Proton-antiproton Collisions Research Articles

NaNu: Proposal for a neutrino experiment at the SPS collider located at the North Area of CERN

Several experiments have been proposed in the recent years to study the nature of tau neutrinos, in particular aiming for a first observation of tau anti-neutrinos as well as new constrains on the strange-quark content of the nucleon. We propose a new low-cost neutrino experiment at the CERN North area, named NaNu (North Area NeUtrino), compatible with the realization of the future SHADOWS and HIKE experiments at the same experimental area.

Results on elastic cross sections in proton–proton collisions at [formula omitted] GeV with the STAR detector at RHIC

We report results on an elastic cross section measurement in proton–proton collisions at a center-of-mass energy s=510 GeV, obtained with the Roman Pot setup of the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). The elastic differential cross section is measured in the four-momentum transfer squared range 0.23≤−t≤0.67 GeV2. This is the only measurement of the proton-proton elastic cross section in this t range for collision energies above the Intersecting Storage Rings (ISR) and below the Large Hadron Collider (LHC) colliders. We find that a constant slope B does not fit the data in the aforementioned t range, and we obtain a much better fit using a second-order polynomial for B(t). This is the first measurement below the LHC energies for which the non-constant behavior B(t) is observed. The t dependence of B is also determined using six subintervals of t in the STAR measured t range, and is in good agreement with the phenomenological models. The measured elastic differential cross section dσ/dt agrees well with the results obtained at s=540 GeV for proton–antiproton collisions by the UA4 experiment. We also determine that the integrated elastic cross section within the STAR t-range is σelfid=462.1±0.9(stat.)±1.1(syst.)±11.6(scale)μb.

Impact of the f-Reggeon exchanges on the observables of the single diffractive dissociation of nucleon at ultrahigh energies

Single diffractive dissociation (SDD) of nucleon in high-energy proton-proton and proton-antiproton collisions is considered in terms of a simple two-Reggeon model with nonlinear Regge trajectories. It is demonstrated that the f-Reggeon impact on the corresponding cross-sections is not negligible up to the LHC energies. As well, it is shown that the account of the f-Reggeon exchanges allows to describe the elastic diffractive scattering (EDS) and SDD of nucleons at ultrahigh energies in the framework of a unified phenomenological scheme. The predictive value of the proposed model is verified.

Determination of the strong-coupling constant from the Z-boson transverse-momentum distribution

The strong-coupling constant is determined from the low-momentum region of the transverse-momentum distribution of Z bosons produced through the Drell–Yan process, using predictions at third order in perturbative QCD. The analysis employs a measurement performed in proton-antiproton collisions at a centre-of-mass energy of s=1.96\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\sqrt{s} = 1.96$$\\end{document} TeV with the CDF experiment. The determined value of the strong coupling at the reference scale corresponding to the Z-boson mass is αS(mZ)=0.1191-0.0016+0.0013\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\alpha _S(m_Z)= 0.1191^{+0.0013}_{-0.0016}$$\\end{document}.

Precision Measurement of the W Mass

Using proton-antiproton collision data corresponding to an integrated luminosity of 8.8 fb-1 collected in Tevatron Run 2, CDF performed a high precision measurement of the W mass. This result, 80433.5±6.4±6.9 MeV, is the most precise so far, and shows a discrepancy of 76 with Standard Model expectations.

Precision measurement of the W boson mass using the full CDF Run II data set

The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. After the observation of the Higgs boson, the last missing component of the model, the measurement of the W boson mass provides a stringent test of the model. A measurement of the W boson mass is presented, which used data corresponding to 8.8 fb−1 of integrated luminosity, collected in proton-antiproton collisions at a 1.96 TeV center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million W boson candidates was used to obtain a Wboson mass of 80433.5±6.4stat ±6.9syst = 80433.5±9.4 MeV, the precision of which exceeds that of all previous measurements combined. This measurement is in significant tension with the standard model expectation.

