We investigate cosmological models in a recently proposed geometrical theory of gravity, in which the scalar field appears as part of the spacetime geometry. We extend the previous theory to include a scalar potential in the action. We solve the vacuum field equations for different choices of the scalar potential and give a detailed analysis of the solutions. We show that, in some cases, a cosmological scenario is found that seems to suggest the appearance of a geometric phase transition. We build a toy model, in which the accelerated expansion of the early Universe is driven by pure geometry.

As a result of the Standard Model chiral anomalies, baryon number is violated in the early Universe in the presence of a hypermagnetic field with varying helicity. We investigate whether the matter/antimatter asymmetry of the Universe can be created from the decaying helicity of a primordial (hyper)magnetic field before and after the electroweak phase transition. In this model, baryogenesis occurs without ($B-L$)-violation, since the ($B+L$) asymmetry generated by the hypermagnetic field counteracts the washout by electroweak sphalerons. At the electroweak crossover, the hypermagnetic field becomes an electromagnetic field, which does not source ($B+L$). Although the sphalerons remain in equilibrium for a time, washout is avoided since the decaying magnetic helicity sources chirality. The relic baryon asymmetry is fixed when the electroweak sphaleron freezes out. Under reasonable assumptions, a baryon asymmetry of $n_B/s\simeq 4\times {10}^{-12}$ can be generated from a maximally helical, right-handed (hyper)magnetic field that has a field strength of $B_0\simeq {10}^{-14}\text{Gauss}$ and coherence length of ${\lambda }_0\simeq 1\mathrm{pc}$ today. Relaxing an assumption that relates ${\lambda }_0$ to $B_0$, the model predicts $n_B/s\gtrsim {10}^{-10}$, which could potentially explain the observed baryon asymmetry of the Universe.

Little Higgs models are promising constructs to solve the hierarchy problem affecting the Higgs boson mass for generic new physics. However, their preservation of lepton universality forbids them to account for the $H\to \tau \mu$ CMS hint and at the same time respect (as they do) the severe limits on $H\to \mu e$ inherited from the nonobservation of $\mu \to e\gamma$. We compute the predictions of the simplest little Higgs model for the $H\to \ell {\ell }^{\prime }$ decays and conclude that the measurement of any of these decays at LHC (even with a much smaller rate than currently hinted) would, under reasonable assumptions, disfavor this model. This result is consistent with our earlier observation of very suppressed lepton flavor violating semileptonic tau decays within this model.

We analyze the prospects for observing the light and heavy $CP$-even neutral Higgs bosons ($\varphi =h$ and $H$) in their decays into flavor violating $b\overline{s}$ channels (including charge conjugation) at the proposed Large Hadron electron Collider (LHeC), with $\sqrt{s}\approx 1.3\mathrm{TeV}$, in the framework of a 2-Higgs doublet model (2HDM) Type III, assuming a four-zero texture in the Yukawa matrices and a general Higgs potential. We consider theoretically consistent scenarios in agreement with current experimental data from flavor and Higgs physics. We investigate the charged current production process ${\nu }_e\varphi q$ in presence of flavor violating decays of the Higgs bosons, that lead to a $3\text{-jets}+{\cancel{E}}_T$ signature. We demand exactly two jets, one tagged $b$-jet and one light-flavor jet, all in the central rapidity region. The remaining jet (originated by the remnant quark $q$) is tagged in the forward or backward regions and this together with a central jet veto (not more than one light-flavor jet) are essential criterions to enhance the signal–to–background rates. We consider the most relevant standard model (SM) backgrounds, treating $c$-jets separately from light-flavor and gluon ones, while allowing for mistagging. We find that the SM-like Higgs boson, $h$, would be accessible within several parameter configurations of our model at approximately the $1\text{−}2\sigma$ level with $100{\mathrm{fb}}^{-1}$ of data. We also find that the heaviest neutral Higgs boson, $H$, with mass up to 150 GeV, would have a $1\sigma$ significance for the same data sample. At the end of the LHeC running, one would have ten times data accumulation and for all the Higgs masses the significances are enhanced so as to allow for detection of both the $h$ and $H$ state. Hence, one of the most viable extensions of 2HDMs with flavor changing neutral currents (FCNCs) generated at tree level but controlled by a four-zero texture approach in the Yukawa matrices, as opposed to the adoption of ad hoc discrete symmetries, could be put under scrutiny at a future $ep$ machine.

