Anomalous $b\to s$ transitions from LHCb data may suggest a new massive gauge boson $Z^{\prime }$ that couples to the left-handed $b\to s$ current, which in turn implies a coupling to the $t\to c$ current. In this paper, we study flavor-changing neutral current (FCNC) decays of the top quark induced by a $Z^{\prime }$ boson, namely $t\to c{Z}^{\prime }$, based on a model of the gauged $L_{\mu }-L_{\tau }$ symmetry (the difference between the muon and tauon numbers) with vectorlike quarks, which was introduced to explain the anomalous LHCb data. We illustrate that searching for $t\to c{Z}^{\prime }$ via $Z^{\prime }\to {\mu }^{+}{\mu }^{-}$ with LHC Run 1 data can probe a parameter region that is unexplored by $B$ physics for a $Z^{\prime }$ mass of around $\mathcal{O}(10)\mathrm{GeV}$ or greater. We further extend the model to a very light $Z^{\prime }$ with mass below 400 MeV, which is motivated by the muon $g-2$ anomaly. Taking rare $B$ and $K$ meson decay data into account, we give upper limits on the $t\to c{Z}^{\prime }$ branching ratio for the light $Z^{\prime }$ case, and discuss about its observability at the LHC. We also scrutinize the possibility that the decay $K_L\to {\pi }^0{Z}^{\prime }$ with $Z^{\prime }\to \nu \overline{\nu }$ may lead to an apparent violation of the usual Grossman-Nir bound of $\mathcal{B}(K_L\to {\pi }^0\nu \overline{\nu })<1.4\times {10}^{-9}$.

We consider the real topological string on certain noncompact toric Calabi-Yau three-folds $\mathbb{X}$, in its physical realization describing an orientifold of type IIA on $\mathbb{X}$ with an O4-plane and a single D4-brane stuck on top. The orientifold can be regarded as a new kind of surface operator on the gauge theory with 8 supercharges arising from the singular geometry. We use the M-theory lift of this system to compute the real Gopakumar-Vafa invariants (describing wrapped M2-brane Bogomol’nyi-Prasad-Sommerfield (BPS) states) for diverse geometries. We show that the real topological string amplitudes pick up certain signs across flop transitions, in a well-defined pattern consistent with continuity of the real BPS invariants. We further give some preliminary proposals of an intrinsically gauge theoretical description of the effect of the surface operator in the gauge theory partition function.

The path-integral quantization method is applied to a relativistically covariant version of the Hopfield model, which represents a very interesting mesoscopic framework for the description of the interaction between quantum light and dielectric quantum matter, with particular reference to the context of analogue gravity. In order to take into account the constraints occurring in the model, we adopt the Faddeev-Jackiw approach to constrained quantization in the path-integral formalism. In particular, we demonstrate that the propagator obtained with the Faddeev-Jackiw approach is equivalent to the one which, in the framework of Dirac canonical quantization for constrained systems, can be directly computed as the vacuum expectation value of the time-ordered product of the fields. Our analysis also provides an explicit example of quantization of the electromagnetic field in a covariant gauge and coupled with the polarization field, which is a novel contribution to the literature on the Faddeev-Jackiw procedure.

The Senovilla family for a subclass of Petrov type-D stationary axisymmetric differentially rotating perfect fluids is considered. A scheme is presented to construct from a solution an interior of a rotating compact body satisfying dominant energy conditions and with a boundary of vanishing pressure. The equatorial disk of the body is a surface layer due to a jump in the second fundamental form. However, unlike previous results, the body is free from curvature singularities.

Inspiraling compact binaries with non-negligible orbital eccentricities are plausible gravitational wave (GW) sources for the upcoming network of GW observatories. In this paper, we present two prescriptions to compute post-Newtonian (PN) accurate inspiral templates for such binaries. First, we adapt and extend the postcircular scheme of Yunes et al. [Phys. Rev. D 80, 084001 (2009)] to obtain a Fourier-domain inspiral approximant that incorporates the effects of PN-accurate orbital eccentricity evolution. This results in a fully analytic frequency-domain inspiral waveform with Newtonian amplitude and 2PN-order Fourier phase while incorporating eccentricity effects up to sixth order at each PN order. The importance of incorporating eccentricity evolution contributions to the Fourier phase in a PN-consistent manner is also demonstrated. Second, we present an accurate and efficient prescription to incorporate orbital eccentricity into the quasicircular time-domain TaylorT4 approximant at 2PN order. New features include the use of rational functions in orbital eccentricity to implement the 1.5PN-order tail contributions to the far-zone fluxes. This leads to closed form PN-accurate differential equations for evolving eccentric orbits, and the resulting time-domain approximant is accurate and efficient to handle initial orbital eccentricities $\le 0.9$. Preliminary GW data analysis implications are probed using match estimates.

