We introduce the use of the Weibull distribution as a simple parametrization of charged particle multiplicities in hadron-hadron collisions at all available energies, ranging from ISR energies to the most recent LHC energies. In statistics, the Weibull distribution has wide applicability in natural processes that involve fragmentation processes. This provides a natural connection to the available state-of-the-art models for multiparticle production in hadron-hadron collisions, which involve QCD parton fragmentation and hadronization. The Weibull distribution describes the multiplicity data at the most recent LHC energies better than the single negative binomial distribution.

The Bakamjian-Thomas relativistic quark model, describing hadrons with a fixed number of constituents, yields in the heavy quark limit of QCD covariant Isgur-Wise functions and satisfies the whole tower of lowest moment sum rules (Bjorken-Uraltsev type sum rules). We first recall, as well as earlier results, the new formalism presented in our recent papers on Lorentz representations, which provides an elegant framework for the analysis of this model in the heavy quark limit and stress the results which have been already obtained in this direction. Then, we give some very explicit demonstrations of the fact that the Bakamjian-Thomas framework satisfies the sum rules by considering simple cases of Isgur-Wise functions. In addition to the specific Bjorken and Uraltsev sum rules, an important sum rule that involves only heavy mesons with light cloud $j^P={\frac{1}{2}}^{-}$ and their radial excitations is demonstrated. This latter sum rule is phenomenologically interesting because it constrains the derivatives of the radially excited Isgur-Wise functions at zero recoil. On the other hand, we recall the limitations of the Bakamjian-Thomas scheme. At finite mass, current matrix elements with the current coupled to the heavy quark are no longer covariant, and higher moment sum rules that hold in the heavy quark limit of QCD are not satisfied.

The success of QCD factorization (QCDF) in predicting branching ratios for charmless $B$ decays to light pseudoscalar and vector mesons and the small $CP$ asymmetries measured at BABAR, Belle, and LHCb show that the phase in these decays, as predicted by QCDF, are not large. For a precise test of QCDF, one needs to extract from the measured decay rates the phase of the decay amplitude which appears in the interference terms between the tree and penguin contribution. Since the tree amplitude is known at the leading order in ${\mathrm{\Lambda }}_{\mathrm{QCD}}/m_b$ and is consistent with the measured tree-dominated decay rates, the QCDF value for the tree amplitude can be used with the measured decay rates to obtain the phases in $B\to K\pi$, $K\rho$, and $K^{*}\pi$ decay rates. This is similar to the extraction of the final-state interaction phases in the interference term between $p\overline{p}\to J/\mathrm{\Psi }\to e^{+}{e}^{-}$ and $p\overline{p}\to e^{+}{e}^{-}$ and in $J/\mathrm{\Psi }\to 0^{-}{0}^{-}$ done previously. In this paper, we present a determination of the phase between the $I=3/2$ tree and $I=1/2$ penguin amplitudes in $B\to K\pi$, $K\rho$, and $K^{*}\pi$ decays using the measured decay rates and the QCDF $I=3/2$ tree amplitude obtained from the $I=2B^{+}\to {\pi }^{+}{\pi }^0,{\rho }^0{\pi }^{+},{\rho }^{+}{\pi }^0$ tree-dominated decays and compare the result with the phase given by QCDF. It is remarkable that the phase extracted from experiments differs only slightly from the QCDF values. This shows that there is no large final-state interaction strong phase in $B\to K\pi$, $K\rho$, and $K^{*}\pi$ decays.

We consider the calculation of the pion-photon transition form factor $F^{{\gamma }^{*}\gamma {\pi }^0}(Q^2)$ within light-cone sum rules focusing attention to the low-mid region of momenta. The central aim is to estimate the theoretical uncertainties which originate from a wide variety of sources related to (i) the relevance of next-to-next-to-leading order radiative corrections (ii) the influence of the twist-four and the twist-six term (iii) the sensitivity of the results on auxiliary parameters, like the Borel scale $M^2$, (iv) the role of the phenomenological description of resonances, and (v) the significance of a small but finite virtuality of the quasireal photon. Predictions for $F^{{\gamma }^{*}\gamma {\pi }^0}(Q^2)$ are presented which include all these uncertainties and found to comply within the margin of experimental error with the existing data in the $Q^2$ range between 1 and $5{\mathrm{GeV}}^2$, thus justifying the reliability of the applied calculational scheme. This provides a solid basis for confronting theoretical predictions with forthcoming data bearing small statistical errors.

