Precision Physics Research Articles

IR-Improved Amplitude-Based Resummation in Quantum Field Theory: New Results and New Issues

With the advancement of strategies for the precision physics programs for the HL-LHC, FCC-ee, FCC-hh, ILC, CLIC, CEPC, and CPPC, the need for proper control of the attendant theoretical precision tags is manifest. We discuss the role that amplitude-based resummation may play in this regard with examples from the LHC, the proposed new colliders and quantum gravity.

Parallelism measurement method for nontransparent flat parts.

Nontransparent flat parts with weak rigidity are widely used in precision physics experiments, aerospace, and other fields in which parallelism is required. However, existing methods cannot meet requirements due to the limitation of measurement size and accuracy. This paper proposes a new method for measuring parallelism of nontransparent flat parts with high accuracy and then builds a submicrometer-level parallelism measuring system. The 3D model of the whole part is reconstructed by thickness and flatness, which are measured respectively. Subsequently, parallelism is evaluated by the principle of minimum directional zone. The method is verified by an experiment with a thin copper substrate sized ⊘200mm×2.48mm on the parallelism measuring system. The experiment result shows that the part's parallelism is 7.41 µm, and the expanded uncertainty of parallelism measurement system is 0.34 µm, k=2.

Perturbative hysteresis and emergent resummation scales

We investigate hysteresis effects in the perturbative solution of renormalization group equations (RGEs). We present examples for the QCD running coupling and proton's parton distribution functions (PDFs), relevant to precision physics at the Large Hadron Collider and future collider experiments. We propose the use of resummation scales to take into account the theoretical uncertainties from the solution of the RGEs. As a case study, we consider the ${F}_{2}$ structure function in a region relevant to the extraction of PDFs.

Flavour anomalies and the muon g − 2 from feebly interacting particles

We perform a phenomenological analysis of simplified models of light, feebly interacting particles (FIPs) that can provide a combined explanation of the anomalies in b → sl+l− transitions at LHCb and the anomalous magnetic moment of the muon. Different scenarios are categorised according to the explicit momentum dependence of the FIP coupling to the b−s and μ−μ vector currents and they are subject to several constraints from flavour and precision physics. We show that viable combined solutions to the muon g − 2 and flavour anomalies exist with the exchange of a vector FIP with mass larger than 4 GeV. Interestingly, the LHC has the potential to probe this region of the parameter space by increasing the precision of the Z → 4μ cross-section measurement. Conversely, we find that solutions based on the exchange of a lighter vector, in the mV< 1 GeV range, are essentially excluded by a combination of B → K+ invisible and W-decay precision bounds.

Tera- Z stage at future colliders and light composite axionlike particles

The Tera-Z phase of future $e^+ e^-$ colliders, FCC-ee and CepC, is a goldmine for exploring $Z$ portal physics. We focus on axion-like particles (ALPs) that can be produced via $Z$ decays with a monochromatic photon. As a template model, we consider composite Higgs models with a light pseudo-scalar that couples through the Wess-Zumino-Witten term to the electroweak gauge bosons. For both photophilic and photophobic cases, we show that the Tera-Z can probe composite scales up to $100$s of TeV, well beyond the capability of the LHC and current precision physics. Our results also apply to generic ALPs and, in particular, severely constrain models that explain the muon $g-2$ anomaly.

ESTIMACIÓN DEL FLUJO DE MUONES EN EL LABORATORIO SUBTERRÁNEO ANDES

The ANDES Underground Laboratory is being planned and designed to be one of the largest and most shielded laboratories in the Southern Hemisphere, which will be located in the Andes Range, in the area of the current Paso AguaNegra that connects the provinces of San Juan (Argentina) and Elqui (Chile). The diversity of experiments that are being planned, including experiments for the direct and indirect search of dark matter and neutrino precision physics, requires a precise knowledge of the flux of high-energy atmospheric muons within the laboratory. These are produced during the interaction of astroparticles with energies between 1012and 1018eV denominated of high and ultra-high energy with the Earth’s atmosphere. In the high-energy component, muons with energies of tens of TeV can be found, capable of passing through thousands of meters of rock. Previous estimates made from reasonable assumptions about the type of rock expected in the area showed that the expected muon flux was compatible with other underground laboratories at an equivalent depth. In this work, extensive atmospheric showers flux simulations were performed at the laboratory site. Afterwards, there was a selection of those muons with sufficient energy to reach the laboratory-based on their angle of incidence and the height at which they enter the mountain. Then a transfer function was modeled using the new geological studies currently available that allow us to have a detailed model of the rock distribution inside the mountain. Finally, the interaction of these muons with the different types of rock was calculated numerically along their way to the laboratory using the continuous slowdown approximation, thus obtaining that the expected muon flux within the laboratory is 1,47±0,02 day−1m−2sr−1

