Total and differential cross sections of the reaction K−p→Λη have been determined for incident K− lab momenta between 1.2 and 1.7 BeVc. No striking resonance formation in the direct channel is seen; in particular, the Y0*(2100) decays not more than 3% via the Λη channel. A prominent forward peak in the differential cross sections indicates some crossed-channel meson-exchange activity. The branching ratio Γ(η→neutrals)Γ(η→π+π−π0) is 3.6±0.6.
No description provided.
We present the first evidence for K ∗ (1780) production in a non-exchange channel. This comes from a study of the reaction K − p → K° π − p at 14.3 GeV/ c . We also present evidence for K ∗ ° (1780) production in the charge exchange channel K − p → K − π + n. No significant K ππ , K ω and K η decay modes are found. The decay angular distribution, the spin-parity assignments and the production mechanism are discussed. With plausible assumptions on the production mechanism, the J P = 3 − spin-parity is favoured.
No description provided.
We have measured the differential cross sections for K − p→ Σ + π − and K − p→ Σ − π + scattering, and the polarization distribution of the Σ + in the first reaction, at K − lab momenta of 3.13 and 3.30 GeV/ c . Our K − p→ Σ + π − cross sections are at least 40% larger than interpolations between measurements at nearby momenta. A comparison using isospin conservation of K − p →Σ + π − , K − p →Σ − π + , and K 0 p → Σ 0 π + cross sections favors our results. The K − p→ Σ + π − differential cross sections have about the same shape and are about twice as large as corresponding K − p→ Λπ 0 differential cross sections across the whole forward region. We discuss the results briefly with reference to simple exchange models.
No description provided.
TMIN = 0.018 GEV**2. TMAX = 4.67 GEV**2.
TMIN = 0.017 GEV**2. TMAX = 4.98 GEV**2.
We present experimental results on a number of K − p reactions at 14.3 GeV/ c that have three bodies in the final state. The final states are K − ω p , K − π p , Λπ + π − , Λ K + K − , Λp p , K ∗ − ω p , Λ(1520) K + K − and Λ(1520) p p . Whenever, with one exception explained by the Zweig rule, there is a K − or a proton in the final state, there is a diffractive-like threshold enhancement in the mass spectrum of the two recoiling particles. These enhancements account for a large fraction of the events in all but the Λπ + π − final state, where they cannot occur, and which is dominated by resonance production. We find evidence for the Q 1 (1300) decaying into K − ω .
THE DIFFRACTION DISSOCIATION CROSS SECTIONS ARE FOR DIFFRACTIVE THRESHOLD ENHANCEMENTS IN THE TWO-BODY MASS SPECTRA (WITHIN 500 MEV CM ENERGY OF THRESHOLD).
We have measured the differential cross sections for the reactions K − p → K 0 n, K − p → Λπ 0 and K − p → Λη , and the Λ polarization distribution for the second reaction, at K − lab momenta of 3.13, 3.30 and 3.59 GeV/ c . The K − p → Λπ 0 polarization is very large: for the combined data in the interval 0.1 < - t < 0.4 GeV 2 , it is 0.98 ± 0.15. The K − p → Λη forward peak is very steep: for the combined data, the slope b in d/d t = a e bt is 16.2 ± 2.3 GeV −2 , whereas it is about 3 GeV −2 for K − p → K 0 n and 5 GeV −2 for K − p → Λπ 0 . There is a dip near t = −0.5 GeV 2 in the K − p → Λη differential cross section , and another near u = −0.3 GeV 2 in the K − p → Λπ 0 differential cross section. The results are compared with predictions of simple models.
No description provided.
No description provided.
No description provided.
Results are presented of a bubble chamber experiment on K − p elastic scattering at 14.3 GeV/ c , in four-momentum transfer range 0.04 < | t | < 2.74 GeV 2 using an initial set of 40 000 events. The total elastic cross section is (2.96 ± 0.10) mb. The results are compared with K + p elastic scattering data at 13.8 GeV/ c , and the effective Regge trajectory is calculated using K − p data from 5 to 100 GeV/ c .
FOR -T < 0.04 GEV**2, CROSS SECTION WAS EXTRAPOLATED TO THE OPTICAL POINT WITH -0.055+-0.040 FOR THE REAL/IMAGINARY RATIO OF THE FORWARD AMPLITUDE.
No description provided.
We present an angular analysis of the $B^{+}\rightarrow K^{\ast+}(\rightarrow K_{S}^{0}\pi^{+})\mu^{+}\mu^{-}$ decay using 9$\,\mbox{fb}^{-1}$ of $pp$ collision data collected with the LHCb experiment. For the first time, the full set of CP-averaged angular observables is measured in intervals of the dimuon invariant mass squared. Local deviations from Standard Model predictions are observed, similar to those in previous LHCb analyses of the isospin-partner $B^{0}\rightarrow K^{\ast0}\mu^{+}\mu^{-}$ decay. The global tension is dependent on which effective couplings are considered and on the choice of theory nuisance parameters.
