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1.	Akhunzyanov, R., et al. (författare) Transverse extension of partons in the proton probed in the sea-quark range by measuring the DVCS cross section 2019 Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 793, s. 188-194 Tidskriftsartikel (refereegranskat)abstract We report on the first measurement of exclusive single-photon muoproduction on the proton by COMPASS using 160 GeV/c polarised mu(+) and mu(-) beams of the CERN SPS impinging on a liquid hydrogen target. We determine the dependence of the average of the measured mu(+) and mu(-) cross sections for deeply virtual Compton scattering on the squared four-momentum transfer t from the initial to the final proton. The slope B of the t-dependence is fitted with a single exponential function, which yields B = (4.3 +/- 0.6(stat) (+0.1)(-0.3)vertical bar(sys)) (GeV/c)(-2). This result can be converted into a transverse extension of partons in the proton,root(r(perpendicular to)(2)) = (0.58 +/- 0.04(stat) (+0.01)(-0.02)vertical bar(sys) +/- 0.04(model)) fm. For this measurement, the average virtuality of the photon mediating the interaction is < Q(2)> = 1.8 (GeV/c)(2) and the average value of the Bjorken variable is < X-Bj > = 0.056.
2.	Aghasyan, M., et al. (författare) Light isovector resonances in pi(-) p -> pi(-) pi(-) pi(+)p at 190 GeV/c 2018 Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 98:9 Tidskriftsartikel (refereegranskat)abstract We have performed the most comprehensive resonance-model fit of pi(-)pi(-)pi(+) states using the results of our previously published partial-wave analysis (PWA) of a large data set of diffractive-dissociation events from the reaction pi(-) + p -> pi(-)pi(-)pi(+) +p(recoil) with a 190 GeV/c pion beam. The PWA results, which were obtained in 100 bins of three-pion mass, 0.5 < m(3 pi) < 2.5 GeV/c(2), and simultaneously in 11 bins of the reduced four-momentum transfer squared, 0.1 < t'< 1.0 (GeV/c)(2), are subjected to a resonance-model fit using Breit-Wigner amplitudes to simultaneously describe a subset of 14 selected waves using 11 isovector light-meson states with J(PC) = 0(-+), 1(++), 2(++), 2(-+), 4(++), and spin-exotic 1(-+) quantum numbers. The model contains the well-known resonances pi(1800), a(1)(1260), a(2)(1320), pi(2)(1670), pi(2)(1880), and a(4) (2040). In addition, it includes the disputed pi(1)(1600), the excited states a(1)(1640), a2(1700), and pi(2) (2005), as well as the resonancelike a(1)(1420). We measure the resonance parameters mass and width of these objects by combining the information from the PWA results obtained in the 11 t' bins. We extract the relative branching fractions of the rho(770)pi and f(2)(1270)pi decays of a(2)(1320) and a(4)(2040), where the former one is measured for the first time. In a novel approach, we extract the t' dependence of the intensity of the resonances and of their phases. The t' dependence of the intensities of most resonances differs distinctly from the t' dependence of the nonresonant components. For the first time, we determine the t' dependence of the phases of the production amplitudes and confirm that the production mechanism of the Pomeron exchange is common to all resonances. We have performed extensive systematic studies on the model dependence and correlations of the measured physical parameters.
3.	Aghasyan, M., et al. (författare) Longitudinal double-spin asymmetry A(1)(p) and spin-dependent structure function g(1)(p) of the proton at small values of x and Q(2) 2018 Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 781, s. 464-472 Tidskriftsartikel (refereegranskat)abstract We present a precise measurement of the proton longitudinal double-spin asymmetry A(1)(p) and the proton spin-dependent structure function g(1)(P) at photon virtualities 0.006 (GeV/c)(2) < Q(2) < 1 (GeV/c)(2) in the Bjorken x range of 4 x 10(-5) < x < 4 x 10(-2). The results are based on data collected by the COMPASS Collaboration at CERN using muon beam energies of 160 GeV and 200 GeV. The statistical precision is more than tenfold better than that of the previous measurement in this region. In the whole range of x, the measured values of A(1)(p) and g(1)(P) are found to be positive. It is for the first time that spin effects are found at such low values of x.
4.	Aghasyan, M., et al. (författare) Search for muoproduction of X(3872) at COMPASS and indication of a new state (X)over-tilde(3872) 2018 Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 783, s. 334-340 Tidskriftsartikel (refereegranskat)abstract We have searched for exclusive production of exotic charmonia in the reaction mu N+ -> mu(+)(J/psi pi(+)pi(-))pi N-+/-' using COMPASS data collected with incoming muons of 160 GeV/c and 200 GeV/c momentum. In the J/psi pi(vertical bar)pi mass distribution we observe a signal with a statistical significance of 4.1 sigma. Its mass and width are consistent with those of the X(3872). The shape of the pi(+)pi(-) mass distribution from the observed decay into J/psi pi(+)pi(-) shows disagreement with previous observations for X(3872). The observed signal may be interpreted as a possible evidence of a new charmonium state. It could be associated with a neutral partner of X(3872) with C=-1 predicted by a tetraquark model. The product of cross section and branching fraction of the decay of the observed state into J/psi pi(+)pi(-) is determined to be 71 +/- 28(stat)+/- 39(syst) pb.
