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Harmonic Hybrid Inflation
No full textWe present a mechanism for realizing hybrid inflation using two axion fields with a purely non-perturbatively generated scalar potential. The structure of scalar potential is highly constrained by the discrete shift symmetries of the axions. We show that harmonic hybrid inflation generates observationally viable slow-roll inflation for a wide range of initial conditions. This is possible while accommodating certain UV arguments favoring constraints f≲MP and Δϕ60≲MP on the axion periodicity and slow-roll field range, respectively. We discuss controlled ℤ2-symmetry breaking of the adjacent axion vacua as a means of avoiding cosmological domain wall problems. Including a minimal form of ℤ2-symmetry breaking into the minimally tuned setup leads to a prediction of primordial tensor modes with the tensor-to-scalar ratio in the range 10−4≲r≲0.01, directly accessible to upcoming CMB observations. Finally, we outline several avenues towards realizing harmonic hybrid inflation in type IIB string theory
Studies of charm and beauty hadron long-range correlations in pp and pPb collisions at LHC energies
No full textMeasurements of the second Fourier harmonic coefficient () of the azimuthal distributions of prompt and nonprompt D mesons (the latter coming from beauty hadron decays) produced in pp and pPb collisions are presented. The data samples are collected by the CMS experiment at nucleon-nucleon center-of-mass energies of 13 and 8.16 TeV, respectively. In high multiplicity pp collisions, signals for prompt charm hadrons are reported for the first time, and are found to be comparable to those for light-flavor hadron species over a transverse momentum () range of 2-6 GeV. Compared at similar event multiplicities, the prompt D meson values in pp and pPb collisions are similar in magnitude. The values for open beauty hadrons are extracted for the first time via nonprompt D mesons in pPb collisions. For in the range of 2-5 GeV, the results suggest that for nonprompt D mesons are smaller than those for prompt D mesons. These new measurements indicate a positive charm hadron in pp collisions and suggest a mass dependence in between charm and beauty hadrons in the pPb system. These results provide insights into the origin of heavy-flavor quark collectivity in small systems
Measurements of pp ZZ production cross sections and constraints on anomalous triple gauge couplings at 13 TeV
No full textThe production of Z boson pairs in proton-proton (pp) collisions, pp (Z/)(Z/) 2 2, where = e or , is studied at a center-of-mass energy of 13 TeV with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137 fb, collected during 2016-2018. The ZZ production cross section, (pp ZZ) = 17.2 0.3 (stat) 0.5 (syst) 0.4 (theo) 0.3 (lumi) pb, measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region 60 120 GeV is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous ZZZ and ZZ couplings
Topologization of β-antimonene on via proximity effects
No full textTopological surface states usually emerge at the boundary between a topological and a conventional insulator. Their precise physical character and spatial localization depend on the complex interplay between the chemical, structural and electronic properties of the two insulators in contact. Using a lattice-matched heterointerface of single and double bilayers of β-antimonene and bismuth selenide, we perform a comprehensive experimental and theoretical study of the chiral surface states by means of microscopy and spectroscopic measurements complemented by first-principles calculations. We demonstrate that, although β-antimonene is a trivial insulator in its free-standing form, it inherits the unique symmetry-protected spin texture from the substrate via a proximity effect that induces outward migration of the topological state. This “topologization” of β-antimonene is found to be driven by the hybridization of the bands from either side of the interface
Iodination of cyclo‐E‐Complexes (E=P, As)
No full textIn a high-yield one-pot synthesis, the reactions of )] (M=Fe (1), Ru (2)) with resulted in the selective formation of salts (3, 4). The products comprise unprecedented all-cis tripodal triphosphino-cyclotriphosphine ligands. The iodination of (6) gave, in addition to salts of the rare (in 7) and (in 8) anions, the first di-cationic Fe-As triple decker complex (9). In contrast, the iodination of (10) did not result in the full cleavage of the M-As bonds. Instead, a number of dinuclear complexes were obtained: (11) represents the first Ru-As5 triple decker complex, thus completing the series of monocationic complexes (M=Fe, Ru; E=P, As). (12) crystallizes as a racemic mixture of both enantiomers, while (13) crystallizes as a symmetric and an asymmetric isomer and features a unique tetramer of {AsI} arsinidene units as a middle deck
State-selective cross sections from ring polymer molecular dynamics
