We compute the transverse energy-energy correlation (EEC) and its asymmetry (AEEC) in next-to-leading order in ${\alpha }_s$ in proton-proton collisions at the LHC with the center-of-mass energy $E_{\mathrm{c}.\mathrm{m}.}=7\mathrm{TeV}$. We show that the transverse EEC and the AEEC distributions are insensitive to the QCD factorization and the renormalization scales, structure functions of the proton, and for a judicious choice of the jet size, also the underlying minimum bias events. Hence they can be used to precisely test QCD in hadron colliders and determine the strong coupling ${\alpha }_s$. We illustrate these features by defining the hadron jets using the anti-$k_T$ jet algorithm and an event selection procedure employed in the analysis of jets at the LHC and show the ${\alpha }_s(M_Z)$ dependence of the transverse EEC and the AEEC in the anticipated range $0.11\le {\alpha }_s(M_Z)\le 0.13$.

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of $5{\mathrm{fb}}^{-1}$ recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about $\pm 20\mathrm{GeV}$. These results significantly reduce the allowed parameter space for a fourth generation of fermions.

We demonstrate a first-principles analysis of the string theory landscapes in the framework of noncritical string/matrix models. In particular, we discuss nonperturbative instability, decay rate, and the true vacuum of perturbative string theories. As a simple example, we argue that the perturbative string vacuum of pure gravity is stable but that of Yang-Lee edge singularity is inescapably a false vacuum. Surprisingly, most perturbative minimal string vacua are unstable, and their true vacuum mostly does not suffer from nonperturbative ambiguity. Importantly, we observe that the instability of these tachyon-less closed string theories is caused by ghost D-instantons (or ghost ZZ-branes), the existence of which is determined only by nonperturbative completion of string theory.

Our previous results on the nonperturbative calculations of the mean current and of the energy-momentum tensor in QED with the $T$-constant electric field are generalized to arbitrary dimensions. The renormalized mean values are found, and the vacuum polarization contributions and particle creation contributions to these mean values are isolated in the large $T$ limit; we also relate the vacuum polarization contributions to the one-loop effective Euler-Heisenberg Lagrangian. Peculiarities in odd dimensions are considered in detail. We adapt general results obtained in $2+1$ dimensions to the conditions which are realized in the Dirac model for graphene. We study the quantum electronic and energy transport in the graphene at low carrier density and low temperatures when quantum interference effects are important. Our description of the quantum transport in the graphene is based on the so-called generalized Furry picture in QED where the strong external field is taken into account nonperturbatively; this approach is not restricted to a semiclassical approximation for carriers and does not use any statistical assumptions inherent in the Boltzmann transport theory. In addition, we consider the evolution of the mean electromagnetic field in the graphene, taking into account the backreaction of the matter field to the applied external field. We find solutions of the corresponding Dirac-Maxwell set of equations and with their help we calculate the effective mean electromagnetic field and effective mean values of the current and the energy-momentum tensor. The nonlinear and linear $I\mathrm{\text{−}}V$ characteristics experimentally observed in both low- and high-mobility graphene samples are quite well explained in the framework of the proposed approach, their peculiarities being essentially due to the carrier creation from the vacuum by the applied electric field.

This work deals with the presence of twinlike models in scalar field theories. We show how to build distinct scalar field theories having the same extended solution, with the same energy density and linear stability. Here, however, we start from a given but generalized scalar field theory, and we construct the corresponding twin model, which also engenders generalized dynamics. We investigate how the twinlike models arise in both flat and curved spacetimes. In the curved spacetime, we consider a braneworld model with the warp factor controlling the spacetime geometry with a single extra dimension of infinite extent. In particular, we study linear stability in both flat and curved spacetimes, and in the case of curved spacetime—in both the gravity and the scalar field sectors—for the two braneworld models.

