We revisit the effect of cosmological constant $\Lambda$ on the light deflection and its role in the cosmological lens equation. First, we reexamine the motion of photon in the Schwarzschild spacetime, and explicitly describe the trajectory of photon and deflection angle $\alpha$ up to the second order in $G$. Then the discussion is extended to the contribution of the cosmological constant $\Lambda$ in the Schwarzschild-de Sitter or Kottler spacetime. Contrary to the previous arguments, we emphasize the following points: (a) the cosmological constant $\Lambda$ does appear in the orbital equation of light, (b) nevertheless the bending angle of light $\alpha$ does not change its form even if $\Lambda \ne 0$ since the contribution of $\Lambda$ is thoroughly absorbed into the definition of the impact parameter, and (c) the effect of $\Lambda$ is completely involved in the angular diameter distance $D_A$.

The Planck Collaboration measured the Sunyaev-Zel’dovich decrement of optically selected clusters from the Sloan Digital Sky Survey, finding that it falls significantly below expectations based on existing mass calibration of the maxBCG galaxy clusters. Resolving this tension requires either the data to go up, or the theoretical expectations to come down. Here, we use data from the Wilkinson Microwave Anisotropy Probe to perform an independent estimate of the Sunyaev-Zel’dovich decrement of maxBCG clusters. The recovered signal is consistent with that obtained using the Planck satellite, though with larger error bars due to the Wilkinson Microwave Anisotropy Probe’s larger beam size and smaller frequency range. Nevertheless, this detection serves as an independent confirmation of the magnitude of the effect, and demonstrates that the observed discrepancy must originate in modeling or other systematic uncertainties.

The spectrum of an isotropic extragalactic $\gamma$-ray background (EGB) has been measured by the Fermi-LAT telescope at high latitudes. Two new models for the EGB are derived from the subtraction of unresolved point sources and extragalactic diffuse processes, which could explain from 30% to 70% of the Fermi-LAT EGB. Within the hypothesis that the two residual EGBs are entirely due to the annihilation of dark matter (DM) particles in the Galactic halo, we obtain stringent upper limits on their annihilation cross section. Severe bounds on a possible Sommerfeld enhancement of the annihilation cross section are set as well. Finally, we consider models for DM annihilation depending on the inverse of the velocity and associate the EGBs to photons arising from the annihilation of DM in primordial halos. Given our choices for the EGB and the minimal DM modeling, the derived upper bounds are claimed to be conservative.

Motivated by the recent interest in light weakly interacting massive particles (WIMPs) of mass $\sim \mathcal{O}(10\mathrm{GeV}/c^2)$, an extension of the elastic, spin-independent, WIMP-nucleon cross-section limits resulting from the CRESST-II commissioning run (2007) are presented. Previously, these data were used to set cross-section limits from $1000\mathrm{GeV}/c^2$ down to $\sim 17\mathrm{GeV}/c^2$, using tungsten recoils, in 47.9 kg-days of exposure of calcium tungstate. Here, the overlap of the oxygen and calcium bands with the acceptance region of the commissioning run data set is reconstructed using previously published quenching factors. The resulting elastic WIMP cross-section limits, accounting for the additional exposure of oxygen and calcium, are presented down to $5\mathrm{GeV}/c^2$.

A general electroweak scale $Z^{\prime }$ is applied in a supersymmetric $\mathrm{SU}(6)\times \mathrm{SU}(2{)}_h$ grand unification model, to have a ${\mathbb{Z}}_6$ for the hexality. We briefly show that there cannot exist any baryonic $\mathrm{U}(1{)}_B^{\prime }$ in any subgroup of ${\mathrm{E}}_6$. Any effect that requires sizable $Z^{\prime }$ couplings to quarks like the reported $Wjj$ anomaly of CDF, if observed, implies a substantial $Z^{\prime }$ coupling to leptons or Higgs doublets. The kinetic mixing considered in a supersymmetric model from ${\mathrm{E}}_6$ is restricted by the gauge coupling unification and neutrino mixing. The mass of $Z^{\prime }$ is strongly constrained by the electroweak ${\rho }_0$ parameter. We conclude that a $Z^{\prime }$ mass much above 10 TeV is favored by considering the neutrino mixing and proton decay constraint in supersymmetric models. In this sense, the CDF $Wjj$ anomaly cannot be fitted to any electroweak model descending from ${\mathrm{E}}_6$. Furthermore, if $Z^{\prime }$ is found at several hundred GeV, any grand unification group embedded in ${\mathrm{E}}_6$ such as $\mathrm{SU}(6)\times \mathrm{SU}(2)$, SO(10), $\mathrm{SU}(5)\times \mathrm{U}(1)$, SU(5), $\mathrm{SU}(4)\times \mathrm{SU}(4)$, and $\mathrm{SU}(3{)}^3$, needs fine-tuned gauge couplings. We also discuss the $\mathrm{U}(1{)}^{\prime }$ effect on the tree level mass of the lightest MSSM Higgs boson.

