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TTP01-39 Results on N(1232) resonance parameters: A new pi N partial wave analysis
Gerhard H„ohler
D. Drexel and L. Tiator (eds
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TTP01-38 Precision Pion-Proton Elastic Differential Cross Sections at Energies Spanning the Delta Resonance

TTP01-38 Precision Pion-Proton Elastic Differential Cross Sections at Energies Spanning the Delta Resonance

A precision measurement of absolute pi+p and pi-p elastic differential cross sections at incident pion laboratory kinetic energies from T_pi = 141.15 to 267.3 MeV is described. Data were obtained detecting the scattered pion and recoil proton in coincidence at 12 laboratory pion angles from 55 to 155 degrees for pi+p, and six angles from 60 to 155 degrees for pi-p. Single arm measurements were also obtained for pi+p energies up to 218.1 MeV, with the scattered pi+ detected at six angles from 20 to 70 degrees. A flat-walled, super-cooled liquid hydrogen target as well as solid CH2 targets were used. The data are characterized by small uncertainties, ~1-2% statistical and ~1-1.5% normalization. The reliability of the cross section results was ensured by carrying out the measurements under a variety of experimental conditions to identify and quantify the sources of instrumental uncertainty. Our lowest and highest energy data are consistent with overlapping results from TRIUMF and LAMPF. In general, the Virginia Polytechnic Institute SM95 partial wave analysis solution describes our data well, but the older Karlsruhe-Helsinki PWA solution KH80 does not.

M.M. Pavan, Hans-Martin Staudenmaier & al.
Phys. Rev. C 64 064611 2001
PDF PostScript arXiv

TTP01-37 Measurement of neutron detection efficiencies in NaI using the Crystal Ball detector

TTP01-37 Measurement of neutron detection efficiencies in NaI using the Crystal Ball detector

We report on a measurement of the neutron detection efficiency in NaI crystals in the Crystal Ball (CB) detector obtained from a study of pi- p to pi0 n reactions at the Brookhaven National Laboratory AGS. A companion GEANT-based Monte Carlo study has been done to simulate these reactions in the CB, and a comparison with the data is provided.

T.D.S. Stanislaus, Hans-Martin Staudenmaier & al.
Nucl. Instrum. Meth. A 462 463-473 2001
PDF PostScript

TTP01-36 Determination of the Quadratic Slope Parameter in eta to 3 pi0 Decay

TTP01-36 Determination of the Quadratic Slope Parameter in eta to 3 pi0 Decay

We have determined the quadratic slope parameter alpha for eta to 3 pi0 to be alpha = -0.031(4) from a 99% pure sample of 10^6 eta to 3 pi0 decays produced in the reaction pi- p to n eta close to the eta threshold using the Crystal Ball detector at the AGS. The result is four times more precise than the present world data and disagrees with current chiral perturbation theory calculations by about four standard deviations.

W. B. Tippens, Hans-Martin Staudenmaier & al.
Phys. Rev. Lett. 87 192001 2001
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TTP01-35 Measurement of K- p to eta Lambda near threshold

TTP01-35 Measurement of K- p to eta Lambda near threshold

We present measurements of the differential and total cross sections and the Lambda polarization for the reaction K- p to eta Lambda from threshold to pK- = 770 MeV/c, with much better precision than previous measurements. Our cross-section data show a remarkable similarity to the SU(3) flavor-related pi- p to eta n cross-section results. The reaction K- p to eta Lambda at threshold is dominated by formation of the intermediate Lambda(1670)1/2- state.

A. Starostin, Hans-Martin Staudenmaier & al.
Phys. Rev. C 64 055205 2001
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TTP01-34 Reparametrization Invariance in Inclusive Decays of Heavy Hadrons

TTP01-34 Reparametrization Invariance in Inclusive Decays of Heavy Hadrons

Reparametrization invariance is the invariance of the heavy mass limit under small changes of the heavy-quark four velocity. We discuss the implications of this invariance for non-local light cone operators, the matrix elements of which are relevant for the leading and subleading shape functions describing differential rates for inclusive heavy-to-light transitions.

