Search

New phenomena involving pseudorapidity and azimuthal correlations among final-state particles in pp collisions at the LHC can hint at the existence of hidden sectors beyond the Standard Model. In this paper we rely on a correlated-cluster picture of multiparticle production, which was shown to account for the ridge effect, to assess the effect of a hidden sector on three-particle correlations concluding that there is a potential signature of new physics that can be directly tested by experiments using well-known techniques. [ABSTRACT FROM AUTHOR]

We study the impact of a hidden sector beyond the Standard Model, e.g. a Hidden Valley model, on factorial moments and cumulants of multiplicity distributions in multiparticle production with a special emphasis on the prospects for LHC results. [ABSTRACT FROM AUTHOR]

The possible burst occurred in location and temporal consistence with gravitational wave event GW150914, as reported by Fermi GBM, offers a new way of constraining models with extra dimensions. Using the time delay in arrival of the gamma ray transient observed by Fermi Gamma-ray Burst Monitor (GMB) relative to the gravitational waves event triggered by the LIGO detectors we investigate the size of the spherical brane-universe expanding in multi-dimensional space–time. It is shown that a joint observation of gravitational waves in association with gamma ray burst can provide a very stringent bound on the spatial curvature of the brain. [ABSTRACT FROM AUTHOR]

For the data on the observation times and directions of the motion of extensive air showers, which are observed at two stations of the GELATICA network, for the first time we apply the method we have developed previously for identifying pairs of mutually remote extensive air showers, the ancestor particles of which arose, possibly, in a single process. A brief description of the GELATICA network, a review of the properties of used samples of data on shower observations at two stations of the network during the 2019–2021 session, and the result of applying the above method to them are given. Some properties of a single peculiar pair of remote showers are discussed. A side question arose about the cause of the observed temporal asymmetry in the locations of the regions of mutual approach of independent primary cosmic ray particles. [ABSTRACT FROM AUTHOR]

Particle production in small systems (proton-proton and proton-nucleus collisions) and in large systems (nucleus-nucleus collisions) at high-energy and high-density frontiers displays both similar and different behaviors. These data include, but are not limited to, transverse momentum spectra, anisotropic flows, statistical or dynamical fluctuations of light flavor particles, heavy flavor particles, jets, and leptons. These properties are related to the signatures of the formation of a new state of matter, quark-gluon plasma (QGP), which is predicated by quantum chromodynamics (QCD). [Extracted from the article]

Abstract The observation by the IceCube Collaboration of a high-energy (E ≳ 200 TeV) neutrino from the direction of the blazar TXS 0506+056 and the coincident observations of enhanced γ -ray emissions from the same object by MAGIC and other experiments can be used to set stringent constraints on Lorentz violation in the propagation of neutrinos that is linear in the neutrino energy: Δ v = − E / M 1 , where Δ v is the deviation from the velocity of light, and M 1 is an unknown high energy scale to be constrained by experiment. Allowing for a difference in neutrino and photon propagation times of ∼10 days, we find that M 1 ≳ 3 × 10 16 GeV. This improves on previous limits on linear Lorentz violation in neutrino propagation by many orders of magnitude, and the same is true for quadratic Lorentz violation. [ABSTRACT FROM AUTHOR]

The photon mass, m γ , can in principle be constrained using measurements of the dispersion measures (DMs) of fast radio bursts (FRBs), once the FRB redshifts are known. The DM of the repeating FRB 121102 is known to < 1 % , a host galaxy has now been identified with high confidence, and its redshift, z , has now been determined with high accuracy: z = 0.19273 ( 8 ) . Taking into account the plasma contributions to the DM from the Intergalactic medium (IGM) and the Milky Way, we use the data on FRB 121102 to derive the constraint m γ ≲ 2.2 × 10 − 14 eV c − 2 ( 3.9 × 10 − 50 kg ). Since the plasma and photon mass contributions to DMs have different redshift dependences, they could in principle be distinguished by measurements of more FRB redshifts, enabling the sensitivity to m γ to be improved. [ABSTRACT FROM AUTHOR]

The frequency-dependent time delays in fast radio bursts (FRBs) can be used to constrain the photon mass, if the FRB redshifts are known, but the similarity between the frequency dependences of dispersion due to plasma effects and a photon mass complicates the derivation of a limit on m γ . The dispersion measure (DM) of FRB 150418 is known to ∼ 0.1 % , and there is a claim to have measured its redshift with an accuracy of ∼ 2 % , but the strength of the constraint on m γ is limited by uncertainties in the modelling of the host galaxy and the Milky Way, as well as possible inhomogeneities in the intergalactic medium (IGM). Allowing for these uncertainties, the recent data on FRB 150418 indicate that m γ ≲ 1.8 × 10 − 14 eV c − 2 ( 3.2 × 10 − 50 kg ), if FRB 150418 indeed has a redshift z = 0.492 as initially reported. In the future, the different redshift dependences of the plasma and photon mass contributions to DM can be used to improve the sensitivity to m γ if more FRB redshifts are measured. For a fixed fractional uncertainty in the extra-galactic contribution to the DM of an FRB, one with a lower redshift would provide greater sensitivity to m γ . [ABSTRACT FROM AUTHOR]