Recently a new bosonization method has been used to derive, at zero fermion density, an effective action for relativistic field theories whose partition function is dominated by fermionic composites, chiral mesons in the case of QCD. This approach shares two important features with variational methods: the restriction to the subspace of the composites, and the determination of their structure functions by a variational calculation. But unlike standard variational methods it treats excited states on the same footing as the ground state. I show that this bosonization method is an approximation of an exact procedure in which composites are introduced in the presence of fermionic states with the quantum numbers of the constituents (quasiparticles). This procedure consists of an independent Bogoliubov transformation at each time slice. The time-dependent parameters of the transformation are then associated with composite fields. In this way states of nonvanishing fermion (baryon) number (neglected in the bosonization approach) are retained. By the exact procedure I derive an effective action for QCD at finite temperature and baryon density. I test the result on a four-fermion interaction model.

We study the production of electroweak gauge bosons at high energies in the framework of $k_T$-factorization QCD approach. The amplitude for production of a single $W^{\pm }$ or $Z^0$ boson associated with quark pair in the fusion of two off-shell gluons is calculated. Contributions from the valence quarks are calculated using the quark-gluon interaction and quark-antiquark annihilation QCD subprocesses. The total and differential cross sections (as a function of the transverse momentum and rapidity) are presented and the ratio of cross sections for $W^{\pm }$ and $Z^0$ boson production is investigated. The conservative error analysis is performed. In the numerical calculations two different sets of unintegrated gluon distributions in the proton are used: the one obtained from the Ciafaloni-Catani-Fiorani-Marchesini evolution equation and the other from the Kimber-Martin-Ryskin prescription. Theoretical results are compared with experimental data taken by the D0 and CDF collaborations at the Tevatron. We demonstrate the importance of the quark component in parton evolution in description of the experimental data. This component is very significant also at the LHC energies.

We formulate the single transverse spin asymmetry in heavy quarkonium production in lepton-nucleon and nucleon-nucleon collisions in the nonrelativistic limit. We find that the asymmetry is very sensitive to the production mechanism. The final state interactions with the heavy quark and antiquark cancel out among themselves when the pair are produced in a color-singlet configuration, or cancel out with the initial state interaction in $pp$ scattering when they are in color-octet. As a consequence, the asymmetry is nonzero in $ep$ collisions only in the color-octet model, whereas in $pp$ collisions only in the color-singlet model.

We report the results of a search for the anomalous production of a massive particle decaying to four electrons via two $Z^0$ bosons in $1.1{\mathrm{fb}}^{-1}$ of $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ collected by the CDF II detector at Fermilab. We employ optimized electron identification criteria to maximize acceptance and efficiency. We estimate the backgrounds in the invariant mass range $500–1000\mathrm{GeV}/c^2$ to be $0.028\pm 0.009(\mathrm{stat})\pm 0.011(\mathrm{syst})$ events. We observe zero events in this search region. Assuming a Randall-Sundrum graviton production model, we set 95% C.L. limits on $\sigma \times \mathrm{BF}(G\to Z^0{Z}^0)<4–6\mathrm{pb}$, depending on the graviton mass.

We present the dominant two-loop electroweak corrections to the partial decay widths to gluon jets and prompt photons of the neutral $CP$-odd Higgs boson $A^0$, with mass $M_{A^0}<2M_W$, in the two-Higgs-doublet model for low to intermediate values of the ratio $\tan \beta =v_2/v_1$ of the vacuum expectation values. They apply as they stand to the production cross sections in hadronic and two-photon collisions, at the Tevatron, the LHC, and a future photon collider. The appearance of three ${\gamma }_5$ matrices in closed fermion loops requires special care in the dimensional regularization of ultraviolet divergences, and the finite electroweak renormalization of the pseudoscalar current restoring the anticommutativity of ${\gamma }_5$ is performed for the first time. The corrections are negative and amount to several percent, so that they fully compensate or partly screen the enhancement due to QCD corrections.