Francisco Campanario and Thomas Mannel
PDF PostScript

TTP01-33 Direct CP Violation in Radiative B Decays

TTP01-33 Direct CP Violation in Radiative B Decays

We discuss the role of the radiative $B$ decays $B \rightarrow X_{s/d} \, \gamma$ in our search for new physics focusing on the issue of direct CP violation. We discuss in some detail a SM prediction for the CP asymmetries in inclusive $b \rightarrow s/d$ transitions, namely $|\Delta {\cal B}(B \to X_s \gamma) + \Delta {\cal B}(B \to X_d \gamma) \sim 1 \cdot 10^{-9}|$. Any measured value in significant deviation of this estimate would indicate new sources of $CP$ violation beyond the CKM phase

Tobias Hurth and Thomas Mannel
PDF PostScript

TTP01-32 Radiative return at NLO and the measurement of the hadronic cross-section in electron positron annihilation

TTP01-32 Radiative return at NLO and the measurement of the hadronic cross-section in electron positron annihilation

Electron-positron annihilation into hadrons plus an energetic photon from initial state radiation allows the hadronic cross-section to be measured over a wide range of energies. The full next-to-leading order QED corrections for the cross-section for e^+ e^- annihilation into a real tagged photon and a virtual photon converting into hadrons are calculated where the tagged photon is radiated off the initial electron or positron. This includes virtual and soft photon corrections to the process e^+ e^- \to \gamma +\gamma^* and the emission of two real hard photons: e^+ e^- \to \gamma + \gamma + \gamma^*. A Monte Carlo generator has been constructed, which incorporates these corrections and simulates the production of two charged pions or muons plus one or two photons. Predictions are presented for centre-of-mass energies between 1 and 10 GeV, corresponding to the energies of DAPHNE, CLEO-C and B-meson factories.

G. Rodrigo, H. Czyz, J.H. K„uhn, M. Szopa
Eur.Phys.J. C24 71-82 2002
PDF PostScript arXiv

TTP01-31 Top quark pair production and decay including spin effects at hadron colliders: Predictions at NLO QCD

TTP01-31 Top quark pair production and decay including spin effects at hadron colliders: Predictions at NLO QCD

Top quark-antiquark (t tbar) pairs will be produced copiously at the Tevatron collider and in huge numbers at the LHC. This will make possible detailed investigations of the properties and interactions of this quark flavor. The analysis and interpretation of future data requires precise predictions of the hadronic production of ttbar pairs and of their subsequent decays. In this talk the reactions p pbar, p p –> t tbar X –> l^+l^-X are considered and results are presented of our calculation of the dilepton angular distribution at next-to-leading order QCD, keeping the full dependence on the spins of the intermediate t tbar state. The angular distribution is determined for different choices of reference axes that can be identified with the t and tbar spin axes. While the QCD corrections to the leading-order distribution turn out to be small in the case of the LHC, we find them to be sizeable in the case of the Tevatron and find, moreover, the angular distribution to be sensitive to the parton content of the proton.

W. Bernreuther, A. Brandenburg, Z. G. Si, P. Uwer
Int.J.Mod.Phys. A18 1357-1364 2003
PDF PostScript arXiv

TTP01-30 Counting contact terms in $B \to V \gamma$ decays

TTP01-30 Counting contact terms in $B \to V \gamma$ decays

We clarify the origin and cancellation of contact terms in the weak annihilation amplitudes contributing to $B\to V \gamma$. It is demonstrated that the photon emission from the final-state quarks vanishes in the chiral limit of massless quarks. The contact terms in the QCD light-cone sum rule evaluation of the weak annihilation amplitudes are also discussed.

Alexander Khodjamirian and Daniel Wyler
in a volume „From Integrable Models to Gauge Theories“, in honor of Sergei Matinyan, edited by V. G. Gurzadyan and A. G. Sedrakian, World Scientific, Singapore, 2002
PDF PostScript arXiv

TTP01-29 Steps towards the QCD calculation for e+ e- –

TTP01-29 Steps towards the QCD calculation for e+ e- –

3 jets at NNLO > High precision analyses of experimental data for e+ e- annihillation, such as determination of jet rates or event shape observables, call for complete

      next-to-next-to-leading order (NNLO) perturbative QCD predictions. In this talk, we discuss the various ingredients entering the calculation of the NNLO corrections
      in e+ e- annihillation. 
Sven Moch, Peter Uwer, Stefan Weinzierl
Budapest 2001, High energy physics hep2001/004 (2001)
PDF PostScript arXiv

