vol. 6, p. 393 (9 pages)
•abstract
In this proceedings contribution, we review recent calculations of the dynamics of the chromo-Weibel instability in the quark-gluon plasma. This instability is present in gauge theories which possess a one-particle distribution function which, in the local rest frame, is momentum-space anisotropic. The conditions necessary for triggering this instability can be present already in the color-glass-condensate initial state or dynamically generated by the rapid longitudinal expansion of the matter created in a heavy-ion collision. Using the hard-loop framework, we study the case that the one-particle distribution function possesses an arbitrary initial momentum anisotropy that increases in time due to longitudinal free streaming. The resulting three-dimensional dynamical equations for the chromofield evolution are solved numerically. We find that there is regeneration of the longitudinal pressure due to unstable plasma modes; nevertheless, the system seems to maintain a high-degree of momentum-space anisotropy. Despite this anisotropy, we find that there is rapid longitudinal thermalization of the plasma due to the non-linear mode couplings inherent in the unstable evolution.
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https://www.actaphys.uj.edu.pl/S/6/2/393/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/393
DOI
https://doi.org/10.5506/APhysPolBSupp.6.393
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 393 (2013)
vol. 6, p. 403 (6 pages)
•abstract
Polarization properties of turbulent stochastically inhomogeneous ultrarelativistic QED plasma are studied. It is shown that the sign of nonlinear turbulent Landau damping corresponds to an instability of the spacelike modes and, for sufficiently large turbulent fields, to an actual instability of a system.
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https://www.actaphys.uj.edu.pl/S/6/2/403/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/403
DOI
https://doi.org/10.5506/APhysPolBSupp.6.403
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 403 (2013)
vol. 6, p. 409 (9 pages)
•abstract
Collisions of lead nuclei have been studied at the CERN SPS since 1994. A review is presented of the evidence for the production of deconfined matter, the location of the energy of the onset of deconfinement and the search for the critical point of strongly interacting matter.
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https://www.actaphys.uj.edu.pl/S/6/2/409/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/409
DOI
https://doi.org/10.5506/APhysPolBSupp.6.409
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 409 (2013)
vol. 6, p. 419 (9 pages)
•abstract
The NA61/SHINE experiment aims to discover the critical point of strongly interacting matter and study properties of the onset of deconfinement. It also performs precise hadron production measurements for the neutrino and cosmic rays experiments. These goals are being achieved by measurements of hadron production properties in nucleus–nucleus, proton–proton and proton/pion–nucleus interactions as a function of collision energy and size of the colliding nuclei. This contribution presents preliminary results from the NA61 ion program on single-particle spectra and identified particle multiplicity fluctuations in \(p+p\) interactions at the CERN SPS. Comparisons with results from \(p+p\) and Pb+Pb collisions obtained by the NA49 experiment are shown.
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https://www.actaphys.uj.edu.pl/S/6/2/419/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/419
DOI
https://doi.org/10.5506/APhysPolBSupp.6.419
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 419 (2013)
vol. 6, p. 429 (8 pages)
•abstract
Results from the Beam Energy Scan (BES) program conducted recently by STAR experiment at the RHIC are presented. The data from Phase-I of the BES program collected in Au+Au collisions at center-of-mass energies (\(\sqrt {s_{NN}}\)) of 7.7, 11.5, 19.6, 27, and 39 GeV cover a wide range of baryon chemical potential \(\mu _{B}\) (100–400 MeV) in the QCD phase diagram. Results from the BES Phase-I related to the “turn-off” of strongly interacting quark-gluon plasma (sQGP) signatures and signals of QCD phase boundary are reported. In addition to this, an outlook is presented for the future BES Phase-II program and a possible fixed target program at STAR.
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https://www.actaphys.uj.edu.pl/S/6/2/429/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/429
DOI
https://doi.org/10.5506/APhysPolBSupp.6.429
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 429 (2013)
vol. 6, p. 437 (7 pages)
•abstract
We report the higher order moments of the net-charge multiplicity distributions for the Au+Au collisions at \(\sqrt {s}_{NN} = 7.7\), 11.5, 19.6, 27, 39, 62.4 and 200 GeV in the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The energy and centrality dependence of higher moments and their products (such as \(\sigma ^2/M\), \(S\sigma \) and \(\kappa \sigma ^{2}\)) are presented. The data are also compared to Poisson expectations and Hadron Resonance Gas model calculations.
