Search results for "production [dark matter]"
showing 10 items of 216 documents
Ground and excited state charmonium production inp+pcollisions ats=200 GeV
2012
We report on charmonium measurements [J/psi (1S), psi' (2S), and chi(c) (1P)] in p + p collisions at root s = 200 GeV. We find that the fraction of J/psi coming from the feed-down decay of psi' and chi(c) in the midrapidity region (vertical bar y vertical bar < 0: 35) is 9.6 +/- 2.4% and 32 +/- 9%, respectively. We also present the p(T) and rapidity dependencies of the J/psi yield measured via dielectron decay at midrapidity (vertical bar y vertical bar < 0.35) and via dimuon decay at forward rapidity (1.2 < vertical bar y vertical bar < 2.2). The statistical precision greatly exceeds that reported in our previous publication [Phys. Rev. Lett. 98, 232002 (2007)]. The new results are compare…
MEASUREMENT OF THE PRODUCTION-RATES OF ETA AND ETA' IN HADRONIC-Z DECAYS
1992
The decays eta --> gammagamma and eta' --> etapi+pi- have been observed in hadronic decays of the Z produced at LEP. The fragmentation functions of both the eta and eta' have been measured. The measured multiplicities for x > 0.1 are 0.298 +/- 0.023 +/- 0.021 and 0.068 +/- 0.018 +/- 0.016 for eta and eta' respectively. While the fragmentation function for the eta is fairly well described by the JETSET Monte Carlo, it is found that the production rate of the eta' is a factor of four less than the corresponding prediction.
Production of Ds** mesons in hadronic Z decays
2002
The production rates of the orbitally excited Ds** mesons, Ds1 and Ds2*, are measured with the 4.1 million hadronic Z decays recorded by the ALEPH detector during 1991--1995. The Ds** mesons are reconstructed in the decay modes Ds1+ -> D*+ K0, Ds1+ -> D*0 K+ and Ds2*+ -> D0 K+. The production rate of the Ds1 is measured to be n(Z->Ds1+-)=(0.52+-0.09+-0.06)%, under the assumption that the two considered decay modes of the Ds1 saturate the branching ratio. The production rate of the Ds2* is determined to be n(Z->Ds2*+-)=(0.83+-0.29+0.07-0.13)%, assuming that the branching fraction of the decay Ds2*+ -> D0 K+ is 45%. The production rates in Z->cc and Z->bbar decays are …
Measurement of the Bs0 lifetime and production rate with Ds−ℓ+ combinations in Z decays
1995
Abstract The lifetime of the Bs0 meson is measured in approximately 3 million hadronic Z decays accumulated using the ALEPH detector at LEP from 1991 to 1994. Seven different Ds− decay modes were reconstructed and combined with an opposite sign lepton as evidence of semileptonic Bs0 decays. Two hundred and eight Ds−l+ candidates satisfy selection criteria designed to ensure precise proper time reconstruction and yield a measured Bs0 lifetime of τ(Bs0) = 1.59−0.15+0.17 (stat) ±0.03 (syst) ps. Using a larger, less constrained sample of events, the product branching ratio is measured to be Br ( b → B s 0 ) · Br(B s 0 → D s − l + νX) = 0.82 ± 0.09 (stat) −0.14+0.13 (syst) %.
Charm counting in b decays
1996
??? The inclusive production of charmed particles in Z--> decays has been measured from the yield of D-0, D+, D-s(+) and Lambda(c)(+) decays in a sample of events with high b purity collected with the ALEPH detector from 1992 to 1995. From these measurements, adding the charmonia production rate and an estimate of the charmed strange baryon contribution, the average number of charm quarks per b decay is determined to be n(c)=1.230+/-0.036+/-0.038+/-0.053, where the uncertainties are due to statistics, systematic effects and branching ratios, respectively.
