With the new measurements of $J/\psi$ and ${\psi }^{\prime }\to \gamma {\eta }_c(\gamma {\eta }_c^{\prime })$ from the CLEO and BES-III collaboration, we reinvestigate the intermediate meson loop (IML) contributions to these radiative decays in association with the quark model M1 transitions in an effective Lagrangian approach. It shows that the “unquenched” effects due to the intermediate hadron loops can be better quantified by the new data for $J/\psi \to \gamma {\eta }_c$. Although the IML contributions are relatively small in $J/\psi \to \gamma {\eta }_c$, they play a crucial role in ${\psi }^{\prime }\to \gamma {\eta }_c(\gamma {\eta }_c^{\prime })$. A prediction for the IML contributions to $\psi (3770)\to \gamma {\eta }_c(\gamma {\eta }_c^{\prime })$ is made. Such unquenched effects allow us to reach a coherent description of those three radiative transitions, and gain some insights into the underlying dynamics.

We make use of recent results in effective theory and higher-order perturbative calculations to improve the theoretical predictions of the QCD contribution to the top-quark pair production forward-backward asymmetry at the Tevatron. In particular, we supplement the fixed-order next-to-leading order calculation with higher-order corrections from soft-gluon resummation at next-to next-to-leading order accuracy performed in two different kinematic schemes, which allows us to make improved predictions for the asymmetry in the $p\overline{p}$ and $t\overline{t}$ rest frames as a function of the rapidity and invariant mass of the $t\overline{t}$ pair. Furthermore, we provide binned results which can be compared with the recent measurements of the forward-backward asymmetry in events with a large pair invariant mass or rapidity difference. Finally, we calculate at $\mathrm{NLO}+\mathrm{NNLL}$ order the top-quark charge asymmetry at the LHC as a function of a lower rapidity cutoff for the top and antitop quarks.

We show that the latest and very precise dispersive data analyses require a large and very unnatural fine-tuning of the $1/N_c$ expansion at $N_c=3$ if the $f_0(600)$ and $K(800)$ light scalar mesons are to be considered predominantly $\overline{q}q$ states, which is not needed for light vector mesons. For this, we use scattering observables whose $1/N_c$ corrections are suppressed further than one power of $1/N_c$ for $\overline{q}q$ or glueball states, thus enhancing contributions of other nature. This is achieved without using unitarized ChPT, but if it is used we can also show that it is not just that the coefficients of the $1/N_c$ expansion are unnatural, but that the expansion itself does not even follow the expected $1/N_c$ scaling of a glueball or a $\overline{q}q$ meson.

We introduce shower deconstruction, a method to look for new physics in a hadronic environment. The method aims to be a full information approach using small jets. It assigns to each event a number $\chi$ that is an estimate of the ratio of the probability for a signal process to produce that event to the probability for a background process to produce that event. The analytic functions we derive to calculate these probabilities mimic what full event generators like Pythia or Herwig do and can be depicted in a diagrammatic way. As an example, we apply this method to a boosted Higgs boson produced in association with a $Z$ boson and show that this method can be useful to discriminate this signal from the $Z+\mathrm{\text{jets}}$ background.

We examine a recently proposed explanation of the liquid scintillator neutrino detector and MiniBooNE anomalies, given in terms of a sterile neutrino $N$ of the mass $40MeV\lesssim m_N\lesssim 80MeV$ mixed with ${\nu }_{\mu }$ at the strength ${10}^{-3}\lesssim |U_{\mu N}{|}^2\lesssim {10}^{-2}$ and which dominantly decays into a light neutrino and photon: $N\to \nu \gamma$. We check compatibility of this scenario with the existing experimental data on radiative $\tau$-lepton and $K$-meson decays. We find that neither of these data are able to totally rule out the above indicated region of $m_N-|U_{\mu N}{|}^2$. However, we show that the current experimental data on $K\to \mu \nu \gamma$ decay exclude a significant part of this region. We propose experimental cuts on this decay allowing to improve its sensitivity to the region in question. We also show that measurements of $K\to \mu \nu ee$ decay have good prospects for testing the decaying sterile neutrino scenario.

Following K. Balasubramanian and K. Narayan [J. High Energy Phys. 08 (2010) 014], we discuss certain lightlike deformations of ${\mathrm{AdS}}_5\times X^5$ in type IIB string theory sourced by a lightlike dilaton $\Phi (x^{+})$ dual to the $\mathcal{N}=4$ super Yang-Mills theory with a lightlike varying gauge coupling. We argue that, in the case where the $x^{+}$ direction is noncompact, these solutions describe anisotropic $3+1$-dim Lifshitz-like systems with a potential in the $x^{+}$ direction generated by the lightlike dilaton. We then describe solutions of this sort with a linear dilaton. This enables a detailed calculation of two-point correlation functions of operators dual to bulk scalars and helps illustrate the spatial structure of these theories. Following this, we discuss a nongeometric string construction involving a compactification along the $x^{+}$ direction of this linear dilaton system. We also point out similar IIB axionic solutions. Similar bulk arguments for $x^{+}$-noncompact can be carried out for deformations of ${\mathrm{AdS}}_4\times X^7$ in M theory.

