It has become customary to use a smoothing algorithm called “gradient flow” to fix the lattice spacing in a simulation, through a parameter called $t_0$. It is shown that, in order to keep the length $t_0$ fixed with respect to mesonic or gluonic observables as the number of colors $N_c$ is varied, the fiducial point for the flow parameter must be scaled nearly linearly in $N_c$. In simulations with dynamical fermions, the dependence of $t_0$ on the pseudoscalar meson mass flattens as the number of colors rises, in a way which is consistent with large $N_c$ expectations.

The lattice Dirac equation is formulated on a simplicial complex which approximates a smooth Riemann manifold by introducing a lattice vierbein on each site and a lattice spin connection on each link. Care is taken so the construction applies to any smooth D-dimensional Riemannian manifold that permits a spin connection. It is tested numerically in 2D for the projective sphere ${\mathbb{S}}^2$ in the limit of an increasingly refined sequence of triangles. The eigenspectrum and eigenvectors are shown to converge rapidly to the exact result in the continuum limit. In addition comparison is made with the continuum Ising conformal field theory on ${\mathbb{S}}^2$. Convergence is tested for the two point, $⟨\epsilon (x_1)\epsilon (x_2)⟩$, and the four point, $⟨\sigma (x_1)\epsilon (x_2)\epsilon (x_3)\sigma (x_4)⟩$, correlators for the energy, $\epsilon (x)=i\overline{\psi }(x)\psi (x)$, and twist operators, $\sigma (x)$, respectively.

The transport coefficients of quark matter at nonzero chemical potential and temperature are computed within the two-flavor Nambu–Jona-Lasinio model. We apply the Kubo formalism to obtain the thermal ($\kappa$) and electrical ($\sigma$) conductivities as well as an update of the shear viscosity ($\eta$) by evaluating the corresponding equilibrium two-point correlation functions to leading order in the $1/N_c$ expansion. The Dirac structure of the self-energies and spectral functions is taken into account as these are evaluated from the meson-exchange Fock diagrams for on-mass-shell quarks. We find that the thermal and electrical conductivities are decreasing functions of temperature and density above the Mott temperature $T_{\mathrm{M}}$ of dissolution of mesons into quarks, the main contributions being generated by the temporal and vector components of the spectral functions. The coefficients show a universal dependence on the ratio $T/T_{\mathrm{M}}$ for different densities, i.e., the results differ by a chemical-potential dependent constant. We also show that the Wiedemann-Franz law for the ratio $\sigma /\kappa$ does not hold. The ratio $\eta /s$, where $s$ is the entropy density, is of order of unity (or larger) close to the Mott temperature and, as the temperature increases, approaches the $\mathrm{AdS}/\mathrm{CFT}$ bound $1/4\pi$. It is also conjectured that the ratio $\kappa T/c_V$, with $c_V$ being the specific heat, is bounded from below by $1/18$.

We study the semi-inclusive limit of the deep inelastic scattering and Drell-Yan (DY) processes in soft collinear effective theory. In this regime so-called threshold logarithms must be resummed to render perturbation theory well behaved. Part of this resummation occurs via the Dokshitzer, Gribov, Lipatov, Altarelli, Parisi (DGLAP) equation, which at threshold contains a large logarithm that calls into question the convergence of the anomalous dimension. We demonstrate here that the problematic logarithm is related to rapidity divergences, and by introducing a rapidity regulator can be tamed. We show that resumming the rapidity logarithms allows us to reproduce the standard DGLAP running at threshold as long as a set of potentially large nonperturbative logarithms are absorbed into the definition of the parton distribution function (PDF). These terms could, in turn, explain the steep falloff of the PDF in the end point. We then go on to show that the resummation of rapidity divergences does not change the standard threshold resummation in DY, nor do our results depend on the rapidity regulator we choose to use.

