We study a simple, well-motivated model based on a custodial symmetry which describes the tree-level production of a 750 GeV diphoton resonance from a decay of a singly produced vector-like quark. The model has several novel features. The identification of the resonance as an ${\mathrm{SU}(2)}_R$ triplet provides a symmetry explanation for suppression of its decays to $hh$, $WW$, and $gg$. Moreover, the ratio of the 13 TeV to 8 TeV cross sections can be larger than single production of a 750 GeV resonance, reaching ratios of up to 7 for TeV scale vectorlike quark masses. This eliminates any tension between the results from Run I and Run II diphoton searches. Lastly, we study the kinematics of our signal and conclude that the new production mechanism is consistent with available experimental distributions in large regions of parameter space but, depending on the mass of the new vectorlike quarks, can be differentiated from the background with more statistics.

In this exploratory lattice study, low-energy near threshold scattering of the $({\overline{D}}_1{D}^{*}{)}^{\pm }$ meson system is analyzed using lattice QCD with $N_f=2$ twisted mass fermion configurations. Both s-wave ($J^P=0^{-}$) and p-wave ($J^P=1^{+}$) channels are investigated. It is found that the interaction between the two charmed mesons is attractive near the threshold in both channels. This calculation provides some hints in the searching of resonances or bound states around the threshold of $({\overline{D}}_1{D}^{*}{)}^{\pm }$ system.

We measure the forward-backward asymmetries $A_{\mathrm{FB}}$ of charged $\mathrm{\Xi }$ and $\mathrm{\Omega }$ baryons produced in $p\overline{p}$ collisions recorded by the D0 detector at the Fermilab Tevatron collider at $\sqrt{s}=1.96\mathrm{TeV}$ as a function of the baryon rapidity $y$. We find that the asymmetries $A_{\mathrm{FB}}$ for charged $\mathrm{\Xi }$ and $\mathrm{\Omega }$ baryons are consistent with zero within statistical uncertainties.

In this paper, based on the fundamental principles of gauge/gravity duality and considering a global quench, we probe the physics of thermalization for certain special classes of strongly coupled nonrelativistic quantum field theories that are dual to an asymptotically Schrödinger $Dp$ brane space time. In our analysis, we note that during the prelocal stages of the thermal equilibrium the entanglement entropy has a faster growth in time compared to its relativistic cousin. However, it shows a linear growth during the postlocal stages of thermal equilibrium where the so-called tsunami velocity associated with the linear growth of the entanglement entropy saturates to that of its value corresponding to the relativistic scenario. Finally, we explore the saturation region and it turns out that one must constraint certain parameters of the theory in a specific way in order to have discontinuous transitions at the point of saturation.

We study radiation emitted by a time-dependent source of a scalar massless field in the framework of the ghost-free modifications of the theory. We consider a simple model of the emitter: namely, we assume that it is point-like and monochromatic. We focus on the most common versions of the ghost-free theory, where the propagator ${\square }^{-1}$ is modified as follows: $\exp (-(\square /{\mu }^2{)}^N){\square }^{-1}$, where $\mu$ is the characteristic mass scale of such a $G{F}_N$ theory. We demonstrate that far from the source, in the wave zone, the radiation asymptotically converges to its “classical” value for any $N\ge 1$. However, in the near zone the behavior of the field is quite different from the “classical” case. The difference of the field amplitude for the ghost-free field and for the classical one has an oscillatory behavior in this domain. The number of oscillations increases with $N$. The amplitude of these oscillations remains finite for even $N$, while it infinitely grows with frequency for odd $N$. This behavior indicates that even in the classical domain $G{F}_N$ theories might have pathological behavior.

It is shown how to obtain conformal blocks from embedding space with the help of the operator product expansion. The minimal conformal block originates from scalar exchange in a four-point correlation function of four scalars. All remaining conformal blocks are simple derivatives of the minimal conformal block. With the help of the orthogonality properties of the conformal blocks, the analytic conformal bootstrap can be implemented directly in embedding space, leading to a Jacobi-like definition of conformal field theories.

