A. Santoro

A model-independent partial-wave analysis of the S-wave component of the Kπ system from decays of D+ mesons to the three-body K−π+π+ final state is described. Data come from the Fermilab E791 experiment. Amplitude measurements are made independently for ranges of K−π+ invariant mass, and results are obtained below 825 MeV/c2, where previous measurements exist only in two mass bins. This method of parametrizing a three-body decay amplitude represents a new approach to analyzing such decays. Though no model is required for the S-wave, a parametrization of the relatively well-known reference P- and D-waves, optimized to describe the data used, is required. In this paper, a Breit-Wigner model is adopted to describe the resonances in these waves. The observed phase variation for the S-, P-, and D-waves do not match existing measurements of I=12 K−π+ scattering in the invariant mass range in which scattering is predominantly elastic. If the data are mostly I=12, this observation indicates that the Watson theorem, which requires these phases to have the same dependence on invariant mass, may not apply to these decays without allowing for some interaction with the other pion. The production rate of K−π+ from these decays, if assumed to be predominantly I=12, is also found to have a significant dependence on invariant mass in the region above 1.25 GeV/c2. These measurements can provide a relatively model-free basis for future attempts to determine which strange scalar amplitudes contribute to the decays.2 MoreReceived 27 July 2005Corrected 24 August 2006DOI:https://doi.org/10.1103/PhysRevD.73.032004©2006 American Physical Society

We present asymmetries between the production of D+ and D− mesons in Fermilab experiment E791 as a function of xF and pt2. The data used here consist of 74000 fully-reconstructed charmed mesons produced by a 500 GeV/c π− beam on C and Pt foils. The measurements are compared to results of models which predict differences between the production of heavy-quark mesons that have a light quark in common with the beam (leading particles) and those that do not (non-leading particles). While the default models do not agree with our data, we can reach agreement with one of them, PYTHIA, by making a limited number of changes to parameters used.

We measure forward cross sections for production of ${D}^{+}$, ${D}^{0}$, ${D}_{s}$, ${D}^{*+}$, and ${\ensuremath{\Lambda}}_{c}$ in collisions of ${\ensuremath{\pi}}^{\ifmmode\pm\else\textpm\fi{}}$, ${K}^{\ifmmode\pm\else\textpm\fi{}}$, and $p$ on a nuclear target. Production induced by different beam particles is found to be the same within statistics. Strange and baryonic final states are seen to contribute appreciably to the total charm cross section, which our measurements indicate is larger than but consistent with QCD predictions. The energy dependence mapped out by these and previous measurements is consistent with theory. Leading-particle asymmetry measurements for $K$ and $p$-induced charm production are also presented.

The decay ${D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{e}^{+}{\ensuremath{\nu}}_{e}$ has been studied in the Fermilab photoproduction experiment E691. The ratio of branching ratios, $\frac{B({D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{*0}{e}^{+}{\ensuremath{\nu}}_{e})}{B({D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+})}$, is found to be 0.49\ifmmode\pm\else\textpm\fi{}0.04 \ifmmode\pm\else\textpm\fi{}0.05, corresponding to a ${D}^{+}\ensuremath{\rightarrow}{\overline{K}}^{*0}{e}^{+}{\ensuremath{\nu}}_{e}$ branching ratio of (4.5\ifmmode\pm\else\textpm\fi{}0.7\ifmmode\pm\else\textpm\fi{}0.5)%. The branching ratio to the nonresonant ${({K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+})}_{\mathrm{NR}}e{\ensuremath{\nu}}_{e}$ final state is found to be less than 0.7% at the 90% confidence level. The ${\overline{K}}^{*0}$ mesons have a ratio of longitudinal to transverse polarization of 2.4${\ifmmode\pm\else\textpm\fi{}}_{0.9}^{1.7}$\ifmmode\pm\else\textpm\fi{}0.2.

Coincidence-site lattices are characterized mathematically, in the general case, by a method that can be applied to a pair of original lattices of any symmetry, either metrically identical or metrically different, does not involve inspection and is readily adaptable to computer calculations. The procedure is illustrated by several numerical examples. The proposed characterization of coincidence-site lattices is based on the theory of derivative lattices and makes extensive use of the concepts of superlattice and sublattice. Appended is a simple procedure for determining the transformation matrices needed to generate superlattices and sublattices of any multiplicity.

We measure the relative cross sections for D mesons produced in interactions of ${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ and ${\mathrm{\ensuremath{\pi}}}^{+}$ beams with targets of Be, Cu, Al, and W. The measurement is based on 1400 fully reconstructed decays of the types ${\mathit{D}}^{0}$\ensuremath{\rightarrow}${\mathit{K}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{+}$, ${\mathit{D}}^{+}$\ensuremath{\rightarrow}${\mathit{K}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{+}$, and charge conjugates. We find that the cross section for the production of both neutral and charged D's by either ${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$ or ${\mathrm{\ensuremath{\pi}}}^{+}$ is well fitted by the form ${\mathit{A}}^{\mathrm{\ensuremath{\alpha}}}$ where A is the atomic mass and \ensuremath{\alpha}=1.00\ifmmode\pm\else\textpm\fi{}0.05\ifmmode\pm\else\textpm\fi{}0.02, where the errors are statistical and systematic, respectively. There is no significant dependence of \ensuremath{\alpha} on the transverse or longitudinal momentum of the D meson or on the charge of either the incident pion or the produced D mesons.

We measure the differential cross sections with respect to Feynman $x$ ( ${x}_{F}$) and transverse momentum ( ${p}_{T}$) for $\ensuremath{\pi}$, $K$, and $p$-induced charm meson production using fully reconstructed ${D}^{+}$, ${D}^{0}$, and ${D}_{s}$ decays. The shapes of these cross sections are compared to the theoretical predictions for charm quark production of next-to-leading order perturbative QCD using modern parametrizations of the pion and nucleon parton distributions. We observe the differences expected in production induced by projectiles with different gluon distributions, harder distributions being indicated for mesons than for protons.

We report on a Dalitz-plot analysis of 250 ${\mathit{D}}^{\ifmmode\pm\else\textpm\fi{}}$ and 290 ${\mathit{D}}_{\mathit{s}}^{\ifmmode\pm\else\textpm\fi{}}$ decays into ${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$. We measure the relative rate for each charmed meson decaying into \ensuremath{\varphi}${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$, K\ifmmode\bar\else\textasciimacron\fi{}${\mathrm{*}}^{0}$(K${\mathrm{*}}^{0}$)${\mathit{K}}^{\ifmmode\pm\else\textpm\fi{}}$, and nonresonant ${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$, and determine the ${\mathit{D}}_{\mathit{s}}^{\ifmmode\pm\else\textpm\fi{}}$ mass. In addition, we measure the relative branching ratios for the decays of ${\mathit{D}}_{\mathit{s}}^{\ifmmode\pm\else\textpm\fi{}}$ and ${\mathit{D}}^{\ifmmode\pm\else\textpm\fi{}}$ into \ensuremath{\varphi}${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$ and nonresonant ${\mathit{K}}^{+}$${\mathit{K}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{+}$${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$${\mathrm{\ensuremath{\pi}}}^{\ifmmode\pm\else\textpm\fi{}}$.