5.	Aghasyan, M., et al. (författare) Transverse-momentum-dependent multiplicities of charged hadrons in muon-deuteron deep inelastic scattering 2018 Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 97:3 Tidskriftsartikel (refereegranskat)abstract A semi-inclusive measurement of charged hadron multiplicities in deep inelastic muon scattering off an isoscalar target was performed using data collected by the COMPASS Collaboration at CERN. The following kinematic domain is covered by the data: photon virtuality Q(2) > 1 (GeV/c)(2), invariant mass of the hadronic system W > 5 (GeV/c)(2), Bjorken scaling variable in the range 0.003 < x < 0.4, fraction of the virtual photon energy carried by the hadron in the range 0.2 < z < 0.8, and square of the hadron transverse momentum with respect to the virtual photon direction in the range 0.02 (GeV/c)(2) < P-hT(2) < 3 (GeV/c)(2). The multiplicities are presented as a function of P-hT(2) in three-dimensional bins of x, Q(2), z and compared to previous semi-inclusive measurements. We explore the small-P-hT(2) region, i.e. P-hT(2) < 1 (GeV/c)(2), where hadron transverse momenta are expected to arise from nonperturbative effects, and also the domain of larger P-hT(2), where contributions from higher-order perturbative QCD are expected to dominate. The multiplicities are fitted using a single-exponential function at small P-hT(2) to study the dependence of the average transverse momentum < P-hT(2)> on x, Q(2) and z. The power-law behavior of the multiplicities at large P-hT(2) is investigated using various functional forms. The fits describe the data reasonably well over the full measured range.
6.	Jackura, A., et al. (författare) New analysis of eta pi tensor resonances measured at the COMPASS experiment 2018 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 779, s. 464-472 Tidskriftsartikel (refereegranskat)abstract We present a new amplitude analysis of the eta pi D-wave in the reaction pi(-) p -> eta pi(-) p measured by COMPASS. Employing an analytical model based on the principles of the relativistic S-matrix, we find two resonances that can be identified with the a(2)(1320) and the excited a(2)(1700), and perform a comprehensive analysis of their pole positions. For the mass and width of the a(2) we find M = (1307 +/- 1 6) MeV and Gamma=(112 +/- 1 +/- 8) MeV, and for the excited state a(2)' we obtain M = (1720 +/- 10 +/- 60) MeV and Gamma = (280 +/- 10 +/- 70) MeV, respectively.
7.	Adolph, C., et al. (författare) Azimuthal asymmetries of charged hadrons produced in high-energy muon scattering off longitudinally polarised deuterons 2018 Ingår i: European Physical Journal C. - : SPRINGER. - 1434-6044 .- 1434-6052. ; 78:11 Tidskriftsartikel (refereegranskat)abstract Single hadron azimuthal asymmetries of positive and negative hadrons produced in muon semi-inclusive deep inelastic scattering off longitudinally polarised deuterons are determined using the 2006 COMPASS data and also combined all deuteron COMPASS data. For each hadron charge, the dependence of the azimuthal asymmetry on the hadron azimuthal angle f is obtained by means of a fiveparameter fitting function that besides a f-independent term includes four modulations predicted by theory: sin f, sin 2f, sin 3f and cos f. The amplitudes of the five terms have been extracted, first, for the hadrons in the whole available kinematic region. In further fits, performed for hadrons from a restricted kinematic region, the f-dependence is determined as a function of one of three variables (Bjorken-x, fractional energy of virtual photon taken by the outgoing hadron and hadron transverse momentum), while disregarding the others. Except thef-independent term, all themodulation amplitudes are very small, and no clear kinematic dependence could be observed within experimental uncertainties.
8.	Adolph, C., et al. (författare) Final COMPASS results on the deuteron spin-dependent structure function g(1)(d) and the Bjorken sum rule 2017 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 769, s. 34-41 Tidskriftsartikel (refereegranskat)abstract Final results are presented from the inclusive measurement of deep-inelastic polarised-muon scattering on longitudinally polarised deuterons using a 6LiD target. The data were taken at 160 GeV beam energy and the results are shown for the kinematic range 1 (GeV/c)2 < Q2 < 100 (GeV/c)2 in photon virtuality, 0.004 < x < 0.7 in the Bjorken scaling variable and W > 4GeV/c2 in the mass of the hadronic final state. The deuteron double-spin asymmetry A(1)(d) and the deuteron longitudinal-spin structure function g(1)(d) are presented in bins of x and Q2. Towards lowest accessible values of x, g(1)(d) decreases and becomes consistent with zero within uncertainties. The presented final g(1)(p) values together with the recently published final g(1)(p) values of COMPASS are used to again evaluate the Bjorken sum rule and perform the QCD fit to the g1 world data at next-to-leading order of the strong coupling constant. In both cases, changes in central values of the resulting numbers are well within statistical uncertainties. The flavour singlet axial charge a0, which is identified in the MS renormalisation scheme with the total contribution of quark helicities to the nucleon spin, is extracted at next-to-leading order accuracy from only the COMPASS deuteron data: a0(Q2 = 3 (GeV/c)2) = 0.32 +/- 0.02stat +/- 0.04syst +/- 0.05evol. Together with the recent results on the proton spin structure function g(1)(p), the results on g(1)(d) constitute the COMPASS legacy on the measurements of g1 through inclusive spin-dependent deep inelastic scattering.
