We study the implications of the recent measurements of $R_K$ and $R_{K^{*}}$ by the LHCb Collaboration. We do that by adopting a model-independent approach based on the Standard Model effective field theory (SMEFT), with the dominant new physics (NP) effects encoded in the coefficients of dimension-6 operators respecting the full Standard Model (SM) gauge symmetry. After providing simplified expressions for $R_K$ and $R_{K^{*}}$, we determine the implications of the recent LHCb results for these observables on the coefficients of the SMEFT operators at low and high energies. We also take into account all $b\to s\ell \ell$ data, which combined lead to effective NP scenarios with SM pulls in excess of $5\sigma$. Thus, the operators discussed in this paper would be the first dimension-6 terms in the SM Lagrangian to be detected experimentally. Indirect constraints on these operators are also discussed. The results of this paper transcend the singularity of the present situation and set a standard for future analyses in $b\to s$ transitions when the NP is assumed to lie above the electroweak scale.

We consider the lepton number violating decays $B\to {\mu }^{\pm }{\mu }^{\pm }{\pi }^{\mp }$ and $B\to D^{(*)}{\mu }^{\pm }{\mu }^{\pm }{\pi }^{\mp }$ which may be detected at the LHCb and Belle-II experiments and $B\to {\mu }^{\pm }{\mu }^{\pm }{e}^{\mp }\nu$ and $B\to D^{(*)}{\mu }^{\pm }{\mu }^{\pm }{e}^{\mp }\nu$ decays which may be detected at the Belle-II experiment. The projected total number of produced $B$ mesons is $4.8\times 10^{12}$ at the LHCb upgrade and $5\times 10^{10}$ at Belle-II. For the case in which the above decays are not detected, we deduce the new upper bounds (sensitivity limits) for the mixing parameter $|U_{\mu N}{|}^2$ of heavy sterile neutrino with sub-eV light neutrino, as a function of the sterile neutrino mass in the interval $1.75\mathrm{GeV}<M_N<5.0\mathrm{GeV}$. We take into account the probability of decay of the sterile neutrino $N$ within the detector, taking as the effective detector length $L=2.3m$ at the LCHb upgrade and $L=1m$ at Belle-II. In the interval $1.75\mathrm{GeV}<M_N<3\mathrm{GeV}$, the most stringent bounds can be obtained with the decays $B\to {\mu }^{\pm }{\mu }^{\pm }{\pi }^{\mp }$ at the LHCb upgrade. The sensitivity limits are expected to be, in general, more stringent at the LHCb upgrade than at Belle-II, principally because the number of produced $B$ mesons in the LHCb upgrade is expected to be about 2 orders of magnitude larger than at Belle-II. We conclude that the LHCb upgrade and Belle-II experiments have the potential to either find a new heavy Majorana neutrino $N$ or to improve significantly the sensitivity limits (upper bounds) on the heavy-light mixing parameter $|U_{\mu N}{|}^2$, particularly in the mass range $1.75\mathrm{GeV}<M_N<3\mathrm{GeV}$. This work is a continuation and refinement of our previous work [Phys. Rev. D 94, 053001 (2016); Phys. Rev. D 95, 039901(E) (2017)] on the subject.

We consider a scenario of a minimal supersymmetric standard model with $R$-parity violation, where the lightest supersymmetric particle is the lighter bottom squark $({\tilde{b}}_1)$. We study the production of a bottom squark pair at the LHC and their subsequent decays through the baryon number violating operators leading to a top pair with two light quarks. Looking for both semileptonic and fully hadronic (no leptons) final states, we perform cut-based as well as multivariate analyses (MVA) to estimate the signal significance at the 13 TeV run of the LHC. We find that a cut-based analysis can probe bottom squark mass up to $\sim 750\mathrm{GeV}$, which may be extended up to $\sim 850\mathrm{GeV}$ using MVA with $300{\mathrm{fb}}^{-1}$ integrated luminosity. The fully hadronic final state, however, is not as promising.

