Mon·Jul 10, 2017Monday·July 10, 2017

1. 01*

   Counting states and the Hadron Resonance Gas: Does X(3872) count?

   Pablo G. Ortega🇪🇸 · David R. Entem🇪🇸 · Francisco Fernandez🇪🇸 · Enrique Ruiz Arriola🇪🇸

   We analyze how the renowned X(3872), a weakly bound state right below the $D{\bar{D}}^{\ast }$ threshold, should effectively be included in a hadronic representation of the QCD partition function. This can be decided by analyzing the $D{\bar{D}}^{\ast }$ scattering phase-shifts in the $J^{PC}=1^{++}$ channel and their contribution to the level density in the continuum from which the abundance in a hot medium can be determined. We show that in a purely molecular picture the bound state contribution cancels the continuum providing a vanishing occupation number density at finite temperature and the $X(3872)$ does not count below the Quark-Gluon Plasma crossover happening at $T\sim 150$MeV. In contrast, within a coupled-channels approach, for a non vanishing $c\bar{c}$ content the cancellation does not occur due to the onset of the $X(3940)$ which effectively counts as an elementary particle for temperatures above $T\gtrsim 250$MeV. Thus, a direct inclusion of the $X(3872)$ in the Hadron Resonance Gas is not justified. We also estimate the role of this cancellation in X(3872) production in heavy-ion collision experiments in terms of the corresponding $p_T$ distribution due to a finite energy resolution.

   hep-phnucl-thPLB(2018)·14 citations
2. 02*

   Inhomogeneous Chiral Phase in Quark Matter

   Toshitaka Tatsumi🇯🇵

   Recent development of inhomogeneous chiral phase in Kyoto group is briefly reviewed. First, the nesting effect of the Fermi surface is emphasized as a key mechanism leading to inhomogeneous chiral phase. After introduction of inhomogeneous chiral phase, some topological aspect is discussed in 1+1 dimensions and in the presence of the magnetic field in 1+3 dimensions. Spectral asymmetry gives rise to anomalous quark number and is closely related to chiral anomaly. It may induce spontaneous magnetization and a novel Lifshitz point may appear on the line $\mu =0$. Some astronomical implications are briefly discussed. Finally, the effects of the fluctuations around the order parameter are discussed; the propagator of the fluctuations exhibits a singularity at finite momentum and changes the properties of the phase transition through loop diagrams.

   hep-phastro-ph.HEnucl-thJPS Conf.Proc.(2018)·2 citations
3. 03*

   Color reconnection effects on resonance production

   R. Acconcia🇧🇷 · D.D. Chinellato🇧🇷 · R. Derradi de Souza🇧🇷 · C. Markert🇺🇸 · J. Takahashi🇧🇷 · G. Torrieri🇧🇷

   We present studies that show how multi-parton interaction and color reconnection affect the hadro-chemistry in proton-proton (pp) collisions with special focus on the production of resonances using the PYTHIA8 event generator. We find that color reconnection suppresses the relative production of meson resonances such as ${\rho }_0$ and K*, providing an alternative explanation for the K*/K decrease observed in proton-proton collisions as a function of multiplicity by the ALICE collaboration. Detailed studies of the underlying mechanism causing meson resonance suppression indicate that color reconnection leads to shorter, less energetic strings whose fragmentation is less likely to produce more massive hadrons for a given quark content, therefore reducing ratios such as K*/K and ${\rho }_0/\pi$ in high-multiplicity pp collisions. In addition, we have also studied the effects of allowing string junctions to form and found that these may also contribute to resonance suppression.

   hep-phPRD(2018)·10 citations
4. 04*

   Colder Freeze-in Axinos Decaying into Photons

   Kyu Jung Bae🇰🇷 · Ayuki Kamada🇰🇷 · Seng Pei Liew🇩🇪 · Keisuke Yanagi🇯🇵

   We point out that 7 keV axino dark matter (DM) in the R-parity violating (RPV) supersymmetric (SUSY) Dine-Fischler-Srednicki-Zhitnitsky model can simultaneously reproduce the 3.5keV X-ray excess, and evade stringent constraints from the Ly-alpha forest data. Peccei-Quinn symmetry breaking naturally generates both axino interactions with minimal SUSY standard model particles and RPV interactions. The RPV interaction introduces an axino-neutrino mixing and provides axino DM as a variant of sterile neutrino DM, whose decay into a monochromatic photon can be detected by X-ray observations. Axinos, on the other hand, are produced by freeze-in processes of thermal particles in addition to the Dodelson-Widrow mechanism of sterile neutrinos. The resultant phase space distribution tends to be colder than the Fermi-Dirac distribution. The inherent entropy production from late-time saxion decay makes axinos even colder. The linear matter power spectrum satisfies even the latest and strongest constraints from the Ly-alpha forest data.

