Motivated by the stringy effects by modifying the local kinetic term of an Abelian Higgs field by the Gaussian kinetic term, we show that the Higgs field does not possess any instability; the Yukawa coupling between the scalar and the fermion, the gauge coupling, and the self interaction of the Higgs yields exponentially suppressed running at high energies, showing that such class of theory never suffers from vacuum instability. We briefly discuss its implications for the early Universe cosmology.

The discovery of a 125 GeV Higgs boson at the Large Hadron Collider strongly motivates direct searches for additional Higgs bosons. In a type I two Higgs doublet model there is a large region of parameter space at $\tan \beta \gtrsim 5$ that is currently unconstrained experimentally. We show that the process $gg\to H\to AZ\to ZZh$ can probe this region, and can be the discovery mode for an extended Higgs sector at the LHC. We analyze 9 promising decay modes for the $ZZh$ state, and we find that the most sensitive final states are $\ell \ell \ell \ell bb$, $\ell \ell jjbb$, $\ell \ell \nu \nu \gamma \gamma$ and $\ell \ell \ell \ell +$ missing energy.

We investigate in the Large Hadron Collider (LHC) environment the possibility that sizeable interference effects between a heavy charged Higgs boson signal produced via $bg\to t{H}^{-}$ ($+\mathrm{c}.\mathrm{c}.$) scattering and decaying via $H^{-}\to W^{-}A\to W^{-}b\overline{b}$ ($+\mathrm{c}.\mathrm{c}.$) and the irreducible background given by $bg\to t{W}^{-}b\overline{b}$ topologies could spoil current search approaches where the former and latter channels are treated separately. The rationale for this comes from the fact that a heavy charged Higgs state can have a large width, which can also happen for the $CP$-odd neutral Higgs state emerging in the ensuing decays, which in turn enables such interferences. We conclude that effects are very significant, both at the inclusive and exclusive level (i.e., both before and after $H^{\pm }$ selection cuts are enforced, respectively) and typically of a destructive nature. This, therefore, implies that currently established LHC reaches for heavy charged Higgs bosons require some level of rescaling. However, this is possible a posteriori, as the aforementioned $H^{\pm }$ selection cuts shape the interference contributions at the differential level in a way similar to that of the isolated $H^{\pm }$ signal, so there is no need to reassess the efficiency of the individual cuts. We show such effects quantitatively by borrowing benchmark points from different Yukawa types of a 2-Higgs doublet model parameter space for $H^{\pm }$ values starting from around 200 GeV.

Torsion models constitute a well-known class of extended quantum gravity models. In this work, one investigates the phenomenological consequences of a torsion field interacting with top quarks at the LHC. A torsion field could appear as a new heavy state characterized by its mass and couplings to fermions. This new state would form a resonance decaying into a top antitop pair. The latest ATLAS $t\overline{t}$ production results from LHC 13 TeV data are used to set limits on torsion parameters. The integrated luminosity needed to observe torsion resonance at the next LHC upgrades are also evaluated, considering different values for the torsion mass and its couplings to Standard Model fermions. Finally, prospects for torsion exclusion at the future LHC phases II and III are obtained using fast detector simulations.

We search for rare decays of $D$ mesons to hadrons accompanied by an electron-positron pair ($h(h^{(\prime )})e^{+}{e}^{-}$), using an $e^{+}{e}^{-}$ collision sample corresponding to an integrated luminosity of $2.93{\mathrm{fb}}^{-1}$ collected with the BESIII detector at $\sqrt{s}=3.773\mathrm{GeV}$. No significant signals are observed, and the corresponding upper limits on the branching fractions at the 90% confidence level are determined. The sensitivities of the results are at the level of ${10}^{-5}–{10}^{-6}$, providing a large improvement over previous searches.

In the present paper we consider the so-called effective cross section, a quantity which encodes the experimental knowledge on double parton scattering in hadronic collisions that has been accumulated so far. We show that the effective cross section, under some assumptions close to those adopted in its experimental extractions, can be used to obtain a range of mean transverse distance between an interacting parton pair in double parton scattering. Therefore, we have proved that the effective cross section offers a way to access information on the hadronic structure.