We present a new set of leading-twist parton distribution functions, referred to as “CJ15,” which take advantage of developments in the theoretical treatment of nuclear corrections as well as new data. The analysis includes, for the first time, data on the free neutron structure function from Jefferson Lab and new high-precision charged lepton and $W$-boson asymmetry data from Fermilab. These significantly reduce the uncertainty on the $d/u$ ratio at large values of $x$ and provide new insights into the partonic structure of bound nucleons.

Based on a sample of $(1310.6\pm 10.5)\times {10}^6$ $J/\psi$ events collected with the BESIII detector operating at the BEPCII storage ring, a partial wave analysis of the decay $J/\psi \to \gamma \varphi \varphi$ is performed in order to study the intermediate states. Results of the partial wave analysis show that the structures are predominantly $0^{-+}$ states. The existence of the $\eta (2225)$ is confirmed, and its resonance parameters are measured. Two additional pseudoscalar states, the $\eta (2100)$ with a mass of ${2050}_{-24-26}^{+30+75}\mathrm{MeV}/c^2$ and a width of ${250}_{-30-164}^{+36+181}\mathrm{MeV}/c^2$ and the $X(2500)$ with a mass of ${2470}_{-19-23}^{+15+101}\mathrm{MeV}/c^2$ and a width of ${230}_{-35-33}^{+64+56}\mathrm{MeV}/c^2$, are observed. In addition to these three pseudoscalar states, the scalar state $f_0(2100)$, and three tensor states, the $f_2(2010)$, $f_2(2300)$ and $f_2(2340)$, are observed in the process $J/\psi \to \gamma \varphi \varphi$. The product branching fractions $\mathcal{B}(J/\psi \to \gamma X)\times \mathcal{B}(X\to \varphi \varphi )$ are reported.

A search for a Higgs boson with suppressed couplings to fermions, $h_f$, assumed to be the neutral, lower-mass partner of the Higgs boson discovered at the Large Hadron Collider, is reported. Such a Higgs boson could exist in extensions of the standard model with two Higgs doublets, and could be produced via $p\overline{p}\to H^{\pm }{h}_f\to W^{*}{h}_f{h}_f\to 4\gamma +X$, where $H^{\pm }$ is a charged Higgs boson. This analysis uses all events with at least three photons in the final state from proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the Collider Detector at Fermilab, corresponding to an integrated luminosity of $9.2{\mathrm{fb}}^{-1}$. No evidence of a signal is observed in the data. Values of Higgs-boson masses between 10 and $100\mathrm{GeV}/c^2$ are excluded at 95% Bayesian credibility.

We have searched for the decay $B^0\to \varphi \gamma$ using the full Belle data set of $772\times {10}^6$ $B\overline{B}$ pairs collected at the $\mathrm{\Upsilon }(4\text{S})$ resonance with the Belle detector at the KEKB $e^{+}{e}^{-}$ collider. No signal is observed, and we set an upper limit on the branching fraction of $\mathcal{B}(B^0\to \varphi \gamma )<1.0\times {10}^{-7}$ at the 90% confidence level. This is the most stringent limit on this decay mode to date.

The entanglement exhibits extremal or singular behavior near quantum critical points (QCPs) in many condensed matter models. These intriguing phenomena, however, still call for a widely accepted understanding. In this paper we study this issue in holographic framework. We investigate the connection between the holographic entanglement entropy (HEE) and the quantum phase transition (QPT) in a lattice-deformed Einstein-Maxwell-Dilaton theory. Novel backgrounds exhibiting metal-insulator transitions (MIT) have been constructed in which both metallic phase and insulating phase have vanishing entropy density in zero temperature limit. We find that the first order derivative of HEE with respect to lattice parameters exhibits extremal behavior near QCPs. We propose that it would be a universal feature that HEE or its derivatives with respect to system parameters can characterize QPT in a generic holographic system. Our work opens a window for understanding the relation between entanglement and the QPT from a holographic perspective.

