Charged Spectra Research Articles

On correlation functions in -deformed CFTs

The deformation, built from the components of the stress tensor and of a current, is a universal irrelevant deformation of two-dimensional CFTs that preserves the left-moving conformal symmetry, while breaking locality on the right-moving side. Operators in the -deformed CFT are naturally labeled by the left-moving position and right-moving momentum and transform in representations of the one-dimensional extended conformal group. We derive an all-orders formula for the spectrum of conformal dimensions and charges of the deformed CFT, which we cross-check at leading order using conformal perturbation theory. We also compute the linear corrections to the one-dimensional OPE coefficients and comment on the extent to which the correlation functions in -deformed CFTs can be obtained from field-dependent coordinate transformations.

Light flavour hadron and inclusive charged particle pT-spectra measured with the ALICE experiment at CERN

Light flavor hadron and inclusive charged particle spectra provide an interesting probe of the particle production mechanisms and the transport properties of QCD matter. Charged particle and neutral meson inclusive pT-differential cross sections in pp, p-Pb, Pb-Pb and Xe-Xe collisions have been measured by ALICE. Charged particles are studied in different multiplicity (for pp and p-Pb where available) and centrality classes (for A-A). The comparison of spectra at similar〈dNch/dη〉, the nuclear modification factors, the mean pTand particle ratios will also be presented considering those are observables important to get information on the properties of the medium formed in the collisions. Comparisons with model calculations will also be discussed.

Distributions of the Transverse Momentum and Pseudorapidity of Charged Particles in pp Collisions at 0.9 TeV

We have studied the charged particles spectra for the pseudorapidity region of ∣η∣ < 2.5, the multiplicity of charged particles, its dependence on pT as well as on η and the relation between average pT and charged particles multiplicity in pp collisions at √s = 0.9 TeV. For simulations, we have used the EPOS-LHC, EPOS-1.99, QGSJETII-04, and SIBYLL-2.3c models and compared their predictions with the experimental data of ATLAS experiment. For the pT distribution, predictions of the Sibyll-2.3c are matching with the experimental data in a region of 0.5 GeV/c < pT < 0.8 GeV/c and EPOS-1.99 model results are near to the experimental data for 0.5 GeV/c < pT < 1.5 GeV/c. For the case of average pT, EPOS-LHC, and Sibyll-2.3c predictions are closer to the experimental data. For the pseudorapidity charged particle density distributions, QGSJETII-04 model predictions are better describing the experimental data.

Terahertz conductivity and coupling between geometrical and plasmonic resonances in nanostructures

Terahertz conductivity spectra of charges moving ballistically in one-, two-, and three-dimensional infinitely deep rectangular potential wells were investigated theoretically using semiclassical and quantum Kubo formulas. The conductivity spectrum of a degenerate electron gas in these nanostructures exhibits a series of geometrical resonances. These further couple with plasmon resonances occurring in isolated structures: qualitatively different interaction regimes are found in one-, two-, and three-dimensional nanostructures. In contrast, the response of a nondegenerate electron gas smears into a single broad band due to the excessive spectral broadening caused by the wide distribution of charge velocities.

On the quantization of charged black holes with allowance for the cosmological constant

The paper considers a spherically symmetric configuration of the gravitational and electromagnetic fields with allowance to the cosmological constant, and its quantization. After dimensional reduction, the original action is transformed to new variables in the R- and T-regions. The exclusion of the non-dynamic degree of freedom from the obtained action leads to an action for the geodesic in the configuration space, which proves to be conformally flat. We use the Gitman–Tyutin formalism for the obtained dynamical system, which Lagrange function is degenerate. After performing a suitable canonical transformation, the constraints found from the Lagrange function are reduced to the canonical form. Herewith the physical part of the Hamilton function vanishes. To construct quantum theory, we introduce additional physical quantities – charge and mass functions. Since Hamilton operator equals zero, it leads to the fact that the desired wave function of the system obeys only the eigenvalue equations for the mass and charge operators. The solution of these equations leads to continuous charge and mass spectra.

MsCRUSH: Fast Tandem Mass Spectral Clustering Using Locality Sensitive Hashing.

