abstract

The upgraded CDF detector is now collecting data with the aim of integrating 2 fb\(^{-1}\) by year 2005. The pursued \(B\) physics program is very appealing. CDF will provide measurements of various CP violating and \(B\) mixing parameters which both complement and extend \(B\)-factories measurements. In addition there is a variety of spectroscopy measurements on \(B_s\) and heavier \(B\) hadrons which are currently accessible only at the Tevatron. In this talk we give a description of the new CDF tools available for \(B\) physics, we discuss the preliminary results obtained with the first 70 pb\(^{-1}\) of data, and we highlight Run II \(B\) physics prospects.

abstract

Present status of the NNLO QCD calculations of the rare decays \(\bar {B} \to X_s l^{\,+} l^{\,-}\) and \(\bar {B} \to X_s \gamma \) is summarized.

abstract

We calculate the contribution to the \(B\to \pi \pi \) decay from gluonic penguin operator, \(O_{8g}\), including both hard \(O(\alpha _{\rm s})\) and soft gluon effects. As expected, the soft effects enter at order \(1/m_b^2\), but are numerically of the same order as the hard ones, indicating the necessity of taking them into account.

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We discuss the origin and phenomenological consequences of the flavour violating couplings of the neutral Higgs bosons to the down-type quarks generated in the minimal supersymmetric standard model (MSSM) for large values of \(\tan \,\beta \). We concentrate on the scenario with minimal flavour and CP violation (MFV) and demonstrate the tight correlation of the \(B^0_s\)–\(\bar B^0_s\) mass difference with BR\((B^0_s\rightarrow \mu ^{\,+}\mu ^{\,-})\) and BR\((B^0_{d}\rightarrow \mu ^{\,+}\mu ^{\,-})\). While the first correlation holds also in the case of non-minimal flavour violation, the second one is specific for the minimal case and can potentially serve as a test of the sources of flavour violation in supersymmetry.

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We present the results of an effective approach to rescattering in \(B\) decays to two pseudoscalar mesons, where all inelastic Zweig-rule-satisfying SU(3)-symmetric final-state interactions are taken into account. It is shown how such rescattering corrections lead to a simple redefinition of the amplitudes, permitting the use of a simple diagram-based description, in which, however, weak phases may enter in a modified way. An estimate of how these modifications might affect the extracted value of unitarity triangle angle \(\gamma \) is given. It is pointed out that substantial shifts in the value of \(\gamma \) cannot be excluded on the basis of the low experimental bound on the \(B^0_d \to K^{\,+}K^{\,-}\) branching ratio alone.

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I discuss mechanisms of heavy quark production in (real) photon–nucleon and (real) photon–(real) photon collisions. In particular, I focus on application of the Saturation Model. In addition to the main dipole–nucleon or dipole–dipole contribution included in recent analyses, I propose how to calculate within the same formalism the hadronic single-resolved contribution to heavy quark production. At high photon–photon energies this yields a sizeable correction of about 30–40% for inclusive charm production and 15–20% for bottom production. Adding all possible contributions to \(e^+ e^- \rightarrow b \bar b X\) together removes a huge deficit observed in earlier works but does not solve the problem totally.

abstract

Measurements of the top quark mass and the \(t\bar {t}\) and single top production cross sections, obtained by CDF and D0 Collaboration at the Tevatron, are presented. The methodology of CDF and D0 top quark analyses and their underlying assumptions are summarized. The CDF and D0 top mass averages, based on about 100 pb\(^{-1}\) of data from collisions of \(p\bar {p}\) at \(\sqrt {s}\) = 1.8 TeV collected by each experiment in Run-I, and obtained from measurements in several channels, are \(M_{\rm t}=176.1\pm 4.0\ ({\rm stat}) \pm 5.1\ ({\rm syst})\) GeV/\(c^2\) and \(M_{\rm t}=172.1\pm 5.2\ ({\rm stat}) \pm 4.9\,({\rm syst)\,GeV}/c^2\), respectively. The combined Tevatron top quark mass is \(M_{\rm t}\!=\!174.3 \pm 3.2\,({\rm stat}) \pm 4.0\)  (syst) GeV/\(c^2\). The CDF measurement of the \(t\bar {t}\) cross section (assuming \(M_{\rm t}=175\) GeV/\(c^2\)) is \(\sigma _{tt}=6.5 \pm ^{1.7}_{1.4}\) pb, and the D0 value (assuming \(M_{\rm t}=172.1\) GeV/\(c^2\)) is \(\sigma _{tt}=5.9\pm 1.7\) pb. In anticipation of the increased amount of data in Run-II, prospects are presented. The fact that top quark analyses are among the best windows to new physics beyond the Standard Model is emphasized.

