Resonance Production Cross Section Research Articles

Warped Phenomenology of Higher-Derivative Gravity

We examine the phenomenological implications at colliders for the existence of higher-derivative gravity terms as extensions to the Randall-Sundrum model. Such terms are expected to arise on rather general grounds, e.g., from string theory. In 5-d, if we demand that the theory be unitary and ghost free, these new contributions to the bulk action are uniquely of the Gauss-Bonnet form. We demonstrate that the usual expectations for the production cross section and detailed properties of graviton Kaluza-Klein resonances and TeV-scale black holes can be substantially altered by existence of these additional contributions. It is shown that measurements at future colliders will be highly sensitive to the presence of such terms.

Elusive vector glueball

If the vector glueball exists in the mass range that theory suggests, its resonance production cross section can be seen in e+e- annihilation only if the decay width is very narrow (< a few MeV). Otherwise it willbe observed only indirectly through its mixing with psi(2S). A few tests of the glueball-psi' mixing are proposed for future charm factories.

Two-proton events in the17F(p,2p)16Oreaction

In a recent experimental study (Gomez del Campo et al, PRL 86, 43 (2001)) of the reaction 17F(p,2p)16O, two-proton events were measured from excitations near a 1-, E*=6.15 MeV state in 18Ne. We calculate by means of R-matrix theory the resonant two-proton production cross section and branching ratios. We conclude that it is unlikely that two-proton production via population of the 1- state is sufficient to explain the observed two-proton events. Alternative sources of such events are discussed.

Two-photon mediated resonance production in e+e− collisions: cross sections and density matrices

Earlier described model amplitudes are used in this paper to evaluate both cross sections and density matrices for two-photon mediated resonance production in e + e − collisions. All 25 q q ̄ low-lying 1S 0 , 3P J and 1D 2 resonances can thus be treated. Two independent methods are described to obtain the resonance production density matrices and cross sections. These density matrices combined with a resonance decay density matrix give the detailed angular distributions of the resonance decay products. For two particular decays, χ c2 , χ c1 → γJ/ ψ the details are given. Several numerical results are presented as well.

Study of the diffractive production of baryon states and search for cryptoexotic baryons with hidden strangeness

The reactions of baryon diffractive productionp+N→(pK + K −)+N, p+N→(pϕ)+N, p+N→[Λ(1520)K +]+N p+N→[Σ(1385) o K +]+N in the 70 GeV proton beam were studied. Very sensitive upper limits for the production cross sections of heavy narrow cryptoexotic baryon resonances with hidden strangeness were obtained.

Dual parton model of inelasticpp-interactions and cascade breaking of string

A new cascade model of string breaking with 6 free parameters is constructed. The dual parton model of inelasticpp-collisions, which uses the supposed model of breaking of string, agrees well with the wide set of the experimental data at ISR energies, including the multiplicity, rapidity and transverse momentum distributions, the different correlations and the production cross sections of baryons, antibaryons, strange particles and resonances. For the fitted values of the free parameters, the scaling functions of the model of string breaking are similar to the hadron structure functions. The inability of the dual parton model to explain the rise of the average transverse momentum with multiplicity at the SPS collider energies is discussed.

Cross sections for single-tagged two-photon production of resonances

Simple formulas are given for the production cross section of narrow resonances in single-tagged photon-photon collisions. Production of spin-zero and spin-one states is considered.

Study of the reactions K ±p→K s0π±p at 30 and 50 GeV/ c Description of the apparatus and amplitude analysis of the K s0π system

The reactions K ±p→K s 0 π ±p are studied at 30 and 50 GeV/ c. Data for these reactions were obtained using the Geneva-Lausanne spectrometer whose main characteristics are: (i) large forward acceptance; (ii) high-resolution time-of-flight for recoil proton momentum measurement; (iii) high data-taking rate and on-line pattern recognition. The K ∗(1 −), K ∗(2 +), K ∗(3 −) and K ∗(4 +) resonance parameters and production cross sections are determined. The K π production amplitudes are calculated both as a function of the K π mass and of the momentum transfer. Isoscalar natural parity exchange (NPE) is dominant. The NPE amplitudes are decomposed into pomeron- f-, ω-exchange contributions, and their energy dependence between 10 and 50 GeV/ c is shown to be well-described by a Regge pole model based on the f-dominated pomeron hypothesis.