Large-scale proteomics projects often generate massive and highly redundant tandem mass spectra. Spectral clustering algorithms can reduce the redundancy in these data sets and thus speed up database searching for peptide identification, a major bottleneck for proteomic data analysis. The key challenge of spectral clustering is to reduce the redundancy in the MS/MS spectra data while retaining sufficient sensitivity to identify peptides from the clustered spectra. We present the software msCRUSH, which implements a novel spectral clustering algorithm based on the locality sensitive hashing technique. When tested on a large-scale proteomic data set consisting of 23.6 million spectra (including 14.4 million spectra of charge 2+), msCRUSH runs 6.9-11.3 times faster than the state-of-the-art spectral clustering software, PRIDE Cluster, while achieving higher clustering sensitivity and comparable accuracy. Using the consensus spectra reported by msCRUSH, commonly used spectra search engines MSGF+ and Mascot can identify 3 and 1% more unique peptides, respectively, compared with the identification results from the raw MS/MS spectra at the same false discovery rate (1% FDR) of peptide level. msCRUSH is implemented in C++ and is released as open-source software.

Discrimination of incoherent vortex states of light.

Coherence vortex (CV) states provide a new way for optical manipulation and communication. As a promising option for increasing the data-transmission capacity, CV multiplexing warrants investigation. However, few studies have focused on discriminating and sorting CV states with different topological charges. In this work, we examine the cross-spectral density (CSD) of a CV state embedded in an incoherent light field and so-called incoherent vortex (ICV). Given a multiplexed ICV, we propose a method to recognize the constituting single ICVs therein. Our analytical results, which are derived according to the coherence theory and the paraxial propagation law and are given in analytical forms, show that the CSD can reveal the topological charge spectrum of a multiplexed incoherent Laguerre-Gaussian mode. This proposal can be used for free-space communication and remote sensing where light fields with low coherence are preferable to completely coherent beams.

Valence band behaviour of zirconium oxide, Photoelectron and Auger spectroscopy study

In this study X-ray Photoelectron Spectroscopy and Ultraviolet Photoelectron Spectroscopy were combined to investigate the effect of oxygen incorporation on the valence band behaviour of ZrOx. The Auger transitions involving valence bands are found to mimic the self-folded density of state measured using Ultraviolet Photoelectron Spectroscopy. The valence band once constructed in a sub-oxide form, stays at a fixed energy position despite the change in the stoichiometry. This behaviour is found to be useful in setting a reference for X-ray Photoelectron Spectroscopy charge correction. The results of the charged corrected spectra were compared to other methods and found to be in great agreement. Finally, a correlation between the core-level binding energy and the structural property of ZrOx is given.

Charge measurement of cosmic ray nuclei with the plastic scintillator detector of DAMPE

One of the main purposes of the DArk Matter Particle Explorer (DAMPE) is to measure the cosmic ray nuclei up to several tens of TeV or beyond, whose origin and propagation remains a hot topic in astrophysics. The Plastic Scintillator Detector (PSD) on top of DAMPE is designed to measure the charges of cosmic ray nuclei from H to Fe and serves as a veto detector for discriminating gamma-rays from charged particles. We propose in this paper a charge reconstruction procedure to optimize the PSD performance in charge measurement. Essentials of our approach, including track finding, alignment of PSD, light attenuation correction, quenching and equalization correction are described detailedly in this paper after a brief description of the structure and operational principle of the PSD. Our results show that the PSD works very well and almost all the elements in cosmic rays from H to Fe are clearly identified in the charge spectrum.

Tensionless strings and the weak gravity conjecture

We test various conjectures about quantum gravity for six-dimensional string compactifications in the framework of F-theory. Starting with a gauge theory coupled to gravity, we analyze the limit in Kähler moduli space where the gauge coupling tends to zero while gravity is kept dynamical. We show that such a limit must be located at infinite distance in the moduli space. As expected, the low-energy effective theory breaks down in this limit due to a tower of charged particles becoming massless. These are the excitations of an asymptotically tensionless string, which is shown to coincide with a critical heterotic string compactified to six dimensions.For a more quantitative analysis, we focus on a U(1) gauge symmetry and use a chain of dualities and mirror symmetry to determine the elliptic genus of the nearly tensionless string, which is given in terms of certain meromorphic weak Jacobi forms. Their modular properties in turn allow us to determine the charge-to-mass ratios of certain string excitations near the tensionless limit. We then provide evidence that the tower of asymptotically massless charged states satisfies the (sub-)Lattice Weak Gravity Conjecture, the Completeness Conjecture, and the Swampland Distance Conjecture. Quite remarkably, we find that the number theoretic properties of the elliptic genus conspire with the balance of gravitational and scalar forces of extremal black holes, such as to produce a narrowly tuned charge spectrum of superextremal states. As a byproduct, we show how to compute elliptic genera of both critical and non-critical strings, when refined by Mordell-Weil U(1) symmetries in F-theory.

