We perform a numerical study of the phase diagram of the model proposed in [M. Shifman, Phys. Rev. D 87, 025025 (2013).], which is a simple model containing non-Abelian vortices. As per the case of Abrikosov vortices, we map out a region of parameter space in which the system prefers the formation of vortices in ordered lattice structures. These are generalizations of Abrikosov vortex lattices with extra orientational moduli in the vortex cores. At sufficiently large lattice spacing the low energy theory is described by a sum of $CP(1)$ theories, each located on a vortex site. As the lattice spacing becomes smaller, when the self-interaction of the orientational field becomes relevant, only an overall rotation in internal space survives.

The tremendous progress in high-intensity laser technology and the establishment of dedicated high-field laboratories in recent years have paved the way towards a first observation of quantum vacuum nonlinearities at the high-intensity frontier. We advocate a particularly prospective scenario, where three synchronized high-intensity laser pulses are brought into collision, giving rise to signal photons, whose frequency and propagation direction differ from the driving laser pulses, thus providing various means to achieve an excellent signal to background separation. Based on the theoretical concept of vacuum emission, we employ an efficient numerical algorithm which allows us to model the collision of focused high-intensity laser pulses in unprecedented detail. We provide accurate predictions for the numbers of signal photons accessible in experiment. Our study is the first to predict the precise angular spread of the signal photons, and paves the way for a first verification of quantum vacuum nonlinearity in a well-controlled laboratory experiment at one of the many high-intensity laser facilities currently coming online.

We perform a comprehensive study of the time evolution of heavy-quarkonium states in an expanding hot QCD medium by implementing effective field theory techniques in the framework of open quantum systems. The formalism incorporates quarkonium production and its subsequent evolution in the fireball including quarkonium dissociation and recombination. We consider a fireball with a local temperature that is much smaller than the inverse size of the quarkonium and much larger than its binding energy. The calculation is performed at an accuracy that is leading order in the heavy-quark density expansion and next-to-leading order in the multipole expansion. Within this accuracy, for a smooth variation of the temperature and large times, the evolution equation can be written as a Lindblad equation. We solve the Lindblad equation numerically both for a weakly coupled quark-gluon plasma and a strongly coupled medium. As an application, we compute the nuclear modification factor for the $\mathrm{\Upsilon }(1S)$ and $\mathrm{\Upsilon }(2S)$ states. We also consider the case of static quarks, which can be solved analytically. Our study fulfills three essential conditions: it conserves the total number of heavy quarks, it accounts for the non-Abelian nature of QCD, and it avoids classical approximations.

We consider forward inclusive production of several quarks in the high energy $p\text{−}A$ collisions in the CGC formalism. For three particle production we provide a complete expression in terms of multipole scattering amplitudes on the nucleus and multiparticle generalized TMD’s of the proton. We then calculate all the terms that are not suppressed by the factor of the area in four particle production, and generalize this result up to terms of order $1/N_c^2$ for arbitrary number of produced particles. Our results include the contribution of quantum interference effects both in the final state radiation (HBT) and in the initial projectile wave function (Pauli blocking).

The tree-level $b\to c\ell {\overline{\nu }}_{\ell }$ based hadronic transitions have been the focus of much attention since recording significant deviations of the experimental data, on the ratios of the branching fractions in $\tau$ and $e-\mu$ channels of the semileptonic $B\to D$ transition, from the SM predictions by the BABAR Collaboration in 2012. It can be of great importance to look whether similar discrepancies take place in the semileptonic baryonic ${\mathrm{\Lambda }}_b\to {\mathrm{\Lambda }}_c\ell {\overline{\nu }}_{\ell }$ decay channel or not. In this accordance we estimate the decay width as well as the ratios of the branching fractions in $\tau$ and $e-\mu$ channels of this baryonic transition by calculating the form factors, entering the amplitude of this transition as the main inputs, in the framework of QCD sum rules in full theory. We compare the obtained results with the predictions of other theoretical studies. Our results may be compared with the corresponding future experimental data to look for possible deviations of data from the SM predictions.