9.	Adolph, C., et al. (författare) First measurement of the Sivers asymmetry for gluons using SIDIS data 2017 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 772, s. 854-864 Tidskriftsartikel (refereegranskat)abstract The Sivers function describes the correlation between the transverse spin of a nucleon and the transverse motion of its partons. For quarks, it was studied in previous measurements of the azimuthal asymmetry of hadrons produced in semi-inclusive deep inelastic scattering of leptons off transversely polarised nucleon targets, and it was found to be non-zero. In this letter the evaluation of the Sivers asymmetry for gluons is presented. The contribution of the photon-gluon fusion subprocess is enhanced by requiring two high transverse-momentum hadrons. The analysis method is based on a Monte Carlo simulation that includes three hard processes: photon-gluon fusion, QCD Compton scattering and the leading-order virtual-photon absorption process. The Sivers asymmetries of the three processes are simultaneously extracted using the LEPTO event generator and a neural network approach. The method is applied to samples of events containing at least two hadrons with large transverse momentum from the COMPASS data taken with a 160 GeV/c muon beam scattered off transversely polarised deuterons and protons. With a significance of about two standard deviations, a negative value is obtained for the gluon Sivers asymmetry. The result of a similar analysis for a Collins-like asymmetry for gluons is consistent with zero. (C) 2017 The Author(s). Published by Elsevier B.V.
10.	Adolph, C., et al. (författare) Interplay among transversity induced asymmetries in hadron leptoproduction 2016 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 753, s. 406-411 Tidskriftsartikel (refereegranskat)abstract In the fragmentation of a transversely polarized quark several left-right asymmetries are possible for the hadrons in the jet. When only one unpolarized hadron is selected, it exhibits an azimuthal modulation known as the Collins effect. When a pair of oppositely charged hadrons is observed, three asymmetries can be considered, a di-hadron asymmetry and two single hadron asymmetries. In lepton deep inelastic scattering on transversely polarized nucleons all these asymmetries are coupled with the transversity distribution. From the high statistics COMPASS data on oppositely charged hadron-pair production we have investigated for the first time the dependence of these three asymmetries on the difference of the azimuthal angles of the two hadrons. The similarity of transversity induced single and di-hadron asymmetries is discussed. A new analysis of the data allows quantitative relationships to be established among them, providing for the first time strong experimental indication that the underlying fragmentation mechanisms are all driven by a common physical process.
11.	Adolph, C., et al. (författare) Leading-order determination of the gluon polarisation from semi-inclusive deep inelastic scattering data 2017 Ingår i: European Physical Journal C. - : SPRINGER. - 1434-6044 .- 1434-6052. ; 77:4 Tidskriftsartikel (refereegranskat)abstract Using a novel analysis technique, the gluon polarisation in the nucleon is re-evaluated using the longitudinal double-spin asymmetry measured in the cross section of semi-inclusive single-hadron muoproduction with photon virtuality Q(2) > 1 ( GeV/c)(2). The data were obtained by the COMPASS experiment at CERN using a 160 GeV/c polarised muon beam impinging on a polarised (LiD)-Li-6 target. By analysing the full range in hadron transverse momentum p(T), the different pT-dependences of the underlying processes are separated using a neural-network approach. In the absence of pQCD calculations at next-to-leading order in the selected kinematic domain, the gluon polarisation Delta g/g is evaluated at leading order in pQCD at a hard scale of mu(2) = < Q(2) > = 3( GeV/c)(2). It is determined in three intervals of the nucleon momentum fraction carried by gluons, x(g), covering the range 0.04< x(g)< 0.28 and does not exhibit a significant dependence on xg. The average over the three intervals, < Delta g/g > = 0.113 +/- 0.038(stat) +/- 0.036( syst) at < x(g) > approximate to 0.10, suggests that the gluon polarisation is positive in the measured x(g) range.
