A. Sobol

A coupled channel analysis of the centrally produced K+K−and π+π−final states has been performed in pp collisions at an incident beam momentum of 450 GeV/c. The pole positions and branching ratios to ππ and KK of the f0(980), f0(1370), f0(1500) and f0(1710) have been determined. A systematic study of the production properties of all the resonances observed in the π+π−and K+K−channels has been performed.

The reaction pp -> pf (eta eta) ps has been studied at 450 GeV/c. For the first time a partial wave analysis of the centrally produced eta eta system has been performed. Signals for the f0(1500), f0(1710) and f2(2150) are observed and the decay branching fractions of these states are determined.

A study of the f1(1285) and f1(1420) produced in central pp interactions has been performed. For the first time in a single experiment the branching fractions of both mesons in all major decay modes have been determined. Both the f1(1285) and f1(1420) are consistent with being produced by double Pomeron exchange.

The reactions pp→pf(X0)ps, where X0 is observed decaying to π0π0π0π0 , π+π−π+π− and π+π−π0π0 , have been studied at 450 GeV/c. There is evidence for an a2(1320)π decay mode of the η2(1645) and η2(1870) in the π+π−π0π0 and π+π−π+π− final states. The f2(1950) is consistent with being a single resonance with a dominant f2(1270)ππ decay mode. The f0(1370) is found to decay dominantly to ρρ while the f0(1500) is found to decay to ρρ and σσ.

The reaction pp → pf(π+ π− π+ π−)ps has been studied at 450 GeV/c in an experiment designed to search for gl states. A spin analysis has been performed and the dPT filter applied. In addition to the well know f1(1285) there is evidence for two JPC = 2−+ states called the η2(1620) and η2(1875) and a broad scalar called the f0(2000). The production of these states as a function of the dPT kinematical filter shows the behaviour expected for qq states. In contrast, there is evidence for two states at 1.45 GeV and at 1.9 GeV which do not show the behaviour observed for qq states.

A partial wave analysis of the centrally produced K+K− and KS0KS0 channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found in each channel. The striking feature is the observation of peaks in the S-wave corresponding to the f0(1500) and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)a2(1320), the f′2(1525) and the f2(2150) but there is no evidence for a statistically significant contribution in the D-wave in the 1.7 GeV mass region.

A partial wave analysis of the centrally produced π+π− channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300), f0(1500) and fj(1710) with J = 0 in the S-wave. The ϱ(770) is observed dominantly in the P0−-wave and the f2(1270) is observed dominantly in the D0−-wave. In addition, there is evidence for a broad enhancement in the D-wave below 1 GeV.

Results are presented of an analysis of the reactions pp → pf(KS0K±π±)ps and pp → pf(KS0KS0π0)ps at 450 GeV/c. Clear f1(1285) and f1(1420) signals are seen and a spin parity analysis shows that both have IGJPC = 0+1++. The f1(1285) decays to a0(980)π and the f1(1420) decays to K∗K. Both states have a similar dependence as a function of dPT consistent with has been observed for other qq states. Evidence is also presented for a K∗K decay mode of the η2(1620).

A study has been made of pseudoscalar mesons produced centrally in pp interactions. The results show that the eta and etaprime appear to have a similar production mechanism which differs from that of the pi0. The production properties of the eta and etaprime are not consistent with what is expected from double Pomeron exchange. In addition the production mechanism for the eta and etaprime is such that the production cross section are greatest when the azimuthal angle between the pT vectors of the two protons is 90 degrees.

The reaction pp→pfps(K+K−K+K−) in which the K+K−K+K−system is centrally produced has been studied at 450 GeV/c. φφ production has been found to dominate this reaction and is compatible with being produced by double Pomeron exchange. An angular analysis of the φφ system favours JPC=2++ and its dPT dependence is similar to that observed for glueball candidates.

The production and decay properties of the f0(1370), f0(1500), f0(2000) and f2(1950) have been studied in central pp interactions at 450 GeV/c. The dPT, φ and |t| distributions of these resonances are presented. For the J=0 states, the f0(1370) and f0(2000) have similar dPT and φ dependences. These are different to the dPT and φ dependences of the f0(980), f0(1500) and f0(1710). For the J=2 states the f2(1950) has different dependences to the f2(1270) and f2′(1520). This shows that the dPT and φ dependences are not just J phenomena.

A partial wave analysis of the centrally produced π0π0 channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300) and f0(1500) in the the S-wave. and the f2(1270) is observed dominantly in the D0−-wave. In addition, there is evidence for a broad enhancement in the D-wave below 1 GeV.

