A mechanism of inflation from higher dimensions compactification is studied. An early Universe capable of providing exponential growth for some dimensions and exponential contraction for others, giving therefore an explanation for the big size of the observed four-dimensional Universe as well as the required smallness of the extra dimensions is obtained. The mechanism is formulated in the context of dynamical spacetime theory, which produces a unified picture of dark energy, dark matter, and can also provide a bounce for the volume of the Universe. A negative vacuum energy puts an upper bound on the maximum volume, and the bounce imposes a lower bound. So in the early Universe the volume oscillates, but in each oscillation the extra dimensions contract exponentially, and the ordinary dimension expand exponentially. The dynamical spacetime theory provides a natural way to exit from the inflation compactification epoch since the scalar field that drives the vacuum energy can smoothly climb into small positive values of vacuum energy, which is the end of the inflation compactification. A semianalytic solution for a step function potential is also studied, where all of these effects are shown, especially the jump of the vacuum energy effect only on the derivative of dynamical spacetime vector field, and not the volume or its derivatives, which match smoothly.

The Laser Interferometer Space Antenna is a joint European Space Agency–NASA space mission to detect and study milliherz cosmic gravitational waves. The trajectories followed by its three spacecraft result in unequal- and time-varying arms, requiring use of the time-delay interferometry (TDI) postprocessing technique to cancel the laser phase noises affecting the heterodyne one-way Doppler measurements. Although the second-generation formulation of TDI cancels the laser phase noises when the array is both rotating and “flexing,” second-generation TDI combinations for which the phase fluctuations of the onboard ultrastable oscillators can be calibrated out have not appeared yet in the literature. In this article, we present the solution of this problem by generalizing to the realistic LISA trajectory the ultrastable oscillators calibration algorithm derived by Tinto et al. for a static configuration.

Tests of the weak equivalence principle (WEP) can reveal a new, composition dependent, force of nature, or disprove many models of new physics. For the first time, such a test is being successfully carried out in space by the MICROSCOPE satellite. Early results show no violation of the WEP sourced by the Earth for Pt and Ti test masses with random errors (after 8.26 d of integration time) of about 1 part in $10^{14}$ and systematic errors of the same magnitude. This result improves by about 10 times over the best ground tests with rotating torsion balances despite 70 times less sensitivity to differential accelerations, thanks to the much stronger driving signal in orbit. The measurement is limited by thermal noise from internal damping in the gold wires used for electrical grounding, related to their fabrication and clamping. This noise was shown to decrease when the spacecraft was set to rotate faster than planned. The result will improve by the end of the mission, as thermal noise decreases with more data. Not so systematic errors. We investigate major nongravitational effects and find that MICROSCOPE’s “zero-check” sensor, with test masses both made of Pt, does not allow their separation from the signal. The early test reports an upper limit of systematic errors in the Pt-Ti sensor, which are not detected in the Pt-Pt one, hence would not be distinguished from a violation. Once all the integration time available is used to reduce random noise, there will be no time left to check systematics. MICROSCOPE demonstrates the huge potential of space for WEP tests of very high precision and indicates how to reach it. To realize the potential, a new experiment needs the spacecraft to be in rapid, stable rotation around the symmetry axis (by conservation of angular momentum), needs high quality state-of-the-art mechanical suspensions as in the most precise gravitational experiments on ground, and must allow multiple checks to discriminate a violation signal from systematic errors. The design of the “Galileo Galilei” (GG) experiment, aiming to test the WEP to 1 part in $10^{17}$ unites all the needed features, indicating that a quantum leap in space is possible provided the new experiment heeds the lessons of MICROSCOPE.

We study the excitation of the electric current of chiral fermions along the external magnetic field, known as the chiral magnetic effect, in the presence of the background axial-vector field. The calculation of the current is based on the exact solution of the Dirac equation for these fermions accounting for the external fields. First, this solution was obtained for massive particles and, then, we consider the chiral limit, which is used in the anomalous current computation. We obtain that, in this situation, the anomalous current does not contain the direct contribution of the axial-vector field. This result is compared with findings of other authors.