12.	Adolph, C., et al. (författare) Multiplicities of charged kaons from deep-inelastic muon scattering off an isoscalar target 2017 Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 767, s. 133-141 Tidskriftsartikel (refereegranskat)abstract Precise measurements of charged-kaon multiplicities in deep inelastic scattering were performed. The results are presented in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y, and the fraction z of the virtual-photon energy carried by the produced hadron. The data were obtained by the COMPASS Collaboration by scattering 160 GeV muons off an isoscalar (LiD)-Li-6 target. They cover the kinematic domain 1 (GeV/c)(2) < Q(2) < 60 (GeV/c)(2) in the photon virtuality, 0.004 < x < 0.4, 0.1 < y < 0.7, 0.20 < z < 0.85, and W > 5 GeV/c(2) in the invariant mass of the hadronic system. The results from the sum of the z-integrated K+ and K- multiplicities at high x point to a value of the non-strange quark fragmentation function larger than obtained by the earlier DSS fit.
13.	Adolph, C., et al. (författare) Multiplicities of charged pions and charged hadrons from deep-inelastic scattering of muons off an isoscalar target 2017 Ingår i: Physics Letters B. - : ELSEVIER SCIENCE BV. - 0370-2693 .- 1873-2445. ; 764, s. 1-10 Tidskriftsartikel (refereegranskat)abstract Multiplicities of charged pions and charged hadrons produced in deep-inelastic scattering were measured in three-dimensional bins of the Bjorken scaling variable x, the relative virtual-photon energy y and the relative hadron energy z. Data were obtained by the COMPASS Collaboration using a 160 GeV muon beam and an isoscalar target ((LiD)-Li-6). They cover the kinematic domain in the photon virtuality Q(2) > 1 (GeV/c) 2, 0.004 < x < 0.4, 0.2 < z < 0.85 and 0.1 < y < 0.7. In addition, a leading-order pQCD analysis was performed using the pion multiplicity results to extract quark fragmentation functions.
14.	Adolph, C., et al. (författare) Resonance production and pi pi S-wave in pi(-) + p -> pi(-) pi(-) pi(+) + p(recoil) at 190 GeV/c 2017 Ingår i: Physical Review D. - : AMER PHYSICAL SOC. - 2470-0010 .- 2470-0029. ; 95:3 Tidskriftsartikel (refereegranskat)abstract The COMPASS collaboration has collected the currently largest data set on diffractively produced pi(-) pi(-) pi(+) final states using a negative pion beam of 190 GeV/c momentum impinging on a stationary proton target. This data set allows for a systematic partial-wave analysis in 100 bins of three-pion mass, 0.5 < m(3 pi) < 2.5 GeV/c(2), and in 11 bins of the reduced four-momentum transfer squared, 0.1 < t' < 1.0 (GeV/c)(2). This two-dimensional analysis offers sensitivity to genuine one-step resonance production, i.e. the production of a state followed by its decay, as well as to more complex dynamical effects in nonresonant 3 pi production. In this paper, we present detailed studies on selected 3p partial waves with J(PC) = 0(-+) ,1(++) ,2(-+) ,2(++) ,and 4(++). In these waves, we observe the well-known groundstate mesons as well as a new narrow axial-vector meson a(1)(1420) decaying into f(0) (980)pi. In addition, we present the results of a novel method to extract the amplitude of the pi(-)pi(+) subsystem with I(G)J(PC) = 0(+)0(++) in various partial waves from the pi(-)pi(-)pi(+) data. Evidence is found for correlation of the f (0)(980) and f(0)(1500) appearing as intermediate pi(-)pi(+) isobars in the decay of the known pi(1800) and pi(2)(1880).
15.	Adolph, C., et al. (författare) Sivers asymmetry extracted in SIDIS at the hard scales of the Drell-Yan process at COMPASS 2017 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 770, s. 138-145 Tidskriftsartikel (refereegranskat)abstract Eight proton transverse-spin-dependent azimuthal asymmetries are extracted in four regions of the photon virtuality Q(2) from the COMPASS 2010 semi-inclusive hadron measurements in deep inelastic muon nucleon scattering. These Q(2) regions correspond to the four regions of the di-muon mass root Q(2) used in the ongoing analyses of the COMPASS Drell-Yan measurements, which allows for a future direct comparison of the nucleon transverse-momentum-dependent parton distribution functions extracted from these two alternative measurements. In addition, for the azimuthal asymmetries induced by the Sivers transverse-momentum-dependent parton distribution function various two-dimensional kinematic dependences are presented. The integrated Sivers asymmetries are found to be positive with an accutacy that appears to be sufficient to test the sign change of the Sivers function predicted by Quantum Chromodynamics.