We measure the inclusive production cross sections of hyperons and charmed baryons from $e^{+}{e}^{-}$ annihilation using a $800{\mathrm{fb}}^{-1}$ data sample taken near the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. The feed-down contributions from heavy particles are subtracted using our data, and the direct production cross sections are presented for the first time. The production cross sections divided by the number of spin states for $S=-1$ hyperons follow an exponential function with a single slope parameter except for the $\mathrm{\Sigma }(1385{)}^{+}$ resonance. Suppression for $\mathrm{\Sigma }(1385{)}^{+}$ and $\mathrm{\Xi }(1530{)}^0$ hyperons is observed. Among the production cross sections of charmed baryons, a factor of 3 difference for ${\mathrm{\Lambda }}_c^{+}$ states over ${\mathrm{\Sigma }}_c$ states is observed. This observation suggests a diquark structure for these baryons.

Using a data sample of $e^{+}{e}^{-}$ collision data with an integrated luminosity of $2.93{\mathrm{fb}}^{-1}$ taken at the center-of-mass energy $\sqrt{s}=3.773\mathrm{GeV}$ with the BESIII detector operating at the BEPCII storage rings, we measure the absolute branching fractions of the two-body hadronic decays $D^{+}\to {\pi }^{+}{\pi }^0$, $K^{+}{\pi }^0$, ${\pi }^{+}\eta$, $K^{+}\eta$, ${\pi }^{+}{\eta }^{\prime }$, $K^{+}{\eta }^{\prime }$, $K_S^0{\pi }^{+}$, $K_S^0{K}^{+}$, and $D^0\to {\pi }^{+}{\pi }^{-}$, $K^{+}{K}^{-}$, $K^{\mp }{\pi }^{\pm }$, $K_S^0{\pi }^0$, $K_S^0\eta$, $K_S^0{\eta }^{\prime }$. Our results are consistent with previous measurements within uncertainties. Among them, the branching fractions for $D^{+}\to {\pi }^{+}{\pi }^0$, $K^{+}{\pi }^0$, ${\pi }^{+}\eta$, ${\pi }^{+}{\eta }^{\prime }$, $K_S^0{\pi }^{+}$, $K_S^0{K}^{+}$ and $D^0\to K_S^0{\pi }^0$, $K_S^0\eta$, $K_S^0{\eta }^{\prime }$ are determined with improved precision compared to the world average values.

A search for the associated production of the Higgs boson with a top quark pair ($t\overline{t}H$) is reported. The search is performed in multilepton final states using a data set corresponding to an integrated luminosity of $36.1{\mathrm{fb}}^{-1}$ of proton-proton collision data recorded by the ATLAS experiment at a center-of-mass energy $\sqrt{s}=13\mathrm{TeV}$ at the Large Hadron Collider. Higgs boson decays to $W{W}^{*}$, $\tau \tau$, and $Z{Z}^{*}$ are targeted. Seven final states, categorized by the number and flavor of charged-lepton candidates, are examined for the presence of the Standard Model Higgs boson with a mass of 125 GeV and a pair of top quarks. An excess of events over the expected background from Standard Model processes is found with an observed significance of 4.1 standard deviations, compared to an expectation of 2.8 standard deviations. The best fit for the $t\overline{t}H$ production cross section is $\sigma (t\overline{t}H)=790_{-210}^{+230}\mathrm{fb}$, in agreement with the Standard Model prediction of $507_{-50}^{+35}\mathrm{fb}$. The combination of this result with other $t\overline{t}H$ searches from the ATLAS experiment using the Higgs boson decay modes to $b\overline{b}$, $\gamma \gamma$ and $Z{Z}^{*}\to 4\ell$, has an observed significance of 4.2 standard deviations, compared to an expectation of 3.8 standard deviations. This provides evidence for the $t\overline{t}H$ production mode.