We present a systematic investigation of the possible molecular states composed of a pair of doubly charmed baryons (${\mathrm{\Xi }}_{cc}{\mathrm{\Xi }}_{cc}$) or one doubly charmed baryon and one doubly charmed antibaryon $({\mathrm{\Xi }}_{cc}{\overline{\mathrm{\Xi }}}_{cc})$ within the framework of the one-boson-exchange-potential model. For the spin-triplet systems, we take into account the mixing between the ${{}^{3}S}_1$ and ${{}^{3}D}_1$ channels. For the baryon-baryon system ${\mathrm{\Xi }}_{cc}{\mathrm{\Xi }}_{cc}$ with $(R,I)=(\overline{3},1/2)$ and $(\overline{3},0)$, where $R$ and $I$ represent the group representation and the isospin of the system, respectively, there exist loosely bound molecular states. For the baryon-antibaryon system ${\mathrm{\Xi }}_{cc}{\overline{\mathrm{\Xi }}}_{cc}$ with $(R,I)=(8,1)$, $(8,1/2)$ and (8,0), there also exist deuteron-like molecules. The $B_{cc}{\overline{B}}_{cc}$ molecular states may be produced at LHC. The proximity of their masses to the threshold of two doubly charmed baryons provides a clean clue to identify them.

Three-body decay of charmed baryons ${\Lambda }_c^{*}(2595)$ and ${\Lambda }_c^{*}(2625)$ into ${\Lambda }_c\pi \pi$ are studied with effective Lagrangians in which the coupling constants are extracted from the nonrelativistic quark model. We take into account sequential processes going through ${\Sigma }_c(2455)$ and ${\Sigma }_c^{*}(2520)$ in intermediate states. The total decay widths are sensitive to the coupling of ${\Lambda }_c^{*}$ with ${\Sigma }_c\pi$ open channel and to ${\Sigma }_c^{*}\pi$ closed channel. We find that ${\Lambda }_c^{*}(2595)$ and ${\Lambda }_c^{*}(2625)$ with $\lambda$ mode assignment can explain the experimental data nicely. We also show invariant mass distributions of ${\Lambda }_c^{*}(2595)$ and ${\Lambda }_c^{*}(2625)$ decays, which are significantly different for various quark configurations.

The $P_c(4380)$ and $P_c(4450)$ states observed recently by the LHCb experiment were proposed to be either $\overline{D}{\mathrm{\Sigma }}_c^{*}$ or ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ bound states. We analyze the decay behaviors of two such 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 $\overline{D}{\mathrm{\Sigma }}_c^{*}$ molecule decays dominantly to the ${\overline{D}}^{*}{\mathrm{\Lambda }}_c$ channel with a branching ratio by 2 orders of magnitude larger than to $\overline{D}{\mathrm{\Lambda }}_c$, the ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ 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-${\frac{3}{2}}^{-}$ $\overline{D}{\mathrm{\Sigma }}_c^{*}$ molecule is about a factor of 2 larger than the corresponding value for the ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ molecule. It suggests that the assignment of the $\overline{D}{\mathrm{\Sigma }}_c^{*}$ molecule for $P_c(4380)$ is more favorable than the ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ molecule. In addition, $P_c(4450)$ seems to be a ${\overline{D}}^{*}{\mathrm{\Sigma }}_c$ molecule with $J^P={\frac{5}{2}}^{+}$ in our scheme. Based on these partial decay widths of the $P_c$ states, 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 $P_c$ states. The forthcoming $\gamma p$ experiment at JLAB and the $\pi p$ experiment at JPARC should be able to pin down the nature of these $P_c$ states.

Building on the analytical description of the post-merger (ringdown) waveform of coalescing, nonprecessing, spinning binary black holes introduced by Damour and Nagar [Phys. Rev. D 90, 024054 (2014)], we propose an analytic, closed form, time-domain, representation of the $\ell =m=2$ gravitational radiation mode emitted after merger. This expression is given as a function of the component masses and dimensionless spins $(m_{1,2},{\chi }_{1,2})$ of the two inspiraling objects, as well as of the mass $M_{\mathrm{BH}}$ and (complex) frequency ${\sigma }_1$ of the fundamental quasinormal mode of the remnant black hole. Our proposed template is obtained by fitting the post-merger waveform part of several publicly available numerical relativity simulations from the Simulating eXtreme Spacetimes (SXS) catalog and then suitably interpolating over (symmetric) mass ratio and spins. We show that this analytic expression accurately reproduces ($\sim 0.01\mathrm{rad}$) the phasing of the post-merger data of other data sets not used in its construction. This is notably the case of the spin-aligned run SXS:BBH:0305, whose intrinsic parameters are consistent with the 90% credible intervals reported in the parameter-estimation followup of GW150914 by B.P. Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016)]. Using SXS waveforms as “experimental” data, we further show that our template could be used on the actual GW150914 data to perform a new measure of the complex frequency of the fundamental quasinormal mode so as to exploit the complete (high signal-to-noise-ratio) post-merger waveform. We assess the usefulness of our proposed template by analyzing, in a realistic setting, SXS full inspiral-merger-ringdown waveforms and constructing posterior probability distribution functions for the central frequency damping time of the first overtone of the fundamental quasinormal mode as well as for the physical parameters of the systems. We also briefly explore the possibility opened by our waveform model to test the second law of black hole dynamics. Our model will help improve current tests of general relativity, in particular the general-relativistic no-hair theorem, and allow for novel tests, such as that of the area theorem.

