Inspired by the present experimental results of charged charmonium-like states $Z_c^{+}$, we present a systematic study of the tetraquark states $[cu][\overline{c}\overline{d}]$ in a color flux-tube model with a multibody confinement potential. Our investigation indicates that charged charmonium-like states $Z_c^{+}(3900)$ or $Z_c^{+}(3885)$, $Z_c^{+}(3930)$, $Z_c^{+}(4020)$ or $Z_c^{+}(4025)$, $Z_1^{+}(4050)$, $Z_2^{+}(4250)$, and $Z_c^{+}(4200)$ can be described as a family of tetraquark $[cu][\overline{c}\overline{d}]$ states with the quantum numbers $n{{}^{2S+1}L}_J$ and $J^P$ of $1{{}^{3}S}_1$ and $1^{+}$, $2{{}^{3}S}_1$ and $1^{+}$, $1{{}^{5}S}_2$ and $2^{+}$, $1{{}^{3}P}_1$ and $1^{-}$, $1{{}^{5}D}_1$ and $1^{+}$, and $1{{}^{3}D}_1$ and $1^{+}$, respectively. The predicted lowest mass charged tetraquark state $[cu][\overline{c}\overline{d}]$ with $0^{+}$ and $1{{}^{1}S}_0$ lies at $3780\pm 10\mathrm{MeV}/{\mathrm{c}}^2$ in the model. These tetraquark states have compact three-dimensional spatial configurations similar to a rugby ball with higher orbital angular momentum $L$ between the diquark $[cu]$ and antidiquark $[\overline{c}\overline{d}]$ corresponding to a more prolate spatial distribution. The multibody color flux tube, a collective degree of freedom, plays an important role in the formation of those charged tetraquark states. However, the two heavier charged states $Z_c^{+}(4430)$ and $Z_c^{+}(4475)$ cannot be explained as tetraquark states $[cu][\overline{c}\overline{d}]$ in this model approach.

We revisit the issue of the large negative next-to-leading-order (NLO) cross section for single inclusive hadron production in $\mathrm{p}A$ collisions in the saturation formalism. By implementing the exact kinematical constraint in the modified dipole splitting functions, two additional positive NLO correction terms are obtained. In the asymptotic large-$k_{\perp }$ limit, we analytically show that these two terms become as large as the negative NLO contributions found in our previous calculation. Furthermore, the numerical results demonstrate that the applicable regime of the saturation formalism can be extended to a larger $k_{\perp }$ window, where the exact matching between the saturation formalism (in the asymptotic $k_{\perp }$ regime) and the collinear factorization calculations will have to be performed separately. In addition, after significantly improving the numerical accuracy of the NLO correction, we obtain excellent agreement with the LHC and RHIC data for forward hadron productions.

The decay $Z_c(3900{)}^{\pm }\to \omega {\pi }^{\pm }$ is searched for using data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies $\sqrt{s}=4.23$ and 4.26 GeV. No significant signal for the $Z_c(3900{)}^{\pm }$ is found, and upper limits at the 90% confidence level on the Born cross section for the process $e^{+}{e}^{-}\to Z_c(3900{)}^{\pm }{\pi }^{\mp }\to \omega {\pi }^{+}{\pi }^{-}$ are determined to be 0.26 and 0.18 pb at $\sqrt{s}=4.23$ and 4.26 GeV, respectively.

The cross section for formation in $\gamma +p$ collisions of the recently found hidden-charm pentaquark states $P_c(4380)$ and $P_c(4450)$ is discussed and estimated. The studies of these resonances in photon beam experiments can be complementary to those in the LHCb experiment setting, and may be more advantageous for measurement of their additional decay channels. It is pointed out that both the relative importance of such decays and the yield of the resonances in the $\gamma +p$ collisions are sensitive to the internal dynamics of the pentaquarks and can resolve between theoretical models. Specific numerical estimates are discussed within a simple “baryocharmonium” model, where the observed $P_c$ resonances are composites of $J/\psi$ and excited nucleon states with the quantum numbers of $N(1440)$ and $N(1520)$.

