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Sep 21, 2013
09/13

by
Dirk H. Rischke

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I review the extraction of kinetic and chemical freeze-out parameters from experimental data, with particular emphasis on the underlying assumptions and the validity of the conclusions.

Source: http://arxiv.org/abs/nucl-th/0104071v2

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Sep 22, 2013
09/13

by
Dirk H. Rischke

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I compute the gluon self-energy in a color superconductor with three flavors of massless quarks, where condensation of Cooper pairs breaks the color and flavor SU(3)_c x U(3)_V x U(3)_A symmetry of QCD to the diagonal subgroup SU(3)_{c+V}. At zero temperature, all eight electric gluons obtain a Debye screening mass, and all eight magnetic gluons a Meissner mass. The Debye as well as the Meissner masses are found to be equal for the different gluon colors. These masses determine the coefficients...

Source: http://arxiv.org/abs/nucl-th/0003063v1

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Sep 23, 2013
09/13

by
Dirk H. Rischke

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Hydrodynamics is applied to describe the dynamics of relativistic heavy-ion collisions. The focus of the present study is the influence of a possible (phase) transition to the quark-gluon plasma in the nuclear matter equation of state on collective observables, such as the lifetime of the system and the transverse directed flow of matter. It is shown that such a transition leads to a softening of the equation of state, and consequently to a time-delayed expansion which is in principle...

Source: http://arxiv.org/abs/nucl-th/9608024v1

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Sep 24, 2013
09/13

by
Dirk H. Rischke

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The energy and momentum dependence of the gluon self-energy is investigated in a color superconductor with two flavors of massless quarks. The presence of a color-superconducting quark-quark condensate modifies the gluon self-energy for energies which are of the order of the gap parameter. For gluon energies much larger than the gap, the self-energy assumes the form given by the standard hard-dense loop approximation. It is shown that this modification of the gluon self-energy does not affect...

Source: http://arxiv.org/abs/nucl-th/0103050v1

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Sep 17, 2013
09/13

by
Dirk H. Rischke

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Our current knowledge of the quark-gluon plasma in thermodynamical equilibrium is reviewed. The phase diagram of strongly interacting matter is discussed, with emphasis on the quark-hadron phase transition and the color-superconducting phases of quark matter. Lattice QCD results on the order of the phase transition, the thermodynamical functions, the heavy quark free energy, mesonic spectral functions, and recent results for nonzero quark chemical potential are presented. Analytic attempts to...

Source: http://arxiv.org/abs/nucl-th/0305030v2

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Sep 23, 2013
09/13

by
Dirk H. Rischke

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Using the influence functional formalism, classical equations of motion for the O(N) model are derived in the presence of a heat bath, in both the symmetric phase as well as the phase of spontaneously broken symmetry. The heat bath leads to dissipation and fluctuation terms in the classical equations of motion, which are explicitly computed to lowest order in perturbation theory. In the broken phase these terms are found to be large for the sigma field, even at zero temperature, due to the...

Source: http://arxiv.org/abs/nucl-th/9806045v1

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Sep 22, 2013
09/13

by
Dirk H. Rischke

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I compute the gluon self-energy in a color superconductor with two flavors of massless quarks, where condensation of Cooper pairs breaks SU(3)_c to SU(2)_c. At zero temperature, there is neither Debye screening nor a Meissner effect for the three gluons of the unbroken SU(2)_c subgroup. The remaining five gluons attain an electric as well as a magnetic mass. For temperatures approaching the critical temperature for the onset of color superconductivity, or for gluon momenta much larger than the...