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https://www.actaphys.uj.edu.pl/S/6/2/437/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/437
DOI
https://doi.org/10.5506/APhysPolBSupp.6.437
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 437 (2013)
vol. 6, p. 445 (6 pages)
•abstract
We report the energy and centrality dependence of dynamical kurtosis for Au + Au collisions at \(\sqrt {s_{NN}} = 7.7\), 11.5, 19.6, 27, 39, 62.4 and 200 GeV at RHIC. The dynamical kurtosis of net-proton is compared to that of total-proton. The results are also compared with AMPT model calculations.
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https://www.actaphys.uj.edu.pl/S/6/2/445/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/445
DOI
https://doi.org/10.5506/APhysPolBSupp.6.445
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 445 (2013)
vol. 6, p. 451 (6 pages)
•abstract
The interplay between the strong and electromagnetic force in high energy nucleus–nucleus collisions was studied experimentally and theoretically in our earlier works. This effect appeared to result in very large distortions in spectra of charged pions produced in the collision. It was also found to bring new, independent information on the space-time evolution of the non-perturbative process of particle production. In this paper, we present our new results on the influence of the spectator-induced electromagnetic force on spectra of charged particles produced in two different Pb-induced reactions. For the first time, we also address the topic of \(p+A\) collisions in view of obtaining information about their centrality and nuclear break-up, both subjects being of importance in the context of the new \(p+A\) data collected at the LHC.
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https://www.actaphys.uj.edu.pl/S/6/2/451/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/451
DOI
https://doi.org/10.5506/APhysPolBSupp.6.451
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 451 (2013)
vol. 6, p. 457 (6 pages)
•abstract
We present some results pertaining quantities which are regarded as good indicators of the pseudo-critical temperatures for the deconfinement and partial chiral restoration transitions using a polynomial form for the Polyakov potential part and an extended version of the NJL model which includes 6- and 8-quark interaction terms. Some comparisons with results from the lattice formulation of QCD (lQCD) are performed and results for the location of the critical endpoint in the phase diagram are also presented. It is shown that the comparison with lQCD results favours a moderately strong OZI-violating 8-quark interaction term.
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https://www.actaphys.uj.edu.pl/S/6/2/457/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/457
DOI
https://doi.org/10.5506/APhysPolBSupp.6.457
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 457 (2013)
vol. 6, p. 463 (7 pages)
•abstract
This contribution reports on the results obtained in the two recently published papers [A. Bialas, A. Bzdak, K. Zalewski, Phys. Lett. B710, 332 (2012), A. Bialas, K. Zalewski, Acta Phys. Pol. B 43, 1357 (2012)] demonstrating that data of the STAR Collaboration show a substantial asymmetric component in the rapidity distribution of the system created in central Au–Au collisions, implying that boost invariance is violated on the event-by-event basis even at the mid c.m. rapidity.
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https://www.actaphys.uj.edu.pl/S/6/2/463/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/463
DOI
https://doi.org/10.5506/APhysPolBSupp.6.463
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 463 (2013)
vol. 6, p. 471 (8 pages)
•abstract
We present an overview of collective flow phenomena and dihadron correlations measurements from the CMS experiment at the LHC. Fourier components of the anisotropic azimuthal distribution, ranging from the second to the sixth component, are obtained using different analysis techniques, which have different sensitivities to non-flow and flow fluctuation effects. Utilizing a novel and unique high-\(p_{\rm T}\) single-track high-level trigger, the results are presented over a broad \(p_{\rm T}\) range up to approximately 60 GeV/\(c\), as a function of pseudorapidity and collision centrality. These new data will provide essential information on both the hydrodynamic properties of the medium at low \(p_{\rm T}\) and path length dependence of in-medium parton energy loss at high \(p_{\rm T}\). Dihadron correlations are measured over a wide acceptance and \(p_{\rm T}\) range. Long-range near-side (“ridge”) correlation structures are observed from low \(p_{\rm T}\) (1 GeV/\(c\)) to very high \(p_{\rm T}\) (at least 20 GeV/\(c\)).
