Search

The search for Higgs bosons in both the standard model and its extensions is well under way at the Tevatron. As the integrated luminosity collected increases into the multiple inverse femptobarn range, these searches are becoming very interesting indeed. Meanwhile, the construction of the Large Hadron Collider (LHC) and its associated experiments at CERN are nearing completion. In this TeV4LHC workshop, it was realized that any experience at the Tevatron with respect to backgrounds, experimental techniques and theoretical calculations that can be verified at the Tevatron which have relevance for future measurements at the LHC were important. Studies and contributions to these efforts were made in three broad categories: theoretical calculations of Higgs production and decay mechanisms; theoretical calculations and discussions pertaining to non-standard model Higgs bosons; and experimental reviews, analyses and developments at both the Tevatron and the upcoming LHC experiments. All of these contributions represent real progress towards the elucidation of the mechanism of electroweak symmetry breaking., Comment: Editors: A. Dominguez, I. Iashvili, S. Willenbrock. Conference organizers: M. Carena, S. Mrenna

We calculate the Next-to-Leading Order (NLO) QCD corrections to W-b-bbar production including full bottom-quark mass effects. We study the impact of NLO QCD corrections on the total cross section and invariant mass distribution of the bottom-quark jet pair at the Fermilab Tevatron p-pbar collider. We perform a detailed comparison with a calculation that considers massless bottom quarks. We find that neglecting bottom-quark mass effects overestimates the NLO total cross-section for W-b-bbar production at the Tevatron by about 8% independent of the choice of renormalization and factorization scale., Comment: 16 pages, 13 figures, RevTeX4, 3 references and 2 figures added, published version

We review the status of the QCD corrected cross sections and kinematic distributions for the production of a Higgs boson in association with top quark or bottom quark pairs at the Fermilab Tevatron and at the LHC. Results for b-bbar-H production are presented in the Minimal Supersymmetric Model, where the rates can be greatly enhanced relative to the Standard Model rates. We place particular emphasis on theoretical uncertainties due to renormalization and factorization scale dependence and on the uncertainties coming from the Parton Distribution Functions., Comment: Contribution to the Tev4LHC Higgs Working Group Report

In these lectures I briefly review the Higgs mechanism of spontaneous symmetry breaking and focus on the most relevant aspects of the phenomenology of the Standard Model and of the Minimal Supersymmetric Standard Model Higgs bosons at both hadron and lepton colliders. Some emphasis is put on the perturbative calculation of both Higgs boson branching ratios and production cross sections, including the most important radiative corrections., Comment: 96 pages, 115 figures, RevTeX4

We review the present status of the QCD corrected cross sections and kinematic distributions for the production of a Higgs boson in association with bottom quarks at the Fermilab Tevatron and CERN Large Hadron Collider. Results are presented for the Minimal Supersymmetric Standard Model where, for large tan beta, these production modes can be greatly enhanced compared to the Standard Model case. The next-to-leading order QCD results are much less sensitive to the renormalization and factorization scales than the lowest order results, but have a significant dependence on the choice of the renormalization scheme for the bottom quark Yukawa coupling. We also investigate the uncertainties coming from the Parton Distribution Functions and find that these uncertainties can be comparable to the uncertainties from the remaining scale dependence of the next-to-leading order results. We present results separately for the different final states depending on the number of bottom quarks identified., Comment: 20 pages, Review submitted to Modern Physics Letters A

Physics at the Large Hadron Collider (LHC) and the International e+e- Linear Collider (ILC) will be complementary in many respects, as has been demonstrated at previous generations of hadron and lepton colliders. This report addresses the possible interplay between the LHC and ILC in testing the Standard Model and in discovering and determining the origin of new physics. Mutual benefits for the physics programme at both machines can occur both at the level of a combined interpretation of Hadron Collider and Linear Collider data and at the level of combined analyses of the data, where results obtained at one machine can directly influence the way analyses are carried out at the other machine. Topics under study comprise the physics of weak and strong electroweak symmetry breaking, supersymmetric models, new gauge theories, models with extra dimensions, and electroweak and QCD precision physics. The status of the work that has been carried out within the LHC / LC Study Group so far is summarised in this report. Possible topics for future studies are outlined., Comment: 472 pages, a version with high-resolution figures can be found at http://www.ippp.dur.ac.uk/~georg/lhclc/lhclcdoc.ps.gz

We present results for the production cross section of a Higgs Boson with a pair of bottom/anti-bottom quarks, including next-to-leading order (NLO) QCD corrections., Comment: 3 pages, 2 figures, uses ws-ijmpa.cls. Talk given by C.B. Jackson at the Meeting of the Division of Particles and Fields (DPF2004) in Riverside, CA, August 26-31, 2004

