Low-energy Hadron Research Articles

Microbunched Electron Cooling for High-Energy Hadron Beams

Electron and stochastic cooling are proven methods for cooling low-energy hadron beams, but at present there is no way of cooling hadrons as they near the TeV scale. In the 1980s, Derbenev suggested that electron instabilities, such as free-electron lasers, could create collective space charge fields strong enough to correct the hadron energies. This Letter presents a variation on Derbenev's electron cooling scheme using the microbunching instability as the amplifier. The large bandwidth of the instability allows for faster cooling of high-density beams. A simple analytical model illustrates the cooling mechanism, and simulations show cooling rates for realistic parameters of the Large Hadron Collider.

Synchrotron oscillation effects for spin resonances driven by a localized oscillating rf magnetic field

I derive a generalized tune modulation parameter, to take into account time-of-arrival effects for synchrotron tune modulation of spin resonances driven by a localized rf solenoid or rf dipole, i.e. a time-dependent oscillating magnetic field. I show that the extra effects are negligible for high energy electron storage rings, but they might not be negligible for low or medium energy hadron storage rings. I show that alternative interpretations are possible for some previously published data of bunched stored polarized hadron beams. I suggest benchmark tests for new experimental measurements.

HEAVY HADRON SPECTROSCOPY: A QUARK MODEL PERSPECTIVE

We present recent results of hadron spectroscopy and hadron–hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher-order Fock space components in the hadron spectra and the connection of this extension with the hadron–hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about the low-energy realization of the theory.

The influence of low energy hadron interaction models in CORSIKA code on atmospheric ionization due to heavy nuclei

The largest uncertainties in a numerical simulation of cosmic ray induced atmospheric cascade are due to hadron interaction models. The influence of low energy hadron interaction models in CORSIKA code on longitudinal cascade development is important. It results longitudinal cascade development, respectively energy deposit and atmospheric ionization by secondary particles. In this work are presented simulations with CORSIKA 6.990 code using GHEISHA 2000, FLUKA 2011 and QGSJET II hadron generators. The energy deposit in the atmosphere by various nuclei, namely Helium, Oxygen and Iron is calculated. The ion pair production in the atmosphere and the impact of the different shower components, precisely the electromagnetic, muon and hadron is estimated according the used hadron generators. The yield function Y for total ionization is compared for various cases. The observed differences and applications are discussed.

Application of Chiral Resonance Lagrangian Theories to the Muon $g-2$

We think that phenomenological resonance Lagrangian models, constrained by global fits from low energy hadron reaction data, can help to improve muon g-2 predictions. The main issue are those contributions which cannot be calculated by perturbative means: the hadronic vacuum polarization (HVP) effects and the hadronic light--by--light (HLbL) scattering contribution. I review recent progress in the evaluation of the HVP contribution within the broken Hidden Local Symmetry (HLS) framework, worked out in collaboration with M. Benayoun, P. David and L. DelBuono. Our HLS driven estimate reads a_mu (LO had)=(688.60+\-4.24) 10^{-10} and we find a_mu (theory)= (11 659 177.65 +/- 5.76) 10^{-10}.

Heavy hadron spectroscopy: A quark model perspective

Abstract We present recent results of hadron spectroscopy and hadron–hadron interaction from the perspective of constituent quark models. We pay special attention to the role played by higher order Fock space components in the hadron spectra and the connection of this extension with the hadron–hadron interaction. The main goal of our description is to obtain a coherent understanding of the low-energy hadron phenomenology without enforcing any particular model, to constrain its characteristics and learn about low-energy realization of the theory.

On a microscopic representation of space-time

We start from a noncompact Lie algebra isomorphic to the Dirac algebra and relate this Lie algebra in a brief review to low energy hadron physics described by the compact group SU(4). This step permits an overall physical identification of the operator actions. Then we discuss the geometrical origin of this noncompact Lie algebra and 'reduce' the geometry in order to introduce in each of these steps coordinate definitions which can be related to an algebraic representation in terms of the spontaneous symmetry breakdown along the Lie algebra chain su*(4) $\longrightarrow$ usp(4) $\longrightarrow$ su(2)$\times$u(1). Standard techniques of Lie algebra decomposition(s) as well as the (physical) operator identification give rise to interesting physical aspects and lead to a rank-1 Riemannian space which provides an analytic representation and leads to a 5-dimensional hyperbolic space $H_{5}$ with SO(5,1) isometries. The action of the (compact) symplectic group decomposes this (globally) hyperbolic space into $H_{2}\oplus H_{3}$ with SO(2,1) and SO(3,1) isometries, respectively, which we relate to electromagnetic (dynamically broken SU(2) isospin) and Lorentz transformations. Last not least, we attribute this symmetry pattern to the algebraic representation of a projective geometry over the division algebra $H$ and subsequent coordinate restrictions.