Quantum information with top quarks in QCD

Top quarks represent unique high-energy systems since their spin correlations can be measured, thus allowing to study fundamental aspects of quantum mechanics with qubits at high-energy colliders. We present here the general framework of the quantum state of a top-antitop (tt¯) quark pair produced through quantum chromodynamics (QCD) in a high-energy collider. We argue that, in general, the total quantum state that can be probed in a collider is given in terms of the production spin density matrix, which necessarily gives rise to a mixed state. We compute the quantum state of a tt¯ pair produced from the most elementary QCD processes, finding the presence of entanglement and CHSH violation in different regions of phase space. We show that any realistic hadronic production of a tt¯ pair is a statistical mixture of these elementary QCD processes. We focus on the experimentally relevant cases of proton-proton and proton-antiproton collisions, performed at the LHC and the Tevatron, analyzing the dependence of the quantum state with the energy of the collisions. We provide experimental observables for entanglement and CHSH-violation signatures. At the LHC, these signatures are given by the measurement of a single observable, which in the case of entanglement represents the violation of a Cauchy-Schwarz inequality. We extend the validity of the quantum tomography protocol for the tt¯ pair proposed in the literature to more general quantum states, and for any production mechanism. Finally, we argue that a CHSH violation measured in a collider is only a weak form of violation of Bell's theorem, necessarily containing a number of loopholes.

High-precision measurement of the W boson mass with the CDF II detector.

The mass of the W boson, a mediator of the weak force between elementary particles, is tightly constrained by the symmetries of the standard model of particle physics. The Higgs boson was the last missing component of the model. After observation of the Higgs boson, a measurement of the W boson mass provides a stringent test of the model. We measure the W boson mass, MW, using data corresponding to 8.8 inverse femtobarns of integrated luminosity collected in proton-antiproton collisions at a 1.96 tera-electron volt center-of-mass energy with the CDF II detector at the Fermilab Tevatron collider. A sample of approximately 4 million W boson candidates is used to obtain [Formula: see text], the precision of which exceeds that of all previous measurements combined (stat, statistical uncertainty; syst, systematic uncertainty; MeV, mega-electron volts; c, speed of light in a vacuum). This measurement is in significant tension with the standard model expectation.

Direct ρL meson production in proton–proton and proton–antiproton collisions

We have investigated the contribution of the Higher Twist (HT) Feynman diagrams to the large-[Formula: see text] inclusive [Formula: see text] meson production cross-section in proton–proton and proton–antiproton collisions and we discuss the phenomenological consequences of possible HT contributions to cross-sections. To extract HT subprocesses from Leading Twist (LT) background, we use various [Formula: see text] meson distribution amplitudes (DAs). In the numerical calculations, the dependencies of the HT contribution on the transverse momentum and the rapidity are discussed with special emphasis on DAs. Analysis of our results shows that HT contributions decrease more rapidly than LT contributions with increasing [Formula: see text]. The preceding results demonstrate that HT contributions must be considered especially in the region of low [Formula: see text] and the HT contribution to the cross-section depends on the choice of the meson DAs.

Charmed baryon pair production in proton-antiproton collisions in effective Lagrangian and Regge approaches

Charmed baryon pair production in proton-antiproton collisions in effective Lagrangian and Regge approaches

Performance Monitoring of the Barrel Time-of-Flight Supermodule for the PANDA Experiment at FAIR

The PANDA experiment at FAIR in Darmstadt will use proton-antiproton collisions, with momenta ranging from 1.5 GeV/c to 15 GeV/c, on a fixed target to study open questions in hadron physics. The Barrel Time-of-Flight detector for this experiment is a scintillating tile hodoscope based on 16 identical and independent subdetectors called Super-Modules arranged in a cylindrical configuration. We have conducted performance studies on one such Super-Module to prove the feasibility of the Barrel Time-of-Flight detector design. Time resolution, signal delay and amplitude drop along the length of the detector were measured and analyzed as a function of the position on the individual scintillator tiles. A time resolution of about 50 ps has been achieved, which is very important for event timing and particle identification.