16.	Adolphi, C., et al. (författare) Exclusive omega meson muoproduction on transversely polarised protons 2017 Ingår i: Nuclear Physics B. - : ELSEVIER SCIENCE BV. - 0550-3213 .- 1873-1562. ; 915, s. 454-475 Tidskriftsartikel (refereegranskat)abstract Exclusive production of omega mesons was studied at the COMPASS experiment by scattering 160GeV/c muons off transversely polarised protons. Five single-spin and three double-spin azimuthal asymmetries were measured in the range of photon virtuality 1(GeV/c)(2) < Q(2) < 10(GeV/c)(2), Bjorken scaling variable 0.003 < xBj < 0.3 and transverse momentum squared of the omega meson 0.05(GeV/c)(2) < p(T)(2) < 0.5(GeV/c)(2). The measured asymmetries are sensitive to the nucleon helicity-flip Generalised Parton Distributions (GPD) Et hat are related to the orbital angular momentum of quarks, the chiral-odd GPDs H-T that are related to the transversity Parton Distribution Functions, and the sign of the pi omega transition form factor. The results are compared to recent calculations of a GPD-based model.
17.	Aghasyan, M., et al. (författare) First Measurement of Transverse-Spin-Dependent Azimuthal Asymmetries in the Drell-Yan Process 2017 Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 119:11 Tidskriftsartikel (refereegranskat)abstract The first measurement of transverse-spin-dependent azimuthal asymmetries in the pion-induced Drell-Yan (DY) process is reported. We use the CERN SPS 190 GeV/c pi(-) beam and a transversely polarized ammonia target. Three azimuthal asymmetries giving access to different transverse-momentum-dependent (TMD) parton distribution functions (PDFs) are extracted using dimuon events with invariant mass between 4.3 GeV/c(2) and 8.5 GeV/c(2). Within the experimental uncertainties, the observed sign of the Sivers asymmetry is found to be consistent with the fundamental prediction of quantum chromodynamics (QCD) that the Sivers TMD PDFs extracted from DY have a sign opposite to the one extracted from semi-inclusive deep-inelastic scattering (SIDIS) data. We present two other asymmetries originating from the pion Boer-Mulders TMD PDFs convoluted with either the nucleon transversity or pretzelosity TMD PDFs. A recent COMPASS SIDIS measurement was obtained at a hard scale comparable to that of these DY results. This opens the way for possible tests of fundamental QCD universality predictions.
18.	Adolph, C., et al. (författare) The spin structure function g(1)(p) of the proton and a test of the Bjorken sum rule 2016 Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 753, s. 18-28 Tidskriftsartikel (refereegranskat)abstract New results for the double spin asymmetry A(1)(p) and the proton longitudinal spin structure function g(1)(p) are presented. They were obtained by the COMPASS Collaboration using polarised 200 GeV muons scattered off a longitudinally polarised NH3 target. The data were collected in 2011 and complement those recorded in 2007 at 160 GeV, in particular at lower values of x. They improve the statistical precision of g(1)(p)(x) by about a factor of two in the region x less than or similar to 0.02. A next-to-leading order QCD fit to the g(1) world data is performed. It leads to a new determination of the quark spin contribution to the nucleon spin, Delta Sigma, ranging from 0.26 to 0.36, and to a re-evaluation of the first moment of g(1)(p). The uncertainty of Delta Sigma is mostly due to the large uncertainty in the present determinations of the gluon helicity distribution. A new evaluation of the Bjorken sum rule based on the COMPASS results for the non-singlet structure function g(1)(NS) (x, Q(2)) yields as ratio of the axial and vector coupling constants vertical bar gA/gV vertical bar = 1.22 +/- 0.05 (stat.) +/- 0.10 (syst.), which validates the sum rule to an accuracy of about 9%.
19.	Adeva, B, et al. (författare) Measurement of proton and nitrogen polarization in ammonia and a test of equal spin temperature 1998 Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 419:1, s. 60-82 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract The 1996 data taking of the SMC experiment used polarized protons to measure the spin-dependent structure function g(1) of the proton. Three liters of solid granular ammonia were irradiated at the Bonn electron linac in order to create the paramagnetic ra
20.	Adeva, B, et al. (författare) Next-to-leading order QCD analysis of the spin structure function g(1) - art. no. 112002 1998 Ingår i: PHYSICAL REVIEW D. - : AMERICAN PHYSICAL SOC. - 0556-2821. ; 5811:11, s. 2002- Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We present a next-to-leading order QCD analysis of the presently available data on the spin structure function g(1) including the final data from the Spin Muon Collaboration. We present results for the first moments of the proton, deuteron, and neutron st
21.	Adeva, B, et al. (författare) Spin asymmetries A(1) of the proton and the deuteron in the low x and low Q(2) region from polarized high energy muon scattering - art. no. 072004 1999 Ingår i: PHYSICAL REVIEW D. - : AMERICAN PHYSICAL SOC. - 0556-2821. ; 6007:7, s. 2004- Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We present the results of the spin asymmetries Al of the proton and the deuteron in the kinematic region extending down to x = 6 x 10(-5) and Q(2) = 0.01 GeV2. The data were taken with a dedicated low x trigger, which required hadron detection in addition
22.	Adeva, B, et al. (författare) The spin-dependent structure function g(1)(x) of the proton from polarized deep-inelastic muon scattering 1997 Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 412:3-4, s. 414-424 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We present a new measurement of the virtual photon proton asymmetry A(1)(P) from deep inelastic scattering of polarized muons on polarized protons in the kinematic range 0.0008 < x < 0.7 and 0.2 < Q(2) < 100 GeV2. With this, the statistical uncertainty of
23.	Apyan, A., et al. (författare) Coherent bremsstrahlung, coherent pair production, birefringence, and polarimetry in the 20-170 GeV energy range using aligned crystals 2008 Ingår i: Physical Review Special Topics - Accelerators and Beams. - 1098-4402. ; 11:4, s. 041001- Tidskriftsartikel (refereegranskat)abstract The processes of coherent bremsstrahlung (CB) and coherent pair production (CPP) based on aligned crystal targets have been studied in the energy range 20-170 GeV. The experimental arrangement allowed for measurements of single photon properties of these phenomena including their polarization dependences. This is significant as the theoretical description of CB and CPP is an area of active debate and development. With the approach used in this paper, both the measured cross sections and polarization observables are predicted very well. This indicates a proper understanding of CB and CPP up to energies of 170 GeV. Birefringence in CPP on aligned crystals is applied to determine the polarization parameters in our measurements. New technologies for high-energy photon beam optics including phase plates and polarimeters for linear and circular polarization are demonstrated in this experiment. Coherent bremsstrahlung for the strings-on-strings (SOS) orientation yields a larger enhancement for hard photons than CB for the channeling orientations of the crystal. Our measurements and our calculations indicate low photon polarizations for the high-energy SOS photons.