TTP01-28 Duality in Semi-Exclusive Processes

TTP01-28 Duality in Semi-Exclusive Processes

Semi-exclusive processes like $\gamma p \to \pi^+ Y$ are closely analogous to DIS, $ep \to eX$, in the limit where the momentum transfer $|t|$ to the pion and the mass of the inclusive system $Y$ are large but still much smaller than the total CM energy. We apply Bloom-Gilman duality to this semi-exclusive process. The energy dependence of the $\gamma p \to \pi^+ n$ cross section given by semi-local duality agrees with data for moderate values of $|t|$, but its normalization is underestimated by about two orders of magnitude. This indicates that rather high momentum transfers are required for the validity of PQCD in the hard subprocess $\gamma u \to \pi^+ d$. In the case of Compton scattering $\gamma p \to \gamma p$ the analogous discrepancy is about one order of magnitude. In electroproduction the virtuality of the incoming photon can be used to directly measure the hardness of the subprocess.

Patrik Eden, Paul Hoyer and Alexander Khodjamirian
JHEP 0110:040 1-7 2001
PDF PostScript arXiv

TTP01-27 Next-to-leading-log renormalization-group running in heavy-quarkonium creation and annihilation

TTP01-27 Next-to-leading-log renormalization-group running in heavy-quarkonium creation and annihilation

In the framework of potential NRQCD, we obtain the next-to-leading-log renormalization-group running of the matching coefficients for the heavy quarkonium production currents near threshold. This allows to obtain S-wave heavy-quarkonium production/annihilation observables with next-to-leading-log accuracy within perturbative QCD. In particular, we give expressions for the decays of heavy quarkonium to e^+e^- and to two photons.

Antonio Pineda
Phys. Rev. D66 054022 2002
PDF PostScript arXiv

TTP01-26 Radiative return at NLO and the measurement of the hadronic cross section

TTP01-26 Radiative return at NLO and the measurement of the hadronic cross section

The measurement of the hadronic cross-section in $e^+ e^-$ annihilation at high luminosity factories using the radiative return method is motivated and discussed. A Monte Carlo generator which simulates the radiative process $e^+ e^- \to \gamma+hadrons$ at the next-to-leading order accuracy is presented. The analysis is then extended to the description of events with hard photons radiated at very small angle.

German Rodrigo
Acta Phys. Polon. B32 3833-3844 2001
PDF PostScript arXiv

TTP01-25 Nested Sums, Expansion of Transcendental Functions and Multi-Scale Multi-Loop Integrals

TTP01-25 Nested Sums, Expansion of Transcendental Functions and Multi-Scale Multi-Loop Integrals

Expansion of higher transcendental functions in a small parameter are needed in

   many areas of science. For certain classes of functions this can be achieved by
   algebraic means. These algebraic tools are based on nested sums and can be
   formulated as algorithms suitable for an implementation on a computer. Examples,
   such as expansions of generalized hypergeometric functions or Appell functions are
   discussed. As a further application, we give the general solution of a two-loop integral,
   the so-called C-topology, in terms of multiple nested sums. In addition, we discuss
   some important properties of nested sums, in particular we show that they satisfy a
   Hopf algebra.
Sven Moch, Peter Uwer, Stefan Weinzierl
J.Math.Phys. 43 3363 2002
PDF PostScript arXiv

TTP01-24 Non-perturbative effects in semi-leptonic B_c decays

TTP01-24 Non-perturbative effects in semi-leptonic B_c decays

We discuss the impact of the soft degrees of freedom inside the B_c meson on its rate in the semi-leptonic decay B_c → X l nu_l where X denotes light hadrons below the D^0 threshold. In particular we identify contributions involving soft hadrons which are non-vanishing in the limit of massless leptons. These contributions become relevant for a measurement of the purely leptonic B_c decay rate, which due to helicity suppression involves a factor m_l^2 and thus is much smaller than the contributions involving soft hadrons.

