Fri·Nov 24, 2017Friday·November 24, 2017

1. 01*

   Collectivity in small systems - Initial state vs. final state effects

   Moritz Greif🇩🇪 · Carsten Greiner🇩🇪 · Björn Schenke🇺🇸 · Sören Schlichting🇺🇸 · Zhe Xu🇨🇳

   Observations of long rang azimuthal correlations in small collision systems (p+p/A) have triggered an enormous excitement in the heavy-ion community. However, it is presently unclear to what extent the experimentally observed correlations should be attributed to initial state momentum correlations and/or the final state response to the initial state geometry. We discuss how a consistent theoretical description of the non-equilibrium dynamics is important to address both effects within a unified framework and present first results from weakly coupled non-equilibrium simulations in \cite{Greif:2017bnr} to quantify the relative importance of initial state and final state effects based on theoretical calculations.

   hep-phnucl-thEPJ Web Conf.(2018)·1 citation
2. 02*

   Crystalline phases by an improved gradient expansion technique

   Stefano Carignano🇮🇹 · Filippo Anzuini🇮🇹 · Omar Benhar🇮🇹 · Massimo Mannarelli🇮🇹

   We develop an innovative technique for studying inhomogeneous phases with a spontaneous broken symmetry. The method relies on the knowledge of the exact form of the free energy in the homogeneous phase and on a specific gradient expansion of the order parameter. We apply this method to quark matter at vanishing temperature and large chemical potential, which is expected to be relevant for astrophysical considerations. The method is remarkably reliable and fast as compared to performing the full numerical diagonalization of the quark Hamiltonian in momentum space, and is designed to improve the standard Ginzburg-Landau expansion close to the phase transition points. For definiteness we focus on inhomogeneous chiral symmetry breaking, accurately reproducing known results for 1D and 2D modulations and examining novel crystalline structures, as well. Consistently with previous results, we find that the energetically favored modulation is the so-called 1D real kink crystal. We propose a qualitative description of the pairing mechanism to motivate this result.

   hep-phPRD(2018)·25 citations
3. 03*

   D meson production asymmetry, unfavoured fragmentation and consequences for prompt atmospheric neutrino production

   Rafal Maciula🇵🇱 · Antoni Szczurek🇵🇱

   We consider unfavoured light quark/antiquark to $D$ meson fragmentation. We discuss nonperturbative effects for small transverse momenta. The asymmetry for $D^{+}$ and $D^{-}$ production measured by the LHCb collaboration provides natural constraints on the parton (quark/antiquark) fragmentation functions. We find that already a fraction of $q/\bar{q}\to D$ fragmentation probability is sufficient to account for the measured asymmetry. We make predictions for similar asymmetry for neutral $D$ mesons. Large $D$-meson production asymmetries are found for large $x_F$ which is related to dominance of light quark/antiquark $q/\bar{q}\to D$ fragmentation over the standard $c\to D$ fragmentation. As a consequence, prompt atmospheric neutrino flux at high neutrino energies can be much larger than for the conventional $c\to D$ fragmentation. The latter can constitute a sizeable background for the cosmic neutrinos claimed to be observed recently by the IceCube Observatory. Large rapidity-dependent $D^{+}/D^{-}$ and $D^0/{\bar{D}}^0$ asymmetries are predicted for low ($\sqrt{s}=$ 20 - 100 GeV) energies. The $q/\bar{q}\to D$ fragmentation leads to enhanced production of $D$ mesons at low energies. At $\sqrt{s}$ = 20 GeV the enhancement factor with respect to the conventional contribution is larger than a factor of five. In the considered picture the large-$x_F$ $D$ mesons are produced dominantly via fragmentation of light quarks/antiquarks. Predictions for fixed target $p{+}^4\text{He}$ collisions relevant for a fixed target LHCb experiment are presented.

   hep-phhep-exPRD(2018)·18 citations
4. 04*

   On Minimal Dark Matter coupled to the Higgs

   Laura Lopez-Honorez🇧🇪 · Michel H.G. Tytgat🇧🇪 · Pantelis Tziveloglou🇧🇪 · Bryan Zaldivar🇫🇷

   We provide a unified presentation of extensions of the Minimal Dark Matter framework in which new fermionic electroweak multiplets are coupled to each other via the Standard Model Higgs doublet. We study systematically the generic features of all the possibilities, starting with a singlet and two doublets (akin to Bino-Higgsino dark matter) up to a Majorana quintuplet coupled to two Weyl quadruplets. We pay special attention to this last case, since it has not yet been discussed in the literature. We estimate the parameter space for viable dark matter candidates. This includes an estimate for the mass of a quasi-pure quadruplet dark matter candidate taking into account the Sommerfeld effect. We also argue how the coupling to the Higgs can bring the Minimal Dark Matter scenario within the reach of present and future direct detection experiments.

