Exclusive π+π−\pi^+\pi^- Production at the LHC with Forward Proton Tagging

A process of Central Exclusive $\pi^+\pi^-$ production in proton-proton collisions and its theoretical description is presented. A possibility of its measurement, during the special low luminosity LHC runs, with the help of the ATLAS central detector for measuring pions and the ALFA stations for tagging the scattered protons is studied. A visible cross section is estimated to be 21 $\mu$b for $\sqrt{s}=7$ TeV, which gives over 2000 events for 100 $\mu$b$^{-1}$ of integrated luminosity. Differential distributions in pion pseudorapidities, pion and proton transverse momenta as well as $\pi^+\pi^-$ invariant mass are shown and discussed.Comment: 9 pages, 7 figure

Measurement of exclusive production of scalar χc0\chi_{c0} meson in proton-(anti)proton collisions via χc0→π+π−\chi_{c0} \to \pi^{+}\pi^{-} decay

We consider a measurement of exclusive production of scalar $\chi_{c}(0^{++})$ meson in the proton-proton collisions at LHC and RHIC and in the proton-antiproton collisions at the Tevatron via $\chi_{c0} \to \pi^{+}\pi^{-}$ decay. The corresponding amplitude for exclusive double-diffractive $\chi_{c0}$ meson production was obtained within the $k_{t}$-factorization approach including virtualities of active gluons and the corresponding cross section is calculated with unintegrated gluon distribution functions (UGDFs) known from the literature. The four-body $p p \to p p \pi^+ \pi^-$ reaction constitutes an irreducible background to the exclusive $\chi_{c0}$ meson production. We calculate several differential distributions for $pp(\bar{p}) \to pp(\bar{p})\chi_{c0}$ process including absorptive corrections. The influence of kinematical cuts on the signal-to-background ratio is investigated. Corresponding experimental consequences are discussed.Comment: 16 pages, 10 figures, 2 table

pp→ppK+K−pp \to pp K^{+}K^{-} reaction at high energies

We evaluate differential distributions for the four-body $p p \to p p K^{+} K^{-}$ reaction at high energies which constitutes an irreducible background to three-body processes $p p \to p p M$, where $M=\phi$, $f_{2}(1275)$, $f_{0}(1500)$, $f_{2}'(1525)$, $\chi_{c0}$. We consider central diffractive contribution mediated by Pomeron and Reggeon exchanges as well as completely new mechanism of emission of kaons from the proton lines. We include absorption effects due to proton-proton interaction and kaon-kaon rescattering. We compare our results with measured cross sections for the CERN ISR experiment. We make predictions for future experiments at RHIC, Tevatron and LHC. Differential distributions in invariant two-kaon mass, kaon rapidities and transverse momenta of kaons are presented. Two-dimensional distribution in $(y_{K^+}, y_{K^-})$ is particularly interesting. The higher the incident energy, the higher preference for the same-hemisphere emission of kaons. We find that the kaons from the new mechanism of emission directly from proton lines are produced rather forward and backward but the corresponding cross section is rather small. The processes considered here constitute a sizeable contribution to the total proton-proton cross section as well as to kaon inclusive cross section. We consider a measurement of exclusive production of scalar $\chi_{c0}$ meson in the proton-proton collisions via $\chi_{c0} \to K^{+}K^{-}$ decay. The corresponding amplitude for exclusive central diffractive $\chi_{c0}$ meson production is calculated within the $k_{t}$-factorization approach. The influence of kinematical cuts on the signal-to-background ratio is discussed.Comment: 20 pages, 16 figures. text has been corrected and supplemented, cross section for forward/backward mechanisms has been corrected. arXiv admin note: substantial text overlap with arXiv:1103.564

Exclusive production of ω\omega meson in proton-proton collisions at high energies

First we calculate cross section for the $\gamma p \to \omega p$ reaction from the threshold to very large energies. At low energies the pion exchange is the dominant mechanism. At large energies the experimental cross section can be well described within the $k_{t}$-factorization approach by adjusting light-quark constituent mass. Next we calculate differential distributions for the $p p \to p p \omega$ reaction at RHIC, Tevatron and LHC energies for the first time in the literature. We consider photon-pomeron (pomeron-photon), photon-pion (pion-photon) as well as diffractive hadronic bremsstrahlung mechanisms. The latter are included in the meson/reggeon exchange picture with parameters fixed from the known phenomenology. Interesting rapidity distributions are predicted. The hadronic bremsstrahlung contributions dominate at large (forward, backward) rapidities. At small energies the photon-pomeron contribution is negligible compared to the bremsstrahlung contributions. It could be, however, easily identified at large energies at midrapidities. Absorptions effects are included and discussed. Our predictions are ready for verification at RHIC and LHC.Comment: 21 pages, 14 figure

Exclusive pp→nnπ+π+pp \to nn \pi^{+}\pi^{+} reaction at LHC and RHIC

We evaluate differential distributions for the four-body $p p \to n n \pi^+ \pi^+$ reaction. The amplitude for the process is calculated in the Regge approach including many diagrams. We make predictions for possible future experiments at RHIC and LHC energies. Very large cross sections are found which is partially due to interference of a few mechanisms. Presence of several interfering mechanisms precludes extraction of the elastic $\pi^+ \pi^+$ scattering cross section. Absorption effects are estimated. Differential distributions in pseudorapidity, rapidity, invariant two-pion mass, transverse-momentum and energy distributions of neutrons are presented for proton-proton collisions at $\sqrt{s}$ = 500 GeV (RHIC) and $\sqrt{s}$ = 0.9, 2.36 and 7 TeV (LHC). Cross sections with experimental cuts are presented.Comment: 22 pages, 18 figures, calculations have been corrected, new processes added, discussion expanded in print in Phys. Rev.