The production of the heavy quarkonium, i.e., $|(c\overline{b})[n]⟩$ (or $|(b\overline{c})[n]⟩$), $|(c\overline{c})[n]⟩$, and $|(b\overline{b})[n]⟩$- quarkonium [$|(Q\overline{Q^{\prime }})[n]⟩$-quarkonium for short], through Higgs $H^0$ boson semiexclusive decays is evaluated within the nonrelativistic quantum chromodynamics (NRQCD) framework, where [$n$] stands for the production of the two color-singlet $S$-wave states, $|(Q\overline{Q^{\prime }})[{{}^{1}S}_0{]}_{\mathbf{1}}⟩$ and $|(Q\overline{Q^{\prime }})[{{}^{3}S}_1{]}_{\mathbf{1}}⟩$, the production of the four color-singlet $P$-wave states, i.e., $|(Q\overline{Q^{\prime }})[{{}^{1}P}_0{]}_{\mathbf{1}}⟩$, $|(Q\overline{Q^{\prime }})[{{}^{3}P}_J{]}_{\mathbf{1}}⟩$ (with $J=[0,1,2]$). Moreover, according to the velocity scaling rule of the NRQCD, the production of the two color-octet components, $|(Q\overline{Q^{\prime }})g[{{}^{1}S}_0{]}_{\mathbf{8}}⟩$ and $|(Q\overline{Q^{\prime }})g[{{}^{3}S}_1{]}_{\mathbf{8}}⟩$, are also taken into account. The “improved trace technology” to derive the simplified analytic expressions at the amplitude level is adopted, which shall be useful for dealing with these decay channels. If all higher heavy quarkonium states decay completely to the ground states, it should be obtained $\mathrm{\Gamma }(H^0\to |(c\overline{b})[{{}^{1}S}_0{]}_{\mathbf{1}}⟩)=15.14\mathrm{KeV}$, $\mathrm{\Gamma }(H^0\to |(c\overline{c})[{{}^{1}S}_0{]}_{\mathbf{1}}⟩)=1.547\mathrm{KeV}$, and $\mathrm{\Gamma }(H^0\to |(b\overline{b})[{{}^{1}S}_0{]}_{\mathbf{1}}⟩)=1.311\mathrm{KeV}$. The production of $5.6\times {10}^5$ Bc meson, $4.7\times {10}^4$ charmonium meson, and $4.9\times {10}^4$ bottomonium meson per year in Higgs decays at the HE/HL-LHC can be obtained.

We compute the contributions to rare top decays $t\to cZ$ and $t\to c{h}_1$ from the scalar sector in the two Higgs doublet model type III with $CP$ violation, where $h_1$ is the Standard Model Higgs boson. The branching ratios for $\mathrm{BR}(t\to cZ)$ and $\mathrm{BR}(t\to c{h}_1)$ are obtained as a function of the model parameters. In particular, the $\mathrm{BR}(t\to cZ)$ can increase its value up to ${10}^{-3}$ for $\tan \beta =1$ and masses for the additional Higgs bosons of $m_{h_2,h_3,H^{\pm }}\sim 0.5\mathrm{TeV}$. Meanwhile $\mathrm{BR}(t\to c{h}_1)$ can reach values of the order of $\sim {10}^{-2}$. We constrain the model parameters (mixing angles of the neutral scalar fields in the $CP$ violation context and $\tan \beta$) using the reported values of the signal strengths $R_{XX}$ and $b\to s\gamma$ process.

One of the main purposes of long-baseline neutrino experiments is to unambiguously measure the $CP$ violating phase in the neutrino sector within the three neutrino oscillation picture. In the presence of physics beyond the Standard Model, the determination of the $CP$ phase will be more difficult, due to the already known degeneracy problem. Working in the framework of nonstandard interactions (NSI), we compute the appearance probabilities in an exact analytical formulation and analyze the region of parameters where this degeneracy problem is present. We also discuss some cases where the degeneracy of the NSI parameters can be probed in long-baseline experiments.

The application of a uniform background magnetic field makes standard quark operators utilizing gauge-covariant Gaussian smearing inefficient at isolating the ground state nucleon at nontrivial field strengths. In the absence of QCD interactions, Landau modes govern the quark energy levels. There is evidence that residual Landau mode effects remain when the strong interaction is turned on. Here, we introduce novel quark operators constructed from the two-dimensional $U(1)$ Laplacian eigenmodes that describe the Landau levels of a charged particle on a periodic finite lattice. These eigenmode-projected quark operators provide enhanced precision for calculating nucleon energy shifts in a magnetic field. Using asymmetric source and sink operators, we are able to encapsulate the predominant effects of both the QCD and QED interactions in the interpolating fields for the neutron. The neutron magnetic polarizability is calculated using these techniques on the $32^3\times 64$ dynamical QCD lattices provided by the PACS-CS Collaboration. In conjunction with a chiral effective-field theory analysis, we obtain a neutron magnetic polarizability of ${\beta }^n=2.05(25)(19)\mathbf{\times }{10}^{-4}{\mathrm{fm}}^3$, where the numbers in parentheses describe statistical and systematic uncertainties.

