We discuss the rotation of the linear polarization plane and the production of circular polarization generated by a cosmological pseudoscalar field. We compute analytically and numerically the propagation of the Stokes parameters from the last scattering surface for an oscillating and a monotonic decreasing pseudoscalar field. For the models studied in this paper, we show the comparison between the widely used approximation in which the linear polarization rotation angle is constant in time and the exact result.

The concept of “age” as a parameter for the description of the state of development of high energy showers in the atmosphere has been in use in cosmic ray studies for several decades. In this work we briefly discuss how this concept, originally introduced to describe the average behavior of electromagnetic cascades, can be fruitfully applied to describe individual showers generated by primary particles of different nature, including protons, nuclei and neutrinos. Showers with the same age share three different important properties: (i) their electron size has the same fractional rate of change with increasing depth, (ii) the bulk of the electrons and photons in the shower (excluding high energy particles) have energy spectra with shapes and relative normalization uniquely determined by the age parameter, and (iii) the electrons and photons in the shower have also the same angular and lateral distributions sufficiently far from the shower axis. In this work we discuss how the properties associated with the shower age can be understood with simple arguments, and how the shapes of the electron and photon spectra and the relative normalization that correspond to a certain age can be calculated analytically.

We study the effect of a nonuniversal $Z^{\prime }$ boson in the decay modes $B\to K\pi$. In the standard model these modes receive dominant contributions from $b\to s$ QCD penguins. Therefore, in this limit one expects $S_{{\pi }^0{K}^0}\approx \sin 2\beta$, $A_{{\pi }^0{K}^0}\approx 0$, and $A_{{\pi }^0{K}^{-}}\approx A_{{\pi }^{+}{K}^{-}}$. The corrections due to the presence of small nonpenguin contributions is found to yield $S_{{\pi }^0{K}^0}>\sin 2\beta$ and $\Delta A_{CP}(K\pi )\simeq 2.5\%$. However, the measured value of $S_{{\pi }^0{K}^0}$ is less than $\sin 2\beta$ and $\Delta A_{CP}(K\pi )\simeq 15\%$. We show the model with a nonuniversal $Z^{\prime }$ boson can successfully explain these anomalies.

Generalized form factors of hadrons are objects appearing in moments of the generalized parton distributions. Their leading-order DGLAP-ERBL QCD evolution is exceedingly simple and the solution is given in terms of matrix triangular structures of linear equations where the coefficients are the evolution ratios. We point out that this solution has a practical importance in analyses where the generalized form factors are basic objects, e.g., the lattice-gauge studies or models. It also displays general features of their evolution.

We study a new signature of lepton flavor violation (LFV) at the photon collider within supersymmetric theories. We consider the minimal supersymmetric standard model within a large $\tan \beta$ scenario with all superpartner masses in the $\mathcal{O}(\mathrm{TeV})$ while the heavy Higgs bosons masses lie below the TeV and develop sizable loop induced LFV couplings to the leptons. We consider a photon collider based on an $e^{+}{e}^{-}$ linear collider with $\sqrt{s}=800\mathrm{GeV}$ with the parameters of the TESLA proposal and show that, with the expected integrated $\gamma \gamma$ luminosity $L_{\gamma \gamma }=200–500{\mathrm{fb}}^{-1}$, the “$\mu \tau$ fusion” mechanism is the dominant channel for the process $\gamma \gamma \to \mu \tau b\overline{b}$ providing detailed analytical and numerical studies of the signal and backgrounds. We impose on the parameter space present direct and indirect constraints from $B$ physics and rare LFV $\tau$ decays and find that the LFV signal can be probed for masses of the heavy neutral Higgs bosons $A$, $H$ from 300 GeV up to the kinematical limit $\simeq 600\mathrm{GeV}$ for $30\le \tan \beta \le 60$.

We present a holographical soft wall model that is able to reproduce not only Regge spectra for hadrons with arbitrary integer spin, but also with spin $1/2$ and $3/2$, and with an arbitrary number of constituents. The model includes the anomalous dimension of operators that create hadrons, together with a dilaton, whose form is suggested by Einstein equations and the AdS metric used.

We investigate the minimal supergravity signals at the Large Hadron Collider in the context of supercritical string cosmology (SSC). In this theory, the presence of a time dependent dilaton provides us with a smoothly evolving dark energy and modifies the dark matter allowed region of the minimal supergravity model with standard cosmology. Such a dilaton dilutes the supersymmetric dark matter density (of neutralinos) by a factor $\mathcal{O}(10)$ and consequently the regions with too much dark matter in the standard scenario are allowed in the SSC. The final states expected at the Large Hadron Collider in this scenario, unlike the standard scenario, consist of $Z$ bosons, Higgs bosons, and/or high energy taus. We show how to characterize these final states and determine the model parameters. Using these parameters, we determine the dark matter content and the neutralino-proton cross section. All these techniques can also be applied to determine model parameters in SSC models with different supersymmetry breaking scenarios.

