Production Of Meson Resonances Research Articles

Pomeron-Pomeron Scattering

The central exclusive diffractive (CED) production of meson resonances potentially is a factory producing new particles, in particular, a glueball. The produced resonances lie on trajectories with vacuum quantum numbers, essentially on the pomeron trajectory. A tower of resonance recurrences, the production cross-section, and the resonances widths are predicted. A new feature is the form of a non-linear pomeron trajectory, producing resonances (glueballs) with increasing widths. At LHC energies, in the nearly forward direction, the t-channel both in elastic, single, or double diffraction dissociations, as well as in CED, is dominated by the pomeron exchange (the role of secondary trajectories is negligible, however a small contribution from the odderon may be present).

Measurement of meson resonance production in pi ^-+ C interactions at SPS energies

We present measurements of rho ^0, omega and K^{*0} spectra in pi ^{-} + C production interactions at 158 text{ GeV }{/}text{ c } and rho ^0 spectra at 350 text{ GeV }{/}text{ c } using the NA61/SHINE spectrometer at the CERN SPS. Spectra are presented as a function of the Feynman’s variable x_text {F} in the range 0< x_text {F} < 1 and 0< x_text {F} < 0.5 for 158 and 350 text{ GeV }{/}text{ c } respectively. Furthermore, we show comparisons with previous measurements and predictions of several hadronic interaction models. These measurements are essential for a better understanding of hadronic shower development and for improving the modeling of cosmic ray air showers.

Measurements ofWγandZγproduction inppcollisions ats=7 TeVwith the ATLAS detector at the LHC

The integrated and differential fiducial cross sections for the production of a W or Z boson in association with a high-energy photon are measured using pp collisions at sqrt{s} = 7 TeV. The analyses use a data sample with an integrated luminosity of 4.6 fb^{-1} collected by the ATLAS detector during the 2011 LHC data-taking period. Events are selected using leptonic decays of the W and Z bosons (W(e nu,mu nu) and Z(e+ e-, mu+ mu-, nu nubar)) with the requirement of an associated isolated photon. The data are used to test the electroweak sector of the Standard Model and search for evidence for new phenomena. The measurements are used to probe the anomalous WWgamma, ZZgamma and Zgammagamma triple-gauge-boson couplings and to search for the production of vector resonances decaying to Zgamma and Wgamma. No deviations from Standard Model predictions are observed and limits are placed on anomalous triple-gauge-boson couplings and on the production of new vector meson resonances.

Resonances from PHSD

The multi-strange baryon and vector meson resonance production in relativistic nucleus-nucleus collisions is studied within the parton-hadron- string dynamics (PHSD) approach which incorporates explicit partonic degrees- of-freedom in terms of strongly interacting quasiparticles (quarks and gluons) in line with an equation-of-state from lattice QCD as well as the dynamical hadronization and hadronic collision dynamics in the final reaction phase. We find a significant effect of the partonic phase on the production of multi-strange antibaryons at SPS energies due to a slightly enhanced s¯ s pair production from massive time-like gluon decay and a larger formation of antibaryons in the hadronization process. We, futhermore, obtain a visible in-medium effects in the low mass dilepton sector from dynamical vector-meson spectral functions from SIS to SPS energies whereas at RHIC and LHC energies such medium ef- fects become more moderate. In the intermediate mass regime from 1.1 to 3 GeV pronounced traces of the partonic degrees of freedom are found at SPS energies which superseed the hadronic (multi-meson) channels as well as the correlated and uncorrelated semi-leptonic D-meson decays. The dilepton production from the strongly interacting quark-gluon-plasma (sQGP) becomes already visible at top SPS energies and more pronounced at RHIC and LHC energies.

Production of broad baryonic resonances in collisions of heavy nuclei

The problem of the production of short-lived (broad) baryonic resonances in central collisions of relativistic heavy nuclei is considered. It is shown that the available experimental data on this process can be reproduced in the framework of the previously proposed general approach, which describes the production of hadrons in the final state via the coalescence of a proper minimum set of massive dynamical quarks and was successfully applied to the production of long-lived hadrons and short-lived meson resonances. The results can be considered as a prediction of results expected in similar LHC experiments.

MULTIPARTICLE PHASE SHIFT ANALYSIS IN PERIPHERAL PRODUCTION EXPERIMENTS: LESSONS FROM THE PAST

We recall some of our understanding of meson resonance production in high energy collisions from 20 years ago and its implications for a new generation of high statistics experiments. We discuss S-matrix theory, duality and Regge exchanges. We briefly mention some computing issues.