Measurement of the charge asymmetry of electrons from the decays of W bosons produced in pp¯ collisions at s=1.96 TeV

At the Fermilab Tevatron proton-antiproton (pp¯) collider, high-mass electron-neutrino (eν) pairs are produced predominantly in the process pp¯→W(→eν)+X. The asymmetry of the electron and positron yield as a function of their pseudorapidity constrain the slope of the ratio of the u- to d-quark parton distributions versus the fraction of the proton momentum carried by the quarks. This paper reports on the measurement of the electron-charge asymmetry using the full data set recorded by the Collider Detector at Fermilab in 2001–2011 and corresponding to 9.1 fb−1 of integrated luminosity. The measurement significantly improves the precision of the Tevatron constraints on the parton-distribution functions of the proton. Numerical tables of the measurement are provided.18 MoreReceived 9 July 2021Accepted 29 September 2021DOI:https://doi.org/10.1103/PhysRevD.104.092002Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.Published by the American Physical SocietyPhysics Subject Headings (PhySH)Research AreasHadron-hadron interactionsW & Z bosonsPhysical SystemsElectronsParticles & Fields

A systematic analysis of transverse momentum spectra of J/ψ mesons in high energy collisions

We aggregate the transverse momentum spectra of [Formula: see text] mesons produced in high energy gold–gold (Au–Au), deuteron–gold ([Formula: see text]Au), lead–lead (Pb–Pb), proton–lead ([Formula: see text]–Pb), and proton–(anti)proton ([Formula: see text]–[Formula: see text]) collisions measured by several collaborations at the Relativistic Heavy Ion collider (RHIC), the Tevatron Proton–Antiproton Collider, and the Large Hadron Collider (LHC). The collision energy (the center-of-mass energy) gets involved in a large range from dozens of GeV to 13 TeV (the top LHC energy). We consider two participant or contributor partons, a charm quark and an anti-charm quark, in the production of [Formula: see text]. The probability density of each quark is described by means of the modified Tsallis–Pareto-type function (the TP-like function) while considering that both quarks make suitable contributions to the [Formula: see text] transverse momentum spectrum. Therefore, the convolution of two TP-like functions is applied to represent the [Formula: see text] spectrum. We adopt the mentioned convolution function to fit the experimental data and find out the trends of the power exponent, effective temperature, and of the revised index with changing the centrality, rapidity, and collision energy. Beyond that, we capture the characteristic of [Formula: see text] spectrum, which is of great significance to better understand the production mechanism of [Formula: see text] in high energy collisions.

Observation of Odderon effects at LHC energies: a real extended Bialas\u2013Bzdak model study

The unitarily extended Bialas–Bzdak model of elastic proton–proton scattering is applied, without modifications, to describe the differential cross-section of elastic proton–antiproton collisions in the TeV energy range, and to extrapolate these differential cross-sections to LHC energies. In this model-dependent study we find that the differential cross-sections of elastic proton–proton collision data at 2.76 and 7 TeV energies differ significantly from the differential cross-section of elastic proton–antiproton collisions extrapolated to these energies. The elastic proton–proton differential cross-sections, extrapolated to 1.96 TeV energy with the help of this extended Bialas–Bzdak model do not differ significantly from that of elastic proton–antiproton collisions, within the theoretical errors of the extrapolation. Taken together these results provide a model-dependent, but statistically significant evidence for a crossing-odd component of the elastic scattering amplitude at the at least 7.08 sigma level. From the reconstructed Odderon and Pomeron amplitudes, we determine the sqrt{s} dependence of the corresponding total and differential cross-sections.