In the minimal supersymmetric model the R-parity violating top quark interactions, which are so far weakly constrained, can induce various flavor-changing neutral-current (FCNC) productions for the top quark at the large hadron collider (LHC). In this work we assume the presence of the B-violating couplings and examine their contributions to the FCNC productions proceeding through the parton processes $cg\to t$, $gg\to t\overline{c}$, $cg\to t\gamma$, $cg\to tZ$ and $cg\to th$. We find that all these processes can be greatly enhanced relative to the R-parity preserving predictions. In the parameter space allowed by current experiments, all the production channels except $cg\to th$ can reach the $3\sigma$ sensitivity, in contrast to the R-parity preserving case in which only $cg\to t$ can reach the $3\sigma$ sensitivity.

Taking a phenomenological approach, we study a color sextet scalar at the LHC. We focus on the QCD production of a color sextet pair ${\Phi }_6{\overline{\Phi }}_6$ through $gg$ fusion and $q\overline{q}$ annihilation. Its unique coupling to ${\overline{\psi }}^c\psi$ allows the color sextet scalar to decay into same-sign diquark states, such as ${\Phi }_6\to tt/t{t}^{*}$. We propose a new reconstruction in the multijet plus same-sign dilepton with missing transverse energy samples ($bb+{\ell }^{\pm }{\ell }^{\pm }+{\mathrm{E̸}}_T+Nj$, $N\ge 6$) to search for on-shell $tt\overline{t}\overline{t}$ final states from sextet scalar pair production. Thanks to the large QCD production, the search covers the sextet mass range up to 1 TeV for $100{\mathrm{fb}}^{-1}$ integrated luminosity.

We analyze the amplitude of radiative charged pion photoproduction within the framework of heavy baryon chiral perturbation theory and discuss the best experimental setup for the extraction of the charged pion polarizabilities from the differential cross section. We find that the contributions from two unknown low-energy constants in the $\pi N$ chiral Lagrangian at order $p^3$ are comparable with the contributions of the charged pion polarizabilities. As a result, it is necessary to take the effects of these low-energy constants into account. Furthermore, we discuss the applicability of the extrapolation method and conclude that this method is applicable only if the polarization vector of the incoming photon is perpendicular to the scattering plane in the center-of-mass frame of the final $\gamma \mathrm{\text{−}}\pi$ system.

We discuss the issue of duality violations in hadronic tau decay. After introducing a physically motivated ansatz for duality violations, we estimate their possible size by fitting this ansatz to the tau experimental data provided by the ALEPH Collaboration. Our conclusion is that these data do not exclude significant duality violations in tau decay. This may imply an additional systematic error in the value of ${\alpha }_s(m_{\tau })$, extracted from tau decay, as large as $\delta {\alpha }_s(m_{\tau })\sim 0.003–0.010$.

The variances and covariances associated to the nuclear matrix elements of neutrinoless double beta decay ($0\nu \beta \beta$) are estimated within the quasiparticle random phase approximation. It is shown that correlated nuclear matrix elements uncertainties play an important role in the comparison of $0\nu \beta \beta$ decay rates for different nuclei, and that they are degenerate with the uncertainty in the reconstructed Majorana neutrino mass.

We calculate the magnetic dipole moment of the $\Delta (1232)$ and ${\Omega }^{-}$ baryons with $2+1$ flavors of clover fermions on anisotropic lattices using a background magnetic field. This is the first dynamical calculation of these magnetic moments using a background field technique. The calculation for ${\Omega }^{-}$ is done at the physical strange quark mass, with the result in units of the physical nuclear magneton ${\mu }_{{\Omega }^{-}}=-1.93\pm 0.08\pm 0.12$ (where the first error is statistical and the second is systematic) compared to the experimental number: $-2.02\pm 0.05$. The $\Delta$ has been studied at three unphysical quark masses, corresponding to pion mass $m_{\pi }=366$, 438, and 548 MeV. The pion mass dependence is compared with the behavior obtained from chiral effective field theory.

The decaying speed of sound can lead to the emergence of the primordial density perturbation in any expanding phase, even if the expansion is decelerated. Recently, some proposals have been given to implement this mechanism, in which it was found that the primordial spectrum of scalar perturbation can be scale invariant. In this paper, we will give more insights for the details of this seeding mechanism.

We study the stability of supersymmetry breaking vacuum in the presence of cosmic strings arising in the messenger sector. For certain ranges of the couplings, the desired supersymmetry breaking vacua become unstable against decay into phenomenologically unacceptable vacua. This sets constraints on the range of allowed values of the coupling constants appearing in the models and more generally on the chosen dynamics of gauge symmetry breaking.

