We present a feasibility study of a simultaneous sub-percent extraction of the weak charge and the weak radius of the ${}^{12}$C nucleus using parity-violating electron scattering, based on a largely model-independent assessment of the uncertainties.
The corresponding measurement is considered to be carried out at the future MESA facility in Mainz with $E_{rm beam} = 155$ MeV. We find that a combination of a $0.3%$ precise measurement of the parity-violating asymmetry at forward angles with a $10%$ measurement at backward angles will allow to determine the weak charge and the weak radius of ${}^{12}$C with $0.4%$ and $0.5%$ precision, respectively. These values could be improved to $0.3%$ and $0.2%$ for a $3%$ backward measurement. This experimental program will have impact on precision low-energy tests in the electroweak sector and nuclear structure.
We present the fully up-to-date calculation of the $gamma Z$-box correction which needs to be taken into account to determine the weak mixing angle at low energies from parity-violating electron proton scattering. We make use of neutrino and antineut
rino inclusive scattering data to predict the parity-violating structure function $F_3^{gamma Z}$ by isospin symmetry. Our new analysis confirms previous results for the axial contribution to the $gamma Z$-box graph, and reduces the uncertainty by a factor of~2. In addition, we note that the presence of parity-violating photon-hadron interactions induces an additional contribution via $F_3^{gamma gamma}$. Using experimental and theoretical constraints on the nucleon anapole moment we are able to estimate the uncertainty associated with this contribution. We point out that future measurements are expected to significantly reduce this latter uncertainty.
Sunyaev-Zeldovich (SZ) effects were first proposed in the 1970s as tools to identify the X-ray emitting hot gas inside massive clusters of galaxies and obtain their velocities relative to the cosmic microwave background (CMB). Yet it is only within t
he last decade that they have begun to significantly impact astronomical research. Thanks to the rapid developments in CMB instrumentation, measurement of the dominant thermal signature of the SZ effects has become a routine tool to find and characterize large samples of galaxy clusters and to seek deeper understanding of several important astrophysical processes via high-resolution imaging studies of many targets. With the notable exception of the Planck satellite and a few combinations of ground-based observatories, much of this SZ revolution has happened in the photometric mode, where observations are made at one or two frequencies in the millimeter regime to maximize the cluster detection significance and minimize the foregrounds. Still, there is much more to learn from detailed and systematic analyses of the SZ spectra across multiple wavelengths, specifically in the submillimeter (>300 GHz) domain. The goal of this Science White Paper is to highlight this particular aspect of SZ research, point out what new and potentially groundbreaking insights can be obtained from these studies, and emphasize why the coming decade can be a golden era for SZ spectral measurements.
We determine the charm quark mass ${hat m}_c({hat m}_c)$ from QCD sum rules of moments of the vector current correlator calculated in perturbative QCD. Only experimental data for the charm resonances below the continuum threshold are needed in our ap
proach, while the continuum contribution is determined by requiring self-consistency between various sum rules, including the one for the zeroth moment. Existing data from the continuum region can then be used to bound the theoretical error. Our result is ${hat m}_c({hat m}_c) = 1272 pm 8$ MeV for $hatalpha_s(M_Z) = 0.1182$. Special attention is given to the question how to quantify and justify the uncertainty.
Galaxy cluster merger shocks are the main agent for the thermalization of the intracluster medium and the energization of cosmic ray particles in it. Shock propagation changes the state of the tenuous intracluster plasma, and the corresponding signal
variations are measurable with the current generation of X-ray and Sunyaev-Zeldovich (SZ) effect instruments. Additionally, non-thermal electrons (re-)energized by the shocks sometimes give rise to extended and luminous synchrotron sources known as radio relics, which are prominent indicators of shocks propagating roughly in the plane of the sky. In this short review, we discuss how the joint modeling of the non-thermal and thermal signal variations across radio relic shock fronts is helping to advance our knowledge of the gas thermodynamical properties and magnetic field strengths in the cluster outskirts. We describe the first use of the SZ effect to measure the Mach numbers of relic shocks, for both the nearest (Coma) and the farthest (El Gordo) clusters with known radio relics.