Adequacy of Effective Born for electroweak effects and TauSpinner algorithms for high energy physics simulated samples

Matching and comparing the measurements of past and future experiments call for consistency checks of electroweak (EW) calculations used for their interpretation. On the other hand, new calculation schemes of the field theory can be beneficial for precision, even if they may obscure comparisons with earlier results. Over the years, concepts of Improved Born, Effective Born, as well as of effective couplings, in particular of sin ^2theta _W^{{textit{eff}}} mixing angle for EW interactions, have evolved. In our discussion, we use four versions of DIZET EW library for phenomenology of practically all HEP accelerator experiments over the last 30 years. We rely on the codes published and archived with the KKMC Monte Carlo program for e^+e^- rightarrow f {bar{f}} n(gamma ) and available for the TauSpinner as well. TauSpinner re-weighs generated events for introduction of EW effects. To this end, DIZET is first invoked, and its results are stored in data file and later used. Documentation of TauSpinner upgrade, to version 2.1.0, and that of its new arrangement for semi-automated benchmark plots are provided. In our paper, focus is placed on the numerical results, on the different approximations introduced in Improved Born to obtain Effective Born, which is simpler for applications of strong or QED processes in pp or e^+e^- colliders. The tau lepton polarization P_{tau }, forward–backward asymmetry A_{{textit{FB}}} and parton-level total cross section sigma ^{{textit{tot}}} are used to monitor the size of EW effects and effective sin ^2theta _W^{{textit{eff}}} picture limitations for precision physics. Collected results include: (i) Effective Born approximations and sin ^2theta _W^{{textit{eff}}}, (ii) differences between versions of EW libraries and (iii) parametric uncertainties due to, for example, m_t or Delta alpha _h^{(5)}(s). These results can be considered as benchmarks and also allow to evaluate the adequacy of Effective Born with respect to Improved Born. Definitions are addressed too.

First Results from an Axion Haloscope at CAPP around 10.7 μeV.

The Center for Axion and Precision Physics Research at the Institute for Basic Science is searching for axion dark matter using ultralow temperature microwave resonators. We report the exclusion of the axion mass range 10.7126-10.7186 μeV with near Kim-Shifman-Vainshtein-Zakharov (KSVZ) coupling sensitivity and the range 10.16-11.37 μeV with about 9 times larger coupling at 90%confidence level. This is the first axion search result in these ranges. It is also the first with a resonator physical temperature of less than 40mK.

Two paths towards precision at a very high energy lepton collider

We illustrate the potential of a very high energy lepton collider (from 10 to 30 TeV center of mass energy) to explore new physics indirectly in the vector boson fusion double Higgs production process and in direct diboson production at high energy. Double Higgs production is found to be sensitive to the anomalous Higgs trilinear coupling at the percent level, and to the Higgs compositeness ξ parameter at the per mille or sub-per mille level thanks to the measurement of the cross-section in the di-Higgs high invariant mass tail. High energy diboson (and tri-boson) production is sensitive to Higgs-lepton contact interaction operators at a scale of several tens or hundred TeV, corresponding to a reach on the Higgs compositeness scale well above the one of any other future collider project currently under discussion. This result follows from the unique capability of the very high energy lepton collider to measure Electroweak cross-sections at 10 TeV energy or more, where the effect of new physics at even higher energy is amplified. The general lesson is that the standard path towards precision physics, based on measurements of high-statistics processes such as single and double Higgs production, is accompanied at the very high energy lepton collider by a second strategy based on measurements at the highest available energy.