We investigate various aspects of energy extraction via the Penrose process in the Kerr-de Sitter spacetime. We show that the increase in the value of a positive cosmological constant, $\mathrm{\Lambda }$, always reduces the efficiency of this process. The Kerr-de Sitter spacetime has two ergospheres associated with the black hole and the cosmological event horizons. We prove by analyzing turning points of the trajectory that the Penrose process in the cosmological ergoregion is never possible. We next show that in this process both the black hole and cosmological event horizons’ areas increase, and the latter becomes possible when the particle coming from the black hole ergoregion escapes through the cosmological event horizon. We identify a new, local mass function instead of the mass parameter, to prove this generalized area theorem. This mass function takes care of the local spacetime energy due to the cosmological constant as well, including that which arises due to the frame-dragging effect due to spacetime rotation. While the current observed value of $\mathrm{\Lambda }$ is quite small, its effect in this process could be considerable in the early Universe scenario where its value is much larger, where the two horizons could have comparable sizes. In particular, the various results we obtain here are also evaluated in a triply degenerate limit of the Kerr-de Sitter spacetime we find, in which radial values of the inner, the black hole and the cosmological event horizons are nearly coincident.

We propose the Lagrangian formulation for describing the motion of a test particle in a general relativistic, stationary, and axially symmetric spacetime. The test particle is also affected by a radiation field, modeled as a coherent flux of photons traveling along the null geodesics of the background spacetime, including the general relativistic Poynting-Robertson effect. The innovative part of this work is to prove the existence of the potential linked to the dissipative action caused by the Poynting-Robertson effect in general relativity through the help of an integrating factor, depending on the energy of the system. Generally, such kinds of inverse problems involving dissipative effects might not admit a Lagrangian formulation; especially, in general relativity, there are no examples of such attempts in the literature so far. We reduce this general relativistic Lagrangian formulation to the classic case in the weak-field limit. This approach facilitates further studies in improving the treatment of the radiation field, and it contains, for example, some implications for a deeper comprehension of the gravitational waves.

We propose a data processing technique to cancel monopole and dipole noise sources (such as clock and ephemeris noises, respectively) in pulsar timing array searches for gravitational radiation. These noises are the dominant sources of correlated timing fluctuations in the lower-part ($\approx {10}^{-9}-{10}^{-8}\mathrm{Hz}$) of the gravitational wave band accessible by pulsar timing experiments. After deriving the expressions that reconstruct these noises from the timing data, we estimate the gravitational wave sensitivity of our proposed processing technique to single-source signals to be at least one order of magnitude higher than that achievable by directly processing the timing data from an equal-size array. Since arrays can generate pairs of clock and ephemeris-free timing combinations that are no longer affected by correlated noises, we implement with them the cross-correlation statistic to search for an isotropic stochastic gravitational wave background. We find the resulting optimal signal-to-noise ratio to be more than one order of magnitude larger than that obtainable by correlating pairs of timing data from arrays of equal size.

Infinite derivative gravity is able to resolve the big bang curvature singularity present in general relativity by using a simplifying ansatz. We show that it can also avoid the Hawking-Penrose singularity, by allowing defocusing of null rays through the Raychaudhuri equation. This occurs not only in the minimal case where we ignore the matter contribution but also in the case where matter plays a key role. We investigate the conditions for defocusing for the general case where this ansatz applies and also for more specific metrics, including a general Friedmann-Robertson-Walker metric and three specific choices of the scale factor which produce a bouncing Friedmann-Robertson-Walker universe.

We study the propagation of exact gravitational waves in the ghost-free bimetric theory. Our focus is on type-$N$ spacetimes compatible with the cosmological constants provided by the bigravity interaction potential, and particularly in the single class known by allowing at least a Killing symmetry: the AdS waves. They have the advantage of being represented by a generalized Kerr-Schild transformation from AdS spacetime. This entails a notorious simplification in bigravity by allowing to straightforwardly compute any power of its interaction square root matrix, opening the door to explore physically meaningful exact configurations. For these exact gravitational waves the complex dynamical structure of bigravity decomposes into elementary exact massless or massive excitations propagating on AdS. We use a complexified formulation of the Euler-Darboux equations to provide for the first time the general solutions to the massive version of the Siklos equation which rules the resulting AdS-wave dynamics, using an integral representation originally due to Poisson. Inspired by this progress, we tackle the subtle problem of how matter couples to bigravity and, more concretely, if this occurs through a composite metric, which is hard to handle in a general setting. Surprisingly, the Kerr-Schild ansatz brings again a huge simplification in how the related energy-momentum tensors are calculated. This allows us to explicitly characterize AdS waves supported by either a massless free scalar field or a wavefront-homogeneous Maxwell field. Considering the most general allowed Maxwell source instead is a highly nontrivial task, which we accomplish by again exploiting the complexified Euler-Darboux description and taking advantage of the classical Riemann method. In fact, this eventually allows us to find the most general configurations for any matter source.

