Search

Large angular scale surveys in the absence of atmosphere are essential for measuring the primordial $B$-mode power spectrum of the Cosmic Microwave Background (CMB). Since this proposed measurement is about three to four orders of magnitude fainter than the temperature anisotropies of the CMB, in-flight calibration of the instruments and active suppression of systematic effects are crucial. We investigate the effect of changing the parameters of the scanning strategy on the in-flight calibration effectiveness, the suppression of the systematic effects themselves, and the ability to distinguish systematic effects by null-tests. Next-generation missions such as LiteBIRD, modulated by a Half-Wave Plate (HWP), will be able to observe polarisation using a single detector, eliminating the need to combine several detectors to measure polarisation, as done in many previous experiments and hence avoiding the consequent systematic effects. While the HWP is expected to suppress many systematic effects, some of them will remain. We use an analytical approach to comprehensively address the mitigation of these systematic effects and identify the characteristics of scanning strategies that are the most effective for implementing a variety of calibration strategies in the multi-dimensional space of common spacecraft scan parameters. We also present Falcons, a fast spacecraft scanning simulator that we developed to investigate this scanning parameter space.

LiteBIRD, the next-generation cosmic microwave background (CMB) experiment, aims for a launch in Japan's fiscal year 2032, marking a major advancement in the exploration of primordial cosmology and fundamental physics. Orbiting the Sun-Earth Lagrangian point L2, this JAXA-led strategic L-class mission will conduct a comprehensive mapping of the CMB polarization across the entire sky. During its 3-year mission, LiteBIRD will employ three telescopes within 15 unique frequency bands (ranging from 34 through 448 GHz), targeting a sensitivity of 2.2\,$\mu$K-arcmin and a resolution of 0.5$^\circ$ at 100\,GHz. Its primary goal is to measure the tensor-to-scalar ratio $r$ with an uncertainty $\delta r = 0.001$, including systematic errors and margin. If $r \geq 0.01$, LiteBIRD expects to achieve a $>5\sigma$ detection in the $\ell=$2-10 and $\ell=$11-200 ranges separately, providing crucial insight into the early Universe. We describe LiteBIRD's scientific objectives, the application of systems engineering to mission requirements, the anticipated scientific impact, and the operations and scanning strategies vital to minimizing systematic effects. We will also highlight LiteBIRD's synergies with concurrent CMB projects., Comment: 23 pages, 9 figures, 1 table, SPIE Astronomical Telescopes + Instrumentation 2024

We present detailed forecasts for the constraints on primordial magnetic fields (PMFs) that will be obtained with the LiteBIRD satellite. The constraints are driven by the effects of PMFs on the CMB anisotropies: the gravitational effects of magnetically-induced perturbations; the effects on the thermal and ionization history of the Universe; the Faraday rotation imprint on the CMB polarization; and the non-Gaussianities induced in polarization anisotropies. LiteBIRD represents a sensitive probe for PMFs and by exploiting all the physical effects, it will be able to improve the current limit coming from Planck. In particular, thanks to its accurate $B$-mode polarization measurement, LiteBIRD will improve the constraints on infrared configurations for the gravitational effect, giving $B_{\rm 1\,Mpc}^{n_{\rm B} =-2.9} < 0.8$ nG at 95% C.L., potentially opening the possibility to detect nanogauss fields with high significance. We also observe a significant improvement in the limits when marginalized over the spectral index, $B_{1\,{\rm Mpc}}^{\rm marg}< 2.2$ nG at 95% C.L. From the thermal history effect, which relies mainly on $E$-mode polarization data, we obtain a significant improvement for all PMF configurations, with the marginalized case, $\sqrt{\langle B^2\rangle}^{\rm marg}<0.50$ nG at 95% C.L. Faraday rotation constraints will take advantage of the wide frequency coverage of LiteBIRD and the high sensitivity in $B$ modes, improving the limits by orders of magnitude with respect to current results, $B_{1\,{\rm Mpc}}^{n_{\rm B} =-2.9} < 3.2$ nG at 95% C.L. Finally, non-Gaussianities of the $B$-mode polarization can probe PMFs at the level of 1 nG, again significantly improving the current bounds from Planck. Altogether our forecasts represent a broad collection of complementary probes, providing conservative limits on PMF characteristics that will be achieved with LiteBIRD., Comment: 51 pages, 24 figures, abstract shortened