We study the deconfinement of hadronic matter into quark matter in a protoneutron star focusing on the effects of the finite size on the formation of just deconfined color superconducting quark droplets embedded in the hadronic environment. The hadronic phase is modeled by the nonlinear Walecka model at finite temperature including the baryon octet and neutrino trapping. For quark matter we use an $SU(3{)}_f$ Nambu-Jona-Lasinio model including color superconductivity. The finite size effects on the just deconfined droplets are considered in the frame of the multiple reflection expansion. In addition, we consider that just deconfined quark matter is transitorily out of equilibrium respect to weak interaction, and we impose color neutrality and flavor conservation during the transition. We calculate self-consistently the surface tension and curvature energy density of the quark hadron interphase and find that it is larger than the values typically assumed in the literature. The transition density is calculated for drops of different sizes, and at different temperatures and neutrino trapping conditions. Then, we show that energy density fluctuations are much more relevant for deconfinement than temperature and neutrino density fluctuations. We calculate the critical size spectrum of energy density fluctuations that allows deconfinement as well as the nucleation rate of each critical bubble. We find that drops with any radii smaller than 800 fm can be formed at a huge rate when matter achieves the bulk transition limit of 5–6 times the nuclear saturation density.

We investigate the propagation modes of gauge fields in an infinite Randall-Sundrum scenario. In this model a sine-Gordon soliton represents our thick four-dimensional braneworld while an exponentially coupled scalar acts for the dilaton field. For the gauge-field motion we find a differential equation which can be transformed into a confluent Heun equation. By means of another change of variables we obtain a related Schrödinger equation with a family of symmetric rational $(\gamma -\omega z^2)/(1-z^2{)}^2$ potential functions. We discuss both results and present the infinite spectrum of analytical solutions for the gauge field. Finally, we assess the existence and the relative weights of Kaluza-Klein modes in the present setup.

We study some features of static and spherically symmetric solutions (SSS) with a horizon in $f(R)$ theories of gravitation by means of a near-horizon analysis. A necessary condition for an $f(R)$ theory to have this type of solution is obtained. General features of the effective potential are deduced, and it is shown that there exists a limit on the curvature at the horizon, in both cases for any $f(R)$. Finally, we calculate the expression for the energy of the collision of two massive particles in the center of mass frame.

Basic aspects of the background of gravitational waves and its mathematical characterization are reviewed. The spectral energy density parameter $\Omega (f)$, commonly used as a quantifier of the background, is derived for an ensemble of many identical sources emitting at different times and locations. For such an ensemble, $\Omega (f)$ is generalized to account for the duration of the signals and of the observation, so that one can distinguish the resolvable and unresolvable parts of the background. The unresolvable part, often called confusion noise or stochastic background, is made by signals that cannot be either individually identified or subtracted out of the data. To account for the resolvability of the background, the overlap function is introduced. This function is a generalization of the duty cycle, which has been commonly used in the literature, in some cases leading to incorrect results. The spectra produced by binary systems (stellar binaries and massive black hole binaries) are presented over the frequencies of all existing and planned detectors. A semi-analytical formula for $\Omega (f)$ is derived in the case of stellar binaries (containing white dwarfs, neutron stars or stellar-mass black holes). Besides a realistic expectation of the level of background, upper and lower limits are given, to account for the uncertainties in some astrophysical parameters such as binary coalescence rates. One interesting result concerns all current and planned ground-based detectors (including the Einstein Telescope). In their frequency range, the background of binaries is resolvable and only sporadically present. In other words, there is no stochastic background of binaries for ground-based detectors.

This is the second in a series of papers aimed at developing a practical time-domain method for self-force calculations in Kerr spacetime. The key elements of the method are (i) removal of a singular part of the perturbation field with a suitable analytic “puncture” based on the Detweiler-Whiting decomposition, (ii) decomposition of the perturbation equations in azimuthal ($m$-)modes, taking advantage of the axial symmetry of the Kerr background, (iii) numerical evolution of the individual $m$-modes in $2+1$ dimensions with a finite-difference scheme, and (iv) reconstruction of the physical self-force from the mode sum. Here we report an implementation of the method to compute the scalar-field self-force along circular equatorial geodesic orbits around a Kerr black hole. This constitutes a first time-domain computation of the self-force in Kerr geometry. Our time-domain code reproduces the results of a recent frequency-domain calculation by Warburton and Barack, but has the added advantage of being readily adaptable to include the backreaction from the self-force in a self-consistent manner. In a forthcoming paper—the third in the series—we apply our method to the gravitational self-force (in the Lorenz gauge).