An axiomatic approach to electrodynamics reveals that Maxwell electrodynamics is just one instance of a variety of theories for which the name electrodynamics is justified. They all have in common that their fundamental input are Maxwell’s equations $\mathrm{d}F=0$ (or $F=\mathrm{d}A$) and $\mathrm{d}H=J$ and a constitutive law $H=\#F$ which relates the field strength two-form $F$ and the excitation two-form $H$. A local and linear constitutive law defines what is called local and linear pre-metric electrodynamics whose best known application is the effective description of electrodynamics inside media including, e.g., birefringence. We analyze the classical theory of the electromagnetic potential $A$ before we use methods familiar from mathematical quantum field theory in curved spacetimes to quantize it in a locally covariant way. Our analysis of the classical theory contains the derivation of retarded and advanced propagators, the analysis of the causal structure on the basis of the constitutive law (instead of a metric) and a discussion of the classical phase space. This classical analysis sets the stage for the construction of the quantum field algebra and quantum states. Here one sees, among other things, that a microlocal spectrum condition can be formulated in this more general setting.

Several models of gamma-ray burst progenitors suggest that the gamma-ray event may be followed by gravitational wave signals of $10^3–10^4\mathrm{s}$ duration (possibly accompanying the so-called x-ray afterglow “plateaus”). We term these signals “intermediate duration” because they are shorter than continuous wave signals but longer than signals traditionally considered as gravitational wave bursts and are difficult to detect with most burst and continuous wave methods. The cross-correlation technique proposed by [S. Dhurandhar et al., Phys. Rev. D 77, 082001 (2008)], which so far has been used only on continuous wave signals, in principle unifies both burst and continuous wave (as well as matched filtering and stochastic background) methods, reducing them to different choices of which data to correlate on which time scales. Here, we perform the first tuning of this cross-correlation technique to intermediate-duration signals. We derive theoretical estimates of sensitivity in Gaussian noise in different limits of the cross-correlation formalism and compare them to the performance of a prototype search code on simulated Gaussian-noise data. We estimate that the code is likely able to detect some classes of intermediate-duration signals (such as the ones described in [A. Corsi and P. Mészáros, Astrophys. J. 702, 1171 (2009)]) from sources located at astrophysically relevant distances of several tens of Mpc.

Apart from the known weak gravitational lensing effect, the cosmic magnification acquires relativistic corrections owing to Doppler, integrated Sachs-Wolfe, time-delay and other (local) gravitational potential effects, respectively. These corrections grow on very large scales and high redshifts $z$, which will be the reach of forthcoming surveys. In this work, these relativistic corrections are investigated in the magnification angular power spectrum, using both (standard) noninteracting dark energy (DE), and interacting DE (IDE). It is found that for noninteracting DE, the relativistic corrections can boost the magnification large-scale power by $\sim 40\%$ at $z=3$, and increases at lower $z$. It is also found that the IDE effect is sensitive to the relativistic corrections in the magnification power spectrum, particularly at low $z$—which will be crucial for constraints on IDE. Moreover, the results show that if relativistic corrections are not taken into account, this may lead to an incorrect estimate of the large-scale imprint of IDE in the cosmic magnification; including the relativistic corrections can enhance the true potential of the cosmic magnification as a cosmological probe.

