L. Pape

We derive non-flat cosmological models for two cases (i.e., dust and radiation) in the context of Møller’s tetradic theory (MTT) of gravitation using the tetrad that creates the non-flat Friedmann–Robertson–Walker (FRW) metric. These two models are affected by the free dimensional parameter, λ, that characterized MTT, which approaches zero in the flat case for both models. Using standard definitions of thermodynamics, we calculate the radius horizon, Hawking temperature, and entropy of our non-flat models in the framework of cosmology and show the effect of λ on open and closed universes. We then use the first law of thermodynamics to construct non-flat cosmological models via the non-extensive thermodynamic approach. The resulting models are affected by λ and the extensive parameter, δ, which quantifies the effect of non-extensive thermodynamics. When we set, λ=0 and δ=1, we return to Einstein’s general relativity models. We study the evolution of our models in the presence of collisionless non-relativistic matter and describe precise forms of the dark energy density and equation-of-state parameter constraining the non-extensive thermodynamic parameter. We show that insertion of the non-extensive thermodynamic parameter affects the non-flat FRW universe in a manner that noticeably differs from that observed under normal thermodynamics. We also show that the deceleration of the open universe behaves as dark energy in a future epoch, i.e., when the redshift approaches −1, i.e., z≈−1.

This biennial Review summarizes much of particle physics. Using data from previous editions, plus 2658 new measurements from 644 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. Among the 112 reviews are many that are new or heavily revised including those on Heavy-Quark and Soft-Collinear Effective Theory, Neutrino Cross Section Measurements, Monte Carlo Event Generators, Lattice QCD, Heavy Quarkonium Spectroscopy, Top Quark, Dark Matter, Vcb & Vub, Quantum Chromodynamics, High-Energy Collider Parameters, Astrophysical Constants, Cosmological Parameters, and Dark Matter. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov/. The 2012 edition of Review of Particle Physics is published for the Particle Data Group as article 010001 in volume 86 of Physical Review D. This edition should be cited as: J. Beringer et al. (Particle Data Group), Phys. Rev. D 86, 010001 (2012).Received 18 July 2012DOI:https://doi.org/10.1103/PhysRevD.86.010001© 2012 Regents of the University of California*The publication of the Review of Particle Physics is supported by the Director, Office of Science, Office of High Energy and Nuclear Physics, the Division of High Energy Physics of the U.S. Department of Energy under Contract No. DE–AC02–05CH11231; by the U.S. National Science Foundation under Agreement No. PHY-0652989; by the European Laboratory for Particle Physics (CERN); by an implementing arrangement between the governments of Japan (MEXT: Ministry of Education, Culture, Sports, Science and Technology) and the United States (DOE) on cooperative research and development; and by the Italian National Institute of Nuclear Physics (INFN).

This biennial Review summarizes much of Particle Physics. Using data from previous editions, plus 2205 new measurements from 667 papers, we list, evaluate, and average measured properties of gauge bosons, leptons, quarks, mesons, and baryons. We also summarize searches for hypothetical particles such as Higgs bosons, heavy neutrinos, and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables, figures, formulae, and reviews of topics such as the Standard Model, particle detectors, probability, and statistics. This edition features expanded coverage of CP violation in B mesons and of neutrino oscillations. For the first time we cover searches for evidence of extra dimensions (both in the particle listings and in a new review). Another new review is on Grand Unified Theories. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables, listings, and reviews (and errata) are also available on the Particle Data Group website: http://pdg.lbl.gov.

DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive limits on production cross-sections and particle masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles.

We present results for the differential cross sections of neutrinos and antineutrinos on nucleons in the energy range E = 2−200 GeV, from the BEBC and Gargamelle experiments. The structure functions F2, 2χF1 and χF3 have been evaluated as a function of χ and q2. Deviations are observed from Bjorken scaling, which are very similar to those found in electron and muon inelastic scattering. For the Callan-Gross ratio, we find 2χF1F2 = 0.80 ± 0.12 and the corresponding value for 〈R〉 = 〈σSσT〉 = 0.15 ± 0.10. Our results are consistent with the Gross-Llewellyn-Smith sum rule; we measure ⩾2.5 ± 0.5 valence quarks per nucleon. Quark and antiquark distributions are given. The Nachtmann moments of F2 and χF3 are quantitatively consistent with the predictions from QCD. The value of the strong interaction parameter is λ = 0.74 ± 0.05 GeV without corrections, and 0.66 ± 0.05 GeV including αS2 corrections. The moments of the gluon distribution are found to be positive and indicate an χ distribution of gluons which is comparable with that of the valence quarks.

We update a previously-proposed set of supersymmetric benchmark scenarios, taking into account the precise constraints on the cold dark matter density obtained by combining WMAP and other cosmological data, as well as the LEP and $b \rightarrow s \gamma$ constraints. We assume that R parity is conserved and work within the constrained MSSM (CMSSM) with universal soft supersymmetry-breaking scalar and gaugino masses m 0 and m 1/2. In most cases, the relic density calculated for the previous benchmarks may be brought within the WMAP range by reducing slightly m 0, but in two cases more substantial changes in m 0 and m 1/2 are made. Since the WMAP constraint reduces the effective dimensionality of the CMSSM parameter space, one may study phenomenology along "WMAP lines" in the (m 1/2, m 0) plane that have acceptable amounts of dark matter. We discuss the production, decays and detectability of sparticles along these lines, at the LHC and at linear e + e - colliders in the sub- and multi-TeV ranges, stressing the complementarity of hadron and lepton colliders, and with particular emphasis on the neutralino sector. Finally, we preview the accuracy with which one might be able to predict the density of supersymmetric cold dark matter using collider measurements.

We propose a new set of supersymmetric benchmark scenarios, taking into account the constraints from LEP, b to s gamma, g_mu - 2 and cosmology. We work in the context of the constrained MSSM (CMSSM) with universal soft supersymetry-breaking masses and assume that R parity is conserved. We propose benchmark points that exemplify the different generic possibilities, including focus-point models, points where coannihilation effects on the relic density are important, and points with rapid relic annihilation via direct-channel Higgs poles. We discuss the principal decays and signatures of the different classes of benchmark scenarios, and make initial estimates of the physics reaches of different accelerators, including the Tevatron collider, the LHC, and e+ e- colliders in the sub- and multi-TeV ranges. We stress the complementarity of hadron and lepton colliders, with the latter favoured for non-strongly-interacting particles and precision measurements. We mention features that could usefully be included in future versions of supersymmetric event generators.