We develop methods to calculate the electroweak gauge boson contribution to the effective Higgs potential in the context of composite Higgs models, using lattice gauge theory. The calculation is analogous to that of the electromagnetic mass splitting of the pion multiplet in QCD. We discuss technical details of carrying out this calculation, including modeling of the momentum and fermion-mass dependence of the underlying current-current correlation function, direct integration of the correlation function over momentum, and fits based on the minimal-hadron approximation. We show results of a numerical study using valence overlap fermions, carried out in an SU(4) gauge theory with two flavors of Dirac fermions in the two-index antisymmetric representation.

We investigate Landau gauge $SU(3)$ Yang-Mills theory in a systematic vertex expansion scheme for the effective action with the functional renormalization group. Particular focus is put on the dynamical creation of the gluon mass gap at nonperturbative momenta and the consistent treatment of quadratic divergences. The nonperturbative ghost and transverse gluon propagators as well as the momentum-dependent ghost-gluon, three-gluon and four-gluon vertices are calculated self-consistently with the classical action as the only input. The apparent convergence of the expansion scheme is discussed and within the errors, our numerical results are in quantitative agreement with available lattice results.

We present an analysis of data on single inclusive pion production measured by the LHCf Collaboration in high-energy proton-proton and proton-nucleus at ultraforward rapidities, $8.8\le y\le 10.8$. We also analyze forward RHIC data for calibration purposes. Our analysis relies on the use of a Monte Carlo event generator that combines a perturbative description of the elementary scattering process at partonic level based on the hybrid formalism of the color glass condensate with an implementation of hadronization in the framework of the Lund string fragmentation model. This procedure allows us to reach values of the momenta of the produced particles as low as detected experimentally, $p_t\sim 0.1\mathrm{GeV}$. We achieve a good description of single inclusive spectra of charged particles and neutral pions at the RHIC and the LHC, respectively, and nuclear modification factors for proton-lead collisions at the LHC. Our results add evidence to the idea that particle production in the domain of a very small Bjorken $x$ is dominated by the saturation effects encoded in the unintegrated gluon distribution of the target. With forward particle production being of key importance in the development of air showers, we stress that this approach allows for a theoretically controlled extrapolation of our results to the scale of ultra-high-energy cosmic rays, thus serving as the starting point for future works on this topic.

Motivated by TeV-scale neutrino mass models, we propose a systematic treatment of heavy neutrino ($N$) production at hadron colliders. Our simple and efficient modeling of the vector boson fusion (VBF) $W^{\pm }\gamma \to N{\ell }^{\pm }$ and $N{\ell }^{\pm }+nj$ signal definitions resolve collinear and soft divergences that have plagued past studies, and is applicable to other color-singlet processes, e.g., associated Higgs $(W^{\pm }h)$, sparticle $({\tilde{\ell }}^{\pm }\widetilde{{\nu }_{\ell }})$, and charged Higgs $(h^{\pm \pm }{h}^{\mp })$ production. We present, for the first time, a comparison of all leading $N$ production modes, including both gluon fusion (GF) $gg\to Z^{*}/h^{*}\to N\stackrel{(-)}{{\nu }_{\ell }}$ and VBF. We obtain fully differential results up to next-to-leading order (NLO) in QCD accuracy using a Monte Carlo tool chain linking feynrules, nloct, and madgraph5_amc@nlo. Associated model files are publicly available. At the 14 TeV LHC, the leading order GF rate is small and comparable to the NLO $N{\ell }^{\pm }+1j$ rate; at a future 100 TeV Very Large Hadron Collider, GF dominates for $m_N=300–1500\mathrm{GeV}$, beyond which VBF takes the lead.