Constraints on Models for the Higgs Boson with Exotic Spin and Parity inVH→Vbb¯Final States
2014
We present constraints on models containing non-standard-model values for the spin J and parity P of the Higgs boson H in up to 9.7 fb(-1) of p (p) over bar collisions at root s = 1.96 TeV collected with the D0 detector at the Fermilab Tevatron Collider. These are the first studies of Higgs boson J(P) with fermions in the final state. In the ZH -> llb (b) over bar, WH -> l nu b (b) over barb, and ZH -> nu nu b (b) over bar final states, we compare the standard model (SM) Higgs boson prediction, J(P) = 0(+), with two alternative hypotheses, J(P) = 0(-) and J(P) = 2(+). We use a likelihood ratio to quantify the degree to which our data are incompatible with non-SM J(P) predictions for a range…
Inclusive Production of theX(4140)State inpp¯Collisions at D0
2015
We present a study of the inclusive production of the $X(4140)$ with the decay to the $J/\psi \phi$ final state in hadronic collisions. Based on $10.4~\rm{fb^{-1}}$ of $p \overline p $ collision data collected by the D0 experiment at the Fermilab Tevatron collider, we report the first evidence for the prompt production of $X(4140)$ and find the fraction of $X(4140)$ events originating from $b$ hadrons to be $f_b=0.39\pm 0.07 {\rm \thinspace (stat)} \pm 0.10 {\rm \thinspace (syst)} $. The ratio of the non-prompt $X(4140)$ production rate to the $B_s^0$ yield in the same channel is $R=0.19 \pm 0.05 {\rm \thinspace (stat)} \pm 0.07 {\rm \thinspace (syst)}$. The values of the mass $M=4152.5 \pm…
Exotic bcq¯q¯ four-quark states
2019
We carry out a systematic study of exotic $Q{Q}^{\ensuremath{'}}\overline{q}\overline{q}$ four-quark states containing distinguishable heavy flavors, $b$ and $c$. Different generic constituent models are explored in an attempt to extract general conclusions. The results are robust, predicting the same sets of quantum numbers as the best candidates to lodge bound states independently of the model used, the isoscalar ${J}^{P}={0}^{+}$ and ${J}^{P}={1}^{+}$ states. The first state would be strong and electromagnetic-interaction stable, while the second would decay electromagnetically to $\overline{B}D\ensuremath{\gamma}$. Isovector states are found to be unbound, preventing the existence of ch…
Implication of the 750 GeV diphoton resonance on two-Higgs-doublet model and its extensions with Higgs field
2015
We examine the implication of the 750 GeV diphoton resonance on the two-Higgs-doublet model imposing various theoretical and experimental constraints. The production rate of two-Higgs-doublet model is smaller than the cross section observed at the LHC by two order magnitude. In order to accommodate the 750 GeV diphoton resonance, we extend the two-Higgs-doublet model by introducing additional Higgs fields, and focus on two different extensions, an inert complex Higgs triplet and a real scalar septuplet. With the 125 GeV Higgs being agreement with the observed data, the production rate for the 750 GeV diphoton resonance can be enhanced to 0.6 fb for the former and 4.5 fb for the latter. The …
Inclusive production of the η and ω mesons in Z decays, and the muonic branching ratio of the ω
2002
AbstractThe inclusive production of the η and ω(782) mesons is measured in the π+π−π0 decay mode in hadronic Z decays and compared to model predictions. The analysis is based on 4 million hadronic Z decays recorded by the ALEPH detector between 1991 and 1995. The η production rate for xp=pmeson/pbeam>0.10 is found to be 0.355±0.011stat±0.024sys per event, and the ω production rate for xp>0.05 is measured as 0.585±0.019stat±0.033sys per event. The branching ratio for ω→μ+μ− is investigated. A total of 18.1±5.9 events are observed, from which the muonic branching ratio is measured for the first time to be BR(ω→μ+μ−)=(9.0±2.9stat±1.1sys)×10−5.