We present expected values of the single spin asymmetry in $D$-meson production in the process $p+p^{\uparrow }\to D^0+X$ at RHIC energy $(\sqrt{s}=200\mathrm{GeV})$ using a generalized parton model approach. For this purpose, we use the fits to the gluon Sivers function recently obtained by D’Alesio, Murgia, and Pisano. We find that the peak asymmetry predictions for these lie in a broad range, $0.5\%\lesssim A_N\lesssim 10\%$, for the kinematic regions considered. This is to be compared with the upper bound of 18% expected for the maximal gluon Sivers function. We extend our analysis to two other center-of-mass energies of proposed experiments: AFTER@LHC $(\sqrt{s}=115\mathrm{GeV})$ and a future RHIC run $(\sqrt{s}=500\mathrm{GeV})$. We further investigate (at $\sqrt{s}=200\mathrm{GeV}$) the effect of the transverse-momentum-dependent evolution of the unpolarized parton distribution functions and of the gluon Sivers function on the asymmetry predictions. We find that the inclusion of evolution causes an overall reduction of the asymmetry predictions. For example, predictions for the peak asymmetry decrease by a factor of 3 or more for the case of the saturated gluon Sivers function. This decrease is similar to that noticed earlier for single spin asymmetry in the electroproduction of $J/\psi$.

We discuss several possibilities to relate the $t$ dependence of generalized parton distributions to the distribution of angular momentum in the transverse plane. Using a simple spectator model, we demonstrate that none of them correctly describes the orbital angular momentum distribution that for a longitudinally polarized nucleon is obtained directly from light-front wave functions.

We determine the rates and energy and angular distributions of the positronium decays into a photon and a neutrino-antineutrino pair, $\mathrm{Ps}\to \gamma {\nu }_{\ell }{\overline{\nu }}_{\ell }$. We find that both positronium spin states have access to this decay channel, contrary to a previously published result. The low-energy tails of the spectra are shown to be sensitive to the binding effects and agree with Low’s theorem. Additionally, we find a connection between the behavior of the soft photon spectrum in both $\mathrm{o}\text{−}\mathrm{Ps}\to \gamma {\nu }_{\ell }{\overline{\nu }}_{\ell }$ and $\mathrm{o}\text{−}\mathrm{Ps}\to 3\gamma$ decays, and the Stark effect.

We argue that a natural boundary condition for gravity in asymptotically anti–de Sitter (AdS) spaces is to hold the renormalized boundary stress tensor density fixed, instead of the boundary metric. This leads to a well-defined variational problem, as well as new counterterms and a finite on-shell action. We elaborate this in various (even and odd) dimensions in the language of holographic renormalization. Even though the form of the new renormalized action is distinct from the standard one, once the cutoff is taken to infinity, their values on classical solutions coincide when the trace anomaly vanishes. For ${\mathrm{AdS}}_4$, we compute the Arnowitt-Deser-Misner form of this renormalized action and show in detail how the correct thermodynamics of Kerr-AdS black holes emerge. We comment on the possibility of a consistent quantization with our boundary conditions when the boundary is dynamical, and make a connection to the results of Compere and Marolf. The difference between our approach and microcanonical-like ensembles in standard AdS/CFT is emphasized.

We study quantum discord between two free modes of a massive scalar field in a maximally entangled state in de Sitter space. We introduce two observers, one in a global chart and the other in an open chart of de Sitter space, and the observers determine the quantum discord created by each detecting one of the modes. This situation is analogous to the relationship between an observer in a Minkowski chart and another in one of the two Rindler charts in flat space. We find that the state becomes less entangled as the curvature of the open chart gets larger. In particular, for the cases of a massless, and a conformally coupled scalar field, the entanglement vanishes in the limit of infinite curvature. However, we find that the quantum discord never disappears even in the limit that entanglement disappears.

It has been claimed that in a test of an asymptotically anti–de Sitter version of weak cosmic censorship conjecture by attempting to overspin a Bañados, Teitelboim, and Zanelli (BTZ) black hole with test particles, one finds that it is not possible to spin up the black hole past its extremal limit. The result of this analysis is restricted to the case where the initial black hole is extremal. We extend this analysis to find that massive test particles can overspin the black hole, if we start with a nearly extremal black hole, instead. We also consider the interaction of the BTZ black hole with test fields. We show that overspinning of nearly extremal black holes is possible whether or not there is super-radiance for the field. If there is super-radiance, overspinning occurs in a narrow range of frequencies bounded below by the super-radiant limit. However, if there is no super-radiance for the field, overspinning becomes generic and also applies to extremal black holes. This is in analogy with the Kerr case.

