We investigate $K^{*}\Lambda (1116)$ photoproduction off the proton and neutron targets using the effective Lagrangian method in the tree-level Born approximation. In addition to the $K$, $K^{*}$, and $\kappa$ exchanges which are the main contributions to the reaction, we consider the contributions from the higher nucleon resonances $D_{13}(2080)$ and the $D_{15}(2200)$. We find that the $D_{13}(2080)$ plays a crucial role in explaining the enhancement of the near-threshold production rate, which results in a good agreement with the experimental data for the proton targets, while the contribution of the $D_{15}(2200)$ is rather small. A similar conclusion is drawn for $K^{*}$ photoproduction off the neutron targets. In addition to the energy and angular dependence of the cross sections, we present the predictions on the photon-beam asymmetry.

Interpreting the cosmological constant as a pressure, whose thermodynamically conjugate variable is a volume, modifies the first law of black hole thermodynamics. Properties of the resulting thermodynamic volume are investigated: the compressibility and the speed of sound of the black hole are derived in the case of nonpositive cosmological constant. The adiabatic compressibility vanishes for a nonrotating black hole and is maximal in the extremal case—comparable with, but still less than, that of a cold neutron star. A speed of sound $v_s$ is associated with the adiabatic compressibility, which is equal to $c$ for a nonrotating black hole and decreases as the angular momentum is increased. An extremal black hole has $v_s^2=0.9c^2$ when the cosmological constant vanishes, and more generally $v_s$ is bounded below by $c/\sqrt{2}$.

In this paper, we use the noncritical string/gauge duality to calculate the decay widths of large-spin mesons. Since it is believed that the string theory of QCD is not a ten-dimensional theory, we expect that the noncritical versions of ten-dimensional black hole backgrounds lead to better results than the critical ones. For this purpose we concentrate on the confining theories and consider two different six-dimensional black hole backgrounds. We choose the near-extremal ${\mathrm{AdS}}_6$ model and the near-extremal KM model to compute the decay widths of large-spin mesons. Then, we present our results from these two noncritical backgrounds and compare them together with those from the critical models and experimental data.

We propose an explicit model, where an axionic domain wall dynamically localizes a $U(1)$-component of a nonabelian gauge theory living in a $3+1$ dimensional bulk. The effective theory on the wall is $2+1d$ Maxwell-Chern-Simons (MCS) theory with a compact $U(1)$ gauge group. This setup allows us to understand all key properties of MCS theory in terms of the dynamics of the underlying $3+1$ dimensional gauge theory. Our findings can also shed some light on branes in supersymmetric gluodynamics.

We describe in detail a physical situation in which instantons are necessarily complex, not just Wick rotations of classical solutions to Euclidean spacetime. These complex instantons arise in the semiclassical evaluation of vacuum pair production rates, based on Feynman’s worldline path integral formulation. Even though the path integral is a sum over all real closed trajectories in spacetime, the semiclassical description of nonperturbative pair production is dominated by closed classical trajectories that are generically complex. These closed trajectories contain segments associated with nonperturbative instanton suppression factors as well as segments producing phase factors that incorporate quantum interference effects. For a class of time-dependent electric fields we implement this procedure and demonstrate excellent quantitative agreement with alternative methods.

We give an exact, analytic, and manifestly gauge invariant account of pair production in combined longitudinal and transverse electromagnetic fields, both depending arbitrarily on lightfront time. The instantaneous, nonperturbative probability of pair creation is given explicitly along with the spectra of the final particle yield. Our results are relevant to high-intensity QED experiments now being planned for future optical and x-ray free electron lasers.

We investigate the influence of the spacetime curvature on the interference of the radiation emitted by an ensemble of scalar sources in circular motion around a Schwarzschild black hole. We pay particular attention to the transition from the radiating to the nonradiating regime as the number of sources increases.