Forty years of antiprotons

The discovery of the antiproton some 40 years ago and the almost synchronous fall of parity $(P)$ and charge conjugation $(C)$ symmetries were soon followed by the realization that $\mathrm{CPT}$ rather than $C$ invariance is the fundamental symmetry connecting matter and antimatter, and that consequently any measurement of the antiproton's properties can be interpreted as a test of that symmetry. It is the latter view of the antiproton, as an object of study in its own right, rather than as a means to such other ends as the production of gauge bosons and meson resonances, that is presented here. The authors review the technical steps that have led from the handful of antiprotons observed by Chamberlain, Segr\`e, Wiegand, and Ypsilantis to the intense, high-quality beams available today and show how the state of rest and isolation required for high precision measurements of their properties can be achieved by confining them in electromagnetic traps or in their microscopic counterparts, exotic atoms. The test bench role of antiprotons and antihydrogen atoms for both $\mathrm{CPT}$ symmetry and the gravitational weak equivalence principle is discussed, and the body of experimental results obtained since 1955 critically reviewed from this standpoint. Future experiments are then discussed in the light of the closure of the CERN Low Energy Antiproton Ring (LEAR), its replacement in 1999 by the Antiproton Decelerator (AD), and the likely antiproton source at the Japan Hadron Facility.

Search for higher twists in meson resonance production in $\pi^-$ N interactions at $p_T \geq 2$ GeV/c

Search for higher twists in meson resonance production in $\pi^-$ N interactions at $p_T \geq 2$ GeV/c

Search for higher twists in meson resonance production in π− N interactions atPT≥2 GeV/c

We study the production of meson resonance atpT≥2 GeV/c inπ− Be interactions at two beam energies (150 and 300 GeV/c). The motivation is to look for the higher twist (HT) production mechanism, expected to exist besides standard hadron production through the fragmentation process of scattered quarks and gluons, the so-called leading twist (LT) mechanism. We show that the φ, K*0 (892) andK*0 (892) are found free from HT effects with a good accuracy, as expected from HT estimates and QCD sum rules. The magnitudes of thef2(1270) andρ0 mesons signals are found larger than expected from the standard Lund (LT) Monte Carlo and from information provided bye+e− annihilation experiments. The possible connection of these excesses with HT physics is discussed. We also report the first evidence for the production off0(975) mesons in hadronic experiments at largepT.

Measurement of inclusive production of light meson resonances in hadronic decays of the Z0

A study of inclusive production of the meson resonances ρ 0, K ∗0 (892), ƒ 0 (975) and ƒ 2 (1270) in hadronic decays of the Z 0 is presented. The measured mean meson multiplicity per hadronic event is 0.83 ± 0.14 for the ρ 0 0.64 ± 0.24 for the K ∗0 (892), 0.10 ± 0.04 for the ƒ 0 (975) in the momentum range p > 0.05 p beam ( x p > 0.05) and 0.11 ± 0.05 for the ƒ 2 (1270) for x p > 0.1 . These values and the corresponding differential cross sections ( 1 σ hadr ) dσ dx p for the vector mesons are in good agreement with the predictions of the JETSET 7.3 PS and HERWIG 5.4 models. The ƒ 2 (1270) production is overestimated by HERWIG but its x p -shape is correctly reproduced. The measured ratios of the production cross sections σ(ƒ 2(1270)) σ(ρ 0) = 0.22 ± 0.08 and σ(ƒ 2(1270)) σ(ƒ 0(975)) = 3 −1 +7 for x p > 0.1 are consistent with the results obtained in hadronic reactions.

Inclusive meson resonance production inK + p interactions at 250 GeV/c

A detailed analysis of the inclusive production of the vector mesonsφ,K*+,0(892)\(\bar K*^0 (892),\rho ^{ + ,0} ,\omega \) and the tensor mesonsK 2 *0 )(1430) andf2(1270) inK+p interactions at 250 GeV/c is presented The data are compared with results at lower energies and with various quark-parton models. The production ofρ0,K*0(892) and\(\bar K*^0 (892)\) increases at the same rate as a function ofs, is concentrated in the central region and is not reproduced by the models. Production of the tensor mesonsf2(1270) andK 2 *0 (1340) is suppressed relative toρ0 andK*0(892) by a factor of about 3.