T. Mannel, S. Wolf
Phys. Rev. D65 074012 2002
PDF PostScript arXiv

TTP01-23 The next-to-next-to-leading Order QCD Corrections to the Photon Structure Functions

TTP01-23 The next-to-next-to-leading Order QCD Corrections to the Photon Structure Functions

The next-to-next-to-leading order (NNLO) corrections in massless perturbative QCD are derived for the parton distributions of the photon and the deep inelastic structure functions F_1^gamma and F_2^gamma. We present the full photonic coefficient functions at order alpha alpha_s and calculate the first six even-integer moments of the corresponding O(alpha alpha_s^2) photon-quark and photon-gluon splitting functions together with the moments of the alpha alpha_s^2 coefficient functions which enter only beyond NNLO. These results are employed to construct parametrizations of the splitting functions which prove to be sufficiently accurate at least for momentum fractions x >= 0.05. We also present explicit expressions for the transformation from the MS_bar to the DIS_gamma factorization scheme and write down the solution of the evolution equations. The numerical impact of the NNLO corrections is discussed in both schemes.

S. Moch, J.A.M. Vermaseren and A. Vogt
Nucl.Phys. B621 (2002) 413
PDF PostScript arXiv

TTP01-22 Renormalization group improvement of the NRQCD Lagrangian and heavy quarkonium spectrum

TTP01-22 Renormalization group improvement of the NRQCD Lagrangian and heavy quarkonium spectrum

We complete the leading-log renormalization group scaling of the NRQCD Lagrangian at $O(1/m^2)$. The next-to-next-to-leading-log renormalization group scaling of the potential NRQCD Lagrangian (as far as the singlet is concerned) is also obtained in the situation $m\alpha_s \gg \Lambda_{QCD}$. As a by-product, we obtain the heavy quarkonium spectrum with the same accuracy in the situation $m\alpha_s^2 \simg \Lambda_{QCD}$. When $\Lambda_{QCD} \ll m\alpha_s^2$, this is equivalent to obtain the whole set of $O(m\alpha_s^{(n+4)} \ln^n \alpha_s)$ terms in the heavy quarkonium spectrum. The implications of our results in the non-perturbative situation $m\alpha_s \sim \Lambda_{QCD}$ are also mentioned.

Antonio Pineda
Phys. Rev. D 65 074007 2002
PDF PostScript arXiv

TTP01-21 Determination of $\alpha_s$ and heavy quark masses from recent measurements of $R(s)$

TTP01-21 Determination of $\alpha_s$ and heavy quark masses from recent measurements of $R(s)$

In this paper we compare recent experimental data for the total cross section $\sigma(e^+e^-\to\mbox{hadrons})$ with the up-to-date theoretical prediction of perturbative QCD for those energies where perturbation theory is reliable. The excellent agreement suggests the determination of the strong coupling $\alpha_s$ from the measurements in the continuum. The precise data from the charm threshold region, when combined with the recent evaluation of moments with three loop accurracy, lead to a direct determination of the short distance $\overline{\rm MS}$ charm quark mass. Our result for the strong coupling constant $\alpha_s^{(4)}(5~\mbox{GeV})=0.235^{+0.047}_{-0.047}$ corresponds to $\alpha_s^{(5)}(M_Z)=0.124^{+0.011}_{-0.014}$, for the charmed quark mass we find $m_c(m_c)=1.304(27)$. Applying the same approach to the bottom quark we obtain $m_b(m_b)=4.191(51)$~GeV. Whereas our result for $\alpha_s(M_Z)$ serves as a useful cross check for other more precise determinations, our values for the charm and bottom quark masses are more accurate than other recent analyses.

J.H. K\„uhn and M. Steinhauser
PDF PostScript arXiv

TTP01-20 Rigorous new predictions for inclusive heavy quarkonium P-wave decays

TTP01-20 Rigorous new predictions for inclusive heavy quarkonium P-wave decays

We show that some NRQCD colour-octet matrix elements can be written in terms of (derivatives of) wave functions at the origin and non-perturbative universal constants once the factorization between the soft and ultrasoft scale is achieved by using an effective field theory where only ultrasoft degrees of freedom are kept as dynamical entities. This allows us to derive a new set of relations between inclusive heavy-quarkonium P-wave decays into light hadrons with different principal quantum number and with different heavy flavour. In particular, we can estimate the branching ratios of bottomonium P-wave states by using charmonium data.