The cause of the accelerated expansion of the Universe poses one of the most fundamental questions in physics today. In the absence of a compelling theory to explain the observations, a first task is to develop a robust phenomenological approach: If the acceleration is driven by some form of dark energy, then the phenomenology is determined by the form of the dark energy equation of state $w(z)$ as a function of redshift. A major aim of ongoing and upcoming cosmological surveys is to measure $w$ and its evolution at high accuracy. Since $w(z)$ is not directly accessible to measurement, powerful reconstruction methods are needed to extract it reliably from observations. We have recently introduced a new reconstruction method for $w(z)$ based on Gaussian process modeling. This method can capture nontrivial $w(z)$ dependences and, most importantly, it yields controlled and unbiased error estimates. In this paper we extend the method to include a diverse set of measurements: baryon acoustic oscillations, cosmic microwave background measurements, and supernova data. We analyze currently available data sets and present the resulting constraints on $w(z)$, finding that current observations are in very good agreement with a cosmological constant. In addition, we explore how well our method captures nontrivial behavior of $w(z)$ by analyzing simulated data assuming high-quality observations from future surveys. We find that the baryon acoustic oscillation measurements by themselves already lead to remarkably good reconstruction results and that the combination of different high-quality probes allows us to reconstruct $w(z)$ very reliably with small error bounds.

The CoGeNT Collaboration has recently presented the results of their first 15 months of data, including the measurement of the spectrum of nuclear recoil candidate events, and the time variation of those events. These results appear consistent with the signal anticipated from a relatively light dark matter particle scattering elastically with nuclei. In this paper, we independently analyze the data set collected by CoGeNT and explore the implications of these results for dark matter. We find that the observed spectrum and rate is consistent with originating from dark matter particles with a mass in the range of 4.5–12 GeV and an elastic scattering cross section with nucleons of approximately $\sim {10}^{-40}{\mathrm{cm}}^2$. We confirm the conclusion of the CoGeNT Collaboration that the data also includes a somewhat statistically significant ($2.7\sigma$) indication of annual modulation, with a phase, period, and amplitude consistent with that predicted for dark matter. CoGeNT’s phase is also consistent with the annual modulation reported by the DAMA/LIBRA Collaboration. We also discuss the null results reported by CDMS and XENON100, and comment on the prospects for other experiments to detect a dark matter particle with the properties implied by CoGeNT.

The IceCube Neutrino Observatory is a $1{\mathrm{km}}^3$ detector currently taking data at the South Pole. One of the main strategies used to look for astrophysical neutrinos with IceCube is the search for a diffuse flux of high-energy neutrinos from unresolved sources. A hard energy spectrum of neutrinos from isotropically distributed astrophysical sources could manifest itself as a detectable signal that may be differentiated from the atmospheric neutrino background by spectral measurement. This analysis uses data from the IceCube detector collected in its half completed configuration which operated between April 2008 and May 2009 to search for a diffuse flux of astrophysical muon neutrinos. A total of 12 877 upward-going candidate neutrino events have been selected for this analysis. No evidence for a diffuse flux of astrophysical muon neutrinos was found in the data set leading to a 90% C.L. upper limit on the normalization of an $E^{-2}$ astrophysical ${\nu }_{\mu }$ flux of $8.9\times {10}^{-9}\mathrm{GeV}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}{\mathrm{sr}}^{-1}$. The analysis is sensitive in the energy range between 35 TeV and 7 PeV. The 12 877 candidate neutrino events are consistent with atmospheric muon neutrinos measured from 332 GeV to 84 TeV and no evidence for a prompt component to the atmospheric neutrino spectrum is found.

Motivated by recent attempts to reconcile hints of direct dark matter detection by the CoGeNT and DAMA experiments, we construct simple particle physics models that can accommodate the constraints. We point out challenges for building reasonable models and identify the most promising scenarios for getting isospin violation and inelasticity, as indicated by some phenomenological studies. If inelastic scattering is demanded, we need two new light gauge bosons, one of which kinetically mixes with the standard model hypercharge and has mass $<2\mathrm{GeV}$, and another which couples to baryon number and has mass $6.8\pm \genfrac{}{}{0ex}{}{0.1}{0.2}\mathrm{GeV}$. Their interference gives the desired amount of isospin violation. The dark matter is nearly Dirac, but with small Majorana masses induced by spontaneous symmetry breaking, so that the gauge boson couplings become exactly off-diagonal in the mass basis, and the small mass splitting needed for inelasticity is simultaneously produced. If only elastic scattering is demanded, then an alternative model, with interference between the kinetically mixed gauge boson and a hidden sector scalar Higgs, is adequate to give the required isospin violation. In both cases, the light kinetically mixed gauge boson is in the range of interest for currently running fixed target experiments.