Thermal history of the Universe between inflation and big-bang nucleosynthesis has not yet been revealed observationally. It will be probed by the detection of primordial gravitational waves generated during inflation, which contain information on the reheating temperature as well as the equation of state of the Universe after inflation. Based on the Fisher information formalism, we examine how accurately the tensor-to-scalar ratio and reheating temperature after inflation can be simultaneously determined with space-based gravitational wave detectors such as the DECI-hertz Interferometer Gravitational-wave Observatory and the Big-Bang Observer. We show that the reheating temperature is best determined if it is around ${10}^7\mathrm{GeV}$ for tensor-to-scalar ratio of around 0.1, and explore the detectable parameter space. We also find that equation of state of the early Universe can be also determined accurately enough to distinguish different equation-of-state parameters if the inflationary gravitational waves are successfully detected. Thus, future gravitational wave detectors provide a unique and promising opportunity to reveal the thermal history of the Universe around ${10}^7\mathrm{GeV}$.

Measurements of cosmic microwave background (CMB) anisotropies constrain isocurvature fluctuations between photons and nonrelativistic particles to be subdominant to adiabatic fluctuations. Perturbations in the relative number densities of baryons and dark matter, however, are surprisingly poorly constrained. In fact, baryon-density perturbations of fairly large amplitude may exist if they are compensated by dark-matter perturbations, so that the total density remains unchanged. These compensated isocurvature perturbations (CIPs) leave no imprint on the CMB at observable scales, at linear order. B modes in the CMB polarization are generated at reionization through the modulation of the optical depth by CIPs, but this induced polarization is small. The strongest known constraint $\lesssim 10\%$ to the CIP amplitude comes from galaxy-cluster baryon fractions. Here, it is shown that modulation of the baryon density by CIPs at and before the decoupling of Thomson scattering at $z\sim 1100$ gives rise to CMB effects several orders of magnitude larger than those considered before. Polarization B modes are induced, as are correlations between temperature/polarization spherical-harmonic coefficients of different $lm$. It is shown that the CIP field at the surface of last scatter can be measured with these off-diagonal correlations. The sensitivity of ongoing and future experiments to these fluctuations is estimated. Data from the WMAP, ACT, SPT, and Spider experiments will be sensitive to fluctuations with amplitude $\sim 5–10\%$. The Planck satellite and Polarbear experiment will be sensitive to fluctuations with amplitude $\sim 3\%$. SPTPol, ACTPol, and future space-based polarization methods will probe amplitudes as low as $\sim 0.4\%–0.6\%$. In the cosmic-variance limit, the smallest CIPs that could be detected with the CMB are of amplitude $\sim 0.05\%$.

The measurement of a charge asymmetry in $t\overline{t}$ production at the LHC constitutes more than an independent confirmation of the forward-backward asymmetry found at the Tevatron. Indeed, both measurements together can be used to identify the source of the asymmetry. This is demonstrated for the case of new $Z^{\prime }$, $W^{\prime }$ vector bosons and color-sextet and triplet scalars, exchanged in $t$, $u$ channels, respectively, and a very heavy axigluon in the $s$ channel. In particular, current LHC measurements disfavor $Z^{\prime }$, $W^{\prime }$ models above the $2\sigma$ level.

We estimate the relative probabilities of ${\Psi }^{\prime }(2S)$ to $J/\Psi$ production at BNL-RHIC and ${\rm Y}(nS)$ production at the LHC and Fermilab in $p\mathrm{\text{−}}p$ collisions, using our recent theory of mixed heavy-quark hybrids, in which the ${\Psi }^{\prime }(2S)$ and ${\rm Y}(3S)$ mesons have approximately equal normal $q\overline{q}$ and hybrid $q\overline{q}g$ components.

A unitary coupled-channels model is presented for investigating the decays of heavy mesons and excited meson states into three light pseudoscalar mesons. The model accounts for the three-mesons final state interactions in the decay processes, as required by both the three-body and two-body unitarity conditions. In the absence of the $Z$-diagram mechanisms that are necessary consequences of the three-body unitarity, our decay amplitudes are reduced to a form similar to those used in the so-called isobar-model analysis. We apply our coupled-channels model to the three-pions decays of $a_1(1260)$, ${\pi }_2(1670)$, ${\pi }_2(2100)$, and $D^0$ mesons, and show that the $Z$-diagram mechanisms can contribute to the calculated Dalitz plot distributions by as much as 30% in magnitudes in the regions where $f_0(600)$, $\rho (770)$, and $f_2(1270)$ dominate the distributions. Also, by fitting to the same Dalitz plot distributions, we demonstrate that the decay amplitudes obtained with the unitary model and the isobar model can be rather different, particularly in the phase that plays a crucial role in extracting the Cabibbo-Kobayashi-Maskawa $CP$-violating phase from the data of $B$ meson decays. Our results indicate that the commonly used isobar-model analysis must be extended to account for the final state interactions required by the three-body unitarity to reanalyze the three-mesons decays of heavy mesons, thereby exploring hybrid or exotic mesons, and signatures of physics beyond the standard model.