We present a study of the impact of an uncertainty in the beam far side-lobe knowledge on the measurement of the Cosmic Microwave Background $B$-mode signal at large scale. It is expected to be one of the main source of systematic effects in future CMB observations. Because it is crucial for all-sky survey missions to take into account the interplays between beam systematic effects and all the data analysis steps, the primary goal of this paper is to provide the methodology to carry out the end-to-end study of their effect for a space-borne CMB polarization experiment, up to the cosmological results in the form of a bias $\delta r$ on the tensor-to-scalar ratio $r$. LiteBIRD is dedicated to target the measurement of CMB primordial $B$ modes by reaching a sensitivity of $\sigma \left( r \right) \leq 10^{-3}$ assuming $r=0$. As a demonstration of our framework, we derive the relationship between the knowledge of the beam far side-lobes and the tentatively allocated error budget under given assumptions on design, simulation and component separation method. We assume no mitigation of the far side-lobes effect at any stage of the analysis pipeline. We show that $\delta r$ is mostly due to the integrated fractional power difference between the estimated beams and the true beams in the far side-lobes region, with little dependence on the actual shape of the beams, for low enough $\delta r$. Under our set of assumptions, in particular considering the specific foreground cleaning method we used, we find that the integrated fractional power in the far side-lobes should be known at a level as tight as $\sim 10^{-4}$, to achieve the required limit on the bias $\delta r < 1.9 \times 10^{-5}$. The framework and tools developed for this study can be easily adapted to provide requirements under different design, data analysis frameworks and for other future space-borne experiments beyond LiteBIRD.

LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. The Japan Aerospace Exploration Agency (JAXA) selected LiteBIRD in May 2019 as a strategic large-class (L-class) mission, with an expected launch in the late 2020s using JAXA's H3 rocket. LiteBIRD is planned to orbit the Sun-Earth Lagrangian point L2, where it will map the cosmic microwave background (CMB) polarization over the entire sky for three years, with three telescopes in 15 frequency bands between 34 and 448 GHz, to achieve an unprecedented total sensitivity of 2.2$\mu$K-arcmin, with a typical angular resolution of 0.5$^\circ$ at 100 GHz. The primary scientific objective of LiteBIRD is to search for the signal from cosmic inflation, either making a discovery or ruling out well-motivated inflationary models. The measurements of LiteBIRD will also provide us with insight into the quantum nature of gravity and other new physics beyond the standard models of particle physics and cosmology. We provide an overview of the LiteBIRD project, including scientific objectives, mission and system requirements, operation concept, spacecraft and payload module design, expected scientific outcomes, potential design extensions and synergies with other projects., Comment: 155 pages, accepted for publication in PTEP

A methodology to provide the polarization angle requirements for different sets of detectors, at a given frequency of a CMB polarization experiment, is presented. The uncertainties in the polarization angle of each detector set are related to a given bias on the tensor-to-scalar ratio $r$ parameter. The approach is grounded in using a linear combination of the detector sets to obtain the CMB polarization signal. In addition, assuming that the uncertainties on the polarization angle are in the small angle limit (lower than a few degrees), it is possible to derive analytic expressions to establish the requirements. The methodology also accounts for possible correlations among detectors, that may originate from the optics, wafers, etc. The approach is applied to the LiteBIRD space mission. We show that, for the most restrictive case (i.e., full correlation of the polarization angle systematics among detector sets), the requirements on the polarization angle uncertainties are of around 1 arcmin at the most sensitive frequency bands (i.e., $\approx 150$ GHz) and of few tens of arcmin at the lowest (i.e., $\approx 40$ GHz) and highest (i.e., $\approx 400$ GHz) observational bands. Conversely, for the least restrictive case (i.e., no correlation of the polarization angle systematics among detector sets), the requirements are $\approx 5$ times less restrictive than for the previous scenario. At the global and the telescope levels, polarization angle knowledge of a few arcmins is sufficient for correlated global systematic errors and can be relaxed by a factor of two for fully uncorrelated errors in detector polarization angle. The reported uncertainty levels are needed in order to have the bias on $r$ due to systematics below the limit established by the LiteBIRD collaboration., Comment: 26 pages, 6 figures. Minor changes to match the final version in JCAP

We consider a 1+3 dimensional spin system. The spin-wave (magnon) field is described by the O(3) non-linear sigma model with a symmetry-breaking potential. This interacts with a slow spin SU(2) doublet Schrodinger fermion. The interaction is described by a generalized nonperturbative Yukawa coupling, and the self-consistency condition is solved with the aid of a non-relativistic Gribov equation. When the Yukawa coupling is sufficiently strong, the solution exhibits supercriticality and soft confinement, in a way that is quite analogous to Gribov's light-quark confinement theory. The solution corresponds to a new type of spin polaron, whose condensation may lead to exotic superconductivity., Comment: 8 pages, uses axodraw.sty; the final publication is available at link.springer.com