We measure the differential cross section with respect to Feynman-x (xF) and transverse momentum (PT) for charm meson production using targets of Be, Al, Cu, and W. In the range 0.1<xF<0.7, dσ/dxF is well fit by the form (1-xF)n with n=3.9±0.3. The difference between n values for D− and D+ is 1.1±0.7. However, we find an asymmetry of 0.18±0.06 favoring the production of D− compared to D+. In the lower PT range, <2 GeV, dσ/dP2T is well fit by the form exp(-b×P2T) with b=1.03±0.06 GeV−2, while in the higher PT range, 0.8 to 3.6 GeV, it is well fit by the form exp(-b’×PT) with b’=2.76±0.08 GeV−1. The shape of the differential cross section has no significant dependence on atomic mass of the target material.Received 8 October 1992DOI:https://doi.org/10.1103/PhysRevLett.69.3147©1992 American Physical Society

This book contains the proceedings of the topics covered during the fifth Jorge Andre Swieca Summer School. The first part of the book collects the material devoted to quantum field theory. There were four courses on methods in Field Theory; H. O. Girotti lectured on constrained dynamics, R. Jackiw on the Schrodinger representation in Field Theory, S.-Y. Pi on the application of this representation to quantum fields in a Robertson-Walker spacetime, and L. Vinet on Berry Connections. There were three courses on Conformal Field Theory: I. Todorov focused on the problem of construction and classification of conformal field theories. Lattice models, two-dimensional S matrices and conformal field theory were looked from the unifying perspective of the Yang-Baxter algebras in the lectures given by M. Karowski. Parasupersymmetric quantum mechanics was discussed in the lectures by L. Vinet. Besides those courses, there was an introduction to string field theory given by G. Horowitz. There were also three seminars: F. Schaposnik reported on recent applications of topological methods in field theory, P. Gerbert gave a seminar on three dimensional gravity and V. Kurak talked on two dimensional parafermionic models. The second part of this proceedings is devoted to phenomenology. There were three coursesmore » on Particle Physics: Dan Green lectured on collider physics, E. Predrazzi on strong interactions and G. Cohen-Tanoudji on the use of strings in strong interactions.« less

We present a model for ABC production, which is experimentally observed in the missing mass spectrum of the reaction dp → 3He + (MM)°. The reaction is assumed to be split in two successive steps, namely: (i) N1p → di1 followed by (ii) N2di → 3Heπ 2, N1 and N2 being the two nucleons of the incident deuteron and di an intermediate deuteron. The total amplitude is factorized into the product of the two amplitudes of reactions (i) and (ii). We know that at low energy these two reactions are dominated by a Δ production. This implies that the total cross sections are given by Breit-Wigner type formulae and that the angular distributions are peaked in the backward and forward directions. The two main results are: (i) at given incident energy, the ABC effect results from the angular distribution of the two intermediate reactions; (ii) the energy dependence of the ABC is deduced from those of the intermediate processes. The resulting fits are generally excellent when the Fermi motion in the initial deuteron is taken into account.

In view of the High Luminosity upgrade of the CERN LHC, the forward CMS Muon spectrometer will be extended with two new stations of improved Resistive Plate Chambers (iRPC) covering the pseudorapidity range from 1.8 to 2.4. Compared to the present RPC system, the gap thickness is reduced to lower the avalanche charge, and an innovative 2D strip readout geometry is proposed. These improvements will allow iRPC detector to cope with higher background rates. A new Front-End-Board (FEB) is designed to readout iRPC signals with a threshold as low as 30 fC and an integrated Time Digital Converter with a resolution of 30 ps. In addition, the communication bandwidth is significantly increased by using optical fibers. The history, final design, certification, and calibration of this FEB are presented.

This paper presents measurements of the production of Ds- mesons relative to Ds+ mesons as functions of x_F and square of p_t for a sample of 2445 Ds decays to phi pi. The Ds mesons were produced in Fermilab experiment E791 with 500 GeV/c pi- mesons incident on one platinum and four carbon foil targets. The acceptance-corrected integrated asymmetry in the x_F range -0.1 to 0.5 for Ds+- mesons is 0.032 +- 0.022 +- 0.022, consistent with no net asymmetry. The results, as functions of x_F and square of p_t, are compared to predictions and to the large production asymmetry observed for D+- mesons in the same experiment. These comparisons support the hypothesis that production asymmetries come from the fragmentation process and not from the charm quark production itself.

We present a measurement of asymmetries in the production of Λc+ and Λc− baryons in 500 GeV/c π−-nucleon interactions from the E791 experiment at Fermilab. The asymmetries were measured as functions of Feynman x (xF) and transverse momentum squared (pT2) using a sample of 1819±62 Λc's observed in the decay channel Λc+→pK−π+. We observe more Λc+ than Λc− baryons, with an asymmetry of (12.7±3.4±1.3)% independent of xF and pT2 in our kinematical range (−0.1⩽xF⩽0.6 and 0.0⩽pT2⩽8.0 (GeV/c)2). This Λc asymmetry measurement is the first with data in both the positive and negative xF regions.

To describe diffractive dissociation processes we propose a three-component Deck model including particle exchange in all the channels of the dissociation subprocess. Reggeization is performed by taking duality constraints into account. This dual reggeization preserves the interferences between the three components which are present in the Born approximation and which allow one to understand the observed strong mass-slope correlation. The model is applied with success to nucleon diffractive dissociation.

We report results on Ds± decays into the final states π+π−π±π0 and K+K−π±π0 from the Fermilab charm photoproduction experiment E691. For the former decay we search for ηπ± and ωπ± components, and for the latter, we measure the relative rate for decays into φπ±π0 and non-resonant K±K−π±π0. We also present limits for Cabibbo-suppressed D± decays into these final states, and measure the Cabibbo-allowed decay D±→K∓π±π+π0.

The CMS experiment, located at the Large Hadron Collider (LHC) in CERN, has a redundant muon system composed by three different gaseous detector technologies: Cathode Strip Chambers (in the forward regions), Drift Tubes (in the central region), and Resistive Plate Chambers (both its central and forward regions). All three are used for muon reconstruction and triggering. The CMS RPC system confers robustness and redundancy to the muon trigger. The RPC system operation in the challenging background and pileup conditions of the LHC environment is presented. The RPC system provides information to all muon track finders and thus contributing to both muon trigger and reconstruction. The summary of the detector performance results obtained with proton-proton collision at √s = 13 TeV during 2016 and 2017 data taking have been presented. The stability of the system is presented in terms of efficiency and cluster size vs time and increasing instantaneous luminosity. Data-driven predictions about the expected performance during High Luminosity LHC (HL-LHC) stage have been reported.

Abstract A new generation of resistive plate chambers, capable of withstanding high particle fluxes (up to 2000 Hz · cm -2 ) and instrumented with precise timing readout electronics is proposed to equip two of the four high pseudorapidity stations of the CMS muon system. Double-gap RPC detectors, with each gap made of two 1.4 mm High Pressure Laminate electrodes and separated by a gas gap of the same thickness, are proposed. The new layout reduces the amount of the avalanche charge produced by the passage of a charged particle through the detector. This improves the RPC rate capability by reducing the needed time to collect this charge. To keep the RPC efficiency high, a sensitive, low-noise and high time resolution front-end electronics is needed to cope with the lower charge signal of the new RPC. An ASIC called PETIROC that has all these characteristics has been selected to read out the strips of new chambers. Thin (0.6 mm) printed circuit board, 160 cm long, equipped with pickup strips of 0.75 cm average pitch, will be inserted between the two new RPC's gaps. The strips will be read out from both ends, and the arrival time difference of the two ends will be used to determine the hit position along the strip. Results from the improved RPC equipped with the new readout system and exposed to cosmic muons in the high irradiation environment at CERN GIF++ facility are presented in this work.