We reconsider the $\lambda \mathrm{SUSY}$ model, in which the mass of the Higgs boson is raised already at tree level up to about 200 GeV via an additional interaction in the superpotential between the Higgs bosons and a singlet, focusing on a scale invariant superpotential. After a detailed analysis of the allowed region in parameter space, which includes constraints coming from the absence of spontaneous $CP$ violation and of unrealistic minima, we study the scalar mass spectrum, the production rate, and the decay modes of the lightest scalar, finding that, in general, both the production rate and the branching ratio into gauge bosons can be reduced with respect to those of the standard Higgs, causing it to be hardly detected in the first run of the LHC.

The kinematic edges of invariant-mass distributions provide an important tool for the possible measurements of superpartner masses in supersymmetric models with a neutralino lightest supersymmetric particle. We examine the effect of lepton flavor dependence on the kinematic endpoints of the dilepton invariant-mass distribution, with the leptons being electrons and muons. In the presence of slepton mass splitting and mixing, each of these distributions exhibits multiple edges, which are likely to be close. Furthermore, flavor subtraction, which is usually employed to eliminate backgrounds, dilutes the signal. We propose to extract the endpoints from the flavor-added distribution, which is insensitive to the slepton mixing. We also discuss the extraction of the slepton flavor parameters in such scenarios. To demonstrate our results, we use an example with a small slepton mass splitting of 3 GeV leading to a 6 GeV edge splitting, at both small mixing and large mixing.

Current limits from the Large Hadron Collider exclude a standard model-like Higgs mass above 150 GeV, by placing an upper bound on the Higgs production rate. We emphasize that, alternatively, the limit could be interpreted as a lower bound on the total decay width of the Higgs boson. If the invisible decay width of the Higgs is of the same order as the visible decay width, a heavy Higgs boson could be consistent with null results from current searches. We propose a method to infer the invisible decay of the Higgs by using the width of the measured $h\to ZZ\to 4\ell$ line shape, and study the effect on the width extraction due to a reduced signal strength. Assuming the invisible decay product is the dark matter, we show that minimal models are tightly constrained by limits from Higgs searches at the LHC and direct detection experiments of dark matter, unless the relic density constraint is relaxed.

We revisit the cosmology of the supersymmetric QCD axion, highlighting the existence of a serious cosmological axino problem that is fully analogous to the gravitino problem of overclosure via thermal production. A general analysis implies that the QCD axino has a mass greater than or equal to that of the gravitino in the absence of unnatural fine-tuning or sequestering. As a consequence, bounds from thermal gravitino and QCD axino production are complementary in parameter space, and together provide a quite stringent limit on the reheating temperature after inflation given by $T_R<{10}^3-{10}^6\mathrm{GeV}$ for an axion decay constant of $f_a={10}^9-{10}^{12}\mathrm{GeV}$. Motivated by this result, we explore the cosmology of gravitino lightest supersymmetric particle and axino next to lightest supersymmetric particle at low $T_R$ and present three realistic scenarios for dark matter.

The exclusive $B\to K_2{\ell }^{+}{\ell }^{-}$ decay is studied using the most general, model independent four–fermion interaction. The sensitivity of the ratio of the decay widths when $K_2$ meson is longitudinally and transversally polarized, the forward-backward asymmetry and longitudinal polarization of the final lepton on the new Wilson coefficients is studied. It is found that these quantities are very useful for establishing new physics beyond the standard model.