We study chemical-potential dependence of confinement and mass gap in QCD with adjoint fermions in spacetime with one spatial compact direction. By calculating the one-loop effective potential for the Wilson line in the presence of a chemical potential, we show that a center-symmetric phase and a center-broken phase alternate when the chemical potential in units of the compactification scale is increased. In the center-symmetric phase we use semiclassical methods to show that photons in the magnetic bion plasma acquire a mass gap that grows with the chemical potential as a result of anisotropic interactions between monopole-instantons. For the neutral fermionic sector which remains gapless perturbatively, there are two possibilities at a nonperturbative level: either to remain gapless (unbroken global symmetry) or to undergo a novel superfluid transition through a four-fermion interaction (broken global symmetry). If the latter is the case, this leads to an energy gap of quarks proportional to a new nonperturbative scale $L^{-1}\exp [-1/(g^4\mu L)]$, where $L$ denotes the circumference of $S^1$, the low-energy physics is described by a Nambu-Goldstone mode associated with the baryon number, and there exists a new type of BEC-BCS crossover of the diquark pairing as a function of the compactification scale at a small chemical potential.

We address the evolution of heavy-quarkonium states in an expanding quark-gluon plasma by implementing effective field theory techniques in the framework of open quantum systems. In this setting we compute the nuclear modification factors for quarkonia that are $S$-wave Coulombic bound states in a strongly coupled quark-gluon plasma. The calculation is performed at an accuracy that is leading order in the heavy-quark density expansion and next-to-leading order in the multipole expansion. The quarkonium density-matrix evolution equations can be written in the Lindblad form, and, hence, they account for both dissociation and recombination. Thermal mass shifts, thermal widths and the Lindblad equation itself depend on only two nonperturbative parameters: the heavy-quark momentum diffusion coefficient and its dispersive counterpart. Finally, by numerically solving the Lindblad equation, we provide results for the $\mathrm{\Upsilon }(1S)$ and $\mathrm{\Upsilon }(2S)$ suppression.

Isospin splittings in baryons with two heavy quarks and a $u$ or $d$ quark are calculated using simple methods proposed previously by the authors. The results are $M({\mathrm{\Xi }}_{cc}^{++})-M({\mathrm{\Xi }}_{cc}^{+})=1.41\pm 0.12^{+0.76}\mathrm{MeV}$, $M({\mathrm{\Xi }}_{bb}^0)-M({\mathrm{\Xi }}_{bb}^{-})=-4.78\pm 0.06^{+0.03}\mathrm{MeV}$, and $M({\mathrm{\Xi }}_{bc}^{+})-M({\mathrm{\Xi }}_{bc}^0)=-1.69\pm 0.07^{+0.39}\mathrm{MeV}$, where the statistical errors reflect uncertainties in input mass splittings, and the systematic errors are associated with the choice of constituent-quark masses.

Long-baseline neutrino oscillation experiments, in particular the Deep Underground Neutrino Experiment (DUNE) and Tokai to Hyper-Kamiokande (T2HK), will lead the effort in the precision determination of the as yet unknown parameters of the leptonic mixing matrix. In this article, we revisit the potential of DUNE, T2HK and their combination in light of the most recent experimental information. As well as addressing more conventional questions, we pay particular attention to the attainable precision on $\delta$, which is playing an increasingly important role in the physics case of the long-baseline program. We analyze the complementarity of the two designs, identify the benefit of a program comprising distinct experiments and consider how best to optimize the global oscillation program. This latter question is particularly pertinent in light of a number of alternative design options which have recently been mooted: a Korean second detector for T2HK and different beams options at DUNE. We study the impact of these options and quantify the synergies between alternative proposals, identifying the best means of furthering our knowledge of the fundamental physics of neutrino oscillation.

A search for supersymmetry is presented based on multijet events with large missing transverse momentum produced in proton-proton collisions at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$. The data, corresponding to an integrated luminosity of $35.9{\mathrm{fb}}^{-1}$, were collected with the CMS detector at the CERN LHC in 2016. The analysis utilizes four-dimensional exclusive search regions defined in terms of the number of jets, the number of tagged bottom quark jets, the scalar sum of jet transverse momenta, and the magnitude of the vector sum of jet transverse momenta. No evidence for a significant excess of events is observed relative to the expectation from the standard model. Limits on the cross sections for the pair production of gluinos and squarks are derived in the context of simplified models. Assuming the lightest supersymmetric particle to be a weakly interacting neutralino, 95% confidence level lower limits on the gluino mass as large as 1800 to 1960 GeV are derived, and on the squark mass as large as 960 to 1390 GeV, depending on the production and decay scenario.

We propose a new scenario for predicting a one-loop neutron-antineutron oscillation at a testable level, meanwhile, realizing a thermal or inflationary baryogenesis at a very high scale. Besides the standard model content, this scenario involves two real singlet scalars with very heavy masses, two color-triplet and isosinglet scalars at the TeV scale, as well as a Majorana singlet fermion for a dark matter candidate.