Using data from Fermilab fixed-target experiment E791, we have measured particle–antiparticle production asymmetries for Λ0, Ξ−, and Ω− hyperons in π−–nucleon interactions at 500 GeV/c. The asymmetries are measured as functions of Feynman-x (xF) and pT2 over the ranges −0.12⩽xF⩽0.12 and 0⩽pT2⩽4 (GeV/c)2. We find substantial asymmetries, even at xF=0. We also observe leading-particle-type asymmetries which qualitatively agree with theoretical predictions.

During Phase-2 of the LHC, known as the High Luminosity LHC (HL-LHC), the accelerator will increase its instantaneous luminosity to 5 × 1034 cm−2 s−1, delivering an integrated luminosity of 3000 fb−1 over 10 years of operation starting from 2027. In view of the HL-LHC, the CMS muon system will be upgraded to sustain efficient muon triggering and reconstruction performance. Resistive Plate Chambers (RPCs) serve as dedicated detectors for muon triggering due to their excellent timing resolution, and will extend the acceptance up to pseudorapidity values of |η|=2.4. Before Long Shutdown 3 (LS3), the RE3/1 and RE4/1 stations of the endcap will be equipped with new improved Resistive Plate Chambers (iRPCs) having different design and geometry than the present RPC system. The iRPC geometry configuration improves the detector's rate capability and its ability to survive the harsh background conditions of the HL-LHC . Also, new electronics with excellent timing performances (time resolution of less than 150 ps) are developed to read out the RPC detectors from both sides of the strips to allow for good spatial resolution along them. The performance of the iRPC has been studied with gamma radiation at the Gamma Irradiation Facility (GIF++) at CERN. Ongoing longevity studies will help to certify the iRPCs for the HL-LHC running period. The main detector parameters such as the current, rate and resistivity are regularly monitored as a function of the integrated charge. Preliminary results of the detector performance will be presented.

Using data from Fermilab fixed-target experiment E769, we have measured particle–antiparticle production asymmetries for Λ0 hyperons in 250 GeV/c π±, K± and p–nucleon interactions. The asymmetries are measured as functions of Feynman-x (xF) and pT2 over the ranges −0.12⩽xF⩽0.12 and 0⩽pT2⩽3 (GeV/c)2 (for positive beam) and −0.12⩽xF⩽0.4 and 0⩽pT2⩽10 (GeV/c)2 (for negative beam). We find substantial asymmetries, even at xF around zero. We also observe leading-particle-type asymmetries. These latter effects are qualitatively as expected from valence-quark content of the target and variety of projectiles studied.

The cross section for backward elastic pd scattering in the proton kinetic energy interval from 0.4 to 1.0 GeV is calculated from a double-triangle diagram with intermediate Δ(1232) excitation. Different approximations for the loop integrals are discussed. The predicted cross sections reproduce quite well the enhancement observed in the experimental data at about 600 MeV.

We propose an explanation for the cross-over problem in Q and Q diffractive productions. We show that it is possible to get a correct cross-over effect in the framework of a dual-reggeized-Deck-model. Unexpected features related to the phases of double-Regge exchange in 2 → 3 reactions are discussed.

Four double-gap CMS resistive plate chambers are being tested at the CERN Gamma Irradiation Facility to determine the performance and aging effects at the expected conditions of the High Luminosity-Large Hadron Collider. Results up to an integrated charge of 290 millicoulomb/cm2 are reported.

Abstract During the upcoming High Luminosity phase of the Large Hadron Collider (HL-LHC), the integrated luminosity of the accelerator will increase to 3000 fb −1 . The expected experimental conditions in that period in terms of background rates, event pileup, and the probable aging of the current detectors present a challenge for all the existing experiments at the LHC, including the Compact Muon Solenoid (CMS) experiment. To ensure a highly performing muon system for this period, several upgrades of the Resistive Plate Chamber (RPC) system of the CMS are currently being implemented. These include the replacement of the readout system for the present system, and the installation of two new RPC stations with improved chamber and front-end electronics designs. The current overall status of this CMS RPC upgrade project is presented.

With the increase of the LHC luminosity foreseen in the coming years, many detectors currently used in the different LHC experiments will be dramatically impacted and some need to be replaced or upgraded. The new ones should be capable to provide time information to reduce the data ambiguity due to the expected high pileup. We propose to equip CMS high |η| muon chambers with pairs of single gap RPC detectors read out by long pickup strips PCB. The precise time measurement (0<15 ps) of the signal induced by particles crossing the detector on both ends of each strip will give an accurate measurement of the position of the incoming particle along the strip. The absolute time measurement, determined by RPC signal (around 1.5 ns) will also reduce the data ambiguity due to the highly expected pileup and help to identify Heavy Stable Charged Particles (HSCP). The development of a specific electronic chain (analog front-end ASIC, time-to-digital converter stage and printed circuit board design) and the corresponding first results on prototype chambers are presented.

The high luminosity expected from the HL-LHC will be a challenge for the CMS detector. The increased rate of particles coming from the collisions and the radioactivity induced in the detector material could cause significant damage and result in a progressive degradation of its performance. Simulation studies are very useful in these scenarios as they allow one to study the radiation environment and the impact on detector performance. Results are presented for CMS RPC stations considering the operating conditions expected at the HL-LHC.

The CMS experiment recorded 177.75 /fb of proton-proton collision data during the RUN-1 and RUN-2 data taking period. Successful data taking at increasing instantaneous luminosities with the evolving detector configuration was a big achievement of the collaboration. The CMS RPC system provided redundant information for the robust muon triggering, reconstruction, and identification. To ensure stable data taking, the CMS RPC collaboration has performed detector operation, calibration, and performance studies. Various software and related tools are developed and maintained accordingly. In this paper, the overall performance of the CMS RPC system and experiences of the data taking during the RUN-2 period are summarised.

Using data from the Fermilab photoproduction experiment E691, we have measured branching ratios for the Cabibbo-suppressed decays D0→¯K0K+π−, D0→K0K−π+, D0→K−K+π−π+, and D0→π+π+π−π−. The data show evidence for several quasi-two-body decays including D0→K*+K− and D0→¯K*0K*0, but not D0→K*−K+. The relative rates of the charged decays indicates that final-state mesons containing virtual-W+-decay quarks are more likely to emerge as vector mesons than are those containing the spectator quarks. The high rate observed for D0→¯K*0K*0 indicates that hadronic final-state interactions play a measurable role in charm decays.Received 26 September 1990DOI:https://doi.org/10.1103/PhysRevD.43.R635©1991 American Physical Society

We measure the neutral D total forward cross section and the differential cross sections as functions of Feynman-x (xF) and transverse momentum squared for 500 GeV/c π−–nucleon interactions. The results are obtained from 88990±460 reconstructed neutral D mesons from Fermilab experiment E791 using the decay channels D0→K−π+ and D0→K−π+π−π+ (and charge conjugates). We extract fit parameters from the differential cross sections and provide the first direct measurement of the turnover point in the xF distribution, 0.0131±0.0038. We measure an absolute D0+D0 (xF>0) cross section of 15.4+1.8−2.3 μbarn/nucleon (assuming a linear A dependence). The differential and total forward cross sections are compared to theoretical predictions and to results of previous experiments.