Many experiments that are conducted to study the hadron spectrum rely on peripheral resonance production. Hereby, the rapidity gap allows the process to be viewed as an independent fragmentation of the beam and the target, with the beam fragmentation dominated by production and decays of meson resonances. We test this separation by determining the kinematic regimes that are dominated by factorizable contributions, indicating the most favorable regions to perform this kind of experiments. In doing so, we use a Regge model to analyze the available world data of charge exchange meson production with beam momentum above 5 GeV in the laboratory frame that are not dominated by either pion or Pomeron exchanges. We determine the Regge residues and point out the kinematic regimes which are dominated by factorizable contributions.

We perform a complete analysis of the spectrum of all the states in the $\mathcal{N}=2$ quark model harmonic oscillator band with $N_f=3$ in the large $N_c$ limit including the often disregarded antisymmetric multiplet $[\mathbf{20},1^{+}]$. We include configuration mixing effects. We find that the states in the $[\mathbf{56},L^{+}]$ and $[\mathbf{70},L^{+}]$ with $L=0$, 2 fall into nine towers of degenerate states. We find that nonstrange antisymmetric states fall into three towers and respond to the same structure as the states in the $[\mathbf{70},1^{-}]$ multiplet. We also show explicitly the compatibility of these results and the scattering resonance picture.

The light-front quark model analysis of the meson-photon transition form factor $F_{P\gamma }(Q^2)$ amenable both to the spacelike region ($Q^2>0$) and the timelike region ($Q^2<0$) provides a systematic twist expansion of $Q^2{F}_{P\gamma }(Q^2)$ for the high $|Q^2|$ region. Investigating $F_{P\gamma }(Q^2)(P={\eta }_c,{\eta }_b)$ for the entire kinematic regions of $Q^2$, we examine the twist-2 and twist-3 distribution amplitudes of $({\eta }_c,{\eta }_b)$ mesons in the light-front quark model and quantify their contributions to $Q^2{F}_{({\eta }_c,{\eta }_b)\gamma }(Q^2)$. Our numerical results for the normalized transition form factor $F_{({\eta }_c,{\eta }_b)\gamma }(Q^2)/F_{({\eta }_c,{\eta }_b)\gamma }(0)$ and the decay width ${\mathrm{\Gamma }}_{({\eta }_c,{\eta }_b)\to \gamma \gamma }$ are compared with the available data, checking the sensitivity of our model to the variation of the constituent quark masses.

The hidden charm $X(3872)$ resonance is usually thought to be a $D^{*0}{\overline{D}}^0$ meson-antimeson molecule with quantum numbers $J^{PC}=1^{++}$. If this is the case, there is the possibility that there might be three body bound states with two charmed mesons and a charmed antimeson. Here we argue that the theoretical existence of this type of three body molecules is expected from heavy quark spin symmetry. If applied to the two body sector, this symmetry implies that the interaction of the $D^{*0}{\overline{D}}^{*0}$ meson-antimeson pair in the $J^{PC}=2^{++}$ channel is the same as in the $J^{PC}=1^{++}$ $D^{*0}{\overline{D}}^0$ case. From this we can infer that the $J^P=3^{-}$ $D^{*0}{D}^{*0}{\overline{D}}^{*0}$ molecule will be able to display the Efimov effect if the scattering length of the $2^{++}$ channel is close enough to the unitary limit. Heavy quark spin symmetry also indicates that the $J^P=2^{-}$ $D^{*0}{D}^{*0}{\overline{D}}^0$ molecule is analogous to the $J^P=3^{-}$ $D^{*0}{D}^{*0}{\overline{D}}^{*0}$ one. That is, it can also have a geometric spectrum. If we consider these triply heavy trimers in the isospin symmetric limit, the Efimov effect disappears and we can in principle predict the fundamental state of the $2^{-}$ $D^{*}{D}^{*}\overline{D}$ and $3^{-}$ $D^{*}{D}^{*}{\overline{D}}^{*}$ systems. The same applies to the $B^{*}{B}^{*}{\overline{B}}^{*}$ system: if the $Z_b(10650)$ is an isovector $B^{*}{\overline{B}}^{*}$ molecule then the $0^{-}$ isodoublet and the $1^{-}$, $2^{-}$ isoquartet $B^{*}{B}^{*}{\overline{B}}^{*}$ trimers might bind, but do not display Efimov physics. Finally from heavy flavour symmetry it can be argued that scattering in the $BD$ two-body system might be resonant. This would in turn imply the possibility of Efimov physics in the $BBD$ three body system.

