In a broad class of consistent models, MeV to few-GeV dark matter interacts with ordinary matter through weakly coupled GeV scale mediators. We show that a suitable meter scale (or smaller) detector situated downstream of an electron beam dump can sensitively probe dark matter interacting via sub-GeV mediators, while B-factory searches cover the 1–5 GeV range. Combined, such experiments explore a well-motivated and otherwise inaccessible region of dark matter parameter space with sensitivity several orders of magnitude beyond existing direct detection constraints. These experiments would also probe invisibly decaying new gauge bosons (“dark photons”) down to kinetic mixing of $ϵ\sim {10}^{-4}$, including the range of parameters relevant for explaining the $(g-2{)}_{\mu }$ discrepancy. Sensitivity to other long-lived dark sector states and to new millicharge particles would also be improved.

Charmless three-body decays of $B$ mesons are studied using a simple model based on the framework of the factorization approach. Hadronic three-body decays receive both resonant and nonresonant contributions. Dominant nonresonant contributions to tree-dominated three-body decays arise from the $b\to u$ tree transition which can be evaluated using heavy-meson chiral perturbation theory valid in the soft-meson limit. For penguin-dominated decays, nonresonant signals come mainly from the penguin amplitude governed by the matrix elements of scalar densities $⟨M_1{M}_2|{\overline{q}}_1{q}_2|0⟩$. We use the measurements of ${\overline{B}}^0\to K_S{K}_S{K}_S$ to constrain the nonresonant component of $⟨K\overline{K}|\overline{s}s|0⟩$. The intermediate vector-meson contributions to three-body decays are identified through the vector current, while the scalar-meson resonances are mainly associated with the scalar density. While the calculated direct $CP$ violation in $B^{-}\to K^{+}{K}^{-}{K}^{-}$ and $B^{-}\to {\pi }^{+}{\pi }^{-}{\pi }^{-}$ decays agrees well with experiment in both magnitude and sign, the predicted $CP$ asymmetries in $B^{-}\to {\pi }^{-}{K}^{+}{K}^{-}$ and $B^{-}\to K^{-}{\pi }^{+}{\pi }^{-}$ have incorrect signs when confronted with experiment. It has been conjectured recently that a possible resolution to this $CP$ puzzle may rely on final-state rescattering of ${\pi }^{+}{\pi }^{-}$ and $K^{+}{K}^{-}$. Assuming a large strong phase associated with the matrix element $⟨K\pi |\overline{s}q|0⟩$ arising from some sort of power corrections, we fit it to the data of $K^{-}{\pi }^{+}{\pi }^{-}$ and find a correct sign for ${\pi }^{-}{K}^{+}{K}^{-}$. We predict some testable $CP$ violation in ${\overline{B}}^0\to K^{+}{K}^{-}{\pi }^0$ and $K^{+}{K}^{-}{K}_S$. In the low-mass regions of the Dalitz plot, we find that the regional $CP$ violation is indeed largely enhanced with respect to the inclusive one, though it is still significantly below the data. In this work, strong phases arise from effective Wilson coefficients, propagators of resonances, and the matrix element of the scalar density $⟨M_1{M}_2|{\overline{q}}_1{q}_2|0⟩$.

We show that the magnitude of the order parameters in the Polyakov–Nambu–Jona-Lasinio (PNJL) model given by the quark condensate and the Polyakov loop can be used as a criterion to clearly identify, without ambiguities, phases and boundaries of the strongly interacting matter, namely, the broken/restored chiral symmetry and confinement/deconfinement regions. This structure is represented by the projection of the order parameters in the temperature-chemical potential plane, which allows a clear identification of pattern changes in the phase diagram. Such a criterion also enables the emergence of a quarkyonic phase even in the two-flavor system. We still show that this new phase diminishes due to the influence of an additional vector-type interaction in the PNJL phase diagrams and is quite sensitive to the effect of the change of the $T_0$ parameter in the Polyakov potential. Finally, we show that the phases and boundaries constructed by our method indicate that the order parameters should be more strongly correlated, as in the case of the entanglement PNJL model. This result suggests a novel way to pursue further investigation of new interactions between the order parameters in order to improve the PNJL model.