We present a new type IIB supergravity background of the warped form ${\mathrm{AdS}}_4\times {\mathcal{M}}_6$ with dilaton, $B$-field and all Ramond-Ramond fluxes turned on. We obtain the solution by applying non-Abelian T-duality to a certain representative of a class of ${\mathrm{AdS}}_4$ backgrounds in massive IIA supergravity. By explicitly constructing the Killing spinor of the seed solution and using an argument involving Kosmann spinorial Lie derivative we demonstrate that the background is supersymmetric.

We provide a complete classification of all abelian gauge invariant $p$-form theories with equations of motion depending only on the second derivative of the field—the $p$-form analogues of the Galileon scalar field theory. We construct explicitly the nontrivial actions that exist for spacetime dimension $D\le 11$, but our methods are general enough and can be extended to arbitrary $D$. We uncover in particular a new 4-form Galileon cubic theory in $D\ge 8$ dimensions. As a by-product we give a simple proof of the fact that the equations of motion depend on the $p$-form gauge fields only through their field strengths and show this explicitly for the recently discovered 3-form Galileon quartic theory.

Modified gravity theories are supposed to incorporate low-energy quantum-gravity effects and, at the same time, they could shed light into the dark matter and dark energy problems. Here we study a particular modification of general relativity where local Lorentz invariance is spontaneously broken and whose physical effects, despite a decade-long effort, were unknown. We show that, during inflation, this modification produces anisotropies that would generate measurable effects on the cosmic microwave background. Then, by using empirical constraints on the B-mode polarization spectrum, we can estimate that the “coefficient” components absolute value have to be smaller than ${10}^{-43}$. This is a remarkably strong limit; in fact, it is 29 orders of magnitude better than the best constraints on similar coefficients. Thus, we propose that inflation could stringently test other modified gravity theories.

The Ostrogradski ghost problem that appears in a higher-derivative system is considered for theories with constraints. A new prescription for removal of the ghost-creating momenta that come along the constrained systems is described based on the Dirac’s constraint analysis. It is shown how one can make the canonical Hamiltonian bounded from below by systematically removing the constraints appearing in the system, thereby reducing the effective dimension of the phase space. To show the effect of higher-derivative terms, we consider the singularity-free Gauss-Bonnet theory coupled via a matter field to the Einstein-Hilbert action. Finally, we construct the canonical Hamiltonian for the theory that is bounded from below.

The characteristic damping times of the natural oscillations of a Kerr black hole become arbitrarily large as the extremal limit is approached. This behavior is associated with the so-called zero damped modes (ZDMs), and suggests that extremal black holes are characterized by quasinormal modes whose frequencies are purely real. Since these frequencies correspond to oscillations whose angular phase velocity matches the horizon angular velocity of the black hole, they are sometimes called “synchronous frequencies.” Several authors have studied the ZDMs for near-extremal black holes. Recently, their correspondence to branch points of the Green’s function of the wave equation was linked to the Aretakis instability of extremal black holes. Here we investigate the existence of ZDMs for extremal black holes, showing that these real-axis resonances of the field are unphysical as natural black hole oscillations: the corresponding frequency is always associated with a scattering mode. By analyzing the behavior of these modes near the event horizon we obtain new insight into the transition to extremality, including a simple way to understand the Aretakis instability.

We consider higher derivative supergravities that are dual to ghost-free $N=1$ supergravity theories in the Einstein frame. The duality is implemented by deforming the Kähler function, and/or the superpotential, to include nonlinear dependences on chiral fields that, in other approaches, play the role of the Lagrange multipliers employed to establish this duality. These models are of the no-scale type, and in the minimal case, they require the presence of four chiral multiplets, with a Kähler potential having the structure of the $SU(4,1)/SU(4)\times U(1)$ coset manifold. In the standard $N=1$ supergravity formulation, these models are described by a multifield scalar potential, featuring Starobinsky-like behavior in particular directions.

We study the Hamiltonian dynamics of the dust-Bianchi IX universe in dust time gauge. This model has three physical metric degrees of freedom, with evolution determined by a time-independent physical Hamiltonian. This approach gives a new physical picture where dust-Bianchi IX dynamics is described by oscillations between dust-Kasner solutions, rather than between vacuum-Kasner solutions. We derive a generalized transition law between these phases, which has a matter component. Sufficiently close to a singularity, we show that this law reduces to the vacuum Belinski-Khalatnikov-Lifshitz map. We include an analysis with dust and a scalar field. Lastly, we describe a path integral quantization using the dust-time physical Hamiltonian and derive an effective action for the dust-Kasner model by integrating out the anisotropy degrees of freedom.