Measurement of charged particle spectra in minimum-bias events from proton\u2013proton collisions at sqrt{s}=13,text {TeV}

Pseudorapidity, transverse momentum, and multiplicity distributions are measured in the pseudorapidity range |eta | < 2.4 for charged particles with transverse momenta satisfying p_{mathrm {T}} > 0.5,text {GeV} in proton–proton collisions at a center-of-mass energy of sqrt{s} = 13,text {TeV} . Measurements are presented in three different event categories. The most inclusive of the categories corresponds to an inelastic mathrm {p}mathrm {p} data set, while the other two categories are exclusive subsets of the inelastic sample that are either enhanced or depleted in single diffractive dissociation events. The measurements are compared to predictions from Monte Carlo event generators used to describe high-energy hadronic interactions in collider and cosmic-ray physics.

Study on the reaction of trimethylaluminum dimer and ammonia based on density functional theory

AlN is prepared through the reaction of trimethylaluminum and ammonia by MOCVD. This study investigated the stable configurations of trimethylaluminum, and provided their primary bond lengths and bond angles. The reaction between the most stable configuration of TMA(C2v) dimer and NH3, was investigated, with the detailed reaction process provided. Further, a complex TMA:NH3 and a monomer of TMA were produced. The electronic structure and some optical properties of TMA:NH3, such as the density of states, Mulliken charge, bond population, band gap, absorption and reflectivity spectra, were further investigated. The results offer theoretical data for the application of the material TMA:NH3.

Abstract 2693: Mass spectrometric approach to identify N-glycosylation of light chain in patients with immunoglobulin light chain amyloidosis (AL)

Abstract AL is a rare plasma cell disorder, resulting from clonal bone marrow plasma cells secreting immunoglobulin light chains (LC), which aggregate abnormally into fibrils, and leads to amyloid deposits in different organs. Previous studies using LC immunopurification and MALDI-TOF/MS (MASS-FIX) on patients with known plasma cell disorders (PCDs), demonstrated that monoclonal LC from AL patients display unusually complex mass to charge spectra (m/z) for their LCs at much higher frequencies than other PCDs such as multiple myeloma. We hypothesized that these were post-translational modification, presumably glycoforms. Here, we report investigations into LC glycosylation using MASS- FIX. Serum from 212 lambda and 72 kappa AL patients were collected following Mayo Clinic IRB guidelines. LC was purified from serum using nanobody enrichment method, followed by MASS-FIX. The LCs spectra acquired on MASS-FIX were visually analyzed and were classified into different patterns. The kappa and lambda LC mass distributions with abnormal complex patterns were interrogated for the presence of glycosylation by exposure to the LC to a deglycoslylating enzyme (PNGase F) and analysis of LC mass distribution using MASS-FIX and by LC-ESI-Orbitrap. Monoclonal LCs demonstrating significantly mass shifted peak outside the normal kappa and lambda mass distribution were observed in 31% of kappa and 6% of lambda patients with AL. In order to determine if this characteristic mass shift was due to glycosylation, 16 kappa and 6 lambda LCs were treated with a PNGase F and LC spectrum were re-examined by MASS-FIX and LC-ESI-Orbitrap. The monoclonal LCs whose masses were significantly shifted beyond normal kappa and lambda mass distributions were found to shift to lower molecular weight after PNGase F treatment, confirming the presence of N-glycosylation. Moreover, an additional 5 kappa and 23 lambda samples had other complex patterns, typically with multiple additional peaks at increments of 162 Da. These samples did not shift with PNGase F suggesting either glycation or O-glycosylation. This work is significant as it confirms that N-glycosylated LCs are over represented in patients with AL in comparison to other PCDs. In patients with AL, the frequency of N-glycosylation of kappa LC clones was 5 times higher than that of lambda LC clones. More work is needed to explore the mechanism for this finding, the role of glycosylation in fibril formation, and the other complex patterns observed. In addition, MASS-FIX method used in this work is currently being validated in the clinical lab such that rapid detection of N-glycosylation in patients with monoclonal gammopathies will be possible routinely, potentially leading to earlier clinical suspicion for AL among patients with monoclonal gammopathies and hence to earlier detection of AL. Citation Format: Sanjay Kumar, Angela Dispenzieri, Surendra Dasari, Paolo Milani, Giampaolo Merlini, MeLea Hetrick, David Barnidge, Benjamin Madden, David Murray. Mass spectrometric approach to identify N-glycosylation of light chain in patients with immunoglobulin light chain amyloidosis (AL) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2693.