In this paper, we present preliminary results of the determination of the charm quark mass $hat{m}_c$ from QCD sum rules of moments of the vector current correlator calculated in perturbative QCD at ${cal O} (hat alpha_s^3)$. Self-consistency between
two different sum rules allow to determine the continuum contribution to the moments without requiring experimental input, except for the charm resonances below the continuum threshold. The existing experimental data from the continuum region is used, then, to confront the theoretical determination and reassess the theoretic uncertainty.
We present ALMA measurements of a merger shock using the thermal Sunyaev-Zeldovich (SZ) effect signal, at the location of a radio relic in the famous El Gordo galaxy cluster at $z approx 0.9$. Multi-wavelength analysis in combination with the archiva
l Chandra data and a high-resolution radio image provides a consistent picture of the thermal and non-thermal signal variation across the shock front and helps to put robust constraints on the shock Mach number as well as the relic magnetic field. We employ a Bayesian analysis technique for modeling the SZ and X-ray data self-consistently, illustrating respective parameter degeneracies. Combined results indicate a shock with Mach number ${cal M} = 2.4^{+1.3}_{-0.6}$, which in turn suggests a high value of the magnetic field (of the order of $4-10 ~mu$G) to account for the observed relic width at 2 GHz. At roughly half the current age of the universe, this is the highest-redshift direct detection of a cluster shock to date, and one of the first instances of an ALMA-SZ observation in a galaxy cluster. It shows the tremendous potential for future ALMA-SZ observations to detect merger shocks and other cluster substructures out to the highest redshifts.
(Abridged) Radio relics in galaxy clusters are believed to be associated with powerful shock fronts that originate during cluster mergers, and are a testbed for the acceleration of relativistic particles in the intracluster medium. Recently, radio re
lic observations have pushed into the cm-wavelength domain (1-30 GHz) where a break from the standard synchrotron power-law spectrum has been found, most noticeably in the famous Sausage relic. In this paper, we point to an important effect that has been ignored or considered insignificant while interpreting these new high-frequency radio data, namely the contamination due to the Sunyaev-Zeldovich (SZ) effect that changes the observed synchrotron flux. Even though the radio relics reside in the cluster outskirts, the shock-driven pressure boost increases the SZ signal locally by roughly an order of magnitude. The resulting flux contamination for some well-known relics are non-negligible already at 10 GHz, and at 30 GHz the observed synchrotron fluxes can be diminished by a factor of several from their true values. Interferometric observations are not immune to this contamination, since the change in the SZ signal occurs roughly at the same length scale as the synchrotron emission, although there the flux loss is less severe than single-dish observations. We present a simple analytical approximation for the synchrotron-to-SZ flux ratio, based on a theoretical radio relic model that connects the non-thermal emission to the thermal gas properties, and show that by measuring this ratio one can potentially estimate the relic magnetic fields or the particle acceleration efficiency.
We classify the quantum numbers of the extra $U(1)$ symmetries contained in $E_6$. In particular, we categorize the cases with rational charges and present the full list of models which arise from the chains of the maximal subgroups of $E_6$. As an a
pplication, the classification allows us to determine all embeddings of the Standard Model fermions in all possible decompositions of the fundamental representation of $E_6$ under its maximal subgroups. From this we find alternative chains of subgroups for Grand Unified Theories. We show how many of the known models including some new ones appear in alternative breaking patterns. We also use low energy constraints coming from parity-violating asymmetry measurements and atomic parity non-conservation to set limits on the $E_6$ motivated parameter space for a $Z$ boson mass of~1.2~TeV. We include projected limits for the present and upcoming QWEAK, MOLLER and SOLID experiments.
We use sampling techniques to find robust constraints on the masses of a possible fourth sequential fermion generation from electroweak oblique variables. We find that in the case of a light (115 GeV) Higgs from a single electroweak symmetry breaking
doublet, inverted mass hierarchies are possible for both quarks and leptons, but a mass splitting more than M(W) in the quark sector is unlikely. We also find constraints in the case of a heavy (600 GeV) Higgs in a single doublet model. As recent data from the Large Hadron Collider hints at the existence of a resonance at 124.5 GeV and a single Higgs doublet at that mass is inconsistent with a fourth fermion generation, we examine a type II two Higgs doublet model. In this model, there are ranges of parameter space where the Higgs sector can potentially counteract the effects of the fourth generation. Even so, we find that such scenarios produce qualitatively similar fermion mass distributions.