$\mathrm{ER}=\mathrm{EPR}$ allows us to think of quantum teleportation as communication of quantum information through spacetime wormholes connecting entangled systems. The conditions for teleportation render the wormhole traversable so that a quantum system entering one end of the ERB will, after a suitable time, appear at the other end. Teleportation requires the transfer of classical information outside the horizon, but the classical bit-string carries no information about the teleported system; the teleported system passes through the ERB leaving no trace outside the horizon. In general the teleported system will retain a memory of what it encountered in the wormhole. This phenomenon could be observable in a laboratory equipped with quantum computers.

We compute the axial quasinormal modes of static neutron stars in scalar tensor theory. In particular, we employ various realistic equations of state including nuclear, hyperonic and hybrid matter. We investigate the fundamental curvature mode and compare the results with those of general relativity. We find that the frequency of the modes and the damping time are reduced for the scalarized neutron stars. In addition, we confirm and extend the universal relations for quasinormal modes known in general relativity to this wide range of realistic equations of state for scalarized neutron stars and confirm the universality of the scaled frequency and damping time in terms of the scaled moment of inertia as well as compactness for neutron stars with and without scalarization.

We study the formation of classical singularities in generalized Brans-Dicke theories that are natural extensions to Brans-Dicke where the kinetic term is modified by a new coupling function $\omega (\phi )$. We discuss the asymptotic limit $\omega (\phi )\to \infty$ and show that the system generically does not approach general relativity. Given the arbitrariness of $\omega (\phi )$, one can search for coupling functions chosen specifically to avoid classical singularities. However, we prove that this is not the case. Homogeneous and spherically symmetric collapsing objects form singularities for arbitrary coupling functions. On the other hand, expanding cosmological scenarios are completely free of big rip type singularities. In an expanding universe, the scalar field behaves at most as stiff matter, which makes these cosmological solutions asymptotically approach general relativity.

We investigate an extension of the $\mathrm{\Lambda }\mathrm{CDM}$ model where the dark matter (DM) is coupled to photons, inducing a nonconservation of the numbers of particles for both species, where the DM particles are allowed to dilute throughout the cosmic history with a small deviation from the standard evolution decaying into photons, while the associated scattering processes are assumed to be negligible. In addition, we consider the presence of massive neutrinos and the effective number of species $N_{\mathrm{eff}}$ as a free parameter. The effects of the DM-photon coupling on the cosmic microwave background (CMB) and matter power spectra are analyzed. We derive the observational constraints on the model parameters by using the data from Planck CMB, baryonic acoustic oscillation (BAO) measurements, the recently measured new local value of the Hubble constant from the Hubble Space Telescope, and large scale structure (LSS) information from the abundance of galaxy clusters. The DM-photon coupling parameter ${\mathrm{\Gamma }}_{\gamma }$ is constrained to ${\mathrm{\Gamma }}_{\gamma }\le 1.3\times {10}^{-5}$ (at 95% C.L.) from the joint analysis carried out by using all the mentioned data sets. The neutrino mass scale $\sum m_{\nu }$ upper bounds at 95% C.L. are obtained as $\sum m_{\nu }\sim 0.9\mathrm{eV}$ and $\sum m_{\nu }\sim 0.4\mathrm{eV}$ with and without the LSS data, respectively. We observe that the DM-photon coupling can cause significant changes in the best fit value of $N_{\mathrm{eff}}$ but yields statistical ranges of $N_{\mathrm{eff}}$ compatible with the standard predictions, and we do not find any evidence of dark radiation. Due to nonconservation of photons in our model, we also evaluate and analyze the effects on the BAO acoustic scale at the drag epoch. The DM-photon coupling model yields high values of Hubble constant consistent with the local measurement, and thus alleviates the tension on $H_0$.

We present the most detailed computation to date of the 21-cm global signal and fluctuations at $z\gtrsim 500$. Our calculations include a highly precise estimate of the Wouthuysen-Field effect and the first explicit calculation of the impact of free-free processes, the two dominant components of the signal at $z\gtrsim 800$. We implement a new high-resolution Lyman-$\alpha$ radiative transfer calculation, coupled to a state-of-the-art primordial recombination code. Using these tools, we find a global signal from 21-cm processes alone of roughly 0.01 mK at $z\sim 1000$, slightly larger than it would be without the Wouthuysen-Field effect but much weaker than previous estimates including this effect. We also find that this signal is swamped by a smooth $1–2\mathrm{mK}$ signal due to free-free absorption at high redshift by the partially ionized gas along the line of sight. In addition, we estimate the amplitude of 21-cm fluctuations, of order $\sim {10}^{-7}\mathrm{mK}$ at $z\sim 1000$. Unfortunately, we find that, due to the brightness of the low-frequency sky, these fluctuations will not be observable beyond $z\sim$ a few hundred by even extremely futuristic observations. The 21-cm fluctuations are exponentially suppressed at higher redshifts by the large free-free optical depth, making this the ultimate upper redshift limit for 21-cm surveys.