Exclusive Double Diffractive Events (EDDE) are analysed as the source of information about the central system.Experimental possibilities for exotic particles searches are considered.From the reggeized tensor current picture some azimuthal angle dependences were obtained to fit the data from WA102 experiment and to make predictions for LHC collider.

We propose an experiment at the LHC with leading neutron production.The latter can be used to extract from it the total $\pi^+ p$ cross-sections. With two leading neutrons we can get access to the total $\pi^+\pi^+$ cross-sections. In this note we give some estimates and discuss related problems and prospects.

Evidence is presented that the Pomeron acts as a non-conserved vector current. A study has been made of the azimuthal angle φ, which is defined as the angle between the pT vectors of the two outgoing protons, in the reaction pp→pp(X0) for those resonances (X0) which are compatible with being produced by double Pomeron exchange. These distributions have been compared with a model which describes the Pomeron as a non-conserved vector current and a qualitative agreement is found. In addition, when one of the particles exchanged is known to have spin 0, namely π–Pomeron exchange, the φ distribution is flat.

A partial wave analysis of the centrally produced ηπ0and ηπ−channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. Clear a0(980) and a2(1320) signals have been observed in S and D+ waves respectively. The dPT, φ and |t| distributions of these resonances are presented.

We propose a measurement of leading neutrons spectra at LHC in order to extract inclusive $\pi^+ p$ and $\pi^+\pi^+$ cross-sections with high $p_T$ jets production. The cross-sections for these processes are simulated with the use of parton distributions in hadrons. In this work we estimate the possibility to extract parton distributions in the pion from the data on these cross-sections and also search for signatures of fundamental differences in the pion and proton structure.

A partial wave analysis of the π0π0 system produced centrally in pp collisions at 450 GeV/c shows evidence for the f0(980), f0(1300) and f0(1500) resonances. f2(1270) is observed dominantly in the D0− wave. A broad enhancement is seen in the D-waves below 1 GeV.

We discuss the possibility of measuring leading neutron production at the LHC. These data could be used to extract from it $\pi^+ p$ and $\pi^+\pi^+$ cross-sections. In this note we give some estimates for the case of elastic cross-sections and discuss related problems and prospects.

A study of the reactions pp→pfps(K+K−π+π−) and pp→pfps(K+K−π+π−π0) shows evidence for the K∗(892)K∗(892)and φω channels respectively. The K∗(892)K∗(892)mass spectrum shows a broad distribution with a maximum near threshold and an angular analysis shows that it is compatible with having JP=2+. The behaviour of the cross-section as a function of centre of mass energy, and the four momentum transfer dependence, are compatible with what would be expected if the K∗(892)K∗(892)system was produced via double Pomeron exchange. The dPT behaviour of the φω channel is similar to what has been observed for all the undisputed qq states. In contrast, the dPT behaviour of the K∗(892)K∗(892)final state is similar to what has been observed for the φφ final state and for previously observed glueball candidates.

The reaction pp→pf(ηπ+π−)ps has been studied at 450 GeV/c. There is clear evidence for an a2(1320)π decay mode of the η2(1645) and η2(1870). In addition, there is evidence for an a0(980)π decay mode of both resonances and an f2(1270)η decay mode of the η2(1870). No evidence is found for a JPC=2++a2(1320)π wave.

The reactions pp→pf(X0)ps, where X0 is observed decaying to ηη′ and η′η′, have been studied at 450 GeV/c. This is the first time that these channels have been observed in central production and only the second time that the η′η′ channel has been observed in any production mechanism. In the ηη′ channel there is evidence for the f0(1500) and a peak at 1.95 GeV. The η′η′ channel shows a peak at threshold which is compatible with having JPC=2++ and spin projection JZ=0.

The reaction pp→pf(ωω)ps has been studied at 450 GeV/c and a spin analysis of the ωω channel has been performed for the first time in central production. Evidence is found for the f2(1910) in the JPC=2++ wave with spin projection JZ=2. This is the only state observed in central production with spin projection JZ=2. Its dPT and φ dependencies are similar to those observed for other glueball candidates. In addition, evidence is found for a state with JPC=4++ consistent with the f4(2300). The f0(2000), previously observed in the ρρ final state, is confirmed.

