Mon·Mar 6, 2017Monday·March 6, 2017

1. 01*

   Kaon-Nucleon scattering states and potentials in the Skyrme model

   Takashi Ezoe🇯🇵 · Atsushi Hosaka🇯🇵

   We study the (anti)kaon nucleon interaction in the Skyrme model. The kaon field is introduced as a fluctuation around the rotating Skyrmion for the nucleon. As an extension of our previous work, we study scattering states and examine phase shifts in various kaon-nucleon channels. Then we study the interaction, where we find that it consists of central and spin-orbit components for isospin channels, $I=0,1$, with energy dependence and nonlocality. The interaction is then fitted to a Shrödinger equivalent local potential for s- and p-waves.

   hep-phnucl-thPRD(2017)·6 citations
2. 02*

   Meson Spectral Functions at Finite Temperature and Isospin Density with Functional Renormalization Group

   Ziyue Wang🇨🇳 · Pengfei Zhuang🇨🇳

   The pion superfluid and the corresponding Goldstone and soft modes are investigated in two-flavor quark-meson model with functional renormalization group. By solving the flow equations for the effective potential and the meson two-point functions at finite temperature and isospin density, the critical temperature for the superfluid increases sizeably in comparison with solving the flow equation for the potential only. The spectral function for the soft mode shows clearly a transition from meson gas to quark gas with increasing temperature and a crossover from BEC to BCS pairing of quarks with increasing isospin density.

   hep-phnucl-thPRD(2017)·34 citations
3. 03*

   Decay behaviors of Pc hadronic molecules

   Yong-hui Lin🇨🇳 · Chao-wei Shen🇨🇳 · Feng-kun Guo🇨🇳 · Bing-song Zou🇨🇳

   The $P_c(4380)$ and $P_c(4450)$ states observed recently by LHCb experiment were proposed to be either $\bar{D}{\Sigma }_c^{\ast }$ or ${\bar{D}}^{\ast }{\Sigma }_c$ S-wave bound states of spin parity $J^P={\frac{3}{2}}^{-}$. We analyze the decay behaviors of such two types of hadronic molecules within the effective Lagrangian framework. With branching ratios of ten possible decay channels calculated, it is found that the two types of hadronic molecules have distinguishable decay patterns. While the $\bar{D}{\Sigma }_c^{\ast }$ molecule decays dominantly to ${\bar{D}}^{\ast }{\Lambda }_c$ channel with a branching ratio by 2 orders of magnitude larger than to $\bar{D}{\Lambda }_c$, the ${\bar{D}}^{\ast }{\Sigma }_c$ molecule decays to these two channels with a difference of less than a factor of 2. Our results show that the total decay width of $P_c(4380)$ as the spin-parity-${\frac{3}{2}}^{-}$ $\bar{D}{\Sigma }_c^{\ast }$ molecule is about a factor of 2 larger than the corresponding value for the ${\bar{D}}^{\ast }{\Sigma }_c$ molecule. It suggests that the assignment of $\bar{D}{\Sigma }_c^{\ast }$ molecule for $P_c(4380)$ is more favorable than the ${\bar{D}}^{\ast }{\Sigma }_c$ molecule. In addition, $P_c(4450)$ seems to be a ${\bar{D}}^{\ast }{\Sigma }_c$ molecule with $J^P={\frac{5}{2}}^{+}$ in our scheme. Based on these partial decay widths of $P_c(4380)$, we estimate the cross sections for the reactions $\gamma p\to J/\psi p$ and $\pi p\to J/\psi p$ through the s-channel $P_c(4380)$ state. The forthcoming $\gamma p$ experiment at JLAB and $\pi p$ experiment at JPARC should be able to pin down the nature of these $P_c$ states.

   hep-phPRD(2017)·75 citations
4. 04*

   Symmetric point 4-point functions at one loop in QCD

   J.A. Gracey🇬🇧

   We evaluate the quartic ghost and quark Green's functions as well as the gluon-ghost, gluon-quark and ghost-quark 4-point functions of Quantum Chromodynamics at one loop at the fully symmetric point in a linear covariant gauge. Similar expressions for the analogous Green's functions in Quantum Electrodynamics are also provided.