We present formulas for the coefficients of 2-, 3-, 4-, and 5-point master integrals for one-loop massive amplitudes. The coefficients are derived from unitarity cuts in $D$ dimensions. The input parameters can be read off from any unitarity-cut integrand, as assembled from tree-level expressions, after simple algebraic manipulations. The formulas presented here are suitable for analytical as well as numerical evaluation. Their validity is confirmed in two known cases of helicity amplitudes contributing to $gg\to gg$ and $gg\to gH$, where the masses of the Higgs and the fermion circulating in the loop are kept as free parameters.

We provide predictions for the rapidity distributions of exclusive photoproduced $J/\psi$ and ${\rm Y}$ mesons, and $Z^0$ bosons, at the Tevatron and Large Hadron Collider. We use the equivalent-photon approximation with the photon-proton cross sections given by the impact parameter dependent dipole saturation model, which has already been shown to give a good description of a wide variety of HERA data. We derive the quark-antiquark light-cone wave functions of timelike neutral electroweak bosons. An essential difference is pointed out between the amplitude for timelike heavy boson photoproduction and the amplitude for deeply virtual Compton scattering.

We discuss the role of so-called “intrinsic-charm” operators in semileptonic $B$-meson decays, which appear first at order $1/m_b^3$ in the heavy quark expansion. We show by explicit calculation that—at scales $\mu \le m_c$—the contributions from “intrinsic-charm” effects can be absorbed into short-distance coefficient functions multiplying, for instance, the Darwin term. Then, the only remnant of “intrinsic charm” are logarithms of the form $\ln (m_c^2/m_b^2)$, which can be resummed by using renormalization-group techniques. As long as the dynamics at the charm-quark scale is perturbative, ${\alpha }_s(m_c)\ll 1$, this implies that no additional nonperturbative matrix elements aside from the Darwin and the spin-orbit term have to be introduced at order $1/m_b^3$. Hence, no sources for additional hadronic uncertainties have to be taken into account. Similar arguments may be made for higher orders in the $1/m_b$ expansion.

We construct the phase diagram of the quark-antiquark and diquark condensates at finite temperature and density in the $2+1$ dimensional (3D) two flavor massless Gross-Neveu (GN) model with the 4-component quarks. In contrast to the case of the 2-component quarks, there appears the coexisting phase of the quark-antiquark and diquark condensates. This is the crucial difference between the 2-component and 4-component quark cases in the 3D GN model. The coexisting phase is also seen in the 4D Nambu Jona-Lasinio model. Then we see that the 3D GN model with the 4-component quarks bears closer resemblance to the 4D Nambu Jona-Lasinio model.

We show that the few-percent Okubo-Zweig-Iizuka-rule violating effects in the quark-flavor basis for the $\eta -{\eta }^{\prime }$ mixing can enhance the chiral scale associated with the ${\eta }_q$ meson a few times. This enhancement is sufficient for accommodating the dramatically different data of the $B\to {\eta }^{\prime }K$ and $B\to \eta K$ branching ratios. We comment on other proposals for resolving this problem, including flavor-singlet contributions, axial $U(1)$ anomaly, and nonperturbative charming penguins. Discrimination of the above proposals by means of the $B\to {\eta }^{(\prime )}\ell \nu$ and $B_s\to {\eta }^{(\prime )}\ell \ell$ data is suggested.

We obtain limits on generic vectorlike leptons at the TeV scale from electroweak precision tests. These limits are complementary to the ones obtained from lepton flavor violating processes. In general, the quality of the global electroweak fit is comparable to the one for the standard model. In the case of an extra neutrino singlet mixing with the muon or electron, the global fit allows for a relatively large Higgs mass ($M_H\lesssim 260\mathrm{GeV}$ at 90% C.L.), thus relaxing the tension between the direct CERN LEP limit and the standard model fit.