In 70 000 photos taken in BEBC during an experiment in which the 400 GeV proton beam of the CERN SPS was dumped into a massive Cu target 820 m upstream of BEBC, 70 interactions induced by neutral primaries above 10 GeV were observed. In 11 events the secondary charged lepton is an e−, in four events an e+. This number of electron events cannot be due to electron neutrinos from conventional sources (K, Λ, Σ− decays). The flux of the additional (prompt) neutrinos is evaluated. Possible origins are discussed in terms of charmed particles, τ's, and as yet undiscovered particles. Limits are given on axion production.

We interpret within the phenomenological MSSM (pMSSM) the results of SUSY searches published by the CMS collaboration based on the first ~1 fb^-1 of data taken during the 2011 LHC run at 7 TeV. The pMSSM is a 19-dimensional parametrization of the MSSM that captures most of its phenomenological features. It encompasses, and goes beyond, a broad range of more constrained SUSY models. Performing a global Bayesian analysis, we obtain posterior probability densities of parameters, masses and derived observables. In contrast to constraints derived for particular SUSY breaking schemes, such as the CMSSM, our results provide more generic conclusions on how the current data constrain the MSSM.

This biennial Review summarizes much of Particle Physics. Using data from previous editions plus new measurements from papers we list evaluate and average measured properties of gauge bosons leptons quarks mesons and baryons. We also summarize searches for hypothetical particles such as Higgs bosons heavy neutrinos and supersymmetric particles. All the particle properties and search limits are listed in Summary Tables. We also give numerous tables gures formulae and reviews of topics such as the Standard Model particle detectors probability and statistics. Among the reviews are many that are new or heavily revised including those on neutrino mixing CP violation in K D and B mesons Vcb the new exotic  particle extra dimensions grand unified theories cosmic background radiation dark matter cosmological parameters and big bang cosmology. A booklet is available containing the Summary Tables and abbreviated versions of some of the other sections of this full Review. All tables listings and reviews and errata are also available on the Particle Data Group website https://pdg.lbl.gov.

We motivate, propose and examine a new set of benchmark supersymmetric scenarios, some of which have non-universal Higgs scalar masses (NUHM) and others have gravitino dark matter (GDM). The scalar masses in these proposed models are either considerably larger or smaller than the narrow range allowed for the same gaugino mass m1/2 in the constrained MSSM (CMSSM) with universal scalar masses m0 and neutralino dark matter. Unlike the CMSSM, the proposed NUHM and GDM models with larger m0 may have large branching ratios for Higgs and/or Z production in the cascade decays of heavier sparticles, whose detection we discuss. The novel phenomenology of the GDM models depends on the nature of the next-to-lightest supersymmetric particle (NLSP), which has a lifetime exceeding 104 s in the proposed benchmark scenarios. In one GDM scenario the NLSP is the lightest neutralino χ, and the supersymmetric collider signatures are similar to those in previous CMSSM benchmarks, but with a distinctive spectrum that would be challenging for the LHC and ILC. In the other GDM scenarios based on minimal supergravity (mSUGRA), the NLSP is the lighter stau slepton $\tilde\tau_1$ , with a lifetime between ∼104 and 3×106 s. Every supersymmetric cascade would end in a $\tilde\tau_1$ , which would have a distinctive time-of-flight signature. Slow-moving $\tilde\tau_1$ ’s might be trapped in a collider detector or outside it, and the preferred detection strategy would depend on the $\tilde\tau_1$ lifetime. We discuss the extent to which these mSUGRA GDM scenarios could be distinguished from gauge-mediated models.

The elastic scattering of K+ mesons on protons is studied at 3.5 and 5 GeV/c. The total elastic cross-sections are found to be (4.36±0.36) mb and (3.82±0.41) mb respectively. The differential elastic cross-sections, which exhibit characteristic diffraction peaks, are fitted by dσ/dt=(dσ/dt)0 e αt , giving α=(3.85±0.12) and (4.70±0.21) (GeV/c)−2 for the two momenta respectively, with |t|⪝0.65 (GeV/c)2. The results are compared to those at neighbouring energies, giving some support to the presence of a real part of the forward scattering amplitude. The diffraction peak shows definite shrinking with increasing momenta. The data are examined in the light of models for high-energy scattering.

Multiplicity distributions of charged hadrons produced in νp interactions are studied using a sample of 7850 charged current interactions in BEBC. Multiplicity moments are studied as functions of the invariant mass of the hadronic system, W, and a comparison is made with other lepton- and hadron-induced reactions. The mean charged multiplicity 〈nch〉 is found to increase linearly with ln W2. The other multiplicity moments indicate a close similarity between the neutrino scattering and the class of annihilation processes. A study of the multiplicity distributions in the forward and backward directions in the hadronic c.m.s. gives results in qualitative agreement with the quark parton model.

In a second beam-dump experiment using BEBC the prompt neutrino flux has been measured and its characteristics studied. The use of targets of variable effective density allowed a determination of the conventional decay neutrino flux and a direct demonstration of a prompt neutrino signal. Assuming that the prompt neutrinos originate in the decay of charmed D mesons then a production cross section is estimated. An upper limit of 10% can be set to the proportion of interactions induced by τ neutrinos.

This chapter of the "Flavor in the era of LHC" workshop report discusses flavor-related issues in the production and decays of heavy states at the LHC at high momentum transfer Q, both from the experimental and the theoretical perspective. We review top quark physics, and discuss the flavor aspects of several extensions of the standard model, such as supersymmetry, little Higgs models or models with extra dimensions. This includes discovery aspects, as well as the measurement of several properties of these heavy states. We also present publicly available computational tools related to this topic.

The charged-current cross sections for neutrinos and antineutrinos on nucleons in the energy range 20–200 GeV are given. Taken in conjunction with the previous Gargamelle results, they show that σE is almost constant with energy for antineutrinos, and falls with energy for neutrinos. The value of 〈q2〉E decreases with energy for both neutrinos and antineutrinos, and these deviations from exact Bjorken scaling are consistent with those observed in electron and muon inelastic scattering. We find no evidence for new heavy quark states with right-handed coupling.

A new value of the upper limit for the branching ratio of the decay of K0S into e+e− has been experimentally obtained using a lead glass detector. The value is BR (K0S → e+e−) < 1.1 × 10−4 (90% CL).

We consider a class of on-shell constrained mass variables that are 3+1 dimensional generalizations of the Cambridge M T2 variable and that automatically incorporate various assumptions about the underlying event topology. The presence of additional on-shell constraints causes their kinematic distributions to exhibit sharper endpoints than the usual M T2 distribution. We study the mathematical properties of these new variables, e.g., the uniqueness of the solution selected by the minimization over the invisible particle 4-momenta. We then use this solution to reconstruct the masses of various particles along the decay chain. We propose several tests for validating the assumed event topology in missing energy events from new physics. The tests are able to determine: 1) whether the decays in the event are two-body or three-body, 2) if the decay is two-body, whether the intermediate resonances in the two decay chains are the same, and 3) the exact sequence in which the visible particles are emitted from each decay chain.

