SHORT LIVED RESONANCES IN ALICE

2007 ◽  
Vol 16 (07n08) ◽  
pp. 2463-2469 ◽  
Author(s):  
A. BADALÀ ◽  
R. BARBERA ◽  
F. BLANCO ◽  
A. PULVIRENTI ◽  
F. RIGGI ◽  
...  
Keyword(s):  
Invariant Mass ◽  
Decay Product ◽  
Hadronic Decay ◽  
Particle Identification ◽  
Combinatorial Background ◽  
Mass Analysis

The ability of the ALICE detector to reconstruct the K*(892)0 resonance in p – p and Pb – Pb collisions at LHC energies has been investigated, by means of a detailed study of simulated events. PYTHIA events for p – p collisions and HIJING events for Pb – Pb collisions have been generated and fully reconstructed. The K*(892)0 was identified by its hadronic decay into Kπ through invariant mass analysis. The combinatorial background has been estimated using an event-mixing technique for p – p events and a like-sign technique for the Pb – Pb ones. The role of the particle identification of the decay product is also discussed.

scholarly journals Role of scalar $$a_0(980)$$ in the single Cabibbo suppressed process $$D^+ \rightarrow \pi ^{+} \pi ^{0} \eta $$

2020 ◽  
Vol 80 (11) ◽  
Author(s):  
Man-Yu Duan ◽  
Jun-Ya Wang ◽  
Guan-Ying Wang ◽  
En Wang ◽  
De-Min Li
Keyword(s):  
Invariant Mass ◽  
Mass Distributions ◽  
Unitary Approach ◽  
Chiral Unitary Approach ◽  
Free Parameters ◽  
Cabibbo Suppressed ◽  
Dalitz Plots

AbstractTaking into account that the scalar $$a_0(980)$$ a 0 ( 980 ) can be dynamically generated from the pseudoscalar-pseudoscalar interaction within the chiral unitary approach, we have studied the single Cabibbo suppressed process $$D^+\rightarrow \pi ^+\pi ^0\eta $$ D + → π + π 0 η . We find clear peaks of $$a_0(980)^+$$ a 0 ( 980 ) + and $$a_0(980)^0$$ a 0 ( 980 ) 0 in the $$\pi ^+\eta $$ π + η and $$\pi ^0\eta $$ π 0 η invariant mass distributions, respectively. The predicted Dalitz plots of $$D^+\rightarrow \pi ^+\pi ^0\eta $$ D + → π + π 0 η also manifest the significant signals for $$a_0(980)^+$$ a 0 ( 980 ) + and $$a_0(980)^0$$ a 0 ( 980 ) 0 states. The uncertainties of the results due to the free parameters are also discussed. Our study shows that the process $$D^+\rightarrow \pi ^+\pi ^0\eta $$ D + → π + π 0 η can be used to explore the nature of the scalar $$a_0(980)$$ a 0 ( 980 ) , thus we encourage the experimental physicists to measure this reaction with more precision.

scholarly journals Improved Event Mixing for Resonance Yield Extraction

Proceedings ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 26
Author(s):  
Adrian Fereydon Nassirpour
Keyword(s):  
Invariant Mass ◽  
New Method ◽  
Combinatorial Background ◽  
Proton Proton ◽  
Proton Collisions ◽  
Particle Pairs ◽  
Proton Proton Collisions

Resonance particles, such as the K*(892) meson, are reconstructed from the invariant mass (M i n v ) distribution of possible particle pairs. To extract the yield with the highest precision, the combinatorial background must be determined as precisely as possible. An event-mixed M i n v distribution is often used to describe the combinatorial background. However, this distribution will not contain the mini-jet-like structures present inside an event. This analysis introduces a new re-weighing scheme, where two M i n v distributions of like-sign particles in the same-event and in mixed-events are used to correct the mixed-event background estimate for the mini-jet-like structure. Using PYTHIA 8.2 generated proton-proton collisions at s NN = 5.02 TeV, it is shown that the new method can be used to more accurately describe the combinatorial background.

scholarly journals The role of N*(2120) nucleon resonance in KΛ(1520) photon and hadronic productions