An infinite swampland of U(1) charge spectra in 6D supergravity theories

We analyze the anomaly constraints on 6D supergravity theories with a single abelian U(1) gauge factor. For theories with charges restricted to q = ±1, ±2 and no tensor multiplets, anomaly-free models match those models that can be realized from F-theory compactifications almost perfectly. For theories with tensor multiplets or with larger charges, the F-theory constraints are less well understood. We show, however, that there is an infinite class of distinct massless charge spectra in the “swampland” of theories that satisfy all known quantum consistency conditions but do not admit a realization through F-theory or any other known approach to string compactification. We also compare the spectra of charged matter in abelian theories with those that can be realized from breaking nonabelian SU(2) and higher rank gauge symmetries.

Timing Recollision in Nonsequential Double Ionization by Intense Elliptically Polarized Laser Pulses

We examine correlated electron and doubly charged ion momentum spectra from strong field double ionization of neon employing intense elliptically polarized laser pulses. An ellipticity-dependent asymmetry of correlated electron and ion momentum distributions has been observed. Using a 3D semiclassical model, we demonstrate that our observations reflect the subcycle dynamics of the recollision process. Our Letter reveals a general physical picture for recollision impact double ionization with elliptical polarization and demonstrates the possibility of ultrafast control of the recollision dynamics.

Doping evolution of charge and spin excitations in two-leg Hubbard ladders: Comparing DMRG and FLEX results

We study the magnetic and charge dynamical response of a Hubbard model in a two-leg ladder geometry using the density matrix renormalization group (DMRG) method and the random phase approximation within the fluctuation-exchange approximation (RPA+FLEX). Our calculations reveal that RPA+FLEX can capture the main features of the magnetic response from weak up to intermediate Hubbard repulsion for doped ladders, when compared with the numerically exact DMRG results. However, while at weak Hubbard repulsion both the spin and charge spectra can be understood in terms of weakly-interacting electron-hole excitations across the Fermi surface, at intermediate coupling DMRG shows gapped spin excitations at large momentum transfer that remain gapless within the RPA+FLEX approximation. For the charge response, RPA+FLEX can only reproduce the main features of the DMRG spectra at weak coupling and high doping levels, while it shows an incoherent character away from this limit. Overall, our analysis shows that RPA+FLEX works surprisingly well for spin excitations at weak and intermediate Hubbard $U$ values even in the difficult low-dimensional geometry such as a two-leg ladder. Finally, we discuss the implications of our results for neutron scattering and resonant inelastic x-ray scattering experiments on two-leg ladder cuprate compounds.

Study of the optimal configuration for a Gas Electron Multiplier aimed at plasma impurity radiation monitoring

For the purpose of monitoring the level of plasma impurity (especially tungsten) and its distribution reconstruction at tokamaks (ITER in particular), a Soft X-Ray (SXR) tomographic diagnostics based on Gas Electron Multiplier (GEM) detectors with energy discrimination has been extensively considered for a while. Coupled with advanced electronics, GEM detectors offer excellent time and space resolution, as well as a charge spectrum from which the SXR photon spectrum can be deconvolved. In addition, they are less subjected to a neutron damage as compared to standard semiconductor diodes. This contribution highlights the latest studies supporting the development of such diagnostics focusing on laboratory tests to examine: (a) the impact of GEM holes geometry on the properties and distribution of the electron avalanche; (b) the effect of the high rate photon flux on GEM foil performance; and (c) the optimal electric field distribution.

