3,195 research outputs found
Overview and Recent Results from BRAHMS
The BRAHMS experiment was designed to measure and characterize in particular
the properties of rapidity dependence of particle production in heavy ion
collisions. The data-taking is now over, results of several years of analysis
have been published and demonstrates several important features of the rapidity
dependence, not envisioned from the start of the RHIC program. The bulk
properties of the system formed at high rapidity resemble that of systems at
lower energies at mid-rapidity when referenced via the baryo-chemical
potential. New physics in AA are essentially observed at mid-rapidity including
the demonstration that high-\pT suppression is a final state effect. Another
key result is that in d+A collisions at forward rapidities where the very low-x
region of the nucleus was probed, a strong suppression of pion production was
observed consistent with the picture of gluon saturation. The latest results
examines the centrality and rapidity dependence of nuclear stopping, the
particle production of pions, collective expansion vs. rapidity, and the baryon
enhancement at intermediate values of \pT .Comment: 8 pages, 6 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennessee Fixed typos and
minor text issues as per organizers review reques
Stopping and Baryon Transport in Heavy Ion Reactions
In this report I will give an experimental overview on nuclear stopping in
hadron collisions, and relate observations to understanding of baryon
transport. Baryon number transport is not only evidenced via net-proton
distributions but also by the enhancement of strange baryons near mid-rapidity.
Although the focus is on high-energy data obtained from pp and heavy ions from
RHIC, relevant data from SPS and ISR will be considered. A discussion how the
available data at higher energy relates and gives information on baryon
junction, quark-diquark breaking will be made.Comment: 8 pages, 7 figures. Invited plenary talk for the 5'th international
conference on Physics and Astrophysics of Quark Gluon Plasma, February 8-12,
2005, Salt Lake City, Kolkata, Indi
Constraining the nuclear gluon distribution in processes at RHIC
A systematic determination of the gluon distribution is of fundamental
interest in understanding the parton structure of nuclei and the QCD dynamics.
Currently, the behavior of this distribution at small (high energy) is
completely undefined. In this paper we analyze the possibility of constraining
the nuclear effects present in using the inclusive observables which
would be measured in the future electron-nucleus collider at RHIC. We
demonstrate that the study of nuclear longitudinal and charm structure
functions allows to estimate the magnitude of shadowing and antishadowing
effects in the nuclear gluon distribution.Comment: 6 pages, 3 eps figure
Dietary habits and lifestyle in school-aged children from Bucharest, Romania
Background. This study evaluated the difference between boys and girls in terms of nutritional status, lifestyle, and dietary habits during school life.
Materials and Methods. A descriptive and observational study was conducted in 2016, in which 251 children, aged 7-17, from 3 elementary schools and a high school inBucharest,Romania, were evaluated. A questionnaire was used to assess food behavior, eating, and lifestyle habits.
Results. Boys had a significantly higher waist circumference (71.18±9) than girls (67.46±9.91) (p=0.004). Thus 27% of boys were overweight or obese compared with only 22% of the girls. Differences were also seen between the two groups in terms of main meals and snacks and following a rhythm of meals: a statistically significant percentage of girls (36.3%) skip breakfast, while most boys (63.8%) take a food package to school. A total of 23.8% of the boys and 24% of the girls state that they eat while sitting in front of the computer or TV.
Conclusions. We found that boys are more overweight or obese than girls. Obesity in the pediatric population of Romania could be explained by the country’s emergence from communism 25 years ago, pattern typical of all Eastern European countries and which currently involve an overexposure of people to fast food, fizzy drinks and sweets, as well as to a high consumption of salt and food additives. Unbalanced and highly caloric food had been preferable to healthy food in the last period. Leisure time is rather spent in front of the TV, tablet, detrimental to rational physical exercise, recreational sports or hiking. The family environment is very important and all our actions should be focused on continuous education about the risks of unhealthy food and a sedentary lifestyle
Overview of Hard processes at RHIC: high-pt light hadron and charm production
An overview of the experimental results on high-pt light hadron production
and open charm production is presented. Data on particle production in
elementary collisions are compared to next-to-leading order perturbative QCD
calculations. Particle production in Au+Au collisions is then compared to this
baseline.Comment: 9 pages, 6 figures, Strange Quark Matter 200
Elliptical Flow in Relativistic Ion Collisions at s^(1/2)= 200 A GeV
A consistent picture of the Au+Au and D+Au, s^1/2 = 200 A GeV measurements at
RHIC obtained with the PHENIX, STAR, PHOBOS and BRAHMS detectors including both
the rapidity and transverse momentum spectra was previously developed with the
simulation LUCIFER. The approach was modeled on the early production of a fluid
of pre-hadrons after the completion of an initial, phase of high energy
interactions. The formation of pre-hadrons is discussed here, in a perturbative
QCD approach as advocated by Kopeliovich, Nemchik and Schmidt. In the second
phase of LUCIFER, a considerably lower energy hadron-like cascade ensues. Since
the dominant collisions occurring in this latter phase are meson-meson in
character while the initial collisions are between baryons, i.e. both involve
hadron sized interaction cross-sections, there is good reason to suspect that
the observed elliptical flow will be produced naturally, and this is indeed
found to be the case.Comment: 7 pages, 6 figure
Rethinking the QCD collisional energy loss
It is shown that to leading order the collisional energy loss of an energetic
parton in the hot quark gluon plasma reads , where
the scale of the coupling is determined by the (parametrically soft) Debye
screening mass. Compared to previous expressions derived by Bjorken and other
authors, , the rectified result takes
into account the running of the coupling, as dictated by quantum corrections
beyond tree level. As one significant consequence, due to asymptotic freedom,
the QCD collisional energy loss becomes independent of the jet energy in the
limit . It is advocated that this resummation improved perturbative
result might be useful to (re-)estimate the collisional energy loss for
temperatures relevant in heavy ion phenomenology.Comment: contribution to "Hot Quarks 2006", Villasimius, Italy, 15-20 May 200
Medium dependence of multiplicity distributions in MLLA
We study the modification of the multiplicity distributions in MLLA due to
the presence of a QCD medium. The medium is introduced though a multiplicative
constant () in the soft infrared parts of the kernels of QCD evolution
equations. Using the asymptotic ansatz for quark and gluons mean multiplicities
and respectively, we study two
cases: fixed as previously considered in the literature, and fixed
. We find opposite behaviors of the dispersion of the multiplicity
distributions with increasing in both cases. For fixed the
dispersion decreases, while for fixed it increases.Comment: LaTeX, 9 pages, 4 eps figures; proceedings of the 3rd International
Conference on Hard and Electromagnetic Probes in High-Energy Nuclear
Collisions - Hard Probes 2008 (Illa de A Toxa, Spain, June 8th-14th 2008
- …