When taking the holographic principle into account, the vacuum energy will acquire dynamical property that its equation of state is evolving. The current available observational data imply that the holographic vacuum energy behaves as quintom-type dark energy. We adopt the viewpoint of that the scalar-field models of dark energy are effective theories of an underlying theory of dark energy. If we regard the scalar-field model as an effective description of such a holographic vacuum theory, we should be capable of using the scalar-field model to mimic the evolving behavior of the dynamical vacuum energy and reconstructing this scalar-field model according to the fits of the observational dataset. We find the generalized ghost condensate model is a good choice for depicting the holographic vacuum energy since it can easily realize the quintom behavior. We thus reconstruct the function $h(\varphi )$ of the generalized ghost condensate model using the best-fit results of the observational data.

We consider the possibility that the ultra-high-energy cosmic ray flux has a small component of exotic particles which create showers much deeper in the atmosphere than ordinary hadronic primaries. It is shown that applying the conventional AGASA/HiRes/Auger data analysis procedures to such exotic events results in large systematic biases in the energy spectrum measurement which may distort the shape of the measured spectrum near the expected Greisen-Zatsepin-Kuzmin (GZK) cutoff energy. Sub-GZK exotic showers may be misreconstructed with much higher energies and mimic super-GZK events. Alternatively, super-GZK exotic showers may elude detection by conventional fluorescence analysis techniques.

We calculate one-loop (purely) weak (W) corrections of $\mathcal{O}({\alpha }_{\mathrm{S}}^2{\alpha }_{\mathrm{W}})$ to the partonic cross section of two jets at Tevatron and prove that they can be larger than the tree-level $\mathcal{O}({\alpha }_{\mathrm{S}}{\alpha }_{\mathrm{EW}})$ and $\mathcal{O}({\alpha }_{\mathrm{EW}}^2)$ electroweak (EW) ones. At high transverse energy of the jets, all such corrections may lead to detectable effects of, e.g., $-10\%$ or so, with respect to the leading-order (LO) QCD term of $\mathcal{O}({\alpha }_{\mathrm{S}}^2)$, for the highest value so far probed by Run 2, depending on the factorization/renormalization scale. Besides, they increase significantly with jet transverse energy. Hence, our results show that EW corrections may be needed to fit the standard model (SM) to present and future Tevatron jet data.

Deviations from standard model expectations in the Higgs sector can be parametrized by an effective Lagrangian. The corresponding anomalous couplings have been implemented in a Monte Carlo program for Higgs production in vector boson fusion, at NLO QCD accuracy. It allows to study anomalous coupling effects for production and decay of the Higgs boson. We analyze deviations allowed by LEP data and study a new azimuthal angle variable which directly measures the interference between $CP$-even, $CP$-odd and standard model couplings.

A Ginsparg-Wilson based calibration of the topological charge is used to calculate the renormalization constants which appear in the field-theoretical determination of the topological susceptibility on the lattice. A systematic comparison is made with calculations based on cooling. The two methods agree within present statistical errors (3%–4%). We also discuss the independence of the multiplicative renormalization constant $Z$ from the background topological charge used to determine it.

This paper is devoted to the study of the process $e^{+}{e}^{-}\to J/\psi X(3940)$ in the framework of light-cone formalism. In our calculation two hypotheses about the structure of $X(3940)$ meson are considered: $X(3940)$ is $3{}^{1}S_0$ state and $X(3940)$ is one of $2{}^{3}P$ states. The former hypothesis leads to a good agreements with the cross section measured at the experiment. As to the latter one, it is proposed a mechanism that allows one to understand the suppression of $2P$ mesons production in hard processes.

In the limit of heavy quark masses going to infinity, a symmetry is known to emerge in QCD relating properties of hadrons with two heavy quarks to analogous states with one heavy antiquark. A key question is whether the charm mass is heavy enough so that this symmetry is manifest in at least an approximate manner. The issue is crucial in attempting to understand the recent reports by the SELEX Collaboration of doubly charmed baryons. We argue on very general grounds that the charm quark mass is substantially too light for the symmetry to emerge automatically via color coulombic interactions. However, the symmetry could emerge approximately depending on the dynamical details of the nonperturbative physics. To treat the problem systematically, a new expansion that simultaneously incorporates NRQCD and HQET is needed.