Separate samples of charged-current pion production events representing two semi-inclusive channels ${\nu }_{\mu }\text{−}\mathrm{CC}({\pi }^{+})$ and ${\overline{\nu }}_{\mu }\text{−}\mathrm{CC}({\pi }^0)$ have been obtained using neutrino and antineutrino exposures of the MINERvA detector. Distributions in kinematic variables based upon ${\mu }^{\pm }$-track reconstructions are analyzed and compared for the two samples. The differential cross sections for muon production angle, muon momentum, and four-momentum transfer $Q^2$ are reported, and cross sections versus neutrino energy are obtained. Comparisons with predictions of current neutrino event generators are used to clarify the role of the $\mathrm{\Delta }(1232)$ and higher-mass baryon resonances in CC pion production and to show the importance of pion final-state interactions. For the ${\nu }_{\mu }\text{−}\mathrm{CC}({\pi }^{+})$ [${\overline{\nu }}_{\mu }\text{−}\mathrm{CC}({\pi }^0)$] sample, the absolute data rate is observed to lie below (above) the predictions of some of the event generators by amounts that are typically 1-to- $2\sigma$. However the generators are able to reproduce the shapes of the differential cross sections for all kinematic variables of either data set.

We report a measurement of the $CP$-violation parameter ${\phi }_1$ obtained in a time-dependent analysis of $B^0\to {\overline{D}}^{(*)0}{h}^0$ decays followed by ${\overline{D}}^0\to K_S^0{\pi }^{+}{\pi }^{-}$ decay. A model-independent measurement is performed using the binned Dalitz plot technique. The measured value is ${\phi }_1=11.7°\pm 7.8°(\mathrm{stat})\pm 2.1°(\mathrm{syst})$. Treating $\sin 2{\phi }_1$ and $\cos 2{\phi }_1$ as independent parameters, we obtain $\sin 2{\phi }_1=0.43\pm 0.27(\mathrm{stat})\pm 0.08(\mathrm{syst})$ and $\cos 2{\phi }_1=1.06\pm 0.33{(\mathrm{stat})}_{-0.15}^{+0.21}(\mathrm{syst})$. The results are obtained with a full data sample of $772\times 10^{6}B\overline{B}$ pairs collected near the $\mathrm{\Upsilon }(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider.

We report on the results of the E06-014 experiment performed at Jefferson Lab in Hall A, where a precision measurement of the twist-3 matrix element $d_2$ of the neutron ($d_2^n$) was conducted. The quantity $d_2^n$ represents the average color Lorentz force a struck quark experiences in a deep inelastic electron scattering event off a neutron due to its interaction with the hadronizing remnants. This color force was determined from a linear combination of the third moments of the ${}^3\mathrm{He}$ spin structure functions, $g_1$ and $g_2$, after nuclear corrections had been applied to these moments. The structure functions were obtained from a measurement of the unpolarized cross section and of double-spin asymmetries in the scattering of a longitudinally polarized electron beam from a transversely and a longitudinally polarized ${}^3\mathrm{He}$ target. The measurement kinematics included two average $Q^2$ bins of $3.2{\mathrm{GeV}}^2$ and $4.3{\mathrm{GeV}}^2$, and Bjorken-$x$ $0.25\le x\le 0.90$ covering the deep inelastic and resonance regions. We have found that $d_2^n$ is small and negative for $⟨Q^2⟩=3.2{\mathrm{GeV}}^2$, and even smaller for $⟨Q^2⟩=4.3{\mathrm{GeV}}^2$, consistent with the results of a lattice QCD calculation. The twist-4 matrix element $f_2^n$ was extracted by combining our measured $d_2^n$ with the world data on the first moment in $x$ of $g_1^n$, ${\mathrm{\Gamma }}_1^n$. We found $f_2^n$ to be roughly an order of magnitude larger than $d_2^n$. Utilizing the extracted $d_2^n$ and $f_2^n$ data, we separated the Lorentz color force into its electric and magnetic components, $F_E^{y,n}$ and $F_B^{y,n}$, and found them to be equal and opposite in magnitude, in agreement with the predictions from an instanton model but not with those from QCD sum rules. Furthermore, using the measured double-spin asymmetries, we have extracted the virtual photon-nucleon asymmetry on the neutron $A_1^n$, the structure function ratio $g_1^n/F_1^n$, and the quark ratios $(\mathrm{\Delta }u+\mathrm{\Delta }\overline{u})/(u+\overline{u})$ and $(\mathrm{\Delta }d+\mathrm{\Delta }\overline{d})/(d+\overline{d})$. These results were found to be consistent with deep-inelastic scattering world data and with the prediction of the constituent quark model but at odds with the perturbative quantum chromodynamics predictions at large $x$.

