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nucl-th Update: 2010-09-10

SciTes
0
1009.1632 [abs pdf who comments(0)]
Title: Critical Phenomena in DIS
Authors: L. L. Jenkovszky, Andrea Nagy, S. M. Troshin, Jolan Turoczy, N. E. Tyurin

Saturation in deep inelastic scattering (DIS) and deeply virtual Compton scattering (DVCS) is associated with a phase transition between the partonic gas, typical of moderate $x$ and $Q^2$, and partonic fluid appearing at increasing $Q^2$ and decreasing Bjorken $x$. In the statistical interpretation of DIS, the large-$x,(1-x)^n$ factor in the SF is associated with a statistical distribution (perfect gas), while the low-$x$, Regge behaved factor $x^{b(Q^2)}$ produces deviations from the perfect gas and ultimately leads to a gas-liquid phase transition. In this paper we do not intend to propose another parametrization of the structure function; instead we suggest a new insight into the internal structure of the nucleon, as seen in DIS, and its connection with that revealed in high-energy nucleons and heavy-ion collisions.

SciTes
0
1009.1656 [abs pdf who comments(0)]
Title: Chiral asymmetry and axial anomaly in magnetized relativistic matter
Authors: E. V. Gorbar, V. A. Miransky, I. A. Shovkovy

The induced axial current and the chiral anomaly are studied in the normal phase of magnetized relativistic matter. A special attention is paid to the role of the chiral shift parameter Delta, leading to a relative shift of the longitudinal momenta in the dispersion relations of opposite chirality fermions. In the Nambu-Jona-Lasinio model, it is shown directly from the form of the gap equation that Delta necessarily exists in the normal phase in a magnetic field. By making use of the gauge invariant point-splitting regularization, we then show that the presence of Delta essentially modifies the form of the axial current, but does not affect the conventional axial anomaly relation. By recalculating the axial current with the proper-time regularization, we conclude that the result is robust with respect to a specific regularization scheme used.

SciTes
0
1009.1726 [abs pdf who comments(0)]
Title: Consistent alpha-cluster description of the 12C (0^+_2) resonance
Authors: S. I. Fedotov, O. I. Kartavtsev, A. V. Malykh

The near-threshold 12C (0^+_2) resonance provides unique possibility for fast helium burning in stars, as predicted by Hoyle to explain the observed abundance of elements in the Universe. Properties of this resonance are calculated within the framework of the alpha-cluster model whose two-body and three-body effective potentials are tuned to describe the alpha - alpha scattering data, the energies of the 0^+_1 and 0^+_2 states, and the 0^+_1-state root-mean-square radius. The extremely small width of the 0^+_2 state, the 0_2^+ to 0_1^+ monopole transition matrix element, and transition radius are found in remarkable agreement with the experimental data. The 0^+_2-state structure is described as a system of three alpha-particles oscillating between the ground-state-like configuration and the elongated chain configuration whose probability exceeds 0.9.

SciTes
0
1009.1778 [abs pdf who comments(0)]
Title: Light and heavy at the end of the funnel
Authors: Eef van Beveren, George Rupp

We show that, by taking a bare mass spectrum with constant spacings for the quark-antiquark propagators, which is subject to considerable mass shifts from meson loops, one adequately describes a large variety of mesonic resonances, from the light scalars to the b-bbar states. All our results indicate that a harmonic-oscilator spectrum with universal frequency, in combination with coupled-channel effects, does a much better job than the q-barq spectrum of the funnel potential.

SciTes
0
1009.1812 [abs pdf who comments(0)]
Title: Virial Expansion of the Nuclear Equation of State
Authors: Ruslan Maganaa, Hua Zhenga, Aldo Bonasera

We study the equation of state (EOS) of nuclear matter as function of density. We expand the energy per particle (E/A) of symmetric infinite nuclear matter in powers of the density to take into account 2,3,. . .,N-body forces. New EOS are proposed by fitting ground state properties of nuclear matter (binding energy, compressibility and pressure) and assuming that at high densities a second order phase transition to the Quark Gluon Plasma (QGP) occurs. The latter phase transition is due to symmetry breaking at high density from nuclear matter (locally color white) to the QGP (globally color white). In the simplest implementation of a second order phase transition we calculate the critical exponent ? by using Landau's theory of phase transition. We find ? = 3. Refining the properties of the EOS near the critical point gives ? = 5 in agreement with experimental results. We also discuss some scenarios for the EOS at finite temperatures.