Einstein equations projected on to a black-hole horizon give rise to Navier-Stokes equations. Horizon-fluids typically possess unusual features like negative bulk viscosity, and it is not clear whether a statistical-mechanical description exists for such fluids. In this work, we provide an explicit derivation of the Bulk viscosity of the horizon-fluid based on the theory of fluctuations à la Kubo. The main advantage of our approach is that our analysis remains for the most part independent of the details of the underlying microscopic theory and hence the conclusions reached here are model independent. We show that the coefficient of bulk viscosity for the horizon-fluid matches exactly with the value found from the equations of motion for the horizon-fluid.

The theories known as doubly special relativity are introduced in order to take into account an observer-independent length scale and the speed of light in the framework of special relativity. These theories can be generally formulated on the de Sitter and also recently proposed anti-de Sitter momentum spaces. In the context of these theories, we study the statistical mechanics, and to do this, we consider the natural measure on the corresponding extended phase space. The invariant measure on the space of distinct microstates is obtained by restriction of the natural measure of the extended phase space to the physical phase space through the disintegration theorem. Having the invariant measure, one can study the statistical mechanics in an arbitrary ensemble for any doubly special relativity theory. We use the constructed setup to study the statistical properties of four doubly special relativity models. Applying the results to the case of early universe thermodynamics, we show that one of these models that is defined by the cosmological coordinatization of anti-de Sitter momentum space implies a finite total number of microstates. Therefore, without attribution to any ensemble density, and quite generally, we obtain entropy and internal energy bounds for the early radiation dominated universe. We find that while these results cannot be supported by the standard Friedmann equations, they indeed are in complete agreement with the nonsingular effective Friedmann equations that arise in the context of loop quantum cosmology.

We model the inspiral of a compact stellar-mass object into a massive nonrotating black hole including all dissipative and conservative first-order-in-the-mass-ratio effects on the orbital motion. The techniques we develop allow inspirals with initial eccentricities as high as $e\sim 0.8$ and initial separations as large as $p\sim 50$ to be evolved through many thousands of orbits up to the onset of the plunge into the black hole. The inspiral is computed using an osculating elements scheme driven by a hybridized self-force model, which combines Lorenz-gauge self-force results with highly accurate flux data from a Regge-Wheeler-Zerilli code. The high accuracy of our hybrid self-force model allows the orbital phase of the inspirals to be tracked to within $\sim 0.1$ radians or better. The difference between self-force models and inspirals computed in the radiative approximation is quantified.

We analytically compute, through the six-and-a-half post-Newtonian order, the second-order-in-eccentricity piece of the Detweiler-Barack-Sago gauge-invariant redshift function for a small mass in eccentric orbit around a Schwarzschild black hole. Using the first law of mechanics for eccentric orbits [A. Le Tiec, First law of mechanics for compact binaries on eccentric orbits, Phys. Rev. D 92, 084021 (2015).] we transcribe our result into a correspondingly accurate knowledge of the second radial potential of the effective-one-body formalism [A. Buonanno and T. Damour, Effective one-body approach to general relativistic two-body dynamics, Phys. Rev. D 59, 084006 (1999).]. We compare our newly acquired analytical information to several different numerical self-force data and find good agreement, within estimated error bars. We also obtain, for the first time, independent analytical checks of the recently derived, comparable-mass fourth-post-Newtonian order dynamics [T. Damour, P. Jaranowski, and G. Schaefer, Nonlocal-in-time action for the fourth post-Newtonian conservative dynamics of two-body systems, Phys. Rev. D 89, 064058 (2014).].