We critically reexamine the standard applications of the method of kinematical endpoints for sparticle mass determination. We consider the typical decay chain in supersymmetry (SUSY) → 02 → → 01, which yields a jet j, and two leptons ℓn± and ℓf∓. The conventional approaches use the upper kinematical endpoints of the individual distributions mjℓℓ, mjℓ(lo) = min {mjℓn,mjℓf} and mjℓ(hi) = max {mjℓn,mjℓf}, all three of which suffer from parameter space region ambiguities and may lead to multiple solutions for the SUSY mass spectrum. In contrast, we do not use mjℓℓ, mjℓ(lo) and mjℓ(hi), and instead propose a new set of (infinitely many) variables whose upper kinematic endpoints exhibit reduced sensitivity to the parameter space region. We then outline an alternative, much simplified procedure for obtaining the SUSY mass spectrum. In particular, we show that the four endpoints observed in the three distributions m2ℓℓ, m2jℓn∪m2jℓf and m2jℓn+m2jℓf are sufficient to completely pin down the squark mass m and the two neutralino masses m02 and m01, leaving only a discrete 2-fold ambiguity for the slepton mass m. This remaining ambiguity can be easily resolved in a number of different ways: for example, by a single additional measurement of the kinematic endpoint of any one out of the many remaining 1-dimensional distributions at our disposal, or by exploring the correlations in the 2-dimensional distribution of m2jℓn∪m2jℓf versus m2ℓℓ. We illustrate our method with two examples: the LM1 and LM6 CMS study points. An additional advantage of our method is the expected improvement in the accuracy of the SUSY mass determination, due to the multitude and variety of available measurements.

The general features of hadrons produced in charged current interaction of high-energy neutrinos on nucleons are shown to be basically consistent with the idea of quark fragmentation within the framework of the quark parton model. However, many of the effects observed are shown also to follow from longitudinal phase space. Evidence is presented for a rise in 〈pT2〉 with Q2 in qualitative agreement with the predictions of quantum chromodynamics (QCD).

An analysis is presented of the z distributions of secondary hadrons produced in 5600 charged current events from a BEBC neutrino-hydrogen experiment. Evidence is presented for scaling deviations in the z distributions and a breakdown of factorization in the single particle inclusive cross sections. The results are consistent with the leading order QCD predictions on the q2 dependence of nonsinglet moments of quark fragmentation functions, yielding a value of Λ ≈ 0.6 GeV.

The reaction νp→μ−pπ+ (777 events) is studied at neutrino energies from 5 to 200 GeV. A total of 551 events fit the channel νp→μ−Δ++ (1232) with χ2 probability greater than 2%. Decay angular distributions of the Δ++ are investigated and the density matrix elements are studied as functions of Q2, the square four-momentum transfer. The total Δ++ production cross section and the differential cross section dσ/dQ2 are determined. Using the Schreiner-von Hippel parametrization of the Adler model, the value of the axial mass determined by fitting the total cross sections above 20 GeV is MA = 0.85±0.10 GeV. The model describes the differential cross sections reasonably well above Q2⋍0.2 GeV2. Disagreements, however, are found for some values of the density matrix elements of the Δ++ decay angular distributions and their Q2 dependence. The (pπ+) mass region above the Δ++(1232) contains evidence for the presence of higher mass Δ++ resonances and, above 2 GeV, for the forward emission of fast π+.

This report summarizes a study of the physics potential of the CLIC e+e- linear collider operating at centre-of-mass energies from 1 TeV to 5 TeV with luminosity of the order of 10^35 cm^-2 s^-1. First, the CLIC collider complex is surveyed, with emphasis on aspects related to its physics capabilities, particularly the luminosity and energy, and also possible polarization, \gamma\gamma and e-e- collisions. The next CLIC Test facility, CTF3, and its R&D programme are also reviewed. We then discuss aspects of experimentation at CLIC, including backgrounds and experimental conditions, and present a conceptual detector design used in the physics analyses, most of which use the nominal CLIC centre-of-mass energy of 3 TeV. CLIC contributions to Higgs physics could include completing the profile of a light Higgs boson by measuring rare decays and reconstructing the Higgs potential, or discovering one or more heavy Higgs bosons, or probing CP violation in the Higgs sector. Turning to physics beyond the Standard Model, CLIC might be able to complete the supersymmetric spectrum and make more precise measurements of sparticles detected previously at the LHC or a lower-energy linear e+e- collider: \gamma\gamma collisions and polarization would be particularly useful for these tasks. CLIC would also have unique capabilities for probing other possible extensions of the Standard Model, such as theories with extra dimensions or new vector resonances, new contact interactions and models with strong WW scattering at high energies. In all the scenarios we have studied, CLIC would provide significant fundamental physics information beyond that available from the LHC and a lower-energy linear e+e- collider, as a result of its unique combination of high energy and experimental precision.

In film taken with BEBC filled with a Ne(74%mol)/H2 mixture and exposed to the CERN narrow-band neutrino beam (200 GeV), tenμ−μ+, one μ−μ+μ−and five μ−e+ events were found in the ν exposure and two μ+μ− events and one μ+e− event in the ν exposure. Assuming the same production mechanism for μμ and μe events, the relative rates, corrected for identification inefficiency and background, can be combined and are (1.3 ± 0.4)% for (μ−e+ + μ−μ+)/μ− in neutrino interactions, and (1.2 ± 0.5)% for (μ+e− + μ+μ−)/μ+ antineutrino interactions. Eight out of the sixteen μ−ℓ+ events have a V0, leading to a corrected K0-multiplicity of 1.7 ± 0.7. No evidence is found for heavy-lepton production.

The study of K+p reactions at an incident momentum of 4.97 GeV/c suggests that the wide enhancement in the (Kππ)+ mass spectrum may be split into several resonant states. In particular, examination of the K∗(892)π decay mode indicates the existence of the states K∗(1230), K∗(1280) and K∗(1320), in addition to the well known K∗(1420). The K∗(1230) and K∗(1320) have the properties expected from 1+ states produced by 0+ exchange.