Recently, DAMPE has released its first results on the high-energy cosmic-ray electrons and positrons (CREs) from about 25 GeV to 4.6 TeV, which directly detect a break at $\sim 1\mathrm{TeV}$. This result gives us an excellent opportunity to study the source of the CREs excess. In this work, we used the data for proton and helium flux (from AMS-02 and CREAM), $\overline{\mathrm{p}}/\mathrm{p}$ ratio (from AMS-02), positron flux (from AMS-02) and CREs flux (from DAMPE without the peak signal point at $\sim 1.4\mathrm{TeV}$) to do global fitting simultaneously, which can account for the influence from the propagation model, the nuclei and electron primary source injection, and the secondary lepton production precisely. For an extra source to interpret the excess in lepton spectrum, we consider two separate scenarios (pulsar and dark matter annihilation via leptonic channels) to construct the bump ($\gtrsim 100\mathrm{GeV}$) and the break at $\sim 1\mathrm{TeV}$. The result shows that (i) in the pulsar scenario, the spectral index of the injection should be ${\nu }_{\mathrm{psr}}\sim 0.65$ and the cut-off should be $R_c\sim 650\mathrm{GV}$; (ii) in dark matter scenario, the dark matter particle’s mass is $m_{\chi }\sim 1208\mathrm{GeV}$, and the cross section is $⟨\sigma v⟩\sim 1.48\times {10}^{-23}{\mathrm{cm}}^3{\mathrm{s}}^{-1}$. Moreover, in the dark matter scenario, the $\tau \overline{\tau }$ annihilation channel is highly suppressed, and a DM model is built to satisfy the fitting results.

Simulations of neutrino flavor evolution in compact merger environments have shown that neutrino flavor, and hence nucleosynthesis, can be strongly affected by the presence of matter-neutrino resonances (MNRs), where there is a cancelation between the matter and the neutrino potential. Simulations performed thus far follow flavor evolution along a single neutrino trajectory, but self-consistency requires all trajectories to be treated simultaneously, and it has not been known whether MNR phenomena would still occur in multiangle models. In this paper, we present the first fully multi-angle calculations of MNR. We find that familiar MNR phenomena, where neutrinos transform to a greater extent than anti-neutrinos and a feedback mechanism maintains the cancellation between the matter and neutrino potential, still occurs for a subset of angular bins, although the flavor transformation is not as efficient as in the single-angle case. In addition, we find other types of flavor transformation that are not seen in single-angle simulations. These flavor transformation phenomena appear to be robust and are present for a wide range of model parameters, as long as an MNR is present. Although computational constraints currently limit us to models with spherical symmetry, our results suggest that the presence of an MNR generally leads to large-scale neutrino flavor evolution in multiangle systems.

We investigate models of a heavy neutral gauge boson $Z^{\prime }$ coupling mostly to third generation quarks and second generation leptons. In this scenario, bottom quarks arising from gluon splitting can fuse into $Z^{\prime }$ allowing the LHC to probe it. In the generic framework presented, anomalies in $B$-meson decays reported by the LHCb experiment imply a flavor-violating $bs$ coupling of the featured $Z^{\prime }$ constraining the lowest possible production cross section. A novel approach searching for a $Z^{\prime }(\to \mu \mu )$ in association with at least one bottom-tagged jet can probe regions of model parameter space existing analyses are not sensitive to.

We investigate the electroweak vacuum stability in an extended version of the Standard Model that incorporates two additional singlet scalar fields and three right-handed neutrinos. One of these extra scalars plays the role of dark matter, while the other scalar not only helps make the electroweak vacuum stable but also opens up the low-mass window of the scalar singlet dark matter ($<500\mathrm{GeV}$). We consider the effect of large neutrino Yukawa coupling on the running of Higgs quartic coupling. We have analyzed the constraints on the model and identified the range of parameter space that is consistent with the neutrino mass, appropriate relic density, and direct search limits from the latest XENON 1T preliminary result as well as realized the stability of the electroweak vacuum up to the Planck scale.

We develop the dual description of ($2+1$)-dimensional SU(2) lattice gauge theory as interacting “Abelian-like” electric loops by using Schwinger bosons. “Point splitting” of the lattice enables us to construct explicit Hilbert space for the gauge invariant theory which in turn makes dynamics more transparent. Using path integral representation in phase space, the interacting closed loop dynamics is analyzed in the weak coupling limit to get the mass gap.