When quantizing conformal dilaton gravity, there is a conformal anomaly which starts at two-loop order. This anomaly stems from evanescent operators on the divergent parts of the effective action. The general form of the finite counterterm, which is necessary in order to insure cancellation of the Weyl anomaly to every order in perturbation theory, has been determined using only conformal invariance. Those finite counterterms do not have any inverse power of any mass scale in front of them (precisely because of conformal invariance), and then they are not negligible in the low-energy deep infrared limit. The general form of the ensuing modifications to the scalar field equation of motion has been determined, and some physical consequences have been extracted.

In this work we model the quintessence potential in a Taylor series expansion, up to second order, around the present-day value of the scalar field. The field is evolved in a thawing regime assuming zero initial velocity. We use the latest data from the Planck satellite, baryonic acoustic oscillations observations from the Sloan Digital Sky Survey, and supernova luminosity distance information from Union2.1 to constrain our models parameters, and also include perturbation growth data from the WiggleZ, BOSS, and 6dF surveys. The supernova data provide the strongest individual constraint on the potential parameters. We show that the growth data performance is competitive with the other datasets in constraining the dark energy parameters we introduce. We also conclude that the combined constraints we obtain for our model parameters, when compared to previous works of nearly a decade ago, have shown only modest improvement, even with new growth of structure data added to previously existent types of data.

The recent ATLAS and CMS diphoton resonance excesses are explored in a simple $U(1)$ gauge theory extension of the Standard Model where the resonance is the Higgs boson of the $U(1)$ symmetry breaking, $\varphi$. This particle couples to exotic quarks which, through loops, can produce a large enough rate to explain the excess. Due to the choice of $U(1)$ charges, flavor constraints are naturally suppressed, allowing arbitrary flavor violation in the decays of the new quarks to up-type quarks, modifying their signal topologies. An additional heavy quark in the model decays to the lighter exotic quark by emitting either $\varphi$ or the $U(1)$ gauge boson $A_x$, giving extra signals containing diphoton and digluon resonances. Finally, the new Higgs can decay into $\gamma A_x$ and $Z{A}_x$, followed by $A_x$ decaying into Standard Model fermions through kinetic mixing. Thus, this model gives interesting modified signals to the general class of exotic quark models explaining the diphoton resonance.

We explore the possibility that the recently reported diphoton excess at ATLAS and CMS can be accommodated within a minimal extension of a left-right symmetric model. Our setup is able to simultaneously explain the Run 2 diphoton and Run 1 diboson excesses, while providing a standard thermal freeze-out of weak-scale dark matter. In this scenario, the 750 GeV neutral right-handed Higgs triplet is responsible for the diphoton excess. Interactions of this state with the neutral and charged components of dark matter multiplets provide the dominant mechanisms for production and decay. A striking signature of this model is the additional presence of missing energy in the diphoton channel.

We perform a model independent analysis of the helicity amplitudes at high energy for all the $2\to 2$ scattering processes involving gauge and Higgs bosons in the presence of anomalous $WWV$, $WWVV$, $VVH$, $VVHH$ ($V\equiv Z$, $\gamma$ and $W^{\pm }$), $HHHH$ and $HHH$ interactions. We obtain the perturbative unitarity constraints on anomalous couplings by demanding the vanishing of terms proportional to $s^2$ and $s^{3/2}$ in the helicity amplitudes. Using these constraints, we also compute the upper bound on all the anomalous couplings from terms linear in $s$. Further, assuming all anomalous couplings to have arisen only from dimension six operators, we show that the perturbative unitarity violation can be evaded up to $\sim 9\mathrm{TeV}$ corresponding to the best fit values of $f_{WW}/{\mathrm{\Lambda }}^2$ and $f_{BB}/{\mathrm{\Lambda }}^2$ from the combined analysis of Tevatron and LHC data.