We report updated branching fraction measurements of the color-suppressed decays ${\overline{B}}^0\to D^0{\pi }^0$, $D^{*0}{\pi }^0$, $D^0\eta$, $D^{*0}\eta$, $D^0\omega$, $D^{*0}\omega$, $D^0{\eta }^{\prime }$, and $D^{*0}{\eta }^{\prime }$. We measure the branching fractions ($\times {10}^{-4}$): $\mathcal{B}({\overline{B}}^0\to D^0{\pi }^0)=2.69\pm 0.09\pm 0.13$, $\mathcal{B}({\overline{B}}^0\to D^{*0}{\pi }^0)=3.05\pm 0.14\pm 0.28$, $\mathcal{B}({\overline{B}}^0\to D^0\eta )=2.53\pm 0.09\pm 0.11$, $\mathcal{B}({\overline{B}}^0\to D^{*0}\eta )=2.69\pm 0.14\pm 0.23$, $\mathcal{B}({\overline{B}}^0\to D^0\omega )=2.57\pm 0.11\pm 0.14$, $\mathcal{B}({\overline{B}}^0\to D^{*0}\omega )=4.55\pm 0.24\pm 0.39$, $\mathcal{B}({\overline{B}}^0\to D^0{\eta }^{\prime })=1.48\pm 0.13\pm 0.07$, and $\mathcal{B}({\overline{B}}^0\to D^{*0}{\eta }^{\prime })=1.49\pm 0.22\pm 0.15$. We also present the first measurement of the longitudinal polarization fraction of the decay channel $D^{*0}\omega$, $f_L=(66.5\pm 4.7\pm 1.5)\%$. In the above, the first uncertainty is statistical and the second is systematic. The results are based on a sample of $(454\pm 5)\times {10}^6$ $B\overline{B}$ pairs collected at the $\mathit{{\rm Y}}(4S)$ resonance, with the BABAR detector at the PEP-II storage rings at SLAC. The measurements are the most precise determinations of these quantities from a single experiment. They are compared to theoretical predictions obtained by factorization, Soft Collinear Effective Theory (SCET) and perturbative QCD (pQCD). We find that the presence of final state interactions is favored and the measurements are in better agreement with SCET than with pQCD.

Using the bottom-up approach in a holographic setting, we attempt to study both the transport and thermodynamic properties of a generic system in $3+1$-dimensional bulk spacetime. We show the exact $1/T$ and $T^2$ dependence of the longitudinal conductivity and Hall angle, as seen experimentally in most copper-oxide systems, which are believed to be close to quantum critical point. This particular temperature dependence of the conductivities are possible in two different cases: (1) background solutions with scale invariant and broken rotational symmetry and (2) solutions with pseudoscaling and unbroken rotational symmetry, but only at low density limit. Generically, the study of the transport properties in a scale-invariant background solution, using the probe brane approach, at high density and at low temperature limit suggests we consider only metrics with two exponents. More precisely, the spatial part of the metric components should not be same, i.e. $g_{xx}\ne g_{yy}$. In doing so, we have generalized the above-mentioned behavior of conductivity with a very special behavior of specific heat which at low temperature goes as: $C_V\sim T^3$. However, if we break the scaling symmetry of the background solution by including a nontrivial dilaton, axion, or both and keep the rotational symmetry, then also we can generate such a behavior of conductivity, but only in the low density regime. As far as we are aware, this particular temperature dependence of both the conductivity and Hall angle is being shown for the first time using holography.

We resolve a problem of finding the Poincaré symmetries from Hamiltonian gauge symmetries constructed through a canonical procedure of handling constrained systems. Through the use of Noether identities corresponding to the symmetries, we motivate a procedure of finding the map between the Hamiltonian and Poincaré gauge parameters. Using this map, we show that the Poincaré and Hamiltonian gauge symmetries are equivalent, modulo trivial gauge transformations.