We compute the dominant, logarithmically enhanced radiative corrections to the electron spectrum in bound muon decay in the whole experimentally interesting range. The corrected spectrum fits well with the results from the TWIST Collaboration. The remaining theoretical error, dominated by the nuclear charge distribution, can be reduced in the muon-electron conversion searches by measuring the spectrum slightly below the new physics signal window.

Using the non-Abelian Dirac-Born-Infeld action we find an effective matrix model that describes the dynamics of weakly interacting giant gravitons wrapped on three-spheres in the anti–de Sitter (AdS) part of ${\mathrm{AdS}}_5\times S^5$ at high energies with two angular momenta on the $S^5$. In parallel we consider the limit of $\mathcal{N}=4$ super Yang-Mills theory near a certain unitarity bound where it reduces to the quantum mechanical theory called $SU(2)$ spin matrix theory. We show that the exact same matrix model that describes the giant gravitons on the string theory side also provides the effective description in the strong coupling and large energy limit of the spin matrix theory. Thus, we are able to match nonsupersymmetric dynamics of D-branes on ${\mathrm{AdS}}_5\times S^5$ to a finite-$N$ regime in $\mathcal{N}=4$ super Yang-Mills theory near a unitarity bound.

We find the first binary black hole event horizon with a toroidal topology. It has been predicted that generically the event horizons of merging black holes should briefly have a toroidal topology. However, such a phase has never been seen in numerical simulations. Instead, in all previous simulations, the topology of the event horizon transitions directly from two spheres during the inspiral to a single sphere as the black holes merge. We find a coordinate transformation to a foliation of spacelike hypersurfaces that “cut a hole” through the event horizon surface, resulting in a toroidal event horizon, thus reconciling the numerical work with theoretical expectations. The demonstration requires extremely high numerical precision, which is made possible by a new event horizon code described in a companion paper. A torus could potentially provide a mechanism for violating topological censorship. However, these toroidal event horizons satisfy topological censorship by construction, because we can always trivially apply the inverse coordinate transformation to remove the topological feature.

With Advanced LIGO detecting the gravitational waves emitted from a pair of merging black holes in late 2015, we have a new perspective into the strong field regime of binary black hole systems. Event horizons are the defining features of such black hole spacetimes. We introduce a new code for locating event horizons in numerical simulations based on a Delaunay triangulation on a topological sphere. The code can automatically refine arbitrary regions of the event horizon surface to find and explore features such as the hole in a toroidal event horizon, as discussed in our companion paper. We also investigate various ways of integrating the geodesic equation and find evolution equations that can be integrated efficiently with high accuracy.

We present a new supersymmetric, asymptotically flat, black hole solution to five-dimensional $U(1{)}^3$ supergravity which is regular on and outside an event horizon of lens space topology $L(2,1)$. The solution has seven independent parameters and uplifts to a family of $1/8$-supersymmetric D1-D5-P black brane solutions to type IIB supergravity. The decoupling limit is asymptotically ${\mathrm{AdS}}_3\times S^3\times T^4$, with a near-horizon geometry that is a twisted product of the near-horizon geometry of the extremal Bañados-Teitelboim-Zanelli black hole and $L(2,1)\times T^4$, although it is not (locally) a product space in the bulk. We show that the decoupling limit of a special case of the black lens is related to that of a black ring by spectral flow, thereby supplying an account of its entropy. Analogous solutions of $U(1{)}^N$ supergravity are also presented.