The dense neutrino flux streaming from a core-collapse supernova can undergo self-induced flavor conversion caused by neutrino-neutrino refraction. Numerical studies of these nonlinear effects are challenging because representing the neutrino radiation field by discrete energy and angle bins can easily lead to unphysical solutions. In particular, if the number of angle bins $N_a$ is too small, flavor conversion begins too deep and produces completely spurious results. At the same time, $N_a=1$ (single-angle approximation) can be a good proxy for the $N_a\to \infty$ limit. Based on a linearized stability analysis, we explain some of the puzzling effects of discrete angle distributions.

We investigate the interiors of ($3+1$)-dimensional, asymptotically flat charged and rotating black holes as described by observers who fall into the black holes at late time, long after any perturbations of the exterior region have decayed. In the strict limit of late infall time, the initial experiences of such observers are precisely described by the region of the limiting stationary geometry to the past of its inner horizon. However, we argue that late-infall-time observers encounter a null shock wave at the location of the would-be outgoing inner horizon. In particular, for spherically symmetric black hole spacetimes, we demonstrate that freely falling observers experience a metric discontinuity across this shock; that is, a gravitational shock wave. Furthermore, the magnitude of this shock is at least of order unity. A similar phenomenon of metric discontinuity appears to take place at the inner horizon of a generically perturbed spinning black hole. We compare the properties of this null shock-wave singularity with those of the null weak singularity that forms at the Cauchy horizon.

The similarity between Finsler and Riemann geometry is an intriguing starting point to extend general relativity. The lack of quadratic restriction over the line element (color) naturally generalizes the Riemannian case and breaks the local symmetries of general relativity. In addition, the Finsler manifold is enriched with new geometric entities, and all the classical identities are suitably extended. We investigate the covariant kinematics of a medium formed by a timelike congruence. After a brief view in the general case, we impose particular geometric restrictions to get some analytic insight. A central role to our analysis plays the Lie derivative, where even in the case of irrotational Killing vectors the bundle still deforms. We demonstrate an example of an isotropic and exponentially expanding cross section that finally deflates or forms a caustic. Furthermore, using the $1+3$ covariant formalism we investigate the expansion dynamics of the congruence. For certain geometric restrictions we retrieve the Raychaudhuri equation where a color-curvature coupling is revealed. The condition to prevent the focusing of neighboring particles is given and is more likely to be fulfilled in highly curved regions. Then, we introduce the Levi-Civita connection for the osculating Riemannian metric and develop a (spatially) isotropic and homogeneous dustlike model with a nonsingular bounce.

We present updated predictions on the inclusive total cross sections, including the complete next-to-leading order QCD corrections, for the graviton and photon associated production process in the large extra dimensions model at the LHC with a center-of-mass energy of 7 and 8 TeV, using the parameters according to the requirements of the ATLAS and CMS Collaborations. Moreover, we also discuss in detail the dependence on the transverse momentum cut and uncertainties due to the choices of scales and parton distribution functions.

The discovery of a new neutral gauge boson $Z^{\prime }$ could provide the first concrete evidence of physics beyond the standard model. We explore how future parity violation experiments, especially atomic parity violation experiments, can be used to constrain $Z^{\prime }$ bosons. We use the recent measurement of the ${}^{133}\mathrm{Cs}$ nuclear weak charge to estimate lower bounds on the mass of $Z^{\prime }$ bosons for a number of representative models and to put constraints on the couplings of a newly discovered $Z^{\prime }$ boson. We also consider how these constraints might be improved by future atomic parity violation experiments that will measure nuclear weak charges of multiple isotopes. We show how measurements of a single isotope and combining measurements into ratios and differences can be used to constrain the couplings of a $Z^{\prime }$ and discriminate between models. We include in our results the constraints that can be obtained from the experiments Qweak and P2 that measure the proton weak charge. We find that current and future parity violation experiments could potentially play an important role in unravelling new physics if a $Z^{\prime }$ were discovered.

The impact of event color structure on the performance of the johns-hopkins, cms, heptoptagger and n-subjettiness algorithms is investigated by studying color singlet and color octet resonances decaying to top-quark pairs. Large differences in top-tagging efficiency are observed due to the different color charge of each resonance. These differences are quantified as a function of the algorithm parameters, the jet size parameter and the probability to misidentify light quarks and gluons as top candidates. We suggest that future experimental searches would benefit from optimizing the choice of algorithm parameters in order to minimize this source of model dependency.

