The next generation of electron-hadron facilities has the potential for significantly improving our understanding of exotic hadrons. The $XYZ$ states have not been seen in photon-induced reactions so far. Their observation in such processes would provide an independent confirmation of their existence and offer new insights into their internal structure. Based on the known experimental data and the well-established quarkonium and Regge phenomenology, we give estimates for the exclusive cross sections of several $XYZ$ states. For energies near threshold we expect cross sections of few nanobarns for the $Z_c(3900{)}^{+}$ and upwards of tens of nanobarns for the $X(3872)$, which are well within reach of new facilities.

We systematically study mass spectra and decay properties of $P$-wave ${\mathrm{\Xi }}_c^{\prime }$ baryons of the $SU(3)$ flavor ${\mathbf{6}}_F$, using the methods of QCD sum rules and light-cone sum rules within the framework of heavy quark effective theory. Our results suggest that the three excited ${\mathrm{\Xi }}_c^0$ baryons recently observed by LHCb can be well explained as $P$-wave ${\mathrm{\Xi }}_c^{\prime }$ baryons: the ${\mathrm{\Xi }}_c(2923{)}^0$ and ${\mathrm{\Xi }}_c(2939{)}^0$ are partner states of $J^P=1/2^{-}$ and $3/2^{-}$, respectively, both of which contain one $\lambda$-mode orbital excitation; the ${\mathrm{\Xi }}_c(2965{)}^0$ has $J^P=3/2^{-}$ and also contains one $\lambda$-mode orbital excitation. We propose to search for another $P$-wave ${\mathrm{\Xi }}_c^{\prime }$ state of $J^P=5/2^{-}$ in the ${\mathrm{\Lambda }}_{c}K/{\mathrm{\Xi }}_c\pi$ mass spectral in future experiments. Its mass is about ${56}_{-35}^{+30}\mathrm{MeV}$ larger than the ${\mathrm{\Xi }}_c(2965{)}^0$, and its width is about ${18.1}_{-8.3}^{+19.7}\mathrm{MeV}$.

We investigate the phenomenological consequences of a strict gauge-invariant formulation of the Higgs particle. This requires a description of the observable scalar particle in terms of a bound state structure. Although this seems to be at odds with the common treatment of electroweak particle physics at first glance, the properties of the bound state can be described in a perturbative fashion due to the Fröhlich-Morchio-Strocchi (FMS) framework. In particular a relation between the bound-state Higgs and the elementary Higgs field is obtained within $R_{\xi }$ gauges such that the main quantitative properties of the conventional description reappear in leading order of the FMS expansion. Going beyond leading order, we show that the pole structure of the elementary and the bound-state propagator coincide to all orders in a perturbative expansion. However, slight deviations of scattering amplitudes containing off-shell Higgs contributions can be caused by the internal bound state structure. We perform a consistent perturbative treatment to all orders in the FMS expansion to quantify such deviations and demonstrate how gauge-invariant expressions arrange in a natural way at the one-loop level. This also provides a gauge-invariant Higgs spectral function which is not plagued by positivity violations or unphysical thresholds. Furthermore, the mass extracted from the gauge-invariant bound state is only logarithmically sensitive to the scale of new physics at one-loop order in contrast to its elementary counterpart.

This paper describes a search for beyond the Standard Model decays of the Higgs boson into a pair of new spin-0 particles subsequently decaying into $b$-quark pairs, $H\to aa\to (b\overline{b})(b\overline{b})$, using proton-proton collision data collected by the ATLAS detector at the Large Hadron Collider at center-of-mass energy $\sqrt{s}=13\mathrm{TeV}$. This search focuses on the range $15\mathrm{GeV}\le m_a\le 30\mathrm{GeV}$, where the decay products are collimated; it is complementary to a previous search in the same final state targeting the range $20\mathrm{GeV}\le m_a\le 60\mathrm{GeV}$, where the decay products are well separated. A novel strategy for the identification of the $a\to b\overline{b}$ decays is deployed to enhance the efficiency for topologies with small separation angles. The search is performed with $36{\mathrm{fb}}^{-1}$ of integrated luminosity collected in 2015 and 2016 and sets upper limits on the production cross section of $H\to aa\to (b\overline{b})(b\overline{b})$, where the Higgs boson is produced in association with a $Z$ boson.