Consistency tests of Ampcalculator and chiral amplitudes in SU(3) Chiral Perturbation Theory: A tutorial-based approach

Ampcalculator is a Mathematica based program that was made publicly available some time ago by Unterdorfer and Ecker. It enables the user to compute several processes at one-loop (upto $O(p^4)$) in SU(3) chiral perturbation theory. They include computing matrix elements and form factors for strong and non-leptonic weak processes with at most six external states. It was used to compute some novel processes and was tested against well-known results by the original authors. Here we present the results of several thorough checks of the package. Exhaustive checks performed by the original authors are not publicly available, and hence the present effort. Some new results are obtained from the software especially in the kaon odd-intrinsic parity non-leptonic decay sector involving the coupling $G_{27}$. Another illustrative set of amplitudes at tree level we provide is in the context of $\tau$-decays with several mesons including quark mass effects, of use to the BELLE experiment. All eight meson-meson scattering amplitudes have been checked. Kaon-Compton amplitude has been checked and a minor error in published results has been pointed out. This exercise is a tutorial based one, wherein several input and output notebooks are also being made available as ancillary files on the arXiv. Some of the additional notebooks we provide contain explicit expressions that we have used for comparison with established results. The purpose is to encourage users to apply the software to suit their specific needs. An automatic amplitude generator of this type can provide error-free outputs that could be used as inputs for further simplification, and used in varied scenarios such as applications of chiral perturbation theory at finite temperature, density and volume. This can also be used by students as a learning aid in low-energy hadron dynamics.

Quark-model study of the hadron structure and the hadron-hadron interaction

Recent results of hadron spectroscopy and hadron-hadron interaction within a quark model framework are reviewed. Higher order Fock space components are considered based on new experimental data on low-energy hadron phenomenology. The purpose of this study is to obtain a coherent description of the low-energy hadron phenomenology to constrain QCD phenomenological models and try to learn about low-energy realizations of the theory.

Hadron physics at low energies

Understanding how quantum chromodynamics, the theory of strong interaction, works in the low-energy region, the so-called confinement region is one of the major challenges facing physicists. Low energy hadron physics, particularly the structure of hadron is one of the most active areas of research in nuclear physics addressing this challenge. In this talk, I will review advances made in this area on a few selected topics in the last decade or so and also provide outlook for the future.

Chiral effective field theories of the strong interactions

Effective field theories of the strong interactions based on the approximate chiral symmetry of QCD provide a model-independent approach to low-energy hadron physics. We give a brief introduction to mesonic and baryonic chiral perturbation theory and discuss a number of applications. We also consider the effective field theory including vector and axial-vector mesons.

Discharge studies in Micromegas detectors in low energy hadron beams

We present measurements of discharge rates in various Micromegas detectors in low energy hadron beams for applications foreseen at the future experiments CLAS12 at JLab and MINOS at GSI. The tests were performed in the T11 beam line of the CERN/PS using hadron beams with momentum between 0.2 and 3GeV/c. The discharge probability decreases smoothly below 1GeV/c, except at some specific energies where narrow peaks are observed. The position of the peaks corresponds to the stop point of protons and heavier particles, predicted by the Geant4 simulation. Discharge rates were also measured using Micromegas prototypes equipped with a GEM foil as foreseen for the COMPASS experiment at CERN.

Research and teaching for Particle Physics at Department of Physics in Tsinghua University

We present an introduction on the history, present status and future development of the Particle Physics research and teaching at Department of Physics in Tsinghua University. The research achievements of Tsinghua particle physics group include: helicity amplitudes in non-abelian gauge field; heavy quarkonium; new physics beyond standard model; neutrino and effective field theory for low energy hadrons.

Limit on the mass of a long-lived or stable gluino

We reinterpret the generic CDF charged massive particle limit to obtain a limit on the mass of a stable or long-lived gluino. Various sources of uncertainty are examined. The $R$-hadron spectrum and scattering cross sections are modeled based on known low-energy hadron physics and the resultant uncertainties are quantified and found to be small compared to uncertainties from the scale dependence of the NLO pQCD production cross sections. The largest uncertainty in the limit comes from the unknown squark mass: when the squark -- gluino mass splitting is small, we obtain a gluino mass limit of 407 GeV, while in the limit of heavy squarks the gluino mass limit is 397 GeV. For arbitrary (degenerate) squark masses, we obtain a lower limit of 322 GeV on the gluino mass. These limits apply for any gluino lifetime longer than $\sim 30$ ns, and are the most stringent limits for such a long-lived or stable gluino.

The KLOE-2 experiment at DAΦNE upgraded in luminosity

The KLOE experiment at the DAΦNE e + e − collider of the Frascati Laboratories of INFN is going to start a second data-taking campaign (KLOE-2). The detector has been upgraded with small angle electron taggers, while the insertion near the interaction point of an inner tracker is planned for the next year. The interaction region of DAΦNE has been modified using a crabbed waist scheme. It has been successfully tested providing an improvement in luminosity of a factor 3. The KLOE-2 scientific programme [G. Amelino-Camelia et al., EPJC 68 , 619–681 (2010)] aims to further improve the experimental studies on kaon and low energy hadron physics, e.g. CKM unitarity and Lepton universality, CPT symmetry and quantum mechanics, low energy QCD, γγ physics, the contribution of hadron vacuum polarization to μ anomalous moment.

