Search

We recall that the exclusive production of high mass objects via γγ fusion at the LHC is not strongly suppressed in comparison with inclusive γγ fusion. Therefore it may be promising to study new objects, X, produced by the γγ subprocess in experiments with exclusive kinematics. We list the main advantages of exclusive experiments. We discuss the special advantage of observing exclusive events.

We discuss the potential to constrain the small-x PDFs using the exclusive production of heavy vector mesons. The calculation of J/φ and γ photoproduction at NLO in collinear factorisation is described. The different behaviour of the NLO corrections for J/φ and → is highlighted and we outline what might be expected from the inclusion of these processes in a PDF fit.

We show that collider data on elastic pp (and p\bar{p}) scattering, including the LHC TOTEM data at 7 TeV, can be well described by a 3-channel eikonal model with only one Pomeron, with parameters that are naturally linked to the perturbative QCD (BFKL) framework. The proton opacity, determined in this way, is then used to account for sizeable absorptive effects. We study the recent measurements of d\sigma/d\Delta\eta made by the ATLAS collaboration, where they select events with large rapidity gaps \Delta\eta. We demonstrate that the absorptive corrections noticeably change both the value and the \Delta\eta dependence of the cross section. We find that our parameter-free calculation is in agreement with these ATLAS data., Comment: 17 pages, 6 figures. Version to be published in EPJC

The predictions of Drell-Yan production of low-mass, lepton-pairs, at high rapidity at the LHC, are known to depend sensitively on the choice of factorization and renormalization scales. We show how this sensitivity can be greatly reduced by fixing the factorization scale of the LO contribution based on the known NLO matrix element, so that observations of this process at the LHC can make direct measurements of parton distribution functions in the low x domain; x less than about 10^{-4}., Comment: 11 pages, 5 figures

The photon detectors based on MPGD (MicroPattern Gaseous Detector) represent the new generation of gaseous photon detectors. We report about an R&D programme dedicated to study both the principles and the engineering aspects of photon detectors based on Thick GEMs (THGEM) electron multipliers coupled to a CsI photoconverting coating. The goal is the development of a gaseous detector of single UV photons, able to stably operate at high gain and high rate, to provide good time resolution and insensitive to magnetic field to be used in the Cherenkov imaging counter RICH-1 of the COMPASS experiment at CERN SPS.

To obtain improved parton densities of the proton, we present a new global analysis of deep inelastic and related data including, in particular, the recent measurements of $F_2$ at HERA, of the asymmetry of the rapidity distributions of $W^\pm$ production at the FNAL $pp$ collider and of the asymmetry in Drell-Yan production in $pp$ and $pn$ collisions. We also incorporate data to determine the flavour dependence of the quark sea distributions. We find that the behaviour of the partons at small $x$ is consistent with the precocious onset of BFKL leading $\log(1/x)$ dynamics. We discuss the ambiguities remaining in the gluon distribution. We present improved predictions for $W$ boson (and $t$ quark) production at the FNAL $\pp$ collider., Comment: preprint DTP/94/34, 26 pages, 21 figures (not included, available on request)

A considerable amount of research into osteoporosis has focused on the management and treatment of bone loss in later life. More recently, a limited amount of research has been directed toward the development of an optimal level of peak bone mass during the adolescent and early adult years. While genetics is a major determinant of bone status, there is considerable evidence that physical activity is an important nonhereditary factor. Studies on adults suggest that the positive effect of physical activity on bone is modest in the short term but may be quite powerful with more intense activity that overloads the muscular system for a longer time period. In children, however, our knowledge about the long-term effects of physical activity on bone accretion is incomplete. This paper presents a review of the pediatric literature dealing with the relationship of physical activity to bone mineral density status in the adolescent population.