We study the spectrum and short-distance two-body force of holographic baryons by the matrix model, which is derived from the Sakai-Sugimoto model in the D0-D4 background (D0-D4/D8 system). The matrix model is derived by using the standard technique in string theory, and it can describe multibaryon systems. We rederive the action of the matrix model from open string theory on the baryon vertex, which is embedded in the D0-D4/D8 system. The matrix model offers a more systematic approach to the dynamics of the baryons at short distances. In our system, we find that the matrix model describes stable baryonic states only if $\zeta =U_{Q_0}^3/U_{KK}^3<2$, where $U_{Q_0}^3$ is related to the number density of smeared D0-branes. This result in our paper is exactly the same as some previous results studied in this system, presented in [W. Cai, C. Wu, and Z. Xiao, Phys. Rev. D 90, 106001 (2014)]. We also compute the baryon spectrum ($k=1$ case) and short-distance two-body force of baryons ($k=2$ case). The baryon spectrum is modified and could be able to fit the experimental data if we choose a suitable value for $\zeta$. And the short-distance two-body force of baryons is also modified by the appearance of smeared D0-branes from the original Sakai-Sugimoto model. If $\zeta >2$, we find that the baryon spectrum will be totally complex and an attractive force will appear in the short-distance interaction of baryons, which may consistently correspond to the existence of unstable baryonic states.

This paper studies a special class of states for the dual conformal field theories associated with supersymmetric ${\mathrm{AdS}}_5\times X$ compactifications, where $X$ is a Sasaki-Einstein manifold with additional $U(1)$ symmetries. Under appropriate circumstances, it is found that elements of the chiral ring that maximize the additional $U(1)$ charge at fixed R-charge are in one to one correspondence with multitraces of a single composite field. This is also equivalent to Schur functions of the composite field. It is argued that in the formal zero coupling limit that these dual field theories have, the different Schur functions are orthogonal. Together with large $N$ counting arguments, one predicts that various extremal three point functions are identical to those of $\mathcal{N}=4$ SYM, except for a single normalization factor, which can be argued to be related to the R-charge of the composite word. The leading and subleading terms in $1/N$ are consistent with a system of free fermions for a generalized oscillator algebra. One can further test this conjecture by constructing coherent states for the generalized oscillator algebra that can be interpreted as branes exploring a subset of the moduli space of the field theory and use these to compute the effective Kähler potential on this subset of the moduli space.

A holographic description on the antiferromagnetic quantum phase transition (QPT) induced by the magnetic field and the criticality in the vicinity of the quantum critical point have been investigated numerically recently. In this paper, we show that the properties of QPT in this holographic model are governed by a CFT dual to the emergent ${\mathrm{AdS}}_2$ in the IR region, which confirms that the dual boundary theory is a strong coupling theory with dynamic exponent $z=2$ and logarithmic corrections appearing. We also compare them with the results from the Hertz model by solving the RG equation at its upper critical dimension and with some experimental data from pyrochlores ${\mathrm{Er}}_{2-2x}{\mathrm{Y}}_{2x}{\mathrm{Ti}}_2{\mathrm{O}}_7$ and ${\mathrm{BiCoPO}}_5$.

We point out the existence of a nonperturbative exact nilpotent BRST symmetry for the Gribov-Zwanziger action in the Landau gauge. We then put forward a manifestly BRST invariant resolution of the Gribov gauge fixing ambiguity in the linear covariant gauge.

We propose that, in $SU(3)$ gauge theories with fundamental quarks, confinement can be inferred from spectral density of the Dirac operator. This stems from the proposition that its possible behaviors are exhausted by three distinct types (Fig. 1). The monotonic cases are standard and entail confinement with valence chiral symmetry breaking (A) or the lack of both (C,C’). The bimodal (anomalous) option (B) was frequently regarded as an artifact (lattice or other) in previous studies, but we show for the first time that it persists in the continuum limit, and conclude that it informs of a nonconfining phase with broken valence chiral symmetry. This generalization rests on the following. $(\alpha )$ We show that bimodality in ${\mathrm{N}}_f=0$ theory past deconfinement temperature $T_c$ is stable with respect to removal of both infrared and ultraviolet cutoffs, indicating that anomalous phase is not an artifact. $(\beta )$ We demonstrate that transition to bimodality in ${\mathrm{N}}_f=0$ is simultaneous with the loss of confinement: anomalous phase occurs for $T_c<T<T_{ch}$, where $T_{ch}$ is the valence chiral restoration temperature. $(\gamma )$ Evidence is presented for thermal anomalous phase in ${\mathrm{N}}_f=2+1$ QCD at physical quark masses, whose onset too coincides with the conventional “crossover $T_c$.” We conclude that the anomalous regime $T_c<T<T_{ch}$ is very likely a feature of nature’s strong interactions. $(\delta )$ Our past studies of zero-temperature ${\mathrm{N}}_f=12$ theories revealed that bimodality also arises via purely light-quark effects. As a result, we expect to encounter the anomalous phase on generic paths to valence chiral restoration. We predict its existence also for $N_f$ massless flavors ($T=0$) in the range ${\mathrm{N}}_f^c<{\mathrm{N}}_f<{\mathrm{N}}_f^{ch}$, where ${\mathrm{N}}_f^c$ could be quite low. Conventional arguments would associate ${\mathrm{N}}_f^{ch}$ with the onset of conformal window.

