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Register a new userPomeron Odderon interference in production of pi+ pi- pairs at LHC
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We discuss the production of two pion pairs in photon collisions at high energies as it can take place in ultraperipheral collisions at hadron colliders such as the LHC. We calculate the according matrix elements in kT factorization and discuss the possibility to reveal the existence of the perturbative Odderon by charge asymmetries.
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In this contribution we discuss the production of two pion pairs in high energy photon collisions as they can be produced in ultraperipheral collisions at hadron colliders such as the Tevatron, RHIC or LHC. We find that charge asymmetries may reveal the existence of the perturbative Odderon.
We estimate the production of two meson pairs in high energy photon photon collisions produced in ultraperipheral collisions at LHC. We show that the study of charge asymmetries may reveal the existence of the perturbative Odderon and discuss the concrete event rates expected at the LHC. Sizable rates and asymmetries are expected in the case of proton-proton collisions and medium values of gamma-gamma energies sqrt{s_{gamma gamma}} approx 20GeV. Proton-proton collisions will benefit from a high rate due to a large effective gamma-gamma luminosity and ion-ion collisions with a somewhat lower rate from the possibility to trigger on ultraperipheral collisions and a reduced background from strong interactions.
The transverse single-spin asymmetry A_N observed in high energy proton-proton collisions p^uparrow p to pi X has been found to increase with the momentum fraction x_F of the pion up to the largest measured x_F sim 0.8, where A_N simeq 40%. We consider the possibility that the asymmetry is due to a non-perturbatively generated spin-flip coupling in soft rescattering on the target proton. We demonstrate using perturbation theory that a non-vanishing asymmetry can be generated through interference between exchanges of even and odd charge conjugation provided both helicity flip and non-flip couplings contribute. Pomeron and odderon exchange can thus explain the energy independence of the asymmetry and predicts that the asymmetry should persist in events with large rapidity gaps.
A Regge pole model for Pomeron-Pomeron total cross section in the resonance region $sqrt{M^2}le$ 5 GeV is presented. The cross section is saturated by direct-channel contributions from the Pomeron as well as from two different $f$ trajectories, accompanied by the isolated f$_0(500)$ resonance which dominates the $sqrt{M^{2}}lesssim 1$ GeV region. A slowly varying background is taken into account. The calculated Pomeron-Pomeron total cross section cannot be measured directly, but is an essential part of central diffractive processes. In preparation of future calculations of central resonance production at the hadron level, and corresponding measurements at the LHC, we normalize the Pomeron-Pomeron cross section at large masses $sigma_{t}^{PP} (sqrt{M^2}rightarrow infty) approx$ 1 mb as suggested by QCD-motivated estimates.
A model for Pomeron-Pomeron total cross section in the resonance region $sqrt{M^{2}} le$ 5 GeV is presented. This model is based on Regge poles from the Pomeron and two different $f$ trajectories, and includes the isolated f$_{0}(500)$ resonance in the region $sqrt{M^{2}}lesssim 1$ GeV. A slowly varying background is included. The presented Pomeron-Pomeron cross section is not directly measurable, but is an essential ingredient for calculating exclusive resonance production at the LHC.
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