Low-energy pion-pion scattering in the pp→ppπ+π−pp \to pp\pi^{+}\pi^{-} and ppˉ→ppˉπ+π−p\bar p \to p\bar p\pi^{+}\pi^{-} reactions

We evaluate the contribution of pion-pion rescattering to the $p p \to p p \pi^+ \pi^-$ and $p \bar p \to p \bar p \pi^+ \pi^-$ reactions. We compare our results with the close-to-threshold experimental data. The pion-pion rescattering contribution is found there to be negligible. The predictions for future experiments with PANDA detector at High Energy Storage Ring (HESR) in GSI Darmstadt are presented. It is discussed how to cut off the dominant Roper resonance and double-$\Delta$ excitation mechanisms leading to the $p p \pi^+ \pi^-$ channel in final state. Differential distributions in momentum transfers, transverse momentum, effective two-pions mass, relative azimuthal angle between pions, and pion rapidities are presented.Comment: 14 pages, 11 figure

Feasibility studies of the time-like proton electromagnetic form factor measurements with PANDA at FAIR

The possibility of measuring the proton electromagnetic form factors in the time-like region at FAIR with the \PANDA detector is discussed. Detailed simulations on signal efficiency for the annihilation of $\bar p +p$ into a lepton pair as well as for the most important background channels have been performed. It is shown that precision measurements of the differential cross section of the reaction $\bar p +p \to e^++ e^-$ can be obtained in a wide angular and kinematical range. The individual determination of the moduli of the electric and magnetic proton form factors will be possible up to a value of momentum transfer squared of $q^2\simeq 14$ (GeV/c)$^2$. The total $\bar p +p\to e^++e^-$ cross section will be measured up to $q^2\simeq 28$ (GeV/c)$^2$. The results obtained from simulated events are compared to the existing data. Sensitivity to the two photons exchange mechanism is also investigated.Comment: 12 pages, 4 tables, 8 figures Revised, added details on simulations, 4 tables, 9 figure

Feasibility studies of time-like proton electromagnetic form factors at PANDA at FAIR

Simulation results for future measurements of electromagnetic proton form factors at \PANDA (FAIR) within the PandaRoot software framework are reported. The statistical precision with which the proton form factors can be determined is estimated. The signal channel $\bar p p \to e^+ e^-$ is studied on the basis of two different but consistent procedures. The suppression of the main background channel, $\textit{i.e.}$ $\bar p p \to \pi^+ \pi^-$, is studied. Furthermore, the background versus signal efficiency, statistical and systematical uncertainties on the extracted proton form factors are evaluated using two different procedures. The results are consistent with those of a previous simulation study using an older, simplified framework. However, a slightly better precision is achieved in the PandaRoot study in a large range of momentum transfer, assuming the nominal beam conditions and detector performance

Technical Design Report for the: PANDA Micro Vertex Detector

This document illustrates the technical layout and the expected performance of the Micro Vertex Detector (MVD) of the PANDA experiment. The MVD will detect charged particles as close as possible to the interaction zone. Design criteria and the optimisation process as well as the technical solutions chosen are discussed and the results of this process are subjected to extensive Monte Carlo physics studies. The route towards realisation of the detector is outlined.Comment: 189 pages, 225 figures, 41 table

Feasibility studies for the measurement of time-like proton electromagnetic form factors from p¯ p→ μ+μ- at P ¯ ANDA at FAIR

This paper reports on Monte Carlo simulation results for future measurements of the moduli of time-like proton electromagnetic form factors, | GE| and | GM| , using the p¯ p→ μ+μ- reaction at P ¯ ANDA (FAIR). The electromagnetic form factors are fundamental quantities parameterizing the electric and magnetic structure of hadrons. This work estimates the statistical and total accuracy with which the form factors can be measured at P ¯ ANDA , using an analysis of simulated data within the PandaRoot software framework. The most crucial background channel is p¯ p→ π+π-, due to the very similar behavior of muons and pions in the detector. The suppression factors are evaluated for this and all other relevant background channels at different values of antiproton beam momentum. The signal/background separation is based on a multivariate analysis, using the Boosted Decision Trees method. An expected background subtraction is included in this study, based on realistic angular distributions of the background contribution. Systematic uncertainties are considered and the relative total uncertainties of the form factor measurements are presented