Inclusive production cross sections of resonances in 32 GeV/ c K +p interactions

The inclusive production of resonances is systematically studied in K +p interactions at 32 GeV/ c. Total production cross sections are given for three baryon resonances, five vector and three 2 + tensor mesons. We also compare the central and fragmentation components of the total production cross sections with quark model predictions.

Partial, total, and resonance production cross sections for the reactionsπ+p→four−prongfinal states at 10.3 GeV/c

The major production channels of four-prong final states resulting from ..pi../sup +/p interacions at a center-of-mass energy of 4.5 GeV are studied. In addition to total production cross sections, comprehensive listings of partial and resonance production cross sections are also given for each final state of interest. All final states, including n..pi../sup +/..pi../sup +/..pi../sup +/..pi../sup -/, are found to exhibit copious resonance production.

Amplitude and natural-parity-exchange analysis of K ±p → (K π) ±p data at 10 GeV/ c

High statistics data for the reactions K ±p → K S 0 π ±p at 10 GeV/ c are analysed. The K ∗(1 −), K ∗(2 +), and K ∗(3 −) resonance parameters and production cross sections are calculated. The Kπ production amplitudes are determined as a function of t and the produced Kπ mass. Isoscalar natural-parity-exchange (NPE) is dominant. The t dependence of the K ± NPE amplitudes have a cross-over at t = −0.3 (GeV/ c) 2 for both K ∗(890) and K ∗(1420) production, being more pronounced for the K ∗(1420). Natural-parity-exchange interference effects are isolated. The NPE amplitudes are decomposed into pomeron-, f-, and ω-exchange contributions. S-wave Kπ production is found to be consistent with the Kπ partial-wave analyses of charge-exchange reactions.

Interference effects from inclusive resonance production

If pions produced at high-energy reactions are decay products of narrow resonances, Bose interference effects at small invariant pion-pion masses are model-independently calculable from (inclusive) resonance production cross sections. We find that the π − π − correlations due to the analogue of the Hanbury Brown-Twiss effect are narrower than those currently observed, the latter being due to more complicated interferences.

Hyperon-initiated reactions at high energies

We present detailed estimates of the differential cross sections for hyperon-nucleon charge-exchange and strangeness-exchange reactions. Polarization and line-reversal systematics are discussed, and reasons for studying such reactions experimentally are explained. In addition, using triple-Regge techniques we estimate the cross sections for inclusive hyperon resonance production, and examine Feynman scaling for these processes.

K ∗ production in K +n → K πN at 8.25 GeV/ c

Reactions K +n → (K π)N have been studied using data from the CERN 2 m deuterium bubble chamber obtained with incident K + of 8.25 GeV/ c. There is an abundant production of K ∗(892) and K ∗(1420). The reaction and K ∗ resonance production cross sections are presented. K ∗ production and decay angular distributions are analyzed. Charge-exchange reactions are dominated by unnatural parity exchange and the non-charge-exchange reaction by natural parity exchange. The K ∗ 0 (892) data are in good agreement with the predictions of an OPE absorption model. A broad enhancement around 1850 MeV could be interpreted as a signal for the K ∗ 0 (1780).

Study of photoproduction on hydrogen in a streamer chamber with tagged photons for 1.6 GeV < Eγ < 6.3 GeV Topological and reaction cross sections

We have studied photoproduction using a 1 m streamer chamber at DESY and a tagged photon beam with an energy range of 1.6 GeV < E γ < 6.3 GeV. We analysed approximately 30 000 events and report topological, channel and resonance production cross sections for a large number of reactions with three and five outgoing charged particles.