An attractive explanation for nonzero neutrino masses and small matter antimatter asymmetry of the present Universe lies in “leptogenesis”. At present the size of the lepton asymmetry is precisely known, while the sign is not known yet. In this work we determine the sign of this asymmetry in the framework of two right-handed neutrino models by relating the leptogenesis phase(s) with the low energy $CP$ violating phases appearing in the leptonic mixing matrix. It is shown that the knowledge of low energy lepton number violating rephasing invariants can indeed determine the sign of the present matter antimatter asymmetry of the Universe and hence indirectly probing the light physical neutrinos to be Majorana type.

A precise evaluation of the secondary particle production and propagation in the atmosphere is very important for the atmospheric neutrino oscillation studies. The issue is addressed with the extension of a previously developed full 3-dimensional Monte-Carlo simulation of particle generation and transport in the atmosphere, to compute the flux of secondary protons, muons, and neutrinos. Recent balloon borne experiments have performed a set of accurate flux measurements for different particle species at different altitudes in the atmosphere, which can be used to test the calculations for the atmospheric neutrino production, and constrain the underlying hadronic models. The simulation results are reported and compared with the latest flux measurements. It is shown that the level of precision reached by these experiments could be used to constrain the nuclear models used in the simulation. The implication of these results for the atmospheric neutrino flux calculation are discussed.

We present an $N=1$ supersymmetric non-Abelian compensator formulation for a vector multiplet in three dimensions. Our total field content is the off-shell vector multiplet $(A_{\mu }{}^I,{\lambda }^I)$ with the off-shell scalar multiplet $({\phi }^I,{\chi }^I;F^I)$ both in the adjoint representation of an arbitrary non-Abelian gauge group. This system is reduced to a supersymmetric $\sigma$ model on a group manifold, in the zero-coupling limit. Based on this result, we formulate a ‘self-dual’ non-Abelian vector multiplet in three dimensions. By an appropriate identification of parameters, the mass of the self-dual vector multiplet is quantized. Additionally, we also show that the self-dual non-Abelian vector multiplet can be coupled to the supersymmetric Dirac-Born-Infeld action. These results are further reformulated in superspace to get a clear overall picture.

We construct a supersymmetric rotating black hole with asymptotically flat four-dimensional spacetime times a circle, by superposing an infinite number of BMPV black hole solutions at the same distance in one direction. The near-horizon structure is the same as that of the five-dimensional BMPV black hole. The rotation of this black hole can exceed the Kerr bound in general relativity ($q\equiv a/G_{4}M=1$), if the size is small.

By introducing the generalized uncertainty principle, we calculate the entropy of the bulk scalar field on the Randall-Sundrum brane background without any cutoff. We obtain the entropy of the massive scalar field proportional to the horizon area. Here, we observe that the mass contribution to the entropy exists in contrast to all previous results of the usual black hole cases with the generalized uncertainty principle.

We propose an economical model of nonthermal leptogenesis following inflation during instant preheating. The model involves only the inflaton field, the standard model Higgs, and the heavy “right-handed” neutrino.

The radiation background produced by the 21 cm spin-flip transition of neutral hydrogen at high redshifts can be a pristine probe of fundamental physics and cosmology. At $z\sim 30–300$, the intergalactic medium (IGM) is visible in 21 cm absorption against the cosmic microwave background (CMB), with a strength that depends on the thermal (and ionization) history of the IGM. Here we examine the constraints this background can place on dark matter decay and annihilation, which could heat and ionize the IGM through the production of high-energy particles. Using a simple model for dark matter decay, we show that, if the decay energy is immediately injected into the IGM, the 21 cm background can detect $\mathrm{\text{energy injection rates}}\gtrsim {10}^{-24}\mathrm{eV}{\mathrm{cm}}^{-3}{\sec }^{-1}$. If all the dark matter is subject to decay, this allows us to constrain $\mathrm{\text{dark matter lifetimes}}\lesssim {10}^{27}\sec$. Such energy injection rates are much smaller than those typically probed by the CMB power spectra. The expected brightness temperature fluctuations at $z\sim 50$ are a fraction of a mK and can vary from the standard calculation by up to an order of magnitude, although the difference can be significantly smaller if some of the decay products free stream to lower redshifts. For self-annihilating dark matter, the fluctuation amplitude can differ by a $\mathrm{\text{factor}}\lesssim 2$ from the standard calculation at $z\sim 50$. Note also that, in contrast to the CMB, the 21 cm probe is sensitive to both the ionization fraction and the IGM temperature, in principle allowing better constraints on the decay process and heating history. We also show that strong IGM heating and ionization can lead to an enhanced ${\mathrm{H}}_2$ abundance, which may affect the earliest generations of stars and galaxies.