   hep-phastro-ph.COPRD(2018)·13 citations
5. 05*

   Double non-perturbative gluon exchange: an update on the soft Pomeron contribution to pp scattering

   F.E. Canfora🇨🇱 · D. Dudal🇧🇪 · I.F. Justo🇧🇷 · P. Pais🇨🇱 · P. Salgado-Rebolledo🇨🇱 · L. Rosa🇮🇹 · D. Vercauteren🇻🇳

   We employ a set of recent, theoretically motivated, fits to non-perturbative unquenched gluon propagators to check in how far double gluon exchange can be used to describe the soft sector of pp scattering data (total and differential cross section). In particular, we use the refined Gribov--Zwanziger gluon propagator (as arising from dealing with the Gribov gauge fixing ambiguity) and the massive Cornwall-type gluon propagator (as motivated from Dyson-Schwinger equations) in conjunction with a perturbative quark-gluon vertex, next to a model based on the non-perturbative quark-gluon Maris-Tandy vertex, popular from Bethe-Salpeter descriptions of hadronic bound states. We compare the cross sections arising from these models with "older" ISR and more recent TOTEM and ATLAS data. The lower the value of total energy \sqrt{s}, the better the results appear to be.

   hep-phPRC(2017)·6 citations
6. 06*

   Studies of the hydrodynamic evolution of the dense baryonic matter produced in relativistic heavy ion collisions

   Gong-Ming Yu🇨🇳 · Jian-Song Wang🇨🇳

   We use the relativistic perfect-fluid hydrodynamics to describe the space-time evolution of dense baryonic matter produced in the central nucleus-nucleus collisions at HIRFL-CSR, HIAF, FAIR-CBM, NICA-MPD, and RHIC-BES. The transverse flow of the fireball with cylindrical symmetry and boost invariant along the longitudinal direction is also analyzed. Based on the relativistic kinetic theory, we also present the first preliminary calculation on the production of low-mass dileptons and low-pT photons can be considered as the signals of the dense baryonic matter produced in the central Au-Au and U-U collisions. We find that the rapid cooling of the expanding dense baryonic matter with transverse flow effect can lead to the suppression of the low-mass dileptons and low-pT photons production at HIRFL-CSR, HIAF, FAIR-CBM, NICA-MPD, and RHIC-BES energies.

   hep-phnucl-th1 citation
7. 07*

   Abnormal isospin violation and $a_0-f_0$ mixing in the $D_s^{+}\to {\pi }^{+}{\pi }^0{a}_0(980)(f_0(980))$ reactions

   S. Sakai🇪🇸 · E. Oset🇪🇸 · W.H. Liang🇨🇳

   We have chosen the reactions $D_s^{+}\to {\pi }^{+}{\pi }^0{a}_0(980)(f_0(980))$ investigating the isospin violating channel $D_s^{+}\to {\pi }^{+}{\pi }^0{f}_0(980)$. The reaction was chosen because by varying the ${\pi }^0{a}_0(980)(f_0(980))$ invariant mass one goes through the peak of a triangle singularity emerging from $D_s^{+}\to {\pi }^{+}{\bar{K}}^{\ast }K$, followed by ${\bar{K}}^{\ast }\to \bar{K}{\pi }^0$ and the further merging of $K\bar{K}$ to produce the $a_0(980)$ or $f_0(980)$. We found that the amount of isospin violation had its peak precisely at the value of the ${\pi }^0{a}_0(980)(f_0(980))$ invariant mass where the singularity has its maximum, stressing the role of the triangle singularities as a factor to enhance the mixing of the $f_0(980)$ and $a_0(980)$ resonances. We calculate absolute rates for the reactions and show that they are within present measurable range. The measurement of these reactions would bring further information into the role of triangle singularities in isospin violation and the $a_0-f_0$ mixing in particular and shed further light into the nature of the low energy scalar mesons.

   hep-phPRD(2017)·36 citations
8. 08*

   Systematic study of octet-baryon electromagnetic form factors in covariant chiral perturbation theory

   Astrid N. Hiller Blin🇪🇸

   We perform a complete and systematic calculation of the octet-baryon form factors within the fully covariant approach of SU(3) chiral perturbation theory at O(p^3). We use the extended on-mass shell renormalization scheme, and include explicitly the vector mesons and the spin-3/2 decuplet intermediate states. Comparing these predictions with data including magnetic moments, charges, and magnetic radii, we determine the unknown low-energy constants, and give predictions for yet unmeasured observables, such as the magnetic moment of the Sigma^0, and the charge and magnetic radii of the hyperons.