We calculate the transverse energy flow accompanying small $x$ deep-inelastic events and compare with recent data obtained at HERA. In the central region between the current jet and the remnants of the proton we find that BFKL leading $\ln(1/x)$ dynamics gives a distinctively large transverse energy distribution, in approximate agreement with recent data., 8 LaTeX pages, 4 figures included as uuencoded postscript at the end of the LaTeX file, Durham preprint DTP/94/30

The distribution of transverse energy [ital E][sub [ital T]], which accompanies deep-inelastic electron-proton scattering at small [ital x], is predicted in the central region away from the current jet and proton remnants. We use BFKL dynamics, which arises from the summation of multiple gluon emissions at small [ital x], to derive an analytic expression for the [ital E][sub [ital T]] flow. One interesting feature is an [ital x][sup [minus][epsilon]] increase of the [ital E][sub [ital T]] distribution with decreasing [ital x], where [epsilon]=(3[alpha][sub [ital s]]/[pi])2 ln2. We perform a numerical study to examine the possibility of using characteristics of the [ital E][sub [ital T]] distribution as a means of identifying BFKL dynamics at DESY HERA.

A muon beam polarimeter has been built for the SMC experiment at the CERN SPS, for muon energies of 100 to 200 GeV. The beam polarisation is determined from the energy spectrum of positrons from the decay μ+ → e+ νcνμ. A polarisation of - 0.82 is measured with a relative systematic accuracy of 3%.

We discuss the characteristic interference phenomena, including real as well as virtual radiative corrections, to the inclusive cross sections for production of heavy unstable systems such as $t\overline{t}$ or ${W}^{+}{W}^{\ensuremath{-}}$ pairs. We demonstrate explicitly the (fortunate) cancellation between emissions associated with the production of unstable particles and with their decays, and between emissions accompanying the decay stages. As a result the total interference effect is shown to be of $O(\frac{{\ensuremath{\alpha}}_{i}\ensuremath{\Gamma}}{M})$ or better (where ${\ensuremath{\alpha}}_{i}=\ensuremath{\alpha} or {\ensuremath{\alpha}}_{s}$ as appropriate).

We study open b\bar{b} production at large rapidity at the LHC in an attempt to pin down the gluon distribution at very low x. For the LHC energy of 7 TeV, at next-to-leading order (NLO), there is a large factorization scale uncertainty. We show that the uncertainty can be greatly reduced if events are selected in which the transverse momenta of the two B-mesons balance each other to some accuracy, that is |\vec p_{1T}+\vec p_{2T}| < k_0. This will fix the scale ��_F \simeq k_0, and will allow the LHCb experiment, in particular, to study the x-behaviour of gluon distribution down to x ~ 10^{-5}, at rather low scales, ��~ 2 GeV. We evaluate the expected cross sections using, for illustrative purposes, various recent sets of Parton Distribution Functions., 13 pages, 5 figures

We discuss the qualitative features of the recent data on multiparticle production observed at the LHC. The tolerable agreement with Monte Carlos based on LO DGLAP evolution indicates that there is no qualitative difference between `hard' and `soft' interactions; and that a perturbative QCD approach may be extended into the soft domain. However, in order to describe the data, these Monte Carlos need an additional infrared cutoff k_min with a value k_min ~ 2-3 GeV which is not small, and which increases with collider energy. Here we explain the physical origin of the large k_min. Using an alternative model which matches the `soft' high-energy hadron interactions smoothly on to perturbative QCD at small x, we demonstrate that this effective cutoff k_min is actually due to the strong absorption of low k_t partons. The model embodies the main features of the BFKL approach, including the diffusion in transverse momenta, lnk_t, and an intercept consistent with resummed next-to-leading log corrections. Moreover, the model uses a two-channel eikonal framework, and includes the contributions from the multi-Pomeron exchange diagrams, both non-enhanced and enhanced. The values of a small number of physically-motivated parameters are chosen to reproduce the available total, elastic and proton dissociation cross section (pre-LHC) data. Predictions are made for the LHC, and the relevance to ultra-high-energy cosmic rays is briefly discussed. The low x inclusive integrated gluon PDF, and the diffractive gluon PDF, are calculated in this framework, using the parameters which describe the high-energy pp and p\bar{p} `soft' data. Comparison with the PDFs obtained from the global parton analyses of deep inelastic and related `hard' scattering data, and from diffractive deep inelastic data looks encouraging., 36 pages, 12 figures. Version published in EPJC which has captions to Figs. 8 and 9 corrected