We discuss the consequences of spin current conservation in systems with SU(2) spin symmetry that is spontaneously broken by partial magnetic order, using a momentum-space approach. The long-distance interaction is mediated by Goldstone magnons, whose interaction is expressed in terms of the electron Green's functions. There is also a Higgs mode, whose excitation energy can be calculated. The case of fast magnons obeying linear dispersion relation in three spatial dimensions admits nonperturbative treatment using the Gribov equation, and the solution exhibits singular behaviour which has an interpretation as a tower of spin-1 electronic excitations. This occurs near the Mott insulator state. The electrons are more free in the case of slow magnons, where the perturbative corrections are less singular at the thresholds. We then turn our attention to the problem of high-Tc superconductivity, through the discussion of the stability of the antiferromagnetic ground state in two spatial dimensions. We argue that this is caused by an effective mixing of the Goldstone and Higgs modes, which in turn is caused by an effective Goldstone-boson condensation. The instability of the antiferromagnetic system is analyzed by studying the non-perturbative behaviour of the Higgs boson self-energy using the Dyson-Schwinger equations., Comment: 41 pages, 12 figures

We discuss the stability of the antiferromagnetic ground state in two spatial dimensions. We start with a general analysis, based on Gribov's current-conservation techniques, of the bosonic modes in systems with magnetic order. We argue that the Goldstone $\phi$ and Higgs $h$ modes mix in antiferromagnetic systems, and this leads to an effective $hh\phi$ three-point interaction. We then analyze the instability of the antiferromagnetic system in two spatial dimensions by studying the non-perturbative behaviour of the Higgs boson self-energy using the Dyson--Schwinger equations. The ground state turns out to be unstable for all values of the three-point coupling. We interpret this as being due to the formation of a (high-$T_C$) superconducting condensate. The carrier doping dependence of the energy gap has a general behaviour that is consistent with high-$T_C$ superconductivity. Superconductivity co-exists with antiferromagnetic order for large magnetization, or small doping., Comment: This paper has been withdrawn by the author due to the incomplete understanding of the physics involved. The formalism is worked out more fully in arXiv:1112.6036

This paper has been withdrawn by the author, due to obsolete reference [4], insufficient discussion in sec. 4, and major conceptual error in sec. 5., Comment: This paper has been withdrawn

We present a derivation of the Gribov equation for the gluon/photon Green's function D(q). Our derivation is based on the second derivative of the gauge-invariant quantity Tr ln D(q), which we interpret as the gauge-boson `self-loop'. By considering the higher-order corrections to this quantity, we are able to obtain a Gribov equation which sums the logarithmically enhanced corrections. By solving this equation, we obtain the non-perturbative running coupling in both QCD and QED. In the case of QCD, alpha_S has a singularity in the space-like region corresponding to super-criticality, which is argued to be resolved in Gribov's light-quark confinement scenario. For the QED coupling in the UV limit, we obtain a \propto Q^2 behaviour for space-like Q^2=-q^2. This implies the decoupling of the photon and an NJLVL-type effective theory in the UV limit., Comment: 12 pages, 5 figures; version to be published in Eur. Phys. J. C

We argue that the evolution of coloured partons into colour-singlet hadrons has approximate factorization into an extended parton-shower phase and a colour-singlet resonance--pole phase. The amplitude for the conversion of colour connected partons into hadrons necessarily resembles Regge-pole amplitudes since qq-bar resonance amplitudes and Regge-pole amplitudes are related by duality. A `Regge-cascade' factorization property of the N-point Veneziano amplitude provides further justification of this protocol. This latter factorization property, in turn, allows the construction of general multi-hadron amplitudes in amplitude-squared factorized form from (1->2) link amplitudes. We suggest an algorithm with cascade-decay configuration, ordered in the transverse momentum, suitable for Monte-Carlo simulation. We make a simple implementation of this procedure in Herwig++, obtaining some improvement to the description of the event-shape distributions at LEP., Comment: 10 pages, 9 figures

We consider the process $\gamma\gamma\to H_1\bar H_2$ where $H_1$ and $H_2$ are either mesons or baryons. The experimental findings for such quantities as the $p\bar p$ and $K_SK_S$ differential cross sections, in the energy range currently probed, are found often to be in disparity with the scaling behaviour expected from hard constituent scattering. We discuss the long-distance pole--resonance contribution in understanding the origin of these phenomena, as well as the amplitude relations governing the short-distance contribution which we model as a scaling contribution. When considering the latter, we argue that the difference found for the $K_SK_S$ and the $K^+K^-$ integrated cross sections can be attributed to the s-channel isovector component. This corresponds to the $\rho\omega\to a$ subprocess in the VMD (vector-meson-dominance) language. The ratio of the two cross sections is enhanced by the suppression of the $\phi$ component, and is hence constrained. We give similar constraints to a number of other hadron pair production channels. After writing down the scaling and pole--resonance contributions accordingly, the direct summation of the two contributions is found to reproduce some salient features of the $p\bar p$ and $K^+K^-$ data., Comment: 12 pages, 9 figures, revised version to be published in EPJC