A search is described for the production of a pair of bottom-type vectorlike quarks (VLQs), each decaying into a $b$ or $\overline{b}$ quark and either a Higgs or a $Z$ boson, with a mass greater than 1000 GeV. The analysis is based on data from proton-proton collisions at a 13 TeV center-of-mass energy recorded at the CERN LHC, corresponding to a total integrated luminosity of $137{\mathrm{fb}}^{-1}$. As the predominant decay modes of the Higgs and $Z$ bosons are to a pair of quarks, the analysis focuses on final states consisting of jets resulting from the six quarks produced in the events. Since the two jets produced in the decay of a highly Lorentz-boosted Higgs or $Z$ boson can merge to form a single jet, nine independent analyses are performed, categorized by the number of observed jets and the reconstructed event mode. No signal in excess of the expected background is observed. Lower limits are set on the VLQ mass at 95% confidence level equal to 1570 GeV in the case where the VLQ decays exclusively to a $b$ quark and a Higgs boson, 1390 GeV for when it decays exclusively to a $b$ quark and a $Z$ boson, and 1450 GeV for when it decays equally in these two modes. These limits represent significant improvements over the previously published VLQ limits.

Motivated by the recent progress in solving the large charge sector of conformal field theories, we revisit the mass-charge relation of boson stars asymptotic to global anti–de Sitter. We construct and classify a large number of electrically charged boson star solutions in a toy model and two supergravity models arising from the $SU(3)$ and $U(1{)}^4$ truncation of $D=4$ $SO(8)$ gauged maximal supergravity. We find a simple ansatz for the chemical potential that can fit the numerical data in striking accuracy for the full range of charge. Combining with the first law of thermodynamics, we can then evaluate the mass as a function of the charge and obtain the free energy in the fixed charge ensemble. We show that in the toy model, the ground state can be either the extremal Reissner-Nordström (RN) black hole or the boson stars depending on the parameter region. For the $SU(3)$ truncation, there always exists a boson star that has smaller free energy than the extremal RN black hole, in contrast to the $U(1{)}^4$ model where the extremal RN black hole is always the ground state. In all models, for boson star solutions with arbitrarily large charge, we show that the large charge expansion of the mass reproduces the same structure exhibited in the conformal field theory side.

The extended scalar-tensor and vector-tensor theories admit black hole solutions with the nontrivial profiles of the scalar and vector fields, respectively. The disformal transformation maps a solution in a class of the scalar-tensor or vector-tensor theories to that in another class, and hence it can be a useful tool to construct a new nontrivial solution from the known one. First, we investigate how the stationary and axisymmetric solutions in the vector-tensor theories without and with the $U(1)$ gauge symmetry are disformally transformed. We start from a stationary and axisymmetric solution satisfying the circularity conditions, and show that in both the cases the metric of the disformed solution in general does not satisfy the circularity conditions. Using the fact that a solution in a class of the vector-tensor theories with the vanishing field strength is mapped to that in a class of the shift-symmetric scalar-tensor theories, we derive the disformed stationary and axisymmetric solutions in a class of these theories, and show that the metric of the disformed solutions does not satisfy the circularity conditions if the scalar field depends on the time or azimuthal coordinate. We also confirm that in the scalar-tensor theories without the shift symmetry, the disformed stationary and axisymmetric solutions satisfy the circularity conditions. Second, we investigate the disformal transformations of the stationary and axisymmetric black hole solutions in the generalized Proca theory with the nonminimal coupling to the Einstein tensor, the shift-symmetric scalar-tensor theory with the nonminimal derivative coupling to the Einstein tensor, the Einstein-Maxwell theory, and the Einstein-conformally coupled scalar field theory. We show that the disformal transformations modify the causal properties of the spacetime, in terms of the number of horizons, the position of the black hole event horizon, and the appearance of the singularities at the finite radii.

Primordial black holes are analytically and numerically discussed based on the extended McVittie spacetime solution. By assuming that dark matter and radiation are the only sources of energy accreted by the forming central object, it is found that the black-hole mass evolution depends on the initial mass of the seed, the time in which the black hole emerges, and also on the average peculiar velocity of dark matter particles. Constraints on the initial conditions of the primordial black holes are derived from profiles of the black-hole accretion mechanism and cosmological environment. A large range of masses is compatible with our approach. In particular, masses of the order of ${10}^{10}{M}_{\odot }$ today may also be generated from small seeds. An incubation time for the emerging horizons is observed when the initial masses of the seeds are close to the particle-horizon mass. It is also argued that the McVittie-type description is consistent with the Schwarzschild solution as long as other astrophysical processes near the central object are neglected.