We show that the observed pattern of quark flavor mixing, such as $|V_{us}|\simeq |V_{cd}|$, $|V_{cb}|\simeq |V_{ts}|$, $|V_{cd}/V_{td}|\simeq |V_{cs}/V_{ts}|\simeq |V_{tb}/V_{cb}|$, and $|V_{ub}/V_{cb}|<|V_{td}/V_{ts}|$, can essentially be understood in the chiral and heavy quark mass limits. In particular, the phenomenologically successful relations $|V_{ub}/V_{cb}|\sim \sqrt{m_u/m_c}$ and $|V_{td}/V_{ts}|\simeq \sqrt{m_d/m_s}$ can be reasonably conjectured in the $m_b\to \infty$ and $m_t\to \infty$ limits, respectively. We stress that the strength of weak $CP$ violation in the quark sector is determined by the moduli of the four corner elements of the Cabibbo-Kobayashi-Maskawa matrix. A comparison between strong and weak $CP$-violating effects in the standard model is also made.

We consider a generalized Brans-Dicke model in which the scalar field has a potential function and is also allowed to couple nonminimally with the matter sector. We assume a power-law form for the potential and the coupling functions as the inputs of the model and show that acceleration of the Universe can be realized for a constrained range of exponents of the potential function. We also argue that this accelerating phase is consistent with a large and positive Brans-Dicke parameter. In our analysis, the potential plays a more important role with respect to the coupling function in the dynamics of the Universe as the latter does not contribute to any of the relations characterizing evolution of the scale factor of the Universe and the scalar field. However, we will show that the coupling function is closely related to magnitude and direction of the energy transfer between matter and the scale field. We use this fact and some thermodynamic aspects of the model to put some constraints on the coupling function. In particular, we argue that the second law of thermodynamics constrains direction of the overall energy transfer.

We derive a massive analog of the Abraham-Lorentz-Dirac equation, i.e., the equation of motion of a relativistic charged particle with a radiation reaction term induced by emissions of massive fields. We show that the radiation reaction term has a nonanalytic behavior as a function of the mass $M$ of the radiation field and that both expansions with respect to $M$ and $1/M$ are generally invalid. Hence the massive Abraham-Lorentz-Dirac equation cannot be written as a local equation with derivative expansions. We especially investigate the radiation reaction in three specific motions: uniform acceleration, a circular motion, and a scattering process.

We provide a general formalism to calculate the infrared correlators of multiple interacting scalar fields in the de Sitter space by means of the stochastic approach. These scalar fields are treated as test fields, and hence our result is applicable to the models such as the curvaton scenario where the fields that yield initially isocurvature modes do not contribute to the cosmic energy density during inflationary expansion. The stochastic formalism combined with the argument of conformal invariance of the correlators reflecting the de Sitter isometries allows us to fix the form and amplitude of the three-point functions completely and partially for the four-point functions in terms of calculable quantities. It turns out that the naive scaling argument employed in the previous literature does not necessarily hold, and we derive the necessary and sufficient condition for the correlator to obey the naive scaling. We also find that correlation functions can, in principle, exhibit more complicated structure than argued in the literature.

Gravitational lensing of the cosmic microwave background (CMB) encodes cosmological information in the observed anisotropies of temperature and polarization. Accurate extraction of this additional information requires precise modeling of the covariance matrix of the power spectra of observed CMB fields. We introduce a new analytical model to describe the non-Gaussian structure of this covariance matrix and display the importance of second-order terms that were previously neglected. When compared with direct numerical simulations our model captures parameter errors to better than a few percent for cases where the non-Gaussianity causes an order unity degradation in errors. We also provide a detailed comparison between the information content of lensed CMB power spectra and ideal reconstruction of the lensing potential. We illustrate the impact of the non-Gaussian terms in the power spectrum covariance by providing Fisher errors on the sum of the masses of the neutrinos, the dark energy equation of state, and the curvature of the Universe.