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https://www.actaphys.uj.edu.pl/S/6/2/471/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/471
DOI
https://doi.org/10.5506/APhysPolBSupp.6.471
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 471 (2013)
vol. 6, p. 479 (6 pages)
•abstract
Measurement by ALICE of the elliptic flow coefficient (\(v_2\)) of strange and multi-strange particles (\(K^{0}_{\rm S}\), \(K^{\pm }\), \({\mit \Lambda }\), \({\mit \Xi }\), \({\mit \Omega }\), \(\phi \)) as a function of transverse momentum, \(p_{\rm T}\) are compared with those of charged pions and (anti-) protons measured at mid-rapidity in Pb–Pb collisions at \(\sqrt {s_{NN}}=2.76\) TeV. The mass splitting and the constituent quark number (\(n_q\)) scaling of \(v_2\) are studied as a function of collision centrality. \(v_2/n_q\) versus \(p_{\rm T}/n_q\) scales within 20% for all identified particles for \(p_{\rm T}/n_q\sim 1.2\) GeV/\(c\), while \(n_q\) scaling of \(v_2\) in transverse kinetic energy (\(m_{\rm T}-m_0\)) is broken over the low \((m_{\rm T}-m_0)/n_q\) region. The \(p_{\rm T}\) differential \(v_2\) values are compared to the viscous hydrodynamical (VISH2+1) model calculation and to the STAR measurements in Au–Au collisions at \(\sqrt {s_{NN}}=200\) GeV. The model calculations can reproduce the main features of identified particle \(v_2\) at low \(p_{\rm T}\). The differential flow of \(\phi \) indicates a larger radial flow at LHC than that at RHIC, while the flow of \({\mit \Xi }\) and \({\mit \Omega }\) is similar to that measured by STAR for Au–Au collisions at \(\sqrt {s_{NN}} = 200\) GeV.
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https://www.actaphys.uj.edu.pl/S/6/2/479/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/479
DOI
https://doi.org/10.5506/APhysPolBSupp.6.479
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 479 (2013)
vol. 6, p. 485 (6 pages)
•abstract
Mixed harmonic charge dependent azimuthal correlations at mid-rapid-ity in Pb–Pb collisions at \(\sqrt {s_{NN}}=2.76\) TeV were measured with the ALICE detector at the LHC. A clear charge dependence for a series of correlations is observed both via the multi-particle cumulant and the event plane methods. Implications from these measurements for the possible effects of local parity violation in QCD and for models which incorporate azimuthal anisotropic flow and “effective” local charge conservation on the kinetic freeze-out surface are discussed.
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https://www.actaphys.uj.edu.pl/S/6/2/485/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/485
DOI
https://doi.org/10.5506/APhysPolBSupp.6.485
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 485 (2013)
vol. 6, p. 491 (8 pages)
•abstract
Bose–Einstein correlations of pairs of identical charged pions produced in hadronic \(Z\) decays are analyzed for various jet configurations, varying from narrow two-jet events to well-separated three-jet events. Parametrizations suggested by the \(\tau \)-model are used to fit the Bose–Einstein correlation function both as a function of the invariant four-momentum difference and of its components in the Longitudinal Center of Mass frame. The resulting values of the radii are found to depend on the jet structure of the event.
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https://www.actaphys.uj.edu.pl/S/6/2/491/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/491
DOI
https://doi.org/10.5506/APhysPolBSupp.6.491
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 491 (2013)
vol. 6, p. 499 (8 pages)
•abstract
The properties of a helix-like shaped QCD string are studied in the context of the Lund fragmentation model. The model predictions are supported by the experimental data. There are similarities between particle correlations stemming from the helix-like string structure and those commonly attributed to the Bose–Einstein interference.