Dwarf spheroidals are low-luminosity satellite galaxies of the Milky Way highly dominated by dark matter (DM). Therefore, they are prime targets to search for signals from dark matter annihilation using gamma-ray observations. While the typical assumption is that the dark matter density profile of these satellite galaxies can be described by a spherical symmetric Navarro-Frenk-White (NFW) profile, recent observational data of stellar kinematics suggest that the DM halos around these galaxies are better described by axisymmetric profiles. Motivated by such evidence, we analyze about seven  years of pass8 Fermi data for seven classical dwarf galaxies, including Draco, adopting both the widely used NFW profile and observationally motivated axisymmetric density profiles. For four of the selected dwarfs (Sextans, Carina, Sculptor and Fornax), axisymmetric mass models suggest a cored density profile rather than the commonly adopted cusped profile. We found that upper limits on the annihilation cross section for some of these dwarfs are significantly higher than the ones achieved using an NFW profile. Therefore, upper limits in the literature obtained using spherical symmetric cusped profiles, such as the NFW, might be overestimated. Our results show that it is extremely important to use observationally motivated density profiles going beyond the usually adopted NFW in order to obtain accurate constraints on the dark matter annihilation cross section.

The strong and radiative decay properties of the low-lying ${\mathrm{\Omega }}_c$ states are studied in a constituent quark model. We find that the newly observed ${\mathrm{\Omega }}_c$ states by the LHCb Collaboration can fit well in the decay patterns. Thus, their spin parity can possibly be assigned as the following: (i) ${\mathrm{\Omega }}_c(3000)$ has $J^P=1/2^{-}$ and corresponds to the narrow $1P$ mixed state $|1{{}^{2}P}_{\lambda }{\frac{1}{2}}^{-}{⟩}_1$; its partner $|1{{}^{2}P}_{\lambda }{\frac{1}{2}}^{-}{⟩}_2$ should be a broad state with a width of $\sim 100\mathrm{MeV}$. (ii) ${\mathrm{\Omega }}_c(3050)$ and ${\mathrm{\Omega }}_c(3066)$ can be assigned to be two $J^P=3/2^{-}$ states, $|1{{}^{4}P}_{\lambda }{\frac{3}{2}}^{-}⟩$ and $|1{{}^{2}P}_{\lambda }{\frac{3}{2}}^{-}⟩$, respectively. (iii) ${\mathrm{\Omega }}_c(3090)$ can be assigned as the $|1{{}^{4}P}_{\lambda }{\frac{5}{2}}^{-}⟩$ state with $J^P=5/2^{-}$. (iv) ${\mathrm{\Omega }}_c(3119)$ might correspond to one of the two $2S$ states of the first radial excitations, i.e., $|2{{}^{2}S}_{\lambda \lambda }{\frac{1}{2}}^{+}⟩$ or $|2{{}^{4}S}_{\lambda \lambda }{\frac{3}{2}}^{+}⟩$.

A wide variety of unified models predict asymptotic relations at $M_{\mathrm{GUT}}$ between the b quark and $\tau$ lepton Yukawa couplings. Within the framework of supersymmetric $\mathrm{SU}(4)\times {\mathrm{SU}(2)}_L\times {\mathrm{SU}(2)}_R$, we explore regions of the parameter space that are compatible with $\mathrm{b}\text{−}\tau$ quasi Yukawa Unification, Higgsinos being the lightest supersymmetric particles ($\lesssim 1\mathrm{TeV}$) accompanied by a relatively low level of fine-tuning determined by the parameter ${\mathrm{\Delta }}_{\mathrm{EW}}(\lesssim 200)$. Among the colored sparticles, the stop weighs more than 1.5 TeV or so, whereas the squarks of the first two families are significantly heavier, approaching 10 TeV in some cases. The gluino mass is estimated to lie in the 2–4 TeV range which raises the important question: Will the LHC find the gluino?