We show that the stress-energy tensor has additional terms with respect to the ideal form in states of global thermodynamic equilibrium in flat spacetime with nonvanishing acceleration and vorticity. These corrections are of quantum origin and their leading terms are second order in the gradients of the thermodynamic fields. Their relevant coefficients can be expressed in terms of correlators of the stress-energy tensor operator and the generators of the Lorentz group. With respect to previous assessments, we find that there are more second-order coefficients and that all thermodynamic functions including energy density receive acceleration and vorticity dependent corrections. Notably, also the relation between $\rho$ and $p$, that is, the equation of state, is affected by acceleration and vorticity. We have calculated the corrections for a free real scalar field—both massive and massless—and we have found that they increase, particularly for a massive field, at very high acceleration and vorticity and very low temperature. Finally, these nonideal terms depend on the explicit form of the stress-energy operator, implying that different stress-energy tensors of the scalar field—canonical or improved—are thermodynamically inequivalent.

Spontaneous symmetry breaking with necessity leads to the presence of Goldstone field(s). In the case of scale or conformal symmetries the corresponding Goldstone mode is called the dilaton. Consistently coupling a system to the dilaton poses certain difficulties, for the trace of the energy momentum tensor may not necessary be zero, which in turn leads to the dilaton acquiring a mass. In this paper we present the approach allowing perturbatively to keep the dilaton massless, i.e. to preserve conformal symmetry, at any fixed order in perturbation theory.

We systematically examine the properties of null geodesics around an electrically charged, asymptotically flat black hole in Eddington-inspired Born-Infeld gravity, varying the electric charge of the black hole and the coupling constant in the theory. We find that the radius of the unstable circular orbit for a massless particle decreases with the coupling constant, if the value of the electrical charge is fixed. Additionally, we consider the strong gravitational lensing around such a black hole. We show that the deflection angle, the position angle of the relativistic images, and the magnification due to the light bending in strong gravitational field are quite sensitive to the parameters determining the black hole solution. Thus, through the accurate observations associated with the strong gravitational lensing, it might be possible to reveal the gravitational theory in a strong field regime.

The general stationary cylindrically symmetric solution of Einstein-massless scalar field system with a nonpositive cosmological constant is presented. It is shown that the general solution is characterized by four integration constants. Two of these essential parameters have a local meaning and characterize the gravitational field strength. The other two have a topological origin, as they define an improper coordinate transformation that provides the stationary solution from the static one. The Petrov scheme is considered to explore the effects of the scalar field on the algebraic classification of the solutions. In general, these spacetimes are of type I. However, the presence of the scalar field allows us to find a nonvacuum type O solution and a wider family of type D spacetimes, in comparison with the vacuum case. The mass and angular momentum of the solution are computed using the Regge-Teitelboim method in the case of a negative cosmological constant. In absence of a cosmological constant, the curvature singularities in the vacuum solutions can be removed by including a phantom scalar field, yielding nontrivial locally homogeneous spacetimes. These spacetimes are of particular interest, as they have all their curvature invariants constant.

We consider the sector of Horndeski’s gravity characterized by the coupling between the kinetic scalar field term and the Einstein tensor. We numerically construct neutron star configurations where the external geometry is identical to the Schwarzschild metric but the interior structure is considerably different from standard general relativity. We constrain the only parameter of this model from the requirement that compact configurations exist, and we argue that solutions less compact than neutron stars, such as white dwarfs, are also supported. Therefore, our model provides an explicit modification of general relativity that is astrophysically viable and does not conflict with Solar System tests.

An interaction between dark matter and dark energy is usually introduced by a phenomenological modification of the matter conservation equations, while the Einstein equations are left unchanged. Starting from some general and fundamental considerations, in this work it is shown that a coupling in the dark sector is likely to introduce new terms also in the gravitational dynamics. Specifically in the cosmological background equations a bulk dissipative pressure, characterizing viscous effects and able to suppress structure formation at small scales, should appear from the dark coupling. At the level of the perturbations the analysis presented in this work reveals instead the difficulties in properly defining the dark sector interaction from a phenomenological perspective.

