Proton Pairs Research Articles

Search for charged Higgs bosons produced in vector boson fusion processes and decaying into vector boson pairs in proton\u2013proton collisions at sqrt{s} = 13,{text {TeV}}

A search for charged Higgs bosons produced in vector boson fusion processes and decaying into vector bosons, using proton–proton collisions at sqrt{s}=13,{text {TeV}} at the LHC, is reported. The data sample corresponds to an integrated luminosity of 137,{text {fb}}^{-1} collected with the CMS detector. Events are selected by requiring two or three electrons or muons, moderate missing transverse momentum, and two jets with a large rapidity separation and a large dijet mass. No excess of events with respect to the standard model background predictions is observed. Model independent upper limits at 95% confidence level are reported on the product of the cross section and branching fraction for vector boson fusion production of charged Higgs bosons as a function of mass, from 200 to 3000,{text {GeV}}. The results are interpreted in the context of the Georgi–Machacek model.

Atomically Dispersed Manganese Lewis Acid Sites Catalyze Electrohydrogenation of Nitrogen to Ammonia

Atomically Dispersed Manganese Lewis Acid Sites Catalyze Electrohydrogenation of Nitrogen to Ammonia

Pemanfaatan Methylene Blue dan Kulit Pisang Sebagai Komponen RFB (Redox Flow Battery)

RFB (Redox Flow Battery) is a secondary battery that provides energy conversion between chemistry and electricity through an alternating redox reaction by 2 pairs of electrons and protons. RFB with active ingredient Vanadium (VRB) is a type of RFB that is widely used and has problems such as the price of Vanadium is expensive, is toxic and the solvent (H2SO4) is corrosive. Therefore, an inexpensive and environmentally friendly organic electrolyte component emerged, namely Methylene Blue and banana peels. Methylene Blue has 2 electron-proton pairs which provide a reversible redox reaction and have the potential as an active ingredient in the RFB electrolyte. Banana peels have potential as an electrolyte solvent because they contain carbohydrates, citric acid and mineral electrolytes (potassium, sodium salt, phosphorus and magnesium) which support the electrolyte properties of banana peels. The stages of making electrolytes by fermentation of banana peel solution, addition of Methylene Blue and testing (galvanostatic and stress). The test results showed that Methylene Blue was able to provide the best performance (efficiency) on RFB and banana peels as an electrolyte in the battery was able to produce a voltage exceeding the VRB output voltage.

ESCASA: Analytical estimation of atomic coordinates from coarse-grained geometry for nuclear-magnetic-resonance-assisted protein structure modeling. I. Backbone and Hβ protons.

A method for the estimation of coordinates of atoms in proteins from coarse-grained geometry by simple analytical formulas (ESCASA), for use in nuclear-magnetic-resonance (NMR) data-assisted coarse-grained simulations of proteins is proposed. In this paper, the formulas for the backbone Hα and amide (HN ) protons, and the side-chain Hβ protons, given the Cα -trace, have been derived and parameterized, by using the interproton distances calculated from a set of 140 high-resolution non-homologous protein structures. The mean standard deviation over all types of proton pairs in the set was 0.44 Å after fitting. Validation against a set of 41 proteins with NMR-determined structures, which were not considered in parameterization, resulted in average standard deviation from average proton-proton distances of the NMR-determined structures of 0.25 Å, compared to 0.21 Å obtained with the PULCHRA all-atom-chain reconstruction algorithm and to the 0.12 Å standard deviation of the average-structure proton-proton distance of NMR-determined ensembles. The formulas provide analytical forces and can, therefore, be used in coarse-grained molecular dynamics.

Proton correlations and apparent intermittency in the UrQMD model with hadronic potentials

It is shown that the inclusion of hadronic interactions, and in particular nuclear potentials, in simulations of heavy ion collisions at the SPS energy range can lead to obvious correlations of protons. These correlations contribute significantly to an intermittency analysis as performed at the NA61 experiment. The beam energy and system size dependence is studied by comparing the resulting intermittency index for heavy ion collisions of different nuclei at beam energies of 40A, 80A and 150A GeV. The resulting intermittency index from our simulations is similar to the reported values of the NA61 collaboration, if nuclear interactions are included. The observed apparent intermittency signal is the result of the correlated proton pairs with small relative transverse momentum Δpt, which would be enhanced by hadronic potentials, and this correlation between the protons is slightly influenced by the coalescence parameters and the relative invariant four-momentum qinv cut.