This paper derives accuracy standards for model gravitational waveforms required to ensure proper use of the Allen ${\chi }^2$ discriminator in gravitational wave data analysis. These standards are different from previously established requirements for detection and waveform parameter measurement based on signal-to-noise optimization. We present convenient formulas for evaluating and interpreting the contribution of model errors to measured values of this ${\chi }^2$ statistic. The new accuracy standards derived here are needed to ensure the reliability of measured values of the Allen ${\chi }^2$ statistic, both in their traditional role as vetoes and in their current role as elements in evaluating the significance of candidate detections.

The domain of outer communication of five-dimensional asymptotically flat stationary spacetimes may possess nontrivial 2-cycles (bubbles). Spacetimes containing such 2-cycles can have nonzero energy, angular momenta, and charge even in the absence of horizons. A mass variation formula has been established for spacetimes containing bubbles and possibly a black hole horizon. This “first law of black hole and soliton mechanics” contains new intensive and extensive quantities associated with each 2-cycle. We consider examples of such spacetimes for which we explicitly calculate these quantities and show how regularity is essential for the formulas relating them to hold. We also derive new explicit expressions for the angular momenta and charge for spacetimes containing solitons purely in terms of fluxes supporting the bubbles.

Scalar field self-force effects on a scalar charge orbiting a Reissner-Nordström black hole are investigated. The scalar wave equation is solved analytically in a post-Newtonian framework, and the solution is used to compute the self-field (up to 7.5 post-Newtonian order) as well as the components of the self-force at the particle’s location. The energy fluxes radiated to infinity and down the hole are also evaluated. Comparison with previous numerical results in the Schwarzschild case shows a reasonable agreement in both strong field and weak field regimes.

We present a general procedure for constructing exact black hole solutions with electric or magnetic charges in general relativity coupled to a nonlinear electrodynamics. We obtain a variety of two-parameter family spherically symmetric black hole solutions. In particular, the singularity at the center of the space-time can be canceled in the parameter space and the black hole solutions become regular everywhere in space-time. We study the global properties of the solutions and derive the first law of thermodynamics. We also generalize the procedure to include a cosmological constant and construct regular black hole solutions that are asymptotic to anti–de Sitter space-time.

In this paper, we study some classes of $\alpha$-attractor models in the Jordan frame, and we find the corresponding $F(R)$ gravity theory. We study analytically the problem at leading order, and we investigate whether the attractor picture persists in the $F(R)$ gravity equivalent theory. As we show, if the slow-roll conditions are assumed in the Jordan frame, the spectral index of primordial curvature perturbations and the scalar-to-tensor ratio are identical to the corresponding observational indices of the $R^2$ model, a result which indicates that the attractor property is also found in the corresponding $F(R)$ gravity theories of the $\alpha$-attractor models. Moreover, implicit and approximate forms of the $F(R)$ gravity inflationary attractors are found.

Moving from the consideration that matter fields must be treated in terms of their fundamental quantum counterparts, we show straightforward arguments, within the framework of ordinary quantum mechanics and quantum field theory, in order to convince readers that cosmological perturbations must be addressed in term of the semiclassical limit of the expectation value of quantum fields. We first take into account cosmological perturbations originated by a quantum scalar field, and then extend our treatment in order to account for the expectation values of bilinears of Dirac fermion fields. The latter can indeed transform as scalar quantities under diffeomorphisms, as well as all the other bilinear of the Dirac fields that belong to the Clifford algebra. This is the first of a series of works that is intended to prove that cosmological quantum perturbations can actually be accounted for in terms of Dirac fermion fields, which must be treated as fundamental quantum objects, and their dynamics.

We study whether it is possible to design a “classical” spatially flat bouncing cosmology or a static, spherically symmetric asymptotically flat Lorentzian wormhole in cubic Galileon theories interacting with an extra scalar field. We show that bouncing models are always plagued with gradient instabilities, while there are always ghosts in wormhole backgrounds.