   hep-phPRD(2017)·16 citations
5. 05*

   A "Gauged" $U(1)$ Peccei-Quinn Symmetry

   Hajime Fukuda🇯🇵 · Masahiro Ibe🇯🇵 · Motoo Suzuki🇯🇵 · Tsutomu T. Yanagida🇯🇵

   The Peccei-Quinn (PQ) solution to the strong $CP$ problem requires an anomalous global $U(1)$ symmetry, the PQ symmetry. The origin of such a convenient global symmetry is quite puzzling from the theoretical point of view in many aspects. In this paper, we propose a simple prescription which provides an origin of the PQ symmetry. There, the global $U(1)$ PQ symmetry is virtually embedded in a gauged $U(1)$ PQ symmetry. Due to its simplicity, this mechanism can be implemented in many conventional models with the PQ symmetry.

   hep-phPLB(2017)·93 citations
6. 06*

   Can X(3915) be the tensor partner of the X(3872)?

   V. Baru🇩🇪 · C. Hanhart🇩🇪 · A.V. Nefediev🇷🇺

   It has been proposed recently (Phys. Rev. Lett. 115 (2015), 022001) that the charmoniumlike state named X(3915) and suggested to be a $0^{++}$ scalar, is just the helicity-0 realisation of the $2^{++}$ tensor state ${\chi }_{c2}(3930)$. This scenario would call for a helicity-0 dominance, which were at odds with the properties of a conventional tensor charmonium, but might be compatible with some exotic structure of the ${\chi }_{c2}(3930)$. In this paper, we investigate, if such a scenario is compatible with the assumption that the ${\chi }_{c2}(3930)$ is a $D^{\ast }{\bar{D}}^{\ast }$ molecular state - a spin partner of the $X(3872)$ treated as a shallow bound state. We demonstrate that for a tensor molecule the helicity-0 component vanishes for vanishing binding energy and accordingly for a shallow bound state a helicity-2 dominance would be natural. However, for the ${\chi }_{c2}(3930)$, residing about 100 MeV below the $D^{\ast }{\bar{D}}^{\ast }$ threshold, there is no a priori reason for a helicity-2 dominance and thus the proposal formulated in the above mentioned reference might indeed point at a molecular structure of the tensor state. Nevertheless, we find that the experimental data currently available favour a dominant contribution of the helicity-2 amplitude also in this scenario, if spin symmetry arguments are employed to relate properties of the molecular state to those of the X(3872). We also discuss what research is necessary to further constrain the analysis.

   hep-phhep-exnucl-thJHEP(2017)·20 citations
7. 07*

   Role of a triangle singularity in the $\pi N(1535)$ contribution to $\gamma p\to p{\pi }^0\eta$

   V. R. Debastiani🇪🇸 · S. Sakai🇪🇸 · E. Oset🇪🇸

   We have studied the $\gamma p\to p{\pi }^0\eta$ reaction paying attention to the two main mechanisms at low energies, the $\gamma p\to \Delta (1700)\to \eta \Delta (1232)$ and the $\gamma p\to \Delta (1700)\to \pi N(1535)$. Both of them are driven by the photoexcitation of the $\Delta (1700)$ and the second one involves a mechanism that leads to a triangle singularity. We are able to evaluate quantitatively the cross section for this process and show that it agrees with the experimental determination. Yet, there are some differences with the standard partial wave analysis which does not include explicitly the triangle singularity. The exercise also shows the convenience to explore possible triangle singularities in other reactions and how a standard partial analysis can be extended to accommodate them.

   hep-phPRC(2017)·33 citations
8. 08*

   Perspectives of direct Detection of supersymmetric Dark Matter in the NMSSM

   C. Beskidt (1)🇩🇪 · W. de Boer (1)🇩🇪 · D. I. Kazakov (1,2)🇷🇺 · S. Wayand (1) ((1) Karlsruhe Institute of Technology, Germany, (2) Bogoliubov Laboratory of Theoretical Physics, JINR, Dubna, Russia)🇩🇪

