126196482
ELASTIC SCATTERING OF POSITIVE KAONS ON POLARIZED PROTONS BETWEEN 0.87 AND 2.74 GeV/c. RESULTS AND PHASE-SHIFT ANALYSIS.
Abstract Polarization and differential cross-section data at 16 momenta between 0.86 and 2.74 GeV/ c are presented. (Preliminary data on some of the momenta have been published earlier.) In an energy-independent phase-shift analysis from threshold up to 2.5 GeV/ c , resonant-like as well as non-resonant solutions are found for the P 3 wave. An helicity flip-non-flip decomposition of the partial waves partly supports the indications found in the analyses of other reactions that the pomeron is built up mainly from s -channel helicity non-flip contributions.
120843344
FP420: An R&D proposal to investigate the feasibility of installing proton tagging detectors in the 420-m region at LHC
The physics potential of forward proton tagging in the 420m region at the LHC has only been fully appreciated within the last few years. By detecting protons that have lost less than 1% of their longitudinal momentum, a rich QCD, electroweak, Higgs and BSM program becomes accessible, with the potential to make measurements which are unique at LHC, and difficult even at a future linear collider. By tagging both outgoing protons at 420m in the process pp → p + X + p, the LHC is effectively turned into a glue-glue collider. Initially, this will open up a rich, high-rate diffractive and QCD physics menu, allowing the study of the off-diagonal un-integrated gluon densities of the proton, rapidity gap survival (and therefore underlying event), and providing a source of almost pure gluon jets. In the few-fb-1 luminosity range, a new field of high-energy photon physics opens up, giving access to precision studies of the quartic gauge couplings, anomalous W or Z pair production and, at higher luminosities, supersymmetric particle pair production in an extremely clean environment. As the delivered luminosity reaches 10?s of fb-1, the double-tagged ?central exclusive? production process becomes a tool to search for new physics, delivering signal to background ratios greater than unity for Standard Model (SM) Higgs production, more than an order of magnitude larger for certain supersymmetric (MSSM) scenarios. It can provide a clear determination of the Higgs quantum numbers and excellent mass resolution, which may be necessary to resolve a nearly degenerate Higgs sector. It also offers a unique probe (at least until a linear collider) of the CP structure of the Higgs sector, through azimuthal asymmetry measurements of the tagged protons or detailed analysis of the missing mass lineshape. In addition to Higgs physics, 420m proton tagging provides an opportunity to investigate the entire strong interaction sector of physics within and beyond the Standard Model, from the production of heavy hadron resonances to gluinonia and radions. In pA collisions, the precision study of ultra-peripheral heavy ion collisions will be possible. The 15m drift spaces around 420m from the ATLAS and CMS interaction points offer a physics opportunity that is not exploited in the current LHC physics programme. Protons that lose between 10-3 and 10-2 of their initial momenta emerge from the beams in these regions, which we propose to instrument in the FP420 project. In doing so, we will access a broad range of low-x hard QCD processes, and the central mass range of 115 GeV and upwards which is required for Higgs and discovery physics. This region is at present enclosed in a 'connection cryostat' which maintains a series of superconducting bus-bars, and the beam pipes themselves, at a temperature of 1.7K. A prerequisite for the FP420 project is to assess the feasibility of replacing the 420m interconnection cryostat to facilitate access to the beam pipes and therefore allow proton tagging detectors to be installed. Our intention is to initiate an R&D project based at CERN in collaboration with the UK Cockcroft Institute for Accelerator Science, with the AT/CRI group, the TS/LEA group and with the institutes named on this proposal to provide a feasibility study and conceptual design for the instrumentation of the 420m region. The first opportunity to install such detectors would be the planned LHC shutdown in autumn 2008. Such a physics program cannot be carried out with short runs at high-beta optics, (and consequently low luminosity), but will need the high statistics provided by standard, high luminosity running. The UK groups on this proposal have been awarded 100k pounds of ?seed-corn? money in FY 05 / 06 to support initial design studies. We would like to ask the LHCC to take note of this LOI and its physics goals, and endorse the proposed R&D program.