Nora Brambilla, Dolors Eiras, Antonio Pineda, Joan Soto and Antonio Vairo
Phys. Rev. Lett. 88 012003 2002
PDF PostScript arXiv

TTP01-19 The Cross Section of e^+ e^- Annihilation into Hadrons of Order alpha_s^4 n_f^2 in Perturbative QCD

TTP01-19 The Cross Section of e^+ e^- Annihilation into Hadrons of Order alpha_s^4 n_f^2 in Perturbative QCD

We present the first genuine QCD five-loop calculation of the vacuum polarization functions: analytical terms of order alpha_s^4 n_f^2 to the absorptive parts of vector and scalar correlators. These corrections form an important gauge-invariant subset of the full O(alpha_s^4) correction to $e^+ e^- annihilation into hadrons and the Higgs decay rate into hadrons respectively. They discriminate between different widely used estimates of the full result.

P.A. Baikov, K.G. Chetyrkin and J.H. K\„uhn
Phys. Rev. Lett. 88 012001-012004 2002
PDF PostScript arXiv

TTP01-18 Developments in Deep-inelastic Structure Function Calculations

TTP01-18 Developments in Deep-inelastic Structure Function Calculations

We review recent developments in the calculation of deep-inelastic structure functions to next-to-next-to leading order in perturbative QCD. We discuss the impact of these corrections on the determination of the strong coupling alpha_s and the parton distributions.

S. Moch, J.A.M. Vermaseren and M. Zhou
JHEP Proc. hep2001
PDF PostScript arXiv

TTP01-17 Large order behavior in perturbation theory of the pole mass and the singlet static potential

TTP01-17 Large order behavior in perturbation theory of the pole mass and the singlet static potential

We discuss upon recent progress in our knowledge of the large order behavior in perturbation theory of the pole mass and the singlet static potential. We also discuss about the renormalon subtracted scheme, a matching scheme between QCD and any effective field theory with heavy quarks where, besides the usual perturbative matching, the first renormalon in the Borel plane of the pole mass is subtracted.

Antonio Pineda
AIP Conf.Proc. 602 265-270 2001
PDF PostScript arXiv

TTP01-16 Top Quark Spin Correlations at Hadron Colliders: Predictions at Next-to-Leading Order QCD

TTP01-16 Top Quark Spin Correlations at Hadron Colliders: Predictions at Next-to-Leading Order QCD

The collider experiments at the Tevatron and the LHC will allow for detailed

   investigations of the properties of the top quark. This requires precise predictions of
   the hadronic production of $t\bar t$ pairs and of their subsequent decays. In this
   Letter we present for the reactions $p {\bar p}, p p \to t{\bar t} + X \to \ell^+\ell'^-X$
   the first calculation of the dilepton angular distribution at next-to-leading order
   (NLO) in the QCD coupling, keeping the full dependence on the spins of the
   intermediate $t\bar{t}$ state. The angular distribution reflects the degree of
   correlation of the $t$ and $\bar t$ spins which we determine for different choices of
   $t$ and $\bar t$ spin bases. In the case of the Tevatron, the QCD corrections are
   sizeable, and the distribution is quite sensitive to the parton content of the proton.
W. Bernreuther, A. Brandenburg, Z. G. Si, P. Uwer
Phys. Rev. Lett. 87 242002 2001
PDF PostScript arXiv

TTP01-15 Next-to-Next-to-Leading Logarithms in Four-Fermion Electroweak Processes at High Energy

TTP01-15 Next-to-Next-to-Leading Logarithms in Four-Fermion Electroweak Processes at High Energy

We sum up the next-to-next-to-leading logarithmic virtual electroweak corrections to the high energy asymptotics of the neutral current four-fermion processes for light fermions to all orders in the coupling constants using the evolution equation approach. From this all order result we derive finite order expressions through next-to-next-to leading order for the total cross section and various asymmetries. We observe an amazing cancellation between the sizable leading, next-to-leading and next-to-next-to-leading logarithmic contributions at TeV energies.