2014 ◽  
Vol 29 ◽  
pp. 1460244
Author(s):  
Ju-Jun Xie ◽  
En Wang ◽  
Bo-Chao Liu ◽  
J. Nieves
Keyword(s):  
Experimental Data ◽  
Invariant Mass ◽  
Cross Sections ◽  
Dalitz Plot ◽  
Total Cross Sections ◽  
Effective Lagrangian ◽  
Hadronic Production ◽  
Current Experimental Data ◽  
Theoretical Results

The associate KΛ(1520) photon and hadronic production in the γp → K+Λ(1520), pp → pK+Λ(1520) and π-p → K0Λ(1520) reactions are investigated within the effective Lagrangian approach and the isobar model. We are interested in the contribution from the N*(2120) (previously called N*(2080)) resonance, which has a significant coupling to the KΛ(1520) channel. The theoretical results show that the current experimental data for the γp → K+Λ(1520) reaction favor the existence of the N*(2120) resonance, and that these measurements can be used to further constrain its properties. We present results, including the N*(2120) contribution, for total cross sections of the γp → K+Λ(1520), π-p → K0Λ(1520), and pp → pK+Λ(1520) reactions. For this latter one, we also calculate invariant mass and Dalitz plot distributions.

scholarly journals Strangeness production in Pb-Pb collisions at LHC energies with ALICE

2018 ◽  
Vol 171 ◽  
pp. 13007 ◽  
Author(s):  
Michal Šefčík
Keyword(s):  
Heavy Ion ◽  
Hadronic Decay ◽  
Particle Identification ◽  
Strangeness Production ◽  
Ion Collisions ◽  
Decay Products ◽  
Central Rapidity ◽  
Momentum Spectra ◽  
Strangeness Enhancement ◽  
Transverse Momentum Spectra

The results on the production of strange and multi-strange hadrons (K0S, Λ, Ξ and Ω) measured with ALICE in Pb-Pb collisions at the top LHC energy of [see formula in PDF] = 5.02 TeV are reported. Thanks to its excellent tracking and particle identification capabilities, ALICE is able to measure weakly decaying particles through the topological reconstruction of the identified hadronic decay products. Results are presented as a function of centrality and include transverse momentum spectra measured at central rapidity, pT-dependent Λ/K0S ratios and integrated yields. A systematic study of strangeness production is of fundamental importance for determining the thermal properties of the system created in ultrarelativistic heavy ion collisions. In order to study strangeness enhancement, the yields of studied particles are normalised to the corresponding measurement of pion production in the various centrality classes. The results are compared to measurements performed at lower energies, as well as to different systems and to predictions from statistical hadronization models.

DILEPTON ANALYSIS IN THE HADES SPECTROMETER FOR 12C+12C AT 2 AGEV

2005 ◽  
Vol 20 (02n03) ◽  
pp. 602-605
Author(s):  
◽  
J. OTWINOWSKI ◽  
G. AGAKICHIEV ◽  
C. AGODI ◽  
H. ALVAREZ-POLL ◽  
...  
Keyword(s):  
Invariant Mass ◽  
Signal Reconstruction ◽  
Combinatorial Background ◽  
Background Reconstruction ◽  
Light Mesons ◽  
Dilepton Signal ◽  
Mass Reconstruction

The identification of the light mesons in the HADES spectrometer is based on an invariant mass reconstruction of their decay into e+e- pairs. In the dilepton (e+e-) signal reconstruction, particularly important is the reduction of a huge combinatorial background arising from wrong combinations of e+ and e- to unlike sign pairs. Methods of the dilepton signal and combinatorial background reconstruction in the HADES spectrometer will be presented.

scholarly journals Search for a Λnn bound state in Pb-Pb collisions with ALICE at the LHC

2018 ◽  
Vol 192 ◽  
pp. 00045 ◽  
Author(s):  
Annalisa Mastroserio
Keyword(s):  
Multivariate Data Analysis ◽  
Bound States ◽  
Decay Channel ◽  
Nuclear Interaction ◽  
Bound State ◽  
Particle Identification ◽  
Combinatorial Background ◽  
Multivariate Approach ◽  
Exotic State ◽  
Alice Experiment

The extreme energy densities reached at the LHC lead to the production of a significant amount of baryons and strangeness. Such a regime allows for an increased production of potentially existing exotic QCD bound states containing nuclei and strange hadrons. An interesting measurement for the phenomenology of the nuclear interaction is the presence of a neutral bound state constituted by one Λ and two neutrons. The excellent particle identification, tracking and vertexing performance of the ALICE experiment allow for the search of this exotic bound state in the decay channel Λnn →3H+π- in Pb-Pb collisions. In order to improve detection of this state despite the presence of a huge combinatorial background, the extraction of the signal is performed by means of a multivariate approach with the TMVA (Toolkit for Multivariate Data Analysis with ROOT). So far the indication for the existence of the Λnn state was reported only by the HypHI Collaboration, so the observation by ALICE would crucially contribute to the study of such an exotic state.