We propose to add forward shower counters, FSC, to CMS along the beam pipes, with 59 m . z . 140 m. These will detect showers from very forward particles with 7 . η . 11 interacting in the beam pipe and surrounding material. They increase the total rapidity coverage of CMS to nearly∆Ω = 4π, thus detecting most of the inelastic cross section σinel, including low mass diffraction. They will help increase our understanding of all high cross section processes, which is important for understanding the “underlying event” backgrounds to most physics searches. To the extent that the luminosity is well known, they may (together with all of CMS) provide the best measurement of σinel at the LHC. They are most useful when the luminosity per bunch crossing is still low enough to provide single (no pileup) collisions. They will allow measurements of single diffraction: p+ p→ p⊕X (where ⊕ means a rapidity gap) for lower masses than otherwise possible, and double diffraction: p + p → X ⊕ X with a large central rapidity gap. They can also be used as rapidity gap detectors for double pomeron exchange and central exclusive processes. Studies of exclusive processes such as γγ → μ+μ− (for luminosity calibration and eventually momentum calibration of forward spectrometers) can be made more cleanly requiring gaps in the FSC counters. Models of forward particle production can be tested indirectly through simulations of hit patterns in the counters. This may reduce the uncertainty on very high energy (E ∼ 10 eV) cosmic ray shower parameters. For heavy ion collisions, the counters act as crude forward calorimeters detecting nuclear fragments (supplementing the ZDC), as well as enabling the study of coherent quasi-elastic scattering e.g. Pb + Pb→ Pb ⊕X⊕ Pb via two-photon interactions. The counters can also be used for real-time monitoring, and if desired for vetoing in the level 1 trigger,both incoming and outgoing beam halo-generated backgrounds (separated by timing) and beam conditions generally. These counters represent a significant enhancement of the beam monitoring, and will make an invaluable contribution to the understanding of the background environment and its topology. They can also provide an additional luminosity monitor, up to luminosities such that the number of interactions per bunch crossing is 〈nX〉 ∼ 5. This note discusses mainly the physics issues; more technical details will be presented in another note. Basically we propose a set of scintillation counters at several locations between 59 m and 140 m along the beam pipes (on both sides), and read out by DAQ electronics identical to that of the HF, with some inputs to the level 1 trigger. Bunch-by-bunch information on rates etc. will be provided for LHC operations. The cost is very modest, given the added value to many physics studies in CMS and to our knowledge of beam conditions generally. a) contact person b) Also at Iowa State University c) Some authors are not members of CMS, but have contributed to this note.

The CMS and TOTEM experiments intend to carry out a joint diffractive/forward physics program with an unprecedented rapidity coverage. The present document outlines some aspects of such a physics program, which spans from the investigation of the low-x structure of the proton to the diffractive production of a SM or MSSM Higgs boson.

We study the possibilities to analyse the data on leading neutrons production at first LHC runs. These data could be used to extract from it π + p and π + π + cross-sections. In this note we estimate relative contributions of π, ρ and a 2 reggeons to charge exchanges and discuss related problems of measurements.

The reaction pp→pf(π+π−π0)ps has been studied at 450 GeV/c in an experiment designed to search for gluonic states. A spin analysis has been performed and the dPT filter applied. The analysis confirms the previous observation that all undisputed qq states are suppressed at small dPT. In addition, a clear difference is observed in the production mechanism for the η and ω.

EDDE is a Monte Carlo event generator, under construction, for different Exclusive Double Diffractive Events. The program is based on the extended Regge-eikonal approach for "soft" processes. Standard Model and its extensions are used for "hard" fusion processes. An interface to PYTHIA, CMSJET and CMKIN is provided.

The reaction pp→pf(π0π0π0)ps has been studied at 450 GeV/c. The π0π0π0 effective mass spectrum shows clear η(547) and π2(1670) signals. Branching ratios for the η(547) and π2(1670) are given as well as upper limits for the decays of the ω(782), a1(1260) and a2(1320) into 3π0.

A study of the centrally produced pp, ppπ0, ppπ+π− and ΛΛ channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. No significant new structures are observed in the mass spectra, however, important new information on the production dynamics is obtained. A systematic study of the production properties of these systems has been performed and it is found that these systems are not produced dominantly by double Pomeron exchange.

The TOTEM collaboration has developed and tested the first prototype of its Roman Pots to be operated in the LHC. TOTEM Roman Pots contain stacks of silicon detectors with strips oriented in two orthogonal directions. To measure proton scattering angles of a few microradians, the detectors will approach the beam centre to a distance of 10σ + 0.5 mm (= 1.3 mm). Dead space near the detector edge is minimised by using two novel "edgeless" detector technologies. The silicon detectors are used both for precise track reconstruction and for triggering. The first full-sized prototypes of both detector technologies as well as their read-out electronics have been developed, built and operated. The tests took place in the proton beam-line of the SPS accelerator ring. In addition, the pot's shielding against electromagnetic interference and the longitudinal beam coupling impedance have been measured with the wire method.