We briefly review the Standard Model prediction of g−2 and confront it with the formidably accurate measurement from BNL. The focus is on recent improvements of the hadronic vacuum polarisation contributions. We also calculate the running QED coupling at the scale of the Z boson mass, α(MZ2), an important ingredient in electroweak precision fits.

The structure functions for deep-inelastic electron-proton scattering at small x are calculated using the QCD kT-factorization theorem together with the gluon distribution obtained from solving the Lipatov (or BFKL) equation. We study the theoretical uncertainties in the predictions and show, in the HERA regime, that the effective slope λ, defined by [Formula: see text], is a remarkably stable prediction of perturbative QCD, where [Formula: see text], is suitably defined background. We propose a procedure for identifying the Lipatov effect from small x measurements of F2. We apply it to the recent HERA data, and hence determine λ.

The authors review the present knowledge of the partonic structure of the proton. They compare and contrast the parton distributions obtained recently by the MRS and CTEQ collaborations in global analyses of deep-inelastic and related data, including the new NMC and CCFR structure function measurements. They discuss the information that is at present available on the flavour asymmetry of the sea-quark distributions of the proton and, in particular, describe how well experiments can discriminate between u, d and s. They comment on extrapolations into the small-x region that is accessible at HERA.

We study the possible flavour asymmetry, $\bar{u} \neq \bar{d}$, of the light quark sea distributions of the proton. We discuss the information that is at present available from data on deep-inelastic lepton-nucleon scattering and from Drell-Yan production on various nuclear targets. We show that the ratio of dilepton yields on hydrogen and deuterium targets is very sensitive to $\bar{u}-\bar{d}$., Comment: LaTeX, 8 text pages, 4 figures (not included)

We study the effects of radiative corrections and W boson finite width effects on the energy dependence of the process e + e − → W + W − → f 1 f 2 f 3 f 4 in the W+W− threshold region. We pay particular attention to the effect of the W finite width on the Coulomb correction. We present a “master” formula for the cross section which is relevant to a precision determination of MW by an energy scan of W+W− production through the threshold region.

We refine our recent determination of parton distributions with the inclusion of the new published sets of precise muon and neutrino deep inelastic data. Deuteron screening effects are incorporated. The t t cross section at the FNAL p p collider is calculated.

Perturbative QCD is used to predict the deep-inelastic electron-proton structure functions [ital F][sub [ital T],][ital L]([ital x],[ital Q][sup 2]) in the small [ital x] region ([ital x][similar to]10[sup [minus]3]) from an experimental knowledge of the behavior at larger [ital x]. Shadowing corrections are quantified.

The measurement of the polarisation of the τ from the energy distributions of its decay products is studied for the various decay channels: τ → πν, ϱν, a1ν, lνν, and, in particular, the model dependence of the description of the τ → (3π)ν decay is examined. It is shown how this information may be used to identify charged and neutral Higgs bosons via H± → τ±ν and H0 → τ−τ+ decay channels. The effect of using various decay distributions and their correlations in the τ polarisation measurements in Z → τ−τ+ is studied quantitatively. We show that a significant improvement is achieved even if ϱ± → τ±τ0 cannot be distinguished from a1 → τ±τ0τ0. Also τ polarisation measurements from the decays of possible new W or Z bosons at hadron colliders are discussed.