Results for the CP-averaged observables Fl, Afb and S3–S9. The first uncertainties are statistical and the second systematic.
Results for the optimised observables FL and P1–P'8. The first uncertainties are statistical and the second systematic.
The CP-averaged observable Fl versus q2. The first (second) error bars represent the statistical (total) uncertainties.
A measurement of novel event shapes quantifying the isotropy of collider events is performed in 140 fb$^{-1}$ of proton-proton collisions with $\sqrt s=13$ TeV centre-of-mass energy recorded with the ATLAS detector at CERN's Large Hadron Collider. These event shapes are defined as the Wasserstein distance between collider events and isotropic reference geometries. This distance is evaluated by solving optimal transport problems, using the 'Energy-Mover's Distance'. Isotropic references with cylindrical and circular symmetries are studied, to probe the symmetries of interest at hadron colliders. The novel event-shape observables defined in this way are infrared- and collinear-safe, have improved dynamic range and have greater sensitivity to isotropic radiation patterns than other event shapes. The measured event-shape variables are corrected for detector effects, and presented in inclusive bins of jet multiplicity and the scalar sum of the two leading jets' transverse momenta. The measured distributions are provided as inputs to future Monte Carlo tuning campaigns and other studies probing fundamental properties of QCD and the production of hadronic final states up to the TeV-scale.
IRing2 for HT2>=500 GeV, NJets>=2
IRing2 for HT2>=500 GeV, NJets>=3
IRing2 for HT2>=500 GeV, NJets>=4
We employ data taken by the JADE and OPAL experiments for an integrated QCD study in hadronic e+e- annihilations at c.m.s. energies ranging from 35 GeV through 189 GeV. The study is based on jet-multiplicity related observables. The observables are obtained to high jet resolution scales with the JADE, Durham, Cambridge and cone jet finders, and compared with the predictions of various QCD and Monte Carlo models. The strong coupling strength, alpha_s, is determined at each energy by fits of O(alpha_s^2) calculations, as well as matched O(alpha_s^2) and NLLA predictions, to the data. Matching schemes are compared, and the dependence of the results on the choice of the renormalization scale is investigated. The combination of the results using matched predictions gives alpha_s(MZ)=0.1187+{0.0034}-{0.0019}. The strong coupling is also obtained, at lower precision, from O(alpha_s^2) fits of the c.m.s. energy evolution of some of the observables. A qualitative comparison is made between the data and a recent MLLA prediction for mean jet multiplicities.
Overall result for ALPHAS at the Z0 mass from the combination of the ln R-matching results from the observables evolved using a three-loop running expression. The errors shown are total errors and contain all the statistics and systematics.
Weighted mean for ALPHAS at the Z0 mass determined from the energy evolutions of the mean values of the 2-jet cross sections obtained with the JADE and DURHAMschemes and the 3-jet fraction for the JADE, DURHAM and CAMBRIDGE schemes evaluted at a fixed YCUT.. The errors shown are total errors and contain all the statistics and systematics.
Combined results for ALPHA_S from fits of matched predicitions. The first systematic (DSYS) error is the experimental systematic, the second DSYS error isthe hadronization systematic and the third is the QCD scale error. The values of ALPHAS evolved to the Z0 mass using a three-loop evolution are also given.
An angular analysis of the $B^{0}\rightarrow K^{*0}(\rightarrow K^{+}\pi^{-})\mu^{+}\mu^{-}$ decay is presented. The dataset corresponds to an integrated luminosity of $3.0\,{\mbox{fb}^{-1}}$ of $pp$ collision data collected at the LHCb experiment. The complete angular information from the decay is used to determine $C\!P$-averaged observables and $C\!P$ asymmetries, taking account of possible contamination from decays with the $K^{+}\pi^{-}$ system in an S-wave configuration. The angular observables and their correlations are reported in bins of $q^2$, the invariant mass squared of the dimuon system. The observables are determined both from an unbinned maximum likelihood fit and by using the principal moments of the angular distribution. In addition, by fitting for $q^2$-dependent decay amplitudes in the region $1.1<q^{2}<6.0\mathrm{\,Ge\kern -0.1em V}^{2}/c^{4}$, the zero-crossing points of several angular observables are computed. A global fit is performed to the complete set of $C\!P$-averaged observables obtained from the maximum likelihood fit. This fit indicates differences with predictions based on the Standard Model at the level of 3.4 standard deviations. These differences could be explained by contributions from physics beyond the Standard Model, or by an unexpectedly large hadronic effect that is not accounted for in the Standard Model predictions.
CP-averaged angular observables evaluated by the unbinned maximum likelihood fit.
CP-averaged angular observables evaluated by the unbinned maximum likelihood fit. The first uncertainties are statistical and the second systematic.
CP-asymmetric angular observables evaluated by the unbinned maximum likelihood fit. The first uncertainties are statistical and the second systematic.
Forum