The recent birth of gravitational wave astronomy invites a new generation of precision tests of general relativity. Signatures of black hole (BH) mergers must be systematically explored in a wide spectrum of modified gravity theories. Here, we turn to one such theory in which the initial value problem for BH mergers is well posed, the Einstein-Maxwell-dilaton system. We present conservative estimates for the merger parameters (final spins, quasinormal modes) based on techniques that have worked well for ordinary gravity mergers and utilize information extracted from test particle motion in the final BH metric. The computation is developed in parallel for the modified gravity BHs (we specifically focus on the Kaluza-Klein value of the dilaton coupling, for which analytic BH solutions are known) and ordinary Kerr-Newman BHs. We comment on the possibility of obtaining final BHs with spins consistent with current observations.

We derive spherically symmetric solutions of the classical $\lambda \text{−}R$ model, a minimal, anisotropic modification of general relativity with a preferred foliation and two local degrees of freedom. Starting from a $3+1$ decomposition of the four-metric in a general spherically symmetric ansatz, we perform a phase space analysis of the reduced model. We show that its constraint algebra is consistent with that of the full $\lambda \text{−}R$ model, and also yields a constant mean curvature or maximal slicing condition as a tertiary constraint. Although the solutions contain the standard Schwarzschild geometry for the general relativistic value $\lambda =1$ or for vanishing mean extrinsic curvature $K$, they are in general nonstatic, incompatible with asymptotic flatness, and parametrized not only by a conserved mass. We show by explicit computation that the four-dimensional Ricci scalar of the solutions is in general time dependent and nonvanishing.

We study the effects of collective neutrino oscillations on $\nu p$ process nucleosynthesis in proton-rich neutrino-driven winds by including both the multiangle $3\times 3$ flavor mixing and the nucleosynthesis network calculation. The number flux of energetic electron antineutrinos is raised by collective neutrino oscillations in a 1D supernova model for the $40M_{\odot }$ progenitor. When the gas temperature decreases down to $\sim 2–3\times {10}^9\mathrm{K}$, the increased flux of electron antineutrinos promotes the $\nu p$ process more actively, resulting in the enhancement of $p$-nuclei. In the early phase of neutrino-driven wind, blowing at 0.6 s after core bounce, oscillation effects are prominent in inverted mass hierarchy and $p$-nuclei are synthesized up to ${}^{106}\mathrm{Cd}$ and ${}^{108}\mathrm{Cd}$. On the other hand, in the later wind trajectory at 1.1 s after core bounce, abundances of $p$-nuclei are increased remarkably by $\sim 10–{10}^4$ times in normal mass hierarchy and even reaching heavier $p$-nuclei such as ${}^{124}\mathrm{Xe}$, ${}^{126}\mathrm{Xe}$ and ${}^{130}\mathrm{Ba}$. The averaged overproduction factor of $p$-nuclei is dominated by the later wind trajectories. Our results demonstrate that collective neutrino oscillations can strongly influence the $\nu p$ process, which indicates that they should be included in the network calculations in order to obtain precise abundances of $p$-nuclei. The conclusions of this paper depend on the difference of initial neutrino parameters between electron and nonelectron antineutrino flavors which is large in our case. Further systematic studies on input neutrino physics and wind trajectories are necessary to draw a robust conclusion. However, this finding would help understand the origin of solar-system isotopic abundances of $p$-nuclei such as ${}^{92,94}\mathrm{Mo}$ and ${}^{96,98}\mathrm{Ru}$.

An important source of background in direct searches for low-mass dark matter particles are the energy deposits by small-angle scattering of environmental $\gamma$ rays. We report detailed measurements of low-energy spectra from Compton scattering of $\gamma$ rays in the bulk silicon of a charge-coupled device (CCD). Electron recoils produced by $\gamma$ rays from ${}^{57}\mathrm{Co}$ and ${}^{241}\mathrm{Am}$ radioactive sources are measured between 60 eV and 4 keV. The observed spectra agree qualitatively with theoretical predictions, and characteristic spectral features associated with the atomic structure of the silicon target are accurately measured for the first time. A theoretically motivated parametrization of the data that describes the Compton spectrum at low energies for any incident $\gamma$-ray flux is derived. The result is directly applicable to background estimations for low-mass dark matter direct-detection experiments based on silicon detectors, in particular for the DAMIC experiment down to its current energy threshold.