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https://www.actaphys.uj.edu.pl/S/6/2/499/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/499
DOI
https://doi.org/10.5506/APhysPolBSupp.6.499
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 499 (2013)
vol. 6, p. 507 (6 pages)
•abstract
It has been recently noticed that transverse momenta (\(p_{\rm T}\)) distributions observed in high energy production processes exhibit remarkably universal scaling behavior. This is seen when they are in some suitable variable, replacing the usual \(p_{\rm T}\). On the other hand, it is also known that transverse momenta distributions in general follow a power-like Tsallis distribution, rather than an exponential Boltzmann–Gibbs, with a (generally energy dependent) nonextensivity parameter \(q\). We now show that it is possible to choose a suitable variable such that \(p_{\rm T}\) distributions of particles produced in proton–proton interactions in a wide energy range can be fitted by the same Tsallis distribution (with the same, energy independent, value of the \(q\)-parameter). Similar scaling behavior in nucleus–nucleus collisions is also observed. The possible dynamical origin of the \(q\) parameter used in these fits will be discussed.
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https://www.actaphys.uj.edu.pl/S/6/2/507/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/507
DOI
https://doi.org/10.5506/APhysPolBSupp.6.507
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 507 (2013)
vol. 6, p. 513 (6 pages)
•abstract
Peripheral one-tube model has shown to be a nice tool for dynamically understanding several aspects of ridge structures in long-range two-particle correlations, observed experimentally and obtained also in our model calculations using NexSPheRIO code. Here, we study an extension of the model, to initial configurations with several peripheral tubes distributed randomly in azimuth. We show that the two-particle correlation is almost independent of the number of tubes, although the flow distribution becomes indeed strongly event dependent. In our picture, the ridge structures are causally connected not only in the longitudinal direction but also in azimuth.
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https://www.actaphys.uj.edu.pl/S/6/2/513/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/513
DOI
https://doi.org/10.5506/APhysPolBSupp.6.513
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 513 (2013)
vol. 6, p. 519 (6 pages)
•abstract
The Large Hadron Collider has provided collisions of Pb ions at \(\sqrt {s_{NN}}\! =\! 2.76\) TeV. At these energies a significant number of baryons are produced per event, enabling the study of two-baryon correlations. The matter produced in these collisions is described in the frame of hydrodynamics, which predicts a decrease of the apparent source size with transverse mass of the particle. The femtoscopic analysis for baryons, presented here, enables to test this prediction at masses much higher than pions. Baryon yields reported by ALICE are below expectations from thermal models. Annihilation in final-state baryon rescattering has been proposed as an explanation. Such processes should also be reflected in baryon–antibaryon correlations, which are presented here.
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https://www.actaphys.uj.edu.pl/S/6/2/519/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/519
DOI
https://doi.org/10.5506/APhysPolBSupp.6.519
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 519 (2013)
vol. 6, p. 525 (6 pages)
•abstract
CMS results on the observables measured at high pseudorapidities (\(3.0\!\lt \!|\eta |\!\lt \!5.2\)) are presented. The results give an insight into Multi Parton Interactions (MPI), Underlying Event (UE) and QCD evolution.
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https://www.actaphys.uj.edu.pl/S/6/2/525/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/525
DOI
https://doi.org/10.5506/APhysPolBSupp.6.525
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 525 (2013)
vol. 6, p. 531 (8 pages)
•abstract
New LHC data on top quark \(p_{\rm T}\)-spectra obtained by the CMS Collaboration in \(pp\) collisions at \(\sqrt s=7000\) GeV are analyzed in the framework of \(z\)-scaling. The results are compared with DØ data on top quark differential cross section measurements at the Fermilab Tevatron collider at \(\sqrt s=1960\) GeV. Flavour independence of the scaling function \(\psi (z)\) observed in \(pp\) and \(p \bar p\) interactions over a wide collision energy range \(\sqrt s=19\)–1960 GeV is verified. This property of \(\psi (z)\) was found for different hadrons from \(\pi \)-meson up to \({\mit \Upsilon }\) particle. The flavour independence of \(\psi (z)\) is used as indication on self-similarity of top quark production. A tendency to saturation of \(\psi (z)\) at low \(z\) for the top quark is demonstrated.