No full textUnderstanding the influence of different forms of energy (eg, translational, vibrational, rotational) on chemical reactions is a key goal and great challenge in physical chemistry. Very recently, we proposed a new approach to obtain state‐selective cross sections that approximately include quantum effects such as zero‐point energy and tunneling. The method is a combination of the widely used quasiclassical trajectory approach (QCT) and the ring polymer molecular dynamics method and thus is numerically very efficient and easily employed. Here, we present a detailed description of the method and exhaustive tests of its accuracy and applicability. The robustness of the approach is tested, as well as the convergence with the number of beads. The approach is then applied to several prototypical X + H2(ν = 0, 1), X = Mu, H, D, F, Cl reactions over a wide range of collision energies. Good agreement with rigorous quantum dynamics simulations is found for most cases. Encouraging improvement over QCT results is found for particular cases, while only a small increase in numerical cost is required
Measurement of the associated production of a boson with charm or bottom quark jets in proton-proton collisions at =13 TeV
No full textRatios of cross sections, σ(Z+c jets)/σ(Z+jets), σ(Z+b jets)/σ(Z+jets), and σ(Z+c jets)/σ(Z+b jets) in the associated production of a Z boson with at least one charm or bottom quark jet are measured in proton-proton collisions at s=13 TeV. The data sample, collected by the CMS experiment at the CERN LHC, corresponds to an integrated luminosity of 35.9 fb-1, with a fiducial volume of pT>30 GeV and |η|25 GeV and |η|<2.4, and the dilepton mass satisfies 71<mZ<111 GeV. The measured values are σ(Z+c jets)/σ(Z+jets)=0.102±0.002±0.009, σ(Z+b jets)/σ(Z+jets)=0.0633±0.0004±0.0015, and σ(Z+c jets)/σ(Z+b jets)=1.62±0.03±0.15. Results on the inclusive and differential cross section ratios as functions of jet and Z boson transverse momentum are compared with predictions from leading and next-to-leading order perturbative quantum chromodynamics calculations. These are the first measurements of the cross section ratios at 13 TeV
Search for the imprint of axion-like particles in the highest-energy photons of hard -ray blazars
No full textAxion-like particles (ALPs), predicted in theories beyond the Standard Model, can have observational effects on the transparency of the Universe to γ rays in the presence of magnetic fields. In this work, we search for effects compatible with the existence of ALPs with 80 months of data from the Fermi Large Area Telescope, by comparing the distributions of observed highest energy photons from sources beyond redshifts of z ≥ 0.1 with theoretical predictions in the presence of ALPs. We find no evidence for an increased γ-ray transparency due to ALPs and therefore we set limits on the ALPs parameters assuming a value of the intergalactic magnetic field strength of 1 nG. Photon-ALP couplings above are excluded for ALP masses ≲ 3.0 neV . As the allowed magnetic field parameter space is large, we also test lower magnetic field strengths and no constraints can be set for B≤0.1 nG below the CAST limit. These constraints exclude a region of the parameter space not covered by other -ray telescopes and are compatible with limits imposed by other experiments
Temporal X-ray Reconstruction using Temporal and Spectral Measurements at LCLS
No full textTransverse deflecting structures (TDSs) are widely used in accelerator physics to measure the longitudinal density of particle bunches. When used in combination with a dispersive section, the whole longitudinal phase space density can be imaged. At the Linac Coherent Light Source (LCLS), the installation of such a device downstream of the undulators enables the reconstruction of the X-ray temporal intensity profile by comparing longitudinal phase space distributions with lasing on and lasing off. However, the resolution of this TDS is limited to around 1 fs rms (root mean square), and therefore, it is not possible to resolve single self-amplified spontaneous emission (SASE) spikes within an X-ray photon pulse. By combining the power spectrum from a high resolution photon spectrometer and the temporal structure from the TDS, the overall resolution is enhanced, thus allowing the observation of temporal, single SASE spikes. The combined data from the spectrometer and the TDS is analysed using an iterative algorithm to obtain the actual intensity profile.In this paper, we present some improvements to the reconstruction algorithm as well as real data taken at LCLS
Search for a doubly-charged bound state in inclusive decays and via direct production in collisions at = 10.520, 10.580, and 10.867 GeV
No full textWe report the results of a first search for a doubly-charged bound state, denoted the , in and inclusive decays and via direct production in collisions at = 10.520, 10.580, and 10.867 GeV. The search uses data accumulated with the Belle detector at the KEKB asymmetric-energy collider. No significant signals are observed in the invariant-mass spectra of all studied modes. The 90\% credibility level upper limits on their product branching fractions in and inclusive decays (), and the product values of Born cross section and branching fraction in collisions () at = 10.520, 10.580, and 10.867 GeV under different assumptions of masses varying from 4.13 to 4.17 GeV/, and widths varying from 0 to 5 MeV are obtained