We present total rates and kinematic distributions for the associated production of a single bottom quark and a Higgs boson at the Tevatron and the LHC. We include next-to-leading order QCD corrections and compare the results obtained in the four and five flavor number schemes for parton distribution functions., Comment: 4 pages, 8 figures, RevTeX4

Theoretical progress in Higgs boson production and background processes is discussed with particular emphasis on QCD corrections at and beyond next-to-leading order as well as next-to-leading order electroweak corrections. The residual theoretical uncertainties of the investigated processes are estimated in detail. Moreover, recent investigations of the MSSM Higgs sector and other extensions of the SM Higgs sector are presented. The potential of the LHC and a high-energy linear e+e- collider for the measurement of Higgs couplings is analyzed., Comment: 169 pages, Proceedings 3rd Les Houches Workshop: Physics at TeV Colliders, Les Houches, France, 26 May - 6 Jun 2003

In the Standard Model, the coupling of the Higgs boson to b quarks is weak, leading to small cross sections for producing a Higgs boson in association with b quarks. However, Higgs bosons with enhanced couplings to b quarks, such as occur in supersymmetric models for large values of tan beta, will be copiously produced at both the Tevatron and the LHC in association with b quarks, which will be an important discovery channel. We investigate the connections between the production channels, bg -> bh and gg ->b bbar h, at next-to-leading order (NLO) in perturbative QCD and present results for the cases with two high p_T b jets and with one high p_T b jet at both the Tevatron the the LHC. Finally, the total cross sections without cuts are compared between gg -> b bbar h at NLO and b bbar ->h at NNLO., Comment: 7 pages, Contributed to 3rd Les Houches Workshop: Physics at TeV Colliders

The production of a Higgs boson in association with a pair of top-antitop or bottom-antibottom quarks plays a very important role at both the Tevatron and the Large Hadron Collider. The theoretical prediction of the corresponding cross sections has been improved by including the complete next-to-leading order QCD corrections. After a brief introduction, we review the results obtained for both the Tevatron and the Large Hadron Collider., Comment: 3 pages, 6 figures, uses svjour.cls. Talk given by L. Reina at the HEP2003 Europhysics Conference in Aachen, Germany (EPS 2003), July 17-23, 2003

The production of a Higgs boson in association with a pair of top-antitop or bottom-antibottom quarks plays a very important role at both the Tevatron and the Large Hadron Collider. The theoretical prediction of the corresponding cross sections has been improved by including the complete next-to-leading order QCD corrections. After a brief description of the most relevant technical aspects of the calculation, we review the results obtained for both the Tevatron and the Large Hadron Collider, Comment: 6 pages, 6 figures, espcrc2.sty. Talk given at the International Conference QCD03, 2-7 July 2003, Montpellier, France. To be published in Nucl. Phys. B Proc. Suppl

We present the next-to-leading order QCD corrected rate for the production of a scalar Higgs boson with a pair of high p_T bottom and anti-bottom quarks at the Tevatron and at the Large Hadron Collider. Results are given for both the Standard Model and the Minimal Supersymmetric Standard Model. The exclusive b-bbar-h production rate is small in the Standard Model, but it can be greatly enhanced in the Minimal Supersymmetric Standard Model for large tan(beta), making b-bbar-h an important discovery mode. We find that the next-to-leading order QCD results are much less sensitive to the renormalization and factorization scales than the lowest order results, but have a significant dependence on the choice of the renormalization scheme for the bottom quark Yukawa coupling., Comment: 27 pages, 17 figures, RevTeX4

The production of a Higgs boson in association with a pair of t-tbar quarks will play a very important role at both hadron and lepton colliders. We review the status of theoretical predictions and their relevance to Higgs boson studies, with particular emphasis on the recently calculated NLO QCD corrections to the inclusive cross section for p-pbar,pp -> t-tbar-h. We conclude by briefly discussing the case of exclusive b-bbar-h production and the potential of this process in revealing signals of new physics beyond the Standard Model., Comment: 6 pages, 4 figures, Talk given at the XXXVIII Rencontres de Moriond on Electroweak Interactions and Unified Theories, Les Arcs, France, March 15-22, 2003