In this paper we study the consequences of relaxing the hypothesis of the pressureless nature of the dark matter component when determining constraints on dark energy. To this aim we consider simple generalized dark matter models with constant equation of state parameter. We find that present-day low-redshift probes (type-Ia supernovae and baryonic acoustic oscillations) lead to a complete degeneracy between the dark energy and the dark matter sectors. However, adding the cosmic microwave background (CMB) high-redshift probe restores constraints similar to those on the standard $\mathrm{\Lambda }\mathrm{CDM}$ model. We then examine the anticipated constraints from the future Euclid survey on the same class of models, using a Fisher forecast estimation. We show that the Euclid survey allows us to break the degeneracy between the dark sectors, although the constraints on dark energy are much weaker than with standard dark matter. The use of CMB in combination allows us to restore the high precision on the dark energy sector constraints.

We study thermodynamic and transport properties for the isotropic color-spin-locking (iso-CSL) phase of two-flavor superconducting quark matter under compact star constraints within a Nambu-Jona-Lasinio-type chiral quark model. Chiral symmetry breaking and the phase transition to superconducting quark matter leads to a density dependent change of quark masses, chemical potentials, and diquark gap. A self-consistent treatment of these physical quantities influences the microscopic calculations of transport properties. We present results for the iso-CSL direct URCA emissivities and bulk viscosities, which fulfil the constraints on quark matter derived from cooling and rotational evolution of compact stars. We compare our results with the phenomenologically successful, but yet heuristic $2\mathrm{SC}+\mathrm{X}$ phase. We show that the microscopically founded iso-CSL phase can replace the purely phenomenological $2\mathrm{SC}+\mathrm{X}$ phase in modern simulations of the cooling evolution for compact stars with color-superconducting quark matter interior.

We show that a model with a scalar leptoquark of hypercharge $Y=1/6$ which includes light right-handed neutrinos can successfully describe both of the $B$-physics anomalies, $R_K^{\exp }<R_K^{\mathrm{SM}}$ and $R_D^{\exp }>R_D^{\mathrm{SM}}$. We discuss the corresponding low energy effective theory and, after using the known experimental data as constraints, we show that the model is viable and that it offers several predictions which can be tested experimentally.

In the presence of the Lorentz-violating $b^{\mu }$ coefficient, the spectra of bound states for a Dirac particle in a cylindric well are changed. Compared to the Lorentz invariant (LI) spectrum, the Lorentz violation deviation becomes significant when eigenenergy $E$ is sufficiently close to the critical values $\pm m$, where $m$ is the particle’s mass. The detailed profile of the deviation depends on the observer Lorentz nature of $b^{\mu }$. We discussed three types of $b^{\mu }$ configuration. When $b^{\mu }=(0,0,0,b_Z)$ is parallel to the well axis, the would be degenerate LI spectra split into two subspectra, reminiscent of the Zeeman splitting in the presence of a weak magnetic field. Depending on the relative sign of $b_Z$ accompanying mass $m$ in the dispersion relation, the spectrum extends or shrinks in the allowed eigenenergy region. When $b^{\mu }$ is a radial [$b^{\mu }=(0,b\cos \varphi ,b\sin \varphi ,0)$] or purely timelike vector [$b^{\mu }=(b^T,\overrightarrow{0})$], the spin-up and down components are coupled together, and there is no splitting. However, the monotonic increasing behavior of well depth $V_0$ with the decrease of eigenenergy $E$ is slightly changed when $E$ is sufficiently close to $-m$.