Electron lenses: historical overview and outlook

The first electron lenses — understood as “lenses made of electrons” rather than “lenses to focus electrons” — were envisioned in the mid-1990s and built in the early 2000s for compensation of beam-beam effects in the Tevatron proton-antiproton collider. Since then, the lenses — a novel instrument for high-energy particle accelerators — have been added to the toolbox of modern beam facilities, being particularly useful for the energy frontier superconducting hadron colliders (“supercolliders”). In this article we briefly present the history of ideas and developments toward effective use of low-energy high-current bright electron beams in high energy accelerators and discuss the promise of their future applications.

Transversity and heavy quark production on hadron colliders

The azimuthal asymmetry of heavy quarks production on double polarized proton–proton and proton–antiproton colliders are studied in this work at next-to-leading order in alpha _s, with some details included. The purpose is to see whether the effect of extracted transversity distribution functions can be seen on present and near future colliders. All analytic one-loop hard coefficients are given. Numerical results for the asymmetry on proton–(anti)proton colliders are presented.

Diffraction and photon exchange processes at the LHC and parton saturation

We present a review of the recent theoretical and experimental developments related to the field of diffraction, parton saturation, and forward physics. We first discuss our present understanding of the proton structure in terms of quarks and gluons, the degrees of freedom of quantum chromodynamics. We then focus on some of the main results on diffraction at the HERA electron–proton collider in DESY, Germany, at the Tevatron proton–antiproton collider at Fermilab, Batavia, US, and at the CERN Large Hadron Collider (LHC) proton–proton and nucleus–nucleus collider, which is located in Geneva, Switzerland. We also present a selected amount of results on diffraction and photon exchanges that can be done at the LHC experiments and at a future Electron Ion Collider (EIC) to be built in the US at Brookhaven National Laboratory, New York.

Track Reconstruction with PANDA at FAIR

The future PANDA experiment at FAIR aims to investigate a wide range of physics processes in antiproton-proton collisions at rates of up to 20 MHz, while employing a purely software-based event filter. To educate the trigger decisions, a full event reconstruction has to be carried out in real time. This challenge is amplified when considering tracks from particles with long lifetimes and displaced decay vertices, which add to the complexity of the reconstruction algorithms. Here, we present modifications to a cellular automatonbased track finder taking detector time-stamps into account in addition to spatial information, as well as several pattern recognition methods for longitudinal track reconstrucion with PANDA’s Straw Tube Tracker.

Study of pp → 𝚵+ ΛK- with the PANDA Detector

For a deeper insight into the mechanisms of non-perturbative QCD it is essential to understand the excitation pattern of baryons. Up to now only the nucleon excitation spectrum has been subject to systematic experimental studies, while very little is known on excited states of double or triple strange baryons. In studies of antiproton-proton collisions the PANDA experiment is well-suited for a comprehensive baryon spectroscopy program in the multi-strange sector. A large fraction of the inelastic pp cross section is associated to final states with a baryon-antibaryon pair together with additional mesons, giving access to excited states both in the baryon and the antibaryon channel. For final states containing a 𝚵+ 𝚵- pair, cross sections up to µb are expected, corresponding to production rates of ~ 106/d at a luminosity L = 1031 cm-2 s-1. This study focuses on excited 𝚵- states decaying into ΛK-. A strategy to reconstruct the reaction pp → 𝚵+ 𝚵* and its charge conjugate channel with the PANDA detector will be presented.

Simulation study of the reaction with PANDA at FAIR

The PANDA experiment will be one of the pillars of the new Facility for Antiproton and Ion Research (FAIR), which is currently under construction in Darmstadt, Germany. PANDA will be a fixed-target experiment which will allow the study of non-perturbative phenomena of the strong interaction. These will be probed in antiproton-proton collisions in the momentum range of 1.5 - 15 GeV/c. Within the PANDA physics program, strangeness production will be addressed through processes. Measurements of the channel for its comparison with the existing data of the channel are highly encouraged to study the role of isospin symmetry in hadron production dynamics. This work consists on a simulation study focusing on the feasibility of measuring the channel at PANDA.