We study the decays of the antitriplet charmed baryon state $({\mathrm{\Xi }}_c^0,{\mathrm{\Xi }}_c^{+},{\mathrm{\Lambda }}_c^{+})$ based on the $SU(3)$ flavor symmetry. In particular, after predicting $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^{-}{\pi }^{+})=(15.7\pm 0.7)\times {10}^{-3}$ and $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Xi }}^{-}{\pi }^{+}{\pi }^{+})=(14.7\pm 8.4)\times {10}^{-3}$, we extract that $\mathcal{B}({\mathrm{\Xi }}_c^0\to \mathrm{\Lambda }{K}^{-}{\pi }^{+},\mathrm{\Lambda }{K}^{+}{K}^{-},{\mathrm{\Xi }}^{-}{e}^{+}{\nu }_e)=(16.8\pm 2.3,0.45\pm 0.11,48.7\pm 17.4)\times {10}^{-3}$ and $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to p{K}_s^0{K}_s^0,{\mathrm{\Sigma }}^{+}{K}^{-}{\pi }^{+},{\mathrm{\Xi }}^0{\pi }^{+}{\pi }^0,{\mathrm{\Xi }}^0{e}^{+}{\nu }_e)=(1.3\pm 0.8,13.8\pm 8.0,33.8\pm 21.9,33.8_{-22.6}^{+21.9})\times {10}^{-3}$. We also find that $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Xi }}^0\eta ,{\mathrm{\Xi }}^0{\eta }^{\prime })=(1.7_{-1.7}^{+1.0},8.6_{-6.3}^{+11.0})\times {10}^{-3}$, $\mathcal{B}({\mathrm{\Xi }}_c^0\to {\mathrm{\Lambda }}^0\eta ,{\mathrm{\Lambda }}^0{\eta }^{\prime })=(1.6_{-0.8}^{+1.2},9.4_{-6.8}^{+11.6})\times {10}^{-4}$ and $\mathcal{B}({\mathrm{\Xi }}_c^{+}\to {\mathrm{\Sigma }}^{+}\eta ,{\mathrm{\Sigma }}^{+}{\eta }^{\prime })=(28.4_{-6.9}^{+8.2},13.2_{-11.9}^{+24.0})\times {10}^{-4}$. These ${\mathrm{\Xi }}_c$ decays with the branching ratios of $O({10}^{-4}–{10}^{-3})$ are clearly promising to be observed by the BESIII and LHCb experiments.

Using a sample of $4.48\times {10}^8\psi (3686)$ events collected with the BESIII detector at the BEPCII collider, we study the two-photon decays of the pseudoscalar mesons ${\pi }^0$, $\eta$, ${\eta }^{\prime }$, $\eta (1405)$, $\eta (1475)$, $\eta (1760)$, and $X(1835)$ in $J/\psi$ radiative decays using $\psi (3686)\to {\pi }^{+}{\pi }^{-}J/\psi$ events. The ${\pi }^0$, $\eta$, and ${\eta }^{\prime }$ mesons are clearly observed in the two-photon mass spectra, and the branching fractions are determined to be $B(J/\psi \to \gamma {\pi }^0\to 3\gamma )=(3.57\pm 0.12\pm 0.16)\times {10}^{-5}$, $B(J/\psi \to \gamma \eta \to 3\gamma )=(4.42\pm 0.04\pm 0.18)\times {10}^{-4}$, and $B(J/\psi \to \gamma {\eta }^{\prime }\to 3\gamma )=(1.26\pm 0.02\pm 0.05)\times {10}^{-4}$, where the first error is statistical and the second is systematic. No clear signal for $\eta (1405)$, $\eta (1475)$, $\eta (1760)$ or $X(1835)$ is observed in the two-photon mass spectra, and upper limits at the 90% confidence level on the product branching fractions are obtained.

The final state proposal [G. T. Horowitz and J. M. Maldacena, J. High Energy Phys. 04 (2004) 008] is an attempt to relax the apparent tension between string theory and semiclassical arguments regarding the unitarity of black hole evaporation. Authors Bousso and Stanford [Phys. Rev. D 89, 044038 (2014)] analyze thought experiments where an infalling observer first verifies the entanglement between early and late Hawking modes and then verifies the interior purification of the same Hawking particle. They claim that “probabilities for outcomes of these measurements are not defined” and therefore suggest that “the final state proposal does not offer a consistent alternative to the firewall hypothesis.” We show, in contrast, that one may define all the relevant probabilities based on the so-called ABL rule [Y. Aharonov, P. G. Bergmann, and J. L. Lebowitz, Phys. Rev. 134, B1410 (1964)], which is better suited for this task than the decoherence functional. We thus assert that the analysis of Bousso and Stanford cannot yet rule out the final state proposal.