First observation of collective rotational bands in neutron-rich 142La and the study of octupole/triaxial deformations in 142,143La

Collective rotational bands were observed for the first time in neutron-rich odd–odd [Formula: see text]La by means of [Formula: see text]-[Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text]-[Formula: see text]-[Formula: see text] coincidence measurements of prompt fission [Formula: see text] rays from [Formula: see text]Cf using multi-detector array Gammasphere. Similarity between the yrast band of [Formula: see text]La and those of neighboring [Formula: see text]La, [Formula: see text]Ce was found and interpreted as quasiparticle excitations. PES calculations suggested triaxial deformation for the ground state of 142La. Considerable triaxial and near zero octupole deformations were deduced for the yrast band of [Formula: see text]La by the TRS model calculations. The band-crossing observed in the yrast band of [Formula: see text]La was interpreted to be caused by alignment of the (h[Formula: see text])2 proton pair, and the crossing frequency was best reproduced by the TRS calculations taking into account triaxial deformations. In contrast to the interpretations for the band crossing of [Formula: see text]La, alignments of the (i[Formula: see text])2 neutron pair were found to be responsible for the band-crossing of the yrast band in the neighboring even-N [Formula: see text]La, and triaxial degree of freedom was found to play a more significant role than octupole deformations in the nucleus, although its [Formula: see text] values deduced are large.

Global study of separable pairing interaction in covariant density functional theory

A systematic global investigation of pairing properties based on all available experimental data on pairing indicators has been performed for the first time in the framework of covariant density functional theory. It is based on separable pairing interaction of Ref. [1]. The optimization of the scaling factors of this interaction to experimental data clearly reveals its isospin dependence in neutron subsystem. However, the situation is less certain in proton subsystem since similar accuracy of the description of pairing indicators can be achieved both with isospin-dependent and mass-dependent scaling factors. The differences in the functional dependencies of scaling factors lead to the uncertainties in the prediction of proton and neutron pairing properties which are especially pronounced at high isospin and could have a significant impact on some physical observables. For a given part of nuclear chart the scaling factors for spherical nuclei are smaller than those for deformed ones; this feature exists also in non-relativistic density functional theories. Its origin is traced back to particle-vibration coupling in odd-$A$ nuclei which is missing in all existing global studies of pairing. Although the present investigation is based on the NL5(E) covariant energy density functional (CEDF), its general conclusions are expected to be valid also for other CEDFs built at the Hartree level.

Measurements of {mathrm{p}} {mathrm{p}} rightarrow {mathrm{Z}} {mathrm{Z}} production cross sections and constraints on anomalous triple gauge couplings at sqrt{s} = 13,text {TeV}

The production of Z boson pairs in proton–proton ({mathrm{p}} {mathrm{p}} ) collisions, {{mathrm{p}} {mathrm{p}} rightarrow ({mathrm{Z}}/gamma ^*)({mathrm{Z}}/gamma ^*) rightarrow 2ell 2ell '}, where {ell ,ell ' = {mathrm{e}}} or {{upmu }}, is studied at a center-of-mass energy of 13,text {TeV} with the CMS detector at the CERN LHC. The data sample corresponds to an integrated luminosity of 137,text {fb}^{-1}, collected during 2016–2018. The {mathrm{Z}} {mathrm{Z}} production cross section, sigma _{text {tot}} ({mathrm{p}} {mathrm{p}} rightarrow {mathrm{Z}} {mathrm{Z}} ) = 17.4 pm 0.3 ,text {(stat)} pm 0.5 ,text {(syst)} pm 0.4 ,text {(theo)} pm 0.3 ,text {(lumi)} text { pb} , measured for events with two pairs of opposite-sign, same-flavor leptons produced in the mass region {60< m_{ell ^+ell ^-} < 120,text {GeV}} is consistent with standard model predictions. Differential cross sections are also measured and agree with theoretical predictions. The invariant mass distribution of the four-lepton system is used to set limits on anomalous {mathrm{Z}} {mathrm{Z}} {mathrm{Z}} and {{mathrm{Z}} {mathrm{Z}} gamma } couplings.