J.H.~K\„uhn, S.~Moch, A.A.~Penin, V.A.~Smirnov
Nucl. Phys. B616 286-306 2001
PDF PostScript arXiv

TTP01-14 Non-diagonal current correlators at order alpha_s^2 in QCD and HQET

TTP01-14 Non-diagonal current correlators at order alpha_s^2 in QCD and HQET

The non-diagonal correlators of vector and scalar currents are considered at three-loop order in QCD. The full mass dependence is computed in the case where one of the quarks is massless and the other one carries mass $M$. We exploit the decoupling relations between the full theory and the heavy quark effective theory (HQET) in order to obtain the logarithmic parts of the leading threshold terms. With the help of conformal mapping and Pad\'e approximation numerical estimates for the non-logarithmic terms are extracted which in turn lead to a prediction of the correlator in HQET at order $\alpha_s^2$. As applications of the vector and scalar correlator we consider the single-top-quark production via the process $q\bar{q}\to t\bar{b}$ and the decay rate of a charged Higgs boson into hadrons, respectively. In both cases the computed NLO corrections are shown to be numerically much less important than the leading ones. On the contrary, the NLO order QCD corrections to the HQET sum rule for the leptonic decay rate of a heavy-light meson proves to be comparable to the leading one.

K.G. Chetyrkin and M. Steinhauser
Eur. Phys.J. C 21 319-338 2001
PDF PostScript arXiv Programs and Data

TTP01-13 NLO QED corrections to ISR in $e^+ e^-$ annihilation and the measurement of $\sigma(e^+ e^- \rightarrow hadrons)$ using tagged photons

TTP01-13 NLO QED corrections to ISR in $e^+ e^-$ annihilation and the measurement of $\sigma(e^+ e^- \rightarrow hadrons)$ using tagged photons

The leptonic tensor for the process $e^+ e^- \rightarrow \gamma+\gamma^*$, which describes the next-to-leading order virtual and soft QED corrections to initial state radiation in $e^+ e^-$ annihilation with emission of an extra virtual photon decaying into hadrons, is calculated. A Monte Carlo generator for the reaction $e^+ e^- \rightarrow \gamma + \pi^+ \pi^-$ has been set up which includes these corrections. It thus describes configurations where the for the reaction $e^+ e^- \rightarrow \gamma + \pi^+ \pi^-$ has been set up which includes these corrections. It thus describes configurations where the invariant mass of the hadrons plus photon is very close to $\sqrt{s}$. Predictions for cms energies of 1 to 10 GeV, corresponding to the energies of DAPHNE and B-meson factories, are presented. The possibility for an accurate measurement using tagged photons of $\sigma(e^+ e^- \rightarrow hadrons)$, which plays an important role in the theoretical description of the muon anomalous magnetic moment and the running of the electromagnetic coupling, is discussed.

G. Rodrigo, A. Gehrmann, M. Guilleaume and J. H. K\„uhn
Eur. Phys. J. C22 81-88 2001
PDF PostScript arXiv

TTP01-12 Determination of the bottom mass from the $\Upsilon(1S)$ system

TTP01-12 Determination of the bottom mass from the $\Upsilon(1S)$ system

We approximately compute the normalization constant of the first infrared renormalon of the pole mass (and the singlet static potential). Estimates of higher order terms in the perturbative relation between the pole mass and the $\MS$ mass (and in the relation between the singlet static potential and $\alpha_s$) are given. We define a matching scheme (the renormalon subtracted scheme) between QCD and any effective field theory with heavy quarks where, besides the usual perturbative matching, the first renormalon in the Borel plane of the pole mass is subtracted. A determination of the bottom $\MS$ quark mass from the $\Upsilon(1S)$ system is performed with this new scheme and the errors studied. Our result reads $m_{b,\MS}(m_{b,\MS})=4\,210^{+90}_{-90}({\rm theory})^{-25}_{+25}(\alpha_s)$ MeV. Using the mass difference between the $B$ and $D$ meson, we also obtain a value for the charm quark mass: $m_{c,\MS}(m_{c,\MS})=1\,210^{+70}_{-70}({\rm theory})^{+65}_{-65}(m_{b,\MS})^{-45}_{+45}(\lambda_1)$ MeV. We finally discuss upon eventual improvements of these determinations.