Baryon acoustic oscillations (BAO) provide a robust standard ruler and can be used to constrain the expansion history of the Universe at low redshift. Standard BAO analyses return a model-independent measurement of the expansion rate and the comoving angular diameter distance as a function of redshift, normalized by the sound horizon at radiation drag. However, this methodology relies on anisotropic distance distortions of a fixed, precomputed template (obtained in a given fiducial cosmology) in order to fit the observations. Therefore, it may be possible that extensions to the consensus $\mathrm{\Lambda }\mathrm{CDM}$ add contributions to the BAO feature that cannot be captured by the template fitting. We perform mock BAO fits to power spectra computed assuming cosmological models that modify the growth of perturbations prior to recombination in order to test the robustness of the standard BAO analysis. We find no significant bias in the BAO analysis for the models under study ($\mathrm{\Lambda }\mathrm{CDM}$ with a free effective number of relativistic species, early dark energy, and a model with interactions between neutrinos and a fraction of the dark matter), even for cases that do not provide a good fit to Planck measurements of the cosmic microwave background power spectra. This result supports the use of the standard BAO analysis and its measurements to perform cosmological parameter inference and to constrain exotic models. In addition, we provide a methodology to reproduce our study for different models and surveys, as well as discuss different options to handle eventual biases in the BAO measurements.

Magnetic fields are crucial in shaping the nonthermal emission of the TeV–PeV neutrinos of astrophysical origin seen by the IceCube neutrino telescope. The sources of these neutrinos are unknown, but if they harbor a strong magnetic field, then the synchrotron energy losses of the neutrino parent particles—protons, pions, and muons—leave characteristic imprints on the neutrino energy distribution and its flavor composition. We use high-energy neutrinos as “cosmic magnetometers” to constrain the identity of their sources by placing limits on the strength of the magnetic field in them. We look for evidence of synchrotron losses in public IceCube data: 6 years of High Energy Starting Events (HESE) and 2 years of Medium Energy Starting Events (MESE). In the absence of evidence, we place an upper limit of 10 kG–10 MG (95% C.L.) on the average magnetic field strength of the sources.

The chiral vortical effect (CVE) was derived first for massless fermions, within the framework of thermal quantum field theory. Recently, a dual description of the CVE, as related to the radiation from the horizon of a rotating black hole was suggested. Generalizing the latter approach to the case of photons, we encounter a crucial factor-of-2 difference from the predictions based on the thermal field theory. To elucidate the reason for this discrepancy, we turn to the limit of large spin $S$ of the massless particles. Within the gravitational approach, the CVE grows as $S^3$, while the flat-space relations result in a dependence which is linear in $S$. We also discuss briefly an alternative formulation of the presumed duality between the statistical and gravitational approaches.

In this work, we calculate the branching ratios and $CP$ violations of the $B_s^0\to a_0(980)a_0(980)$ decay modes with both charged and neutral $a_0(980)$ mesons and $B_s^0\to f_0(980)(f_0(500))f_0(980)(f_0(500))$ for the first time in the pQCD approach. Considering the recent observation of the BESIII collaboration that provide a direct information about the constituent two-quark components in the corresponding $a_0(980)$ wave functions, we regard the scalar mesons $a_0(980)$, $f_0(980)$, and $f_0(500)$ as the $q\overline{q}$ quark component in our present work, and then make predictions of these decay modes. The branching ratios of our calculations are at the order of the ${10}^{-4}\sim {10}^{-6}$ when we consider the mixing scheme. We also calculate the $CP$ violation parameters of these decay modes. The relatively large branching ratios make it easily to be tested by the running LHC-b experiments, and it can help us to understand both the inner properties and the QCD behavior of the scalar meson.

Axionlike particles (ALPs) are pseudo-Nambu-Goldstone bosons associated with spontaneously broken global symmetries emerging in many extensions of the Standard Model. Assuming the most general effective Lagrangian up to dimension-5 operators for an ALP interacting with the Standard Model fields, we investigate for the first time the sensitivity of the LHC13 to the ALP production in association with a di-jet. This study is focused on light ALPs which appear as invisible particles at the detector. Performing a realistic detector simulation and deploying a multivariate technique to best discriminate the signal from backgrounds, we set expected upper bounds on the ALP coupling to gluons. A comprehensive set of background processes is considered, and it is shown that this process provides significant sensitivity to the ALP-gluon coupling and the resulting bound is more stringent than those already obtained at the LHC. We also present prospects for the HE-LHC27 and FCC-hh100 and show that these future colliders are able to improve the limits from the LHC by roughly one order of magnitude.