Scalar dark matter candidates revisited

We revisit the possibility of light scalar dark matter, in the MeV to GeV mass bracket and coupled to electrons through fermion or vector mediators, in light of significant experimental and observational advances that probe new physics below the GeV-scale. We establish new limits from electron colliders and fixed-target beams, and derive the strength of loop-induced processes that are probed by precision physics, among other laboratory probes. In addition, we compute the cooling bound from SN1987A, consider self-scattering, structure formation, and cosmological constraints as well as the limits from dark matter-electron scattering in direct detection experiments. We then show that the combination of constraints largely excludes the possibility that the galactic annihilation of these particles may explain the long-standing INTEGRAL excess of 511 keV photons as observed in the galactic bulge. As caveat to these conclusions we identify the resonant annihilation regime where the vector mediator goes nearly on-shell.

Light neutral meson production in heavy ion collisions with ALICE in the era of precision physics at the LHC

The production of light neutral mesons in AA collisions probes the physics of the Quark-Gluon Plasma (QGP), which is formed in heavy-ion collisions at the LHC. More specifically, the centrality dependent neutral meson spectra in AA collisions compared to its spectra in minimum-bias pp collisions, scaled with the number of hard collisions, provides information on the energy loss of partons traversing the QGP. The measurement allows to test with high precision the predictions of theoretical model calculations. In addition, the decay of the π0 and η mesons are the dominant back- grounds for all direct photon measurements. Therefore, pushing the limits of the precision of neutral meson production is key to learning about the temperature and space-time evolution of the QGP.In the ALICE experiment neutral mesons can be detected via their decay into two photons. The latter can be reconstructed using the two calorimeters EMCal and PHOS or via conversions in the detector material. The excellent momentum resolution of the conversion photons down to very low pT and the high reconstruction efficiency and triggering capability of calorimeters at high pT, allow us to measure the pT dependent invariant yield of light neutral mesons over a wide kinematic range.Combining state-of-the-art reconstruction techniques with the high statistics delivered by the LHC in Run 2 gives us the opportunity to enhance the precision of our measurements. In these proceedings, new ALICE run 2 preliminary results for neutral meson production in pp and Pb–Pb collisions at LHC energies are presented.

Magnon-driven dynamics of a hybrid system excited with ultrafast optical pulses

The potential of photon-magnon hybrid systems as building blocks for quantum information science has been widely demonstrated, and it is still the focus of much research. We leverage the strengths of this unique heterogeneous physical system in the field of precision physics beyond the standard model, where the sensitivity to the so-called “invisibles” is currently being boosted by quantum technologies. Here, we demonstrate that quanta of spin waves, induced by effective magnetic fields, can be detected in a large frequency band using a hybrid system as transducer. This result can be applied to the search of cosmological signals related, for example, to cold Dark Matter, which may directly interact with magnons. Our model of the transducer is based on a second-quantisation two-oscillators hybrid system, it matches the observations, and can be easily extended to thoroughly describe future large-scale ferromagnetic haloscopes.

Collinear apparatus for laser spectroscopy overcomes systematic uncertainty limits

A collinear laser spectroscopy apparatus for high-voltage metrology and precision physics experiments is developed.

Machine-learning nonstationary noise out of gravitational-wave detectors

Signal extraction out of background noise is a common challenge in high precision physics experiments, where the measurement output is often a continuous data stream. To improve the signal to noise ratio of the detection, witness sensors are often used to independently measure background noises and subtract them from the main signal. If the noise coupling is linear and stationary, optimal techniques already exist and are routinely implemented in many experiments. However, when the noise coupling is non-stationary, linear techniques often fail or are sub-optimal. Inspired by the properties of the background noise in gravitational wave detectors, this work develops a novel algorithm to efficiently characterize and remove non-stationary noise couplings, provided there exist witnesses of the noise source and of the modulation. In this work, the algorithm is described in its most general formulation, and its efficiency is demonstrated with examples from the data of the Advanced LIGO gravitational wave observatory, where we could obtain an improvement of the detector gravitational wave reach without introducing any bias on the source parameter estimation.

Design, construction, and operation of an 18 T 70 mm no-insulation (RE)Ba2Cu3O7−x magnet for an axion haloscope experiment

We report the design, construction, and operation results of an 18 T 70 mm cold-bore high temperature superconductor (HTS) no-insulation (NI) magnet, which is developed for an axion haloscope experiment. The magnet consists of 44 double-pancake coils wound with multi-width and multi-thickness REBa2Cu3O7-x (RE = rare earth) tapes. Owing to the NI feature, the magnet is highly compact; is 162 mm in outer diameter and 476 mm tall; and provides an environment of 0.22 T2 m3 within the cold-bore target space of 66 mm in diameter and 200 mm in length. After an initial performance test at SuNAM Co. Ltd., the magnet was installed at the Center for Axion and Precision Physics Research (CAPP) of the Institute for Basic Science in Daejeon, South Korea, in August 2017. The magnet has been successfully operating at the CAPP since then, except for maintenance in October 2018. The magnet may represent the first high field HTS user magnet that experienced long-term operation of over one year.