The observations of gravitational waves from the binary neutron star merger event GW170817 and the subsequent observation of its electromagnetic counterparts from the gamma-ray burst GRB 170817A provide us a significant opportunity to study theories of gravity beyond general relativity. An important outcome of these observations is that they constrain the difference between the speed of gravity and the speed of light to less than ${10}^{-15}c$. Also, the time delay between the arrivals of gravitational waves at different detectors constrains the speed of gravity at the Earth to be in the range $0.55c<v_{gw}<1.42c$. We use these results to constrain a widely studied modified theory of gravity: Eddington-inspired Born-Infeld (EiBI) gravity. We show that, in EiBI theory, the speed of gravitational waves in matter deviates from $c$. From the time delay in the arrival of gravitational wave signals at Earth-based detectors, we obtain the bound on the theory parameter $\kappa$ as $|\kappa |\lesssim {10}^{21}{\mathrm{m}}^2$. Similarly, from the time delay between the signals of GW170817 and GRB 170817A, in a background Friedmann-Robertson-Walker universe, we obtain $|\kappa |\lesssim {10}^{37}{\mathrm{m}}^2$. Although the bounds on $\kappa$ are weak compared to other earlier bounds from the study of neutron stars, stellar evolution, primordial nucleosynthesis, etc., our bounds are from direct observations and thus worth noting.

In the present study, we consider an extended form of teleparallel Lagrangian $f(T,\varphi ,X)$, as function of a scalar field $\varphi$, its kinetic term $X$ and the torsion scalar $T$. We use linear perturbations to obtain the equation of matter density perturbations on sub-Hubble scales. The gravitational coupling is modified in scalar modes with respect to the one of general relativity, albeit vector modes decay and do not show any significant effects. We thus extend these results by involving multiple scalar field models. Further, we study conformal transformations in teleparallel gravity and we obtain the coupling as the scalar field is nonminimally coupled to both torsion and boundary terms. Finally, we propose the specific model $f(T,\varphi ,X)=T+{\partial }_{\mu }\varphi {\partial }^{\mu }\varphi +\xi T{\varphi }^2$. To check its goodness, we employ the observational Hubble data, constraining the coupling constant, $\xi$, through a Monte Carlo technique based on the Metropolis-Hastings algorithm. Hence, fixing $\xi$ to its best-fit value got from our numerical analysis, we calculate the growth rate of matter perturbations and we compare our outcomes with the latest measurements and the predictions of the $\mathrm{\Lambda }\mathrm{CDM}$ model.

If the symmetry breaking responsible for axion dark matter production occurs during the radiation-dominated epoch in the early Universe, then this produces large amplitude perturbations that collapse into dense objects known as axion miniclusters. The characteristic minicluster mass, $M_0$, is set by the mass inside the horizon when axion oscillations begin. For the QCD axion $M_0\sim {10}^{-10}{M}_{\odot }$, however, for an axionlike particle, $M_0$ can approach $M_{\odot }$ or higher. Using the Press-Schechter formalism we compute the mass function of halos formed by hierarchical structure formation from these seeds. We compute the concentrations and collapse times of these halos and show that they can grow to be as massive as $10^6{M}_0$. Within the halos, miniclusters likely remain tightly bound, and we compute their gravitational microlensing signal taking the fraction of axion dark matter collapsed into miniclusters, $f_{\mathrm{MC}}$, as a free parameter. A large value of $f_{\mathrm{MC}}$ severely weakens constraints on axion scenarios from direct detection experiments. We take into account the non-Gaussian distribution of sizes of miniclusters and determine how this affects the number of microlensing events. We develop the tools to consider microlensing by an extended mass function of nonpointlike objects, and we use microlensing data to place the first observational constraints on $f_{\mathrm{MC}}$. This opens a new window for the potential discovery of the axion.