We examine the QCD evolution for the transverse momentum dependent observables in hard processes of semi-inclusive hadron production in deep inelastic scattering and Drell-Yan lepton pair production in $pp$ collisions, including the spin-average cross sections and Sivers single transverse spin asymmetries. We show that the evolution equations derived by a direct integral of the Collins-Soper-Sterman evolution kernel from low to high $Q$ can describe well the transverse momentum distributions of the unpolarized cross sections in the $Q^2$ range from 2 to $100{\mathrm{GeV}}^2$. In addition, the matching is established between our evolution and the Collins-Soper-Sterman resummation with $b_{*}$ prescription and Konychev-Nodalsky parametrization of the nonperturbative form factors, which are formulated to describe the Drell-Yan lepton pair and $W/Z$ boson production in hadronic collisions. With these results, we present the predictions for the Sivers single transverse spin asymmetries in Drell-Yan lepton pair production and $W^{\pm }$ boson production in polarized $pp$ and ${\pi }^{-}p$ collisions for several proposed experiments. We emphasize that these experiments will not only provide crucial test of the sign change of the Sivers asymmetry but also provide important opportunities to study the QCD evolution effects.

We perform a coupled-channel study of the possible deuteron-like molecules with two heavy flavor quarks, including the systems of $D^{(*)}{D}^{(*)}$ with double charm, ${\overline{B}}^{(*)}{\overline{B}}^{(*)}$ with double bottom, and $D^{(*)}{\overline{B}}^{(*)}$ with both charm and bottom, within the one-boson-exchange potential model. In our study, we take into account the $S\mathrm{\text{−}}D$ mixing which plays an important role in the formation of the loosely bound deuteron, and particularly, the coupled-channel effect in the flavor space. According to our results, the state $D^{(*)}{D}^{(*)}[I(J^P)=0(1^{+})]$ with double charm, the states ${\overline{B}}^{(*)}{\overline{B}}^{(*)}[I(J^P)=0(1^{+}),1(1^{+})]$, $({\overline{B}}^{(*)}{\overline{B}}^{(*)}{)}_s[J^P=1^{+},2^{+}]$ and $({\overline{B}}^{(*)}{\overline{B}}^{(*)}{)}_{ss}[J^P=1^{+},2^{+}]$ with double bottom, and the states $D^{(*)}{\overline{B}}^{(*)}[I(J^P)=0(1^{+}),0(2^{+})]$ with both charm and bottom might be good molecule candidates. However, the states $D^{(*)}{D}^{(*)}[I(J^P)=0(2^{+}),1(0^{+}),1(1^{+}),1(2^{+})]$, $(D^{(*)}{D}^{(*)}{)}_s[J^P=0^{+},2^{+}]$ and $(D^{(*)}{D}^{(*)}{)}_{ss}[J^P=0^{+},1^{+},2^{+}]$ with double charm and the state $D^{(*)}{\overline{B}}^{(*)}[I(J^P)=1(1^{+})]$ with both charm and bottom are not supported to be molecules.

In this paper we use an eikonalized minijet model where the effects of the first nonlinear corrections to the DGLAP equations are taken into account. The contributions coming from gluon recombination effects are included in the $\mathrm{DGLAP}+\mathrm{GLRMQ}$ approach for the free proton in the context of saturation models. The parameters of the model are fixed to fit total $pp$ and $\overline{p}p$ cross sections, including the very recent data from LHC, HiRes, and Pierre Auger collaborations. Glauber and multiple scattering approximations are then used to describe the inclusive inelastic proton-Air cross section. Photoproduction cross sections, without change of parameters fixed before, are also obtained from the model using vector meson dominance and the additive quark model. We show and discuss our main results as well as the implications of saturation effects in the behavior of total hadronic and photonic cross sections at very high energies.