The search for light stops is of paramount importance, both in general as a promising path to the discovery of beyond the standard model physics and more specifically as a way of evaluating the success of the naturalness paradigm. While the LHC experiments have ruled out much of the relevant parameter space, there are "stop gaps", i.e., values of sparticle masses for which existing LHC analyses have relatively little sensitivity to light stops. We point out that techniques involving on-shell constrained M_2 variables can do much to enhance sensitivity in this region and hence help close the stop gaps. We demonstrate the use of these variables for several benchmark points and describe the effect of realistic complications, such as detector effects and combinatorial backgrounds, in order to provide a useful toolkit for light stop searches in particular, and new physics searches at the LHC in general.

Abstract Exposures of the Ne/H 2 filled Big European Bubble Chamber (BEBC) to a dichromatic neutrino (antineutrino) beam produced by 400 GeV protons of the CERN SPS yielded ∼ 3100 events with a negative, and ∼ 1100 with a positive, muon. The neutrino flux is determined from the muon flux in the shielding. Assuming a linear energy dependence of the cross section, the values σ E between 20 and 200 GeV are found to be 0.657 ± 0.012 (stat.) ± 0.027 (syst.) and 0.309 ± 0.009 (stat.) ± 0.013 (syst.) cm 2 (GeV nucleon) −1 , for neutrinos and antineutrinos, respectively. The scaling variable q 2 E decreases significantly with increasing energy both for neutrinos and antineutrinos.

Results are presented on the inclusive reactions pp → K0X, pp → ΛX and pp → ΛX at an incident antiproton momentum of 12 GeV/c in BEBC. The cross sections are studied as functions of the Feynman scaling variable x, the rapidity, the transverse momentum of the V0 and the missing mass squared. The dependence of the Λ and Λ polarization on x are also studied. Comparisons with proton-proton data at 12 GeV/c are also made. Finally, events with two detected V0 are analyzed in order to study correlations arising from the production of two strange neutral particles.

νe induced events obtained in a 200 GeV narrow-band beam have been studied and compared to the number expected from Ke3+ decay. Agreement is found between the expected and observed numbers allowing limits to be set on νe → νx mixing.

In a selected sample of 6770 charged current (CC) events of νp interactions with 〈Eν〉 = 43 GeV and 〈W〉 = 4.6 GeV, 359 K0, 180 Λ and 13 Λ have been observed, which corresponds to a corrected production rate at least one neutral strange particle in (17.4±0.8)% of the CC events. The ratio of the inclusive Λ to K0 production cross section is found to be 0.26±0.03. The number of CC events containing at least one K0 increases with increasing Eν and Q2, while the CC events containing at least one Λ remain practically constant. The fractions of the total hadronic energy carried by K0 and Λ are found to be approximately the same in νp as in ep and μp interactions. In the hadronic c.m.s., the K0 are produced mostly forwards, the Λ mostly backwards, with asymmetry parameters of +0.32±0.02 and −0.45±0.06, respectively. The total strange particle production cross section is estimated to be (25±4)% of the cross section for production of CC events with W>1.5 GeV and that for charm production (10±2)% of the CC cross section well above charm threshold (W>3 GeV). The production of the resonances K∗+ (890) and Σ+ (1385) has been observed. The production rate of K∗+ (890) is comparable to that of D∗+ (2009), above the corresponding thresholds.

An analysis is presented of the distribution of hadronic energy in neutrino and antineutrino neutral current interactions occurring in BEBC, filled with a neon-hydrogen mixture and exposed to the CERN-SPS narrow-band neutrino beam. This shows that the contributions by scalar or pseudo-scalar forms of the interaction are consistent with zero and pure V, A and V + A are excluded; there is good agreement with the Weinberg-Salam model.

The reactions (1) K+ p → K∗(1420)p and (2) K+p → K∗(1420)N∗(1236) are studied at 5 GeV/c incident K+ momentum. The simultaneous fitting of the Kπ and K∗(892)π decayy modes of the K∗ (1420) in the same production reaction makes it possible to eliminate 1− as the spin of the K∗(1420). The most likely K∗(1420) spin-parity assignment is 2+ although 3− cannot be excluded. The various decay branching ratios of the K∗(1420) are determined. The ratio of the K∗(892)π to the Kπ decay modes is found to be 0.9 ± 0.2. The peripheral production of the K∗(1420) seems to be due predominantly to vector-meson exchange in reaction (1) and to pion exchange in reaction (2).

Reconstructed mass variables, such as M 2, M 2C , M * , and M 2 , play an essential role in searches for new physics at hadron colliders. The calculation of these variables generally involves constrained minimization in a large parameter space, which is numerically challenging. We provide a C++ code, Optimass, which interfaces with the Minuit library to perform this constrained minimization using the Augmented Lagrangian Method. The code can be applied to arbitrarily general event topologies, thus allowing the user to significantly extend the existing set of kinematic variables. We describe this code, explain its physics motivation, and demonstrate its use in the analysis of the fully leptonic decay of pair-produced top quarks using M 2 variables.

This report emphasizes the comparison between supersymmetric models and experiments. A minimal theoretical introduction is included as a guide to the interpretation of results. The existing constraints from low energy measurements, accelerator searches (LEP, Tevatron and HERA) and non-accelerator searches for neutralinos are presented. Prospects for upgrades of these facilities and for the LHC and linear collider are summarized. Most discussions are made in the framework of the minimal supersymmetric standard model inspired by supergravity (MSUGRA). But alternatives such as gauge mediated supersymmetry breaking (GMSB), anomaly mediated supersymmetry breaking (AMSB), models with R-parity violation and even alternatives to supersymmetry are also briefly considered.

The ratio Rp of the neutral current to charged current cross sections has been measured in the BEBC bubble chamber filled with hydrogen and exposed to the CERN SPS wideband neutrino beam. It is found that an event selection in terms of the transverse momentum of the hadronic system is very effective in reducing backgrounds and enables Rp to be determined with an error of less than 10%. Combining the results from hydrrogen and isoscalar targets, the individual values of the coupling constants uL2 and dL2 are determined separately to be uL2 = 0.15 ± 0.06 and dL2 = 0.17 ± 0.08. The results are compatible with the standard SU (2) × U(1) model. The value of sin2θW determined from this experiment is 0.19 ± 0.04.

Production of charmed mesons has been observed in neutrino-hydrogen interactions in 285 000 photographs of BEBC exposed to the CERN wide-band neutrino beam. In ∼ 6000 charged current events, two events have been found each giving a three-constraint kinematical fit with production of only one strange particle, namely a K−, which is identified by its characteristic reaction K−p→Σ−π+. These events are thus examples of ΔS=−ΔQ reactions corresponding to charm production on a valence quark. For both events the effective mass of a (K− + pions) system is equal to the D0(1863) mass while the effective mass of this system plus a π+ is equal to the D∗+(2009) mass. The mass difference ΔM=M(D∗+)−MD0 is 145.2 ± 0.6 MeV. The first event is interpreted as νp→μ−pD∗+ and the second as νp→μ−pD∗+π+π−, both with D∗+→D0π+. The rate of inclusive D∗+ production has been estimated for all events by assuming that each negative track in turn is a K− and using the fact that the error on ΔM is small. It is found that the cross section σ(νp→μ−D∗++anything) relative to σ(νp→μ− + anything), above the D∗ threshold, is (4.1 ± 2.4)%.