A good fit to the CDF underlying event is obtained in the multiple parton scattering picture using HERWIG, after modifying the cluster hadronization algorithm as suggested by our previous study and adopting a larger maximum cluster size. The number of scatters per event is generated simply as a Poisson distribution. If our picture is correct, the baryon yield should be enhanced in the underlying event. This effect may be studied by measuring the proton-to-pion ratio., Comment: 23 pages, 8 figures

We first suppose that low-energy hadron pair photoproduction reactions gamma(*) gamma(*) -> h h-bar are dominated by s-channel resonance contributions. Their normalization is then calculated by their correspondence with the Reggeon term in the Regge parametrization of the gamma h total cross sections. For the case of p p-bar, we make use of the measured gamma p total cross section, and for the case of K+K-, we make use of the corresponding total cross section that is estimated using Regge factorization. For hadrons that have no such data, we can only provide rough estimation based on the additive quark rule. As an effective approach that is convenient and parameter-free, we adopt the Veneziano model in the simplest form. The model is only applicable to the region of low centre-of-mass energy. When the transverse momentum is large, perturbative QCD takes over, whereas in the Regge region, it is known that the Regge pole picture fails in photoproduction. Despite the shortcomings of the model, we find that the parameter-free amplitudes offer a sound description of the data at hand., Comment: 24 pages, 11 figures

If, as is commonly accepted, the colour-singlet, `preconfined', perturbative clusters are the primary units of hadronization, then the electric charge is necessarily compensated locally at the scale of the typical cluster mass. As a result, the minijet electric charge is suppressed at scales that are greater than the cluster mass. We hence argue, and demonstrate by means of Monte Carlo simulations using HERWIG, that the scale at which charge compensation is violated is close to the mass of the clusters involved in hadronization, and its measurement would provide a clue to resolving the nature of the dynamics. We repeat the calculation using PYTHIA and find that the numbers produced by the two generators are similar. The cluster mass distribution is sensitive to soft emission that is considered unresolved in the parton shower phase. We discuss how the description of the splitting of large clusters in terms of unresolved emission modifies the algorithm of HERWIG, and relate the findings to the yet unknown underlying nonperturbative mechanism. In particular, we propose a form of $\alpha_S$ that follows from a power-enhanced beta function, and discuss how this $\alpha_S$ that governs unresolved emission may be related to power corrections. Our findings are in agreement with experimental data., Comment: 37 pages, 20 figures

We consider the recent proposal that the distribution of the difference between azimuthal angles of the two accompanying jets in gluon-fusion induced Higgs-plus-two-jet events at LHC reflects the CP of the Higgs boson produced. We point out that the hierarchy between the Higgs boson mass and the jet transverse energy makes this observable vulnerable to logarithmically enhanced higher-order perturbative corrections. We present an evolution equation that describes the scale variation of the azimuthal angular correlation for the two jets. The emission of extra partons leads to a significant suppression of the correlation. Using the HERWIG Monte Carlo event generator, we carry out a parton-shower analysis to confirm the findings., Comment: Published version. 11 pages, 4 figures, uses JHEP3.cls

Many models that include small extra space dimensions predict graviton states which are well separated in mass, and which can be detected as resonances in collider experiments. It has been shown that the ATLAS detector at the Large Hadron Collider can identify such narrow states up to a mass of 2080 GeV in the decay mode G->ee, using a conservative model. This work extends the study of the ee channel over the full accessible parameter space, and shows that the reach could extend as high as 3.5 TeV. It then discusses ways in which the expected universal coupling of the resonance can be confirmed using other decay modes. In particular, the mode G-> di-photons is shown to be measurable with good precision, which would provide powerful confirmation of the graviton hypothesis. The decays G-> mu mu, WW, ZZ and jet--jet are measurable over a more limited range of couplings and masses. Using information from mass and cross-section measurements, the underlying parameters can be extracted. In one test model, the size of the extra dimension can be determined to a precision in length of 7x10^-33 m., Comment: 23 pages, 13 figures. The horizontal hatching in figures 6 and 8 is only displayed correctly if anti-aliasing is turned off