In various extensions of the Standard Model of particle physics, and intriguingly even in the three-generation Standard Model without neutrino masses, neutrinos are allowed to have very tiny electric charges. After a review of the theoretical scenarios that allow the emergence of such charges, we discuss the existing observational limits and we derive new stringent direct upper bounds for the charges of the muon and tau neutrinos. We also point out a flavor-universal lower bound on neutrino charges which is obtained from the weak gravity conjecture, that is based on the hypothesis that gravity is the weakest force. We finally present a new flavor-universal upper bound on neutrino charges based on astrophysical observations of Magnetars.

Despite being less known, local bosonizations of fermionic systems exist in spatial dimensions higher than 1. Interestingly, the dual bosonic systems are subject to local constraints, as in theories with gauge freedom. These constraints effectively implement long distance exchange interactions. In this work, we study in detail one such system, proposed a long time ago. Properties of the constraints are elaborated for two-dimensional, rectangular lattices of arbitrary sizes. For several small systems, the constraints are solved analytically. It is checked that spectra of reduced spin Hamiltonians agree with the original fermionic ones. The equivalence is extended to fermions in the presence of background Wegner ${\mathbb{Z}}_2$ fields coupling to fermionic parity. This is illustrated by an explicit calculation for a particular configuration of Wegner’s variables. Finally, a possible connection with the recently proposed web of dualities is discussed.

Using $2.93{\mathrm{fb}}^{-1}$ of $e^{+}{e}^{-}$ annihilation data collected at a center-of-mass energy $\sqrt{s}=3.773\mathrm{GeV}$ with the BESIII detector operating at the BEPCII collider, we search for the semileptonic $D^{0(+)}$ decays into a $b_1(1235{)}^{-(0)}$ axial-vector meson for the first time. No significant signal is observed for either charge combination. The upper limits on the product branching fractions are ${\mathcal{B}}_{D^0\to b_1(1235{)}^{-}{e}^{+}{\nu }_e}·{\mathcal{B}}_{b_1(1235{)}^{-}\to \omega {\pi }^{-}}<1.12\times {10}^{-4}$ and ${\mathcal{B}}_{D^{+}\to b_1(1235{)}^0{e}^{+}{\nu }_e}·{\mathcal{B}}_{b_1(1235{)}^0\to \omega {\pi }^0}<1.75\times {10}^{-4}$ at the 90% confidence level.

We compute the semiclassical decay rate for Kerr black hole by deriving a one-way connection formula, relating the near horizon solution to the outgoing solution at infinity. In particular, we discuss the relevance of the Stokes phenomenon and show how it leads to a Boltzmann-like thermal weight factor by making use of the Stokes diagrams. We also give the exact result for the semiclassical greybody factor $e^{-2S}$, where $S$ is the leading order WKB action. We contrast our results with the work of Maldacena and Strominger [Phys. Rev. D 56, 4975 (1997), where the emission spectrum for a rotating black hole was computed locally via asymptotic matching. We find that the relative error of semiclassical decay rate with respect to asymptotic matching formula diminishes in the limit of large angular momentum, $l$, as expected. In this limit, the action assumes a compact form: $2S\sim (2l+1)(\mathrm{Log}(\frac{16}{z_0})-1)$, where $z_0$ is the cross ratio formed by the critical points (zeros) of the scattering potential.

The basic equations of the thermodynamic system give the relationship between the internal energy, entropy and volume of two neighboring equilibrium states. By using the functional relationship between the state parameters in the basic equation, we give the differential equation satisfied by the entropy of spacetime. We can obtain the entropy by solving the differential equation. This entropy is the sum of entropy corresponding to the two event horizons and the interaction term. The interaction term is the ratio between the location of the black hole horizon and the cosmological horizon. The entropic force, which is strikingly similar to the Lennard-Jones force between particles, varies with the ratio of the two event horizons. The discovery of this phenomenon makes us realize that the entropic force between the two horizons may be one of the candidates to promote the expansion of the universe.