We derive the semiclassical evolution of massless minimally coupled scalar matter in the de Sitter space-time from the Born-Oppenheimer reduction of the Wheeler-DeWitt equation. We show that the dynamics of trans-Planckian modes can be cast in the form of an effective modified dispersion relation and that high energy corrections in the power spectrum of the cosmic microwave background radiation produced during inflation remain very small if the initial state is the Bunch-Davies vacuum.

We propose an exact renormalization group equation for lattice gauge theories, which has no dependence on the lattice spacing. We instead relate the lattice spacing properties directly to the continuum convergence of the support of each local plaquette. Equivalently, this is formulated as a convergence prescription for a characteristic polynomial in the gauge coupling that allows the exact meromorphic continuation of a nonperturbative system arbitrarily close to the continuum limit.

For compact U(1) lattice gauge theory we have performed a finite size scaling analysis on $N_{\tau }{N}_s^3$ lattices for $N_{\tau }$ fixed by extrapolating spatial volumes of size $N_s\le 18$ to $N_s\to \infty$. Within the numerical accuracy of the thus-obtained fits, we find for $N_{\tau }=4$, 5 and 6 second order critical exponents, which exhibit no obvious $N_{\tau }$ dependence. The exponents are consistent with 3d Gaussian values, but not with either first order transitions or the universality class of the 3d XY model. As the 3d Gaussian fixed point is known to be unstable, the scenario of a yet unidentified nontrivial fixed point close to the 3d Gaussian emerges as one of the possible explanations.

Time correlation functions of a hybrid exotic meson operator, with $J^{\mathrm{PC}}=1^{-+}$, generated in quenched lattice QCD are subjected to a (Bayesian) maximum entropy analysis. Five distinct spectral levels are uncovered. Their extrapolation into the physical pion mass region suggests a possible relationship to experimentally known states ${\pi }_1(1400)$ and ${\pi }_1(1600)$, and also to a state in the 2 GeV region carrying the same quantum numbers.

Using the high temperature approximation we study, within the linear response theory, the wake in the quark-gluon plasma by a fast parton owing to dynamical screening in the spacelike region. When the parton moves with a speed less than the average speed of the plasmon, we find that the wake structure corresponds to a screening charge cloud traveling with the parton with one sign flip in the induced charge density resulting in a Lennard-Jones type potential in the outward flow with a short range repulsive and a long range attractive part. On the other hand if the parton moves with a speed higher than that of plasmon, the wake structure in the induced charge density is found to have alternate sign flips and the wake potential in the outward flow oscillates analogous to Cerenkov-like wave generation with a Mach cone structure trailing the moving parton. The potential normal to the motion of the parton indicates a transverse flow in the system. We also calculate the potential due to a color dipole and discuss consequences of possible new bound states and $J/\psi$ suppression in the quark-gluon plasma.

The baryon axial vector current is computed at one-loop order in heavy baryon chiral perturbation theory in the large-$N_c$ limit, where $N_c$ is the number of colors. Loop graphs with octet and decuplet intermediate states cancel to various orders in $N_c$ as a consequence of the large-$N_c$ spin-flavor symmetry of QCD baryons. These cancellations are explicitly shown for the general case of $N_f$ flavors of light quarks. In particular, a new generic cancellation is identified in the renormalization of the baryon axial vector current at one-loop order. A comparison with conventional heavy baryon chiral perturbation theory is performed at the physical values $N_c=3$, $N_f=3$.