We examine the double Higgs production process at JLC. We focus our attention on the measurement of the Higgs self-coupling. The sensitivity of the triple Higgs coupling measurement is discussed in the Higgs mass range 100-200 GeV and the center of mass energy to be 500 GeV-1.5 TeV., Comment: Proceedings for the Linear Collider Workshop (LCWS2002) in Jeju Island, Korea, August 25-30, 2002, Talk given by Y. Yasui, 3 pages including 4 figures

A new release of the Monte Carlo program HERWIG (version 6.5) is now available. The main new features are: support for the Les Houches interface to matrix element generators; additional SM and MSSM Higgs processes in lepton collisions; additional matrix elements for the spin correlation algorithm; a new version of the ISAWIG interface; interface to the MC@NLO program for heavy quark, Higgs and vector boson production in hadron collisions. boson pair production in hadron collisions. This is planned to be the last major release of Fortran HERWIG. Future developments will be implemented in a new C++ event generator, HERWIG++., Comment: Updated to version 6.510, released Oct 31, 2005. Program available at http://hepwww.rl.ac.uk/theory/seymour/herwig/ or http://home.cern.ch/seymour/herwig/

We consider the production process e-e+ -> G\gamma of invisible gravitons (G) at future linear colliders. We discuss whether the angular distribution of the photon (\gamma) can be used to measure the spin of the invisible graviton, or of any other invisible objects produced. We propose a method based on the Fourier expansion of the transverse energy squared moment distribution of the photon. We provide justification for this method, and confirm, especially for the case of two extra dimensions, that the method is valid within a realistic setup, which includes the simulation of the Standard Model background, beamstrahlung, bremsstrahlung, calorimeter resolution and calorimeter coverage. When the number of extra dimensions is increased, the angular distribution does not provide sufficient information to extract the spin, but this method still offers a useful parameterization of the single photon cross section using which the nature of the missing object can be studied., Comment: Published version, one reference added, minor corrections and clarifications

We describe the implementation of supersymmetric processes in the HERWIG Monte Carlo event generator. We define relevant parameter and mixing conventions and list the hard scattering matrix elements. Our implementation is based on the Minimum Supersymmetric Standard Model, with the option of R-parity violation. The sparticle spectrum is completely general. Both hadron-hadron and lepton-lepton collisions are covered. This article supplements a separate publication in which the general features of HERWIG 6.2 are described, and updates the treatment of supersymmetry to version 6.4., Comment: 33 pages, uses JHEP3.cls; program available at http://hepwww.rl.ac.uk/theory/seymour/herwig/

A new release of the Monte Carlo program HERWIG (version 6.4) is now available. The main new features are: spin correlations between the production and decay of heavy fermions, i.e. top quarks, tau leptons and SUSY particles; polarization effects in SUSY production processes in lepton-lepton collisions; an interface to TAUOLA for tau decays; MSSM Higgs processes in lepton-lepton collisions., Comment: 3 pages, program available at http://hepwww.rl.ac.uk/theory/seymour/herwig/

A new release of the Monte Carlo program HERWIG (version 6.3) is now available. The main new features are new (MRST) built-in parton distribution functions, more SM gauge boson production processes, 2 to 3 MSSM Higgs production processes, an option to handle negative event weights, and an interface to the CIRCE beamstrahlung program., Comment: 10 pages, program available at http://hepwww.rl.ac.uk/theory/seymour/herwig/ Corrected PDF nomenclature

We assess the potential of future electron-positron linear colliders operating in the $e^\pm\gamma$ mode in detecting charged Higgs bosons with mass around and larger than the top quark mass, using Compton back-scattered photons from laser light. We compare the pair production mode, $e^-\gamma\to e^- H^+H^-$, to a variety of channels involving only one charged Higgs scalar in the final state, such as the tree-level processes $e^-\gamma\to \nu_e H^- \Phi^0 $ ($\Phi^0=h^0,H^0$ and $A^0$) and $e^-\gamma\to \nu_e f\bar f H^-$ ($f=b,\tau$ and $\nu_\tau$) as well as the loop-induced channel $e^-\gamma\to \nu_e H^-$. We show that, when the charged Higgs boson mass is smaller than or comparable to half the collider energy, $\sqrt s_{ee}\gsim 2M_{H^\pm}$, single production cross sections are of the same size as the pair production rate, whereas, for charged Higgs boson masses larger than $\sqrt s_{ee}/2$, all processes are heavily suppressed. In general, production cross sections of charged Higgs bosons via $e^\pm\gamma$ scatterings are smaller than those induced at an $e^+e^-$ collider and the latter represents a better option to produce and analyse such particles., Comment: 18 pages, latex, 9 figures