New hidden particles could potentially be emitted and discovered in rare nuclear transitions. In this work, we investigate the production of hidden vector bosons with primarily axial couplings to light quarks in nuclear transitions, and we apply our results to the recent anomaly seen in ${}^8\mathrm{Be}$ decays. The relevant matrix elements for ${{}^8\mathrm{Be}}^{*}(1^{+})\to {}^8\mathrm{Be}(0^{+})$ transitions are calculated using ab initio methods with internucleon forces derived from chiral effective field theory and the in-medium similarity renormalization group. We find that the emission of a light axial vector with mass $m_X\simeq 17\mathrm{MeV}$ can account for the anomaly seen in the $1^{+}\to 0^{+}$ isoscalar transition together with the absence of a significant anomaly in the corresponding isovector transition. We also show that such an axial vector can be derived from an anomaly-free ultraviolet-complete theory that is consistent with current experimental data.

The hypothesis that the QCD vacuum can be modeled as a dual superconductor is a powerful tool to describe the distribution of the color field generated by a quark-antiquark static pair and, as such, can provide useful clues for the understanding of confinement. In this work we investigate, by lattice Monte Carlo simulations of the $SU(3)$ pure gauge theory and of ($2+1$)-flavor QCD with physical mass settings, some properties of the chromoelectric flux tube at zero temperature and their dependence on the physical distance between the static sources. We draw some conclusions about the validity domain of the dual superconductor picture.

We present a calculation of the strange and charm quark contributions to the nucleon spin from the anomalous Ward identity (AWI). This is performed with overlap valence quarks on $2+1$-flavor domain-wall fermion gauge configurations on a $24^3\times 64$ lattice with lattice spacing $a^{-1}=1.73\mathrm{GeV}$ and the light sea mass at $m_{\pi }=330\mathrm{MeV}$. To satisfy the AWI, the overlap fermion for the pseudoscalar density and the overlap Dirac operator for the topological density, which do not have multiplicative renormalization, are used to normalize the form factor of the local axial-vector current at finite $q^2$. For the charm quark, we find that the negative pseudoscalar term almost cancels the positive topological term. For the strange quark, the pseudoscalar term is less negative than that of the charm. By imposing the AWI, the strange $g_A(q^2)$ at $q^2=0$ is obtained by a global fit of the pseudoscalar and the topological form factors, together with $g_A(q^2)$ and the induced pseudoscalar form factor $h_A(q^2)$ at finite $q^2$. The chiral extrapolation to the physical pion mass gives $\mathrm{\Delta }s+\mathrm{\Delta }\overline{s}=-0.0403(44)(78)$.

In the framework of open quantum systems, we analyze data from KamLAND by using a model that considers neutrino oscillation in a three-family approximation with the inclusion of the decoherence effect. Using a ${\chi }^2$ test, we find new limits for the decoherence parameter, which we call $\gamma$, considering the most recent data by KamLAND. Assuming an energy dependence of the type $\gamma ={\gamma }_0{(E/E_0)}^n$, at a 95% C.L., the limits found are $3.7\times {10}^{-24}\mathrm{GeV}$ for $n=-1$, $6.8\times {10}^{-22}\mathrm{GeV}$ for $n=0$, and $1.5\times {10}^{-19}\mathrm{GeV}$ for $n=1$ on the energy dependence.

Exact solutions describing the spherical collapse of null fluids can contain regions which violate the energy conditions. Physically the violations occur when the infalling matter continues to move inward even when nongravitational repulsive forces become stronger than gravity. In 1991 Ori proposed a resolution for these violations: spacetime surgery should be used to replace the energy condition violating region with an outgoing solution. The matter bounces. We revisit and implement this proposal for the more general Husain null fluids including a careful study of potential discontinuities and associated matter shells between the regions. Along the way we highlight an error in the standard classification of energy condition violations for type II stress-energy tensors.