   hep-phJHEP(2018)·37 citations
5. 05*

   Diffusion of conserved charges in relativistic heavy ion collisions

   Moritz Greif🇩🇪 · Jan A. Fotakis🇩🇪 · Gabriel S. Denicol🇧🇷 · Carsten Greiner🇩🇪

   In order to characterize nuclear matter under extreme conditions, we calculate all diffusion transport coefficients related to baryon, electric and strangeness charge for both a hadron resonance gas and a simplified kinetic model of the quark-gluon plasma. We demonstrate that the diffusion currents do not depend only on gradients of their corresponding charge density. Instead, we show that there exists coupling between the different charge currents, in such a way that it is possible for density gradients of a given charge to generate dissipative currents of another charge. Within this scheme, the charge diffusion coefficient is best viewed as a matrix, in which the diagonal terms correspond to the usual charge diffusion coefficients, while the off-diagonal terms describe the coupling between the different currents. In this letter, we calculate for the first time the complete diffusion matrix including the three charges listed above. We find that the baryon diffusion current is strongly affected by baryon charge gradients, but also by its coupling to gradients in strangeness. The electric charge diffusion current is found to be strongly affected by electric and strangeness gradients, whereas strangeness currents depend mostly on strange and baryon gradients.

   hep-phnucl-thPRL(2018)·92 citations
6. 06*

   The $\eta /s$ of the LQCD-EoS complied hadron gas of different sizes approach common minimum near the crossover temperature

   Nachiketa Sarkar🇮🇳 · Premomoy Ghosh🇮🇳

   We study the temperature dependence of the ratio of the shear viscosity to entropy density for the LQCD-contrasted hadron resonance gas of different finite system-sizes, which may represent the final state hadronic matter, formed in systems of ultra-relativistic collisions. The transport coefficient reaches the lowest common value, for the systems of different sizes of thermalized hadron gas, near the critical temperature $T_c$ of the QCD crossover.

   hep-phEPJA(2018)·5 citations
7. 07*

   Spectral modulation of non-Galactic plane Gamma-ray pulsars due to photon-ALPs mixing in Galactic magnetic field

   Jhilik Majumdar🇩🇪 · Francesca Calore🇫🇷 · Dieter Horns🇩🇪

   In many approaches to describe physics beyond the standard model, light Nambu-Goldstone bosons (named axion-like particles or ALPS for their similarity with the axion) are predicted to exist. For ALPs with a mass of neV, photon-ALPs oscillation takes place in extra-galactic magnetic fields during the propagation of very high energy gamma-ray photons leading to excess radiation observed for optically thick sources. In order to verify this effect, gamma-ray spectra from strong Galactic plane or non-galactic plane sources can be used and the photon-ALPs mixing would lead to an energy dependent suppression of the observed gamma-ray spectra. Here, we have used Fermi-LAT observations of a sample of non Galactic plane gamma-ray pulsars located at different line-of-sights to search for spectral signatures and compare the result with the predictions using particular models for the Galactic magnetic field.We find consistent evidence with our prevoius analysis of objects located in the Galactic plane for a modulation of the spectra investigated at the level of 3.66 standard deviations . In the framework of ALPS-photon oscillation, the resulting parameters strongly depend upon the chosen magnetic field model, but seem to be within reach of new experiments(e.g. IAXO).

   hep-phPoS(2020)·8 citations
8. 08*

   Unitarity and predictiveness in new Higgs inflation

   Jacopo Fumagalli🇳🇱 · Sander Mooij🇨🇭 · Marieke Postma🇳🇱

   In new Higgs inflation the Higgs kinetic terms are non-minimally coupled to the Einstein tensor, allowing the Higgs field to play the role of the inflaton. The new interaction is non-renormalizable, and the model only describes physics below some cutoff scale. Even if the unknown UV physics does not affect the tree level inflaton potential significantly, it may still enter at loop level and modify the running of the Standard Model (SM) parameters. This is analogous to what happens in the original model for Higgs inflation. A key difference, though, is that in new Higgs inflation the inflationary predictions are sensitive to this running. Thus the boundary conditions at the EW scale as well as the unknown UV completion may leave a signature on the inflationary parameters. However, this dependence can be evaded if the kinetic terms of the SM fermions and gauge fields are non-minimally coupled to gravity as well. Our approach to determine the model's UV dependence and the connection between low and high scale physics can be used in any particle physics model of inflation.