We study the collider signature of pseudo-Dirac heavy neutrinos in the inverse seesaw scenario, where the heavy neutrinos with mass at the electroweak scale can have sizable mixings with the Standard Model neutrinos, while providing the tiny light neutrino masses by the inverse seesaw mechanism. Based on a simple, concrete model realizing the inverse seesaw scenario, we fix the model parameters so as to reproduce the neutrino oscillation data and to satisfy other experimental constraints, assuming two typical flavor structures of the model and the different types of hierarchical light neutrino mass spectra. For completeness, we also consider a general parametrization for the model parameters by introducing an arbitrary orthogonal matrix and the nonzero Dirac and Majorana phases. We perform a parameter scan to identify an allowed parameter region which satisfies all experimental constraints. With the fixed parameters, we analyze the heavy neutrino signal at the LHC through trilepton final states with large missing energy and at the ILC through a single lepton plus dijet with large missing energy. We find that in some cases, the heavy neutrino signal can be observed with a large statistical significance via different flavor charged lepton final states.

We search for ultra-high energy photons by analyzing geometrical properties of shower fronts of events registered by the Telescope Array surface detector. By making use of an event-by-event statistical method, we derive upper limits on the absolute flux of primary photons with energies above ${10}^{19}$, ${10}^{19.5}$, and ${10}^{20}\mathrm{eV}$ based on the first three years of data taken.

The hidden sector photon is a weakly interacting hypothetical particle with sub-eV mass that kinetically mixes with the photon. We describe a microwave frequency light shining through a wall experiment, where a cryogenic resonant microwave cavity is used to try and detect photons that have passed through an impenetrable barrier, a process only possible via mixing with hidden sector photons. For a hidden sector photon mass of $53\mu \mathrm{eV}$, we limit the hidden photon kinetic mixing parameter $\chi <1.7\times {10}^{-7}$, which is an order of magnitude lower than previous bounds derived from cavity experiments in the same mass range. In addition, we use the cryogenic detector cavity to place new limits on the kinetic mixing parameter for hidden sector photons as a form of cold dark matter.

An updated search is performed for gluino, top squark, or bottom squark $R$-hadrons that have come to rest within the ATLAS calorimeter, and decay at some later time to hadronic jets and a neutralino, using 5.0 and $22.9{\mathrm{fb}}^{-1}$ of $pp$ collisions at 7 and 8 TeV, respectively. Candidate decay events are triggered in selected empty bunch crossings of the LHC in order to remove $pp$ collision backgrounds. Selections based on jet shape and muon system activity are applied to discriminate signal events from cosmic ray and beam-halo muon backgrounds. In the absence of an excess of events, improved limits are set on gluino, stop, and sbottom masses for different decays, lifetimes, and neutralino masses. With a neutralino of mass 100 GeV, the analysis excludes gluinos with mass below 832 GeV (with an expected lower limit of 731 GeV), for a gluino lifetime between $10\mu \mathrm{s}$ and 1000 s in the generic $R$-hadron model with equal branching ratios for decays to $q\overline{q}{\tilde{\chi }}^0$ and $g{\tilde{\chi }}^0$. Under the same assumptions for the neutralino mass and squark lifetime, top squarks and bottom squarks in the Regge $R$-hadron model are excluded with masses below 379 and 344 GeV, respectively.