We report a systematic study on the directional sensitivity of a direct dark matter detector that detects the polar angle of a recoiling nucleus. A weakly interacting massive particle (WIMP)-mass independent method is used to obtain the sensitivity of a general detector in an isothermal galactic dark matter halo. By using two-dimensional distributions of energy and polar angle, a detector without head-tail information with 6.3 times the statistics is found to achieve the same performance level as a full three-dimensional tracking dark matter detector. Optimum operation orientations are obtained for various experimental configurations, with detectors that are space- or Earth-fixed, have head-tail capability or not, and use energy information or not. Earth-fixed detectors are found to have best sensitivity when the polar axis is oriented at a 45 degree angle from the Earth’s pole. With background contamination that mimics the WIMP signal’s energy distribution, the performance is found to decrease at a rate less than the decrease of signal purity. The WIMP-mass dependence of the performance of a detector with various energy thresholds that uses gaseous xenon as target material is reported. We find that with a $5\times {10}^{-46}{\mathrm{cm}}^2$ spin-independent WIMP-nucleon cross-section and a 30 GeV WIMP, a $770\mathrm{kg}·\mathrm{year}$’s exposure with a polar detector of 10 keV threshold can make a three sigma discovery of directional WIMPs in the isothermal galactic dark matter halo. For a columnar recombination detector, experimental considerations are discussed.

We analyze the clustering of a cosmic large scale structure using a consistent modified gravity perturbation theory, accounting for anisotropic effects along and transverse to the line of sight. The growth factor has a particular scale dependence in $f(R)$ gravity and we fit for the shape parameter $f_{R0}$ simultaneously with the distance and the large scale (general relativity) limit of the growth function. Using more than 690,000 galaxies in the baryon oscillation spectroscopy survey data release 11, we find no evidence for extra scale dependence, with the 95% confidence upper limit $|f_{R0}|<8\times 10^{-4}$. Future clustering data, such as from the dark energy spectroscopic instrument, can use this consistent methodology to impose tighter constraints.

Several baryons containing a heavy b-quark, the b-baryons, have been discovered. The charmless two-body decays of b-baryons can provide a new platform for $CP$ violating studies in a similar way provided by charmless two-body decays of B-meson. There are new $CP$ violating observables related to baryon polarization in b-baryon decays. We show that in the flavor $SU(3)$ limit, there exists relations involving different combinations of the decay amplitudes compared with those in $CP$ violating rate asymmetry. These new relations therefore provide interesting tests for the mechanism of $CP$ violations in the standard model (SM) and flavor $SU(3)$ symmetry. Such tests could complement the b-meson decay studies which hint at a better flavor $SU(3)$ conservation in b-hadron decays than in kaon and hyperon decays. Future data from LHCb can provide new information about $CP$ violation in the SM.

A novel model of spontaneous leptogenesis is investigated, where leptogenesis takes place in the thermal equilibrium due to a background Nambu-Goldstone field in motion. In particular, we identify the Nambu-Goldstone field to be the Majoron which associates with spontaneous breakdown of (discrete) $B-L$ symmetry. In this scenario sufficient lepton number asymmetry is generated in a primordial thermal bath without having $CP$-violating out-of-equilibrium decay of the heavy right-handed Majorana neutrinos. To obtain the observed baryon asymmetry, the neutrino masses are predicted in certain ranges, which can be translated into the effective mass of the neutrinoless double beta decay.

We investigate the prospects of indirect and direct dark matter searches within the minimal supersymmetric standard model with nine parameters (MSSM-9). These nine parameters include three gaugino masses, Higgs, slepton and squark masses, all treated independently. We perform a Bayesian Monte Carlo scan of the parameter space taking into consideration all available particle physics constraints such as the Higgs mass of 126 GeV, upper limits on the scattering cross section from direct-detection experiments, and assuming that the MSSM-9 provides all the dark matter abundance through a thermal freeze-out mechanism. Within this framework we find the two most probable regions for dark matter: 1-TeV Higgsino-like and 3-TeV Wino-like neutralinos. We discuss prospects for future indirect [in particular the Cherenkov Telescope Array (CTA)] and direct detection experiments. We find that for slightly contracted dark matter profiles in our Galaxy, which can be caused by the effects of baryonic infall in the Galactic center, CTA will be able to probe a large fraction of the remaining allowed region in synergy with future direct detection experiments like XENON-1T.