We show that the cross section of the diffractive production of $b \bar b$ can be described as the sum of two contributions: the first is proportional to the probability of finding a small size $b \bar b$ color dipole in the fast hadron wave function before the interaction with a target, while the second is the $b \bar b$-production after or during the interaction with the target. The formulae are presented as well as the discussion of the interralation between these two contributions and the Ingelman- Schlein and coherent diffraction mechanisms. The main precdition is that the coherent diffraction mechanism dominates at least at the Tevatron Energies, giving the unique possibility to study it experimentally.

We suggest that the present experimental evidence for two Λc+ mass levels may have a deep physical significance and can be taken as the first hint of (cu) and (cd) diquark substructures within the baryon.

During Run-3, the LHC is preparing to deliver instantaneous luminosity in the range from 5 × 1034 cm−2 s−1 to 7.5 × 1034 cm−2 s−1. To ensure stable data taking, providing redundant information for robust muon triggering, reconstruction and identification, the CMS RPC collaboration has used the opportunity given by the LHC long shutdown 2 (LS2), to perform a series of maintenance and preparation activities for the new data taking period. The overall performance of the RPC system after the LS2 commissioning period and the activities in preparation for future data taking will be presented.

During Run2 the high instantaneous luminosity, up to 2.21034cm−2s−1, lead to a substantial hit rate in the Compact Muon Solenoid experiment’s muon chambers due to multiple background sources to physics processes sought for at LHC. In this article we will describe the analysis method devised to measure and identify the contributions to such background in the Resistive Plate Chambers. Thorough understanding of the background rates provides the base for the upgrade of the muon detectors for the High-Luminosity LHC.

Relatar a experiência sobre a organização e realização de palestras sobre o fluxo do processo de Transplante de Medula Óssea (TMO) alogênico em pacientes com doença falciforme da Fundação Hemominas (FH), e compreender os desafios enfrentados pela equipe. O convite para as palestras foi realizado para os profissionais de todas as unidades da FH através do e-mail institucional e grupos de WhatsApp. Foi utilizado um formulário do Google Forms para inscrição dos interessados com informações sobre suas unidades, setores, função e telefone de contato. As palestras foram realizadas por duas médicas hematologistas da Hemominas que atuam também no Hospital das Clínicas da Universidade Federal de Minas Gerais, onde o procedimento de transplante alogênico aparentado é realizado. A atividade aconteceu no auditório do Hemocentro de Belo Horizonte (HBH) com transmissão online por meio da plataforma Google Meet com duração de duas horas. 41 profissionais se inscreveram através do formulário enviado, embora aqueles que não fizeram inscrição antecipadamente também tenham assistido às palestras. Durante a transmissão online foram registrados 25 acessos simultâneos e 19 profissionais participaram de forma presencial, totalizando 44 participantes, de 10 unidades da FH. A proposta de realização de palestras sobre este tema foi feita a partir das dúvidas e inseguranças observadas no cotidiano da equipe que presta assistência ao paciente com doença falciforme. Foi observado grande interesse pelo tema do TMO, o qual contemplou profissionais de diferentes áreas de atuação, como: Assistentes Sociais, Psicólogas, Auxiliares Administrativos, Farmacêuticos, Enfermeiros, Ouvidora, Médicos, Residentes, Pedagogo, Gerente Técnico, Biólogos, Bioquímicos, Técnicos de Enfermagem e Fisioterapeutas. Alguns casos dos pacientes do HBH que passaram pelo procedimento foram abordados, e o relato de um paciente submetido ao transplante recentemente e cuja experiência é considerada exitosa foi apresentado por meio de um vídeo. As perguntas que sugiram foram relacionadas aos casos de rejeição do transplante, outra sobre a desistência de um paciente na fase final do processo, dúvidas sobre os critérios de compatibilidade familiar e tratamentos pós TMO. Levantou-se a necessidade de alinhamento de fluxo do processo em todas as unidades da instituição englobando outros profissionais da equipe, para além dos médicos, como assistentes sociais e psicólogas. O TMO é opção de tratamento curativo para as pessoas com doença falciforme, ofertada pelo SUS desde 2015. Observa-se entre os profissionais de saúde desconhecimento sobre o processo, aliado aos tabus relacionados aos riscos, sugerindo que pacientes que tem indicações e poderiam ser beneficiados com este procedimento, não chegam a ter informações desta modalidade de tratamento. É necessário que a equipe tenha momentos de educação continuada, para disseminar a informação e proporcionar trocas entre os profissionais envolvidos para melhor manejo clínico diante das demandas apresentadas e seja possível avaliar se mais pacientes do Estado de Minas Gerais podem ser submetidos ao TMO.

that would exploit the existing Accumulator and Debuncher rings to generate the required characteristics of the primary proton beam. The proposal requires only modest modifications to the accelerator complex after including those already planned for the NOvA experiment, with which this experiment would be fully compatible. The search for lepton flavor violation (LFV) has long played an important role in the evolution of our understanding of electroweak interactions. The neutrinoless conversion of a muon to an electron in the field of a nucleus is a particularly interesting example of an LFV process involving charged leptons. In the Standard Model, such conversions would take place via loop diagrams involving virtual neutrino mixing, at a rate far below the threshold of any currently conceivable experiment. Indeed, any detectable signal would be a definite indication, albeit indirect, of new dynamics at multi-TeV energy scales. Enhanced rate for this process is an almost universal feature of beyond the Standard Model physics, and the fact that such a process has not been observed has constrained or eliminated many models [1]. While it is widely believed that new physics will appear at LHC energies, the LHC is not well-equipped to study LFV directly. An often-quoted example is in the case of supersymmetry. The LHC will probe slepton masses, but it cannot compete with muon decay experiments in constraining the slepton mixing angles. Sensitive searches for rare or forbidden leptonic and semi-leptonic LFV processes, especially those involving charged leptons, are essential for the comprehensive characterization of new high energy physics. While there are several potential reactions that can be used to probe LFV, muon to electron conversion has the remarkable feature that it does not require the coincidence of two final-state particles. The spectacular signature is a single conversion electron of well-defined energy, separated from most of the sources of background. As a result, very high muon data rates can be handled and an unusually sensitive search for LFV becomes feasible. Indeed, at the level of sensitivity discussed below, a large class of supersymmetric models would predict 100's of conversion events. Additionally, compositeness and Z{prime} models would be probed at the multi-TeV scale in a manner complementary to direct LHC searches. Lepto-quarks would be probed at the 3000 TeV scale. Muon to electron conversion is therefore sensitive to many new physics scenarios at energy scales that cannot be probed by direct searches using other foreseeable accelerators.