Neutrino Long-Baseline Experiments and Nuclear Physics

The Standard Model (SM) of particle physics has had its triumphant moment when in 2012 the Higgs particle was discovered at the Large Hadron Collider (LHC). Since then the research program at CERN has focused on finding new physics beyond the standard model (BSM). Since even the recent experimental runs did not yield any obvious new particles or phenomena the emphasis now is on precision physics. One prerequisite for these BSM precision studies is the remarkable beam precision and stability at LHC. The beam energy is known to better than 0.1% and its changes during a run are within about 0.02%. Enormous technical expertise, equipment, and work went into reaching this accuracy. Up to today, however, no sign of BSM physics has been sighted.

The Gauge-Higgs legacy of the LHC run II

We present a global analysis of the Higgs and electroweak sector based on LHC Run II and electroweak precision observables. We show which measurements provide the leading constraints on Higgs-related operators, and how the achieved LHC precision makes it necessary to combine rate measurements with electroweak precision observables. The SFitter framework allows us to include kinematic distributions beyond pre-defined ATLAS and CMS observables, independently study correlations, and avoid Gaussian assumptions for theory uncertainties. These Run II results are a step towards a precision physics program at the LHC, interpreted in terms of effective operators.

Toward a First-Principles Calculation of Electroweak Box Diagrams.

We derive a Feynman-Hellmann theorem relating the second-order nucleon energy shift resulting from the introduction of periodic source terms of electromagnetic and isovector axial currents to the parity-odd nucleon structure function F_{3}^{N}. It is a crucial ingredient in the theoretical study of the γW and γZ box diagrams that are known to suffer from large hadronic uncertainties. We demonstrate that for a given Q^{2} one only needs to compute a small number of energy shifts in order to obtain the required inputs for the box diagrams. Future lattice calculations based on this approach may shed new light on various topics in precision physics including the refined determination of the Cabibbo-Kobayashi-Maskawa matrix elements and the weak mixing angle.

Electroweak physics at CEPC

The Circular Electron–Positron Collider (CEPC) project aims to build a Circular Electron–Positron Collider capable of precision physics measurements at center-of-mass energies ranging from 90 GeV to 240 GeV. The CEPC will have a total circumference of at least one hundred kilometers and at least two interaction points. In its 10 years operation at 240 GeV, it will collect more than one million Higgs events. CEPC will also run at the [Formula: see text] pole for two years, producing more than 300 billion [Formula: see text] bosons in two years. It will also collect data around the [Formula: see text] threshold for one year, in order to perform the [Formula: see text] boson mass measurement with high precision. These datasets will boost the precision of electroweak measurements by orders of magnitude. An overview is presented of the potential of CEPC to advance precision studies of electroweak physics with an emphasis on the opportunities in [Formula: see text] and [Formula: see text] physics.

Systematic studies of exact O(α2L) CEEX EW corrections in a hadronic MC for precision Z/γ* physics at LHC energies

With an eye toward the precision physics of the LHC, such as the recent measurement of $M_W$ by the ATLAS Collaboration, we present here systematic studies relevant to the assessment of the expected size of multiple photon radiative effects in heavy gauge boson production with decay to charged lepton pairs. We use the new version 4.22 of ${\cal KK}$MC-hh so that we have CEEX EW exact ${\cal O}(\alpha^2 L)$ corrections in a hadronic MC and control over the corresponding EW initial-final interference (IFI) effects as well. In this way, we illustrate the interplay between cuts of the type used in the measurement of $M_W$ at the LHC and the sizes of the expected responses of the attendant higher order corrections. We find that there are per cent to per mille level effects in the initial-state radiation, fractional per mille level effects in the IFI and per mille level effects in the over-all ${\cal O}(\alpha^2 L)$ corrections that any treatment of EW corrections at the per mille level should consider. Our results have direct applicability to current LHC experimental data analyses.