We report on the first measurement of the spin-dependent structure function g1d of the deuteron in the deep inelastic scattering of polarised muons off polarised deuterons, in the kinematical range 0.006222. The first moment, Γ1d=sh{phonetic}01 g1d dx=0.023±0.020 (stat.) ± 0.015 (syst.), is smaller than the prediction of the Ellis-Jaffe sum rules. Using earlier measurements of g1p, we infer the first moment of the spin-dependent neutron structure function g1n. The difference Γ1p-Γ1n=0.20 ±0.05 (stat.) ± 0.04 (syst.) agrees with the prediction of the Bjorken sum rule, Γ1p-Γ1n=0.191 ±0.002.

The recent publication of the first validated equation for the estimation of muscle mass (MM) in men has made possible a comparison of MM in athletes from different sports. Limb girths and skinfold thicknesses were measured in 62 male athletes (aged 17-38 years) and 13 non-athletic males (aged 22-36 years). The MM (g) was calculated from the equation MM = S(0.0553 Gt2 + 0.0987 Gf2 + 0.0331 Gc2)-2445, where S is stature, Gt is the mid-thigh girth corrected for the front thigh skinfold thickness, Gc is the maximum calf girth corrected for the calf skinfold thickness and Gf is the uncorrected maximum forearm girth (all in cm). The athletes were classified as gymnasts (n = 10), basketball players (n = 10), body-builders (n = 10), track and field power athletes (n = 12), track and field long sprinters (n = 10) or distance runners (n = 10). The MM means ranged from 38.4 kg for the distance runners to 58.7 kg for the body-builders. Both body-builders and basketball players had significantly greater MM than gymnasts, long sprinters, non-athletic males and distance runners (P < 0.01). Also, MM was greater in track and field power athletes than in distance runners (P < 0.05). The MM as a percentage of body mass (%MM) ranged from 56.5% in the non-athletic group to 65.1% in the body-builders; body-builders scored higher than basketball players (P < 0.05), distance runners (P < 0.01) and the non-athletic group (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

New data on structure functions from deep-inelastic scattering provide new information on parton distributions, particularly in the $0.01lxl0.1$ interval. This has important implications for predictions for the DESY $\mathrm{ep}$ collider HERA and for present and future high-energy hadron colliders. We present the results of updated fits to all available precision structure function and related data. We focus in particular on two issues: (a) the increase in the sea-quark distributions at small $x$ implied by new ${F}_{2}$ data from the New Muon Collaboration, and its implications for other processes, and (b) the evidence for SU(2)-symmetry breaking in the light-quark sea. We show that although good fits can be obtained with or without this symmetry breaking, more physically reasonable parton distributions are obtained if we allow $\overline{d}g\overline{u}$ at small $x$. With the inclusion of the latest deep-inelastic data we find ${\ensuremath{\alpha}}_{s}({M}_{Z})={0.111}_{\ensuremath{-}0.005}^{+0.004}$. We also show how $W$, $Z$, and Drell-Yan production at $\overline{p}p$ colliders can give information on parton distributions.

The signature at the LHC of many Beyond the Standard Model (BSM) scenarios is events with large missing energy. If the forward outgoing protons are measured, we show that the production and decay of BSM particles in the central rapidity interval, with gaps in rapidity either side, offers certain advantages over inclusive production, to search for signals (a) with missing longitudinal 4-momentum (typical of invisible Higgs production), and (b) for new light pseudoscalar bosons., 15 pages, 3 figures

The value of the important triple-Pomeron coupling is estimated by an unorthodox procedure using the known diffractive parton distribution functions. The result is g_{3P}\simeq 0.2g_N, where g_N is the Pomeron-nucleon coupling. This is in excellent agreement with an independent determination, g_{3P}\simeq 0.2g_N, previously obtained by analysing the available data in the triple-Regge region with absorptive effects taken into account., Comment: 7 pages, 5 figures

The state of the art concerning transverse-spin and transverse-momentum phenomena in hard hadronic reactions is reviewed. An account is given of single-spin and azimuthal asymmetries in semiinclusive deep inelastic scattering, e^+ e^- annihilation, Drell-Yan production, and hadroproduction. The ongoing experiments and the main theoretical frameworks are described in the first part of the paper. The second part is devoted to the experimental findings and their phenomenological interpretations. A brief discussion of the perspectives of future measurements is finally presented., 95 pages