115609427
VIIth Blois Workshop summary: experimental
The Blois Workshop has become a conference not just restricted to diffractive scattering, but including topics such as searches for SUSY and Higgs, measurements of the top mass and b-decays. I will mention these briefly but will mostly discuss new results (and needed future measurements) in hard diffraction at HERA and the Tevatron.
118601539
Quartz Cherenkov counters for fast timing: QUARTIC
We have developed particle detectors based on fused silica (quartz) Cherenkov radi- ators read out with microchannel plate photomultipliers (MCP-PMTs) or silicon photomultipliers (SiPMs) for high precision timing (st 10-15 ps). One application is to measure the times of small angle protons from exclusive reactions, p+ p! p+ X + p, at the Large Hadron Collider, LHC. They may also be used to measure directional particle fluxes close to external or stored beams. The detectors have small areas (cm 2 ), but need to be active very close ( 4 mm) to the intense LHC beam, and so must be radiation hard and nearly edgeless. We present results of tests of detectors with quartz bars inclined at the Cherenkov angle, and with bars in the form of an "L" (with a 90 corner). We also describe a possible design for a fast timing hodoscope with few mm 2 elements.
120117909
Correlation between the pionization region and the fragmentation region in high energy proton-proton collisions
Abstract Measurements are reported of two-particle correlations in high energy proton-proton collisions with one particle in the pionization region and the other a proton in the fragmentation region. The correlation function is independent of x of the fragmentation proton for 0.55 ⪅ x ⪅ 0.9 and rises at small x . There is an indication that the correlation is an energy-independent function of x . The measurements for two values of the rapidity of the pionization particle give similar results.
121788231
Double Pomeron Exchange from the ISR to the SSC
Abstract After a general introduction to Double Pomeron Exchange I show how the existence of the process was demonstrated at the CERN Intersecting Storage Rings and discuss its value there as a spectroscopic tool in meson/glueball studies. At higher collision energies as now available at the Super Proton Synchrotron and Fermilab p p Colliders it would be very interesting to study hard processes in Double Pomeron Exchange and investigate Pomeron structure. The still higher Large Hadron Collider and Superconducting Super Collider energies extend the range of this physics dramatically, possibly into the electroweak sector.
118388048
Simulating the role of stellar rotation in the spectroscopic effects of differential limb magnification
Finite-source effects of gravitationally microlensed stars have been well discussed in the literature, but the role that stellar rotation plays has been neglected. A differential magnification map applied to a differentially Doppler-shifted surface alters the profiles of absorption lines, compromising their ordinarily symmetric nature. Herein, we assess the degree to which this finite-source effect of differential limb magnification (DLM), in combination with stellar rotation, alters spectroscopically derived stellar properties. To achieve this, we simulated a grid of high-magnification microlensing events using synthetic spectra. Our analysis shows that rotation of the source generates differences in the measured equivalent widths of absorption lines supplementary to DLM alone, but only of the order of a few percent. Using the wings of H alpha from the same simulated data, we confirmed the result of Johnson et al. (2010) that DLM alters measurements of effective temperature by < 100 K for dwarf stars, while showing rotation to bear no additional effect.