In this paper, we consider a dyonic charged anti-de Sitter black hole, which is a holographic dual of a van der Waals fluid. We use logarithm-corrected entropy and study thermodynamics of the black hole and show that holographic picture is still valid. Critical behaviors and stability are also discussed. Logarithmic corrections arises due to thermal fluctuations, which are important when the size of black hole is small. So, thermal fluctuations are interpreted as a quantum effect. It means that we can see the quantum effect of a black hole, which is a gravitational system.

We consider Gauss-Bonnet (GB) gravity in general dimensions, which is nonminimally coupled to a scalar field. By choosing a scalar potential of the type $V(\varphi )=2{\mathrm{\Lambda }}_0+\frac{1}{2}{m}^2{\varphi }^2+{\gamma }_4{\varphi }^4$, we first obtain large classes of scalar hairy black holes with spherical/hyperbolic/planar topologies that are asymptotic to locally anti– de Sitter (AdS) space-times. We derive the first law of black hole thermodynamics using Wald formalism. In particular, for one class of the solutions, the scalar hair forms a thermodynamic conjugate with the graviton and nontrivially contributes to the thermodynamical first law. We observe that except for one class of the planar black holes, all these solutions are constructed at the critical point of GB gravity where there exist unique AdS vacua. In fact, a Lifshitz vacuum is also allowed at the critical point. We then construct many new classes of neutral and charged Lifshitz black hole solutions for an either minimally or nonminimally coupled scalar and derive the thermodynamical first laws. We also obtain new classes of exact dynamical AdS and Lifshitz solutions which describe radiating white holes. The solutions eventually become AdS or Lifshitz vacua at late retarded times. However, for one class of the solutions, the final state is an AdS space-time with a globally naked singularity.

The origin of ultrahigh energy cosmic rays (UHECR) is still unknown. However, great progress has been achieved in past years due to the good quality and large statistics in experimental data collected by the current observatories. The data of the Pierre Auger Observatory show that the composition of UHECRs becomes progressively lighter starting from $10^{17}\mathrm{eV}$ up to $\sim 10^{18.3}\mathrm{eV}$ and then, beyond that energy, it becomes increasingly heavier. These analyses are subject to important systematic uncertainties due to the use of hadronic interaction models that extrapolate lower energy accelerator data to the highest energies. Although proton models of UHECRs are disfavored by these results, they cannot be completely ruled out. It is well known that the energy spectra of gamma rays and neutrinos, produced during propagation of these very energetic particles through the intergalactic medium, are a useful tool to constrain the spectrum models. In particular, it has recently been shown that the neutrino upper limits obtained by IceCube challenge the proton models at 95% C.L. In this work we study the constraints imposed by the extragalactic gamma-ray background, measured by Fermi-LAT, on proton models of UHECRs. In particular, we make use of the extragalactic gamma-ray background flux, integrated from 50 GeV to 2 TeV, that originates in point sources, which has recently been obtained by the Fermi-LAT Collaboration, in combination with the neutrino upper limits, to constrain the emission of UHECRs at high redshifts ($z>1$), in the context of the proton models.

We calculate for the first time the phonon excitation rate in the outer crust of a neutron star due to scattering from light dark matter (LDM) particles gravitationally boosted into the star. We consider dark matter particles in the sub-GeV mass range scattering off a periodic array of nuclei through an effective scalar-vector interaction with nucleons. We find that LDM effects cause a modification of the net number of phonons in the lattice as compared to the standard thermal result. In addition, we estimate the contribution of LDM to the ion-ion thermal conductivity in the outer crust and find that it can be significantly enhanced at large densities. Our results imply that for magnetized neutron stars the LDM-enhanced global conductivity in the outer crust will tend to reduce the anisotropic heat conduction between perpendicular and parallel directions to the magnetic field.