We investigate the sensitivity to the effective operators describing interactions between dark matter particles and photons at future high energy $e^{+}{e}^{-}$ colliders via the $\gamma +\mathrm{E̸}$ channel. Such operators could be useful to interpret the potential gamma-ray line signature observed by the Fermi-LAT. We find that these operators can be further tested at $e^{+}{e}^{-}$ colliders by using either unpolarized or polarized beams. We also derive a general unitarity condition for $2\to n$ processes and apply it to the dark matter production process $e^{+}{e}^{-}\to \chi \chi \gamma$.

The CERN Resonant Weakly Interacting sub-eV Particle Search probes the existence of weakly interacting sub-eV particles like axions or hidden sector photons. It is based on the principle of an optical light shining through the wall experiment, adapted to microwaves. Critical aspects of the experiment are electromagnetic shielding, design and operation of low loss cavity resonators, and the detection of weak sinusoidal microwave signals. Lower bounds are set on the coupling constant $g=4.5\times {10}^{-8}{\mathrm{GeV}}^{-1}$ for axionlike particles with a mass of $m_a=7.2\mu \mathrm{eV}$. For hidden sector photons, lower bounds are set for the coupling constant $\chi =4.1\times {10}^{-9}$ at a mass of $m_{{\gamma }^{\prime }}=10.8\mu \mathrm{eV}$. For the latter we are probing a previously unexplored region in the parameter space.

There are generally two types of Wick contractions in lattice QCD calculations of a correlation function: connected and disconnected ones. The disconnected contribution is difficult to calculate and noisy, thus it is often neglected. In the context of studying tetraquarks, hadronic molecules, and meson-meson scattering, we show that whenever there are both connected and singly disconnected contractions, the singly disconnected part gives the leading order contribution, and thus should never be neglected. As an explicit example, we show that information about the scalar mesons $\sigma$, $f_0(980)$, $a_0(980)$, and $\kappa$ will be lost when neglecting the disconnected contributions.

The leading-order hadronic contribution to the muon anomalous magnetic moment is given by a weighted integral over the subtracted hadronic vacuum polarization. This integral is dominated by Euclidean momenta of order the muon mass, i.e., momenta not accessible on current lattice volumes with periodic boundary conditions. Twisted boundary conditions can in principle help in accessing momenta of any size even in a finite volume, but their use leads to a modification of the Ward-Takahashi identity that normally guarantees transversality of the vacuum polarization. As a result, the vacuum polarization contains a nontransverse, quadratically divergent term, which arises as an artifact of using twisted boundary conditions in a finite volume. In this paper, we show how to determine and remove this term from the vacuum polarization.

We consider hard diffractive events in proton-proton collisions at the LHC, in which both protons escape the collision intact. In such double Pomeron exchange processes, we propose to measure dijets and photon-jet final states, and we show that it has the potential to pin down the Pomeron quark and gluon contents, a crucial ingredient in the standard QCD description of hard diffraction. By comparing with predictions of the soft color interaction approach, we also show that more generally, the measurement of the photon-jet to dijet cross section ratio can put a stringent test on the QCD dynamics at play in diffractive processes in hadronic collisions.

We consider the production of excited leptons ($\overline{l^{*}}l$ as well as $\overline{l^{*}}{l}^{*}$) at the LHC, followed by their two-body decay into standard model particles. We perform the next-to-leading-order QCD corrections to these processes. In spite of the nonrenormalizable nature of the interaction, such calculations are possible and meaningful. Not only are these corrections substantial and significant, the scale dependence of the next-to-leading-order cross section is greatly reduced as compared to that for the leading-order cross sections.

Dark matter collisions with heavy nuclei (Xe, Ge, Si, Na) may produce recoils observable at direct-search experiments. Given that some of these experiments are yielding conflicting information, however, it is worth asking if physics other than dark matter may produce similar nuclear recoils. We examine under what conditions an atmospherically produced neutral particle with a relatively large magnetic dipole moment could fake a dark matter signal. We argue that a very definite flux could explain the signals seen at DAMA/LIBRA, CDMS/Si and CoGeNT consistently with the bounds from XENON100 and CDMS/Ge. To explore the plausibility of this scenario, we discuss a concrete model with 10–50 MeV sterile neutrinos that was recently proposed to explain the LSND and MiniBooNE anomalies.

In this article, the long-distance correction to the total decay width of the ${\tau }^{\pm }\to K^0{\pi }^{\pm }\nu$ decay is calculated in a model-independent approach, in which a discrimination of photons in the bremmstrahlung process is assumed. This correction is completely free of ultraviolet and infrared singularities, and, moreover, it satisfies electromagnetic gauge invariance. The result of this work can be applied on the tau decays: ${\tau }^{\pm }\to {\pi }^{\pm }{\pi }^0\nu$, $K^{\pm }{\pi }^0\nu$.