We report results from Fermilab experiment E769 on the differential cross sections of D*± charm vector mesons with respect to Feynman-x (xF) and transverse momentum (PT), and on the atomic mass dependence of the production. The D∗ mesons were produced by a 250 GeV π beam on a target of Be, Al, Cu, and W foils. The dσdxF distribution is fit by the form ((1−xF)n) with n=3.5±0.3±0.1, the dσdP2T distribution by exp(−b×P2T) with b=0.70±0.07±0.04 GeV−2, and the cross section A dependence by Aα with α=1.00±0.07±0.02. These results are compared to the equivalent parameters for the production of pseudoscalar D0 and D± charm mesons.Received 10 September 1993DOI:https://doi.org/10.1103/PhysRevD.49.R4317©1994 American Physical Society

Abstract The expected radiation background in the CMS RPC system has been studied using the MC prediction with the CMS FLUKA simulation of the detector and the cavern. The MC geometry used in the analysis describes very accurately the present RPC system but still does not include the complete description of the RPC upgrade region with pseudorapidity 1.9 &lt; |η| &lt; 2.4. Present results will be updated with the final geometry description, once it is available. The radiation background has been studied in terms of expected particle rates, absorbed dose and fluence. Two High Luminosity LHC (HL-LHC) scenarios have been investigated — after collecting 3000 and 4000 fb -1 . Estimations with safety factor of 3 have been considered, as well.

The CMS experiment implements a two-level triggering system composed of Level-1, instrumented by custom-design hardware boards, and a software High Level Trigger. To cope with the more challenging luminosity conditions, a new Level-1 architecture has been deployed during run II. This new architecture exploits in a better way the redundancy and complementarity of the three muon subsystems: Cathode Strip Chambers (CSC), Drift Tubes (DT) and Resistive Plate Chambers (RPC). The role of each subsystem in the Level-1 Muon Trigger is described here, highlighting the contribution from the RPC system. Challenges brought by the HL-LHC environment and new possibilities coming from detector and trigger upgrades are also discussed.

The high pseudorapidity ($\eta$) region of the Compact Muon Solenoid (CMS) muon system is covered by Cathode Strip Chambers only and lacks redundant coverage despite the fact that it is a challenging region for muons in terms of backgrounds and momentum resolution. During the annual Year-End Technical Stops 2022 & 2023, two new layers of improved Resistive Plate Chambers (iRPC) will be added, RE3/1 & RE4/1, which will completely cover the region of $1.8 < |\eta| < 2.4$ in the endcap. Thus, the additional new chambers will lead to increase efficiency for both trigger and offline reconstruction in the difficult region where the background is the highest and the magnetic field is the lowest within the muon system. The extended RPC system will improve the performance and the robustness of the muon trigger. The final design of iRPC chambers and the concept to integrate and install them in the CMS muon system have been finalized. In this report, the main results demonstrating the implementation and installation of the new iRPC detectors in the CMS muon system at high $|\eta|$ region will be presented.

Abstract The present RPC Link System has been servicing as one of the CMS subsystems since installation in 2008. Although the current Link System has been functioning well for the past 13 years, the aging of its electronic components and lack of radiation hard ASICs could present problems for future operations. Additionally, the needs to have a more robust control interface against electromagnetic interference, to improve the trigger performance with finer time granularity and to incorporate a higher bandwidth transmission lines led the idea of upgrading the Link System for the HL-LHC. This paper reviews the features of the recently developed prototype of the new Link System.

The Large Hadron Collider (LHC) at European Organization for Nuclear Research is planned to be upgraded to the high luminosity LHC. Increasing the luminosity makes muon triggering reliable and offline reconstruction very challenging. To enhance the redundancy of the Compact Muon Solenoid (CMS) Muon system and resolve the ambiguity of track reconstruction in the forward region, an improved Resistive Plate Chamber (iRPC) with excellent time resolution will be installed in the Phase-2 CMS upgrade. The iRPC will be equipped with Front-End Electronics (FEE), which can perform high-precision time measurements of signals from both ends of the strip. New Back-End Electronics (BEE) need to be researched and developed to provide sophisticated functionalities such as interacting with FEE with shared links for fast, slow control (SC) and data, in addition to trigger primitives (TPs) generation and data acquisition (DAQ). The BEE prototype uses a homemade hardware board compatible with the MTCA standard, the back-end board (BEB). BEE interacts with FEE via a bidirectional 4.8 Gbps optical paired-link that integrates clock, data, and control information. The clock and fast/slow control commands are distributed from BEB to the FEE via the downlink. The uplink is used for BEB to receive the time information of the iRPC’s fired strips and the responses to the fast/slow control commands. To have a pipelined detector data for cluster finding operation, recover (DeMux) the time relationship of which is changed due to the transmission protocol for the continuous incoming MUXed data from FEE. Then at each bunch crossing (BX), clustering fired strips that satisfy time and spatial constraints to generate TPs. Both incoming raw MUXed detector data and TPs in a time window and latency based on the trigger signal are read out to the DAQ system. Gigabit Ethernet (GbE) of SiTCP and commercial 10-GbE are used as link standards for SC and DAQ, respectively, for the BEB to interact with the server. The joint test results of the BEB with iRPC and Front-End Board (FEB) show a Bit Error Rate of the transmission links less than $$1\times {10^{-16}}$$ , a time resolution of the FEB Time-to-Digital Converter of 16 ps, and the resolution of the time difference between both ends of 160 ps which corresponding a spatial resolution of the iRPC of approximately 1.5 cm. Test results showed the correctness and stable running of the BEB prototype, of which the functionalities fulfill the iRPC requirements.

In the next decades, the Large Hadron Collider (LHC) will run at very high luminosity (HL-LHC) 5×1034 cm−2s−1, factor five more than the nominal LHC luminosity. During this period the CMS RPC system will be subjected to high background rates which could affect the performance by inducing aging effects. A dedicated longevity program to qualify the present RPC system for the HL-LHC running period is ongoing. At the CERN Gamma Irradiation Facility (GIF++) four RPC detectors, from the spare production, are exposed to an intense gamma radiation for a dose equivalent to the one expected at the HL-LHC . The main detector parameters are under monitoring as a function of the integrated charge and the performance is studied with a muon beam. Preliminary results of the study after having collected ≈ 34% of the expected integrated charge will be presented.

The Resistive Plate Chambers (RPC) are used for muon triggers in the CMS experiment. To calibrate the high voltage working-points (WP) and identify degraded detectors due to radiation or chemical damage, a high voltage scan has been performed using 2017 data from pp collisions at a center-of-mass energy of 13 TeV. In this paper, we present the calibration method and the latest results obtained for the 2017 data. A comparison with all scans taken since 2011 is considered to investigate the stability of the detector performance in time.

The second LHC long shutdown period (LS2) is an important opportunity for the CMS Resistive Plate Chambers (RPC) to complete their consolidation and upgrade projects. The consolidation includes detector maintenance for gas tightness, HV (high voltage), LV (low voltage) and slow control operation. All services for the RPC Phase-2 upgrade: improved RPC in stations RE3/1 and RE4/1, were anticipated for installation to LS2. This paper summarises the RPC system maintenance and upgrade activities.

The CMS experiment has 1054 RPCs in its muon system. Monitoring their currents is the first essential step towards maintaining the stability of the CMS RPC detector performance. The current depends on several parameters such as applied voltage, luminosity, environmental conditions, etc. Knowing the influence of these parameters on the RPC current is essential for the correct interpretation of its instabilities as they can be caused either by changes in external conditions or by malfunctioning of the detector in the ideal case. We propose a Machine Learning(ML) based approach to be used for monitoring the CMS RPC currents. The approach is crucial for the development of an automated monitoring system capable of warning for possible hardware problems at a very early stage, which will contribute further to the stable operation of the CMS RPC detector.