24.	Adams, D, et al. (författare) A large Streamer Chamber muon tracking detector in a high-flux fixed-target application 1999 Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 435:3, s. 354-374 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Arrays of limited streamer tubes of the Iarocci type were deployed in our experiment at CERN as part of a forward muon detector system with provisions for the beam to pass through the center of each panel in the array. A total of 16 4 m x 4 m panels were
25.	ADAMS, D, et al. (författare) A NEW MEASUREMENT OF THE SPIN-DEPENDENT STRUCTURE-FUNCTION G(1)(X) OF THE DEUTERON 1995 Ingår i: PHYSICS LETTERS B. ; 357:1-2 Annan publikation (övrigt vetenskapligt/konstnärligt)
26.	Adams, D, et al. (författare) Measurement of the SMC muon beam polarisation using the asymmetry in the elastic scattering off polarised electrons 2000 Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 443:1, s. 1-19 Tidskriftsartikel (refereegranskat)abstract A muon beam polarimeter was built for the SMC experiment at the CERN SPS, for beam energies of 100 and 190 GeV. The beam polarisation is determined from the asymmetry in the elastic scattering off the polarised electrons of a ferromagnetic target whose ma
27.	Adams, D, et al. (författare) Spin structure of the proton from polarized inclusive deep-inelastic muon-proton scattering 1997 Ingår i: PHYSICAL REVIEW D. - : AMER INST PHYSICS. ; 56:9, s. 5330-5358 Recension (övrigt vetenskapligt/konstnärligt)abstract We have measured the spin-dependent structure function g(1)(p) in inclusive deep-inelastic scattering of polarized muons off polarized protons, in the kinematic range 0.003
28.	Adams, D, et al. (författare) The polarized double cell target of the SMC 1999 Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 437:1, s. 23-67 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract The polarized target of the Spin Muon Collaboration at CERN was used for deep inelastic muon scattering experiments during 1993-1996 with a polarized muon beam to investigate the spin structure of the nucleon. Most of the experiments were carried out with
29.	Adams, D, et al. (författare) The spin-dependent structure function g(1)(x) of the deuteron from polarized deep-inelastic muon scattering 1997 Ingår i: PHYSICS LETTERS B. - : ELSEVIER SCIENCE BV. - 0370-2693. ; 396:1-4, s. 338-348 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We present a new measurement of the spin-dependent structure function g(1)(d) of the deuteron from deep inelastic scattering of 190 GeV polarized muons on polarized deuterons. The results are combined with our previous measurements of g(1)(d). A perturbat
30.	Adeva, B, et al. (författare) Large enhancement of deuteron polarization with frequency modulated microwaves 1996 Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 372:3, s. 339-343 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We report a large enhancement of 1.7 in deuteron polarization up to values of 0.6 due to frequency modulation of the polarizing microwaves in a two liter polarized target using the method of dynamic nuclear polarization. This target was used during a deep
31.	Adeva, B, et al. (författare) Polarisation of valence and non-strange sea quarks in the nucleon from semi-inclusive spin asymmetries 1996 Ingår i: PHYSICS LETTERS B. ; 369:1 Annan publikation (övrigt vetenskapligt/konstnärligt)
32.	Adeva, B, et al. (författare) Spin asymmetries A(1) and structure functions g(1) of the proton and the deuteron from polarized high energy muon scattering - art. no. 112001 1998 Ingår i: PHYSICAL REVIEW D. - : AMERICAN PHYSICAL SOC. - 0556-2821. ; 5811:11, s. 2001- Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract We present the final results of the spin asymmetries A(1) and the spin structure functions g(1) of the proton and the deuteron in the kinematic range 0.0008 < x < 0.7 and 0.2 < Q(2) < 100 GeV2. For the determination of A(1), in addition to the usual metho
33.	Badelek, B, et al. (författare) Spin structure function g 1(x,Q2) and the DHGHY integral I(Q2) at low Q*2: Predictions from the GVMD model 2002 Ingår i:* EUROPEAN PHYS JOURNAL. ; C26, s. 45-49 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
34.	Badelek, B, et al. (författare) The photon collider at TESLA 2004 Ingår i: International Journal of Modern Physics A. - 0217-751X. ; 19:30, s. 5097-5186 Forskningsöversikt (refereegranskat)abstract High energy photon colliders (gammagamma,gammae) are based on e(-)e(-) linear colliders where high energy photons are produced using Compton scattering of laser light on high energy electrons just before the interaction point. This paper is a part of the Technical Design Report of the linear collider TESLA.(1) Physics program, possible parameters and some technical aspects of the photon collider at TESLA are discussed.