Inclusive production of Λ and Λ in K+ p interactions is studied at incident momenta of 8.2 and 16.0 GeV/c. Cross sections and single-particle distributions are presented, the correlation between longitudinal and transverse momentum is investigated, and the dependence of average charge multiplicity on missing mass measured. For Λ production, early scaling is observed in the target fragmentation region when the data are presented in terms of (M2-Mth2)/s and t, where Mth is the threshold value of the missing mass M. Furthermore, a triple-Regge analysis in these variable yields an effective exchange trajectory which passes through the K, Q and L mesons. There is evidence for beam fragmentation in Λ and Λ production, but the contributions seem not to be dominant in the fragmentation region. Nevertheless, the parameter values in a triple-Regge description are estimated, and together with those for target fragmentation in Λ production, provide a complete description of the fragmentation contributions to the two reactions. Integration of the resultant distribution functions over the complete Chew-Low plot yields fragmentation cross sections increasing approximately as log s; in addition the observed features of the x, pL and pT2 projections and of the pL-pT correlation are well-described in the fragmentation regions. Central production contributions are isolated by subtracting the calculated fragmentation distributions

The cross sections for ν and ν neutral current interactions for which the hadron energy is >15 GeV have been measured. These results, and the ratios of neutral current to charged current cross sections, are in agreement with the Weinberg-Salam model. Values of sin2θW have been obtained both with and without the use of a parameterisation for the hadronic part of the interaction; the values are in good agreement with each other and the preferred result, that obtained by the method independent of hadronic models, is sin2θW = 0.22 ± 0.05.

A measurement of the Higgs boson Yukawa coupling to the top quark is presented using proton-proton collision data at $\sqrt{s} =$ 13 TeV, corresponding to an integrated luminosity of 137 fb$^{-1}$, recorded with the CMS detector. The coupling strength with respect to the standard model value, $Y_\mathrm{t}$, is determined from kinematic distributions in $\mathrm{t\bar{t}}$ final states containing ee, $μμ$, or e$μ$ pairs. Variations of the Yukawa coupling strength lead to modified distributions for $\mathrm{t\bar{t}}$ production. In particular, the distributions of the mass of the $\mathrm{t\bar{t}}$ system and the rapidity difference of the top quark and antiquark are sensitive to the value of $Y_\mathrm{t}$. The measurement yields a best fit value of $Y_\mathrm{t} =$ 1.16 $^{+0.24}_{-0.35}$, bounding $Y_\mathrm{t}$ $\lt$ 1.54 at a 95% confidence level.

A systematic analysis is presented on the reaction K+p→K∗0 (890) Δ++ for nine incident momenta between 4.6–16.0 GeV/c. Cross sections, differential cross sections and vector meson single density matrix elements are given. As a function of energy, little if any change is observed in either the shapes of the differential cross sections or in the values of the density matrix elements. The data are interpreted in terms of current ideas on t-channel exchange mechanisms.

Results are given on the comparison of the predictions of the multiperipheral model of Chan, Loskiewicz and allison with the experimental data obtained from a study of the interactions of 5 GeV/c K+ mesons with protons. Comparisons have been made in the three-, four-, five- and six-body final states containing a proton, kaon and pions. With the addition of resonance production to the model, adequate predictions of experimental distributions are obtained. An attempt is made to describe the energy variation of the three- and four-body final-state cross sections.

We consider SUSY-like events with two decay chains, each terminating in an invisible particle, whose true energy and momentum are not measured in the detector. Nevertheless, a useful educated guess about the invisible momenta can still be obtained by optimizing a suitable invariant mass function. We review and contrast several proposals in the literature for such ansatze: four versions of the M T 2-assisted on-shell reconstruction (MAOS), as well as several variants of the on-shell constrained M 2 variables. We compare the performance of these methods with regards to the mass determination of a new particle resonance along the decay chain from the peak of the reconstructed invariant mass distribution. For concreteness, we consider the event topology of dilepton $$ t\overline{t} $$ events and study each of the three possible subsystems, in both a $$ t\overline{t} $$ and a SUSY example. We find that the M 2 variables generally provide sharper peaks and therefore better ansatze for the invisible momenta. We show that the performance can be further improved by preselecting events near the kinematic endpoint of the corresponding variable from which the momentum ansatz originates.

Abstract The prompt electron neutrino and muon neutrino fluxes from proton copper interactions at 400 GeV/c proton momentum have been measured. The asymmetry between the prompt electron (anti) neutrino and the prompt muon (anti) neutrino event rates above 20 GeV is A e μ = (N e − N μ (N c + N μ ) = 0.07 ± 0.08 corresponding to an Ne/Nμ ratio of 1.14−0.16−0.19. The cross section weighted charge asymmetry for electrons and muons combined is A ν ν = 0.15 ± 0.08 . The number of D decays into ν e and ν μ is (4.1 ± 0.9) × 10 −4 per incident proton. No evidence for ντ interactions was found.

The ratios of neutral current to charged current cross sections of neutrino and antineutrino interactions in heavy Ne/H2 mixture have been measured in BEBC. The beam was the CERN SPS 200 GeV/c narrow band beam. The ratios were obtained using a cut in the transverse momentum of the hadronic system. In the standard Glashow-Salam-Weinberg model, our results correspond to the value of sin2 θw = 0.182 ± 0.020 ± 0.012. By combining this experiment with data from a hydrogen target the coupling constants uL2 and L2 are found to be 0.15 ± 0.04 and 0.19 ± 0.05, respectively.

The inclusive production of K0's and Λ's has been investigated in neutrino and antineutrino interactions in BEBC, filled with a neon-hydrogen mixture. The inclusive rates for the 3083 (1022) ν (ν) induced charged current events are (23.0 ± 1.7)% ((21.9 ± 2.8)%) for K0's and (5.7 ± 0.7)% ((6.5 ± 1.2)%) for Λ's. The general behaviour of the K0's and Λ's is found to be similar to that in νp interactions and π+p interactions at lower 〈W〉. In the hadronic c.m.s. K0's are produced mostly forwards, Λ's predominantly in the backward hemisphere. The data indicate that K0's produced in ν interactions on average carry a larger fraction of the total available momentum than those in ν induced reactions. The dependences of the average transverse momentum on the variables Q2, W2 and Bjorken x are presented.