We study the single production of charged Higgs bosons in e+e- collisions, chiefly in the Minimal Supersymmetric Standard Model. Our analysis complements foregoing studies of the pair production channel especially in regions where the kinematic constraint suppresses pair production. We present cross sections relevant to experiments at the next generation linear colliders and some brief discussions of their phenomenology. Our analysis shows that the single production is a useful alternative channel for studying the phenomenology of charged Higgs bosons, and there are regions of parameter space where it is accessible beyond the kinematic limit for pair production., Comment: 21 pages including 9 figures

HERWIG is a general-purpose Monte Carlo event generator, which includes the simulation of hard lepton-lepton, lepton-hadron and hadron-hadron scattering and soft hadron-hadron collisions in one package. It uses the parton-shower approach for initial- and final-state QCD radiation, including colour coherence effects and azimuthal correlations both within and between jets. This article updates the description of HERWIG published in 1992, emphasising the new features incorporated since then. These include, in particular, the matching of first-order matrix elements with parton showers, a more correct treatment of heavy quark decays, and a wide range of new processes, including many predicted by the Minimal Supersymmetric Standard Model, with the option of R-parity violation. At the same time we offer a brief review of the physics underlying HERWIG together with details of the input and control parameters and the output data, to provide a self-contained guide for prospective users of the program. This version of the manual (version 3) is updated to HERWIG version 6.5, which is expected to be the last major release of Fortran HERWIG. Future developments will be implemented in a new C++ event generator, HERWIG++., Comment: 112 pages, updated to version 6.5; program available at http://hepwww.rl.ac.uk/theory/seymour/herwig/ and http://home.cern.ch/seymour/herwig/

A spectrum of massive graviton states is present in several recent theoretical models that include extra space dimensions. In some such models the graviton states are well separated in mass, and can be detected as resonances in collider experiments. The ability of the ATLAS detector at the Large Hadron Collider to identify such states and measure their properties is considered, in the case that the resonances are narrow compared to the experimental resolution. The discovery limits for the detection of the decay mode G->e+e- are derived. The angular distribution of the lepton pair is used to determine the spin of the intermediate state. In one specific model, the resonance can be detected up to a graviton resonance mass of 2080 GeV, while the angular distribution favours a spin-2 hypothesis over a spin-1 hypothesis at 90% confidence for resonance masses up to 1720 GeV., Comment: 12 pages, 5 figures. v2 has corrected cross-sections leading to favourable quantitative changes to results

The results obtained by the Working Group on Supersymmetry at the 1999 Les Houches Workshop on Collider Physics are summarized. Separate chapters treat "general" supersymmetry, R-parity violation, gauge mediated supersymmetry breaking, and anomaly mediated supersymmetry breaking., Comment: LaTeX, 110 pages with numerous .ps and .eps files. proc.tex is main tex file

The Les Houches Workshop on Physics at TeV Colliders took place from June 8-18, 1999. One of the three working groups at Les Houches concentrated on QCD issues, both at the Tevatron Collider and at the LHC. Besides the interest in QCD in its own right, QCD dynamics plays an important role in the production mechanisms for any new physics process that might be observed at either collider, as well as any processes that may form backgrounds to the new physics. This writeup serves both as a pedagogical overview of QCD as well as an update on the current status of the field., Comment: 179 pages, 65 figures

Report of the Higgs working group for the Workshop "Physics at TeV Colliders", Les Houches, France 8-18 June 1999. It contains 6 separate sections: 1. Measuring Higgs boson couplings at the LHC. 2. Higgs boson production at hadron colliders at NLO. 3. Signatures of Heavy Charged Higgs Bosons at the LHC. 4. Light stop effects and Higgs boson searches at the LHC. 5. Double Higgs production at TeV Colliders in the MSSM. 6. Programs and Tools for Higgs Bosons., Comment: Latex, 100 pages, style files included, also available at http://www.lpm.univ-montp2.fr:7082/~djouadi/houches/houches99.html

A new version of the Monte Carlo program HERWIG (version 6.1) is now available. This note gives brief details of the new features relative to the previous version (5.9). A fully updated manual will follow shortly. The main new features are: supersymmetric processes (both R-parity conserving and R-parity violating) in hadron-hadron collisions; the new process e+e- to 4 jets; matrix element corrections to top decay and Drell-Yan processes; new soft underlying event options; updates to particle data tables; new LaTeX and html printout options., Comment: 11 pages, latex figures, program and further details available at http://hepwww.rl.ac.uk/theory/seymour/herwig/

