non negligible with respect to those with two supersymmetric jets. We also display some interesting supersymmetric relations among parton cross-sections.     

The determination of theW anomalous magnetic moment inp\bar p \to W\gamma X

We investigate the possibilities of measuring theW anomalous magnetic moment parameter, κ, in the reaction \(p\bar p \to W\gamma X\) . We present a calculation of the κ dependence of the total cross-section, the lab frame angular differential cross-section, the invariant mass distribution and the angular distribution of the decay lepton. We conclude that it will be extremely difficult to measure κ at the CERN collider (even after an upgrade to 700 GeV total cm energy) but that it may be feasible at the FNAL Tevatron.     

Cross sections and mean charges of jets inp\bar p collisions

Two jet reactions at collider energies within the frame of QCD are studied. Cross sections and mean charges are shown for both cases when one or two jets are observed. Scaling violations are introduced by means of the Altarelli-Parisi equation for a completely asymmetric sea. The effects due to scaling violation, gluon distribution and gluons in the final state are computed.     

\bar v_e e^ - -Annihilation and supersymmetric particles

In the framework of a minimal supersymmetric (s) extension of the standard Glashow-Weinberg-Salam theory, creation of s-partners of known leptons and gauge bosons in the -annihilation is studied. The angle distributions and total cross sections of s-particle creation are investigated in detail. The comparison with similar processes with the participation of known particles is performed. The possibility of an experimental identification of s-particles in the -annihilation is analyzed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 10, pp. 68–74, October, 1989.The authors thank I. M. Zheleznykh for useful discussions.     

A supersymmetric left-right confining model of the weak interactions

We extend the supersymmetric, confining theory of weak interactions to a left-right symmetric model. This model is based on the gauge group SU(M)_SC×SU(2)_R×SU(2)_L×SU(3)_c×U(1) and is more natural as far as supersymmetry breaking is concerned. Supersymmetry protects chiral symmetries from spontaneous breakdown and allows a solution to the strong CP problem. This model can accommodate at most three generations of quarks and leptons.     

B^0 - \bar B^0 mixing in a supersymmetric model without at-quark

A model based on a low energySU(3)_c×SU(2)₁×SU(2)₂×U(1) _H gauge group is considered. Theb-quark couples mainly to thec-quark via a new heavyW-boson and thet-quark is omitted altogether. The model is shown to be compatible with low energy charged current data. \(B_d^0 - \bar B_d^0 \) mixing occurs through the exchange of the heavyW-boson and through gluino exchange in the supersymmetric version of the model. The calculated mixing is much smaller in both cases than the observed effect and the model is, therefore, ruled out.     

The influence of Bose-Einstein correlations on intermittency inp\bar p collisions at\sqrt s = 630 GeV

The influence of Bose-Einstein correlations on the rise of factorial moments is small in the 1-dimensional phase space given by the pseudorapidity η, where the 2-body correlation function is dominated by unlike-sign particle correlations. Contraily, the influence is dominant in the higher dimensional phase space. This is shown by using correlation integrals. They exhibit clear power law dependences on the four-momentum transferQ ² for all orders investigated (i=2–5). When searching for the origin of this behaviour, we found that the Bose-Einstein ratio itself shows a steep rise forQ ²→0, compatible with a power law.