LISA Pathfinder (LPF) is a mission aiming to test the critical technology for the forthcoming space-based gravitational-wave detectors. The main scientific objective of the LPF mission is to demonstrate test masses free falling with residual accelerations below $3\times {10}^{-14}\mathrm{m}{\mathrm{s}}^{-2}/\sqrt{\mathrm{Hz}}$ at 1 mHz. Reaching such an ambitious target will require a significant amount of system optimization and characterization, which will in turn require accurate and quantitative noise analysis procedures. In this paper, we discuss two main problems associated with the analysis of the data from LPF: i) excess noise detection and ii) noise parameter identification. The mission is focused on the low-frequency region ([0.1, 10] mHz) of the available signal spectrum. In such a region, the signal is dominated by the force noise acting on test masses. At the same time, the mission duration is limited to 90 days and typical data segments will be 24 hours in length. Considering those constraints, noise analysis is expected to deal with a limited amount of non-Gaussian data, since the spectrum statistics will be far from Gaussian and the lowest available frequency is limited by the data length. In this paper, we analyze the details of the expected statistics for spectral data and develop two suitable excess noise estimators. One is based on the statistical properties of the integrated spectrum, the other is based on the Kolmogorov-Smirnov test. The sensitivity of the estimators is discussed theoretically for independent data, then the algorithms are tested on LPF synthetic data. The test on realistic LPF data allows the effect of spectral data correlations on the efficiency of the different noise excess estimators to be highlighted. It also reveals the versatility of the Kolmogorov-Smirnov approach, which can be adapted to provide reasonable results on correlated data from a modified version of the standard equations for the inversion of the test statistic. Closely related to excess noise detection, the problem of noise parameter identification in non-Gaussian data is approached in two ways. One procedure is based on the maximum-likelihood estimator and another is based on the Kolmogorov-Smirnov goodness-of-fit estimator. Both approaches provide unbiased and accurate results for noise parameter estimation and demonstrate superior performance with respect to standard weighted least squares and Huber’s norm. We also discuss the advantages of the Kolmogorov-Smirnov formalism for the estimation of confidence intervals of parameter values in correlated data.

At high energies the gluon-gluon fusion is the dominant mechanism of $c\overline{c}$ production. This process was calculated in the next-to-leading-order collinear as well as in the $k_t$-factorization approaches in the past. We show that the present knowledge of gluon distributions does not allow one to make precise predictions for $c\overline{c}$ production at LHC, in particular at forward rapidities. In this paper we study production of $c\overline{c}$ pairs including several subleading mechanisms. This includes $gg\to Q\overline{Q}$, $\gamma g\to Q\overline{Q}$, $g\gamma \to Q\overline{Q}$, and $\gamma \gamma \to Q\overline{Q}$. In this context we use Martin-Roberts-Stirling-Thorne QED parton distributions which include the photon as a parton in the proton as well as elastic photon distributions calculated in the equivalent photon approximation. We present distributions in the $c$ quark ($\overline{c}$ antiquark) rapidity and transverse momenta and compare them to the dominant gluon-gluon fusion contribution. We discuss also inclusive single and central diffractive processes using diffractive parton distribution found from the analysis of HERA diffractive data. As in the previous case we present the distribution in $c$ ($\overline{c}$) rapidity and transverse momentum. Finally, we present results for an exclusive central diffractive mechanism discussed recently in the literature. We show corresponding differential distributions and compare them with corresponding distributions for single and central diffractive components.

We study the role of a very general type of flavor symmetry in controlling the strength of $R$-parity violation in supersymmetric models. We assume that only leptons are charged under a global symmetry whose breaking induces lepton number (and, hence, $R$-parity) violation. The charge assignments of leptons under this symmetry are such that the total number of independent lepton number violating couplings is reduced from 39 to 6. The most severe constraints on these flavor-correlated couplings arise from neutrino masses and mixing as well as from the nonobservation of $K_L\to \mu e$. We find that such a scenario predicts an almost vanishing smallest neutrino mass eigenvalue, allowing the upcoming generation of neutrinoless double beta decay experiments to shed light on the hierarchy.

We show that the recently considered McGreevy-Swingle model for Majorana fermions in the presence of a ’t Hooft-Polyakov magnetic monopole arises when the Jackiw-Rebbi model is constrained to be conjugation self dual.