Prospects For Future Measurements Research Articles

Four-top quark physics at the LHC

The production of four top quarks presents a rare process in the Standard Model that provides unique opportunities and sensitivity to Standard Model observables including potential enhancement of many popular new physics extensions. This article summarises the latest experimental measurements of the four-top quark production cross section at the LHC. An overview is provided detailing interpretations of the experimental results regarding the top quark Yukawa coupling in addition to the limits on physics beyond the Standard Model. Further, prospects for future measurements and opportunities offered by this challenging final state are given herein.

CP asymmetry in τ→KSπντ decays within the standard model and beyond

Motivated by the $2.8\sigma$ discrepancy observed between the BaBar measurement and the Standard Model prediction of the CP asymmetry in $\tau\to K_S\pi\nu_\tau$ decays, as well as the prospects of future measurements at Belle II, we revisit this observable in this paper. Firstly, we reproduce the known CP asymmetry due to $K^0 -\bar{K}^0$ mixing by means of the reciprocal basis, which is convenient when a $K_{S(L)}$ is involved in the final state. As the $K\pi$ tensor form factor plays a crucial role in generating a non-zero direct CP asymmetry that can arise only from the interference of vector and tensor operators, we then present a dispersive representation of this form factor, with its phase obtained in the context of chiral theory with resonances, which fulfills the requirements of unitarity and analyticity. Finally, the $\tau\to K_S\pi\nu_\tau$ decays are analyzed both within a model-independent low-energy effective theory framework and in a scalar leptoquark scenario. It is observed that the CP anomaly can be accommodated in the model-independent framework, even at the $1\sigma$ level, together with the constraint from the branching ratio of $\tau^-\to K_S\pi^-\nu_\tau$ decay; it can be, however, marginally reconciled only at the $2\sigma$ level, due to the specific relation between the scalar and tensor operators in the scalar leptoquark scenario. Once the combined constraints from the branching ratio and the decay spectrum of this decay are taken into account, these possibilities are however both excluded, even without exploiting further the stronger bounds from the (semi-)leptonic kaon decays under the assumption of lepton-flavour universality, as well as from the neutron electric dipole moment and $D-\bar{D}$ mixing under the assumption of $SU(2)$ invariance of the weak interactions.

Hard processes in small systems

These proceedings from the Quark Matter 2017 conference give an overview of the latest experimental results on hard processes in small collision systems at RHIC and the LHC, discuss their implications, and consider several prospects for future measurements.

Cometary Isotopic Measurements

Isotopic ratios in comets provide keys for the understanding of the origin of cometary material, and the physical and chemical conditions in the early Solar Nebula. We review here measurements acquired on the D/H, 14N/15N, 16O/18O, 12C/13C, and 32S/34S ratios in cometary grains and gases, and discuss their cosmogonic implications. The review includes analyses of potential cometary material available in collections on Earth, recent measurements achieved with the Herschel Space Observatory, large optical telescopes, and Rosetta, as well as recent results obtained from models of chemical-dynamical deuterium fractionation in the early solar nebula. Prospects for future measurements are presented.

CHARMONIUM PRODUCTION IN Pb–Pb COLLISIONS AT ALICE: FROM SUPPRESSION TO REGENERATION?

Heavy quarkonium states are considered as one of the key observables for the study of the phase transition from a system made of hadrons towards a Quark–Gluon Plasma (QGP). In the last 25 years, experiments at CERN and Brookhaven have studied collisions of heavy ions looking for a suppression of charmonia/bottomonia, considered as a signature of the phase transition. After an introduction to the main concepts behind these studies and a short review of the SPS and RHIC results, I will describe the results obtained in Pb – Pb collisions by the ALICE experiment at the LHC. The ALICE findings will be critically compared to those of lower energy experiments, to CMS results, and to model calculations. The large cross-sections for heavy-quark production at LHC energies are expected to induce a novel production mechanism for charmonia in heavy-ion collisions, related to a recombination of [Formula: see text] pairs along the history of the collision and/or at hadronization. The occurrence of such a process at the LHC will be discussed. Finally, prospects for future measurements will be shortly addressed.

Results from the Borexino Solar Neutrino Experiment

Borexino is a low-background liquid scintillation detector currently acquiring solar and terrestrial neutrino data at the Gran Sasso underground laboratory in Italy. Since the start of operations in 2007, Borexino has produced measurements of 7Be, 8B, and pep solar neutrinos, as well as measurements of terrestrial and long-baseline reactor antineutrinos. The measurements were made possible by the development of low-background scintillator spectroscopy that enabled direct detection of sub-MeV solar neutrinos. The general design features of the detector are described together with current results and prospects for future measurements.