Source: http://arxiv.org/abs/nucl-th/0001040v1

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Jun 27, 2018
06/18

by
Dirk H. Rischke; Francesco Sannino

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We investigate the thermodynamic properties of a novel class of gauge-Yukawa theories that have recently been shown to be completely asymptotically safe, because their short-distance behaviour is determined by the presence of an interacting fixed point. Not only do all the coupling constants freeze at a constant and calculable value in the ultraviolet, their values can even be made arbitrarily small for an appropriate choice of the ratio $N_c/N_f$ of fermion colours and flavours in the...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice, High Energy Physics - Theory

Source: http://arxiv.org/abs/1505.07828

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Jul 20, 2013
07/13

by
Barbara Betz; Dirk H. Rischke

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Hot and/or dense, normal-conducting systems of relativistic fermions exhibit a particular collective excitation, the so-called plasmino. We compute the one-loop self-energy, the dispersion relation and the spectral density for fermions interacting via attractive boson exchange. It is shown that plasminos also exist in superconductors.

Source: http://arxiv.org/abs/nucl-th/0609019v2

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50

Sep 19, 2013
09/13

by
Stefan Strüber; Dirk H. Rischke

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We consider vector and axialvector mesons in the framework of a gauged linear sigma model with chiral $U(N_f)_R \times U(N_f)_L$ symmetry. For $N_f=2$, we investigate the behavior of the chiral condensate and the meson masses as a function of temperature by solving a system of coupled Dyson-Schwinger equations derived via the 2PI formalism in double-bubble approximation. We find that the inclusion of vector and axialvector mesons tends to sharpen the chiral transition. Within our approximation...

Source: http://arxiv.org/abs/0708.2389v2

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55

Sep 21, 2013
09/13

by
H. Malekzadeh; Dirk H. Rischke

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We calculate the self-energies and the spectral densities of longitudinal and transverse gluons at zero temperature in color-superconducting quark matter in the color-flavor-locked (CFL) phase. We find a collective excitation, a plasmon, at energies smaller than two times the gap parameter and momenta smaller than about eight times the gap. The dispersion relation of this mode exhibits a minimum at some nonzero value of momentum, indicating a van Hove singularity.

Source: http://arxiv.org/abs/hep-ph/0602082v2

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Sep 18, 2013
09/13

by
H. Malekzadeh; Dirk H. Rischke

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We calculate the spectral densities of electric and magnetic gluons at zero temperature in color-superconducting quark matter in the color-flavor-locking (CFL) phase. We find a collective excitation, a plasmon, at energies smaller than two times the gap parameter and momenta smaller than about eight times the gap. The dispersion relation of this mode exhibits a minimum at some nonzero value of momentum, indicating a van Hove singularity.

Source: http://arxiv.org/abs/hep-ph/0611141v1

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64

Sep 18, 2013
09/13

by
Dirk H. Rischke; Miklos Gyulassy

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The hydrodynamic expansion of quark-gluon plasmas with spherical and longitudinally boost-invariant geometries is studied as a function of the initial energy density. The sensitivity of the collective flow pattern to uncertainties in the nuclear matter equation of state is explored. We concentrate on the effect of a possible finite width, $\Delta T \sim 0.1 T_c$, of the transition region between quark-gluon plasma and hadronic phase. Although slow deflagration solutions that act to stall the...

Source: http://arxiv.org/abs/nucl-th/9606039v1

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Sep 19, 2013
09/13

by
Werner Deinet; Dirk H. Rischke

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We consider a phase-space model for particle production in nuclear collisions. Once the multiplicities of the individual particle species are known, single-inclusive momentum spectra can be computed after making simplifying assumptions for the matrix element for multiparticle production. Comparison of the calculated spectra with data for pions and kaons from central Pb+Pb collisions at E_{Lab}=158 AGeV reveals a residual longitudinal phase-space dominance in the final state of the reaction. We...

Source: http://arxiv.org/abs/nucl-th/0507076v3

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120

Sep 18, 2013
09/13

by
Qun Wang; Dirk H. Rischke

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We consider color superconductivity with two flavors of massless quarks which form Cooper pairs with total spin zero. We solve the gap equation for the color-superconducting gap parameter to subleading order in the QCD coupling constant $g$ at zero temperature. At this order in $g$, there is also a previously neglected contribution from the real part of the quark self-energy to the gap equation. Including this contribution leads to a reduction of the color-superconducting gap parameter $\f_0$...

Source: http://arxiv.org/abs/nucl-th/0110016v1

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61

Sep 21, 2013
09/13

by
Azwinndini Muronga; Dirk H. Rischke

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Non-ideal fluid dynamics with cylindrical symmetry in transverse direction and longitudinal scaling flow is employed to simulate the space-time evolution of the quark-gluon plasma produced in heavy-ion collisions at RHIC energies. The dynamical expansion is studied as a function of initial energy density and initial time. A causal theory of dissipative fluid dynamics is used instead of the standard theories which are acausal. We compute the parton momentum spectra and HBT radii from...

Source: http://arxiv.org/abs/nucl-th/0407114v2

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70

Sep 18, 2013
09/13

by
H. Malekzadeh; Dirk H. Rischke

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The self-energies and the spectral densities of longitudinal and transverse gluons at zero temperature in the color-flavor-locked (CFL) phase are calculated. There appears a collective excitation, a light plasmon, at energies smaller than two times the gap parameter and momenta smaller than about eight times the gap. The minimum in the dispersion relation of this mode at some nonzero value of momentum corresponds to the van Hove singularity.

Source: http://arxiv.org/abs/hep-ph/0611140v1

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103

Sep 18, 2013
09/13

by
Dirk H. Rischke; Miklos Gyulassy

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The width $\Delta T$ of the deconfinement transition region is shown to influence strongly the flow structure in the (Landau-) hydrodynamical expansion of a quark-gluon plasma. For a sharp first order transition ($\Delta T=0$) the mixed phase is rather long-lived, with a lifetime that has a maximum when the initial energy density is at the phase boundary between mixed and pure quark-gluon matter. For increasing $\Delta T$, however, the lifetime decreases rapidly. Hadronic matter, however,...

Source: http://arxiv.org/abs/nucl-th/9509040v1

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33

Sep 22, 2013
09/13

by
Dirk H. Rischke; Miklos Gyulassy

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Correlators of magnetic and electric field energy density are investigated for SU($N_c$) gauge theory at high temperatures $T$. At separations $z\leq 2/T$ the correlators are shown to be dominated by a power--law behavior even for finite gluon screening masses. This continuum behavior is well approximated on current $4\times 16^3$--lattices in the perturbative limit and leads to a considerable overestimate of screening masses deduced from fitting the lattice correlators with conventional...

Source: http://arxiv.org/abs/nucl-th/9409006v1

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84

Jul 20, 2013
07/13

by
Si-xue Qin; Dirk H. Rischke

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The maximum entropy method is used to compute the quark spectral function at nonzero temperature. We solve the gap equation of quantum chromodynamics (QCD) self-consistently, employing a rainbow kernel which phenomenologically models results from Dyson-Schwinger equations (DSE) and lattice QCD. We use the criterion of positivity restoration of the spectral function as a signal for deconfinement. Our calculation indicates that the critical temperature of deconfinement $T_d$ is slightly smaller...

Source: http://arxiv.org/abs/1304.6547v1

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56

Sep 23, 2013
09/13

by
Dennis D. Dietrich; Dirk H. Rischke

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Considering cold, dense quark matter with two massless quark flavors, we demonstrate how, in a self-consistent calculation in the framework of QCD, the condensation of Cooper pairs induces a non-vanishing background color field. This background color field has precisely the right magnitude to cancel tadpole contributions and thus ensures overall color neutrality of the two-flavor color superconductor.

Source: http://arxiv.org/abs/nucl-th/0312044v1

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51

Sep 22, 2013
09/13

by
Dirk H. Rischke; Igor A. Shovkovy

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In a two-flavor color superconductor, the SU(3)_c gauge symmetry is spontaneously broken by diquark condensation. The Nambu-Goldstone excitations of the diquark condensate mix with the gluons associated with the broken generators of the original gauge group. It is shown how one can decouple these modes with a particular choice of 't Hooft gauge. We then explicitly compute the spectral density for transverse and longitudinal gluons of adjoint color 8. The Nambu-Goldstone excitations give rise to...

Source: http://arxiv.org/abs/nucl-th/0205080v2

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8.0

Jun 30, 2018
06/18

by
Si-xue Qin; Dirk H. Rischke

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We study vacuum masses of charmonia and the charm-quark diffusion coefficient in the quark-gluon plasma based on the spectral representation for meson correlators. To calculate the correlators, we solve the quark gap equation and the inhomogeneous Bethe-Salpeter equation in the rainbow-ladder approximation. It is found that the ground-state masses of charmonia in the pseudoscalar, scalar, and vector channels can be well described. For $1.5\,T_c

Topics: High Energy Physics - Phenomenology, High Energy Physics - Lattice, Nuclear Experiment, Nuclear...

Source: http://arxiv.org/abs/1403.3025

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44

Sep 22, 2013
09/13

by
Yuri V. Kovchegov; Dirk H. Rischke

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The classical Yang-Mills equations are solved perturbatively in covariant gauge for a collision of two ultrarelativistic nuclei. The nuclei are taken as ensembles of classical color charges on eikonal trajectories. The classical gluon field is computed in coordinate space up to cubic order in the coupling constant g. We construct the Feynman diagrams corresponding to this field and show the equivalence of the classical and diagrammatic approaches. An argument is given which demonstrates that at...

Source: http://arxiv.org/abs/hep-ph/9704201v1

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35

Sep 22, 2013
09/13

by
Stefan B. Ruester; Dirk H. Rischke

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We compare quark stars made of color-superconducting quark matter to normal-conducting quark stars. We focus on the most simple color-superconducting system, a two-flavor color superconductor, and employ the Nambu-Jona-Lasinio (NJL) model to compute the gap parameter and the equation of state. By varying the strength of the four-fermion coupling of the NJL model, we study the mass and the radius of the quark star as a function of the value of the gap parameter. If the coupling constant exceeds...

Source: http://arxiv.org/abs/nucl-th/0309022v2

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53

Sep 21, 2013
09/13

by
Robert D. Pisarski; Dirk H. Rischke

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We review how a classification into representations of color and flavor can be used to understand the possible patterns of symmetry breaking for color superconductivity in dense quark matter. In particular, we show how for three flavors, color-flavor locking is precisely analogous to the usual pattern of chiral symmetry breaking in the QCD vacuum.

Source: http://arxiv.org/abs/nucl-th/9907094v1

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48

Sep 20, 2013
09/13

by
Dirk Roeder; Joerg Ruppert; Dirk H. Rischke

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Chiral symmetry restoration at nonzero temperature is studied in the framework of the O(4) linear sigma model and the U(N_f)_r x U(N_f)_l linear sigma model with N_f=2,3, and 4 quark flavors. We investigate the temperature dependence of the masses of the scalar and pseudoscalar mesons, and the non-strange, strange, and charm condensates within the Hartree approximation as derived from the Cornwall-Jackiw-Tomboulis formalism. We find that the masses of the non-strange and strange mesons at...

Source: http://arxiv.org/abs/nucl-th/0301085v1

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5.0

Jun 29, 2018
06/18

by
Etele Molnár; Harri Niemi; Dirk H. Rischke

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In Moln\'ar et al. [Phys. Rev. D 93, 114025 (2016)] the equations of anisotropic dissipative fluid dynamics were obtained from the moments of the Boltzmann equation based on an expansion around an arbitrary anisotropic single-particle distribution function. In this paper we make a particular choice for this distribution function and consider the boost-invariant expansion of a fluid in one dimension. In order to close the conservation equations, we need to choose an additional moment of the...

Topics: Plasma Physics, High Energy Physics - Phenomenology, Fluid Dynamics, Physics, Nuclear Theory

Source: http://arxiv.org/abs/1606.09019

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34

Sep 22, 2013
09/13

by
Denis Parganlija; Francesco Giacosa; Dirk H. Rischke

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We calculate low-energy meson decay processes and pion-pion scattering lengths in a globally chirally invariant two-flavour linear sigma model exploring the quark content of the scalar mesons f(0)(600) and a(0)(980), as well as f(0)(1370) and a(0)(1450). To this end, we investigate which one of these sets of fields is more likely to contain quark-antiquark states.

Source: http://arxiv.org/abs/1004.4817v1

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Jun 28, 2018
06/18

by
Jürgen Eser; Mara Grahl; Dirk H. Rischke

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The transition in quantum chromodynamics (QCD) from hadronic matter to the quark-gluon plasma (QGP) at high temperatures and/or net-baryon densities is associated with the restoration of chiral symmetry and can be investigated in the laboratory via heavy-ion collisions. We study this chiral transition within the functional renormalization group (FRG) approach applied to the two-flavor version of the extended Linear Sigma Model (eLSM). The eLSM is an effective model for the strong interaction...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Theory

Source: http://arxiv.org/abs/1508.06928

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112

Jul 19, 2013
07/13

by
Tian Zhang; Tomas Brauner; Dirk H. Rischke

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We investigate the properties of hot and/or dense matter in QCD-like theories with quarks in a (pseudo)real representation of the gauge group using the Nambu-Jona-Lasinio model. The gauge dynamics is modeled using a simple lattice spin model with nearest-neighbor interactions. We first keep our discussion as general as possible, and only later focus on theories with adjoint quarks of two or three colors. Calculating the phase diagram in the plane of temperature and quark chemical potential, it...

Source: http://arxiv.org/abs/1005.2928v2

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7.0

Jun 30, 2018
06/18

by
Stanislaus Janowski; Francesco Giacosa; Dirk H. Rischke

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We study the three-flavor chirally and dilatation invariant extended Linear Sigma Model with (pseudo)scalar and (axial-)vector mesons as well as a scalar dilaton field whose excitations are interpreted as a glueball. The model successfully describes masses and decay widths of quark-antiquark mesons in the low-energy region up to 1.6 GeV. Here we study in detail the vacuum properties of the scalar-isoscalar channel and find that (i) a narrow glueball is only possible if the vacuum expectation...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1408.4921

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68

Sep 19, 2013
09/13

by
Andreas Schmitt; Qun Wang; Dirk H. Rischke

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We study color superconductivity with $N_f=1,2,$ and 3 massless flavors of quarks. We present a general formalism to derive and solve the gap equations for condensation in the even-parity channel. This formalism shows that the leading-order contribution to the gap equation is unique for all color superconductors studied here, and that differences arise solely at the subleading order. We discuss a simple method to compute subleading contributions from the integration over gluon momenta in the...

Source: http://arxiv.org/abs/nucl-th/0209050v1

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60

Sep 20, 2013
09/13

by
Andreas Schmitt; Qun Wang; Dirk H. Rischke

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It is shown that color-superconducting quark matter, where quarks of the same flavor form Cooper pairs with spin one, exhibits an electromagnetic Meissner effect. This is in contrast to spin-zero color superconductors where Cooper pairs consist of quarks with different flavors.

Source: http://arxiv.org/abs/nucl-th/0301090v3

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63

Sep 22, 2013
09/13

by
Denis Parganlija; Francesco Giacosa; Dirk H. Rischke

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We calculate low-energy meson decay processes and pion-pion scattering lengths in a two-flavour linear sigma model with global chiral symmetry, exploring the scenario in which the scalar mesons $f_0$(600) and $a_0$(980) are assumed to be $\bar q q$ states.

Source: http://arxiv.org/abs/0812.2183v1

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Jun 28, 2018
06/18

by
Adrian Koenigstein; Francesco Giacosa; Dirk H. Rischke

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In this paper, we review classical and quantum field theory of massive non-interacting spin-two fields. We derive the equations of motion and Fierz-Pauli constraints via three different methods: the eigenvalue equations for the Casimir invariants of the Poincar\'{e} group, a Lagrangian approach, and a covariant Hamilton formalism. We also present the conserved quantities, the solution of the equations of motion in terms of polarization tensors, and the tree-level propagator. We then discuss...

Topics: High Energy Physics - Phenomenology, High Energy Physics - Theory

Source: http://arxiv.org/abs/1508.00110

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61

Jul 20, 2013
07/13

by
Denis Parganlija; Francesco Giacosa; Dirk H. Rischke

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We calculate pion-pion scattering lengths and sigma, rho and a1 decay widths from a gauged linear sigma model with two flavours and its globally invariant generalisation.

Source: http://arxiv.org/abs/0804.3949v1

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Sep 18, 2013
09/13

by
Defu Hou; Qun Wang; Dirk H. Rischke

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We derive a generalized Ward identity for color-superconducting quark matter via the functional integral approach. The identity implies the gauge independence of the color-superconducting gap parameter on the quasi-particle mass shell to subleading order in covariant gauge.

Source: http://arxiv.org/abs/hep-ph/0401152v1

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Sep 22, 2013
09/13

by
Susanna Wilms; Francesco Giacosa; Dirk H. Rischke

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We compute pion-nucleon scattering at tree-level within a gauged linear sigma model which contains the nucleon and its chiral partner. Such an investigation in principle allows to make definite predictions as to whether the main contribution to the nucleon mass comes from the chiral condensate or from the mixing with its chiral partner. We find that there seems to be no set of model parameters that allows for a simultaneous description of all experimentally measured scattering lengths and range...

Source: http://arxiv.org/abs/nucl-th/0702076v1

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Jun 28, 2018
06/18

by
Zahra Ghalenovi; Francesco Giacosa; Dirk H. Rischke

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Scalar tetraquark states are studied within the diquark-antidiquark picture in a non-relativistic approach. We consider two types of confining potentials, a quadratic and a linear one, to which we also add spin-spin, isospin-isospin, and spin-isospin interactions. We calculate the masses of the scalar diquarks and of the ground-state open and hidden charmed and bottom scalar tetraquarks. Our results indicate that the scalar resonances $D_{0}^{\ast}(2400)$ and $D_{s}(2632)$ have a sizable...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1507.03345

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Sep 21, 2013
09/13

by
Susanna Gallas; Francesco Giacosa; Dirk H. Rischke

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We calculate the pion-nucleon scattering lengths $a_{0}^{(\pm)}$ and the mass parameter $m_{0}$, which describes the nucleon mass in the chiral limit, at tree-level in the framework of a globally symmetric linear sigma model with parity-doubled nucleons. When recent lattice results [Takahashi] are used, we obtain $m_{0}\simeq300-600$ MeV. While $a_{0}^{(-)}$ is in fair agreement with experimental data, $a_{0}^{(+)}$ is too small because of the employed large scalar meson mass. This indicates...

Source: http://arxiv.org/abs/0901.4043v1

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Sep 23, 2013
09/13

by
Giuseppe Colucci; Armen Sedrakian; Dirk H. Rischke

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We apply thermal field theory methods to compute microscopically the nucleon self-energy arising from one-pion exchange in isospin-symmetric nuclear matter and neutron matter. A self-consistent numerical scheme is introduced and its convergence is demonstrated. The repulsive contribution from the Fock exchange diagram to the energy per nucleon in symmetric nuclear matter is obtained.

Source: http://arxiv.org/abs/1303.1270v3

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Jun 30, 2018
06/18

by
Khaled Teilab; Francesco Giacosa; Dirk H. Rischke

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We study the production of non-strange mesons in proton-proton scattering reactions within an effective model of mesons and baryons with global chiral symmetry. The model includes the nucleon ($N$) and its chiral partner ($N^{\ast}$) and their couplings to the $N_{f}=2$ multiplets of (pseudo-)scalar and (axial-)vector mesons. Results for the production of $\omega$ and $\eta$ mesons are presented.

Topics: High Energy Physics - Phenomenology, Nuclear Theory

Source: http://arxiv.org/abs/1406.3504

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Sep 17, 2013
09/13

by
Denis Parganlija; Francesco Giacosa; Dirk H. Rischke

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We present a two-flavour linear sigma model with global chiral symmetry and vector and axial-vector mesons. We calculate pion-pion scattering lengths and the decay widths of scalar, vector, and axial-vector mesons. It is demonstrated that vector and axial-vector meson degrees of freedom play an important role in these low-energy processes and that a reasonable theoretical description requires globally chirally invariant terms other than the vector meson mass term. An important question for...

Source: http://arxiv.org/abs/1003.4934v1

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Jun 28, 2018
06/18

by
Thomas Wolkanowski; Francesco Giacosa; Dirk H. Rischke

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Light scalar hadrons can be understood as dynamically generated resonances. These arise as `companion poles' in the propagators of quark-antiquark seed states when accounting for meson-loop contributions to the self-energies of the latter. Along this line, we extend previous calculations of T\"ornqvist and Roos and of Boglione and Pennington, where the resonance $a_{0}(980)$ appears as companion pole in the propagator of $a_{0}(1450)$ which is predominantly a quark-antiquark state. We also...

Topic: High Energy Physics - Phenomenology

Source: http://arxiv.org/abs/1508.00372

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Sep 23, 2013
09/13

by
Achim Heinz; Francesco Giacosa; Dirk H. Rischke

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We study the large-N_c behavior of the critical temperature T_c for chiral symmetry restoration in the framework of the Nambu-Jona-Lasinio (NJL) model and the linear \sigma-model. While in the NJL case T_c scales as N_c^0 and is, as expected, of the same order as \Lambda_QCD (just as the deconfinement phase transition), in the \sigma-model the scaling behavior reads T_c \propto N_c^1/2. We investigate the origin of the different scaling behavior and present two improvements of the \sigma-model:...

Source: http://arxiv.org/abs/1110.1528v1

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48

Sep 21, 2013
09/13

by
Jin-cheng Wang; Qun Wang; Dirk H. Rischke

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We study the formation of baryons as composed of quarks and diquarks in hot and dense hadronic matter in a Nambu--Jona-Lasinio (NJL)--type model. We first solve the Dyson-Schwinger equation for the diquark propagator and then use this to solve the Dyson-Schwinger equation for the baryon propagator. We find that stable baryon resonances exist only in the phase of broken chiral symmetry. In the chirally symmetric phase, we do not find a pole in the baryon propagator. In the color-superconducting...

Source: http://arxiv.org/abs/1008.4029v3

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Sep 23, 2013
09/13

by
Miodrag L. Kulic; Armen Sedrakian; Dirk H. Rischke

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A rotating ultracold S-wave superfluid Fermi gas is considered, when the population imbalance (or equivalently the mismatch in chemical potentials) corresponds to the Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) state in the vicinity of the Lifshitz critical point. It is shown that under these conditions the critical angular velocity in two-dimensional systems is an oscillating function of temperature and population imbalance giving rise to reentrant superfluid phases. This leads to vortex lattices...

Source: http://arxiv.org/abs/0904.4034v1

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54

Sep 21, 2013
09/13

by
Masakiyo Kitazawa; Dirk H. Rischke; Igor A. Shovkovy

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We explore the formation of diquark molecules and their Bose-Einstein condensation (BEC) in the phase diagram of three-flavor quark matter at nonzero temperature, T, and quark chemical potential, mu. Using a quark model with a four-fermion interaction, we identify possible diquark excitations as poles of the microscopically computed diquark propagator. The quark masses are obtained by solving a dynamical equation for the chiral condensate and are found to determine the stability of the diquark...

Source: http://arxiv.org/abs/0709.2235v1

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7.0

Jun 30, 2018
06/18

by
Walaa I. Eshraim; Francesco Giacosa; Dirk H. Rischke

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We study the so-called extended linear sigma model for the case of four quark flavors. This model is based on global chiral symmetry and dilatation invariance and includes, besides scalar and pseudoscalar mesons, vector and axial-vector mesons. Most of the parameters of the model have been determined in previous work by fitting properties of mesons with three quark flavors. Only three new parameters, all related to the current charm quark mass, appear when introducing charmed mesons....

Topics: High Energy Physics - Phenomenology, Nuclear Theory

Source: http://arxiv.org/abs/1405.5861