We study the sensitivity of our recent MSTW 2008 NLO and NNLO PDF analyses to the values of the charm- and bottom-quark masses, and we provide additional public PDF sets for a wide range of these heavy-quark masses. We quantify the impact of varying m_c and m_b on the cross sections for W, Z and Higgs production at the Tevatron and the LHC. We generate 3- and 4-flavour versions of the (5-flavour) MSTW 2008 PDFs by evolving the input PDFs and alpha_S determined from fits in the 5-flavour scheme, including the eigenvector PDF sets necessary for calculation of PDF uncertainties. As an example of their use, we study the difference in the Z total cross sections at the Tevatron and LHC in the 4- and 5-flavour schemes. Significant differences are found, illustrating the need to resum large logarithms in Q^2/m_b^2 by using the 5-flavour scheme. The 4-flavour scheme is still necessary, however, if cuts are imposed on associated (massive) b-quarks, as is the case for the experimental measurement of Z b bbar production and similar processes., Comment: 40 pages, 11 figures. Grids can be found at http://projects.hepforge.org/mstwpdf/ and in LHAPDF V5.8.4. v2: version published in EPJC

We present a method for numerical modeling of binary homogeneous random fields based on thresholds of Gaussian functions. The method enables us to reproduce the average value and correlation function of the observed binary field. The method is comparatively simple, and on several examples we demonstrate that it can be effective for simulation of a wide class of binary random fields.

We discuss whether deep-inelastic events containing a measured jet at HERA will be able to identify the x−Λ behaviour at small x which is predicted by perturbative QCD via the Lipatov equation.

Recent measurements of the structure functions for deep inelastic scattering made by the NMC and the CCFR collaboration provide new information on parton distributions, particularly in the 0.01 < x < 0.1 interval. We describe (next-to-leading order) determinations of parton distributions whih incorporate these new data together with other deep-inelastic and related data, and which allow the possibility of flavour dependence of the light quark sea (i.e. u ≠ d) as implied by the Gottfried sum rule. We discuss extrapolations to small x.

We examine the feasibility of using deep-inelastic events containing a measured jet to identify the x−λ singular type of behaviour at small x, which is predicted by perturbative QCD via the Lipatov equation. We calculate the cross sections at HERA for relevant choices of the deep-inelastic and jet kinematic variables and we indicate the signature of the x−λ behaviour.

There are few studies of the effect of smoking on bone density in young women. The reported antiestrogenic effect of smoking could be a mechanism for a possible effect of smoking on bone. We measured bone mineral density (BMD) by dual-energy X-ray absorptiometry (whole body, proximal femur, lumbar spine), and serum levels (mid-follicular phase) of testosterone (T), estradiol (E2), sex hormone-binding globulin (SHBG), and cortisol in 52 women (25 smokers, 27 nonsmokers) aged 20-35 years. The two groups did not differ significantly in age, height, weight, or the sum of eight skinfold thicknesses. The mean number of cigarettes smoked per day and the number of years of smoking were 16.9 and 12.9, respectively. There were no significant differences in BMD between smokers and nonsmokers at any site. For both smokers and nonsmokers, SHBG and the free androgen index (T/SHBG) made significant contributions (P less than 0.005) to the variance in BMD at all sites except the lumbar spine. The free estradiol index (E2/SHBG) contributed to whole body BMD (P less than 0.05). For all subjects, there were significant inverse relationships between SHBG and BMD (P less than 0.002), and positive relationships between T/SHBG and BMD (P less than 0.02) for all sites except the lumbar spine. These data suggest that moderate smoking in young women is not associated with low BMD at any site. However, smokers had lower free estradiol and higher SHBG, both of which have been related to increased bone loss in older women.