We present a comprehensive renormalization group analysis of the littlest seesaw model involving two right-handed neutrinos and a very constrained Dirac neutrino Yukawa coupling matrix. We perform the first ${\chi }^2$ analysis of the low energy masses and mixing angles, in the presence of renormalization group corrections, for various right-handed neutrino masses and mass orderings, both with and without supersymmetry. We find that the atmospheric angle, which is predicted to be near maximal in the absence of renormalization group corrections, may receive significant corrections for some nonsupersymmetric cases, bringing it into close agreement with the current best fit value in the first octant. By contrast, in the presence of supersymmetry, the renormalization group corrections are relatively small, and the prediction of a near maximal atmospheric mixing angle is maintained, for the studied cases. Forthcoming results from T2K and $\mathrm{NO}\nu \mathrm{A}$ will decisively test these models at a precision comparable to the renormalization group corrections we have calculated.

We investigate possible interactions between neutrinos and massive scalar bosons via $g_{\varphi }\overline{\nu }\nu \varphi$ (or massive vector bosons via $g_V\overline{\nu }{\gamma }^{\mu }\nu V_{\mu }$) and explore the allowed parameter space of the coupling constant $g_{\varphi }$ (or $g_V$) and the scalar (or vector) boson mass $m_{\varphi }$ (or $m_V$) by requiring that these secret neutrino interactions (SNIs) should not spoil the success of big bang nucleosynthesis (BBN). Incorporating the SNIs into the evolution of the early Universe in the BBN era, we numerically solve the Boltzmann equations and compare the predictions for the abundances of light elements with observations. It turns out that the constraint on $g_{\varphi }$ and $m_{\varphi }$ in the scalar-boson case is rather weak, due to a small number of degrees of freedom (d.o.f.). However, in the vector-boson case, the most stringent bound on the coupling $g_V\lesssim 6\times {10}^{-10}$ at 95% confidence level is obtained for $m_V\simeq 1\mathrm{MeV}$, while the bound becomes much weaker $g_V\lesssim 8\times {10}^{-6}$ for smaller masses $m_V\lesssim {10}^{-4}\mathrm{MeV}$. Moreover, we discuss in some detail how the SNIs affect the cosmological evolution and the abundances of the lightest elements.

We investigate asymptotic safety of a toy model of a singlet-scalar extension of the Higgs sector including two real scalar fields under the impact of quantum-gravity fluctuations. Employing functional renormalization group techniques, we search for fixed points of the system which provide a tentative ultraviolet completion of the system. We find that in a particular regime of the gravitational parameter space the canonically marginal and relevant couplings in the scalar sector—including the mass parameters—become irrelevant at the ultraviolet fixed point. The infrared potential for the two scalars that can be reached from that fixed point is fully predicted and features no free parameters. In the remainder of the gravitational parameter space, the values of the quartic couplings in our model are predicted. In light of these results, we discuss whether the singlet-scalar could be a dark-matter candidate. Furthermore, we highlight how “classical scale invariance” in the sense of a flat potential of the scalar sector at the Planck scale could arise as a consequence of asymptotic safety.

We discuss the quantization of linearized gravity in the background de Sitter spacetime using a gauge-invariant formalism to write the perturbed gravitational field in the static patch. This field is quantized after fixing the gauge completely. The response rate of this field to monochromatic multipole sources is then computed in the thermal equilibrium state with the well-known Gibbons-Hawking temperature. We compare this response rate with the one obtained in the Bunch-Davies-like vacuum state defined in the Poincaré patch. These response rates are found to be the same as expected. This agreement serves as a verification of the infrared finite graviton two-point function in the static patch of de Sitter spacetime found previously.

We introduce a new geometrically invariant prescription for comparing two different spacetimes based on geodesic deviation. We use this method to compare a family of recently introduced analytical spacetime representing inspiraling black-hole binaries to fully nonlinear numerical solutions to the Einstein equations. Our method can be used to improve analytical spacetime models by providing a local measure of the effects that violations of the Einstein equations will have on timelike geodesics, and indirectly, gas dynamics. We also discuss the advantages and limitations of this method.