The Muon Upgrade Phase II of the Compact Muon Solenoid (CMS) aims to guarantee the optimal conditions of the present system and extend the η coverage to ensure a reliable system for the High Luminosity Large Hadron Collider (HL-LHC) period. The Resistive Plate Chambers (RPCs) system will upgrade the off-detector electronics (called link system) of the chambers currently installed chambers and place improved RPCs (iRPCs) to cover the high pseudo−rapidity region, a challenging region for muon reconstruction in terms of background and momentum resolution. In order to find the best option for the iRPCs, an R&D program for new detectors was performed and real size prototypes have been tested in the Gamma Irradiation Facility (GIF++) at CERN. The results indicated that the technology suitable for the high background conditions is based on High Pressure Laminate (HPL) double-gap RPC. The RPC Upgrade Phase II program is planned to be ready after the Long Shutdown 3 (LS3).

The λ+ c lifetime is calculated in a quark-diquark philosophy using previous results and a number of « natural » assumptions. It is shown that the contribution from the W-exchange dominates in this case that from the W-radiation which is estimated of the order of ∼ 20%. The result is in good agreement with the experimental findings.

We propose a model which is able to explain the main features of the experimental data for the reaction ${\ensuremath{\pi}}^{\ensuremath{-}}p\ensuremath{\rightarrow}\ensuremath{\varphi}\ensuremath{\varphi}n$, starting from the assumption that two glueball resonances with ${J}^{\mathrm{PC}}={2}^{++}$ are produced in this reaction. The couplings of these glueball candidates to $\ensuremath{\varphi}\ensuremath{\varphi}$ are estimated, and come out to be of the same strength as ordinary hadronic couplings.

Abstract As part of the Compact Muon Solenoid experiment Phase-II upgrade program, new resistive plate chambers will be installed in the region at low angle with respect to the beam collision axis, in order to improve the detection of muons with a low transverse momentum. High background conditions are expected in this region during the high-luminosity phase of the Large Hadron Collider, therefore an improved-RPC design has been proposed with a new front-end electronics to sustain a higher particle rate capability and better time resolution. A new technology is used in the front-end electronics resulting in low achievable signal detection of 1–20 fC. Crucial in the design of the improved-RPC is the capability of a two-dimensional readout in order to improve the spatial resolution, mainly motivated by trigger requirements. In this work, the first performance results towards this two-dimensional readout are presented, based on data taken on a real-size prototype chamber with two embedded readout planes with orthogonal strips.

A magnetic spectrometer has been recently installed at the new proton beam facility of the Moscow Meson Factory, to study charged pion production from proton-nucleus interactions at 200–400 MeV bombarding energy. Preliminary reults obtained during the first runs are reported. The planned physics program is also discussed.

Abstract Background The compression of peritumoral healthy tissue in brain tumor patients is considered a major cause of life-threatening neurologic symptoms. This condition is associated with an increase in intracranial pressure. The literature reports that GBM has a mass effect in 72% of autoptic brains of patients who died of brain tumor, with herniation in 50% of all cases. Material and methods We present a preliminary clinical series on 5 cases. The patients are chosen based on criteria of recurrent glioblastoma without the possibility of a gross total resection with a recurrence after STUPP protocol. The surgeries include cytoreduction and augmentative craniotomy. The aim is to increase the intracranial volume and reduce the intracranial pressure in evolving glioblastoma. Clinical and radiological follow-up considers different objective scales and contrast enhancement MRI performed every 3 months. We evaluate KPS, survival rate, complication rate, quality of life using QOL-BN20 and neuropsychological assessment. Results The 12 months of follow-up shows a mean survival rate of 9 months after the surgery. This procedure has no negative impact on the survival rate, complication rate, and quality of life reduction. The neuropsychological evaluation does not show an impact on self-perception of aesthetic appearance. The surgery does not show surgical wound complications. The mean operative time was 225 minutes and was comparable with standard recurrence glioblastoma procedure. Conclusion This work has the main limitation of being preliminary results on small population. However, these results show encouraging outcomes and could be an innovative and salvage therapy for recurrent and incurable glioblastoma. Further follow-up and study must be performed.

We measure the efficiency of CMS Resistive Plate Chamber (RPC) detectors in proton-proton collisions at the centre-of-mass energy of 13 TeV using the tag-and-probe method. A muon from a Z0 boson decay is selected as a probe of efficiency measurement, reconstructed using the CMS inner tracker and the rest of CMS muon systems. The overall efficiency of CMS RPC chambers during the 2016–2017 collision runs is measured to be more than 96% for the nominal RPC chambers.

Several theoretical models inspired by the idea of supersymmetry (SUSY) accommodate the possibility of Heavy Stable Charged Particles (HSCPs). The Phase II upgrade of the CMS-RPC system will allow the trigger and identification of this kind of particles exploiting the Time-of-Flight Technique with the improved time resolution that a new Data Acquisition System (DAQ) system will provide (∼2 ns). Moreover, new Resistive Plate Chambers (RPC) detector chambers will be installed to extend the acceptance coverage up to |η|<2.4 with similar time resolution and better spatial resolution. We present a trigger strategy to detect HSCPs with the RPC detectors. Its performance is studied with Monte Carlo simulations and the expected results with the High Luminosity Large Hadron Collider (HL-LHC) data are shown.

Resistive Plate Chambers have a very important role for muon triggering both in the barrel and in the endcap regions of the CMS experiment at the Large Hadron Collider (LHC) . In order to optimize their performance, it is of primary importance to tune the electronic threshold of the front-end boards reading the signals from these detectors. In this paper we present the results of a study aimed to evaluate the effects on the RPC efficiency, cluster size and detector intrinsic noise rate, of variations of the electronics threshold voltage.

The High Luminosity LHC (HL-LHC) phase is designed to increase by an order of magnitude the amount of data to be collected by the LHC experiments. The foreseen gradual increase of the instantaneous luminosity of up to more than twice its nominal value of $10\times10^{34}\ {\rm cm}^{-1}{\rm s}^{-2}$ during Phase I and Phase II of the LHC running, presents special challenges for the experiments. The region with high pseudo rapidity ($\eta$) region of the forward muon spectrometer ($2.4 > |\eta| > 1.9$) is not equipped with RPC stations. The increase of the expected particles rate up to 2 kHz cm$^{-1}$ ( including a safety factor 3 ) motivates the installation of RPC chambers to guarantee redundancy with the CSC chambers already present. The current CMS RPC technology cannot sustain the expected background level. A new generation of Glass-RPC (GRPC) using low-resistivity glass was proposed to equip the two most far away of the four high $\eta$ muon stations of CMS. In their single-gap version they can stand rates of few kHz cm$^{-1}$. Their time precision of about 1 ns can allow to reduce the noise contribution leading to an improvement of the trigger rate. The proposed design for large size chambers is examined and some preliminary results obtained during beam tests at Gamma Irradiation Facility (GIF++) and Super Proton Synchrotron (SPS) at CERN are shown. They were performed to validate the capability of such detectors to support high irradiation environment with limited consequence on their efficiency.