We present in detail the calculation of the O(alpha_s^3) inclusive total cross section for the process pp -> t-tbar-h, in the Standard Model, at the CERN Large Hadron Collider with center-of-mass energy sqrt(s_H)=14 TeV. The calculation is based on the complete set of virtual and real O(alpha_s) corrections to the parton level processes q-qbar -> t-tbar-h and gg -> t-tbar-h, as well as the tree level processes (q,qbar)g -> t-tbar-h-(q,qbar). The virtual corrections involve the computation of pentagon diagrams with several internal and external massive particles, first encountered in this process. The real corrections are computed using both the single and the two cutoff phase space slicing method. The next-to-leading order QCD corrections significantly reduce the renormalization and factorization scale dependence of the Born cross section and moderately increase the Born cross section for values of the renormalization and factorization scales above m_t., Comment: 70 pages, 12 figures, RevTeX4: one word changed in the abstract, one sentence reworded in the introduction. To appear in Phys. Rev. D

We compute the O(alpha_s^3) inclusive cross section for the process pp -> t-tbar-h in the Standard Model, at sqrt(s)=14 TeV. The next-to-leading order corrections drastically reduce the renormalization and factorization scale dependence of the Born cross section and increase the total cross section for renormalization and factorization scales larger than m_t. These corrections have important implications for models of new physics involving the top quark., Comment: 5 pages, 4 figures, RevTeX4

We present the next-to-leading-order (NLO) QCD corrections to the inclusive total cross section for the production of a Higgs boson in association with a top anti-top quark pair within the Standard Model at the Tevatron and the LHC., Comment: LaTeX, 5 pages, 6 figures, talk given by L.R. at RADCOR2002/Loops and Legs, Kloster Banz, Germany, Sep. 2002, to appear in the Proceedings

We briefly present the status of QCD corrections to the inclusive total cross section for the production of a Higgs boson in association with a top-quark pair within the Standard Model at hadron colliders., Comment: 3 pages, talk given at 31st International Conference on High Energy Physics (ICHEP 2002), Amsterdam, The Netherlands, 24-31 Jul 2002

In this summary of the considerations of the QCD working group at Snowmass 2001, the roles of quantum chromodynamics in the Standard Model and in the search for new physics are reviewed, with empahsis on frontier areas in the field. We discuss the importance of, and prospects for, precision QCD in perturbative and lattice calculations. We describe new ideas in the analysis of parton distribution functions and jet structure, and review progress in small-$x$ and in polarization., Comment: Snowmass 2001. Revtex4, 34 pages, 4 figures, revised to include additional references on jets and lattice QCD

We emphasize the role that the associated production of a Higgs boson with a pair of top-antitop quarks can play at present and future hadron colliders. Results of recent calculations of the NLO total cross section for the associated production of a Standard Model like Higgs boson with a pair of top-antitop quarks at the Tevatron (sqrt(s)=2 TeV) are presented., Comment: 4 pages, 3 figures, uses RevTeX4. Contribution to Snowmass 2001

Future hadron colliders will have the potential to measure some of the most relevant Higgs boson couplings with high precision. In this paper we investigate the potential of a Very Large Hadron Collider (VLHC) to measure the top-quark Yukawa coupling., Comment: 6 pages, 9 figures, uses RevTeX4. Contribution to Snowmass 2001. Caption of Table I and conclusions expanded; one reference added

We present in detail the calculation of the O(alpha_s^3)inclusive total cross section for the process (p pbar-> t tbar h) in the Standard Model, at the Tevatron center-of-mass energy sqrt(s_H)=2 TeV. The next-to-leading order QCD corrections significantly reduce the renormalization and factorization scale dependence of the Born cross section. They slightly decrease or increase the Born cross section depending on the values of the renormalization and factorization scales, Comment: 46 pages, 13 figures

We compute the O(alpha_s^3) total cross section for the process (p pbar -> t tbar h) in the Standard Model, at \sqrt{s}=2 TeV. The next-to-leading order corrections drastically reduce the renormalization and factorization scale dependence of the Born cross section and slightly decrease the total cross section for renormalization and factorization scales between m_t and 2m_t., Comment: 5 pages, 5 figures, REVTeX, submitted to Phys. Rev. Lett

We discuss associated production of a Higgs boson with a pair of $t {\bar t}$ quarks at a future high energy $e^+e^-$ collider. The process $e^+e^-\to t {\bar t}h$ is particularly sensitive to the presence of new physics and we consider the MSSM and models with extra dimensions at the $TeV$ scale as examples., Comment: Talk given at the 5th International Collider Workshop (LCWS 2000), Fermilab, Batavia, Il, Oct 24-28, 2000

We review the prospects for studies of the top quark at the LHC., Comment: 111 pages, Latex, to appear in the Report of the ``1999 CERN Workshop on SM physics (and more) at the LHC'', M.Beneke, I.Efthymiopoulos, M.L.Mangano, J.Womersley (conveners)