3000437
Detection of Rotation in a Binary Microlens: PLANET Photometry of MACHO 97-BLG-41
We analyze PLANET collaboration data for MACHO 97-BLG-41, the only microlensing event observed to date in which the source transits two disjoint caustics. The PLANET data, consisting of 46 V -band and 325 I-band observations from —ve southern observatories, span a period from the initial alert until the end of the event. Our data are incompatible with a static binary lens, but are well —tted by a rotating binary lens of mass ratio q \ 0.34 and angular separation d B 0.5 (in units of the Einstein ring radius), in which the binary separation changes in size by dd \( 0.070 ^ 0.009 and in orientation by during the 35.17 days between the separate caustic transits. We use this measurement, dh \ 5i.61^ 0i.36 combined with other observational constraints, to derive the —rst kinematic estimate of the mass, dis- tance, and period of a binary microlens. The relative probability distributions for these parameters peak at a total lens mass M D 0.3 (M-dwarf binary system), lens distance kpc, and binary period M _ D L D 5.5 P D 1.5 yr. The robustness of our model is demonstrated by its striking agreement with MACHO/ GMAN data that cover several sharp features in the light curve not probed by the PLANET obser- vations, and which did not enter our modeling procedure in any way. Available data sets thus indicate that the light curve of MACHO 97-BLG-41 can be modeled as a source crossing two caustics of a physi- cally realistic rotating binary. Thus, contrary to a recent suggestion, the additional eUects of a postulated planetary companion to the binary lens are not required. Subject headings: binaries: generalgravitational lensingplanetary systems
16941683
Microlensing Constraints on the Frequency of Jupiter-Mass Companions: Analysis of 5 Years of PLANET Photometry
We analyze 5 years of PLANET photometry of microlensing events toward the Galactic bulge to search for the short-duration deviations from single-lens light curves that are indicative of the presence of planetary companions to the primary microlenses. Using strict event-selection criteria, we construct a well-defined sample of 43 intensively monitored events. We search for planetary perturbations in these events over a densely sampled region of parameter space spanning two decades in mass ratio and projected separation, but find no viable planetary candidates. By combining the detection efficiencies of the events, we find that, at 95% confidence, less than 25% of our primary lenses have companions with mass ratio q = 10-2 and separations in the lensing zone, [0.6-1.6]θE, where θE is the Einstein ring radius. Using a model of the mass, velocity, and spatial distribution of bulge lenses, we infer that the majority of our lenses are likely M dwarfs in the Galactic bulge. We conclude that less than 33% of M dwarfs in the Galactic bulge have companions with mass mp = MJ between 1.5 and 4 AU, and less than 45% have companions with mp = 3MJ between 1 and 7 AU, the first significant limits on planetary companions to M dwarfs. We consider the effects of the finite size of the source stars and changing our detection criterion, but find that these do not alter our conclusions substantially.
73625238
1318 new variable stars in a 0.25 square degree region of the Galactic plane
We conducted a deep photometric survey of a 0.5 ◦ × 0.5 ◦ area of the Galactic plane using the WFI instrument on the 2.2-m ESO telescope on La Silla, Chile. The dataset comprises a total of 267 R-band images, 204 from a 16 day observation run in 2005, supplemented by 63 images from a six week period in 2002. Our reduction employed the new numerical kernel difference image analysis method as implemented in the pysis3 code and resulted in more than 500 000 lightcurves of stars down to a magnitude limit of R ∼ 24.5. A search for variable stars resulted in the detection of 1318 variables of different types. 1011 of these are eclipsing or contact binary stars. A number of the contact binaries have low mass-ratios and several of the detached binaries appear to have low-mass components. Three candidate contact binaries have periods at the known cut off including two with periods lower than any previously published. Also identified are 3 possible pre-main sequence detached eclipsing binaries.
16391684
A short, nonplanetary, microlensing anomaly: Observations and light-curve analysis of MACHO 99-BLG-47
We analyze PLANET and MACHO observations of MACHO 99-BLG-47, the first nearly normal microlensing event for which high signal-to-noise ratio data reveal a well-covered, short-duration anomaly. This anomaly occurs near the peak of the event. Short-duration anomalies near the peak of otherwise normal events are expected to arise both from extreme-separation (either very close or very wide), roughly equalmass binary lenses and from planetary systems. We show that the lens of MACHO 99-BLG-47 is in fact an extreme-separation binary, not a planetary system, thus demonstrating for the first time that these two important classes of events can be distinguished in practice. However, we find that the wide-binary and closebinary lens solutions fit the data equally well and cannot be distinguished even at D� 2 ¼ 1. This degeneracy is qualitatively much more severe than the one identified for MACHO 98-SMC-1 because the present degeneracy spans two rather than one dimension in the magnification field and does not require significantly different blending fractions. In the Appendix, we explore this result and show that it is related to the symmetry in the lens equation. Subject headings: binaries: general — gravitational lensing — planetary systems