Taking the Test: Experiences of first-time neuropsychological testtakers in South Africa.Objective: Demand for neuropsychological (NP) testing with culturally/linguistically diverse individuals, including those with limited or no standardized NP testing experience and living in low-and middle-income countries (LMICs), is increasing.Because no research has examined the experience of undergoing NP testing in any population and how it could affect NP test performance, this qualitative study interviewed Xhosaspeaking South Africans about their first experience taking NP tests.Participants and Methods: A guided, semi-structured interview covering the causes of cognitive problems and five domains of the NP testing experience (patterns of abilities, cultural values, familiarity, language, and education) was used.Twenty-two (15 HIV+, 7 HIV-) South Africans (Age M (SD) -33.50 (5.88); % Male-32%) were interviewed.Interviews underwent text review and thematic analysis.Results: Eleven interviewees (50%) thought NP testing was to "check" or "look into" the brain; six (27%) thought it was to assess specific abilities (e.g.memory).Ten (45%) reported feeling nervous due to uncertainty about testing or appearing "dumb".Eleven (50%) and fifteen (68%) described being unbothered by stopping mid-task and not receiving feedback on performance, respectively.Seven (32%) reported performing tasks quickly and accurately to be contradictory.Among causes of cognitive problems, stress (n=5, 23%), excessive worry (n=4, 18%), old age (n=2, 9%), depression (n=1, 5%), and witchcraft (n=1, 5%) were the most commonly reported.Conclusions: There may be limited understanding of the purpose of NP testing, as well as anxiety provoking situations during testing in this sample.Furthermore, there may be limited knowledge of what causes cognitive problems.In LMICs, such as South Africa, neuropsychologists should evaluate an examinee's understanding of NP testing to help foster optimal testing conditions, and may need to provide education on the causes of cognitive problems.

We propose a natural generalization to the case of unequal constituent masses of the formula which gives the correct decay constants for vector mesons of the quarkonium type. Within the philosophy where diquarks are used as baryonic constituents, this allows us to evaluate the decay widths for all vector particles both mesons and diquarks to be used later in the calculation of baryon lifetimes.

We present a new measurement of the mass of the top quark using lepton + jets ttbar events collected by the DO experiment in Run I of the Fermilab Tevatron Collider. The mass is extracted through a comparison of each event with a leading-order matrix element that depends on the top quark mass. The result is M_t=180.1 +/- 3.6 (stat) +/- 3.9 (sys) GeV/c^2. Combining this improved measurement with our previous value from dilepton channels yields the new DO result M_t=179.0 +/- 3.5 (stat) +/- 3.8 (sys) GeV/c^2.

We present a measurement of the cross section for $Z$ production times the branching fraction to $\tau$ leptons, $\sigma \cdot$Br$(Z\to \tau^+ \tau^-)$, in $p \bar p$ collisions at $\sqrt{s}=$1.96 TeV in the channel in which one $\tau$ decays into $\mu \nu_{\mu} \nu_{\tau}$, and the other into $\rm {hadrons} + \nu_{\tau}$ or $e \nu_e \nu_{\tau}$. The data sample corresponds to an integrated luminosity of 226 pb$^{-1}$ collected with the D{\O}detector at the Fermilab Tevatron collider. The final sample contains 2008 candidate events with an estimated background of 55%. From this we obtain $\sigma \cdot$Br$(Z \to \tau^+ \tau^-)=237 \pm 15$(stat)$\pm 18$(sys)$ \pm 15$(lum) pb, in agreement with the standard model prediction.

Neste artigo tentei relacionar os novos desenvolvimentos científicos e as suas consequências para a sociedade como um todo. Isto dentro do quadro do que considero a crise atual do capitalismo e suas possíveis saídas. Além disso, considerei algumas consequências para os trabalhadores em geral, tanto de baixa quanto de alta qualificação universitária. Esse desenvolvimento é visto dentro de uma organização colonial imposta aos países da América Latina, que algumas vezes perdem as possibilidades de exercer suas soberanias.

The purpose of this talk is to show one of the next future experiment in diffractive Physics which will be installed at the DØ experiment at Tevatron/Fermilab for run II, and the importance for Quantum Chromodynamics (QCD) as the theory of the strong interactions. The apparatus that we have developed is the Forward Proton Detector (FPD) to be introduced on the beam line of the Tevatron at both sides of the DØ detector. The FPD is composed by a set of Roman Pots as we will see in the text below.

This paper describes the Forward Proton Detector (FPD) proposed to be implemented in the Dzero Detector, as a set of sub-detectors consisting of 18 Roman Pots. We call attention to the importance of the studies of the diffractive region of the strong interactions.

This paper presents the first measurement of inclusive J/{psi} production cross section in the forward pseudorapidity region 2.5{le}{vert_bar}{eta}thinsp{sup J/{psi}}{vert_bar}{le}3.7 in p{ovr p} collisions at {radical} (s) =1.8 thinspthinspTeV. The results are based on 9.8 pb{sup {minus}1} of data collected using the D0 detector at the Fermilab Tevatron Collider. The inclusive J/{psi} cross section for transverse momenta between 1 and 16 GeV/c is compared with theoretical models of charmonium production. {copyright} {ital 1998} {ital The American Physical Society }

We have made a precise measurement of the central inclusive jet cross section at {radical} (s) =1.8 TeV . The measurement is based on an integrated luminosity of 92 pb{sup {minus}1} collected at the Fermilab Tevatron {ovr p} p Collider with the D0 detector. The cross section, reported as a function of jet transverse energy (E{sub T} {ge} 60 GeV ) in the pseudorapidity interval {vert_bar} {eta} {vert_bar} {le} 0.5, is in good agreement with predictions from next-to-leading order quantum chromodynamics. {copyright} {ital 1999} {ital The American Physical Society}

We report a measurement of the top quark mass using six candidate events for the process p{bar p}{r_arrow}t{bar t}+X{r_arrow}l{sup +}{nu}bl{sup {minus}}{bar {nu}}{bar b}+X, observed in the D0 experiment at the Fermilab p{bar p} collider. Using maximum likelihood fits to the dynamics of the decays, we measure a mass for the top quark of m{sub t}=168.4{plus_minus}12.3(stat){plus_minus}3.6(syst) Gev. We combine this result with our previous measurement in the t{bar t}{r_arrow}l+jets channel to obtain m{sub t}=172.1{plus_minus}7.1 GeV as the best value of the mass of the top quark measured by D0. {copyright} {ital 1999} {ital The American Physical Society}

Limits on the anomalous WW{gamma} and WWZ couplings are presented from a simultaneous fit to the data samples of three gauge boson pair final states in p{bar p} collisions at {radical}(s) =1.8 TeV: W{gamma} production with the W boson decaying to e{nu} or {mu}{nu}, W boson pair production with both of the W bosons decaying to e{nu} or {mu}{nu}, and WW or WZ production with one W boson decaying to e{nu} and the other W boson or the Z boson decaying to two jets. Assuming identical WW{gamma} and WWZ couplings, 95{percent} C.L. limits on the anomalous couplings of {minus}0.30{lt}{Delta}{kappa}{lt}0.43 ({lambda}=0) and {minus}0.20{lt}{lambda}{lt}0.20 ({Delta}{kappa}=0) are obtained using a form factor scale {Lambda}=2.0 TeV. Limits found under other assumptions on the relationship between the WW{gamma} and WWZ couplings are also presented. {copyright} {ital 1998} {ital The American Physical Society}