We explore $O(N)$ models in dimensions $4<d<6$. Specifically, we investigate models of an $O(N)$ vector field coupled to an additional scalar field via a cubic interaction. Recent results in $d=6-\epsilon$ have uncovered an interacting ultraviolet fixed point of the renormalization group (RG) if the number $N$ of components of the vector field is large enough, suggesting that these models are asymptotically safe. We set up a functional RG analysis of these systems to derive three key results. First, we find that in $d=5$ the interacting fixed point exists all the way down to $N=1$. Second, we show that the standard $O(N)$ universality classes are actually embedded in those of the cubic models, in that the latter exhibit the same values for (most of) the critical exponents, but feature an additional third RG relevant direction. Third, we address the critical question of global stability of the fixed-point potential to test whether the fixed point can underlie a viable quantum field theory.

We perform neutrino radiation-hydrodynamics simulations for the merger of asymmetric binary neutron stars in numerical relativity. Neutron stars are modeled by soft and moderately stiff finite-temperature equations of state (EOS). We find that the properties of the dynamical ejecta such as the total mass, neutron richness profile, and specific entropy profile depend on the mass ratio of the binary systems for a given EOS in a unique manner. For a soft EOS (SFHo), the total ejecta mass depends weakly on the mass ratio, but the average of electron number per baryon ($Y_e$) and specific entropy ($s$) of the ejecta decreases significantly with the increase of the degree of mass asymmetry. For a stiff EOS (DD2), with the increase of the mass asymmetry degree, the total ejecta mass significantly increases while the average of $Y_e$ and $s$ moderately decreases. We find again that only for the SFHo, the total ejecta mass exceeds $0.01M_{\odot }$ irrespective of the mass ratio chosen in this paper. The ejecta have a variety of electron number per baryon with an average approximately between $Y_e\sim 0.2$ and $\sim 0.3$ irrespective of the EOS employed, which is well suited for the production of the rapid neutron capture process heavy elements (second and third peaks), although its averaged value decreases with the increase of the degree of mass asymmetry.

Recently, motivated by certain loop quantum gravity-inspired corrections, it was shown that for spherically symmetric midisuperspace models infinitely many second-derivative theories of gravity exist (as revealed by the presence of three arbitrary functions in the corresponding Lagrangian/Hamiltonian) and not just those allowed by spherically symmetric general relativity. This freedom can be interpreted as the freedom to accommodate certain quantum gravity corrections in these models even in the absence of higher-curvature terms (at a semiclassical level, at least). For a particular choice of the arbitrary functions it is shown that the new theories map to spherically symmetric general relativity in arbitrary number of (integer) dimensions thus explicitly demonstrating that when working with midisuperspace models, one loses the information about the dimensionality of the full spacetime. In addition, it is shown that these new theories can accommodate scenarios of fractional spacetime dimensions as well as those of emergent spacetime dimensions—a possibility suggested by various approaches to quantum gravity.

The effective action of the recently proposed vector Galileon theory is considered. Using the background field method, we obtain the one-loop correction to the propagator of the Proca field from vector Galileon self-interactions. Contrary to the so-called scalar Galileon interactions, the two-point function of the vector field gets renormalized at the one-loop level, indicating that there is no nonrenormalization theorem in the vector Galileon theory. Using dimensional regularization, we remove the divergences and obtain the counterterms of the theory. The finite term is analytically calculated, which modifies the propagator and the mass term and generates some new terms also.

In the weak-field limit, analytic $f(R)$ models of gravity introduce a Yukawa-like correction to the Newtonian gravitational potential. These models have been widely tested at galactic scales and provide an alternative explanation to the dynamics of galaxies without Dark Matter. We study if the temperature anisotropies due to the thermal Sunyaev-Zeldovich effect are compatible with these extended theories of gravity. We assume that the gas is in hydrostatic equilibrium within the modified Newtonian potential and it is well described by a polytropic equation of state. We particularize the model for the Coma cluster and the predicted anisotropies are compared with those measured in the foreground cleaned maps obtained using the Planck Nominal maps released in 2013. We show that the computed $f(R)$ pressure profile fits the data, giving rise to competitive constraints of the Yukawa scale length $L=(2.19\pm 1.02)\mathrm{Mpc}$ and of the deviation parameter $\delta =-0.48\pm 0.22$. Those are currently the tightest constraints at galaxy cluster scale, and support the idea that extended theories of gravity provide an alternative explanation to the dynamics of self-gravitating systems without requiring dark matter.