Variability in both skin thickness and skinfold compressibility affects the relationship between the skinfold caliper reading at a particular site on the body and the actual adipose thickness at that site, thus inducing error in the estimation of body fatness. To investigate this variability, skinfold thickness by caliper and incised depth of subcutaneous adipose tissue were measured at 13 skinfold sites in 6 male and 7 female unembalmed cadavers aged 55 to 94 years. All skin was then removed and its thickness measured at the exact sites of skinfold measurement. The regional patterns for skin thickness were similar in men and women, though women had significantly (P < .05) thinner skin than men at the biceps, chest, supraspinale, and abdominal sites. Mean (SD) skin thickness for each cadaver over all sites ranged from 0.76 mm (0.28 mm) to 1.47 mm (0.43 mm), with an overall mean for men of 1.22 mm (0.36 mm) and for women of 0.98 mm (0.36 mm). The thickness of a double layer of skin expressed as a percentage of skinfold thickness for all cadavers over all 13 sites ranged from 7.1% to 33.4%. Because of their leanness and thicker skin, the mean for men, 22.7% (10.1%), was significantly greater than that for women, 10.8% (6.2%) (P < .0001). Mean skinfold compressibility over all sites was 53.5% (16.4%) in men adn 51.9% (16.5%) in women (not significant). Such marked variability in skinfold compressibility and in the relative contribution of skin thickness to skinfold thickness suggests the need for caution in comparing estimates of fatness by skinfold caliper between different subjects. © 1992 Wiley-Liss, Inc.

We discuss the uncertainty in the predictions for hard scattering cross sections at hadron colliders due to uncertainties in the input parton distributions, using W production at the LHC as an example.

Central exclusive Higgs boson production, pp -> p+H+p, at the LHC can provide important complementary contribution to the comprehensive study of the Higgs sector in a remarkably clean topology. The bb(bar) Higgs decay mode is especially attractive, and for certain BSM scenarios may even become the discovery channel. Obvious requirements for the success of such exclusive measurements are strongly suppressed and controllable backgrounds. One potential source of background comes from additional gluon radiation which leads to a three-jet bb(bar)g final state. We perform an explicit calculation of the subprocesses gg -> q(bar)qg, gg -> ggg in the case of `internal' gluon radiation from the spectator, t-channel screening gluon, when the two incoming active t-channel gluons form a colour octet. We find that the overall contribution of this source of background is orders of magnitude lower than that caused by the main irreducible background resulting from the gg^{PP} -> b(bar)b subprocess. Therefore, this background contribution can be safely neglected., Comment: 19 pages, 5 figures. To be published in Eur. Phys. J. C

We present updated leading-order, next-to-leading order and next-to-next-to-leading order parton distribution functions ("MSTW 2008") determined from global analysis of hard-scattering data within the standard framework of leading-twist fixed-order collinear factorisation in the MSbar scheme. These parton distributions supersede the previously available "MRST" sets and should be used for the first LHC data-taking and for the associated theoretical calculations. New data sets fitted include CCFR/NuTeV dimuon cross sections, which constrain the strange quark and antiquark distributions, and Tevatron Run II data on inclusive jet production, the lepton charge asymmetry from W decays and the Z rapidity distribution. Uncertainties are propagated from the experimental errors on the fitted data points using a new dynamic procedure for each eigenvector of the covariance matrix. We discuss the major changes compared to previous MRST fits, briefly compare to parton distributions obtained by other fitting groups, and give predictions for the W and Z total cross sections at the Tevatron and LHC., 157 pages, 70 figures. Code can be found at http://projects.hepforge.org/mstwpdf/ and in LHAPDF V5.7.0. v3: final version published in EPJC with extended Section 12