   hep-phastro-ph.COhep-thJHEP(2018)·41 citations
9. 09*

   Light scalar mesons and two-kaon correlation functions

   N.N. Achasov🇷🇺 · A.V. Kiselev🇷🇺

   It is shown that the recent data on the $K_S^0{K}^{+}$ correlation in Pb-Pb interactions agree with the data on the $\gamma \gamma \to \eta {\pi }^0$ and $\varphi \to \eta {\pi }^0\gamma$ reactions and support the four-quark model of the $a_0(980)$ meson. It is shown that the data does not contradict the validity of the Gaussian assumption. The study of two-kaon correlations could provide more information about light scalar mesons after increasing the accuracy of the experimental and theoretical descriptions.

   hep-phhep-exnucl-thPRD(2018)·19 citations
10. 10*

    A simple expression for the four-point scalar function from Gaussian integrals and Fourier transform

    Kamel Benhaddou

    Recasting the $N$-point one loop scalar integral from Feynman to Schwinger parameters gives an integrand with a Gaussian form. By application of a Fourier transform, it is easy to derive explicit expressions for the two, three and four-point functions. The Fourier transformation disentangles singularities in the complex plane and extract their contribution as two-point functions in two dimensions. We explicitly derive a one dimensional expression for the (4D) four-point function whose integrand involves only square root and arcsine functions. This report is a condensed version of the approach developed in \cite{Benhaddou2016} which does not make use of probabilistic jargon.

    hep-phmath-phmath.MP0 citations
11. 11*

    Quark-lepton complementarity model based predictions for ${\theta }_{23}^{PMNS}$ with neutrino mass hierarchy

    Gazal Sharma🇮🇳 · Shankita Bhardwaj🇮🇳 · B. C. Chauhan🇮🇳 · Surender Verma🇮🇳

    After the successful investigation and confirmation of non zero ${\theta }_{13}^{PMNS}$ by various experiments, we are standing at a square where we still encounter a number of issues, which are to be settled. In this paper, we have extended our recent work towards a precise prediction of the ${\theta }_{23}^{PMNS}$ mixing angle, taking into account the neutrino mass hierarchy. We parameterize the non-trivial correlation between quark (CKM) and lepton (PMNS) mixing matrices in quark-lepton complementarity (QLC) model as $V_c=U_{CKM}.\psi .U_{PMNS}$, where $\psi$ is a diagonal phase matrix. Monte Carlo simulations are used to estimate the texture of $V_c$ and compare the results with the standard Tri-Bi-Maximal (TBM) and Bi-Maximal(BM) structures of neutrino mixing matrix. We have predicted the value of ${\theta }_{23}^{PMNS}$ for normal and inverted neutrino mass hierarchies. The value of ${\theta }_{23}^{PMNS}$ obtained for two cases are about $1.3\sigma$ away from each other, implying the better precision can give us a strong hint for the type of neutrino mass hierarchy.

    hep-phSpringer Proc.Phys.(2018)·5 citations
12. 12*

    Localization of Interacting Fields in Five-Dimensional Braneworld Models

    Dewi Wulandari🇮🇩 · Triyanta🇮🇩 · Jusak S. Kosasih🇮🇩 · Douglas Singleton🇺🇸 · Preston Jones🇺🇸

    We study localization properties of fundamental fields which are coupled to one another through the gauge mechanism both in the original Randall-Sundrum (RS) and in the modified Randall-Sundrum (MRS) braneworld models: scalar-vector, vector-vector, and spinor-vector configuration systems. For this purpose we derive conditions of localization, namely the finiteness of integrals over the extra coordinate in the action of the system considered. We also derive field equations for each of the systems and then obtain their solutions corresponding to the extra dimension by a separation of variable method for every field involved in each system. We then insert the obtained solutions into the conditions of localization to seek whether or not the solutions are in accordance with the conditions of localization. We obtain that not all of the configuration systems considered are localizable on the brane of the original RS model while, on the contrary, they are localizable on the MRS braneworld model with some restrictions. In terms of field localizability on the brane, this result shows that the MRS model is much better than the original RS model.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.A(2017)·8 citations
13. 13*

    Dynamical onset of superconductivity and retention of magnetic fields in cooling neutron stars