We investigate possible renormalization effects on the low-energy mass spectrum of the minimal supersymmetric standard model (MSSM), using a calculable model of strongly coupled hidden sector. We model the hidden sector by $\mathcal{N}=2$ supersymmetric quantum chromodynamics with gauge group $SU(2)\times U(1)$ and $N_f=2$ matter hypermultiplets, perturbed by a Fayet-Iliopoulos term which breaks the supersymmetry down to $\mathcal{N}=0$ on a metastable vacuum. In the hidden sector the Kähler potential is renormalized. Upon identifying a hidden sector modulus with the renormalization scale, and extrapolating to the strongly coupled regime using the Seiberg-Witten solution, the contribution from the hidden sector to the MSSM renormalization group flows is computed. For concreteness, we consider a model in which the renormalization effects are communicated to the MSSM sector via gauge mediation. In contrast to the perturbative toy examples of hidden sector renormalization studied in the literature, we find that our strongly coupled model exhibits rather intricate effects on the MSSM soft scalar mass spectrum, depending on how the hidden sector fields are coupled to the messenger fields. This model provides a concrete example in which the low-energy spectrum of MSSM particles that are expected to be accessible in collider experiments is obtained using strongly coupled hidden sector dynamics.

Sneutrino-antisneutrino oscillation can be a very useful probe to look for signatures of lepton number violation ($\Delta L=2$) at the Tevatron. Here, we discuss a scenario where the total decay width of the sneutrino is very small, producing interesting signals at the Tevatron for a mass splitting $\Delta m$ as small as ${10}^{-14}\mathrm{GeV}$ between the sneutrino mass eigenstates.

The anomaly of the top quark forward-backward asymmetry $A_{\mathrm{FB}}^t$ observed at the Tevatron can be explained by the $t$-channel exchange of a neutral gauge boson ($Z^{\prime }$) which has sizable flavor-changing coupling for top and up quarks. This gauge boson can also induce the top quark flavor-changing neutral-current (FCNC) decays and the like-sign top pair production at the LHC. In this work, we focus on two models which predict such a $Z^{\prime }$, namely, the left-right model and the $\mathrm{U}(1{)}_X$ model, to investigate the correlated effects on $A_{\mathrm{FB}}^t$, the FCNC decays $t\to uV$ ($V=g$, $Z$, $\gamma$) and the like-sign top pair production at the LHC. We also pay special attention to the most recently measured $A_{\mathrm{FB}}^t$ in the large top pair invariant mass region. We find that under the current experimental constraints both models can alleviate the deviation of $A_{\mathrm{FB}}^t$ and, meanwhile, enhance the like-sign top pair production to the detectable level of the LHC. We also find that the two models give different predictions for the observables and their correlations, and thus they may even be distinguished by jointly studying these top quark observables.

Based on Friedberg and Lee’s geometric picture by which the tribimaximal Pontecorvo-Maki-Nakawaga-Sakata leptonic mixing matrix is constructed, namely, corresponding mixing angles correspond to the geometric angles among the sides of a cube. We suggest that the three realistic mixing angles, which slightly deviate from the values determined for the cube, are due to a viable deformation from the perfectly cubic shape. Taking the best-fitted results of ${\theta }_{12}$ and ${\theta }_{23}$ as inputs, we determine the central value of ${sin}^{2}2{\theta }_{13}$ should be 0.0238, with a relatively large error tolerance; this value lies in the range of measurement precision of the Daya Bay experiment and is consistent with recent results from the T2K Collaboration.

We show that combining a direct measurement of the Higgs total width from the $H\to ZZ\to 4\ell$ lineshape with Higgs signal rate measurements allows Higgs couplings to be extracted in a model-independent way from CERN LHC data. Using existing experimental studies with $30{\mathrm{fb}}^{-1}$ at one detector of the 14 TeV LHC, we show that the couplings squared of a 190 GeV Higgs to $WW$, $ZZ$, and $gg$ can be extracted with statistical precisions of about 10%, and a 95% confidence level upper limit on an unobserved component of the Higgs decay width of about 22% of the standard model Higgs width can be set. The method can also be applied for heavier Higgs masses.