   In the Next-to-Minimal-Supersymmetric-Standard-Model (NMSSM) the lightest supersymmetric particle (LSP) is a candidate for the dark matter (DM) in the universe. It is a mixture from the various gauginos and Higgsinos and can be bino-, Higgsino- or singlino-dominated. Singlino-dominated LSPs can have very low cross sections below the neutrino background from coherent neutrino scattering which is limiting the sensitivity of future direct DM search experiments. However, previous studies suggested that the combination of both, the spin-dependent (SD) and spin-independent (SI) searches are sensitive in complementary regions of parameter space, so considering both searches will allow to explore practically the whole parameter space of the NMSSM. In this letter, the different scenarios are investigated with a new scanning technique, which reveals that significant regions of the NMSSM parameter space cannot be explored, even if one considers both, SI and SD, searches.

   hep-phastro-ph.COPLB(2017)·18 citations
9. 09*

   Nucleon structure functions from lattice operator product expansion

   A.J. Chambers🇦🇺 · R. Horsley🇬🇧 · Y. Nakamura🇯🇵 · H. Perlt🇩🇪 · P.E.L. Rakow🇬🇧 · G. Schierholz🇩🇪 · A. Schiller🇩🇪 · K. Somfleth🇦🇺 · R.D. Young🇦🇺 · J.M. Zanotti🇦🇺

   Deep-inelastic scattering, in the laboratory and on the lattice, is most instructive for understanding how the nucleon is built from quarks and gluons. The long-term goal is to compute the associated structure functions from first principles. So far this has been limited to model calculations. In this Letter we propose a new method to compute the structure functions directly from the virtual, all-encompassing Compton amplitude, utilizing the operator product expansion. This overcomes issues of renormalization and operator mixing, which so far have hindered lattice calculations of power corrections and higher moments.

   ↳ hep-lathep-exhep-phnucl-thPRL(2017)·245 citations
10. 10*

    The frozen nucleon approximation in two-particle two-hole response functions

    I. Ruiz Simo🇪🇸 · J.E. Amaro🇪🇸 · M.B. Barbaro🇮🇹 · J.A. Caballero🇪🇸 · G.D. Megias🇪🇸 · T.W. Donnelly🇺🇸

    We present a fast and efficient method to compute the inclusive two-particle two-hole (2p-2h) electroweak responses in the neutrino and electron quasielastic inclusive cross sections. The method is based on two approximations. The first neglects the motion of the two initial nucleons below the Fermi momentum, which are considered to be at rest. This approximation, which is reasonable for high values of the momentum transfer, turns out also to be quite good for moderate values of the momentum transfer $q\gtrsim k_F$. The second approximation involves using in the "frozen" meson-exchange currents (MEC) an effective $\Delta$-propagator averaged over the Fermi sea. Within the resulting "frozen nucleon approximation", the inclusive 2p-2h responses are accurately calculated with only a one-dimensional integral over the emission angle of one of the final nucleons, thus drastically simplifying the calculation and reducing the computational time. The latter makes this method especially well-suited for implementation in Monte Carlo neutrino event generators.

    ↳ nucl-thhep-phPLB(2017)·18 citations
11. 11*

    Tree-level correlations in the strong field regime

    Francois Gelis🇫🇷

    We consider the correlation function of an arbitrary number of local observables in quantum field theory. We show that, at tree level in the strong field regime, these correlations arise solely from fluctuations in the initial state. We obtain the general expression of these correlation functions in terms of the classical solution of the field equation of motion and its derivatives with respect to its initial conditions, that can be arranged graphically as the sum of labeled trees where the nodes are the individual observables, and the links are pairs of derivatives acting on them. For 3-point (and higher) correlation functions, there are additional tree-level terms beyond from the strong field approximation, generated throughout the evolution of the system.