We investigate the inclusive production of a Higgs boson with a pair of heavy quarks (t-tbar b-bbar), in e^+e^- collisions at high energies, sqrt(s)=500 GeV and sqrt(s)=1 TeV. We consider both the Standard Model and the supersymmetric case. In both cases O(alpha_s) QCD corrections are included. The associated production of a Higgs boson with a t-tbar pair is extremely sensitive to the top-Higgs Yukawa coupling and may allow the precision measurement of this coupling. In some regions of the supersymmetric parameter space the associated production of a Higgs boson with a b-bbar pair receives large resonant contributions and can have a significant rate., Comment: 6 pages, 6 figures, use sprocl.sty. Proceedings of the LCWS99, International Workshop on Linear Colliders, Sitges, Spain, May 1999

The transverse momentum flow inside jets is a sensitive measure of internal jet structure. For the current jets in deep inelastic scattering this jet shape measure is determined at order alpha_s^2, i.e. with up to three partons inside a single jet. The scale dependence of jet shapes in various jet algorithms is discussed. Results agree well with recent measurements by the ZEUS Collaboration, without introducing the hadronization parameter R_sep., Comment: 10 pages, LaTeX2.09, REVTeX3.1, 9 postscript figures

We investigate the inclusive production of the Higgs boson with a heavy quark pair, $t {\bar t}$ or $b {\bar b}$, in e^+e^- collisions at high energy. The ${\cal O}(\alpha_s)$ QCD corrections are included., Comment: Contribution to DPF99

We investigate the inclusive production of the Higgs bosons of the minimal supersymmetric model with a heavy quark pair, ($t {\bar t}$ and $b {\bar b}$), in e^+e^- collisions at high energies, $\sqrt{s}=500 GeV$ and $\sqrt{s}=1 TeV$. The ${\cal O}(\alpha_s)$ QCD radiative corrections are included and the dependence of the production rates on the parameters of the MSSM is explored. The associated production of a Higgs boson with a $b {\bar b}$ pair receives large resonant contributions and can have a significant rate.

We compute QCD corrections to the processes $e^+e^-\to t \bar t h^0$ and $pp\to t \bar t h^0$ by treating the Higgs boson as a parton which radiates off a heavy quark. This approximatiion is valid in the limits $M_h<

We review the latest calculations of the next-to-leading $\DSone$ effective Hamiltonian, relevant for $K\to \pi\pi$ transitions. Numerical results for the Wilson coefficients are given for different regularization schemes. Predictions of $\epse$, obtained using different approaches to evaluate the relevant hadronic matrix elements, are compared. Given the present value of the top mass, $m_t=(174\pm 17)$ GeV, all the analyses, in spite of the large theoretical uncertainties, indicate that the value of $\epse$ is smaller than $1\times 10^{-3}$., Comment: LaTeX, 29 pages, 5 postscript figures, contribution to the 2nd Daphne Physics Handbook

An upgraded analysis of $\ep$, $x_d$ and $\epp/\ep$, using the latest determinations of the relevant experimental and theoretical parameters, is presented. Using the recent determination of the top quark mass, $m_t=(174 \pm 17)$ GeV, our best estimate is $\epp/\ep= 3.1 \pm 2.5 $, which lies in the range given by E731. We describe our determination of $\epp/\ep$ and make a comparison with other similar studies. A detailed discussion of the matching of the full theory to the effective Hamiltonian, written in terms of lattice operators, is also given., Comment: LaTeX, 45 pages, 6 postscript figures

We present upgraded theoretical predictions for inclusive and exclusive radiative decays of {\it B} mesons. Our results include those next-to-leading order corrections that have already been computed. Our best estimates in the Standard Model are $BR(B \rightarrow K^* \gamma)=(4.3 \pm 0.9^{ +1.4}_{-1.0}) \times 10^{-5}$, $BR(B \rightarrow X_s \gamma) =(1.9 \pm 0.2\pm 0.5) \times 10^{-4}$, $\Gamma(B \rightarrow K^* \gamma)/ \Gamma(B \rightarrow X_s \gamma)=0.23 \pm 0.09$ and $BR(B \rightarrow X_s g)= (1.57 \pm 0.15 ^{+0.86}_{-0.59} \pm 0.23) \times 10^{-3}$. We also consider limits found with two-Higgs-doublet models., Comment: 17 pages (4 postscript file included), LaTeX, CERN-TH.7283/94, ROME prep. 94/1020, ULB-TH 09/94