We determine the uncertainty on the strong coupling alpha_S due to the experimental errors on the data fitted in global analysis of hard-scattering data, within the standard framework of leading-twist fixed-order collinear factorisation in the MSbar scheme, finding that alpha_S(M_Z^2) = 0.1202^{+0.0012}_{-0.0015} at next-to-leading order (NLO) and alpha_S(M_Z^2) = 0.1171^{+0.0014}_{-0.0014} at next-to-next-to-leading order (NNLO). We do not address in detail the issue of the additional theory uncertainty on alpha_S(M_Z^2), but an estimate is +/-0.003 at NLO and at most +/-0.002 at NNLO. We investigate the interplay between uncertainties on alpha_S and uncertainties on parton distribution functions (PDFs). We show, for the first time, how both these sources of uncertainty can be accounted for simultaneously in calculations of cross sections, and we provide eigenvector PDF sets with different fixed alpha_S values to allow further studies by the general user. We illustrate the application of these PDF sets by calculating cross sections for W, Z, Higgs boson and inclusive jet production at the Tevatron and LHC., Comment: 45 pages, 17 figures. Grids can be found at http://projects.hepforge.org/mstwpdf/ and in LHAPDF V5.7.1. v2: version to appear in EPJC

We recall the main features of the Regge approach used to understand soft interactions at LHC and higher energies. Unitarity tames the power growth of the elastic proton-proton scattering amplitude with energy, and leads to the migration of the secondary particles produced in high-energy proton-proton collisions to larger transverse momenta. We discuss, in qualitative terms, the role of processes containing large rapidity gaps (LRG), and the probability that the gaps survive population by secondaries produced in additional soft interactions. We explain how the Regge diagram corresponding to a LRG event simultaneously describes events with different (single, double, etc.) particle density in the same rapidity interval. We show that the role of these, enhanced, multi-Pomeron diagrams can be studied by measuring multiplicity fluctuations and long-range rapidity correlations between secondaries produced at the Tevatron and the LHC. Finally, we make a list of the characteristic features of the multi-Pomeron description of soft interactions that may be observed at the high energies accessible at the Tevatron and the LHC., Comment: 28 pages, 11 figures, Topical Review to be published in J.Phys.G, based on two lectures by Misha Ryskin at the St. Petersburg Winter School, Gatchina, February 2009

We discuss the factorization breaking observed in diffractive dijet photoproduction by the H1 and ZEUS collaborations at HERA. By considering the effects of rapidity gap survival, hadronisation, migration and NLO contributions, we find that the observed data are compatible with theoretical expectations., Comment: 8 pages. Two paragraphs added to Conclusions. To be published in EPJC

We outline the historical development of MRST/MSTW parton distribution functions (PDFs), and clarify how they should be regarded when compared to the most up-to-date 2008 MSTW sets, noting which sets are now obsolete and the reasons why.

In general, minimum-bias triggers planned for experiments at the LHC miss a considerable fraction of the total number of events. We exemplify the rejection rate using the Durham model of soft high-energy interactions to obtain quantitative estimates of the signals arising from the ATLAS scintillation counters positioned in the rapidity intervals 2, Comment: 7 pages, 2 figures, 3 tables

We calculate the cross section for J/ψ production from gluon jets at LEP via the mechanisms g→ψgg, g→χ c g and g→b b →ψX. We predict about 230 such J/ψ events for 10 6 hadronic decays of the Z, and we show the resulting J/ψ energy and angular distributions.

Precision measurements of Λ MS from deep inelastic scattering traditionally use a fixed renormalization scale μ = Q . This is in contrast to measurements in e + e − annihilation, where “scale dependence” is an important source of uncertainty on the value of Λ MS . We extend our previous determination Λ MS to allow for different scale choices. We find that our previous value of α s ( M z )=0.109 −0.005 +0.004 becomes α s ( M z )=0.109 −0.008 +0.007 when a reasonable variation of scale is included. We discuss the implications of this result for recent attempts to obtain information on the scale of supersymmetry from coupling constant unification.

The very small x behaviour of the gluon distribution in a proton is investigated by solving the Lipatov equation with the nonlinear shadowing term included. We find, with decreasing x , the emergence of an x − λ behaviour and the eventual taming of this singularity by the shadowing term. We compare our dynamically generated gluon with that obtained in a recent QCD structure function analysis which incorporated the Lipatov and shadowing effects.