    ↳ hep-thhep-phnucl-thJHEP(2017)·0 citations
12. 12*

    Dipole polarizabilities of charged pions

    L.V. Fil'kov🇷🇺 · V.L. Kashevarov🇩🇪

    We discuss main experimental works, where dipole polarizabilities of charged pions have been determined. Possible reasons for the differences between the experimental data are discussed. In particular, it is shown that the account of the $\sigma$-meson gives a significant correction to the value of the polarizability obtained in the latest experiment of the COMPASS collaboration.

    ↳ hep-exhep-phnucl-exnucl-thPhys.Part.Nucl.(2017)·8 citations
13. 13*

    On the Flow of $\square R$ Weyl-Anomaly

    Vladimir Prochazka🇬🇧 · Roman Zwicky🇬🇧

    An important aspect of Weyl anomalies is that they encode information on the irreversibility of the renormalisation group flow. We consider, $\Delta \bar{b}={\bar{b}}^{\text{UV}}-{\bar{b}}^{\text{IR}}$, the difference of the ultraviolet and infrared value of the $\square R$-term of the Weyl anomaly. The quantity is related to the fourth moment of the trace of the energy momentum tensor correlator for theories which are conformal at both ends. Subtleties arise for non-conformal fixed points as might be the case for infrared fixed points with broken chiral symmetry. Provided that the moment converges, $\Delta \bar{b}$ is then automatically positive by unitarity. Written as an integral over the renormalisation scale, flow-independence follows since its integrand is a total derivative. Furthermore, using a momentum subtraction scheme (MOM) the 4D Zamolodchikov- metric is shown to be strictly positive beyond perturbation theory and equivalent to the metric of a conformal manifold at both ends of the flow. In this scheme $\bar{b}(\mu )$ can be extended outside the fixed point to a monotonically decreasing function. The ultraviolet finiteness of the fourth moment enables us to define a scheme for the $\delta \mathcal{L}\sim b_0{R}^2$-term, for which the $R^2$-anomaly vanishes along the flow. In the MOM- and the $R^2$-scheme, $\bar{b}(\mu )$ is shown to satisfy a gradient flow type equation. We verify our findings in free field theories, higher derivative theories and extend $\Delta \bar{b}$ and the Euler flow $\Delta {\beta }_a$ for a Caswell-Banks-Zaks fixed point for QCD-like theories to next-to-next-to leading order using a recent $⟨G^2{G}^2⟩$-correlator computation.

    ↳ hep-thhep-phPRD(2017)·13 citations
14. 14*

    Top-Down Holographic $G$-Structure Glueball Spectroscopy at (N)LO in $N$ and Finite Gauge Coupling

    Karunava Sil🇮🇳 · Vikas Yadav🇮🇳 · Aalok Misra🇮🇳

    The top-down type IIB holographic dual of large-$N$ thermal QCD as constructed in arXiv:0902.1540 involving a fluxed resolved warped deformed conifold, its delocalized type IIA SYZ mirror as well as its M-theory uplift constructed in arXiv:1306.4339 - both in the finite gauge coupling ($g_s\stackrel{<}{\sim }1$)/`MQGP' limit of arXiv:1306.4339 - were shown explicitly to possess a local $SU(3)/G_2$-structure in arXiv:1507.02692 Glueball spectroscopy at finite gauge coupling has thus far been missing in the literature. In this paper, we fill this gap by calculating the masses of the $0^{++},0^{-+},0^{--},1^{++},2^{++}$ (`glueball') states (which correspond to fluctuations in the dilaton or complexified two-forms or appropriate metric components) in the aforementioned backgrounds of $G$-structure in the `MQGP' limit of arXiv:1306.4339, using WKB quantization conditions on one hand and imposing Neumann/Dirichlet boundary conditions at an IR cut-off/horizon radius $r_h$ on the solutions to the equations of motion on the other. We also discuss $r_h=0$-limits of all calculations; in this context we also calculate the $0^{++},0^{--},1^{++},2^{++}$ glueball masses up to NLO in $N$ and find a $\frac{g_s{M}^2}{N}(g_s{N}_f)$-suppression similar to and further validating a similar semi-universality of NLO corrections to transport coefficients, observed in arXiv:1606.04949.

    ↳ hep-thhep-lathep-phEPJC(2017)·18 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.