We recall some well- and some lesser known results about the Kodama state and the related $\theta$ ambiguity in defining canonical variables. Based on them, we make some comments highlighting that the Kodama state for real connection variables can be given a precise meaning and that it implements a vacuum peaked on a (in a suitable sense) maximally symmetric geometry. We also highlight the similarity of this construction with the isolated horizon boundary condition $F\propto \mathrm{\Sigma }$ and stress that it is, in agreement with earlier work, inadequate to define the notion of a quantum horizon.

Using the Hilbert-Huang transform (HHT), we analyze gravitational waves from late inspiral, merger, and post-merger phases of binary neutron stars coalescence, computed by a general relativistic numerical simulation. The HHT analysis has been developed as a method for time series analysis of nonlinear and nonstationary data, and it enables us to perform a high resolution time frequency analysis of signals with strong frequency modulation by evaluating the instantaneous variation of amplitude and frequency of data. We find that we can clearly observe the time evolution of the instantaneous frequency of the post-merger waveforms. It is found that temporal variation of frequency of post-merger waveforms can be evaluated within 5% error if BNS coalescences occur within 10 Mpc. This accuracy allows us to constrain the equation of state of neutron stars and to evaluate the radius of a fiducial neutron star of $1.8M_{\odot }$ with a few hundred meters accuracy.

Gravitational wave searches for continuous-wave signals from neutron stars are especially challenging when the star’s spin frequency is unknown a priori from electromagnetic observations and wanders stochastically under the action of internal (e.g., superfluid or magnetospheric) or external (e.g., accretion) torques. It is shown that frequency tracking by hidden Markov model (HMM) methods can be combined with existing maximum likelihood coherent matched filters like the $\mathcal{F}$-statistic to surmount some of the challenges raised by spin wandering. Specifically, it is found that, for an isolated, biaxial rotor whose spin frequency walks randomly, HMM tracking of the $\mathcal{F}$-statistic output from coherent segments with duration $T_{\text{drift}}=10\mathrm{d}$ over a total observation time of $T_{\mathrm{obs}}=1\mathrm{yr}$ can detect signals with wave strains $h_0>2\times {10}^{-26}$ at a noise level characteristic of the Advanced Laser Interferometer Gravitational Wave Observatory (Advanced LIGO). For a biaxial rotor with randomly walking spin in a binary orbit, whose orbital period and semimajor axis are known approximately from electromagnetic observations, HMM tracking of the Bessel-weighted $\mathcal{F}$-statistic output can detect signals with $h_0>8\times {10}^{-26}$. An efficient, recursive, HMM solver based on the Viterbi algorithm is demonstrated, which requires $\sim {10}^3$ CPU hours for a typical, broadband (0.5-kHz) search for the low-mass x-ray binary Scorpius X-1, including generation of the relevant $\mathcal{F}$-statistic input. In a “realistic” observational scenario, Viterbi tracking successfully detects 41 out of 50 synthetic signals without spin wandering in stage I of the Scorpius X-1 Mock Data Challenge convened by the LIGO Scientific Collaboration down to a wave strain of $h_0=1.1\times {10}^{-25}$, recovering the frequency with a root-mean-square accuracy of $\le 4.3\times {10}^{-3}\mathrm{Hz}$.

Dark matter searches in gamma ray final states often make use of the fact that photons can be produced from final state muons. Modern Monte Carlo generators and dark matter codes include the effects of final state radiation from muons produced in the dark matter annihilation process itself, but neglect the $\mathcal{O}(1\%)$ radiative correction that arises from the subsequent muon decay. After implementing this correction we demonstrate the effect that it can have on dark matter phenomenology by considering the case of dark matter annihilation to four muons via scalar mediator production. We first show that the AMS-02 positron excess can no longer easily be made consistent with this final state once the Fermi-LAT dwarf limits are calculated with the inclusion of radiative muon decays, and we next show that the Fermi-LAT galactic center gamma excess can be improved with this final state after inclusion of the same effect. We provide code and tables for the implementation of this effect in the popular dark matter code micrOMEGAs, providing a solution for any model producing final state muons.