It has recently been demonstrated analytically that the two-point correlation function for pairs of neutrinos may contain information about the size of the protoneutron star formed in a Galactic core-collapse supernova. The information about the size of the source emerges via the neutrino equivalent of intensity interferometry originally used by Hanbury-Brown and Twiss with photons to measure the radii of stars. However the analytic demonstration of neutrino intensity interferometry with supernova neutrinos made a number of approximations: that the two neutrinos had equal energies, that the neutrinos were emitted at simultaneous times from two points and that they were detected simultaneously at two detection points that formed a plane with the emission points. These approximations need to be relaxed in order to better determine the feasibility of neutrino intensity interferometry for supernovae neutrinos in a more realistic scenario. In this paper we further investigate the feasibility of intensity interferometry for supernova neutrinos by relaxing all the approximations made in the earlier study. We find that, while relaxing any one assumption reduces the correlation signal, the relaxation of the assumption of equal times of detection is by far the largest detrimental factor. For neutrino energies of order $\sim 15\mathrm{MeV}$ and a supernova distance of $L=10\mathrm{kpc}$, we show that in order to observe the interference pattern in the two-point correlation function of the neutrino pairs, the timing resolution of a detector needs to be on the order of $\lesssim {10}^{-21}\mathrm{s}$ if the initial neutrino wave packet has a size of ${\sigma }_x\sim {10}^{-11}\mathrm{cm}$.

We explore the possibility that bound states involving dark matter particles could be detected by resonance searches at the LHC and the generic implications of such scenarios for indirect and direct detection. We demonstrate that resonance searches are complementary to monojet searches and can probe dark matter masses above 1 TeV with current LHC data. We argue that this parameter regime, in which the bound-state resonance channel is the most sensitive probe of the dark sector, arises most naturally in the context of nontrivial dark sectors with large couplings, nearly degenerate dark matter–like states, and multiple force carriers. If dark sector bound states are present and can be detected at the LHC, annihilation of dark matter particles in our galactic halo may occur either with a minimal Sommerfeld enhancement that may be appreciable or through radiative bound-state formation, leading to large signals in indirect searches. We calculate these complementary constraints, which favor either models in which the bound state–forming dark matter constitutes a small fraction of the total density or models in which the late-time annihilation is suppressed at low velocities or late times. We present concrete examples of models that satisfy all these constraints and in which the LHC resonance search is the most sensitive probe of the dark sector.

We study the residues of ${\mathrm{\Lambda }}_Q$-type baryons (${\mathrm{\Lambda }}_Q$ and ${\mathrm{\Xi }}_Q^A$) $(Q=b,c)$ and ${\mathrm{\Sigma }}_Q$-type baryons (${\mathrm{\Sigma }}_Q^{(*)}$, ${\mathrm{\Xi }}_Q^{S(*)}$ and ${\mathrm{\Omega }}_Q^{(*)}$) in the quark-diquark model within the Bethe-Salpeter (BS) formalism. These residues can be used, e.g., in the calculations of the amplitudes in the scattering processes. After constructing the baryonic currents in the BS formalism, we derive the relations between the BS wave functions and the residues for these baryons. The BS equations are solved numerically with the kernel including the scalar confinement and the one-gluon-exchange terms and with the covariant instantaneous approximation being employed in the calculations. Finally, we obtain the numerical values of the residues $0.103\mathrm{GeV}\sim 0.224\mathrm{GeV}$ for ${\mathrm{\Lambda }}_Q$, $0.143\mathrm{GeV}\sim 0.215\mathrm{GeV}$ for ${\mathrm{\Xi }}_Q^A$, $0.262\mathrm{GeV}\sim 0.361\mathrm{GeV}$ for ${\mathrm{\Sigma }}_Q^{(*)}$, $0.313\mathrm{GeV}\sim 0.460\mathrm{GeV}$ for ${\mathrm{\Xi }}_Q^{S(*)}$ and $0.473\mathrm{GeV}\sim 0.571\mathrm{GeV}$ for ${\mathrm{\Omega }}_Q^{(*)}$ in the ranges of the parameters in our model.