We investigate the statistical power of higher-order statistics and cross-correlation statistics to constrain the primordial non-Gaussianity from the imaging surveys. In particular, we consider the local-type primordial non-Gaussianity and discuss how well one can tightly constrain the higher-order non-Gaussian parameters ($g_{\mathrm{NL}}$ and ${\tau }_{\mathrm{NL}}$) as well as the leading-order parameter $f_{\mathrm{NL}}$ from the halo/galaxy clustering and weak gravitational lensing measurements. Making use of a strong scale-dependent behavior in the galaxy/halo clustering, Fisher matrix analysis reveals that the bispectra can break the degeneracy between non-Gaussian parameters ($f_{\mathrm{NL}}$, $g_{\mathrm{NL}}$ and ${\tau }_{\mathrm{NL}}$), and this will give simultaneous constraints on those three parameters. The combination of cross-correlation statistics further improves the constraints by a factor of 2. As a result, upcoming imaging surveys like the Large Synoptic Survey Telescope have the potential to improve the constraints on the primordial non-Gaussianity much tighter than those obtained from the CMB measurement by Planck, giving us an opportunity to test the single-sourced consistency relation, ${\tau }_{\mathrm{NL}}\ge (36/25)f_{\mathrm{NL}}^2$.

We explore the phenomenology of a class of models where the dark matter particle can inelastically up-scatter to a heavier excited state via off-diagonal dipolar interactions with the interstellar plasma (gas or free electrons). The heavier particle then rapidly decays back to the dark matter particle plus a quasimonochromatic photon. For the process to occur at appreciable rates, the mass splitting between the heavier state and the dark matter must be comparable to, or smaller than, the kinetic energy of particles in the plasma. As a result, the predicted photon line falls in the soft x-ray range, or, potentially, at arbitrarily lower energies. We explore experimental constraints from cosmology and particle physics, and present accurate calculations of the dark matter thermal relic density and of the flux of monochromatic x rays from thermal plasma excitation. We find that the model provides a natural explanation for the observed 3.5 keV line from clusters of galaxies and from the Galactic center, and is consistent with null detections of the line from dwarf galaxies. The unique line shape, which will be resolved by future observations with the Hitomi (formerly Astro-H) satellite, and the predicted unique morphology and target-temperature dependence will enable easy discrimination of this class of models versus other scenarios for the generation of the 3.5 keV line or of any other unidentified line across the electromagnetic spectrum.

Supersymmetric standard models (SSMs) with Dirac gauginos have the appealing supersoft property that they only cause finite contributions to scalar masses. Considering gauge mediated SUSY breaking with conformal sequestering and assuming there is one and only one fundamental parameter with dimension mass arising from supersymmetry breaking, we find a cancellation between the dominant terms that contribute to the electroweak fine tuning (EWFT). The resulting EWFT measure can be of order one even for supersymmetric particle masses and $\mu$-terms in the TeV range.

We study the detectability of the stoponium in the di-Higgs decay mode at the photon-photon collider option of the International $e^{+}{e}^{-}$ Linear Collider, the center-of-mass energy of which is planned to reach $\sim 1\mathrm{TeV}$. We find that $5\sigma$ detection of the di-Higgs decay mode is possible with the integrated electron-beam luminosity of $1{\mathrm{ab}}^{-1}$ if the signal cross section, $\sigma (\gamma \gamma \to {\sigma }_{{\tilde{t}}_1}\to hh)$, of $\mathcal{O}(0.1)\mathrm{fb}$ is realized for the stoponium mass smaller than $\sim 800\mathrm{GeV}$ at 1 TeV ILC. Such a value of the cross section can be realized in the minimal supersymmetric standard model with relatively large trilinear stop-stop-Higgs coupling constant. The implication of the stoponium cross section measurement for the minimal supersymmetric standard model stop sector is also discussed.

Observable primordial tensor modes in the cosmic microwave background (CMB) would point to a high scale of inflation $H_I$. If the scale of Peccei-Quinn (PQ) breaking $f_a$ is greater than $\frac{H_I}{2\pi }$, CMB constraints on isocurvature naively rule out QCD axion dark matter. This assumes the potential of the axion is unmodified during inflation. We revisit models where inflationary dynamics modify the axion potential and discuss how isocurvature bounds can be relaxed. We find that models that rely solely on a larger PQ-breaking scale during inflation $f_I$ require either late-time dilution of the axion abundance or highly super-Planckian $f_I$ that somehow does not dominate the inflationary energy density. Models that have enhanced explicit breaking of the PQ symmetry during inflation may allow $f_a$ close to the Planck scale. Avoiding disruption of inflationary dynamics provides important limits on the parameter space.

