ترغب بنشر مسار تعليمي؟ اضغط هنا

First fragmentation function measurements from full jet reconstruction in heavy-ion collisions at $sqrt{s_{_{rm NN}}}=200$ GeV by STAR

48   0   0.0 ( 0 )
 نشر من قبل Joern Putschke
 تاريخ النشر 2008
  مجال البحث
والبحث باللغة English
 تأليف Joern Putschke




اسأل ChatGPT حول البحث

Measurements of inclusive hadron suppression and di-hadron azimuthal correlations in ultra-relativistic nuclear collisions at RHIC have provided important insights into jet quenching in hot QCD matter, but are limited in their sensitivity due to well-known biases. Full jet reconstruction in heavy-ion collisions would conceptually provide a direct measurement of the energy of the scattered parton before energy loss, alleviating such biases and allowing a measurement of the energy loss probability distribution in a model-independent way from hard probes. In these proceedings we utilize recent progress in the reconstruction of jets in the heavy ion environment and present the first measurement of the fragmentation function from fully reconstructed jets in heavy ion collisions. The fragmentation function measured in central Au+Au collisions at $sqrt{s_{_{rm NN}}}=200$ GeV will be presented and discussed with respect to p+p reference measurements.



قيم البحث

اقرأ أيضاً

We report the first di-jet transverse momentum asymmetry measurements from Au+Au and p+p collisions at RHIC. The two highest-energy back-to-back jets reconstructed from fragments with transverse momenta above 2 GeV/c display a significantly stronger momentum imbalance in heavy-ion collisions than in the p+p reference. When re-examined with correlated soft particles included, we observe that these di-jets then exhibit a unique new feature -- momentum balance is restored to that observed in p+p for a jet resolution parameter of R=0.4, while re-balancing is not attained with a smaller value of R=0.2.
83 - Guannan Xie 2018
We report on the measurements of production of various charmed hadrons in Au+Au collisions at $sqrt{s_{rm{NN}}}$ = 200 GeV (including $D^{0}(overline{D^{0}})$ and $Lambda_{c}^{pm}$) obtained via topological reconstruction, utilizing the Heavy Flavor Tracker at STAR. Precise results on the $D^{0}$ yields from the 2014 data are reported for a wide transverse momentum range down to 0 in various centrality bins. With the high-statistics data collected in 2014 and 2016, and the usage of a supervised machine learning algorithm for signal-to-background separation, the first measurement of the centrality and transverse momentum dependences of $Lambda_{c}^{pm}$ production is shown. Finally, the total charm quark cross section extracted from these measurements in Au+Au collisions at $sqrt{s_{rm{NN}}}$ = 200 GeV is presented.
We report on the first measurement of the charmed baryon $Lambda_c^{pm}$ production at midrapidity ($|y|$ $<$ 1) in Au+Au collisions at $sqrt{s_{NN}}$ = 200 GeV collected by the STAR experiment at the Relativistic Heavy Ion Collider. The $Lambda_c$/$ D^0$ (denoting ($Lambda_c^++Lambda_c^-$)/($D^0+bar{D^0}$)) yield ratio is measured to be 1.08 $pm$ 0.16 (stat.) $pm$ 0.26 (sys.) in the 0--20% most central Au+Au collisions for the transverse momentum ($p_T$) range 3 $<$ $p_T$ $<$ 6 GeV/$c$. This is significantly larger than the PYTHIA model calculations for $p+p$ collisions. The measured $Lambda_c$/$D^0$ ratio, as a function of $p_T$ and collision centrality, is comparable to the baryon-to-meson ratios for light and strange hadrons in Au+Au collisions. Model calculations including coalescence hadronization for charmed baryon and meson formation reproduce the features of our measured $Lambda_c$/$D^0$ ratio.
We report on measurements of dielectron ($e^+e^-$) production in Au$+$Au collisions at a center-of-mass energy of 200 GeV per nucleon-nucleon pair using the STAR detector at RHIC. Systematic measurements of the dielectron yield as a function of trans verse momentum ($p_{rm T}$) and collision centrality show an enhancement compared to a cocktail simulation of hadronic sources in the low invariant-mass region ($M_{ee}<$ 1 GeV/$c^2$). This enhancement cannot be reproduced by the $rho$-meson vacuum spectral function. In minimum-bias collisions, in the invariant-mass range of 0.30 $-$ 0.76 GeV/$c^2$, integrated over the full $p_{rm T}$ acceptance, the enhancement factor is 1.76 $pm$ 0.06 (stat.) $pm$ 0.26 (sys.) $pm$ 0.29 (cocktail). The enhancement factor exhibits weak centrality and $p_{rm T}$ dependence in STARs accessible kinematic regions, while the excess yield in this invariant-mass region as a function of the number of participating nucleons follows a power-law shape with a power of 1.44 $pm$ 0.10. Models that assume an in-medium broadening of the $rho$ meson spectral function consistently describe the observed excess in these measurements. Additionally, we report on measurements of $omega$ and $phi$-meson production through their $e^+e^-$ decay channel. These measurements show good agreement with Tsallis Blast-Wave model predictions as well as, in the case of the $phi$-meson, results through its $K^+K^-$ decay channel. In the intermediate invariant-mass region (1.1$<M_{ee}<$ 3 GeV/$c^2$), we investigate the spectral shapes from different collision centralities. Physics implications for possible in-medium modification of charmed hadron production and other physics sources are discussed.
We report the STAR measurements of dielectron ($e^+e^-$) production at midrapidity ($|y_{ee}|<$1) in Au+Au collisions at $sqrt{s_{rm NN}}$ = 200,GeV. The measurements are evaluated in different invariant mass regions with a focus on 0.30-0.76 ($rho$- like), 0.76-0.80 ($omega$-like), and 0.98-1.05 ($phi$-like) GeV/$c^{2}$. The spectrum in the $omega$-like and $phi$-like regions can be well described by the hadronic cocktail simulation. In the $rho$-like region, however, the vacuum $rho$ spectral function cannot describe the shape of the dielectron excess. In this range, an enhancement of 1.77$pm$0.11(stat.)$pm$0.24(sys.)$pm$0.33(cocktail) is determined with respect to the hadronic cocktail simulation that excludes the $rho$ meson. The excess yield in the $rho$-like region increases with the number of collision participants faster than the $omega$ and $phi$ yields. Theoretical models with broadened $rho$ contributions through interactions with constituents in the hot QCD medium provide a consistent description of the dilepton mass spectra for the measurement presented here and the earlier data at the Super Proton Synchrotron energies.
التعليقات
جاري جلب التعليقات جاري جلب التعليقات
سجل دخول لتتمكن من متابعة معايير البحث التي قمت باختيارها
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا