Wed·Aug 19, 2015Wednesday·August 19, 2015

1. 01*

   Semiclassical solution to the BFKL equation with massive gluons

   Eugene Levin🇮🇱 · Lev Lipatov🇷🇺 · M. Siddikov🇨🇱

   In this paper we proceed to study the high energy behavior of a scattering amplitudes in the Yang-Mills theory with the Higgs mechanism for the gauge boson mass. The spectrum of the $j$-plane singularities of the $t$-channel partial waves, and corresponding eigenfunctions of the BFKL equation in leading log approximation (LLA), were previously calculated by us numerically in arXiv:1401.4671 . Here we develop a semiclassical approach and investigate the influence of the impact parameter exponential decrease, existing in this model, on the high energy asymptotic behaviour of the scattering amplitude. This approach is much simpler than the numerical calculations, and reproduces our earlier numerical results. The analytical (semianalytical) solutions which have been found in this paper, can be used to incorporate correctly the large impact parameter behavior in the framework of CGC/saturation approach. This behaviour is interesting as provides the high energy amplitude for the electroweak theory, which can be measured experimentally.

   hep-phEPJC(2015)·9 citations
2. 02*

   Radiatively-induced gravitational leptogenesis

   J. I. McDonald🇬🇧 · G. M. Shore🇬🇧

   We demonstrate how loop effects in gravitational backgrounds lead to a difference in the propagation of matter and antimatter, and show this is forbidden in flat space due to CPT and translation invariance. This mechanism, which is naturally present in beyond the standard model (BSM) theories exhibiting C and CP violation, generates a curvature-dependent chemical potential for leptons in the low-energy effective Lagrangian, allowing a matter-antimatter asymmetry to be generated in thermodynamic equilibrium, below the BSM scale.

   hep-phhep-thPLB(2015)·19 citations
3. 03*

   Right-handed neutrinos and the 2 TeV $W^{\prime }$ boson

   Pilar Coloma🇺🇸 · Bogdan A. Dobrescu🇺🇸 · Jacobo Lopez-Pavon🇮🇹

   The CMS $e^{+}{e}^{-}jj$ events of invariant mass near 2 TeV are consistent with a $W^{\prime }$ boson decaying into an electron and a right-handed neutrino whose TeV-scale mass is of the Dirac type. We show that the Dirac partner of the right-handed electron-neutrino can be the right-handed tau-neutrino. A prediction of this model is that the sum of the ${\tau }^{+}{e}^{+}jj$ and ${\tau }^{-}{e}^{-}jj$ signal cross sections equals twice that for $e^{+}{e}^{-}jj$. The Standard Model neutrinos acquire Majorana masses and mixings compatible with neutrino oscillation data.

   hep-phhep-exPRD(2015)·43 citations
4. 04*

   Non-perturbative over-production of axion-like-particles (ALPs) via derivative interaction

   Anupam Mazumdar🇬🇧 · Saleh Qutub🇸🇦

   Axion like particles (ALPs) are quite generic in many scenarios for physics beyond the Standard Model, they are pseudoscalar Nambu-Goldstone bosons, and appear once any global $U(1)$ symmetry is broken spontaneously. The ALPs can gain mass from various non-perturbative quantum effects, such as anomalies or instantons. ALPs can couple to the matter sector incluidng a scalar condensate such as inflaton or moduli field via derivative interactions, which are suppressed by the axion {\it decay constant}, $f_{\chi }$ . Although weakly interacting, the ALPs can be produced abundantly from the coherent oscillations of a homogeneous condensate. In this paper we will study such a scenario where the ALPs can be produced abundantly, and in some cases can even overclose the Universe via odd and even dimensional operators, as long as $f_{\chi }/{\Phi }_{\mathrm{I}}\ll 1$, where ${\Phi }_{\mathrm{I}}$ denotes the initial amplitude of the coherent oscillations of the scalar condensate, $\varphi$. We will briefly mention how such dangerous overproduction would affect dark matter and dark radiation abundances in the Universe.

   hep-phastro-ph.COhep-thPRD(2016)·13 citations
5. 05*

   Hard Matching for Boosted Tops at Two Loops

   Andre H. Hoang🇦🇹 · Aditya Pathak🇺🇸 · Piotr Pietrulewicz🇩🇪 · Iain W. Stewart🇺🇸

   Cross sections for top quarks provide very interesting physics opportunities, being both sensitive to new physics and also perturbatively tractable due to the large top quark mass. Rigorous factorization theorems for top cross sections can be derived in several kinematic scenarios, including the boosted regime in the peak region that we consider here. In the context of the corresponding factorization theorem for $e^{+}{e}^{-}$ collisions we extract the last missing ingredient that is needed to evaluate the cross section differential in the jet-mass at two-loop order, namely the matching coefficient at the scale $\mu \simeq m_t$. Our extraction also yields the final ingredients needed to carry out logarithmic resummation at next-to-next-to-leading logarithmic order (or N${}^3$LL if we ignore the missing 4-loop cusp anomalous dimension). This coefficient exhibits an amplitude level rapidity logarithm starting at $\mathcal{O}({\alpha }_s^2)$ due to virtual top quark loops, which we treat using rapidity renormalization group (RG) evolution. Interestingly, this rapidity RG evolution appears in the matching coefficient between two effective theories around the heavy quark mass scale $\mu \simeq m_t$.

   hep-phnucl-thJHEP(2015)·52 citations
6. 06*

   Flavored gauge mediation in the Peccei-Quinn NMSSM

   Kamila Kowalska🇵🇱 · Jacek Pawelczyk🇵🇱 · Enrico Maria Sessolo🇵🇱

   We investigate a particular version of the Peccei-Quinn (PQ) NMSSM characterized by an economical and rigidly hierarchical flavor structure and based on flavored gauge mediation and on some considerations inspired by string theory GUTs. In this way we can express the Lagrangian of the PQ NMSSM through very few parameters. The obtained model is studied numerically and confronted with the most relevant phenomenological constraints. We show that typical spectra are for the most part too heavy to be significantly probed at the LHC, but regions of the parameter space exist yielding signatures that might possibly be observed during Run II. We also calculate the fine tuning of the model. We show that, in spite of the appearance of large scales in the superpotential and soft terms, it does not exceed the tuning present in the MSSM for equivalent spectra, which is of the order of 10^4.

   hep-phJHEP(2015)·2 citations
7. 07*

   Moduli induced cogenesis of baryon asymmetry and dark matter

   Mansi Dhuria🇮🇳 · Chandan Hati🇮🇳 · Utpal Sarkar🇮🇳

   We study a cogenesis mechanism in which the observed baryon asymmetry of the universe and the dark matter abundance can be produced simultaneously at low reheating temperature without violating baryon number in the fundamental vertex. In particular, we consider a model which could be realized in the context of type IIB large volume string compactifications. The matter superfields in this model include additional pairs of color triplet and singlet superfields in addition to the Minimal Supersymmetric Standard Model (MSSM) superfields. Assuming that the mass of the additional singlet fermions is O(GeV) and color triplet fermions is O(TeV), we show that the modulus dominantly decays into the additional color triplet superfields. After soft supersymmetry (SUSY) breaking, the lightest eigenstate of scalar component of color triplet superfield further decays into fermionic component of singlet superfield and quarks without violating baryon number. Assuming R-parity conservation, it follows that the singlet superfield will not further decay into the SM particles and therefore it can be considered as a stable asymmetric dark matter (ADM) component. We find that the decay of the lightest eigenstate of scalar component of color triplet superfield gives the observed baryon asymmetry in the visible sector, an asymmetric dark matter component with the right abundance and naturally explains cosmic coincidence.

   hep-phhep-thPLB(2016)·18 citations
8. 08*

   Augmenting the diboson excess for Run 2

   Dorival Goncalves🇬🇧 · Frank Krauss🇬🇧 · Michael Spannowsky🇬🇧

   The ATLAS collaboration recently reported an excess of events in the high invariant mass tail of reconstructed di-boson events. We investigate their analysis and point to possible subtleties and improvements in the jet substructure implementation and data-driven background estimates.

   hep-phPRD(2015)·27 citations
9. 09*

   Decays $Z\to \gamma \gamma$ and $Z\to gg$ in the Standard Model Extension

   J. Castro-Medina🇲🇽 · H. Novales-Sánchez🇲🇽 · J. J. Toscano🇲🇽 · E. S. Tututi🇲🇽

   The $Z\to \gamma \gamma$ and $Z\to gg$ decays are studied in the context of the renormalizable version of the Standard Model Extension. The $CPT$-odd $\bar{\psi }{\gamma }_5{\gamma }^{\mu }{b}_{\mu }\psi$ bilinear interaction, which involves the constant background field $b_{\alpha }$ and which has been a subject of interest in literature, is considered. It is shown that the $Z\to \gamma \gamma$ and $Z\to gg$ decays, which are strictly zero in the standard model, can be generated radiatively at the one-loop level. It is found that these decays are gauge invariant and free of ultraviolet divergences, and that the corresponding decay widths only depend on the spatial component of the background field $b$.

   hep-phInt.J.Mod.Phys.A(2015)·10 citations
10. 10*

    Strong Coupling Running, Gauge Coupling Unification and the Scale of New Physics

    Dimitri Bourilkov🇺🇸

    The apparent unification of gauge couplings in Grand Unified Theories around 10${}^{16}$ GeV is one of the strong arguments in favor of Supersymmetric extensions of the Standard Model. In this paper, an analysis of the measurements of the strong coupling running from the CMS experiment at the LHC is combined with a "traditional" gauge coupling unification analysis using data at the Z peak. This approach places powerful constraints on the possible scales of new physics and on the parameters around the unification scale. A supersymmetric analysis without GUT threshold corrections describes the CMS data well and provides perfect unification. The favored scales are $M_{SUSY}=2820+670-540$ GeV and $M_{GUT}=1.05\pm 0.06\cdot 10^{16}$ GeV. For zero or small threshold corrections the scale of new physics may be well within LHC reach.

    hep-phhep-exJHEP(2015)·11 citations
11. 11*

    Analysis of the ${\frac{1}{2}}^{\pm }$ pentaquark states in the diquark model with QCD sum rules

    Zhi-Gang Wang🇨🇳 · Tao Huang🇨🇳

    In this article, we present the scalar-diquark-scalar-diquark-antiquark type and scalar-diquark-axialvector-diquark-antiquark type pentaquark configurations in the diquark model, and study the masses and pole residues of the $J^P={\frac{1}{2}}^{\pm }$ hidden-charmed pentaquark states in details with the QCD sum rules by extending our previous work on the $J^P={\frac{3}{2}}^{-}$ and ${\frac{5}{2}}^{+}$ hidden-charmed pentaquark states. We calculate the contributions of the vacuum condensates up to dimension-10 in the operator product expansion by constructing both the scalar-diquark-scalar-diquark-antiquark type and scalar-diquark-axialvector-diquark-antiquark type interpolating currents. The present predictions of the masses can be confronted to the LHCb experimental data in the future.

    hep-phEPJC(2016)·105 citations
12. 12*

    Short-range two-particle correlations from statistical clusters

    Andrzej Bialas🇵🇱 · Adam Bzdak🇵🇱

    The two-particle short-range correlation functions in rapidity, azimuthal angle and transverse momentum, following from the decay of statistical clusters are evaluated and discussed.

    hep-phhep-exPRD(2016)·5 citations
13. 13*

    CGC/saturation approach for soft interactions at high energy: long range rapidity correlations

    E. Gotsman (Tel Aviv U.)🇮🇱 · E. Levin (Tel Aviv U./UTFSM)🇮🇱 · U. Maor (Tel Aviv U.)🇮🇱

    In this paper we continue our program to build a model for high energy soft interactions, that is based on the CGC/saturation approach.The main result of this paper is that we have discovered a mechanism that leads to large long range rapidity correlations, and results in large values of the correlation function $R\text{Lb}{y}_1,y_2\text{Rb}\ge 1$, which is independent of $y_1$ and $y_2$. Such behaviour of the correlation function, provides strong support for the idea, that at high energies the system of partons that is produced, is not only dense, but also has strong attractive forces acting between the partons.

    hep-phEPJC(2015)·15 citations
14. 14*

    Spin Physics and Transverse Structure

    P.J. Mulders🇳🇱

    Spin is a welcome complication in the study of partonic structure that has led to new insights, even if theoretically and experimentally not all dust has settled, in particular on quark flavor dependence and gluon spin. At the same time it opened new questions on angular momentum and effects of transverse structure. In this talk the focus is on the role of the transverse momenta of partons. Like for collinear parton distribution functions (PDFs), we are also in the case of transverse momentum dependent (TMD) PDFs, talking about forward matrix elements. TMD PDFs (or in short TMDs) extend collinear PDFs with only spin-spin correlations to PDFs that include spin-momentum correlations, including also time-reversal-odd (T-odd) correlations, relevant for the description of single spin asymmetries. In this way TMDs open up new ways of studying the spin structure. Their operator structure within QCD, however, is more complex leading to various ways of breaking of universality.

    hep-phPoS(2015)·2 citations
15. 15*

    Analysis of exclusive $k_T$ jet algorithms in electron-positron annihilation

    Junegone Chay🇰🇷 · Chul Kim🇰🇷 · Inchol Kim🇰🇷

    We study the factorization of the dijet cross section in $e^{+}{e}^{-}$ annihilation using the generalized exclusive jet algorithm which includes the cone-type, the JADE, the $k_T$, the anti-$k_T$ and the Cambridge/Aachen jet algorithms as special cases. In order to probe the characteristics of the jet algorithms in a unified way, we consider the generalized $k_T$ jet algorithm with an arbitrary weight of the energies, in which various types of the $k_T$-type algorithms are included for specific values of the parameter. We show that the jet algorithm respects the factorization property for the parameter $\alpha <2$. The factorized jet function and the soft function are well defined and infrared safe for all the jet algorithms except the $k_T$ algorithm. The $k_T$ algorithm ($\alpha =2$) breaks the factorization since the jet and the soft functions are infrared divergent and are not defined for $\alpha =2$, though the dijet cross section is infrared finite. In the jet algorithms which enable factorization, we give a phenomenological analysis using the resummed and the fixed-order results.

    hep-phPRD(2015)·3 citations
16. 16*

    The Framed Standard Model (II) - A first Test against Experiment

    HM Chan (Rutherford Appleton Laboratory) · ST Tsou (Mathematical Institute, Oxford University)

    Apart from the qualitative features described in \cite{chm}, the renormalization group equation derived for the rotation of the fermion mass matrices are amenable to quantitative study. The equation depends on a coupling and a fudge factor and, on integration, on 3 integration constants. Its application to data analysis, however, requires the input from experiment of the heaviest generation masses $m_t,m_b,m_{\tau },m_{{\nu }_3}$ all of which are known, except for $m_{{\nu }_3}$. Together then with the theta-angle in the QCD action, there are in all 7 real unknown parameters. Determining these 7 parameters by fitting to the experimental values of the masses $m_c,m_{\mu },m_e$, the CKM elements $|V_{us}|,|V_{ub}|$, and the neutrino oscillation angle ${\sin }^2{\theta }_{13}$, one can then calculate and compare with experiment the following 12 other quantities $m_s,m_u/m_d,|V_{ud}|,|V_{cs}|,|V_{tb}|,|V_{cd}|,|V_{cb}|,|V_{ts}|,|V_{td}|,J,{\sin }^{2}2{\theta }_{12},{\sin }^{2}2{\theta }_{23}$, and the results all agree reasonably well with data, often to within the stringent experimental error now achieved. Counting the predictions not yet measured by experiment, this means that 17 independent parameters of the standard model are now replaced by 7 in the FSM.

    hep-phInt.J.Mod.Phys.A(2015)·3 citations
17. 17*

    Vector meson spectral function and dilepton rate in an effective mean field model

    Chowdhury Aminul Islam🇮🇳 · Sarbani Majumder🇮🇳 · Najmul Haque🇺🇸 · Munshi G. Mustafa🇮🇳

    We have studied the vector meson spectral function (VMSF) in a hot and dense medium within an effective QCD model namely the Nambu-Jona-Lasinio (NJL) and its Polyakov Loop extended version (PNJL) with and without the effect of isoscalar vector interaction (IVI). The effect of the IVI has been taken into account using the ring approximation. We obtained the dilepton production rate (DPR) using the VMSF and observed that at moderate temperature it is enhanced in the PNJL model as compared to the NJL and Born rate due to the suppression of color degrees of freedom.

    hep-phnucl-thSpringer Proc.Phys.(2016)·0 citations
18. 18*

    Three-loop HTLpt thermodynamics at finite temperature and chemical potential

    Aritra Bandyopadhyay🇮🇳 · Najmul Haque🇺🇸 · Munshi G. Mustafa🇮🇳 · Michael Strickland🇺🇸 · Nan Su🇩🇪

    In this proceedings we present a state-of-the-art method of calculating thermodynamic potential at finite temperature and finite chemical potential, using Hard Thermal Loop perturbation theory (HTLpt) up to next-to-next-leading-order (NNLO). The resulting thermodynamic potential enables us to evaluate different thermodynamic quantities including pressure and various quark number susceptibilities (QNS). Comparison between our analytic results for those thermodynamic quantities with the available lattice data shows a good agreement.

    hep-phnucl-thSpringer Proc.Phys.(2016)·0 citations
19. 19*

    Quark model with chiral-symmetry breaking and confinement in the Covariant Spectator Theory

    Elmar P. Biernat🇵🇹 · M. T. Peña🇵🇹 · J. E. Ribeiro🇵🇹 · A. Stadler🇵🇹 · F. Gross🇺🇸

    We propose a model for the quark-antiquark interaction in Minkowski space using the Covariant Spectator Theory. We show that with an equal-weighted scalar-pseudoscalar structure for the confining part of our interaction kernel the axial-vector Ward-Takahashi identity is preserved and our model complies with the Adler-zero constraint for pi-pi-scattering imposed by chiral symmetry.

    hep-phnucl-thEPJ Web Conf.(2016)·1 citation
20. 20*

    Variable Flavor Number Scheme for Final State Jets in DIS

    Andre H. Hoang🇦🇹 · Piotr Pietrulewicz🇩🇪 · Daniel Samitz🇦🇹

    We discuss massive quark effects in the endpoint region $x\to 1$ of inclusive deep inelastic scattering, where the hadronic final state is collimated and thus represents a jet. In this regime heavy quark pairs are generated via secondary radiation, i.e. due to a gluon splitting in light quark initiated contributions starting at $\mathcal{O}({\alpha }_s^2)$ in the fixed-order expansion. Based on the factorization framework for massless quarks in Soft Collinear Effective Theory (SCET), we construct a variable flavor number scheme that deals with arbitrary hierarchies between the mass scale and the kinematic scales exhibiting a continuous behavior between the massless limit for very light quarks and the decoupling limit for very heavy quarks. We show that the threshold matching corrections for all gauge invariant components at the mass scale are related to each other via consistency conditions. This is explicitly demonstrated by recalculating the known threshold correction for the parton distribution function at $\mathcal{O}({\alpha }_s^2{C}_F{T}_F)$ within SCET. The latter contains large rapidity logarithms $\sim \ln (1-x)$ that can be summed by exponentiation. Their coefficients are universal which can be used to obtain potentially relevant higher order results for generic threshold corrections at colliders from computations in deep inelastic scattering. In particular, we extract the $\mathcal{O}({\alpha }_s^3)$ threshold correction multiplied by a single rapidity logarithm from results obtained earlier.

    hep-phPRD(2016)·24 citations
21. 21*

    Gluino LOSP with Axino LSP

    Stuart Raby🇺🇸

    In this letter we have presented a novel version of "long-lived" gluinos in supersymmetric models with the gluino the lightest ordinary supersymmetric particle [LOSP] and axino LSP. Within certain ranges of the axion decay constant $f_a<1\times 10^{10}$ GeV, the gluino mass bounds are reduced to less than 1000 GeV. The best limits can be obtained by looking for decaying R-hadrons in the detector where the gluino decays to a gluon and axino in the calorimeters. SUSY models with a gluino LOSP can occur over a significant region of parameter space in either {\em mirage-mediation} or general gauge-mediated SUSY breaking models. The gluino LOSP is not constrained by cosmology, but in this scenario the axion/axino may be good dark matter candidates.

    hep-phPRL(2015)·3 citations
22. 22*

    Non-Simplified SUSY: Stau-Coannihilation at LHC and ILC

    M. Berggren (1)🇩🇪 · A. Cakir (1,2)🇹🇷 · D. Krücker (1)🇩🇪 · J. List (1)🇩🇪 · I. A. Melzer-Pellmann (1)🇩🇪 · B. Safarzadeh Samani (1,3)🇩🇪 · C. Seitz (1)🇩🇪 · S. Wayand (4) ((1) DESY, Hamburg, Germany, (2) Istanbul Technical University, Turkey, (3) IPM, Tehran, Iran, (4) KIT IEKP, Karlsruhe, Germany)🇩🇪

    If new phenomena beyond the Standard Model will be discovered at the LHC, the properties of the new particles could be determined with data from the High-Luminosity LHC and from a future linear collider like the ILC. We discuss the possible interplay between measurements at the two accelerators in a concrete example, namely a full SUSY model which features a small stau_1-LSP mass difference. Various channels have been studied using the Snowmass 2013 combined LHC detector implementation in the Delphes simulation package, as well as simulations of the ILD detector concept from the Technical Design Report. We investigate both the LHC and ILC capabilities for discovery, separation and identification of various parts of the spectrum. While some parts would be discovered at the LHC, there is substantial room for further discoveries at the ILC. We finally highlight examples where the precise knowledge about the lower part of the mass spectrum which could be acquired at the ILC would enable a more in-depth analysis of the LHC data with respect to the heavier states.

    hep-phhep-exEPJC(2016)·34 citations
23. 23*

    Finite Volume Corrections to the Electromagnetic Mass of Composite Particles

    Jong-Wan Lee🇺🇸 · Brian C. Tiburzi🇺🇸

    The long-range electromagnetic interaction presents a challenge for numerical computations in QCD + QED. In addition to power-law finite volume effects, the standard lattice gauge theory approach introduces non-locality through removal of photon zero-momentum modes. The resulting finite volume effects must be quantitatively understood; and, to this end, non-relativistic effective field theories are an efficient tool, especially in the case of composite particles. Recently an oddity related to non-locality of the standard lattice approach was uncovered by the Budapest-Marseille-Wuppertal collaboration. Explicit contributions from antiparticles appear to be required so that finite volume QED results for a point-like fermion can be reproduced in the effective field theory description. We provide transparency for this argument by considering point-like scalars and spinors in finite volume QED using the method of regions. For the more germane case of composite particles, we determine that antiparticle modes contribute to the finite-volume electromagnetic mass of composite spinors through terms proportional to the squares of time-like form factors evaluated at threshold. We extend existing finite volume calculations to one order higher, which is particularly relevant for the electromagnetic mass of light nuclei. Additionally, we verify that the analogous finite volume contributions to the nucleon mass in chiral perturbation theory vanish in accordance with locality.

    ↳ hep-lathep-phnucl-thPRD(2016)·15 citations
24. 24*

    Dark Matter Annihilation and Decay Searches with the High Altitude Water Cherenkov (HAWC) Observatory

    J. Patrick Harding🇺🇸 · Brenda Dingus (for the HAWC Collaboration)🇺🇸

    In order to observe annihilation and decay of dark matter, several types of potential sources should be considered. Some sources, such as dwarf galaxies, are expected to have very low astrophysical backgrounds but fairly small dark matter densities. Other sources, like the Galactic center, are expected to have larger densities of dark matter but also have more complicated backgrounds from other astrophysical sources. To search for signatures of dark matter, the large field-of-view of the HAWC detector, covering 2 sr at a time, especially enables searches from sources of dark matter annihilation and decay, which are extended over several degrees on the sky. With a sensitivity over 2/3 of the sky, HAWC has the ability to probe a large fraction of the sky for the signals of TeV-mass dark matter. In particular, HAWC should be the most sensitive experiment to signals coming from dark matter with masses greater than 10-100 TeV. We present the HAWC sensitivity to annihilating and decaying dark matter signals for several likely sources of these signals.

    ↳ astro-ph.HEastro-ph.COhep-phPoS(2016)·24 citations
25. 25*

    Inhomogeneous chiral symmetry breaking in dense neutron-star matter

    Michael Buballa🇩🇪 · Stefano Carignano🇩🇪

    An increasing number of model results suggests that chiral symmetry is broken inhomogeneously in a certain window at intermediate densities in the QCD phase diagram. This could have significant effects on the properties of compact stars, possibly leading to new astrophysical signatures. In this contribution we discuss this idea by reviewing recent results on inhomogeneous chiral symmetry breaking under an astrophysics-oriented perspective. After introducing two commonly studied spatial modulations of the chiral condensate, the chiral density wave and the real kink crystal, we focus on their properties and their effect on the equation of state of quark matter. We also describe how these crystalline phases are affected by different elements which are required for a realistic description of a compact star, such as charge neutrality, the presence of magnetic fields, vector interactions and the interplay with color-superconductivity. Finally, we discuss possible signatures of inhomogeneous chiral symmetry breaking in the core of compact stars, considering the cases of mass-radius relations and neutrino emissivity explicitly.

    ↳ nucl-thastro-ph.HEhep-phEPJA(2016)·50 citations
26. 26*

    Deviations of the Energy-Momentum Tensor from Equilibrium in the Initial State for Hydrodynamics from Transport Approaches

    Dmytro Oliinychenko🇺🇦 · Hannah Petersen🇩🇪

    Many hybrid models of heavy ion collisions construct the initial state for hydrodynamics from transport models. Hydrodynamics requires that the energy-momentum tensor $T^{\mu \nu }$ and four-currents $j^{\mu }$ do not deviate considerably from the equilibrium ideal-fluid form, but the ones constructed from transport do not necessarily possess this property. In this work we investigate the space-time picture of $T^{\mu \nu }$ deviations from equilibrium in Au+Au collisions using a coarse-grained transport approach. The collision energy is varied in the range $E_{lab}=5-160A$ GeV. The sensitivity of $T^{\mu \nu }$ deviations from equilibrium to collision centrality, and other parameters such as the switching criterion, the amount of statistics used to construct the initial state, and the smearing parameter $\sigma$ is investigated. For low statistics deviations of $T^{\mu \nu }$ from equilibrium are large and dominated by the effect of finite sampling. For large statistics the pressure anisotropy plays the most significant role, while the off-diagonal components of $T^{\mu \nu }$ are small in a large volume during the whole evolution. For all considered energies and centralities the pressure anisotropy exhibits a similar feature: there is a narrow interval of time, when it rapidly drops in a considerable volume. This allows us to introduce an "isotropization time," which is found to decrease with energy and slightly increase with centrality. The isotropization times are larger than times typically used for initializing hydrodynamics.

    ↳ nucl-thhep-phPRC(2016)·57 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.