In this article, we study the full one-loop SUSY contributions to the lepton flavor violating Higgs decay $h\to \tau \overline{\mu }$, within the context of the supersymmetric inverse seesaw model. We assume that both the right-handed neutrino masses, $M_R$, and their supersymmetric partner masses, $m_{{\tilde{\nu }}_R}$, are not far from the interesting $\mathcal{O}(\mathrm{TeV})$ energy scale, and we work with scenarios with large neutrino Yukawa couplings that transmit large lepton flavor violating effects. By exploring the behavior with the most relevant parameters, mainly $M_R$, $m_{{\tilde{\nu }}_R}$ and the trilinear sneutrino coupling $A_{\nu }$, we will look for regions of the parameter space where the enhancement of $\mathrm{BR}(h\to \tau \overline{\mu })$ is large enough to reach values at the percent level, which could explain the excess recently reported by CMS and ATLAS at the CERN Large Hadron Collider.

In the minimal supersymmetric standard models, neutralino dark matter with mass of $m_{\chi }\sim m_Z/2\sim 45\mathrm{GeV}$ and $m_{\chi }\sim m_h/2\sim 62\mathrm{GeV}$ can have the thermal relic abundance ${\mathrm{\Omega }}_{{\chi }_1}{h}^2\simeq 0.120$ via the $Z$- and Higgs-resonant annihilations, respectively, while avoiding all the current constraints. Phenomenology of such scenarios is determined only by three parameters, bino mass $M_1$, Higgsino mass $\mu$, and $\tan \beta$, in the limit that all other supersymmetric particles and heavy Higgs bosons are decoupled. In this paper, we comprehensively study the constraints and future prospects of the search for such Higgs- and $Z$-resonant neutralino dark matter. It is shown that almost all the parameter space of the scenario will be probed complementarily by the LHC search for the chargino and neutralinos, the direct detection experiments, and the Higgs invisible decay search at the ILC.

We have performed fits of the pseudoscalar masses and decay constants, from a variety of the RBC-UKQCD Collaboration’s domain wall fermion ensembles, to $SU(2)$ partially quenched chiral perturbation theory at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO). We report values for nine NLO and eight linearly independent combinations of NNLO partially quenched low-energy constants, which we compare to other lattice and phenomenological determinations. We discuss the size of successive terms in the chiral expansion and use our large set of low-energy constants to make predictions for mass splittings due to QCD isospin-breaking effects and the S-wave $\pi \pi$ scattering lengths. We conclude that, for the range of pseudoscalar masses explored in this work, $115\mathrm{MeV}\lesssim m_{\mathrm{PS}}\lesssim 430\mathrm{MeV}$, the NNLO $SU(2)$ expansion is quite robust and can fit lattice data with percent-scale accuracy.

The coupled quark Dyson-Schwinger and meson Bethe-Salpeter equations in rainbow-ladder truncation for spin-0 mesons are solved in the Wigner-Weyl phase in the chiral limit and beyond, retaining only the ultraviolet finite terms of the phenomenologically most successful Maris-Tandy interaction. This allows one to reveal and discuss the scalar and pseudoscalar meson masses in a chirally symmetric setting without additional medium effects. Independent of the current-quark mass, the found solutions are spacelike, i.e., have negative squared masses. The current-quark mass dependence of meson masses, leptonic decay constants and chiral condensate are illustrated in the Wigner-Weyl phase.

Multiple-parton interactions (MPI) play a vital role in hadron-hadron collisions. This paper presents a study of the MPIs with simulated $Z+\mathrm{jets}$ events in proton-proton collisions at a center-of-mass energy of 13 TeV. The events are simulated with powheg, followed by hadronization and parton showering using pythia8. The events with dimuon invariant mass in the range of $60–120\mathrm{GeV}/c^2$ are selected for the analysis. The charged particle jets having a minimum transverse momentum of $5\mathrm{GeV}/c$ and an absolute pseudorapidity less than 2 are used to construct the observables for measurements of the MPIs. The proposed observables and phase-space region presented in this paper are found to have enhanced sensitivity to MPIs. The increased sensitivity to MPIs will lead to precise constraints on the parameters of the MPI models.

We propose the study of unpolarized transverse momentum dependent gluon parton distributions as well as the effect of linearly polarized gluons on transverse momentum and rapidity distributions of $J/\psi$ and $\mathrm{\Upsilon }$ production within the framework of transverse momentum dependent factorization employing a color evaporation model (CEM) in an unpolarized proton-proton collision. We estimate the transverse momentum and rapidity distributions of $J/\psi$ and $\mathrm{\Upsilon }$ at LHCb, RHIC and AFTER energies using TMD evolution formalism.