313 research outputs found
Regge Trajectories of Quark Gluon Bags
Using an exactly solvable statistical model, we discuss the equation of state of large/heavy and short-living bags of the quark gluon plasma (QGP).We argue that the large width of the QGP bags explains not only the observed deficit in the number of hadronic resonances, but also clarifies the reason why the heavy QGP bags cannot be directly observed even as metastable states in the hadronic phase. Also the Regge trajectories of large and heavy QGP bags are established both in vacuum and in a strongly interacting medium. It is shown that, at high temperatures, the average mass and width of the QGP bags behave in accordance with the upper bound of the Regge trajectory asymptotics (the linear asymptotics), whereas, for temperatures below Tн=2 (Tн is the Hagedorn temperature), they obey the lower bound of the Regge trajectory asymptotics (the square root one). Thus, for T Tн=2, these bags demonstrate the standard Regge behavior consistent with the string models.Використовуючи точний розв’язок статистичної моделi, обговорено рiвняння стану великих/важких i короткоживучих мiшкiв кварк-глюонної плазми (КГП). Наведено аргументи того, що велика ширина мiшкiв КГП не тiльки пояснює дефiцит кiлькостi адронних резонансiв, але й причину того, що важкi мiшки КГП не можуть безпосередньо спостерiгатися навiть як метастабiльнi стани в адроннiй фазi. Також знайдено Редже траєкторiї великих i важких мiшкiв КГП як у вакуумi, так i в сильновзаємодiючому середовищi. Доведено, що за високих температур середня маса i ширина мiшкiв КГП пiдкорюються верхнiй границi асимптотики траєкторiї Редже (лiнiйна асимптотика), тодi як для температур, нижчих за Tн=2 (Tн – температура Хагедорна), вони пiдкорюються нижнiй границi асимптотики траєкторiй Редже (асимптотика кореня квадратного). Таким чином, для T Tн=2 цi мiшки демонструють стандартну Редже поведiнку, яка узгоджується з моделями струн
Quark induced excitations of the instanton liquid
The selfconsistent approach to the quark interactions in the instanton liquid
is developed within the tadpole approximation calculating the basic functional
integral. The effective Lagrangian obtained includes colourless scalar field
interacting with quarks. The origin of this dynamical field as an interaction
carrier in soft momentum region is discussed.Comment: 17 pages, 1 figure ps.file. Slightly revised improved versio
Instanton vacuum at finite density of quark matter
We study light quark interactions in the instanton liquid at finite
quark/baryon number density analyzing chiral and diquark condensates and
investigate the behaviors of quark dynamical mass and both condensates together
with instanton liquid density as a function of quark chemical potential. We
conclude the quark impact (estimated in the tadpole approximation) on the
instanton liquid could shift color superconducting phase transition to higher
values of the chemical potential bringing critical quark matter density to the
values essentially higher than conventional nuclear one.Comment: Lattice 2001 (Non-zero temperature and density), 3 pages, 4 figure
Simple Mechanism of Softening Structure Functions at Low Transverse Momentum Region
The relevance of the dipole configurations of quarks in forming nucleus
structure functions is discussed. It is shown that a radiation generated by
dipole configurations while moving relativistically along their axises is
described by distributions which are finite and infrared stable in low
transverse momentum region. It is argued that there is an exponential
transition to the perturbative regime of large transverse momenta and its power
is defined by the distance between the dipole charges in its rest frame
.Comment: 8 page
Chemical freeze-out of light nuclei in high energy nuclear collisions and resolution of the hyper-Triton chemical freeze-out puzzle
Indexación ScopusWe present a summary of the recent results obtained with the novel hadron resonance gas model with the multicomponent hard-core repulsion which is extended to describe the mixtures of hadrons and light (anti-, hyper-)nuclei. A very accurate description is obtained for the hadronic and the light nuclei data measured by STAR at the collision energy The most striking result discussed here is that for the most probable chemical freeze-out scenario for the STAR energy the found parameters allow us to reproduce the values of the experimental ratios S 3 and without fitting. © Published under licence by IOP Publishing Ltd.https://iopscience-iop-org.recursosbiblioteca.unab.cl/article/10.1088/1742-6596/1690/1/01212
Anisotropic flow of charged hadrons, pions and (anti-)protons measured at high transverse momentum in Pb-Pb collisions at TeV
The elliptic, , triangular, , and quadrangular, , azimuthal
anisotropic flow coefficients are measured for unidentified charged particles,
pions and (anti-)protons in Pb-Pb collisions at TeV
with the ALICE detector at the Large Hadron Collider. Results obtained with the
event plane and four-particle cumulant methods are reported for the
pseudo-rapidity range at different collision centralities and as a
function of transverse momentum, , out to GeV/.
The observed non-zero elliptic and triangular flow depends only weakly on
transverse momentum for GeV/. The small dependence
of the difference between elliptic flow results obtained from the event plane
and four-particle cumulant methods suggests a common origin of flow
fluctuations up to GeV/. The magnitude of the (anti-)proton
elliptic and triangular flow is larger than that of pions out to at least
GeV/ indicating that the particle type dependence persists out
to high .Comment: 16 pages, 5 captioned figures, authors from page 11, published
version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/186
Centrality dependence of charged particle production at large transverse momentum in Pb-Pb collisions at TeV
The inclusive transverse momentum () distributions of primary
charged particles are measured in the pseudo-rapidity range as a
function of event centrality in Pb-Pb collisions at
TeV with ALICE at the LHC. The data are presented in the range
GeV/ for nine centrality intervals from 70-80% to 0-5%.
The Pb-Pb spectra are presented in terms of the nuclear modification factor
using a pp reference spectrum measured at the same collision
energy. We observe that the suppression of high- particles strongly
depends on event centrality. In central collisions (0-5%) the yield is most
suppressed with at -7 GeV/. Above
GeV/, there is a significant rise in the nuclear modification
factor, which reaches for GeV/. In
peripheral collisions (70-80%), the suppression is weaker with almost independently of . The measured nuclear
modification factors are compared to other measurements and model calculations.Comment: 17 pages, 4 captioned figures, 2 tables, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/284
Measurement of charm production at central rapidity in proton-proton collisions at TeV
The -differential production cross sections of the prompt (B
feed-down subtracted) charmed mesons D, D, and D in the rapidity
range , and for transverse momentum GeV/, were
measured in proton-proton collisions at TeV with the ALICE
detector at the Large Hadron Collider. The analysis exploited the hadronic
decays DK, DK, DD, and their charge conjugates, and was performed on a
nb event sample collected in 2011 with a
minimum-bias trigger. The total charm production cross section at TeV and at 7 TeV was evaluated by extrapolating to the full phase space
the -differential production cross sections at TeV
and our previous measurements at TeV. The results were compared
to existing measurements and to perturbative-QCD calculations. The fraction of
cdbar D mesons produced in a vector state was also determined.Comment: 20 pages, 5 captioned figures, 4 tables, authors from page 15,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/307
Two-pion Bose-Einstein correlations in central Pb-Pb collisions at = 2.76 TeV
The first measurement of two-pion Bose-Einstein correlations in central Pb-Pb
collisions at TeV at the Large Hadron Collider is
presented. We observe a growing trend with energy now not only for the
longitudinal and the outward but also for the sideward pion source radius. The
pion homogeneity volume and the decoupling time are significantly larger than
those measured at RHIC.Comment: 17 pages, 5 captioned figures, 1 table, authors from page 12,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/388
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
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