A search for centrally produced charmonium states has been presented. There is no significant evidence for any charmonium production. An upper limit of 2 nb is found for the cross section of χc production using the decay χc(1P)→J/ψγ.

The approach and detectors for diffractive physics based on two current projects—Forward Shower Counter (FSC) and Proton Precision Spectrometer (PPS) are presented.

EDDE is a Monte Carlo event generator for different Exclusive and Semi-Inclusive Double Diffractive processes. The program is based on the extended Regge-eikonal approach for "soft" processes. Standard Model and its extensions are used for "hard" fusion processes.

MonChER is a Monte Carlo event generator for simulation of single and double charge exchange reactions in proton-proton collisions at energies from 0.9 to 14 TeV. Such reactions, $pp\to n+X$ and $pp\to n+X+n$, are characterized by leading neutron production. They are dominated by $π^+$ exchange and could provide us with more information about total and elastic $π^+ p$ and $π^+π^+$ cross sections and parton distributions in pions in the still unexplored kinematical region.

Can we get the information on π p and π π scattering from the LHC data? We present briefly recent results of the IHEP Diffractive Group, which include all the steps: formulation of the problem, an idea how to solve it, experimental tools, Monte‐Carlo simulation and preliminary expectations concerning the first data from the LHC.

A partial wave analysis of the centrally produced + channel has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found. Evidence is found for the f0(980), f0(1300), f0(1500) and fJ(1710) with J = 0 in the the S-wave. The (770) is observed dominantly in the P 0 -wave and the f2(1270) is observed dominantly in the D 0 -wave. In addition, there is evidence for a broad enhancement in the D-wave below 1 GeV.

A strong dependence of meson production with different JPC on the angle between the transverse momentum vectors of the outgoing protons is observed. The φ and t dependences of several resonances with JPC=0±+,1++,2±+ can be described by a model of double Pomeron exchange for the soft Pomerons acting as non-conserved vector currents. The 0++ and 2++ sector reveals asystematic behavior in the data that appears to distinguish between qq̄ and non-qq̄ or glue ball candidates.

A partial wave analysis of the centrally produced 0 and channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. Clear a0(980) and a2(1320) signals have been observed in S and D+ waves respectively. The dPT , and jtj distributions of these resonances are presented.

The reaction pp → pf (π 0 π 0 π 0 )ps has been studied at 450 GeV/c .T heπ 0 π 0 π 0 effective mass spectrum shows clear η(547) and π2(1670) signals. Branching ratios for the η(547) and π2(1670) are given as well as upper limits for the decays of the ω(782), a1(1260) and a2(1320) into 3π 0 .  2001 Published by Elsevier Science B.V.

The reaction pp ! pf( 000 )ps has been studied at 450 GeV/c. The 000 eective mass spectrum shows clear (547) and 2(1670) signals. Branching ratios for the (547) and 2(1670) are given as well as upper limits for the decays of the !(782), a1(1260) and a2(1320) into 3 0 .

The reaction pp! pf ( + 0 )ps has been studied at 450 GeV/c in an experiment designed to search for gluonic states. A spin analysis has been performed and the dPT lter applied. The analysis conrms the previous observation that all undisputed qq states are suppressed at small dPT . In addition, a clear dierence is observed in the production mechanism for the and !.

The reaction $\pi^-p \to \eta\pi^o n$ has been studied with GAMS-2000 spectrometer in the secondary 38 GeV/c $\pi^-$-beam of the IHEP U-70 accelerator. Partial wave analysis of the reaction has been performed in the $\eta\pi^o$ mass range up to 1200 MeV. The $a_0(980)$-meson is seen as a sharp peak in S-wave. The $t$-dependence of $a_0(980)$ production cross section has been studied. Dominant production of the $a_0(980)$ at a small transfer momentum $t$ confirms the hypothesis of Achasov and Shestakov about significant contribution of the $\rho_2$ exchange ($I^GJ^{PC}=1^+2^{--}$) in the mechanism of $a_0(980)$ meson production in $t$-channel of the reaction.

The reaction pp ! pfps(K + K K + K ) in which the K + K K + K system is centrally produced has been studied at 450 GeV/c. production has been found to dominate this reaction and is compatible with being produced by double Pomeron exchange. An angular analysis of the system favours J PC =2 ++ and its dPT dependence is similar to that observed for glueball candidates.

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