abstract

We discuss the spin properties of top quark pairs produced at hadron colliders at next-to-leading order in the coupling constant \(\alpha _{\rm s}\) of the strong interaction. Specifically we present, for some decay channels, results for differential angular distributions that are sensitive to \(t\bar t\) spin correlations.

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I give an introduction to the effective field theory description of top pair production at threshold in \(e^+e^-\) annihilation. The impact of the summation of logarithms of the top quark velocity including most recent results at next-to-next-to-leading order is discussed.

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Some features of a program eett6f for top quark pair production and decay into six fermions at linear colliders are discussed. Lowest order standard model predictions for cross sections of some six fermion channels and for the top quark decay width are confronted with the predictions obtained within a model with an anomalous \(Wtb\) coupling. The question of whether non doubly resonant background can easily be reduced by imposing kinematical cuts is addressed.

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Once heavy-quark corrections are take into account \(\nu p\) elastic scattering provides a complementary probe of polarized strangeness in the nucleon to measurements from inclusive and semi-inclusive polarized deep inelastic scattering. We review the different types of experiment and a recent NLO calculation of heavy-quark contributions to the weak neutral-current axial-charge (measurable in \(\nu p\) elastic scattering) performed using Witten’s heavy-quark renormalization group method.

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We study the simplest Two-Higgs-Doublet Model that allows for CP nonconservation, where it can be parametrized by only one parameter in the Higgs potential. Different concepts of maximal CP-nonconservation in the gauge-Higgs and the quark-Higgs (Yukawa) sectors are compared. Maximal CP nonconservation in the gauge-Higgs sector does normally not lead to maximal CP nonconservation in the Yukawa sector, and vice versa.

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We show how the transverse \(\tau ^{+}\tau ^{-}\) spin correlations can be used to measure the parity of the Higgs boson and hence to distinguish a CP-even \(H\) boson from CP-odd \(A^{0}\) in the future high energy accelerator experiments. We investigate the subsequent decays of the \(\tau ^{\pm }\) into \(\pi ^{\pm }\bar {\nu }_{\tau }(\nu _{\tau })\) and \(\rho ^{\pm }\bar {\nu }_{\tau }(\nu _{\tau })\). The prospects for the measurement of the Higgs boson parity with a mass of \(120\) GeV are quantified for the case of \(e^{+}e^{-}\) collisions of \(500\) GeV center of mass energy. The Standard Model Higgsstrahlung production process is used as an example.

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Using the SANC system we study the one-loop electroweak standard model predictions, including virtual and real photon emission, for the decays of the on-shell vector boson, \(W \to l {\nu _l} (\gamma )\). The complete one-loop corrections and exact photon emission matrix element are taken into account. For the phase–space integration, the Monte Carlo technique is used. This provides a useful element, first for the evaluation of the theoretical uncertainty of PHOTOS. Later we analyse the source of the differences between SANC and PHOTOS and we calculate the additional weight, which once installed, improves predictions of PHOTOS simulations. We can conclude that, after the correction of the weight is implemented, the theoretical uncertainty of PHOTOS simulations due to an incomplete first-order matrix element is reduced to below \(\frac {\alpha }{\pi }\), for observables not tagging the photon in a direct way, and to 10% otherwise. This is interesting for applications in the phenomenology of the ongoing LEP2 and future LC and LHC experimental studies.

abstract

New results on the low energy \(e^+e^-\) annihilation into hadrons from Novosibirsk and Beijing are described. The validity of the CVC relation between \(e^+e^-\) and \(\tau \) decays is considered. Implications of the new measurements for the evaluation of the hadronic contribution to the muon anomalous magnetic moment are discussed.