It has recently been shown that through the $\tau\nu$ decay mode the heavy charged Higgs bosons $H^\pm$ can be discovered at LHC over a vast region of the parameter space previously thought unaccessible. If the charged Higgs bosons are discovered in this decay mode and the measurements of its mass and $\tan\beta$ are made, it allows us to make greater use of the dominant but QCD background contaminated $bt$ decay mode by cuts suppressing phase space for the background. In this paper we study the top quark polarisation in the $bt$ decay mode. When $\tan\beta$ is either moderately large ($\tan\beta\gtrsim9$) or small ($\tan\beta\lesssim4), the correlation effects can be used as a signal of $H^\pm$ production. We outline the analysis procedure for various decay signatures. As an example, we demonstrate the application of our procedure to the dominant production process $gb\to tH^-$ at LHC. The effect is clearly observable for $H^\pm$ mass between 200 GeV and 500 GeV in both leptonic and hadronic channels, but at 500 GeV the boost on the top quark starts to prevent the reconstruction of invariant masses, and hence the observation of the correlation effect, in the hadronic decay channel., Comment: 17 pages including 8 figures

We discuss the search for the heavy charged Higgs bosons H^\pm, implicitly of the Minimal Supersymmetric Standard Model, in the tau-nu decay mode at the LHC. Compared to the dominant decay mode H^\pm\to bt, the channel suffers from suppression due to the branching ratio and the lack of direct mass reconstruction, but the reduced QCD background makes it a feasible channel especially in the large tan(beta) region. We study the production in `bt fusion' via bg\to tH^-, and the leading irreducible background bg\to tW^-. Our results indicate that for the H^\pm mass of greater than 200 GeV and up to 1 TeV and higher, they can be discovered in this channel for a vast range of the parameter space, down to at least tan(beta)\sim3 and potentially the whole range of tan(beta) down to 1.5 if the signal selection efficiency can be improved fourfold. Our analysis is sensitive to top quark identification at large rapidity, and should be supplemented with a full study including jet showering and detector effects., Comment: 23 pages, 6 figures

Barrientos Bendezu' and Kniehl [hep-ph/9807480] recently suggested that $W^\pm H^\mp$ associated production may be a useful channel in the search for the elusive heavy charged Higgs bosons of the 2 Higgs Doublet Model at the Large Hadron Collider. We investigate the phenomenology of this mechanism in the Minimal Supersymmetric Standard Model, with special attention paid to the most likely heavy Higgs decay, $H^\mp\to tb\to b\bar b W^\mp$, and to the irreducible background from top pair production. We find that the semi-leptonic signature `$b\bar b W^+W^-\to b\bar b jj \ell$ + missing momentum' is dominated by top-antitop events, which overwhelm the charged Higgs signal over the heavy mass range that can be probed at the CERN collider, Comment: 17 pages, latex, epsfig, 8 figures (paper also available at http://www.hep.phy.cam.ac.uk/theory/papers/ )

The colour connection structure of QCD ($2\to2$) processes is discussed, with emphasis on its application to the supersymmetric 2 parton $\to$ 2 sparton processes, which are currently being implemented in the HERWIG Monte Carlo event generator. The procedure described by Marchesini and Webber is found to be inadequate, and a new method is proposed. However, this alteration is unlikely to significantly affect the theoretical predictions for soft gluon radiation. A complete list of supersymmetric QCD $2\to2$ matrix elements and their colour decompositions is presented., Comment: 12 pages, 4 figures, LaTeX2e

We study charged Higgs boson production at future electron-proton colliders in the framework of the Minimal Supersymmetric Standard Model. We focus our attention to the case of single-top production and decay through the channel $t\to bH^\pm$ and of vector-scalar fusion via $W^{\pm*} \Phi^*\to H^\pm$ (where $\Phi=H,h$ and $A$). We consider the signature $H^\pm\to \tau\nu_\tau$ and compare it to the irreducible background from Standard Model interactions. For $M_{H^\pm}

The production of top quarks in single mode at future ep colliders is studied, the attention being mainly focused to the case of the proposed LEPXLHC collider. We are motivated to reanalyse such a process following the discovery of the top quark at Fermilab. Thanks to the measurement of its mass one is now able to establish more accurately the relevance of single top production for itself and for many other processes to which it may act as a background. In addition, the recent improvement of our knowledge of the quark and gluon dynamics inside the proton now allows one to pin down the dependence of single top production on the partonic structure functions. Both the leptonic and hadronic decay channels of the top quark are studied and compared to the yield of the corresponding irreducible background in presence of b-tagging, Comment: 28 pages, latex, epsfig, 10 postscript figures, complete paper available at ftp://axpa.hep.phy.cam.ac.uk/moretti/cavendish_9704 and at http://www.hep.phy.cam.ac.uk/theory/papers/