35.	Dulya, C, et al. (författare) A line-shape analysis for spin-1 NMR signals 1997 Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 398:2-3, s. 109-125 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract An analytic model of the deuteron absorption function has been developed and is compared to experimental NMR signals of deuterated butanol obtained at the SMC experiment in order to determine the deuteron polarization. The absorption function model includ
36.	AMAUDRUZ, P, et al. (författare) A REEVALUATION OF THE NUCLEAR-STRUCTURE FUNCTION RATIOS FOR D, HE, LI-6, C AND CA 1995 Ingår i: NUCLEAR PHYSICS B. - : ELSEVIER SCIENCE BV. - 0550-3213. ; 441:1-2, s. 3-11 Tidskriftsartikel (refereegranskat)abstract We present a re-evaluation of the structure function ratios F-2(He)/F-2(D), F-2(C)/F-2(D) and F-2(Ca)/F-2(D) measured in deep inelastic muon-nucleus scattering at an incident muon momentum of 200 GeV. We also present the ratios F-2(C)/F-2(Li), F-2(Ca)/F-2
37.	Arneodo, M, et al. (författare) Accurate measurement of F-2(d)/F-2(p) and R(d)-R(p) 1997 Ingår i: NUCLEAR PHYSICS B. - : ELSEVIER SCIENCE BV. - 0550-3213. ; 487:1-2, s. 3-26 Tidskriftsartikel (refereegranskat)abstract Results are presented for F-2(d)/F-2(p) and R(d) - R(p) from simultaneous measurements of deep inelastic muon scattering on hydrogen and deuterium targets, at 90, 120, 200 and 280 GeV. The difference R(d) - R(p), determined in the range 0.002 < x < 0.4 at
38.	Arneodo, M, et al. (författare) Measurement of the proton and deuteron structure functions, F-2(p) and F-2(d), and of the ratio sigma(L)/sigma(T) 1997 Ingår i: NUCLEAR PHYSICS B. - : ELSEVIER SCIENCE BV. - 0550-3213. ; 483:1-2, s. 3-43 Tidskriftsartikel (refereegranskat)abstract The muon-proton and muon-deuteron inclusive deep inelastic scattering cross sections were measured in the kinematic range 0.002 < x < 0.60 and 0.5 < Q(2) < 75 GeV2 at incident muon energies of 90, 120, 200 and 280 GeV. These results are based on the full
39.	ARNEODO, M, et al. (författare) MEASUREMENT OF THE PROTON AND THE DEUTERON STRUCTURE FUNCTIONS, F-2(P) AND F-2(D) 1995 Ingår i: PHYSICS LETTERS B. ; 364:2, s. 107-115 Tidskriftsartikel (refereegranskat)
40.	Arneodo, M, et al. (författare) The A dependence of the nuclear structure function ratios 1996 Ingår i: NUCLEAR PHYSICS B. - : ELSEVIER SCIENCE BV. - 0550-3213. ; 481:1-2, s. 3-22 Tidskriftsartikel (refereegranskat)abstract Results are presented for six nuclei from Be to Pb on the structure function ratios F-2(A)/F-2(C)(X) and their A dependence in deep inelastic muon scattering at 200 GeV incident: muon energy. The data cover the kinematic range 0.01 < x < 0.8 with Q(2) ran
41.	Arneodo, M, et al. (författare) The Q(2) dependence of the structure function ratio F-2(Sn)/F-2(C) and the difference R(Sn)-R(C) in deep inelastic muon scattering 1996 Ingår i: NUCLEAR PHYSICS B. - : ELSEVIER SCIENCE BV. - 0550-3213. ; 481:1-2, s. 23-39 Tidskriftsartikel (refereegranskat)abstract The Q(2) dependence of the structure function ratio F-2(Sn)/F-2(C) for 0.01 < x < 0.75 and 1 < Q(2) < 140 GeV2 is reported. For x < 0.1 the size of shadowing decreases linearly with In Q(2) and the maximum rate is about 0.04 at x = 0.01. The rate decrease
42.	ARNEODO, M, et al. (författare) THE STRUCTURE-FUNCTION RATIOS F-2(LI)/F-2(D) AND F-2(C)/F-2(D) AT SMALL-X 1995 Ingår i: NUCLEAR PHYSICS B. - : ELSEVIER SCIENCE BV. - 0550-3213. ; 441:1-2, s. 12-30 Tidskriftsartikel (refereegranskat)abstract We present the structure function ratios F-2(Li)/F-2(D) and F-2(C)/F-2(D) measured in deep inelastic muon-nucleus scattering at a nominal incident muon energy of 200 GeV. The kinematic range 10(-4) < x < 0.7 and 0.01 < Q(2) < 70 GeV2 is covered. For value
43.	Badelek, B, et al. (författare) A model for F-L and R=F-L/F-T at low x and low Q(2) 1997 Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 74:2, s. 297-305 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract A model for the longitudinal structure function F-L at low x and low Q(2) is presented, which includes the kinematical constraint F-L similar to Q(4) as Q(2) --> 0. It is based on the photon-gluon fusion mechanism suitably extrapolated to the region of lo