We present measurements of branching fractions for five $B$-meson decays to two-body charmless final states. The data, collected with the BABAR detector at the Stanford Linear Accelerator Center, represent $459\times {10}^6$ $B\overline{B}$ pairs. The results for branching fractions are, in units of ${10}^{-6}$ (upper limits at 90% C.L.), $\mathcal{B}(B^{+}\to \eta {\rho }^{+})=9.9\pm 1.2\pm 0.8$, $\mathcal{B}(B^0\to {\eta }^{\prime }\eta )=0.5\pm 0.4\pm 0.1(<1.2)$, $\mathcal{B}(B^0\to \eta {\pi }^0)=0.9\pm 0.4\pm 0.1(<1.5)$, $\mathcal{B}(B^0\to {\eta }^{\prime }{\pi }^0)=0.9\pm 0.4\pm 0.1(<1.5)$, and $\mathcal{B}(B^0\to \omega {\pi }^0)=0.07\pm 0.26\pm 0.02(<0.5)$. The first error quoted is statistical and the second systematic. For the $\eta {\rho }^{+}$ mode, we measure the charge asymmetry ${\mathcal{A}}_{ch}(B^{+}\to \eta {\rho }^{+})=0.13\pm 0.11\pm 0.02$.

In the present work, we investigate classical solutions of the Maxwell-Carroll-Field-Jackiw-Proca (MCFJP) electrodynamics for the cases of a purely timelike and spacelike Lorentz-violating (LV) background. Starting from the MCFJP Lagrangian and the associated wave equations written for the potential four-vector, the tensor form of the Green function is achieved. In the timelike case, the components of the stationary Green function are explicitly written. The classical solutions for the electric and magnetic field strengths are then evaluated, being observed that the electric sector is not modified by the LV background, keeping the Maxwell-Proca behavior. The magnetic field associated with a charge in uniform motion presents an oscillating behavior that also provides an oscillating MCFJ solution (in the limit of a vanishing Proca mass), but does not recover the Maxwell-Proca solution in the limit of vanishing background. In the spacelike case, the stationary Green function is written and also explicitly carried out in the regime of a small background. The electric and magnetic fields reveal to possess an exponentially decaying behavior, that recover the Maxwell-Proca solutions.

Using the brick wall method, the entropy of the charged dilaton-axion black hole is determined for both asymptotically flat and nonflat cases. The entropy turns out to be proportional to the horizon area of the black hole confirming the Bekenstein-Hawking area-entropy formula for black holes. The leading order logarithmic corrections to the entropy are also derived for such black holes.

We consider the longtime behavior of small amplitude solutions of the semilinear wave equation $\square \varphi ={\varphi }^p$ in odd $d\ge 5$ spatial dimensions. We show that for the quadratic nonlinearity ($p=2$) the tail has an anomalously small amplitude and fast decay. The extension of the results to more general nonlinearities involving first derivatives is also discussed.

We consider the basic physical properties of matter forming a thin accretion disc in the static and spherically symmetric space-time metric of the vacuum $f(R)$ modified gravity models. The Lagrangian of the generalized gravity theory is also obtained in a parametric form, and the conditions of the viability of the model are also discussed. The exact Schwarzschild-type solution of the gravitational field equations in the $f(R)$ gravity contains a linearly increasing term, as well as a logarithmic correction, as compared to the standard Schwarzschild solution of general relativity, and it depends on four arbitrary integration constants. The energy flux and the emission spectrum from the accretion disk around the $f(R)$ gravity black holes are obtained, and they are compared to the general relativistic case. Particular signatures can appear in the electromagnetic spectrum, thus leading to the possibility of directly testing modified gravity models by using astrophysical observations of the emission spectra from accretion disks.

We obtain and study the equations describing the parallel transport of orthonormal frames along geodesics in a spacetime admitting a nondegenerate, principal, conformal Killing-Yano tensor $\mathit{h}$. We demonstrate that the operator $\mathit{F}$, obtained by a projection of $\mathit{h}$ to a subspace orthogonal to the velocity, has in a generic case eigenspaces of dimension not greater than 2. Each of these eigenspaces is independently parallel propagated. This allows one to reduce the parallel transport equations to a set of first order, ordinary, differential equations for the angles of rotation in the 2D eigenspaces. General analysis is illustrated by studying the equations of the parallel transport in the Kerr-NUT-(A)dS metrics. Examples of three-, four-, and five-dimensional Kerr-NUT-(A)dS are considered, and it is shown that the obtained first order equations can be solved by a separation of variables.