DO/ has measured the inclusive production cross section of [ital W] and [ital Z] bosons in a sample of 13 pb[sup [minus]1] of data collected at the Fermilab Tevatron. The cross sections, multiplied by their leptonic branching fractions, for production in p[bar p] collisions at [radical] (s) =1.8 TeV are [sigma][sub W] B(W[r arrow]e [nu])=2.36 [plus minus] 0.02 [plus minus] 0.08 [plus minus] 0.13nb, [sigma] [sub W] B(W[r arrow][mu][nu])=2.09 [plus minus] 0.06 [plus minus] 0.22 [plus minus] 0.11nb, [sigma] [sub Z] B(Z[r arrow]e [sup +] e [sup [minus]])=0.218[plus minus] 0.008 [plus minus] 0.008 [plus minus] 0.012nb, and [sigma] [sub Z] B(Z[r arrow][mu] [sup +] [mu] [sup [minus]])=0.178 [plus minus] 0.022 [plus minus] 0.021[plus minus] 0.009nb, where the first uncertainty is statistical and the second systematic; the third reflects the uncertainty in the integrated luminosity. For the combined electron and muon analyses, we find [sigma] [sub W] B(W[r arrow] l [nu])/[sigma] [sub Z] B(Z[r arrow]l [sup +]l [sup [minus]])=10.90 [plus minus] 0.52. Assuming standard model couplings, we use this result to determine the width of the [ital W] boson, and obtain [Gamma] (W)=2.044 [plus minus] 0.097 GeV. [copyright] [ital 1999] [ital The American Physical Society]

Results from a search for new particles decaying to dijets in fi = 1.8 TeV pp collisions using the DO 1992-93 and 1994-95 data samples (104 pb-1) are presented. We exclude at the 95% confidence level the production of excited quarks with masses below 725 GeV/ c2, an additional standard model W boson with masses between 340 and 680 GeV/ c2 and an additional standard model 2 boson with masses between 365 and 615 GeV/c2. *Submitted to the International Europhysics Conference on High Energy Physics, August 19 26, 1997, Jerusalem, Israel.

We present a study of Z{gamma}+X production in p{bar p} collisions at {radical} (s) =1.8TeV from 97 (87)pb{sup {minus}1} of data collected in the ee{gamma} ({mu}{mu}{gamma}) decay channel with the D0 detector at Fermilab. The event yield and kinematic characteristics are consistent with the standard model predictions. We obtain limits on anomalous ZZ{gamma} and Z{gamma}{gamma} couplings for form factor scales {Lambda}=500GeV and {Lambda}=750GeV. Combining this analysis with our previous results yields 95{percent} C.L. limits {vert_bar}h{sub 30}{sup Z}{vert_bar}{lt}0.36, {vert_bar}h{sub 40}{sup Z}{vert_bar}{lt}0.05, {vert_bar}h{sub 30}{sup {gamma}}{vert_bar}{lt}0.37, and {vert_bar}h{sub 40}{sup {gamma}}{vert_bar}{lt}0.05 for a form factor scale {Lambda}=750GeV. {copyright} {ital 1998} {ital The American Physical Society}

We report results of the first search for the pentaquark P{sub {bar c}s} which is predicted to be a doublet of states: P{sup 0}{sub {bar c}s}={vert_bar} {bar c}suud{r_angle} and P{sup {minus}}{sub {bar c}s}={vert_bar} {bar c}sddu{r_angle} . A search was made for the decay P{sup 0}{sub {bar c}s}{r_arrow} {phi}{pi}p in data from Fermilab experiment E791, in which a 500 GeV/c {pi}{sup {minus}} beam interacted with nuclear targets. We present upper limits at 90{percent} confidence level for the ratio of cross section times branching fraction of this decay to that for the decay D{sup {plus_minus}}{sub s}{r_arrow}{phi}{pi}{sup {plus_minus} } . The upper limits vary between 0.022 and 0.046 for M(P{sup 0}{sub {bar c}s} ) between 2.750 and 2.907 GeV/c{sup 2}, assuming a P{sup 0}{sub {bar c}s} lifetime of 0.4 ps. {copyright} {ital 1998} {ital The American Physical Society}

We have searched for first generation scalar leptoquark (LQ) pairs in the e{nu}+jets channel using p{bar p} collider data ({integral}Ldt{approx}115 pb{sup {minus}1}) collected by the D0 experiment at the Fermilab Tevatron during 1992{endash}1996. The analysis yields no candidate events. We combine the results with those from the ee+jets and {nu}{nu}+jets channels to obtain 95{percent} confidence level (C.L.) upper limits on the LQ pair production cross section as a function of mass and of {beta} , the branching fraction to a charged lepton. Comparing with the next-to-leading order theory, we set 95{percent} C.L.lower limits on the LQ mass of 225, 204, and 79 GeV/c{sup 2} for {beta}=1 , (1 )/(2) , and 0, respectively. {copyright} {ital 1998} {ital The American Physical Society}

A search has been carried out for events in the channel p{ovr p}{r_arrow}{gamma}{gamma}+2 jets . Such a signature can characterize the production of a nonstandard Higgs boson together with a W or Z boson. We refer to this nonstandard Higgs, having standard model couplings to vector bosons but no coupling to fermions, as a {open_quotes}bosonic Higgs.{close_quotes} With the requirement of two high transverse energy photons and two jets, the diphoton mass (m{sub {gamma}{gamma}}) distribution is consistent with expected background. A 90 (95){percent} confidence level (C.L.) upper limit on the cross section as a function of mass is calculated, ranging from 0.60 (0.80)thinspthinsppb for m{sub {gamma}{gamma}}=65 GeV/c{sup 2} to 0.26 (0.34)thinspthinsppb for m{sub {gamma}{gamma}}=150 GeV/c{sup 2} , corresponding to a 95{percent} thinspthinspC.L. lower limit on the mass of a bosonic Higgs of 78.5 GeV/c{sup 2} . {copyright} {ital 1999} {ital The American Physical Society}

Using the D0 detector at the 1.8 TeV{ovr p} p Fermilab Tevatron collider, we have measured the inclusive dijet mass spectrum in the central pseudorapidity region {vert_bar} {eta} {sub jet} {vert_bar} {lt}1.0 for dijet masses greater than 200 GeV/c{sup 2} . We have also measured the ratio of spectra {sigma} ({vert_bar} {eta} {sub jet} {vert_bar} {lt} 0.5)/ {sigma} (0.5{lt} {vert_bar} {eta} {sub jet } {vert_bar} {lt}1.0). The order {alpha} {sup 3} {sub s} quantum chromodynamics predictions are in good agreement with the data and we rule out models of quark compositeness with a contact interaction scale {lt} {number_sign} {number_sign}2.4 TeV at the 95{percent} confidence level. {copyright} {ital 1999} {ital The American Physical Society}

We report on a search for charge-1/3 third-generation leptoquarks (LQ) produced in p{bar p} collisions at {radical}(s) =1.8 TeV using the D0 detector at Fermilab. Third-generation leptoquarks are assumed to be produced in pairs and to decay to a tau neutrino and a b quark with branching fraction B. We place upper limits on thinsp{sigma}(p{bar p}{r_arrow}LQ {ovr LQ})B{sup 2} as a function of the leptoquark mass M{sub LQ} . Assuming B=1 , we exclude at the 95{percent} confidence level third-generation scalar leptoquarks with M{sub LQ}{lt}94 GeV/c{sup 2} , and third-generation vector leptoquarks with M{sub LQ}{lt}216 GeV/c{sup 2} (M{sub LQ}{lt}148 GeV/c{sup 2} ) assuming Yang-Mills (anomalous) coupling. {copyright} {ital 1998} {ital The American Physical Society}