536 Search Results

The yields of $$K^0_S$$ mesons have been measured in inelastic p+p interactions at incident projectile momenta of 31, 40 and 80 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ ($$\sqrt{s_{NN}}=7.7, 8.8$$ and 12.3 $$\text {Ge}\hspace{-1.00006pt}\text {V}$$, respectively). The data were recorded by the NA61$$/$$SHINE spectrometer at the CERN Super Proton Synchrotron and the $$K^0_S$$ mesons identified via their decays into $$\pi ^{+} \pi ^{-}$$ pairs. Double-differential distributions are presented as function of transverse momentum and rapidity. The mean multiplicities of $$K^0_S$$ mesons were determined to be $$(5.95 \pm 0.19 (stat) \pm 0.30 (sys)) \times 10^{-2}$$ at 31 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$, $$(7.61 \pm 0.13 (stat) \pm 0.43 (sys)) \timesmore » 10^{-2}$$ at 40 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$ and $$(11.58 \pm 0.12 (stat) \pm 0.55 (sys)) \times 10^{-2}$$ at 80 $$\text {Ge}\hspace{-1.00006pt}\text {V}\!/\!c$$. The results on $$K^{0}_{S}$$ production are compared with the production of charged kaons in corresponding reactions and with model calculations (Epos1.99, SMASH 2.0 and PHSD) as well as with published data from other experiments.« less

The critical point of strongly interacting matter is searched for at the CERN SPS by the NA61/SHINE experiment in central \(^{40}\)Ar + \(^{45}\)Sc collisions at 13 A, 19 A, 30 A, 40 A, and 75 A GeV/c. The dependence of the second-order scaled factorial moments of proton multiplicity distributions on the number of subdivisions in transverse momentum space is measured. The intermittency analysis uses statistically independent data sets for every subdivision in transverse and cumulative-transverse momentum variables. The results obtained do not indicate the searched intermittent pattern. An upper limit on the fraction of correlated protons and the intermittency indexmore » is obtained based on a comparison with the Power-law Model.« less

The NA61/SHINE experiment at the CERN Super Proton Synchrotron studies the onset of deconfinement in strongly interacting matter through a beam energy scan of particle production in collisions of nuclei of varied sizes. This paper presents results on inclusive double-differential spectra, transverse momentum and rapidity distributions and mean multiplicities of $$\pi ^\pm $$, $$K^\pm $$, p and $$\bar{p}$$ produced in $$^{40}\hbox {Ar+}^{45}\hbox {Sc}$$ collisions at beam momenta of 13A, 19A, 30A, 40A, 75A and 150A $$\text{ Ge }\hspace{-1.00006pt}\text{ V }\!/\!c$$. The analysis uses the 10% most central collisions, where the observed forward energy defines centrality. The energy dependence of the $$K^\pmmore » $$/$$\pi ^\pm $$ ratios as well as of inverse slope parameters of the $$K^\pm $$ transverse mass distributions are placed in between those found in inelastic $p+p$ and central Pb + Pb collisions. The results obtained here establish a system-size dependence of hadron production properties that so far cannot be explained either within statistical or dynamical models.« less

This paper reports measurements of two-pion femtoscopic correlations in Be+Be collisions at a beam momentum of 150$$A\,\hbox {GeV}\!/\!c$$ (energy available in the center-of-mass system for nucleon pair $$\sqrt{s_{\text {NN}}} = 16.84$$ GeV) by the NA61/SHINE experiment at the CERN SPS accelerator. The obtained momentum space correlation functions can be well described by a Lévy distributed source model. The transverse mass dependence of the Lévy source parameters is presented, and their possible theoretical interpretations are discussed. The results show that the Lévy exponent $$\alpha $$ is approximately constant as a function of $$m_{\text {T}}$$ , and far from both the Gaussian case of $$\alphamore » = 2$$ or the conjectured value at the critical endpoint, $$\alpha = 0.5$$. The radius scale parameter R shows a slight decrease in $$m_{\text {T}}$$ , which can be explained as a signature of transverse flow. Finally, an approximately constant trend of the intercept parameter $$\lambda $$ as a function of $$m_{\text {T}}$$ was observed, similar to previous NA44 S + Pb results (obtained with a Gaussian approximation, but unlike RHIC results).« less

The critical point of dense, strongly interacting matter is searched for at the CERN SPS in $$^{40}$$Ar  + $$^{45}$$Sc collisions at 150A  Ge V /c. The dependence of second-order scaled factorial moments of proton multiplicity distribution on the number of subdivisions of transverse momentum space is measured. The intermittency analysis is performed using both transverse momentum and cumulative transverse momentum. For the first time, statistically independent data sets are used for each subdivision number. The obtained results do not indicate any statistically significant intermittency pattern. An upper limit on the fraction of correlated proton pairs and the power of the correlationmore » function is obtained based on a comparison with the Power-law Model developed for this purpose.« less

Measurements of $$K^{*}(892)^0$$ resonance production via its $$K^{+}\pi ^{-}$$ decay mode in inelastic p+p collisions at beam momenta 40 and 80 $$\text{ GeV }\!/\!c$$ ($$\sqrt{s_{NN}}=8.8$$ and 12.3 $$\text{ GeV }$$) are presented. The data were recorded by the NA61/SHINE hadron spectrometer at the CERN Super Proton Synchrotron. The template method was used to extract the $$K^{*}(892)^0$$ signal. Transverse momentum and rapidity spectra were obtained. The mean multiplicities of $$K^{*}(892)^0$$ mesons were found to be $$(35.1 \pm 1.3 \mathrm {(stat)} \pm 3.6 \mathrm {(sys))} \cdot 10^{-3}$$ at 40 $$\text{ GeV }\!/\!c$$ and $$(58.3 \pm 1.9 \mathrm {(stat)} \pm 4.9 \mathrm {(sys))}more » \cdot 10^{-3}$$ at 80 $$\text{ GeV }\!/\!c$$. The NA61/SHINE results are compared with the Epos1.99 and Hadron Resonance Gas models as well as with world data. The transverse mass spectra of $$K^{*}(892)^0$$ mesons and other particles previously reported by NA61/SHINE were fitted within the Blast-Wave model. The transverse flow velocities are close to 0.1–0.2 of the speed of light and are significantly smaller than the ones determined in heavy nucleus-nucleus interactions at the same beam momenta.« less

The production of $$K^{0}_{S}$$ mesons in inelastic p+p collisions at beam momentum 158 $$\text{ GeV }/c$$ ($$\sqrt{s_{NN}}=17.3$$ $$\text{ GeV }$$) was measured with the NA61/SHINE spectrometer at the CERN Super Proton Synchrotron. Double-differential distributions were obtained in transverse momentum and rapidity. The mean multiplicity of $$K^{0}_{S}$$ was determined to be $$0.162 \pm 0.001 (stat.) \pm 0.011 (sys.)$$. The results on $$K^{0}_{S}$$ production are compared with model predictions (EPOS 1.99, SMASH 2.0, PHSD and UrQMD 3.4 models) as well as with published world data.