SciTes
0
1009.1846 [abs pdf who comments(0)]
Title: The land of deformation south of $^{68}$Ni
Authors: Silvia Lenzi, Frédéric Nowacki, Alfredo Poves, Sieja Kamila

We study the development of collectivity in the neutron-rich nuclei around $N=40$, where experimental and theoretical evidences suggest a rapid shape change from the spherical to the rotational regime, in analogy to what happens at the {\it island of inversion} surrounding $^{31}$Na. Theoretical calculations are performed within the interacting shell model framework in a large valence space, based on a $^{48}$Ca core which encompasses the full $pf$ shell for the protons and the $0f_{5/2}$, $1p_{3/2}$, $1p_{1/2}$, $0g_{9/2}$ and $1d_{5/2}$ orbits for the neutrons. The effective interaction is based on a G-matrix obtained from a realistic nucleon-nucleon potential whose monopole part is corrected empirically to produce effective single particle energies compatible with the experimental data. We find a good agreement between the theoretical results and the available experimental data. We predict the onset of deformation at different neutron numbers for the various isotopic chains. The maximum collectivity occurs in the chromium isotopes, where the large deformation regime starts already at $N=38$. The shell evolution responsible for the observed shape changes is discussed in detail, in parallel to the situation in the $N=20$ region.

SciTes
0
1009.1847 [abs pdf who comments(0)]
Title: Translation of collision geometry fluctuations into momentum anisotropies in relativistic heavy-ion collisions
Authors: Guang-You Qin, Hannah Petersen, Steffen A. Bass, Berndt Müller

We develop a systematic framework for the study of the initial collision geometry fluctuations in relativistic heavy-ion collisions and investigate how they evolve through different stages of the fireball history and translate into final particle momentum anisotropies. We find in our event-by-event analysis that only the few lowest momentum anisotropy parameters survive after the hydrodynamical evolution of the system. The geometry of the produced medium is found to be affected by the pre-equilibrium evolution of the medium and the thermal smearing of the discretized event-by-event initial conditions, both of which tend to smear out the spatial anisotropies. We find such effects to be more prominent for higher moments than for lower moments. The correlations between odd and even spatial anisotropy parameters during the pre-equilibrium expansion are quantitatively studied and found to be small. Our study provides a theoretical foundation for the understanding of initial state fluctuations and the collective expansion dynamics in relativistic heavy-ion collisions.

SciTes
0
1009.1860 [abs pdf who comments(0)]
Title: Properties of the ground-state baryons in chiral perturbation theory
Authors: J. Martin-Camalich, L. S. Geng, M. J. Vicente Vacas

We review recent progress in the understanding of low-energy baryon structure by means of chiral perturbation theory. In particular, we discuss the application of this formalism to the description of various properties such as the baryon-octet magnetic moments, the electromagnetic structure of decuplet resonances and the hyperon vector coupling $f_1(0)$. Moreover, we present the results on the chiral extrapolation of recent lattice QCD results on the lowest-lying baryon masses and we predict the corresponding baryonic sigma-terms.

SciTes
0
1009.0739 [abs pdf who comments(0)] [CROSS LISTED]
Title: Meta-stable States in Quark-Gluon Plasma
Authors: Mridupawan Deka, Sanatan Digal, Ananta P. Mishra

We study the meta-stable states in high temperature phase of QCD characterised by nonzero expectation values for the imaginary part of the Polyakov loop. We consider $N_f= 2, 3$ dynamical staggered quarks, and carry out simulations at various values of the coupling $\beta$ to observe these states. In particular, we find the value of the coupling ($\beta_m$) above which the meta-stable states appear. The values of $\beta_m$ we get suggest that these states can not be accessible even at LHC.

2010-09-09 and older
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Recent Comments

1002.3824 wilson : In this paper Sedrakyan and Chubukov have finally resolved the long-standing issue about the origin of the pseudogap in cuprates. This study...

1007.1749 dabacon : Figures 3 and 4 are...interesting?

1005.5173 renner : To clarify in response to the above comment, our main result is that quantum theory cannot be *extended*. We consider an extension to a the...

1005.5173 peaches : I'm not sure that it's fair to say that this is is an extension of Bell's result in the general case because the main theorem relies on the ...

1005.4932 ayvlasov : I am not quite realizing, if it is necessary to make some comments, because most arguments already have been raised by few different people ...

1004.0411 sattath : Hi,

First thing: it's a very interesting and beautiful result.

Unfortunately, I didn't fully understand the soundness ...

1005.0411 plasky : Dear Dan,

Thank you for the nice resource paper on various mass profiles. Last year Chris Fluke and I published a paper explorin...

1004.5186 and78 : Nice results! It is not your goal but it'd be important to know how well it behaves on social networks.

1004.1645 ayvlasov : I think, Phys. Rev. A 63, 054302 (arXiv:quant-ph/0010071)
may be interesting ...

1005.0411 Zhao : Dear Dan,

Your two new paper on Astroph look very nice and I wish a recent paper of us be of interest to you.

We ...

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