44.	Badelek, B, et al. (författare) A model of F-2(gamma) at arbitrary Q(2) and the total photon-photon cross-sections at high energies 2001 Ingår i: NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT. - : ELSEVIER SCIENCE BV. - 0168-9002. ; 472:1-2, s. 222-228 Tidskriftsartikel (refereegranskat)abstract A model of the real photon structure function F-2(gamma) which can be used in the low Q(2), low x region is formulated. It includes both the VMD and the QCD components, the latter based on arbitrary parton distributions in the photon and suitably extrapol
45.	Badelek, B, et al. (författare) F-2(gamma) at low Q(2) and sigma(gamma gamma) at high energies 1999 Ingår i: ACTA PHYSICA POLONICA B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254. ; 30:6, s. 1807-1815 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract The parametrisation of the photon structure function in the low Q(2) region is formulated. It includes the VMD contribution and the QCD improved parton model component suitably extrapolated to the low Q(2) region. The parametrisation describes reasonably
46.	Badelek, B, et al. (författare) Parametrization of F-2(gamma) at low Q(2) and of sigma(gamma gamma) and sigma(gammagamma) at high energies - art. no. 074021 2000 Ingår i:* PHYSICAL REVIEW D. - : AMERICAN PHYSICAL SOC. - 0556-2821. ; 6207:7, s. 4021- Tidskriftsartikel (refereegranskat)abstract A parametrization of the real photon structure function F-2(gamma) in the law Q(2), low x region is formulated. It includes both the vector meson dominance (VMD) and the QCD components, the latter suitably extrapolated to the low Q(2) region and based on
47.	Badelek, B (författare) Polarized deep inelastic scattering: Data analysis and results 1997 Ingår i: ACTA PHYSICA POLONICA B. - : ACTA PHYSICA POLONICA B, JAGELLONIAN UNIV, INST PHYSICS. - 0587-4254. ; 28:3-4, s. 543-561 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract Spin properties of the nucleon are discussed based on the ongoing and planned measurements. Role, method and features of radiative corrections applied in the analyses are presented. Future prospects of the spin physics are reviewed.
48.	BADELEK, B, et al. (författare) RADIATIVE CORRECTION SCHEMES IN DEEP-INELASTIC MUON SCATTERING 1995 Ingår i: ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS. - : SPRINGER VERLAG. - 0170-9739. ; 66:4, s. 591-599 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract A description and a detailed comparison of the Mo and Tsai and the Dubna radiative correction schemes is presented. Numerical comparisons made in the kinematical region of the NMC high energy deep inelastic electroproduction experiment are discussed. An o
49.	Badelek, B (författare) Review of fixed target experimental results on the structure of the proton 1996 Ingår i: ACTA PHYSICA POLONICA B. - : POLISH ACAD SCIENCES INST PHYSICS. - 0587-4254. ; 27:6, s. 1145-1173 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract At the end of the fixed-target deep inelastic scattering experimenal programme we summarize the developments on the structure of the proton that were studied in these experiments. We survey the latest structure function data and their QCD interpretation.
50.	BADELEK, B (författare) SHADOWING IN DEUTERON AND THE NEW F-2(N)/F-2(P) MEASUREMENTS 1995 Ingår i: NUCLEAR PHYSICS B. - : ELSEVIER SCIENCE BV. - 0550-3213. ; , s. 9-12 Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract New F-2(n)/F-2(p) measurements at low x by the NMC and E665 are presented. Model calculations, including shadowing in deuteron and being in good agreement with the data are discussed. Shadowing correction to the experimental estimate of the Gottfried sum

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