Cross-sections for resonance production in $$\bar pn$$ annihilation around 2190 MeV centre-of-mass energyannihilation around 2190 MeV centre-of-mass energy

Cross-sections for resonance production in $$\bar pn$$ annihilation around 2190 MeV centre-of-mass energyannihilation around 2190 MeV centre-of-mass energy

Dual property of diffractive resonances from semilocal factorisation

By semilocal factorisation the ratio of diffractive resonance production cross-sections on π and K should equal the ratio of π and K couplings to P(f) if the resonances are dual to Pomeron (normal meson) exchange. Experimental data favours the former.

Strange-Particle Production byπ+pat 3.7 GeV/c

The results of a study of strange-particle production in ${\ensuremath{\pi}}^{+}p$ interactions at 3.7 GeV/c are presented. Cross sections for a large number of strange-particle final states are given; the over-all strange-particle production cross section is about 1.3 mb. Comparison of cross-section results on two-body and quasi-two-body final states with corresponding ${\ensuremath{\pi}}^{\ensuremath{-}}p$ data shows no evidence for exotic exchanges. Comparison of the peripheral cross sections for ${\ensuremath{\pi}}^{+}p\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\Sigma}}^{+}$ and ${\ensuremath{\pi}}^{+}p\ensuremath{\rightarrow}{K}^{+}{\ensuremath{\Sigma}}^{+}(1385)$ with those for the line-reversed reactions shows reasonable agreement for ${K}^{+}{\ensuremath{\Sigma}}^{+}$ and gross disagreement for ${K}^{+}{\ensuremath{\Sigma}}^{+}(1385)$. Simultaneous ${K}^{*+}(891){\ensuremath{\Sigma}}^{+}(1385)$ production occurs, but, unlike its nonstrange counterpart, it is not dominated by pseudoscalar exchange. There is significant $\ensuremath{\varphi}(1019)$ production via the reaction ${\ensuremath{\pi}}^{+}p\ensuremath{\rightarrow}\ensuremath{\varphi}{\ensuremath{\pi}}^{+}p$, but none of it appears to be associated with ${\ensuremath{\Delta}}^{++}(1236)$. Cross sections for resonance production in various three- and four-body final states are presented.

New relations for two-body reactions from inclusive finite-mass sum rules

Finite-mass sum rule and duality considerations for the inclusive process ab→cX lead to a number of interesting relations amongst the quasi-two-body cross sections ab→cd i , where d i denotes the prominent resonances in the missing-mass channel. The processes π( K )N → NX are studied in detail, and the main results are the following: 1. (i) A superconvergence relation for reggeon (ϱ)-particle (π) scattering gives a sum rule connecting the ϱ-exchange cross sections (d σ /d t ) [ π − p→( gp °, ω , A 2 0 )n]. 2. (ii) Semi local duality considerations in reggeon-particle scattering relate the resonance production cross section ( d σ/ d t) [π( K )N → N d i ] to the resonance mass in terms of the trajectory α ( t ) of the exchangedreggeon. From this the two following corollaries follow: 3. (iii) The ratio of π to (f-ω) exchange contributions increases linearly with the resonance (mass) 2 . 4. (iv) The resonance production cross sections get less peripheral with increasing resonance mass. All the above predictions agree reasonably with the available data on mesonic resonance production.

Dual properties of inclusive spectra

The dual properties of the inclusive reaction π −p → pX are studied over a wide energy range by exploiting the scaling behaviour. Semi-local duality is found to be well satisfied. An energy-dependent triple-Regge analysis reveals a strong triple-pomeron coupling. There is some evidence of an abnormal component in which diffractively produced resonances are dual to pomeron exchange. Combining duality with factorization leads to relations between production cross sections of meson and baryon resonances in πp and pp collisions, which are compatible with existing experimental data.