The complete matrix elements for $e^+e^-\to b\bar bW^\pm H^\mp$ and $e^+e^-\to b\bar bH^+H^-$ are computed at tree-level within the Minimal Supersymmetric Standard Model. Rates of interest to phenomenological analyses at the Next Linear Collider are given. In particular, we analyse: (i) $t\bar t$ pair production followed by the top decays into $b\bar bW^\pm H^\mp$ and $b\bar b H^+H^-$ final states; (ii) $H^+H^-$ signals in which $H^\pm\to h W^\pm \to b\bar b W^\pm$ and $H^\pm\to tb\to b\bar b W^\pm$. Top and Higgs finite width effects are included as well as all those due to the irreducible backgrounds., Comment: 34 pages, latex, epsfig, 15 postscript figures bitmapped at 1000dpi, complete paper including high resolution plots available at ftp://axpa.hep.phy.cam.ac.uk/moretti/cavendish_9701 and at http://www.hep.phy.cam.ac.uk/theory/papers/

In this paper we compare $H^+H^-$ and $W^+W^-$ into four-fermion production at centre-of-mass energies typical of LEP2 and somewhat larger. The theoretical framework considered is the Minimal Supersymmetric Standard Model. The interest in exploiting the $e^+e^-$ CERN collider at values of $\sqrt s$ greater than 192 GeV could come from the discovery of Supersymmetric signals during runs at lower energy. If these indicate that a charged Higgs boson exists in the mass range $\MH\approx95-105$ GeV, then a few years of running at $\sqrt s=205-215$ GeV and nominal luminosity could make the detection of such scalars feasible, in the purely leptonic channel $\tau\nu_\tau\tau\nu_\tau$ and, for small $\tb$'s, also in the semi-hadronic(leptonic) one ${jj}\tau\nu_\tau$. Charged Higgs bosons of the above nature cannot be produced by the beam energies approved at present for LEP2. However, if runs beyond the so-called `192 GeV cryogenic limit' will be approved by the CERN Council, our selection procedure will enable us to establish the presence, or otherwise, of charged Higgs bosons in the mentioned mass range, Comment: 30 pages, latex, epsfig, 12 postscript figures, complete paper available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9615 and at http://www.hep.phy.cam.ac.uk/theory/papers/

We study integrated and differential rates for the production of charged Higgs bosons $H^\pm$ of the Minimal Supersymmetric Standard Model via b-quark initiated subprocesses in pp collisions at the Large Hadron Collider. In detail, we compute cross sections and distributions of the reactions: $bU \to bDH^+ \to bD\tau^+\nu_\tau\oplus C.C.$ and $bU \to bDH^+ \to bD t\bar b \to bDb\bar b {jj}\oplus C.C.$, for a $H^\pm$ scalar in the intermediate (i.e., $M^\pmm_t+m_b$) mass range, respectively (U and D represent generic u- and d-type light quarks). In the first case, a detailed treatment of various possible backgrounds is also given., Comment: 25 pages, latex, epsfig, 12 postscript figures bitmapped at 150dpi, complete paper including high resolution plots available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9613 and at http://www.hep.phy.cam.ac.uk/theory/papers/

Heavy flavour tagging provides a broad range of possibilities in testing QCD features at LEP. We present here a study of 4jets events at LEP I where the so-called light gluinos could be directly produced. We show that microvertex techniques offer a unique chance to exploit simple kinematical distributions in order to optimise the signal coming from gluino production with respect to the background of ordinary QCD events. Our results indicate that experimental analyses along the lines suggested here can exclude or reveal the presence of a gluino for masses up to 10 GeV and lifetimes below 10$^{-9}$ sec. We also point out that a large fraction of gluino events could decay in configurations carrying large missing energy, so to escape the usual selection criteria of 4jet samples. In our study, mass effects of quarks and gluinos have been taken into account exactly. Our results are independent from both the jet algorithm and its resolution parameter.}, Comment: 28 pages, 9 figures embedded with epsfig, Latex. Major revision taking into account latest bounds. Version to appear in Zeit. f. Phys. C

We briefly report about a possible settlement of the still ongoing dispute concerning the existence of SUSY signals in 4jet events at LEP1. We base our arguments on a simple selection strategy exploiting secondary vertex tagging and kinematical constraints, which could allow one to access or exclude gluino events for a broad range of masses and lifetimes., Comment: 10 pages, LaTeX, 3 PostScript figures embedded with epsfig. Complete ps paper and figures available also at ftp://ftae3.ugr.es/pub/rmt/ugrft70.ps