Production of meson resonances as leading particles in jets in proton-proton collisions at $$\sqrt s = 62$$ GeV at the CERN ISR

The production of ρ(770)0,K *(892)0, $$\bar K^* (892)^0 $$ andf 2(1270) mesons as leading particles in hadron jets (<z>∼0.7) has been measured in deep inelasticpp interactions at the CERN ISR at $$\sqrt s = 62$$ GeV. The comparison of vector and pseudoscalar meson production at the same transverse momentum provides a rather model independent way to determine the fragmentation parameterV/P. We determine(V/P) u,d =1.66±0.18±0.63 from the ρ/π ratio and(V/P) s =0.90±0.13±0.27 from theK */K ratio. For thef 2(1270) production we findf 2/ρ0=0.30±0.08.

InclusiveK *'s and∑ *'s production in 360 GeV/cpp interactions using the European hybrid spectrometer

We have studied the inclusive production of strange meson and baryon resonances in 360 GeV/cpp interactions. Cross sections forK *+(892) andK *−(892) are estimated to be 4.42±0.62 mb and 2.54±0.47 mb respectively and those for∑ +(1385) and∑ −(1385) are 0.67±0.11 mb and 0.26±0.07 mb respectively. Longitudinal and transverse momentum distributions forK *(892) and Σ(1385) are presented, as well as for their decay productsK 0 and Λ. An estimation is given on theK *(1430) and∑ *(1915) productions.

An investigation of narrow meson resonance production in antiproton-proton and antiproton-neutron interactions At 6.1 and 8.9 GeV/ c

An investigation of narrow meson resonance production in antiproton-proton and antiproton-neutron interactions At 6.1 and 8.9 GeV/ c

Inclusive meson resonance production in Kp interactions at 70 GeV

Inclusive meson resonance production in Kp interactions at 70 GeV

Inclusive meson resonance production in K +p interactions at 70 GeV/ c

Inclusive meson resonance production in K +p interactions at 70 GeV/ c

Inclusive production of meson resonances and the sea-quark distributions in the proton

We have extended the application of the recombination model to the production of meson resonances. The x distributions of mesons produced in the pp reactions, including resonances, were found to display certain simple relations, which are independent of specific assumptions about the sea-quark distributions. These predictions can be used both to examine the model and to differentiate between the distributions of strange and nonstrange seaquarks. In the smaller-x region the shapes of meson inclusive distributions sensitivity depend on the sea-quark distribution. Because in the pseudoscalar-meson case, that is just in the same region where contamination from the resonance decay is serious, we use resonance production to determine directly the sea-quark distributions. If we assume that the sea-quark distributions of all three flavors have the same x dependence, with only the normalization of the strange-quark distribution being suppressed, good agreement with the available data can be achieved. And, with the distribution of seaquarks known, the shape of the inclusive distribution for meson production can then be determined without any further adjustable parameters.

Inclusive resonance production in 7.3 GeV/c $$\bar pp$$ interactions

We present results on inclusive baryon and meson resonance production in\(\bar pp\) interactions at 7.3 GeV/c. Total inclusive and semi-inclusive cross sections are given for Δ(1232),∑*(1385), ϱ0,f andK*±(892) production. For the meson resonances separation into annihilation and non-annihilation components has been made, the annihilation component being dominant at this energy. We find that the energy dependence of inclusive cross sections for ϱ0 production inpp interactions and\(\bar pp\) non-annihilations shows a type of scaling behaviour previously reported for ϕ, ψ, ψ′ and ϒ production inpp interactions.Δ++, ϱ0 andK*± production are studied in terms of Feynmanx,y* andpT2. For the vector mesons we compare they* andx dependences with the predictions of simple quark models.

Inclusive production of nonstrange meson resonances in pn interactions at 19 GeV/c

Data on inclusive and semi-inclusive production of nonstrange meson resonances from a bubble chamber study of pn interactions at 19 GeV/c are presented. Most of the results concern ρ0 production. The inclusive cross-sectionσ(pn → ρ0+x)=(2.4±0.4) mb agrees well with pp data. The ρ0 cross-sections are equal in the protonlike and neutron-like hemispheres. The differential cross-sections are in general agreement with earlier observation in pp interactions. In the fragmentation region the approximate structure function can be described byEdσ/dx= =a(1−|x|)n withn=3.0±0.8 in agreement with recent predictions from quark counting rules. The production of ω(780) is observed in the reaction pn→pp+ω+X with a cross-section σ=(0.13±0.03) mb. There is indication of f0(1270) and g(1680) production.

Elastic antiproton-proton photoproduction between threshold and 4.8 GeV

The cross section for the process γ p → p pp has been measured from threshold up to 4.8 GeV using a tagged photon beam and a multiparticle spectrometer which detected all final state particles. The production cross section rises rapidly from threshold to a constant value of 35 nb. No evidence is found in the mass spectra for the production of narrow meson resonances decaying into p p .