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https://www.actaphys.uj.edu.pl/S/6/2/531/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/531
DOI
https://doi.org/10.5506/APhysPolBSupp.6.531
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 531 (2013)
vol. 6, p. 539 (6 pages)
•abstract
With increasing luminosities at the LHC, the jet-studies become more accessible. With rising statistics and excellent detector capabilities, possibility emerges to identify jets as quarks or gluons to study and understand how differences in their fragmentation properties influence final particle spectra. We propose a method to separate jets into quark-like and gluon-like samples which can be performed directly on data without the necessity to rely on Monte Carlo. We study the fragmentation of the selected jets and compare to reference samples of quarks and gluons.
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https://www.actaphys.uj.edu.pl/S/6/2/539/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/539
DOI
https://doi.org/10.5506/APhysPolBSupp.6.539
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 539 (2013)
vol. 6, p. 545 (6 pages)
•abstract
The energy loss per unit path length of a highly energetic parton scattering elastically in a weakly coupled quark-gluon plasma is studied as an initial value problem. The approach is designed to study unstable plasmas but in the case of an equilibrium plasma the well known result is reproduced. An extremely prolate plasma, where the momentum distribution is infinitely elongated along one direction, is considered here. The energy loss is shown to be strongly time and directionally dependent and its magnitude can much exceed the energy loss in equilibrium plasma.
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https://www.actaphys.uj.edu.pl/S/6/2/545/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/545
DOI
https://doi.org/10.5506/APhysPolBSupp.6.545
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 545 (2013)
vol. 6, p. 551 (9 pages)
•abstract
Certain analysis methods have emerged recently that claim to reveal “higher harmonic flows” in more-central \(A\)–\(A\) collisions at the RHIC and LHC. But pQCD calculations describe the same structures quantitatively.
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https://www.actaphys.uj.edu.pl/S/6/2/551/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/551
DOI
https://doi.org/10.5506/APhysPolBSupp.6.551
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 551 (2013)
vol. 6, p. 561 (6 pages)
•abstract
In this paper, we discuss the factorization of the logarithms of energy in the Color Glass Condensate framework.
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https://www.actaphys.uj.edu.pl/S/6/2/561/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/561
DOI
https://doi.org/10.5506/APhysPolBSupp.6.561
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 561 (2013)
vol. 6, p. 567 (6 pages)
•abstract
Single inclusive particle production in high-energy \(p\)+Pb collisions is computed with factorization formulas. We use the unintegrated gluon distribution obtained by solving the running-coupling Balitsky–Kovchegov equation and constrained by \(e+p\) scattering data, and model the nuclear target as an assembly of the nucleons with fluctuations. We show our prediction for single inclusive particle spectra and nuclear modification factor in \(p\)+Pb collisions at the LHC [J.L. Albacete et al. , Nucl. Phys. A897,1 (2013)].
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https://www.actaphys.uj.edu.pl/S/6/2/567/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/567
DOI
https://doi.org/10.5506/APhysPolBSupp.6.567
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 567 (2013)
vol. 6, p. 573 (6 pages)
•abstract
We show that saturation can manifest itself in central–forward dijet production in \(p\)–\(A\) collisions. In spite of large transverse momenta of the jets, the almost back-to-back dijet configurations are able to probe gluon density at low \(x\) and low \(k_{\rm t}\). We perform our study in the framework of high energy factorization with the unintegrated gluon density given by a nonlinear QCD evolution equation. We show that the formalism can successfully account for features measured in \(e\)–\(p\) and \(p\)–\(p\) data and it predicts significant suppression of the central–forward jet decorrelations in \(p\)–Pb compared to \(p\)–\(p\), which we attribute to saturation of gluon density in the nucleus.