We report a measurement of the power spectrum of cosmic microwave background (CMB) lensing from two seasons of Atacama Cosmology Telescope polarimeter (ACTPol) CMB data. The CMB lensing power spectrum is extracted from both temperature and polarization data using quadratic estimators. We obtain results that are consistent with the expectation from the best-fit Planck $\mathrm{\Lambda }\mathrm{CDM}$ model over a range of multipoles $L=80–2100$, with an amplitude of lensing $A_{\mathrm{lens}}=1.06\pm 0.15(\mathrm{stat})\pm 0.06(\mathrm{sys})$ relative to Planck. Our measurement of the CMB lensing power spectrum gives ${\sigma }_8{\mathrm{\Omega }}_m^{0.25}=0.643\pm 0.054$; including baryon acoustic oscillation scale data, we constrain the amplitude of density fluctuations to be ${\sigma }_8=0.831\pm 0.053$. We also update constraints on the neutrino mass sum. We verify our lensing measurement with a number of null tests and systematic checks, finding no evidence of significant systematic errors. This measurement relies on a small fraction of the ACTPol data already taken; more precise lensing results can therefore be expected from the full ACTPol data set.

We present constraints on the reheating era within the string fiber inflation scenario, in terms of the effective equation-of-state parameter of the reheating fluid, $w_{\mathrm{reh}}$. The results of the analysis, completely independent on the details of the inflaton physics around the vacuum, illustrate the behavior of the number of $e$-foldings during the reheating stage, $N_{\mathrm{reh}}$, and of the final reheating temperature, $T_{\mathrm{reh}}$, as functions of the scalar spectral index, $n_s$. We analyze our results with respect to the current bounds given by the Planck mission data and to upcoming cosmological experiments. We find that large values of the equation-of-state parameter ($w_{\mathrm{reh}}>1/3$) are particularly favored as the scalar spectral index is of the order of $n_s\sim 0.9680$, with a ${\sigma }_{n_s}\sim 0.002$ error. Moreover, we compare the behavior of the general reheating functions $N_{\mathrm{reh}}$ and $T_{\mathrm{reh}}$ in the fiber inflation scenario with the one extracted by the class of the $\alpha$-attractor models with $\alpha =2$. We find that the corresponding reheating curves are very similar in the two cases.

In the context of operator product expansion (OPE) and using the large-${\beta }_0$ approximation, we propose a method to define Wilson coefficients free from uncertainties due to IR renormalons. We first introduce a general observable $X(Q^2)$ with an explicit IR cutoff, and then we extract a genuine UV contribution $X_{\mathrm{UV}}$ as a cutoff-independent part. $X_{\mathrm{UV}}$ includes power corrections $\sim ({\mathrm{\Lambda }}_{\mathrm{QCD}}^2/Q^2{)}^n$ which are independent of renormalons. Using the integration-by-regions method, we observe that $X_{\mathrm{UV}}$ coincides with the leading Wilson coefficient in OPE and also clarify that the power corrections originate from UV region. We examine scheme dependence of $X_{\mathrm{UV}}$ and single out a specific scheme favorable in terms of analytical properties. Our method would be optimal with respect to systematicity, analyticity and stability. We test our formulation with the examples of the Adler function, QCD force between $Q\overline{Q}$, and $R$-ratio in $e^{+}{e}^{-}$ collision.

This paper is divided into two parts. In the first part, the material densities passed through for neutrinos going from FNAL to Sanford Laboratory are calculated using two recent density tables, Crustal [G. Laske, G. Masters, Z. Ma, and M. Pasyanos, Update on CRUST1.0—A 1-degree global model of Earth’s crust, Geophys. Res. Abstracts 15, EGU2013-2658 (2013),; For the programs and tables, see the website: http://igppweb.ucsd.edu/~gabi/crust1.html.] and Shen-Ritzwoller [W. Shen and M. H. Ritzwoller, Crustal and uppermost mantle structure beneath the United States, J. Geophys. Res.: Solid Earth 121, 4306 (2016)], as well as the values from an older table PEMC [A. M. Dziewonski, A. L. Hales, and E. R. Lapwood, Parametrically simple earth models consistent with geophysical data, Phys. Earth Plan. Int. 10, 12 (1975); For further information see the website: http://ds.iris.edu/ds/products/emc-pem/.]. In the second part, neutrino oscillations at Sanford Laboratory are examined for the variable density table of Shen-Ritzwoller. These results are then compared with oscillation results using the mean density from the Shen-Ritzwoller tables and with one other fixed density. For the tests made here, the mean density results are quite similar to the results using the variable density vs distance.