Using the model of Nambu and Jona-Lasinio to provide a microscopic description of both the structure of the nucleon and of the quark to hadron elementary fragmentation functions, we investigate the transverse-momentum dependence of the unpolarized quark distributions in the nucleon and of the quark to pion and kaon fragmentation functions. The transverse-momentum dependence of the fragmentation functions is determined within a Monte Carlo framework, with the notable result that the average $P_{\perp }^2$ of the produced kaons is significantly larger than that of the pions. We also find that $⟨P_{\perp }^2⟩$ has a sizable $z$ dependence, in contrast with the naive Gaussian ansatz for the fragmentation functions. Diquark correlations in the nucleon give rise to a nontrivial flavor dependence in the unpolarized transverse-momentum-dependent quark distribution functions. The $⟨k_T^2⟩$ of the quarks in the nucleon are also found to have a sizable $x$ dependence. Finally, these results are used as input to a Monte Carlo event generator for semi-inclusive deep inelastic scattering (SIDIS), which is used to determine the average transverse momentum squared of the produced hadrons measured in SIDIS, namely, $⟨P_T^2⟩$. Again, we find that the average $P_T^2$ of the produced kaons in SIDIS is significantly larger than that of the pions and in each case $⟨P_T^2⟩$ has a sizable $z$ dependence.

We calculate the set of $O({\alpha }_s)$ corrections to the double differential decay width $d{\Gamma }_{77}/(d{s}_{1}d{s}_2)$ for the process $\overline{B}\to X_s\gamma \gamma$ originating from diagrams involving the electromagnetic dipole operator ${\mathcal{O}}_7$. The kinematical variables $s_1$ and $s_2$ are defined as $s_i=(p_b-q_i{)}^2/m_b^2$, where $p_b$, $q_1$, and $q_2$ are the momenta of the $b$ quark and two photons. While the (renormalized) virtual corrections are worked exactly for a certain range of $s_1$ and $s_2$, we retain in the gluon bremsstrahlung process only the leading power with respect to the (normalized) hadronic mass $s_3=(p_b-q_1-q_2{)}^2/m_b^2$ in the underlying triple differential decay width $d{\Gamma }_{77}/(d{s}_{1}d{s}_{2}d{s}_3)$. The double differential decay width, based on this approximation, is free of infrared and collinear singularities when combining virtual and bremsstrahlung corrections. The corresponding results are obtained analytically. When retaining all powers in $s_3$, the sum of virtual and bremsstrahlung corrections contains uncanceled $1/ϵ$ singularities (which are due to collinear photon emission from the $s$ quark), and other concepts, which go beyond perturbation theory, such as parton fragmentation functions of a quark or a gluon into a photon, are needed which is beyond the scope of our paper.

The stability of systems containing six quarks or antiquarks is studied within a simple string model inspired by the strong-coupling regime of quantum chromodynamics and used previously for tetraquarks and pentaquarks. We discuss both six-quark ($q^6$) and three-quark–three-antiquark ($q^3{\overline{q}}^3$) states. The quarks are assumed to be distinguishable and thus not submitted to antisymmetrization. It is found that the ground state of ($q^6$) is stable against dissociation into two isolated baryons. For the case of ($q^3{\overline{q}}^3$), our results indicate the existence of a bound state very close to the threshold. The investigations are extended to ($q^3{Q}^3$) and ($Q^3{\overline{q}}^3$) systems with two different constituent masses, and their stability is discussed as a function of the mass ratio.

The gauge-invariant generation of an effective gluon mass proceeds through the well-known Schwinger mechanism, whose key dynamical ingredient is the nonperturbative formation of longitudinally coupled massless bound-state excitations. These excitations introduce poles in the vertices of the theory, in such a way as to maintain the Slavnov-Taylor identities intact in the presence of massive gluon propagators. In the present work we first focus on the modifications induced to the nonperturbative three-gluon vertex by the inclusion of massless two-gluon bound states into the kernels appearing in its skeleton expansion. Certain general relations between the basic building blocks of these bound states and the gluon mass are then obtained from the Slavnov-Taylor identities and the Schwinger-Dyson equation governing the gluon propagator. The homogeneous Bethe-Salpeter equation determining the wave function of the aforementioned bound state is then derived, under certain simplifying assumptions. It is then shown, through a detailed analytical and numerical study, that this equation admits nontrivial solutions, indicating that the QCD dynamics support indeed the formation of such massless bound states. These solutions are subsequently used, in conjunction with the aforementioned relations, to determine the momentum-dependence of the dynamical gluon mass. Finally, further possibilities and open questions are briefly discussed.

The charged-current antikaon production off nucleons induced by antineutrinos is studied at low and intermediate energies. We extend here our previous calculation on kaon production induced by neutrinos. We have developed a microscopic model that starts from the SU(3) chiral Lagrangians and includes background terms and the resonant mechanisms associated to the lowest lying resonance in the channel, namely, the ${\Sigma }^{*}(1385)$. Our results could be of interest for the background estimation of various neutrino oscillation experiments like MiniBooNE and SuperK. They can also be helpful for the planned $\overline{\nu }$ experiments like $\mathrm{MINER}\nu \mathrm{A}$, $\mathrm{NO}\nu \mathrm{A}$, and T2K phase II, and for beta-beam experiments with antineutrino energies around 1 GeV.