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https://www.actaphys.uj.edu.pl/S/6/2/573/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/573
DOI
https://doi.org/10.5506/APhysPolBSupp.6.573
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 573 (2013)
vol. 6, p. 579 (7 pages)
•abstract
Some important recent results on subnuclear diffractive phenomena obtained at HERA are reviewed and new issues in nucleon tomography are discussed.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/579/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/579
DOI
https://doi.org/10.5506/APhysPolBSupp.6.579
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 579 (2013)
vol. 6, p. 587 (11 pages)
•abstract
We present the theory of hard exclusive processes, at medium and asymptotical energies, illustrated through some selected examples.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/587/pdf
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https://www.actaphys.uj.edu.pl/S/6/2/587
DOI
https://doi.org/10.5506/APhysPolBSupp.6.587
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 587 (2013)
vol. 6, p. 599 (6 pages)
•abstract
The Large Hadron Collider forward experiment measured very forward neutral particle spectra in LHC proton–proton collisions in early 2010. In this paper, we will discuss the transverse momentum spectra of neutral pion at the 7 TeV proton–proton collision and the inclusive photon energy spectra at the 900 GeV proton–proton collisions. The spectra in both collision energies are also compared with the predictions of several hadronic interaction models that are often used for high energy particle physics and for modeling ultrahigh-energy cosmic ray showers.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/599/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/599
DOI
https://doi.org/10.5506/APhysPolBSupp.6.599
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 599 (2013)
vol. 6, p. 605 (8 pages)
•abstract
I review the state of affairs of the soft QCD physics program in the CMS experiment. Several new results have been released for public display over the last year. In particular, there are new CMS results on identified particle spectra, and several new Underlying Event measurements. I will discuss in general lines the scope of these measurements and the interpretation of the results.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/605/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/605
DOI
https://doi.org/10.5506/APhysPolBSupp.6.605
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 605 (2013)
vol. 6, p. 613 (7 pages)
•abstract
We review the implementation of a model for multiple partonic interactions in Herwig++. Moreover, we show how recent studies on the colour structure of events in Herwig++ led to a significant improvement in the description of soft inclusive observables in \(pp\) interactions at the LHC.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/613/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/613
DOI
https://doi.org/10.5506/APhysPolBSupp.6.613
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 613 (2013)
vol. 6, p. 621 (7 pages)
•abstract
The Lund dipole model DIPSY is based on BFKL evolution and saturation. It can be applied to collisions between electrons, protons, and nuclei. In this paper, I present some recent results for exclusive final states in inelastic collisions, a method to generate final states in diffractive excitation, and some results for collisions with nuclei.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/621/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/621
DOI
https://doi.org/10.5506/APhysPolBSupp.6.621
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 621 (2013)
vol. 6, p. 629 (6 pages)
•abstract
We report on charm production at the LHC. The production of single \(c \bar c\) pairs is calculated in the \(k_{\rm t}\)-factorization approach with different unintegrated gluon distributions. Examples of transverse momentum distributions for charmed mesons are presented and compared to recent experimental results from the LHC. Some missing strength is observed for most of UGDFs. Furthermore, we discuss production of two \(c \bar c\) pairs within double-parton scattering (DPS) and single-parton scattering (SPS) mechanisms. Surprisingly, large cross sections comparable to single \(c \bar c\) pair production are predicted. We discuss first experimental results from LHCb Collaboration on production of pairs of \(D\) mesons of the same flavour.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/629/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/629
DOI
https://doi.org/10.5506/APhysPolBSupp.6.629
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 629 (2013)
vol. 6, p. 635 (6 pages)
•abstract
\(W\), \(Z\) and low mass Drell–Yan production cross sections in proton–proton collisions at \(\sqrt {s}=7\) TeV have been measured with \(W\rightarrow \mu \nu _{\mu }\), \(Z\rightarrow \mu \mu \), \(Z\rightarrow e e\), \(Z\rightarrow \tau \tau \) and \(\gamma ^{*}\rightarrow \mu \mu \) channels in the LHCb detector. The cross section results are consistent with theoretical predictions calculated at next-to-next-to-leading order (NNLO) with different proton parton distribution functions (PDFs).