    Wynn C.G. Ho🇬🇧 · Nils Andersson🇬🇧 · Vanessa Graber🇨🇦

    A superconductor of paired protons is thought to form in the core of neutron stars soon after their birth. Minimum energy conditions suggest magnetic flux is expelled from the superconducting region due to the Meissner effect, such that the neutron star core is largely devoid of magnetic fields for some nuclear equation of state and proton pairing models. We show via neutron star cooling simulations that the superconducting region expands faster than flux is expected to be expelled because cooling timescales are much shorter than timescales of magnetic field diffusion. Thus magnetic fields remain in the bulk of the neutron star core for at least 10^6-10^7 yr. We estimate the size of flux free regions at 10^7 yr to be <~ 100 m for a magnetic field of 10^11 G and possibly smaller for stronger field strengths. For proton pairing models that are narrow, magnetic flux may be completely expelled from a thin shell of approximately the above size after 10^5 yr. This shell may insulate lower conductivity outer layers, where magnetic fields can diffuse and decay faster, from fields maintained in the highly conducting deep core.

    ↳ astro-ph.HEcond-mat.supr-conhep-phnucl-thPRC(2017)·19 citations
14. 14*

    Hard exclusive pion electroproduction at backward angles with CLAS

    K. Park · M. Guidal · R.W. Gothe · B. Pire · K. Semenov-Tian-Shansky · J.-M. Laget

    We report on the first measurement of cross sections for exclusive deeply virtual pion electroproduction off the proton, $ep\to e^{\prime }n{\pi }^{+}$, above the resonance region at backward pion center-of-mass angles. The ${\phi }_{\pi }^{\ast }$-dependent cross sections were measured, from which we extracted three combinations of structure functions of the proton. Our results are compatible with calculations based on nucleon-to-pion transition distribution amplitudes (TDAs) and shed new light on nucleon structure.

    ↳ nucl-exhep-exhep-phnucl-thPLB(2018)·30 citations
15. 15*

    Hydrodynamic predictions for 5.44 TeV Xe+Xe collisions

    Giuliano Giacalone🇫🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Matthew Luzum🇧🇷 · Jean-Yves Ollitrault🇫🇷

    We argue that relativistic hydrodynamics is able to make robust predictions for soft particle production in Xe+Xe collisions at the CERN Large Hadron Collider (LHC). The change of system size from Pb+Pb to Xe+Xe provides a unique opportunity to test the scaling laws inherent to fluid dynamics. Using event-by-event hydrodynamic simulations, we make quantitative predictions for several observables: mean transverse momentum, anisotropic flow coefficients, and their fluctuations. Results are shown as function of collision centrality.

    ↳ nucl-thhep-phnucl-exPRC(2018)·139 citations
16. 16*

    Non-Gaussianities in a two-field generalization of Natural Inflation

    Simon Riquelme🇺🇸

    We describe a two-field model that generalizes Natural Inflation, in which the inflaton is the pseudo-Goldstone boson of an approximate symmetry that is spontaneously broken, and the radial mode is dynamical. We analyze how the dynamics fundamentally depends on the mass of the radial mode and calculate/estimate the non-Gaussianities arising from such a scenario.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2018)·16 citations
17. 17*

    Relativistic stars in vector-tensor theories

    Ryotaro Kase🇯🇵 · Masato Minamitsuji🇵🇹 · Shinji Tsujikawa🇯🇵

    We study relativistic star solutions in second-order generalized Proca theories characterized by a $U(1)$-breaking vector field with derivative couplings. In the models with cubic and quartic derivative coupling, the mass and radius of stars become larger than those in general relativity for negative derivative coupling constants. This phenomenon is mostly attributed to the increase of star radius induced by a slower decrease of the matter pressure compared to general relativity. There is a tendency that the relativistic star with a smaller mass is not gravitationally bound for a low central density and hence dynamically unstable, but that with a larger mass is gravitationally bound. On the other hand, we show that the intrinsic vector-mode couplings give rise to general relativistic solutions with a trivial field profile, so the mass and radius are not modified from those in general relativity.

    ↳ gr-qcastro-ph.COhep-phhep-thPRD(2018)·40 citations
18. 18*

    Heavy quarks and quarkonia production in high-energy experiments

    Sandro Palestini (CERN)🇨🇭

    Proton-proton collisions at the LHC provide the ground for tests of the strong interactions through the study of the production mechanisms for quarkonia and hadrons containing charm or beauty flavours. This review addresses recent results and includes studies of kinematical correlations, polarisation and associated production. QCD-based models are briefly discussed and compared to measurements.

    ↳ hep-exhep-phPoS(2018)·0 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.