DAMPE squib? Significance of the 1.4 TeV DAMPE excess

We present a Bayesian and frequentist analysis of the DAMPE charged cosmic ray spectrum. The spectrum, by eye, contained a spectral break at about 1TeV and a monochromatic excess at about 1.4TeV. The break was supported by a Bayes factor of about 1010 and we argue that the statistical significance was resounding. We investigated whether we should attribute the excess to dark matter annihilation into electrons in a nearby subhalo. We found a local significance of about 3.6σ and a global significance of about 2.3σ, including a two-dimensional look-elsewhere effect by simulating 1000 pseudo-experiments. The Bayes factor was sensitive to our choices of priors, but favoured the excess by about 2 for our choices. Thus, whilst intriguing, the evidence for a signal is not currently compelling.

Strange particle production and hypernucleus formation in medium and high energy heavy-ion collisions

The nuclear matter at supra-saturation densities might be created in medium and high energy heavy-ion collisions. The strangeness ingredient in dense nuclear matter impacts the equation of state and maybe exists in the neutron stars. On the other hand, heavy-ion collisions provide a unique way for producing the neutron-rich hypernuclides. In this article, the new progress on strangeness physics in heavy-ion collisions is reviewed. Possible experiments at the high-intensity heavy-ion accelerator facility (HIAF) are to be discussed, in particular on the topics of the high-density nuclear equation of state and hypernuclide in the neutron-rich domain. Within the framework of the Lanzhou quantum molecular dynamics (LQMD) model, the strangeness production and high-density nuclear equation of state in heavy-ion collisions near threshold energies has been investigated, i.e., for the reactions of $^{58}$Ni+$^{58}$Ni and $^{197}$Au+$^{197}$Au. The formation mechanism of $\Lambda$-hyperfragments in heavy-ion collisions is to be investigated. A coalescence approach is developed for constructing the primary fragments in phase space. The secondary decay process of the fragments is described by the well-known statistical code. The impacts of nuclear equation of state on the hyperfragment formation are discussed. The mass, charge and kinetic energy spectra of hypernuclides produced in heavy-ion collisions are thoroughly analyzed. It is found that the kaon yields in the high kinetic energy domain are useful for extracting the high-density nuclear equation of state. The $K^{+}$ yields are strongly suppressed with a hard equation of state. However, the hyperon production is weakly influenced by the incompressibility of nuclear matter. The $\Lambda$-nucleon potential impacts the hypernuclide formation, i.e., the attractive potential enhancing the hypernuclide yields. The heavy-ion collisions are available to produce the light mass neutron-rich hypernuclides and the mid-central collisions are favorable for the medium mass hypernuclide formation. Free hyperons are captured by nucleonic fragments to form hypernuclides in the domain of lower kinetic energies and narrower rapidities. A soft equation of state is available for producing the hyperfragments. The results are very valuable for the forthcoming hypernuclide physics at HIAF.

Secondary radiation measurements for particle therapy applications: charged particles produced by 4He and 12C ion beams in a PMMA target at large angle

Proton and carbon ion beams are used in the clinical practice for external radiotherapy treatments achieving, for selected indications, promising and superior clinical results with respect to x-ray based radiotherapy. Other ions, like have recently been considered as projectiles in particle therapy centres and might represent a good compromise between the linear energy transfer and the radiobiological effectiveness of ion and proton beams, allowing improved tumour control probability and minimising normal tissue complication probability. All the currently used p, and ion beams allow achieving sharp dose gradients on the boundary of the target volume, however the accurate dose delivery is sensitive to the patient positioning and to anatomical variations with respect to photon therapy. This requires beam range and/or dose release measurement during patient irradiation and therefore the development of dedicated monitoring techniques. All the proposed methods make use of the secondary radiation created by the beam interaction with the patient and, in particular, in the case of ion beams are also able to exploit the significant charged radiation component.Measurements performed to characterise the charged secondary radiation created by and particle therapy beams are reported. Charged secondary yields, energy spectra and emission profiles produced in a poly-methyl methacrylate (PMMA) target by and beams of different therapeutic energies were measured at 60° and 90° with respect to the primary beam direction. The secondary yield of protons produced along the primary beam path in a PMMA target was obtained. The energy spectra of charged secondaries were obtained from time-of-flight information, whereas the emission profiles were reconstructed exploiting tracking detector information. The obtained measurements are in agreement with results reported in the literature and suggests the feasibility of range monitoring based on charged secondary particle detection: the implications for particle therapy monitoring applications are also discussed.