The hadronic decay widths and some ratios of branching fractions of the newly observed charmed strange baryons, ${\mathrm{\Xi }}_c(3055{)}^0$, ${\mathrm{\Xi }}_c(3055{)}^{+}$, and ${\mathrm{\Xi }}_c(3080{)}^{+}$ are calculated in a ${}^3{P}_0$ model. In the calculation, they are considered as 34 kinds of D-wave charmed strange baryons. Among these assignments, ${\mathrm{\Xi }}_c(3055{)}^{+}$ is very possibly a $J^P={\frac{5}{2}}^{+}$ ${\widehat{\mathrm{\Xi }}}_{c3}^{\prime }({\frac{5}{2}}^{+})$ or ${\check{\mathrm{\Xi }}}_{c3}^2({\frac{5}{2}}^{+})$. In these two assignments, ${\mathrm{\Xi }}_c(3055{)}^{+}$ has the total decay width $\mathrm{\Gamma }=10.1\mathrm{MeV}$ and $\mathrm{\Gamma }=7.6\mathrm{MeV}$, respectively. The predicted ratios $\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^{+}\to \mathrm{\Lambda }{D}^{+})/\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^{+}\to {\mathrm{\Sigma }}_c^{++}{K}^{-})=3.39$. ${\mathrm{\Xi }}_c(3055{)}^{+}$ is also very possibly a $J^P={\frac{7}{2}}^{+}$ ${\widehat{\mathrm{\Xi }}}_{c3}^{\prime }({\frac{7}{2}}^{+})$ or ${\check{\mathrm{\Xi }}}_{c3}^2({\frac{7}{2}}^{+})$. In these two assignments, ${\mathrm{\Xi }}_c(3055{)}^{+}$ has the total decay width $\mathrm{\Gamma }=9.7\mathrm{MeV}$ and $\mathrm{\Gamma }=6.3\mathrm{MeV}$, respectively. The predicted ratios $\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^{+}\to \mathrm{\Lambda }{D}^{+})/\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^{+}\to {\mathrm{\Sigma }}_c^{++}{K}^{-})=5.91$ or 6.04. As an isospin partner of ${\mathrm{\Xi }}_c(3055{)}^{+}$, ${\mathrm{\Xi }}_c(3055{)}^0$ is also very possibly a $J^P={\frac{5}{2}}^{+}$ ${\widehat{\mathrm{\Xi }}}_{c3}^{\prime }({\frac{5}{2}}^{+})$ or ${\check{\mathrm{\Xi }}}_{c3}^2({\frac{5}{2}}^{+})$. In these assignments, ${\mathrm{\Xi }}_c(3055{)}^0$ has the total decay width $\mathrm{\Gamma }=10.9\mathrm{MeV}$ and $\mathrm{\Gamma }=7.0\mathrm{MeV}$. The predicted ratios $\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^0\to \mathrm{\Lambda }{D}^0)/\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^0\to {\mathrm{\Sigma }}_c^{+}{K}^{-})=4.24$ or 4.20. ${\mathrm{\Xi }}_c(3055{)}^0$ is also very possibly a $J^P={\frac{7}{2}}^{+}$ ${\widehat{\mathrm{\Xi }}}_{c3}^{\prime }({\frac{7}{2}}^{+})$ or ${\check{\mathrm{\Xi }}}_{c3}^2({\frac{7}{2}}^{+})$. In these assignments, ${\mathrm{\Xi }}_c(3055{)}^0$ has the total decay width $\mathrm{\Gamma }=10.3\mathrm{MeV}$ and $\mathrm{\Gamma }=7.1\mathrm{MeV}$. The predicted ratios $\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^0\to \mathrm{\Lambda }{D}^0)/\mathrm{\Gamma }({\mathrm{\Xi }}_c(3055{)}^0\to {\mathrm{\Sigma }}_c^{+}{K}^{-})=7.47$ or 7.56. The results agree well with recent experimental data from Belle. ${\mathrm{\Xi }}_c(3080{)}^{+}$ seems impossible to identify with a D-wave charmed strange baryon.

We study the electromagnetic form factors of heavy flavored vector mesons such as $(D^{*},D_s^{*},J/\mathrm{\Psi })$, $(B^{*},B_s^{*},\mathrm{\Upsilon })$ via one photon radiative decays $(V\to P\gamma$) in the relativistic independent quark (RIQ) model based on a flavor independent average interaction potential in the scalar vector harmonic form. The momentum dependent spacelike $(q^2<0)$ form factors calculated in this model are analytically continued to the physical timelike region $0\le q^2\le (M_V-M_P{)}^2$. The predicted coupling constant $g_{VP\gamma }=F_{VP}(q^2=0)$ for real photon case in the limit $q^2\to 0$ and decay widths $\mathrm{\Gamma }(V\to P\gamma$) are found in reasonable agreement with experimental data and other model predictions.

The total cross sections are important ingredients for the current and future neutrino oscillation experiments. We present measurements of the total charged-current neutrino and antineutrino cross sections on scintillator (CH) in the NuMI low-energy beamline using an in situ prediction of the shape of the flux as a function of neutrino energy from 2–50 GeV. This flux prediction takes advantage of the fact that neutrino and antineutrino interactions with low nuclear recoil energy ($\nu$) have a nearly constant cross section as a function of incident neutrino energy. This measurement is the lowest energy application of the low-$\nu$ flux technique, the first time it has been used in the NuMI antineutrino beam configuration, and demonstrates that the technique is applicable to future neutrino beams operating at multi-GeV energies. The cross section measurements presented are the most precise measurements to date below 5 GeV.