Exclusive Central Meson Production in Proton Antiproton Collisions at the Tevatron

Michael Albrow,Maria Zurek,Artur Swiech,A Wrońska,C Guaraldo,H Ströher,R Skibiński,St Kistryn

doi:10.1051/epjconf/20123706011

Michael Albrow, Maria Zurek + Show 6 more

Open Access

https://doi.org/10.1051/epjconf/20123706011

Copy DOI

Abstract

It has been known since the days of the Intersecting Storage Rings, ISR, at CERN, that one can have pp interactions with more than one pomeron, ℙ, exchanged, known as double pomeron exchange. Exclusive hadronic systems, produced by double pomeron exchange, DℙE, have the potential of opening a rich new window on hadron spectroscopy and the diffraction mechanism. We have studied events of the type p + → p + X + where X is a hadron pair (mostly π + π − ) at √s = 900 GeV and 1960 GeV in the Collider Detector at Fermilab (CDF). The hadron pair is central, y ≈ 0, and between two rapidity gaps Δy ≈ 4. The dominant process is double pomeron exchange, DℙE, with restrictions on the quantum numbers of X: Q = S = 0, C = +1, J = 0 or 2. The mass spectra, with about 300K candidate events assumed to be π + π − , shows strong resonant structures attributed to f 0 and f 2 states. We give the ratio of cross sections at √s = 900 GeV and 1960 GeV, and compare with Regge expectations.

Highlights

The pomeron, P, can be defined as the carrier of 4-momentum between protons when they scatter elastically at high energies
In QCD it cannot be a pure state, quark pairs and other gluons must evolve in when Q2, which we can equate with the 4-momentum transfer2 t, becomes large
It is a challenge to theorists to derive Regge theory from QCD, but after 40 years it has not happened

Summary

Introduction

The pomeron, P, can be defined as the carrier of 4-momentum between protons when they scatter elastically at high (i.e. collider) energies It is a strongly interacting color singlet state, at leading order a pair of gluons: P = gg. When Q2 is small ( 2 GeV2) which is usually the case with pomeron exchange, perturbative QCD cannot be used to calculate cross sections, as the coupling αs(Q2) becomes of order 1. Nonperturbative methods, such as Regge theory, are more applicable (see [1],[2] and [3]).

Relevant CDF detectors

Exclusive efficiency

Two exclusive tracks

Statistical uncertainties only