   hep-phPRD(2017)·18 citations
9. 09*

   New theories of relativistic hydrodynamics in the LHC era

   Wojciech Florkowski🇵🇱 · Michal P. Heller🇩🇪 · Michal Spalinski🇵🇱

   The success of relativistic hydrodynamics as an essential part of the phenomenological description of heavy-ion collisions at RHIC and the LHC has motivated a significant body of theoretical work concerning its fundamental aspects. Our review presents these developments from the perspective of the underlying microscopic physics, using the language of quantum field theory, relativistic kinetic theory, and holography. We discuss the gradient expansion, the phenomenon of hydrodynamization, as well as several models of hydrodynamic evolution equations, highlighting the interplay between collective long-lived and transient modes in relativistic matter. Our aim to provide a unified presentation of this vast subject -- which is naturally expressed in diverse mathematical languages -- has also led us to include several new results on the large-order behaviour of the hydrodynamic gradient~expansion.

   hep-phgr-qchep-thnucl-ex+1Rept.Prog.Phys.(2018)·416 citations
10. 10*

    The minimal fermionic model of electroweak baryogenesis

    Daniel Egana-Ugrinovic🇺🇸

    We present the minimal model of electroweak baryogenesis induced by fermions. The model consists of an extension of the Standard Model with one electroweak singlet fermion and one pair of vector like doublet fermions with renormalizable couplings to the Higgs. A strong first order phase transition is radiatively induced by the singlet-doublet fermions, while the origin of the baryon asymmetry is due to asymmetric reflection of the same set of fermions on the expanding electroweak bubble wall. The singlet-doublet fermions are stabilized at the electroweak scale by chiral symmetries and the Higgs potential is stabilized by threshold corrections coming from a multi-TeV ultraviolet completion which does not play any significant role in the phase transition. We work in terms of background symmetry invariants and perform an analytic semiclassical calculation of the baryon asymmetry, showing that the model may effectively generate the observed baryon asymmetry for percent level values of the unique invariant CP violating phase of the singlet-doublet sector. We include a detailed study of electron electric dipole moment and electroweak precision limits, and for one typical benchmark scenario we also recast existing collider constraints, showing that the model is consistent with all current experimental data. We point out that fermion induced electroweak baryogenesis has irreducible phenomenology at the $13\text{TeV}$ LHC since the new fermions must be at the electroweak scale, have electroweak quantum numbers and couple strongly with the Higgs. The most promising searches involve topologies with multiple leptons and missing energy in the final state.

    hep-phJHEP(2017)·33 citations
11. 11*

    Three particle quantization condition in a finite volume: 2. general formalism and the analysis of data

    H.-W. Hammer🇩🇪 · J.-Y. Pang🇩🇪 · A. Rusetsky🇩🇪

    We derive the three-body quantization condition in a finite volume using an effective field theory in the particle-dimer picture. Moreover, we consider the extraction of physical observables from the lattice spectrum using the quantization condition. To illustrate the general framework, we calculate the volume-dependent three-particle spectrum in a simple model both below and above the three-particle threshold. The relation to existing approaches is discussed in detail.

    ↳ hep-lathep-phnucl-thJHEP(2017)·213 citations
12. 12*

    Galileon Gravity in Light of ISW, CMB, BAO and $H_0$ data

    Janina Renk🇸🇪 · Miguel Zumalacárregui🇺🇸 · Francesco Montanari🇫🇮 · Alexandre Barreira🇩🇪

    Cosmological models with Galileon gravity are an alternative to the standard $\Lambda \mathrm{CDM}$ paradigm with testable predictions at the level of its self-accelerating solutions for the expansion history, as well as large-scale structure formation. Here, we place constraints on the full parameter space of these models using data from the cosmic microwave background (CMB) (including lensing), baryonic acoustic oscillations (BAO) and the Integrated Sachs-Wolfe (ISW) effect. We pay special attention to the ISW effect for which we use the cross-spectra, $C_{\ell }^{\mathrm{Tg}}$, of CMB temperature maps and foreground galaxies from the WISE survey. The sign of $C_{\ell }^{\mathrm{Tg}}$ is set by the time evolution of the lensing potential in the redshift range of the galaxy sample: it is positive if the potential decays (like in $\Lambda \mathrm{CDM}$), negative if it deepens. We constrain three subsets of Galileon gravity separately known as the Cubic, Quartic and Quintic Galileons. The cubic Galileon model predicts a negative $C_{\ell }^{\mathrm{Tg}}$ and exhibits a $7.8\sigma$ tension with the data, which effectively rules it out. For the quartic and quintic models the ISW data also rule out a significant region of the parameter space but permit regions where the goodness-of-fit is comparable to $\Lambda \mathrm{CDM}$. The data prefers a non zero sum of the neutrino masses ($\sum m_{\nu }\approx 0.5$eV) with $\sim 5\sigma$ significance in these models. The best-fitting models have values of $H_0$ consistent with local determinations, thereby avoiding the tension that exists in $\Lambda \mathrm{CDM}$. We also identify and discuss a $\sim 2\sigma$ tension that Galileon gravity exhibits with recent BAO measurements. Our analysis shows overall that Galileon cosmologies cannot be ruled out by current data but future lensing, BAO and ISW data hold strong potential to do so.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2017)·215 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.