We improve and generalize a resummation method of post-Newtonian multipolar waveforms from circular (nonspinning) compact binaries introduced in Refs. [1,2]. One of the characteristic features of this resummation method is to replace the usual additive decomposition of the standard post-Newtonian approach by a multiplicative decomposition of the complex multipolar waveform $h_{\ell m}$ into several (physically motivated) factors: (i) the Newtonian waveform, (ii) a relativistic correction coming from an “effective source,” (iii) leading-order tail effects linked to propagation on a Schwarzschild background, (iv) a residual tail dephasing, and (v) residual relativistic amplitude corrections $f_{\ell m}$. We explore here a new route for resumming $f_{\ell m}$ based on replacing it by its $\ell$-th root: ${\rho }_{\ell m}=f_{\ell m}^{1/\ell }$. In the extreme-mass-ratio case, this resummation procedure results in a much better agreement between analytical and numerical waveforms than when using standard post-Newtonian approximants. We then show that our best approximants behave in a robust and continuous manner as we deform them by increasing the symmetric mass ratio $\nu \equiv m_1{m}_2/(m_1+m_2{)}^2$ from 0 (extreme-mass-ratio case) to $1/4$ (equal-mass case). The present paper also completes our knowledge of the first post-Newtonian corrections to multipole moments by computing ready-to-use explicit expressions for the first post-Newtonian contributions to the odd-parity (current) multipoles.

We simulate two dynamical, mass-degenerate light quarks on ${16}^3\times 32$ lattices with a spatial extent of 2.4 fm using the chirally improved Dirac operator. The simulation method, the implementation of the action, and signals of equilibration are discussed in detail. Based on the eigenvalues of the Dirac operator we discuss some qualitative features of our approach. Results for ground-state masses of pseudoscalar and vector mesons as well as for the nucleon and delta baryons are presented.

We study five-dimensional black holes obtained by compactifying M theory on Calabi-Yau threefolds. Recent progress in solving topological string theory on compact, one-parameter models allows us to test numerically various conjectures about these black holes. We give convincing evidence that a microscopic description based on Gopakumar-Vafa invariants accounts correctly for their macroscopic entropy, and we check that highly nontrivial cancellations—which seem necessary to resolve the so-called entropy enigma in the Ooguri-Strominger-Vafa conjecture—do in fact occur. We also study analytically small 5d black holes obtained by wrapping M2 branes in the fiber of K3 fibrations. By using heterotic/type II duality we obtain exact formulae for the microscopic degeneracies in various geometries, and we compute their asymptotic expansion for large charges.

According to Susskind, a string falling toward a black hole spreads exponentially over the stretched horizon due to repulsive interactions of the string bits. In this paper such a string is modeled as a self-avoiding walk and the string entropy is found. It is shown that the rate at which information/entropy contained in the string spreads is the maximum rate allowed by quantum theory. The maximum rate at which the black hole entropy can increase when a string falls into a black hole is also discussed.

In this series we construct an effective field theory (EFT) in curved spacetime to study gravitational radiation and backreaction effects. We begin in this paper with a derivation of the self-force on a compact object moving in the background spacetime of a supermassive black hole. The EFT approach utilizes the disparity between two length scales, which in this problem are the size of the compact object $r_m$ and the radius of curvature of the background spacetime $\mathcal{R}$ such that $\epsilon \equiv r_m/\mathcal{R}\ll 1$, to treat the orbital dynamics of the compact object, described as an effective point particle, separately from its tidal deformations. The equation of motion of an effective relativistic point particle coupled to the gravitational waves generated by its motion in a curved background spacetime can be derived without making a slow motion or weak field approximation, as was assumed in earlier EFT treatment of post-Newtonian binaries. Ultraviolet divergences are regularized using Hadamard’s partie finie to isolate the nonlocal finite part from the quasilocal divergent part. The latter is constructed from a momentum space representation for the graviton retarded propagator and is evaluated using dimensional regularization in which only logarithmic divergences are relevant for renormalizing the parameters of the theory. As a first important application of this framework we explicitly derive the first-order self-force given by Mino, Sasaki, Tanaka, Quinn, and Wald. Going beyond the point particle approximation, to account for the finite size of the object, we demonstrate that for extreme mass ratio inspirals the motion of a compact object is affected by tidally induced moments at $O({\epsilon }^4)$, in the form of an effacement principle. The relatively large radius-to-mass ratio of a white dwarf star allows for these effects to be enhanced until the white dwarf becomes tidally disrupted, a potentially $O({\epsilon }^2)$ process, or plunges into the supermassive black hole. This work provides a new foundation for further exploration of higher order self-force corrections, gravitational radiation, and spinning compact objects.