A. Pineda
JHEP 0106 022 2001
PDF PostScript arXiv

TTP01-11 Next-to-leading order QCD corrections to top quark spin correlations at hadron colliders: the reactions $gg\to t \bar t (g)$ and $gq(\bar q) \to t\bar t q (\bar q)$

TTP01-11 Next-to-leading order QCD corrections to top quark spin correlations at hadron colliders: the reactions $gg\to t \bar t (g)$ and $gq(\bar q) \to t\bar t q (\bar q)$

We have computed the cross section for $t\bar t$ production by gluon-gluon fusion at

   next-to-leading order (NLO) in the QCD coupling, keeping the full dependence on
   the $t\bar t$ spins. Furthermore we have determined to the same order the spin
   dependent cross sections for the processes $g + q ({\bar q})\to t {\bar t} + q ({\bar
   q})$. Together with our previous results for $q + {\bar q} \to t {\bar t} (g)$ these
   results allow for predictions, at NLO QCD, of the hadronic production of $t\bar t$
   pairs in a general spin configuration. As an application we have determined the degree
   of correlation of the $t$ and $\bar t$ spins at NLO, using various spin quantisation
   axes.
W. Bernreuther, A. Brandenburg, Z.G. Si, and P. Uwer
Phys.Lett. B509 53-58 2001
PDF PostScript arXiv

TTP01-10 Thirteen Years of Heavy Quark Expansion: Examples for its Progress and its Problems

TTP01-10 Thirteen Years of Heavy Quark Expansion: Examples for its Progress and its Problems

The heavy mass expansion has become a standard tool that has significantly evolved since its formulation about thirteen years ago. Some of the major results of the heavy mass expansion, namely the determination of $V_{cb}$ (both exclusive and inclusive) and lifetime calculations, are reviewed and some open problems are pointed out.

Thomas Mannel
Acta Phys. Polon. B32 1857-1868 2001
PDF PostScript
TTP01-09 Theoretical Aspects of b–>s gamma Transitions
Thomas Mannel
PDF PostScript

TTP01-08 CP Asymmetries in b–

TTP01-08 CP Asymmetries in b–

(s/d) gamma Transitions as a Test of CKM-CP Violation > We point out that a simple test of the mechanism of CP violation can be performed by a measurement of the CP asymmetries in exclusive and inclusive radiative rare decays. We show that the rate asymmetries \mbox{ $\Delta \Gamma = \Gamma(B^- \to f \gamma) - \Gamma(B^+ \to \bar{f} \gamma)$} for certain final states $f$ can be predicted in a theoretically clean way. Some implications for $b \to s \ell^+ \ell^-$ decays are discussed.

Tobias Hurth, Thomas Mannel
Phys. Lett. B511 196-202 2001
PDF PostScript arXiv

TTP01-07 Exploring new Physics in the $B \to \phi K$ System

TTP01-07 Exploring new Physics in the $B \to \phi K$ System

Employing the SU(2) isospin symmetry of strong interactions and estimates borrowed from effective field theory, we explore the impact of new physics on the decays $B^\pm\to \phi K^\pm$ and $B_d\to \phi K_S$ in a model-independent manner. To this end, we introduce - in addition to the usual mixing-induced CP asymmetry in $B_d\to \phi K_S$ - a set of three observables, which may not only provide smoking-gun signals for new-physics contributions to different isospin channels, but also valuable insights into hadron dynamics. Imposing dynamical hierarchies of amplitudes, we discuss various patterns of these observables, including also scenarios with small and large rescattering processes. Whereas the $B\to\phi K$ system provides, in general, a powerful tool to search for indications of new physics, there is also an unfortunate case, where such effects cannot be distinguished from those of the Standard Model.

Robert Fleischer, Thomas Mannel
Phys. Lett. B511 240-250 2001
PDF PostScript arXiv

TTP01-06 General Analysis of New Physics in $B \to J/\Psi K$

TTP01-06 General Analysis of New Physics in $B \to J/\Psi K$

We present a model-independent parametrization of the $B^\pm\to J/\psi K^\pm$, $B_d\to J/\psi K_S$ decay amplitudes by taking into account the constraints that are implied by the isospin symmetry of strong interactions. Employing estimates borrowed from effective field theory, we explore the impact of physics beyond the Standard Model and introduce – in addition to the usual mixing-induced CP asymmetry $A_{CP}^{mix}$ in $B_d\to J/\psi K_S$ – a set of three observables, allowing a general analysis of possible new-physics effects in the $B\to J/\psi K$ system. Imposing a dynamical hierarchy of amplitudes, we argue that one of these observables may already be accessible at the first-generation $B$-factories, whereas the remaining ones will probably be left for second-generation $B$ experiments. However, in the presence of large rescattering effects, all three new-physics observables may be sizeable. We also emphasize that a small value of $A_{CP}^{mix}$ could be due to new-physics effects arising at the $B\to J/\psi K$ decay-amplitude level. In order to establish such a scenario, the observables introduced in this paper play a key role.