Data from an exposure of BEBC filled with hydrogen to a wideband neutrino beam are analysed to yield the structure function Fvp2(x) for x > 0.2. Using our results in combination with data from electron-proton and muon-proton scattering, the quark density ratio d/u is determined as a function of x. The dominance u at large x is clearly seen. The results are compared with theoretical predictions.

An analysis of the transverse momentum distributions of secondary hadrons produced in neutrino-proton charged current interactions is presented. It is found thatparticles going forward in the hadronic c.m.s. have a different behaviour from those going backward. A rise of the average transverse momentum squared as a function of both the invariant mass of the hadronic system and the fractional energy carried by the hadron in the c.m. frame, is observed. The result is not in good agreement with the predictions of a QCD based model if the non-perturbative parts are forward-backward symmetric. Using events with no missing neutral particles in the final state the average primordial transverse momentum squared of the quark inside the nucleon is estimated to be ∼0.3 GeV2/c2.

We report the evidence for a narrow charged peak (5.5 s.d.), which we suggest calling the I, in the 6-prong-V0 topology of pp interactions at 12 GeV/c. The mass, widht and the product of cross section σI times the branching ratio BR into the final state (Ksoτ±τ+τ− are found to be: MI=2.60 ± 0.01 GeV/c2, ΓI⩽0.018 GeV/c2, σI·BR≈20 μbarn

The inclusive same-sign dilepton channel is already recognized as a promising discovery signature for supersymmetry in the early days of the LHC. We point out that it can also be used for precision measurements of sparticle masses after the initial discovery. As an illustration, we consider the LM6 CMS study point in minimal supergravity, where the same-sign leptons most often result from chargino decays to sneutrinos. We discuss three different techniques for determining the chargino and sneutrino masses in an inclusive manner, i.e., using only the two well measured lepton momenta, while treating all other upstream objects in the event as a single entity of total transverse momentum ${\stackrel{\ensuremath{\rightarrow}}{P}}_{T}$. This approach takes full advantage of the large production rates of colored superpartners, but does not rely on the poorly measured hadronic jets, and avoids any jet combinatorics problems.

A review is presented of the experimental status of the quark structure of the nucleon. It is based mainly on results from the CERN muon experiments, but results from deep inelastic electron and neutrino scattering and e+ e- annihilation are included where appropriate. The data are compared to predictions of the Quark Parton Model and Quantum Chromodynamics (QCD) and allow a determination of the QCD strong coupling constant αs and the QCD mass scale parameter Λ. The properties of hadronic final states produced in the fragmentation of quarks and the effects of weak-electromagnetic interference in deep inelastic scattering are also reviewed.

The average transverse momentum squared, 〈p⊥2〉, of hadrons is studied as a function of W2 and of Q2 for ν and ν interactions on an isoscalar target. An increase of 〈p⊥2〉 with W2 is observed for the hadrons emitted forward in the hadronic c.m.s. The p⊥ dependence of the fragmentation function is found to factorise from the structure function at fixed W, but does not factorise at fixed Q2. Unlike the case of forward-going particles, the 〈p⊥2〉 of hadrons going backward in the c.m.s. shows no strong dependence on W2.

In about 30 000 identified events produced in K+p reactions at incident momenta 3.0, 3.5 and 5.0 GeV/c we have searched for the production of Z∗'s. i.e. S = +1, T = 0 or 1 baryonic resonances. No indication has been found in the examination of the various available production reactions of Z∗ decaying with visible modes. Upper limits for the corresponding cross-sections are generally less than 30 μb at 3.0 and 3.5 GeV/c. 10 μb at 5.0 GeV/c. Summing for a given production reaction over all possible Z∗ decay modes. i.e. performing a missing mass type of analysis, does not revel any further evidence.

We have determined the cross section for elastic K+π−→K+π−, and charge exchange, K+π−→K0π0, scattering using the Chew-Low extrapolation method, for Kπ masses up to 1.35 GeV. This has been achieved by using 3026 events of the type K+p→K+π−N∗ (1236) and 1246events of the type K+p→K0π0N∗ (1236) obtained in bubble chamber exposures at CERN. The cross section exhibits the known K∗ (892) resonance shape. A similar study for the K+π+→K+π+ elastic scattering has been attempted. The partial wave expansion coefficients up to 〈Y40〉 (without off-shell correction) have been studied as a function of the Kπ masses.

We present a study of six- and seven-body final states among the K+p interactions at 5 GeV/c incident K+ momentum. Results on cross sections, resonance and single-particle productions are given. Charge dependent angular correlations for pairs of pions occur as in pp and π+p interactions (the so called GGLP effect). In contrast, no dependence on the charge is observed in the angular correlations between kaons and pions. The influence of the production of K∗ and N∗ resonances on these angular correlations is investigated. The predictions of a multi-Regge Model (CŁA) are compared to the experimental results.

Two examples of charmed baryon production by neutrinos have been observed in BEBC filled with hydrogen. Both events fit uniquely the reaction νp → μ−pK−π+π+ and thus apparently violate the ΔS = ΔQ rule. None of the appropriate mass combinations is consistent with the mass values of the D0 and D+ mesons. However, for the mass combinations of the pK−π+ systems, values of (2.285 ± 0.005) GeV and (2.280 ± 0.003) GeV are found for event 1 and 2, respectively. These values agree with the mass of (2.285 ± 0.006) GeV for the Λc+ charmed baryon determined recently in e+e− collisions at SLAC.

K+p interactions at an incident momentum of 4.97 GeV/c show evidence for a new Kππ resonant state K∗(1660), at a mass of (1660 ± 10) MeV, full width (60 ± 20) MeV. Decays into K∗(1420)π and K∗(892)π are found. In addition there is an indication of a Kπ decay mode.

A search for exclusive two-photon production via photon exchange in proton-proton collisions, pp $\to$ p$γγ$p with intact protons, is presented. The data correspond to an integrated luminosity of 9.4 fb$^{-1}$ collected in 2016 using the CMS and TOTEM detectors at a center-of-mass energy of 13 TeV at the LHC. Events are selected with a diphoton invariant mass above 350 GeV and with both protons intact in the final state, to reduce backgrounds from strong interactions. The events of interest are those where the invariant mass and rapidity calculated from the momentum losses of the forward-moving protons matches the mass and rapidity of the central, two-photon system. No events are found that satisfy this condition. Interpreting this result in an effective dimension-8 extension of the standard model, the first limits are set on the two anomalous four-photon coupling parameters. If the other parameter is constrained to its standard model value, the limits at 95% CL are $\lvertζ_1\rvert$ $\lt$ 2.9 $\times$ 10$^{-13}$ GeV$^{-4}$ and $\lvertζ_2\rvert$ $\lt$ 6.0 $\times$ 10$^{-13}$ GeV$^{-4}$.