A GHz maser beam with Gaussian-type distribution passing through a homogenous static magnetic field can be used to detect gravitational waves (GWs) with the same frequency. The presence of GWs will perturb the electromagnetic fields, giving rise to perturbed photon fluxes. After being reflected by a fractal membrane, the perturbed photons suffer little decay and can be measured by a microwave receiver. This idea has been explored to a certain extent as a method for very high-frequency gravitational waves. In this paper, we examine and develop this method more extensively, and confront the possible detection with the predicted signal of relic gravitational waves (RGWs). A maser beam with high linear polarization is used to reduce the background photon fluxes in the detecting direction as the main noise. As a key factor of applicability of this method, we give a preliminary estimation of the sensitivity of a sample detector limited by thermal noise using currently common technology. The minimal detectable amplitude of GWs is found to be $h_{\min }\sim {10}^{-30}$. Comparing with the known spectrum of the RGWs in the accelerating universe for $\beta =-1.9$, there is still roughly a gap of $4\sim 5$ orders. However, possible improvements on the detector can further narrow down the gap and make it a feasible method to detect high-frequency RGWs.

Black hole mimickers are possible alternatives to black holes; they would look observationally almost like black holes but would have no horizon. The properties in the near-horizon region where gravity is strong can be quite different for both types of objects, but at infinity it could be difficult to discern black holes from their mimickers. To disentangle this possible confusion, we examine the near-horizon properties, and their connection with far away asymptotic properties, of some candidates to black mimickers. We study spherically symmetric uncharged or charged but nonextremal objects, as well as spherically symmetric charged extremal objects. Within the uncharged or charged but nonextremal black hole mimickers, we study nonextremal $\epsilon$-wormholes on the threshold of the formation of an event horizon, of which a subclass are called black foils, and gravastars. Within the charged extremal black hole mimickers we study extremal $\epsilon$-wormholes on the threshold of the formation of an event horizon, quasi-black holes, and wormholes on the basis of quasi-black holes from Bonnor stars. We elucidate whether or not the objects belonging to these two classes remain regular in the near-horizon limit. The requirement of full regularity, i.e., finite curvature and absence of naked behavior, up to an arbitrary neighborhood of the gravitational radius of the object enables one to rule out potential mimickers in most of the cases. A list ranking the best black hole mimickers up to the worst, both nonextremal and extremal, is as follows: wormholes on the basis of extremal black holes or on the basis of quasi-black holes, quasi-black holes, wormholes on the basis of nonextremal black holes (black foils), and gravastars. Since in observational astrophysics it is difficult to find extremal configurations (the best mimickers in the ranking), whereas nonextremal configurations are really bad mimickers, the task of distinguishing black holes from their mimickers seems to be less difficult than one could think of it.

Recent analyses of the statistical distribution of the temperature anisotropies in the cosmic microwave background do not rule out the possibility that there is a large non-Gaussian contribution to the primordial power spectrum. This fact motivates the reanalysis of the curvaton scenario, paying special attention to the compatibility of large non-Gaussianity of the local type with the current detection limits on the isocurvature amplitude in the cosmic microwave background. We find that if the curvaton mechanism generates a primordial power spectrum with an important non-Gaussian component, any residual isocurvature imprint originated by the curvaton, would have an amplitude too big to be compatible with the current bounds. This implies that the isocurvature mode should be equal to zero in this scenario and we explore the consequences of this inference. In order to prevent the generation of a such a signal, the cold dark matter (CDM) must be created at a late stage, after the curvaton decays completely. This is used to constrain the nature of the CDM, arriving at a general relation between the temperature of the universe at CDM creation and the scale of inflation. It is possible to find an absolute maximum for the temperature at CDM creation, which is dependent on the particular inflationary potential. For a quadratic potential, we find $T_{\mathrm{cdm}}<1.7\times {10}^6\mathrm{GeV}$.