R. Fleischer, T. Mannel
Phys. Lett. B506 311-322 2001
PDF PostScript arXiv

TTP01-05 The determination of $V_{ub}$ from inclusive semileptonic $B$ decays

TTP01-05 The determination of $V_{ub}$ from inclusive semileptonic $B$ decays

The hadronic mass distribution in semileptonic B-meson decays can be used for extracting the charmless part and thus determining the |V_ub/V_cb| ratio. We take into account first-order perturbative as well as non-perturbative QCD corrections. The sensitivity to model assumptions is studied and an estimate of the remaining uncertainties is performed.

M. Jezabek, T. Mannel, B. Postler, P Urban
Phys. Lett. B512 65-72 2001
PDF PostScript arXiv

TTP01-04 Progress on two-loop non-propagator integrals

TTP01-04 Progress on two-loop non-propagator integrals

At variance with fully inclusive quantities, which have been computed already at the two- or three-loop level, most exclusive observables are still known only at one loop, as further progress was hampered up to very recently

by the greater computational problems encountered in the study 

of multi-leg amplitudes beyond one loop. We discuss the progress made lately in the evaluation of two-loop multi-leg integrals, with particular emphasis on two-loop four-point functions.

T.Gehrmann, E.Remiddi
eConf C000911 (2001)
PDF PostScript arXiv

TTP01-03 Sudakov Resummation and Finite Order Expansions of Heavy Quark Hadroproduction Cross

TTP01-03 Sudakov Resummation and Finite Order Expansions of Heavy Quark Hadroproduction Cross

We resum Sudakov threshold enhancements in heavy quark

 hadroproduction for single-heavy quark inclusive and pair-inclusive
 kinematics.  We expand these resummed results and derive analytical
 finite-order cross sections through next-to-next-to-leading order.
 This involves the construction of next-to-leading order matching
 conditions in color space.  For the scale dependent terms we derive
 exact results using renormalization group methods. We study the
 effects of scale variations, scheme and kinematics choice on the
 partonic and hadronic cross sections, and provide estimates for top
 and bottom quark production cross sections.      
N. Kidonakis, E. Laenen, S. Moch, R. Vogt
Phys.Rev. D64 (2001) 114001
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TTP01-02 Polarized Beams and the Top Threshold

TTP01-02 Polarized Beams and the Top Threshold

The strong impact of longitudinally polarized electron and positron beams on precision studies of top quark production and decay close to the production threshold is demonstrated. The right-left asymmetry of the production cross section can be measured with a precision of one to two percent. The top quarks will be highly polarized which allows to measure the couplings responsible for the top quark decay. As characteristic examples the decay chains top –> bottom W(–> e + neutrino and top –> Higgs + bottom will be considered.

J.H. K„uhn
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TTP01-01 Measuring sigma(e+e- to hadrons) with Tagged Photons at Electron Positron Colliders

TTP01-01 Measuring sigma(e+e- to hadrons) with Tagged Photons at Electron Positron Colliders

A Monte Carlo generator has been constructed to simulate the reaction e+ e- –> gamma + 2 pions and gamma + 4 pions, where the photon is assumed to be observed in the detector. Predictions are presented for cms energies of 1GeV, 3GeV and 10GeV, corresponding to the energies of DAPHNE, BEBC and of B-meson factories. The event rates are sufficiently high to allow for a precise measurement of R(Q^2) in the region of Q between approximately 1GeV and 2.5GeV. Estimates for the kinematic breaking of isospin relations between different channels as a consequence of the mass difference between charged and neutral pions are given.

J.H. K„uhn
Nuc. Phys. B (Proc.Suppl.) 98 289-296 2001
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