Neutrino and antineutrino interactions with two muons in the final state have been studied by the CCFR collaboration in the Fermilab Tevatron neutrino beam. The rate of neutrino- and antineutrino-induced prompt same-sign dimuon production in steel was measured using a sample of 220 μ−μ− events and 15 μ+μ+ events with Pμ > 9 GeV/c, and energies between 30 GeV and 600 GeV. After background subtraction, the prompt rate of same-sign dimuon production is (0.53 ± 0.24) × 10−4 per νμ charged-current event and (0.52 ± 0.33) × 10−4perνμ charged-current event. After demanding Pμ1 ≥ 9 GeV/c, Pμ2 ≥ 5 GeV/c and 30 ≤ Eν ≤ 600 GeV a sample of 5044 νμ 1062 νμinduced μ∓ μ± events are observed. The data support the slow rescaling model of charm production with a value of mc = 1.31 ± .24 GeV/c2. The CKM matrix element Vcd=.209±0.012 and the nucleon strangeness content, ηε=.064−0.00065+0.00075 are measured with the strange sea x distribution found to be softer than its non-strange counterpart. The first measurements of the Q2 dependence of the strange quark densities, ϰs(ϰ), are also presented.

Results are presented on the production of K0, K∗+(892) and π± in the interaction K+p → K0 + π± + anything at 8.2 and 16 GeV/c. The π± forward and backward dσdx distributions are of the form exp (−Ax). It is shown that the forward and backward values of A in a quark-quark rest frame change after subtraction of the contributions due to the resonances produced. A comparison is made of dσdx inclusive cross sections for K0's and K∗+(892) with the predictions of a quark model in the fragmentation region. The experimental cross section matches the theoretical predictions for K0's but disagree with those for K∗+(892).

The purpose of this review is to investigate what kind of physics can be extracted at the LHC, assuming a discovery is made in events with missing transverse momentum, as generically expected in supersymmetry (SUSY) with R-parity conservation. To set the scene, we first discuss the collider phenomenology of the six possible electroweakino benchmark scenarios, as they provide valuable insight into what one might be facing at the LHC. We review the existing methods for mass reconstruction from measured kinematic endpoints in the distributions of suitable variables, e.g., the invariant masses of various sets of visible decay products, as well as the $M_{T2}$ and the $M_2$ types of variables. We propose to extend the application of these methods to the various topologies of fully hadronic final states, possibly with hadronically reconstructed massive bosons (W, Z or h). We test the idea with a simplified simulation of events in the main electroweakino benchmark scenarios. We find that the fully hadronic events allow the complete determination of the relevant mass spectrum. For comparison, we also review the potential of the standard kinematic endpoint methods for final states involving leptons from the decays of (on-shell or off-shell) sleptons. We find that with 300 $fb^{-1}$, the statistics for the leptonic events is very marginal and they look less promising than the fully hadronic channels. This corresponds to a complete reversal of the usual paradigm, where leptonic events comprised the gold-plated SUSY channels. Finally, we put together all available information and summarize what level of understanding of the underlying physics can be achieved. We show that, as a by-product of the mass reconstruction, it is also possible to determine the production cross sections and decay branching ratios, which in turn enable us to pinpoint the underlying model.

We present results on the analysis of the quasi three-body reaction K+p → K+π−N∗++ obtained from bubble chamber exposures at 5 GeV/c incident K+ momentum. We have applied a method of analysis based on the study of the longitudinal phase space plot recently proposed by Van Hove. Evidence for the existence of π− mesons with a four-momentum transfer peaked at small values is shown. (Events contributing to this peak correspond to the cross section of about 80 μb.) The difficulties in explaining this result in terms of the double-particle exchange model are discussed.

We present the data on the Λ(Σ) events produced in final states of K+p interactions at 8.25 GeV/c. Cross sections for Yo production are given for most final states obtained in this experiment, and the results at other energies are listed for comparison. No significant enhancement is seen in the Yo N mass distributions while there is some indication of the production of Y∗ (1385) and N∗ (1236) in the Λπ and Nπ systems respectively. An attempt at the description of the reaction K+p→Λpp in terms of a five-point Veneziano amplitude is also included.

In a neutrino-proton experiment performed with the bubble chamber BEBC, which was exposed to the wide-band neutrino beam of the CERN SPS, the semi-inclusive reaction νp→μ−h± + X is studied where h± is a hadron of a chosen type. Non-factorization of the semi-inclusive cross section is investigated in terms of double moments with respect to Bjorken-x and the energy fraction z and comparisons are made with predictions of perturbative QCD in next-to-leading order.

Results are presented on an analysis of the reaction K+p → K∗+ (890) p at 16 GeV/c and compared with data at lower incident momenta and with corresponding results for the reaction K−p → K∗− (890) p. It is found for both reactions that the energy dependence of the cross section exhibits a simple (p−nlab behaviour.

We introduce a set of CMSSM benchmark scenarios that take into account the constraints from LEP, Tevatron, $b \to s γ$, $g_μ- 2$ and cosmology. The benchmark points are chosen to span the range of different generic possibilities, including focus-point models, points where coannihilation effects on the relic density are important, and points with rapid relic annihilation via direct-channel Higgs poles, as well as points with smaller sparticle masses. We make initial estimates of the physics reaches of different accelerators, including the LHC, and $e^+ e^-$ colliders in the sub- and multi-TeV ranges. We stress the complementarity of hadron and lepton colliders, with the latter favoured for non-strongly-interacting particles and precision measurements.

Abstract We have analyzed the reaction K + p → K + π − N ∗++ at 5 GeV/ c K + primary momentum, from the point of view of the double-peripheral model. The distributions of four-momentum transfers t′ pN ∗ and t′ KK (t′=t t t min ) have been studied as functions of the masses of the N ∗++ π − and K + π − systems. We have found that the observed correlations cannot be explained adequately by the present version of the Chan-oskiewicz-Allison model. The disagreement is particularly striking for the low N ∗++ π − mass region, where the data show peripheral production of the N ∗++ , contrary to the prediction of the model. The implications of the results for the double peripheral model are discussed.