We present an update of a search for supersymmetry in final states containing jets, missing transverse momentum, and one isolated electron or muon, using $1.04{\mathrm{fb}}^{-1}$ of proton-proton collision data at $\sqrt{s}=7\mathrm{TeV}$ recorded by the ATLAS experiment at the LHC in the first half of 2011. The analysis is carried out in four distinct signal regions with either three or four jets and variations on the (missing) transverse momentum cuts, resulting in optimized limits for various supersymmetry models. No excess above the standard model background expectation is observed. Limits are set on the visible cross section of new physics within the kinematic requirements of the search. The results are interpreted as limits on the parameters of the minimal supergravity framework, limits on cross sections of simplified models with specific squark and gluino decay modes, and limits on parameters of a model with bilinear $R$-parity violation.

This paper describes a measurement of the $W$ boson transverse momentum distribution using ATLAS $pp$ collision data from the 2010 run of the LHC at $\sqrt{s}=7\mathrm{TeV}$, corresponding to an integrated luminosity of about $31{\mathrm{pb}}^{-1}$. Events form both $W\to e\nu$ and $W\to \mu \nu$ are used, and the transverse momentum of the $W$ candidates is measured through the energy deposition in the calorimeter from the recoil of the $W$. The resulting distributions are unfolded to obtain the normalized differential cross sections as a function of the $W$ boson transverse momentum. We present results for $p_T^W<300\mathrm{GeV}$ in the electron and muon channels as well as for their combination, and compare the combined results to the predictions of perturbative QCD and a selection of event generators.

Data from the Liquid Scintillator Neutrino Detector and Mini-Booster Neutrino experiments, and the revised expectations of the antineutrino flux from nuclear reactors suggest the existence of eV-mass sterile neutrinos. The $3+2$ and $1+3+1$ scenarios accommodate all relevant short-baseline neutrino data except for the low-energy Mini-Booster Neutrino Experiment anomaly. We analyze the angular distribution of upward going atmospheric neutrino events in the IceCube-40 data set for evidence of sterile neutrinos within these scenarios. Depending on how systematic uncertainties are handled, we find strong evidence for, or weak evidence against sterile neutrinos. We show that future IceCube data will definitively settle the issue.

We use gauge-gravity duality to study the temperature dependence of the zero sound mode and the fundamental matter diffusion mode in the strongly coupled $\mathcal{N}=4$ $SU(N_c)$ supersymmetric Yang-Mills theory with $N_f$ $\mathcal{N}=2$ hypermultiplets in the $N_c\gg 1$, $N_c\gg N_f$ limit, which is holographically realized via the D3/D7 brane system. In the high density limit $\mu \gg T$, three regimes can be identified in the behavior of these modes, analogous to the collisionless quantum, collisionless thermal, and hydrodynamic regimes of a Landau Fermi liquid. The transitions between the three regimes are characterized by the parameters $T/\mu$ and $(T/\mu {)}^2$, respectively, and in each of these regimes the modes have a distinctively different temperature and momentum dependence. The collisionless-hydrodynamic transition occurs when the zero sound poles of the density-density correlator in the complex frequency plane collide on the imaginary axis to produce a hydrodynamic diffusion pole. We observe that the properties characteristic of a Landau Fermi-liquid zero sound mode are present in the D3/D7 system despite the atypical $T^6/{\mu }^3$ temperature scaling of the specific heat and an apparent lack of a directly identifiable Fermi surface.

The restriction to invariant connections in a Friedmann-Robertson-Walker space-time is discussed via the analysis of the Dirac brackets associated with the corresponding gauge-fixing. This analysis allows us to establish the proper correspondence between reduced and unreduced variables. In this respect, it is outlined how the holonomy-flux algebra coincides with the one of Loop Quantum Gravity if edges are parallel to simplicial vectors and the quantization of the model is performed via standard techniques by restricting admissible paths. Within this scheme, the discretization of the area spectrum is emphasized. Then, the role of the diffeomorphisms generator in reduced phase-space is investigated and it is clarified how it implements homogeneity on quantum states, which are defined over cubical knots. Finally, the perspectives for a consistent dynamical treatment are discussed.