Solar and Terrestrial Neutrino Results from Borexino

Borexino is a low background liquid scintillation detector currently acquiring solar and terrestrial neutrino data at the LNGS underground laboratory in Italy. In the three years since the start of operations in 2007, Borexino has produced measurements of 7Be and 8B solar neutrinos, as well as measurements of terrestrial and long-baseline reactor anti-neutrinos. The measurements of sub-MeV neutrinos were possible owing to a breakthrough in low background methods. Current results and prospects for future measurements with lower background and higher accuracy are discussed in the context of exploring the transition from vacuum to matter enhanced neutrino oscillations.

Pentaquark searches at HERA

Searches and measurements of strange and charmed pentaquarks by the H1 and ZEUS experiments at the HERA ep collider are presented. The analyses were performed in the central region of the laboratory frame of inclusive deep-inelastic scattering at a center-of-mass energy of 300-318 GeV with the full HERA I luminosity. Some conclusions and prospects for future measurements with HERA II are also presented.

IMPLICATIONS FROM CURRENT DATA FOR NEUTRINO MASSES AND MIXING, AND SOME SENSITIVITIES OF FUTURE EXPERIMENTS

Current constraints on neutrino mass and mixing parameters are briefly reviewed, and the prospects for future measurements in long-baseline neutrino experiments are discussed. Parameter degeneracies are a generic problem in the three–neutrino analysis of long-baseline neutrino appearance measurements, and can lead to different inferred values for the neutrino mixing angle θ13 and often mix CP violating and CP conserving solutions. Possible experimental strategies for reducing or eliminating such degeneracies and/or the CP confusion are discussed.

Deeply virtual compton scattering at HERMES: present and future

The beam-helicity asymmetry in hard electroproduction of photons has been measured for the first time by the HERMES experiment using the HERA 27.6 GeV longitudinally polarized positron beam and an unpolarized hydrogen target. The observed asymmetry is attributed to the interference of the Bethe-Heitler (BH) and Deeply Virtual Compton Scattering (DVCS) processes. Prospects for future measurements of DVCS at HERMES are studied using simple models for parameterizations of generalized parton distributions (GPDs).

STUDY OF TRILINEAR GAUGE-BOSON COUPLINGS AT THE TEVATRON COLLIDER

▪ Abstract We review studies of the trilinear gauge-boson couplings at the Tevatron proton-antiproton collider from data collected by the CDF and DØ collaborations during the period 1992–1996. The gauge-boson couplings are a fundamental prediction of the standard model, resulting from the non-Abelian nature of the theory. Therefore, experimental tests of the couplings are of foremost importance. We introduce the experimental results by reviewing the effective Lagrangian formalism, the indirect constraints on the couplings from low-energy experiments, and the expected values of the couplings in theories beyond the standard model. Finally, we consider the prospects for future measurements.

Tests of parton distribution functions at the Tevatron Collider

Tevatron Collider experiments (CDF and DO) have unique advantages in testing parton distribution functions. Because hadrons are used on both sides of the initial state, these experiments have difficulty in isolating the contribution from each type of parton, but offer unique sensitivity to the gluon structure function, a large renge of Q 2 , and a wide variety of probes (jet, γ, W, Z , and b -quark). Recent results and prospects for future measurements are presented.

A search for the Sunyaev-Zel'dovich effect at lambda = 3 millimeters

view Abstract Citations (15) References (22) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A Search for the Sunyaev-Zel'dovich Effect at lambda = 3 Millimeters Radford, Simon J. E. ; Boynton, Paul E. ; Ulich, Bobby L. ; Partridge, R. Bruce ; Schommer, Robert A. ; Stark, Antony A. ; Wilson, Robert W. ; Murray, Stephen S. Abstract Using both drift scan and source tracking observations, a search was made for the Sunyaev-Zel'dovich effect in seven clusters of galaxies at a wavelength of 3 mm using the National Radio Astronomy Observatory 12 m (formerly 11 m) telescope on Kitt Peak and the AT&T Bell Laboratories 7 m telescope at Crawford Hill. The measurements set upper limits on the magnitude of the Sunyaev-Zel'dovich effect that are consistent with all previous, longer wavelength, searches. A method for comparison of observations is introduced that is independent of the details of the measurement and only weakly dependent on the intracluster gas model. The consistency of existing observations and the prospects for future measurements are discussed. Publication: The Astrophysical Journal Pub Date: January 1986 DOI: 10.1086/163790 Bibcode: 1986ApJ...300..159R Keywords: Background Radiation; Compton Effect; Cosmic Rays; Galactic Clusters; Microwave Emission; Millimeter Waves; Radio Astronomy; Photons; Radio Galaxies; Astronomy; GALAXIES: CLUSTERING; RADIATION MECHANISMS; RADIO SOURCES: GENERAL full text sources ADS | data products SIMBAD (6) NED (4)