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/635/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/635
DOI
https://doi.org/10.5506/APhysPolBSupp.6.635
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 635 (2013)
vol. 6, p. 641 (7 pages)
•abstract
Due to its unique pseudorapidity coverage and to the possibility of extending the measurement to low transverse momenta, LHCb is able to provide important input to the understanding of particle production and energy flow in a kinematical range where QCD models have large uncertainties. The measurements are performed in a pseudorapidity range \(2 \lt \eta \lt 5\) which corresponds to the main detector acceptance of the LHCb spectrometer. The measurement of energy flow is compared to predictions given by several Monte Carlo event generators, which model the underlying event activity in different ways. Associative \(J/\psi \) and open charm cross-sections has been investigated in the context of multiple parton interactions at gluon densities achievable at LHC.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/641/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/641
DOI
https://doi.org/10.5506/APhysPolBSupp.6.641
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 641 (2013)
vol. 6, p. 649 (6 pages)
•abstract
Recent high precision measurements of inclusive jets, dijet and trijet production in deep inelastic scattering and photoproduction at HERA are reviewed. The data are compared to NLO QCD predictions. The value of the strong coupling is extracted from jet cross section measurements.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/649/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/649
DOI
https://doi.org/10.5506/APhysPolBSupp.6.649
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 649 (2013)
vol. 6, p. 655 (6 pages)
•abstract
During the past years, measurements of the proton structure at the HERA \(ep\) collider have steadily improved in precision. The most recent results on the proton structure and parton densities are presented. The low \(Q^{2}\) measurements of the longitudinal structure function \(F_{\rm L}\) and the comparison to phenomenological low \(x\) models are described.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/655/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/655
DOI
https://doi.org/10.5506/APhysPolBSupp.6.655
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 655 (2013)
vol. 6, p. 661 (6 pages)
•abstract
In the framework of QCD stochastic vacuum model, we show that colour particle losses its colour propagating through the QCD vacuum medium. At large distances colour disappears completely.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/661/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/661
DOI
https://doi.org/10.5506/APhysPolBSupp.6.661
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 661 (2013)
vol. 6, p. 667 (8 pages)
•abstract
I review the analysis of \(\nu _{e}\) and \(\bar \nu _{e}\) disappearance experiments in terms of neutrino oscillations in the framework of 3+1 neutrino mixing.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/667/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/667
DOI
https://doi.org/10.5506/APhysPolBSupp.6.667
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 667 (2013)
vol. 6, p. 675 (6 pages)
•abstract
The Standard Model includes neutrinos as massless particles, but neutrino oscillations showed that neutrinos are not massless. A simple extension of adding gauge singlet fermions to the particle spectrum allows normal Yukawa mass terms for neutrinos. The smallness of the neutrino masses can be well understood within the seesaw mechanism. We analyse two cases of the minimal extension of the Standard Model when one or two right-handed fields are added to the three left-handed fields. A second Higgs doublet is included in our model. We calculate the one-loop radiative corrections to the mass parameters which produce mass terms for the neutral leptons. In both cases, we numerically analyse light neutrino masses as functions of the heavy neutrinos masses. Parameters of the model are varied to find light neutrino masses that are compatible with experimental data of solar \(\Delta m^2_\odot \) and atmospheric \(\Delta m^2_{\rm atm}\) neutrino oscillations for normal and inverted hierarchy.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/675/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/675
DOI
https://doi.org/10.5506/APhysPolBSupp.6.675
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 675 (2013)
vol. 6, p. 681 (6 pages)
•abstract
The detection of ultra high energy cosmic rays with \(E\gt 10^{19}\) eV implies the existence of high energy neutrinos, originating from extragalactic sources. Neutrinos are suitable messenger particles, pointing back to the origin of cosmic rays when produced in local interactions. Extragalactic neutrino sources are among others gamma-ray bursts (GRBs) and active galactic nuclei (AGN), where protons are accelerated to high energies, collide and produce secondaries, which decay among others in neutrinos. Here, the focus will be on proton–proton interactions in AGN. First results for the target densities \(n_{\mathrm {H}}\), for FR-I galaxies will be presented.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/681/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/681
DOI
https://doi.org/10.5506/APhysPolBSupp.6.681
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 681 (2013)
vol. 6, p. 687 (7 pages)
•abstract
The IceCube neutrino telescope detects neutrinos in the energy range from \(\mathcal {O}\)(10 GeV) up to the PeV scale. One of its primary goals is the detection of high-energy neutrinos connected with cosmic-ray acceleration and propagation. In this contribution, we introduce strategies to search for these neutrinos and highlight recent results in connection with these topics. The search for localized, point-like neutrino sources was performed on three years of data from partial configurations of the detector. The search for extremely high energy (EHE) neutrinos with two years of IceCube data includes the first year of data from the complete IceCube configuration. The results of both searches are compatible with the background expectation but the latter observes two interesting events with a \(p\)-value of 2.2\(\sigma \).