We present the results for the Next-to-Leading Order effective hamiltonian for $\Delta S\!=\! 1$ decays, in presence of both QCD and QED corrections, and update the existing theoretical predictions for $\epsilon^\prime/\epsilon$. To appear on the Proceedings of the Third KEK Topical Conference on CP Violation, its Implications to Particle Physics and Cosmology, Tsukuba, 16-18 November 1993, Comment: 8 pages (macro and .sty files appended)

We discuss in detail the calculation of the leading order QCD corrections to the Effective Hamiltonian which governs $b \rightarrow s\, \gamma$ and $b \rightarrow s \, g$ transitions in three different regularization schemes (HV, NDR and DRED). We show that intermediate stages of the calculation do depend on the regularization, but the same scheme independent coefficients can be obtained in all the considered schemes. A detailed discussion of the results already present in the literature is also given., Comment: 35 pp + 4 figs not included (available by anonymous ftp at amisan.iss.infn.it (141.108.15.215), directory /ftp/dred ), LaTeX, ROME 973/93, INFN-ISS 93/6, ULB-TH 15/93

We present a calculation of the effective weak Hamiltonian which governs $b \rightarrow s\, \gamma$ and $b \rightarrow s \, g$ transitions in two different renormalization schemes (NDR and HV). In the leading logarithmic approximation, we show that the coefficients of the effective Hamiltonian are scheme independent only when one takes correctly into account the scheme dependence of one- and two- loop diagrams. We demonstrate that in NDR there are contributions which were missed in previous calculations. These contributions are necessary to obtain scheme independent coefficients in the final results., Comment: 16 pp + 5 figures not included (available by anonymous ftp at amisan.iss.infn.it (141.108.15.215), directory /ftp/bsgamma), LaTeX, LPTENS 93/28, ROME 93/958, ULB-TH 93/09

Using a left-right symmetric model with Spontaneous CP Violation and the hypothesis of a weakly first order electroweak phase transition we derive a relation between the produced baryon asymmetry and the observed parameter $\varepsilon$, describing CP violation in the $K$ system., Comment: 16 pages, Harvmac, 1 figure appended (use psbox.tex), ULB-TH 08/93

We present the results of our recent calculation of $\epsilon^{\prime}/ \epsilon$ at the Next-to-Leading (NLO) order in QCD and QED, in the framework of $\DSone$ Effective Hamiltonians. The operator matrix elements are taken from lattice QCD, at a scale $\mu=2\,\,\mbox{GeV}$. NLO corrections seem to lower the value of $\epsilon^{\prime}/\epsilon$, favouring the experimental result of E731. Contributions from different operators are analyzed and dependence on $\mt$, $\mu$ and $\Lambda_{\sss QCD}$ discussed. (Talk given at the XXVIIIth Rencontres de Moriond, ``Electro-Weak Interactions and Unified Theories'', March 13-19 1993)., Comment: 8 pages, LaTeX, figures available on request, ULB-TH 93/04

In this paper we present a calculation of the $\Delta S=1$ effective weak Hamiltonian including next-to-leading order QCD and QED corrections. At a scale $\mu$ of the order of few GeV, the Wilson coefficients of the operators are given in terms of the renormalization group evolution matrix and of the coefficients computed at a large scale $\sim M_W$. The expression of the evolution matrix is derived from the two-loop anomalous dimension matrix which governs the mixing of the relevant current-current and penguin operators, renormalized in some given regularization scheme. We have computed the anomalous dimension matrix up to and including order $\alphas^2$ and $\alphae \alphas$ in two different renormalization schemes, NDR and HV, with consistent results. We give many details on the calculation of the anomalous dimension matrix at two loops, on the determination of the Wilson coefficients at the scale $M_W$ and of their evolution from $M_W$ to $\mu$. We also discuss the dependence of the Wilson coefficients/operators on the regularization scheme., Comment: 59, LaTeX, ENS 93/11, ROME prep. 92/913, ULB-TH 93/03

We present a new calculation of the CP violation parameter $\epsilon^{\prime}/ \epsilon$. The results reported in this paper have been obtained by using the $\Delta S=1$ effective Hamiltonian computed at the next-to-leading order, including QCD and QED penguins. The matrix elements of the relevant operators have been taken from lattice QCD, at a scale $\mu=2$ GeV. At this relatively large scale, the perturbative matching between the relevant operators and the corresponding coefficients is quite reliable. The effect of the next-to-leading corrections is to lower the prediction obtained at the leading order, thus favouring the experimental result of E731. We analyze different contributions to the final result and compare the leading and next-to-leading cases., Comment: 19 pages, 6 figures included, LaTeX