The final states corresponding to the reaction K+p → KNπππ are studied at 5.0 GeV/c incident momentum. The general characteristics of these reactions are given. A more detailed study is made of resonance production. The more abundantly produced resonances are K∗(892), Δ(1236), ϱ, ω, η, K∗(1420), N∗(1520) and N∗(1700). Fits to the multidimensional space of effective masses show that for the final state Kopπ+π−π−, more than 30% of the reaction proceeds through quasi two-body intermediate states, and that more than 88% proceeds through the production of at least one resonance. Some evidence is found for the production of other resonances such as K∗(1660) → K3π, Δ(1920) → → pπ+π+π− and N∗(2064) → pπ+π−πo. Several example of cascade decays are found, but no direct decay into more than three bodies is observed

A search for charmed particles produced in π−p exclusive reactions at 19 GeV/c incident beam momentum has been carried out with the Omega spectrometer at CERN. Three million interactions were recorded with a trigger which required a forward K− or p with transverse momentum greater than 0.5 GeV/c. An additional two million triggers were recorded with a forward K+ or proton, with no transverse momentum restriction. Analysis of the four-constraint final states K+K−π−p and K+K−π+π−π−p shows no evidence for the associated production of charmed particles. The upper limits for the product of production cross sections and the two charmed particle decay branching ratios are below 100 nb for most of the channels. The experiment was sensitive over a wide range of production angles.

Abstract In bubble chamber experiments at intermediate and high energies, a large fraction of one constraint fit events cannot be identified unambiguously. Studying this problem from the kinematical point of view, we found that certain types of ambiguity can be related to well defined regions of laboratory momentum plots. A relation is given between the χ 2 of a fit and the square of the pull on the missing mass squared of the corresponding hypothesis. This feature is used to treat the ambiguities in a rigorous way. A computer program has been written, which calculates the fractions of events, corresponding to the different ambiguities. Methods are indicated to correct the cross sections.

The four LEP experiments ALEPH, DELPHI, L3 and OPAL successfully recorded e+e- collision data during the years 1989 to 2000. As part of the ordinary evolution in High Energy Physics, these experiments can not be repeated and their data is therefore unique. This article briefly reviews the data preservation efforts undertaken by the four experiments beyond the end of data taking. The current status of the preserved data and associated tools is summarised.

A search for long-lived particles (LLPs) produced in association with a Z boson is presented. The study is performed using data from proton-proton collisions with a center-of-mass energy of 13 TeV recorded by the CMS experiment during 2016-2018, corresponding to an integrated luminosity of 117 fb$^{-1}$. The LLPs are assumed to decay to a pair of standard model quarks that are identified as displaced jets within the CMS tracker system. Triggers and selections based on Z boson decays to electron or muon pairs improve the sensitivity to light LLPs (down to 15 GeV). This search provides sensitivity to beyond the standard model scenarios which predict LLPs produced in association with a Z boson. In particular, the results are interpreted in the context of exotic decays of the Higgs boson to a pair of scalar LLPs (H $\to$ SS). The Higgs boson decay branching fraction is constrained to values less than 6% for proper decay lengths of 10-100 mm and for LLP masses between 40 and 55 GeV. In the case of low-mass ($\approx$15 GeV) scalar particles that subsequently decay to a pair of b quarks, the search is sensitive to branching fractions $\mathcal{B}$(H $\to$ SS) $\lt$ 20% for proper decay lengths of 10-50 mm. The use of associated production with a Z boson increases the sensitivity to low-mass LLPs of this analysis with respect to gluon fusion searches. In the case of 15 GeV scalar LLPs, the improvement corresponds to a factor of 2 at a proper decay length of 30 mm.

A measurement of inclusive four-jet production in proton-proton collisions at a center-of-mass energy of 13\TeV is presented. The transverse momenta of jets within $\lvert\eta\rvert \lt$ 4.7 reach down to 35, 30, 25, and 20 GeV for the first-, second-, third-, and fourth-leading jet, respectively. Differential cross sections are measured as functions of the jet transverse momentum, jet pseudorapidity, and several other observables that describe the angular correlations between the jets. The measured distributions show sensitivity to different aspects of the underlying event, parton shower, and matrix element calculations. In particular, the interplay between angular correlations caused by parton shower and double-parton scattering contributions is shown to be important. The double-parton scattering contribution is extracted by means of a template fit to the data, using distributions for single-parton scattering obtained from Monte Carlo event generators and a double-parton scattering distribution constructed from inclusive single-jet events in data. The effective double-parton scattering cross section is calculated and discussed in view of previous measurements and of its dependence on the models used to describe the single-parton scattering background.

Data taken by DELPHI during the 1995 and 1996 LEP runs have been used to search for the supersymmetric partners of electron, muon and tau leptons and of top and bottom quarks. The observations are in agreement with standard model predictions. Limits are set on sfermion masses. Searches for long lived scalar leptons from low scale supersymmetry breaking models exclude stau masses below 55 GeV/c2 at the 95% confidence level, irrespective of the gravitino mass.

Moments of the quark-singlet fragmentation function are determined from measured moments of the u-quark fragmentation functions D±u(z, q2) into positive and negative hadrons in the reaction νp→μ− + hadrons. The q2 dependence of these moments is investigated in the framework of leading-order QCD and estimates are given for the moments of the gluon fragmentation function. The results are based on a sample of θ 7800 charged current events from a BEBC neutrino-hydrogen experiment.

We study the scaling properties of the semi-inclusive reactions K+p → K0 + n (charged) + X0 (neutral) measuring the momentum spectra of K0-mesons for a given number of prongs n. Distributions of the particle density ω(dσn/dpL)/σn for the inclusive K0 at n = 2 and n = 4 show evidence for limited scaling at 5.0, 8.2 and 16 GeV/c incident K+ momenta.

The reaction K+p → Δ++(1236) + anything is studied at beam momentum 8.2 GeV/c. The spin density matrix of the Δ++ shows than one-pion exchange is dominant at low-momentum transfer. The total and topological K+π− cross sections have been determined by a Chew-Low extrapolation in the cm energy range from threshold to 1.8 GeV, using three different methods of extrapolation.

In a study of K+p interactions at 5 GeV/c, evidence is found for production of a baryon resonance with S = 0, I = 12, mass 1575 ± 19 MeV, width 128 ± 20 MeV. The observed decay branching ratio makes it plausible to identify this baryon with the S11 resonance found previously at 1570 MeV in the phase shift analysis of πp scattering.

An inclusive search for low mass SUSY using the top plus missing transverse energy signature at CMS is presented. A kinematic fit with the top and W masses as constraints is utilized to reconstruct the top in all-hadronic final states. A 5σ excess can be observed with ∼250 pb -1 at a particular low mass SUSY point. With the same analysis selection the 5σ discovery reach contours in the mSUGRA parameter space for 1 and 10 fb -1 are obtained.