Using a sample of $1.06\times {10}^8\psi (3686)$ events collected with the BESIII detector at BEPCII, the decays ${\eta }_c(2S)\to p\overline{p}$ and $h_c\to p\overline{p}$ are searched for, where ${\eta }_c(2S)$ and $h_c$ are reconstructed in the decay chains $\psi (3686)\to \gamma {\eta }_c(2S)$, ${\eta }_c(2S)\to p\overline{p}$ and $\psi (3686)\to {\pi }^0{h}_c$, $h_c\to p\overline{p}$, respectively. No significant signals are observed. The upper limits of the product branching fractions are determined to be $\mathcal{B}(\psi (3686)\to \gamma {\eta }_c(2S))\times \mathcal{B}({\eta }_c(2S)\to p\overline{p})<1.4\times {10}^{-6}$ and $\mathcal{B}(\psi (3686)\to {\pi }^0{h}_c)\times \mathcal{B}(h_c\to p\overline{p})<1.3\times {10}^{-7}$ at the 90% C.L.. The branching fractions for ${\chi }_{cJ}\to p\overline{p}$ ($J=0$, 1, 2) are also measured to be $(24.5\pm 0.8\pm 1.3,8.6\pm 0.5\pm 0.5,8.4\pm 0.5\pm 0.5)\times {10}^{-5}$, which are the world’s most precise measurements.

We describe an effective theory of a scalar field, motivated by some features expected in the low energy theory of gluodynamics in $3+1$ dimensions. The theory describes two propagating massless particles in a certain limit, which we identify with the Abelian QED limit, and has classical string solutions in the general case. The string solutions are somewhat unusual as they are multiply degenerate due to the spontaneous breaking of diffeomorphism invariance. Nevertheless, all solutions yield an identical electric field and have the same string tension.

We present nonlinear uplift Ansätze for all the bosonic degrees of freedom and dual fields in the $S^7$ reduction of $D=11$ supergravity to maximal SO(8) gauged supergravity and test them for the $\mathrm{SO}(7{)}^{\pm }$ invariant solutions. In particular, we complete the known Ansätze for the internal components of the metric and four-form flux by constructing a nonlinear Ansatz for the internal components of the dual seven-form flux. Furthermore, we provide Ansätze for the complete set of 56 vector fields, which are given by more general structures than those available from standard Kaluza-Klein theory. The novel features encountered here have no conventional geometric interpretation and provide a new perspective on Kaluza-Klein theory. We study the recently found set of generalized vielbein postulates and, for the $S^7$ compactification, we show that they reduce to the ${\mathrm{E}}_{7(7)}$ Cartan equation of maximal SO(8) gauged supergravity in four dimensions. The significance of this framework for a higher-dimensional understanding of the embedding tensor and other gauged maximal supergravities is briefly discussed.

We compute the Yang-Mills vacuum wave functional in three dimensions at weak coupling with $\mathcal{O}(e^2)$ precision. We use two different methods to solve the functional Schrödinger equation. One of them generalizes to $\mathcal{O}(e^2)$ the method followed by Hatfield at $\mathcal{O}(e)$ [Phys. Lett. B 147, 435 (1984)]. The other uses the weak coupling version of the gauge invariant formulation of the Schrödinger equation and the ground state wave functional followed by Karabali, Nair, and Yelnikov [Nucl. Phys. B824, 387 (2010)]. We compare both results and discuss the differences between them.

In this paper, we have considered a closed string tachyon model with a constant dilaton field and interacted it with Chaplygin gas for evaluating cosmology parameters. The model has been studied in 26 dimensions, with 22 dimensions related to compactification on an internal nonflat space and its other 4 dimensions related to the Friedmann-Lemaître-Robertson-Walker metric. By taking the internal curvature as a negative constant, we reconstructed the closed string tachyon potential in terms of tachyon field as a quartic equation. The tachyon field and the scale factor have been achieved as a function of time evolution and geometry of curved space where the behavior of the scale factor describes an accelerated expansion of the Universe. Next, we discussed the stability of our model by introducing a sound speed factor, which must be, in our case, a positive function. By drawing sound speed against time evolution, we investigated stability conditions for a nonflat universe in its three stages: early, late, and future time. As a result we shall see that in these cases there remains an instability at early time and a stability point at late time.