On nuclear states of % MathType!MTEF!2!1!+- % feaagaart1ev2aaatCvAUfKttLearuqr1ngBPrgarmWu51MyVXguY9 % gCGievaerbd9wDYLwzYbWexLMBbXgBcf2CPn2qVrwzqf2zLnharyav % P1wzZbItLDhis9wBH5garqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC % 0xbbL8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs0-yq % aqpepae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaaiaabe % qaamaaeaqbaaGcbaacbaGaf83saSKbaebaaaa!3D13! $$ \bar K $$ mesons

The search for nuclear states of \( \bar K \) mesons poses interesting problems for the nuclear and low energy hadron physics: the behavior of tightly bound nuclear systems with strongly correlated impurities, the new kind of binding mechanisms and the extension of effective low energy theories to the strange sector. These problems are briefly presented and a method of variational calculation of the binding energies is discussed.

Selected challenges in low-energy QCD and hadron physics

This presentation briefly addresses three basic issues of low-energy QCD: first, whether the Nambu-Goldstone scenario of spontaneous chiral symmetry breaking is well established; secondly, whether there is a dynamical entanglement of the chiral and deconfinement crossover transitions in QCD; and thirdly, what is the status of knowledge about the phase diagram of QCD at low temperature and non-zero baryon density. These three topics were injected as key words into a panel discussion at the Schladming school on Challenges in QCD. The following exposition reflects the style and character of the discussions, with no claim of completeness.

Initial State Radiation: A success story

The investigation of events with Initial State Radiation(ISR) and subsequent Radiative Return has become an impressively successful and guiding tool in low and intermediate energy hadron physics with electron positron colliders: it allows to measure hadronic cross sections and the ratio R from threshold up to the maximum energy of the colliders running at fixed energy, to clarify reaction mechanisms and reveal substructures (intermediate states and their decay mechanisms) and to search for new highly excited mesonic states with J P C = 1 − − . While being discussed since the sixties-seventies ISR became a powerful tool for experimentalists only with the development of EVA-PHOKHARA , a Monte Carlo generator developed over almost 10 years, while increasing its complexity, which is user friendly, flexible and easy to implement into the software of existing detectors.

Heavy-Heavy-Light Quark Potential in Two Approaches

There are a large number of studies about the interquark potential in hadrons. The interquark potential is mainly generated by gluon dynamics reflecting the SU(3) gauge symmetry. In particular, as many lattice QCD studies, the static and quenched approximation produces the only gluonic potential. However, realistic hadrons include not only gluons but also quarks, and quarks affect the interquark potential. We can consider two types of the quark effects, dynamical quark effects and valence quark effects. An example of the dynamical quark effects is the string breaking, which is obtained by unquenched calculation. In this study, we focus on the motional effects of finite-mass valence quarks, that is, valence quarks are not static but have a finite mass. To investigate such quark effects, we define the heavy-heavy-light (QQq) quark potential VQQq(R). It is defined as the energy of QQq systems in terms of the interheavy-quark distance R. The QQq system is constructed from two heavy quarks which are infinitely heavy and spatially fixed, and one light quark which is finite mass and moving around. Since this QQq potential effectively includes the lightquark motional effect, we can investigate the finite-mass valence quark effects to the interquark force. This QQq system is also related to the doubly charmed baryon, which has been recently discovered at the SELEX experiment.1),2) To calculate the QQq potential, we adopt the two approaches, SU(3) lattice QCD3) and a non-relativistic potential model.4) Lattice QCD is the first principle calculation based on QCD. The potential model, or the quark model, is one of the most successful analytical approaches for the low-energy hadron physics.

Hadron Production Measurements at CERN

Hadron production measurements for neutrino experiments is a well established field at CERN since the '70s. Precise prediction of atmospheric neutrino fluxes, characterization of accelerator neutrino beams, quantification of pion production and capture for neutrino factory designs, all of these would profit from hadron production measurements. In recent years, interest in such studies was revived and new generation of low-energy (from 3 to 400 GeV) hadron production experiments were built or proposed. Such experiments all share a basic design, consisting in the presence of open-geometry spectrometers, as close as possible to full angular coverage, and aiming at full particle identification. New results are now provided by Harp in the very low energy range (3 to 15 GeV/c) and by NA49 at 158 GeV/c. In the next years NA49- future will explore the medium energy range (30 to 400 GeV/c) and at LHC energies for the first time thanks to the TOTEM experiment, it will be possible to measure with unprecedented precision the total cross section beyond 1 TeV/c.