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/687/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/687
DOI
https://doi.org/10.5506/APhysPolBSupp.6.687
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 687 (2013)
vol. 6, p. 695 (8 pages)
•abstract
This paper covers the results of a search for the Standard Model Higgs boson in proton–proton collisions with the ATLAS detector at the LHC. The datasets used correspond to integrated luminosities of approximately 5.0 fb\(^{-1}\) collected at \(\sqrt {s}=7\) TeV in 2011 and 5.5 fb\(^{-1}\) at \(\sqrt {s}= 8\) TeV in 2012. Individual searches in the channels \(H \rightarrow ZZ^{(*)} \rightarrow 4l\), \(H\to \gamma \gamma \) and \(H \rightarrow WW \rightarrow l\nu l\nu \) in the 8 TeV data are combined with previously published results of searches for \(H \rightarrow ZZ^{(*)} \rightarrow 4l\), \(H\to \gamma \gamma \), \(H \rightarrow WW \rightarrow l\nu l\nu \), \(H \rightarrow b\bar b\) and \(H \rightarrow \tau \tau \) in the 7 TeV data and results from improved analyses of the channels \(H \rightarrow ZZ^{(*)} \rightarrow 4l\), \(H\to \gamma \gamma \) in the 7 TeV data. Clear evidence for the production of a neutral boson with a measured mass of \(126.0 \pm 0.4\)(stat) \(\pm ~0.4\)(sys) GeV is presented. This observation, which has a significance of 5.9 standard deviations is compatible with the production and decay of the Standard Model Higgs boson. Searches for signs of physic beyond the Standard Model, in a large variety of signatures are also presented with any experimental evidence.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/695/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/695
DOI
https://doi.org/10.5506/APhysPolBSupp.6.695
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 695 (2013)
vol. 6, p. 703 (6 pages)
•abstract
The search for evidence of beyond Standard Model Higgs bosons is an integral part of the Higgs boson studies at the LHC. This article reviews recent beyond Standard Model Higgs boson searches using 2–5 fb\(^{-1}\) of 7 TeV LHC proton–proton collision data recorded by the ATLAS detector. No significant deviations from the background expectations are found and corresponding constraints on physics beyond the Standard Model are obtained.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/703/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/703
DOI
https://doi.org/10.5506/APhysPolBSupp.6.703
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 703 (2013)
vol. 6, p. 709 (6 pages)
•abstract
In the years 1992–2007 the H1 and ZEUS detectors at the HERA accelerator collected large-luminosity data samples. They provided a high precision and wide kinematic range in the photon virtuality \(Q^2\) and Bjorken \(x\) scaling variable for studying Deep Inelastic Scattering (DIS) processes at HERA. The longitudinal lepton-beam polarisation of HERA II gave a unique opportunity to study the helicity structure of the electroweak interaction, proton content, as well as to test the Standard Model. Some of the newest and most precise results from both collaborations are presented here.
direct link to the full text (pdf)
https://www.actaphys.uj.edu.pl/S/6/2/709/pdf
link to the articles list
https://www.actaphys.uj.edu.pl/S/6/2/709
DOI
https://doi.org/10.5506/APhysPolBSupp.6.709
cite as
Acta Phys. Pol. B Proc. Suppl. 6, 709 (2013)
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