A corotating bosonic field interacting with a spinning Kerr black hole can extract rotational energy and angular momentum from the hole. This intriguing phenomenon is known as superradiant scattering. As pointed out by Press and Teukolsky, the black-hole-field system can be made unstable (explosive) by placing a reflecting mirror around the black hole, which prevents the extracted energy from escaping to infinity. This composed black-hole-mirror-field bomb has been studied extensively by many researchers. It is worth noting, however, that most former studies of the black-hole bomb phenomenon have focused on the specific case of confined scalar (spin-0) fields. In the present study we explore the physical properties of the higher-spin (electromagnetic and gravitational) black-hole bombs. It is shown that this composed system is amenable to an analytic treatment in the physically interesting regime of rapidly rotating black holes. In particular, we prove that the composed black-hole-mirror-field bomb is characterized by the unstable resonance frequency $\omega =m{\Omega }_{\mathrm{H}}+is·2\pi T_{\mathrm{BH}}$ (here $s$ and $m$ are, respectively, the spin parameter and the azimuthal harmonic index of the field, and ${\Omega }_{\mathrm{H}}$ and $T_{\mathrm{BH}}$ are, respectively, the angular-velocity and the temperature of the rapidly spinning black hole). Our results provide evidence that the higher-spin (electromagnetic and gravitational) black-hole-mirror bombs are much more explosive than the extensively studied scalar black-hole-mirror bomb. In particular, it is shown here that the instability growth rates that characterize the higher-spin black-hole bombs are 2 orders of magnitude larger than the instability growth rate of the scalar black-hole bomb.

Recently the first example of a unitary theory of Lorentz-invariant massive gravity allowing for stable self-accelerating de Sitter solutions was found, extending the quasidilaton theory. In this paper we further generalize this new action for the quasidilaton field by introducing general Lagrangian terms which are consistent with the quasidilaton symmetry while leading to second order equations of motion. We find that the structure of the theory, compared to the simplest stable example, does not change on introducing these new terms.

We discuss the quantization of an unstable field through the construction of a “one-particle Hilbert space.” The system considered here is a neutral scalar field evolving over a globally hyperbolic static spacetime and subject to a stationary external scalar potential. In order to prove our results we assume spacetimes without horizons and that the theory possess a “mass gap.” Our strategy consists in building a complex structure, which arises from a suitable positive bilinear form defined over the space of classical solutions of the field equation. Once the space of states of the quantum field has been set, it is possible to study the effect of the time translation symmetry on it. From the time translation operator we obtain an expression for the Hamiltonian operator associated with the unstable sector of the field. This last result coincides with findings from long ago showing that the unstable degrees of freedom of the field behave as nonrelativistic particles in a parabolic potential barrier.

Inspired by recent results of unusual properties of loop processes in relative locality, we introduce a way to classify loops in the case of $\kappa$-Poincaré momentum space. We show that the notion of orientability is deeply connected to a few essential properties of loop processes. Nonorientable loops have effective curvature, which explicitly breaks translation symmetry, and can lead to a breaking of causality and global momentum conservation. Orientable loops, on the other hand, are “flat.” Causality and global momentum conservation are all well preserved in these kinds of loops. We comment that the nontrivial classical loops in relative locality might be understood as dual effects from general relativity, and some physical implications are discussed.

The particle acceleration mechanism in $S^2\times {\mathbb{R}}^1$ topology, namely, in the spacetime of the five-dimensional compact black string, has been studied. The expression of center-of-mass energy of the colliding neutral particles near static black string has been found. The collision of a charged particle moving at the innermost stable circular orbit with a neutral particle coming from infinity has been considered when black string is immersed in external uniform magnetic field. It has been shown that the unlimited center-of-mass energy can be approached in the case of the extremal rotation of the black string which is similar to the analogous effect in Kerr spacetime. We have also obtained that the scattering energy of particles in the center-of-mass system can take arbitrarily large values not only for extremal black string but also for the nonextremal one. It has been derived that the presence of the extra dimension can, in principle, increase the upper limit of efficiency of energy extraction from the extremely rotating black string up to 203% versus 143% which can be extracted from the extreme Kerr black hole.