Using detailed Monte Carlo simulations we have characterized the features of the radio emission of inclined air showers in the ultrahigh frequency band (300 MHz–3 GHz). The Fourier spectrum of the radiation is shown to have a sizable intensity well into the GHz frequency range. The emission is mainly due to transverse currents induced by the geomagnetic field and the excess charge produced by the Askaryan effect. At these frequencies only a significantly reduced volume of the shower around the axis contributes coherently to the signal observed on the ground. The size of the coherently emitting volume depends on frequency, shower geometry and observer position, and is interpreted in terms of the relative time delays at observation dominated by the curvature of the shower front. At ground level, the maximum emission at high frequencies is concentrated in an elliptical ringlike region around the intersection of a Cherenkov cone with its vertex at shower maximum and the ground. The frequency spectrum of inclined showers when observed at positions that view shower maximum in the Cherenkov direction, is shown to be in broad agreement with the pulses detected by the Antarctic Impulsive Transient Antenna experiment, making the interpretation that they are due to ultrahigh energy cosmic ray atmospheric showers consistent with our simulations. These results are also of great importance for experiments aiming to detect molecular bremsstrahlung radiation in the GHz range as they present an important background for its detection.

Big bang nucleosynthesis (BBN) is affected by the energy density of a primordial magnetic field (PMF). For an easy derivation of constraints on models for PMF generations, we assume a PMF with a power law (PL) distribution in wave number defined with a field strength, a PL index, and maximum and minimum scales at a generation epoch. We then show a relation between PL-PMF parameters and the scale invariant (SI) strength of PMF for the first time. We perform a BBN calculation including PMF effects, and show abundances as a function of baryon to photon ratio $\eta$. The SI strength of the PMF is constrained from observational constraints on abundances of ${}^4\mathrm{He}$ and D. The minimum abundance of ${}^7\mathrm{Li}/\mathrm{H}$ as a function of $\eta$ slightly moves to a higher ${}^7\mathrm{Li}/\mathrm{H}$ value at a larger $\eta$ value when a PMF exists during BBN. We then discuss degeneracies between the PL-PMF parameters in the PMF effect. In addition, we assume a general case in which both the existence and the dissipation of PMF are possible. It is then found that an upper limit on the SI strength of the PMF can be derived from a constraint on ${}^4\mathrm{He}$ abundance, and that a lower limit on the allowed ${}^7\mathrm{Li}$ abundance is significantly higher than those observed in metal-poor stars.

We investigate the phase transitions characterized by deconfinement and restoration of chiral and axial symmetries, at finite temperature, in the framework of QCD inspired models. We compare the results obtained in the SU(2) Polyakov–Nambu–Jona-Lasinio model with anomaly and in its extended version, the entangled Polyakov–Nambu–Jona-Lasinio model. In the last version, four-quark vertices with entanglement between the chiral condensate and the Polyakov loop are considered. The thermodynamics of the phase transitions, the meson spectrum, and in particular the convergence of axial and chiral partners, will be analyzed, as well as the topological susceptibility. We find that an explicit temperature dependence of the coupling vertices is necessary in both models in order to have effective restoration of the ${\mathrm{U}}_A(1)$ symmetry.

Assuming the newly observed resonant structures $X(1910)$, $X(2200)$, and $X(2350)$ as $\omega \omega$, $\omega \varphi$, and $\varphi \varphi$ molecular states, respectively, we compute their mass values in the framework of QCD sum rules. The numerical results are $1.97\pm 0.17\mathrm{GeV}$ for $\omega \omega$ state, $2.07\pm 0.21\mathrm{GeV}$ for $\omega \varphi$ state, and $2.18\pm 0.29\mathrm{GeV}$ for $\varphi \varphi$ state, which coincide with the experimental values of $X(1910)$, $X(2200)$, and $X(2350)$, respectively. This supports the statement that $X(1910)$, $X(2200)$, and $X(2350)$ could be $\omega \omega$, $\omega \varphi$, and $\varphi \varphi$ molecular candidates, respectively.