PROJECTION OF A MEASUREMENT OF THE NONPHOTONIC ELECTRON v2 IN Au + Au COLLISIONS AT STAR

2011 ◽  
Vol 20 (08) ◽  
pp. 1701-1708
Author(s):  
BING-CHU HUANG ◽  
YI-FEI ZHANG ◽  
ZI-PING ZHANG ◽  
ZHANG-BU XU ◽  
XIN DONG
Keyword(s):  
Invariant Mass ◽  
Time Projection Chamber ◽  
Time Of Flight ◽  
Heavy Flavor ◽  
Combinatorial Background ◽  
Plane Method ◽  
Event Plane ◽  
Quark Decays ◽  
Time Projection ◽  
Star Detector

We present a method of measuring the elliptic flow (v2) of nonphotonic electrons from heavy flavor quark decays using the STAR detector at RHIC in Au + Au collisions at [Formula: see text]. Inclusive electrons are identified in the pT range 0.5–4 GeV /c at mid-rapidity -1 < η < 0 by the STAR time projection chamber (TPC) and time-of-flight detector. Photonic e+e- pairs with characteristic low invariant mass are reconstructed in the TPC and their v2 is measured using the standard event plane method by subtracting the combinatorial background in the dN/dΔϕ distributions in each pT bin. The nonphotonic electron v2 and its propagated error can be derived from the inclusive and photonic electron v2. We estimate the necessary statistics and errors of nonphotonic electron v2 for a more recent RHIC run.

scholarly journals JET CORRELATIONS WITH IDENTIFIED PARTICLES FROM PHENIX: METHODS AND RESULTS

2007 ◽  
Vol 16 (10) ◽  
pp. 3160-3167 ◽  
Author(s):  
◽  
ANNE SICKLES
Keyword(s):  
Particle Production ◽  
Azimuthal Angle ◽  
Charged Hadron ◽  
Particle Identification ◽  
Particle Type ◽  
Particle Correlations ◽  
Robust Techniques ◽  
Show Evidence ◽  
Jet Fragmentation

Azimuthal angle two particle correlations have been shown to be a powerful probe for extracting novel features of the interaction between hard scattered partons and the medium produced in Au + Au collisions at RHIC. At intermediate pT, 2–5 GeV/c, the jets have been shown to be significantly modified in both their particle composition and their angular distribution compared to p + p collisions. Additionally, angular two particle correlations with identified hadrons provide information on the possible role of modified hadronization scenarios such as partonic recombination, which might allow medium modified jet fragmentation by connecting hard scattered partons to low pT thermal partons. PHENIX has excellent particle identification capabilities and has developed robust techniques for extracting jet correlations from the large underlying event. We present recent PHENIX results from Au + Au collisions for a variety of pT and particle type combinations. We also present p + p measurements as a baseline. We show evidence that protons and anti-protons in the pT region of enhanced baryon and anti-baryon single particle production are produced in close angle pairs of opposite charge and that the strong modifications to the away side shape observed for charged hadron correlations are also present when baryons are correlated.

scholarly journals FAMILY NONUNIVERSAL Z′ AND b → sγ DECAY

2003 ◽  
Vol 18 (08) ◽  
pp. 545-552 ◽  
Author(s):  
RAMAZAN SEVER ◽  
AYTEKIN AYDEMIR
Keyword(s):  
B Meson ◽  
Branching Ratio ◽  
Hadronic Decay ◽  
Model Parameters ◽  
Cp Asymmetry ◽  
Decay Modes ◽  
The Family

We have calculated the branching ratio and CP asymmetry of B → Xsγ decay within the family nonuniversal Z′ models. We have established certain bounds on the model parameters using the present experimental bounds. We also comment on the role of family nonuniversality in the hadronic decay modes of the B meson.

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