We introduce a simple scenario involving fermionic dark matter ($\chi$) and singlet scalar mediators that may account for the Galactic center GeV $\gamma$-ray excess while satisfying present direct detection constraints. $CP$ violation in the scalar potential leads to a mixing between the Standard Model Higgs boson and the scalar singlet, resulting in three scalars, $h_{1,2,3}$, of indefinite $CP$-transformation properties. This mixing enables $s$-wave $\chi \overline{\chi }$ annihilation into discalar states, followed by decays into four-fermion final states. The observed $\gamma$-ray spectrum can be fitted while respecting present direct detection bounds and Higgs boson properties for $m_{\chi }=60\sim 80\mathrm{GeV}$, and $m_{h_3}\sim m_{\chi }$. Searches for the Higgs exotic decay channel $h_1\to h_3{h}_3$ at the 14 TeV LHC should be able to further probe the parameter region favored by the $\gamma$-ray excess.

Momentum space anisotropy present in the quark and gluon distribution functions in relativistic heavy ion collisions induces Chromo-Weibel instability in the hot QCD medium created therein. The impact of the Chromo-Weibel instability on the dynamics of a heavy quark (HQ) traversing in the QGP medium is investigated within the framework of kinetic theory by studying the momentum and temperature behavior of HQ drag and diffusion coefficients. The physics of anisotropy is captured in an effective Vlasov term in the transport equation. The effects of the instability are handled by making a relation with the phenomenologically known jet-quenching parameter in RHIC and LHC. Interestingly, the presence of instability significantly affects the temperature and momentum dependences of the HQ drag and diffusion coefficients. These results may have appreciable impact on the experimental observables such as the nuclear suppression factor, $R_{AA}(p_T)$, and the elliptic flow, $v_2(p_T)$, of heavy mesons in heavy ion collisions at RHIC and LHC energies which is a matter of future investigation.

We derive the Landau-Khalatnikov-Frandkin transformation (LKFT) for the fermion propagator in quantum electrodynamics (QED) described within a brane-world inspired framework where photons are allowed to move in $d_{\gamma }$ space-time (bulk) dimensions, while electrons remain confined to a $d_e$-dimensional brane, with $d_e<d_{\gamma }$, referred to in the literature as reduced quantum electrodynamics, ${\mathrm{RQED}}_{d_{\gamma },d_e}$. Specializing to the case of graphene, namely, ${\mathrm{RQED}}_{4,3}$ with massless fermions, we derive the nonperturbative form of the fermion propagator starting from its bare counterpart and then compare its weak coupling expansion to known one- and two-loop perturbative results. The agreement of the gauge-dependent terms at order $\alpha$ and ${\alpha }^2$ is reminiscent of the structure of LKFT in ordinary QED in arbitrary space-time dimensions and provides strong constraints for the multiplicative renormalizability of ${\mathrm{RQED}}_{d_{\gamma },d_e}$.

In this paper we set a framework in which experiments whose goal is to test QED predictions can be used in a more general way to test nonlinear electrodynamics (NLED) which contains low-energy QED as a special case. We review some of these experiments and we establish limits on the different free parameters by generalizing QED predictions in the framework of NLED. We finally discuss the implications of these limits on bound systems and isolated charged particles for which QED has been widely and successfully tested.

We discuss fermions in a spontaneously generated holographic lattice background. The lattice structure at the boundary is generated by introducing a higher-derivative interaction term between a $U(1)$ gauge field and a scalar field. We solve the equations of motion below the critical temperature at which the lattice forms and analyze the change in the Fermi surface due to the lattice. The fermion band structure is found to exhibit a gap due to lattice effects.