We present the results of global analyses of short-baseline neutrino oscillation data in $3+1$, $3+2$ and $3+1+1$ neutrino mixing schemes. We show that the data do not allow us to abandon the simplest $3+1$ scheme in favor of the more complex $3+2$ and $3+1+1$ schemes. We present the allowed region in the $3+1$ parameter space, which is located at $\Delta m_{41}^2$ between 0.82 and $2.19{\mathrm{eV}}^2$ at $3\sigma$. The case of no oscillations is disfavored by about $6\sigma$, which decreases dramatically to about $2\sigma$ if the Liquid Scintillating Neutrino Detector (LSND) data are not considered. Hence, new high-precision experiments are needed to check the LSND signal.

The firewall paradox is often presented as arising from double entanglement, but I argue that more generally the paradox is double purity. Near-horizon modes are purified by the interior, in the infalling vacuum. Hence, they cannot also be pure alone, or in combination with any third system, as demanded by unitarity. This conflict arises independently of the Page time, for entangled and for pure states. It implies that identifications of Hilbert spaces cannot resolve the paradox. Traditional complementarity requires the unitary identification of infalling matter with a scrambled subsystem of the Hawking radiation. Extending this map to the infalling vacuum overdetermines the out-state. More general complementarity maps (“$A=R_B$,” “$\mathrm{ER}=\mathrm{EPR}$”) necessarily fail when the near-horizon zone is pure. I argue that pure-zone states span the microcanonical ensemble, and that this suffices to make the horizon a special place. I advocate that the ability to detect the horizon locally, rather than the degree or probability of violence, is what makes firewalls problematic. Conversely, if the production of matter at the horizon can be dynamically understood and shown to be consistent, then firewalls do not constitute a violation of the equivalence principle.

Using the correspondence between the $f(T)$-gravity model and the holographic dark energy model with the power-law entropy correction, we reconstruct the holographic $f(T)$-gravity model with the power-law entropy correction. We fit the model parameters by using the latest observational data including type Ia supernovae, baryon acoustic oscillations, cosmic microwave background, and Hubble parameter data. We also check the viability of our model using a cosmographic analysis approach. Using the best-fit values of the model, we obtain the evolutionary behavior of the effective torsion equation-of-state parameter of the power-law entropy-corrected holographic $f(T)$-gravity model, as well as the deceleration parameter of the Universe. We also investigate different energy conditions in our model. Furthermore, we examine the validity of the generalized second law of gravitational thermodynamics. Finally, we point out the growth rate of the matter density perturbation in our model. We conclude that in the power-law entropy-corrected holographic $f(T)$-gravity model, the Universe begins a matter-dominated phase and approaches a de Sitter regime at late times, as expected. It also can justify the transition from the quintessence state to the phantom regime in the near past, as indicated by recent observations. Moreover, this model is consistent with current data, it passes the cosmographic test, and it fits the data of the growth factor as well as the $\Lambda \mathrm{CDM}$ model.

We present constraints on a cosmic string network with a measurement of weak gravitational lensing from CMB temperature map. The cosmic string network between the observer and last scattering surface of CMB photons generates vector and/or tensor metric perturbations, and the deflection of CMB photons by these gravitational fields has a curl mode which is not produced by the scalar metric perturbations. In this paper, we use the power spectrum of curl mode obtained from Planck to constrain the string tension, $G\mu$, and the reconnection probability, $P$. In demonstrating the parameter constraints with Planck curl mode, we also measure the lensing power spectrum from the Atacama Cosmology Telescope (ACT) 2008 season data, which have better angular resolution with lower instrumental noise on a much smaller chunk of the sky. Assuming $P=1$, the upper bound on tension is $G\mu =6.6\times {10}^{-5}$ with $2\sigma$ (95% C.L.), using curl mode from Planck, which is weaker than that from the small-scale temperature power spectrum. For small values of $P$, however, the constraint from curl mode becomes tighter compared to that from the temperature power spectrum. For $P\lesssim {10}^{-2}$, we obtain the constraint on the combination of the string parameters as $G\mu P^{-1}\le 3.4\times {10}^{-5}$ at more than $2\sigma$ (95% C.L.).

Measuring the small primordial non-Gaussianity (PNG) predicted by cosmic inflation theories may help diagnose them. The detectability of PNG by its imprint on the 21 cm power spectrum from the epoch of reionization is reassessed here in terms of $f_{\mathrm{NL}}$, the local nonlinearity parameter. We find that an optimum, multifrequency observation by SKA can achieve $\Delta f_{\mathrm{NL}}\sim 3$ (comparable to recent Planck CMB limits), while a cosmic-variance-limited array of this size like Omniscope can even detect $\Delta f_{\mathrm{NL}}\sim 0.2$. This substantially revises the methods and results of previous work.