Will [Astrophys. J. 191, 521 (1974)] solved the perturbation of a Schwarzschild black hole due to a slowly rotating light concentric thin ring, using Green’s functions expressed as infinite-sum expansions in multipoles and in the small mass and rotational parameters. In a previous paper [P. Čížek and O. Semerák, Astrophys. J. Suppl. Ser. 232, 14 (2017)], we expressed the Green functions in closed form containing elliptic integrals, leaving just summation over the mass expansion. Such a form is more practical for numerical evaluation, but mainly for generalizing the problem to extended sources where the Green functions have to be integrated over the source. We exemplified the method by computing explicitly the first-order perturbation due to a slowly rotating thin disc lying between two finite radii. After finding basic parameters of the system—mass and angular momentum of the black hole and of the disc—we now add further properties, namely those which reveal how the disc gravity influences geometry of the black-hole horizon and those of circular equatorial geodesics (specifically, radii of the photon, marginally bound and marginally stable orbits). We also realize that, in the linear order, no ergosphere occurs and the central singularity remains pointlike, and check the implications of natural physical requirements (energy conditions and subluminal restriction on orbital speed) for the single-stream as well as counter-rotating double-stream interpretations of the disc.

We study the generation of helical magnetic fields in a model of inflationary magnetogenesis which is free from the strong coupling and backreaction problems. To generate helical magnetic fields, we add an $f^2{\tilde{F}}^{\mu \nu }{F}_{\mu \nu }$ term to the Lagrangian of the Ratra model. The strong coupling and backreaction problems are avoided if we take a particular behavior of coupling function $f$, in which $f$ increases during inflation and decreases postinflation to reheating. The generated magnetic field is fully helical and has a blue spectrum, $d{\rho }_B/d\ln k\propto k^4$. This spectrum is obtained when coupling function $f\propto a^2$ during inflation. The scale of reheating in our model has to be lower than 4000 GeV to avoid backreaction postinflation. The generated magnetic field spectrum satisfies the $\gamma$-ray bound for all the possible scales of reheating. The comoving magnetic field strength and its correlation length are $\sim 4\times {10}^{-11}\mathrm{G}$ and 70 kpc respectively, if reheating takes place at 100 GeV. For reheating at the QCD scales of 150 MeV, the field strength increases to $\sim$ nano gauss, with coherence scale of 0.6 Mpc.

Neutrinos from supernovae (SNe) are crucial probes of explosive phenomena at the deaths of massive stars and neutrino physics. High-energy neutrinos are produced through hadronic processes by cosmic rays, which are accelerated during interaction between the supernova (SN) ejecta and circumstellar material (CSM). Recent observations of extragalactic SNe have revealed that a dense CSM is commonly expelled by the progenitor star. We provide new quantitative predictions of time-dependent high-energy neutrino emission from diverse types of SNe. We show that IceCube and KM3Net can detect $\sim {10}^3$ events from a SN II-P (and $\sim 3\times {10}^5$ events from a SN IIn) at a distance of 10 kpc. The new model also enables us to critically optimize the time window for dedicated searches for nearby SNe. A successful detection will give us a multienergy neutrino view of SN physics and new opportunities to study neutrino properties, as well as clues to the cosmic-ray origin. GeV-TeV neutrinos may also be seen by KM3Net, Hyper-Kamiokande, and PINGU.

We study the low-virtuality inclusive leptoproduction of open charm, $p^{\uparrow }l\to D^0+X$ as a probe of the gluon Sivers function. We perform the analysis in a generalized parton model framework. At leading order, this process is sensitive only to the gluon content of the proton. Hence any detection of a transverse single-spin asymmetry in this process would be clear indication of a non-zero gluon Sivers function (GSF). Considering COMPASS and a future Electron-Ion Collider (EIC), we present predictions for asymmetry using fits for the GSF available in literature. Predictions for peak asymmetry values lie in the range of 0.8% to 13%. We also present estimates of the upper bound on the asymmetry as obtained with a maximal gluon Sivers function. Further, for the case of the Electron-Ion Collider, we evaluate the asymmetry in the muons decaying from the $D$-meson and find that the asymmetry is well preserved in the kinematics of the muons. Peak values of the muon asymmetry are close to those obtained for the $D$-meson and lie in the range 0.75% to 11%.