Many particle physics analyses which need to discriminate some background process from a signal ignore event-by-event resolutions of kinematic variables. Adding this information, as is done for missing momentum significance, can only improve the power of existing techniques. We therefore propose the use of significance variables which combine kinematic information with event-by-event resolutions. We begin by giving some explicit examples of constructing optimal significance variables. Then, we consider three applications: new heavy gauge bosons, Higgs to $\tau \tau$, and direct stop squark pair production. We find that significance variables can provide additional discriminating power over the original kinematic variables: $\sim 20\%$ improvement over $m_T$ in the case of $H\to \tau \tau$, and $\sim 30\%$ improvement over $m_{T2}$ in the case of the direct stop search.

We revisit the possibility that the top quark forward-backward asymmetry arises from the on-shell production and decay of scalar top partners to $t\overline{t}+{\mathrm{E̸}}_T$. Although the asymmetry is produced by $t$-channel exchange of a light mediator, the model remains unconstrained by low energy atomic parity violation tests. An interesting connection to the active neutrino sector through a type-I seesaw operator helps to evade stringent monojet constraints and opens up a richer collider phenomenology. After performing a global fit to top data from both the Tevatron and the LHC, we obtain a viable region of parameter space consistent with all phenomenological and collider constraints. We also discuss the discovery potential of a predicted monotop signal and related lepton charge asymmetry at the LHC.

We explore phenomenological implications of the minimal supersymmetric standard model (MSSM) with a strong supersymmetry-breaking trilinear term. Supersymmetry breaking can trigger electroweak symmetry breaking via a symmetry-breaking seesaw mechanism, which can lead to a low-energy theory with multiple composite Higgs bosons. In this model, the electroweak phase transition can be first order for some generic values of parameters. Furthermore, there are additional sources of $CP$ violation in the Higgs sector. This opens the possibility of electroweak baryogenesis in the strongly coupled MSSM. The extended Higgs dynamics can be discovered at the Large Hadron Collider or at a future linear collider.

We explore the possibility of experimentally detecting a predicted $h_1[I^G(J^{PC})=0^{-}(1^{+-})]$ state of hidden charm made out from the $D^{*}{\overline{D}}^{*}$ interaction. The method consists in measuring the decay of $X(4660)$ into $\eta D^{*}{\overline{D}}^{*}$ and determining the binding energy with respect to the $D^{*}{\overline{D}}^{*}$ threshold from the shape of the $D^{*}{\overline{D}}^{*}$ invariant mass distribution. A complementary method consists in looking at the inclusive $X(4660)\to \eta X$ decay and searching for a peak in the $X$ invariant mass distribution. We make calculations to determine the partial decay width of $X(4660)\to \eta h_1$ from the measured $X(4660)\to \eta D^{*}{\overline{D}}^{*}$ distribution. This estimation should serve in an experiment to foresee the possibility of detecting the $h_1$ state on top of the background of inclusive events.

We present a new tool for precision measurements of the Higgs boson production mechanisms at the LHC. We study events with a Higgs boson produced with two forward jets. Even with fairly stringent cuts, one expects a significant contamination of gluon fusion (GF) in addition to vector-boson fusion (VBF) in the event sample. By measuring the jet energy profile of the most central jet, we find that SM production can be distinguished from either pure VBF or pure GF at the $5\sigma$ level with $100{\mathrm{fb}}^{-1}$ of luminosity at the 14 TeV LHC. Moreover, this discrimination technique can be used to validate or rule out new physics models that predict similar observable branching fractions as the 125 GeV Standard Model Higgs boson but have different production mechanisms.

In some quantum theories of gravity, deviations from the laws of relativity could be comparatively large while escaping detection to date. In the neutrino sector, precision experiments with beta decay yield new and improved constraints on these countershaded relativity violations. Existing data are used to extract bounds of $3\times {10}^{-8}\mathrm{GeV}$ on the magnitudes of two of the four possible coefficients, and estimates are provided of future attainable sensitivities in a variety of experiments.

We derive the energy of pulsating strings, as a function of oscillation number and angular momenta, which oscillates in ${\mathrm{AdS}}_3$ with an extra angular momentum along ${\mathrm{S}}^1$. We find similar solutions for the strings oscillating in ${\mathrm{S}}^3$ in addition to extra angular momentum. Furthermore, we generalize the result of the oscillating strings in anti–de Sitter space in the presence of both spin and angular momentum in ${\mathrm{AdS}}_5\times {\mathrm{S}}_1$.