Proton pairing in neutron stars from chiral effective field theory

We study the $^{1}S_{0}$ proton pairing gap in $\ensuremath{\beta}$-equilibrated neutron star matter within the framework of chiral effective field theory. We focus on the role of three-body forces, which strongly modify the effective proton-proton spin-singlet interaction in dense matter. We find that three-body forces generically reduce both the size of the pairing gap and the maximum density at which proton pairing may occur. The pairing gap is computed within Bardeen-Cooper-Schrieffer theory using a single-particle dispersion relation calculated up to second order in perturbation theory. Model uncertainties are estimated by varying the nuclear potential (its order in the chiral expansion and high-momentum cutoff) and the choice of single-particle spectrum in the gap equation. We find that a second-order perturbative treatment of the single-particle spectrum suppresses the proton $^{1}S_{0}$ pairing gap relative to the use of a free spectrum. We estimate the critical temperature for the onset of proton superconductivity to be ${T}_{c}=(3.2\text{--}5.1)\ifmmode\times\else\texttimes\fi{}{10}^{9}$ K, which is consistent with previous theoretical results in the literature and marginally within the range deduced from a recent Bayesian analysis of neutron star cooling observations.

Isobaric-multiplet mass equation in a macroscopic-microscopic approach

We study the a, b and c coefficients of the isobaric-multiplet mass equation using a macroscopic-microscopic approach developed by P. Moeller and his collaborators in ADNDT 59, 185 (1995) and ADNDT 109-110, 1 (2016). We show that already the macroscopic part of the finite-range liquid-drop model (FRLDM) describes the general trend of the a and b coefficients relatively well, while the staggering behavior of b coefficients for doublets and quartets can be understood in terms of the difference of average proton and neutron pairing energies. The sets of isobaric masses, predicted by the full macroscopic-microscopic approaches, are used to explore the general trends of IMME coefficients up to A=100. We conclude that while the agreement for a coefficients is quite satisfactory, the global approaches have less sensitivity to predict the staggering pattern observed for b coefficients of doublets and quartets. The best set of theoretical b coefficients for multiplets up to about A=100 is used to predict masses of proton-rich nuclei based on the known experimental masses of neutron-rich mirror partners, and subsequently to investigate their one- and two-proton separation energies. The estimated position of the proton-drip line is in fair agreement with known experimental data. These masses are important for simulations of the astrophysical rp-process.

Computational 1 H and 13 C NMR of the trimeric monoterpenoid indole alkaloid strychnohexamine: Selected spectral updates.

Very large trimeric indole alkaloid strychnohexamine, with empirical formula C59 H60 N6 O (66 second-row atoms and 60 protons), has been subjected to the state-of-the-art computation of the 1 H and 13 C nuclear magnetic resonance (NMR) chemical shifts of its configurational isomers at each of the 14 asymmetric centers. Several spectral reassignments and corrections of 1 H and 13 C NMR spectra of this alkaloid were suggested based on the PBE0/pcSseg-2//pcseg-2 calculation of its NMR chemical shifts. Thus, all pairs of diastereotopic protons were assigned together with four aromatic carbon resonances of C-9 and C-11, C-9″, and C-11″. In addition, the unassigned chemical shifts of carbon C-23″ and proton at C-3' in, accordingly, 13 C and 1 H NMR spectra were predicted.

Thermal evolution of neutron stars described within the equation of state with induced surface tension

AbstractWe present a modeling of the thermal evolution of the neutron stars, incorporating an effect of neutron and proton pairing. The considered equation of state with induced surface tension (IST) reproduces properties of normal nuclear matter, fulfills the proton flow constraint, provides a high‐quality description of particle yields created in heavy‐ion collisions, and is equally compatible with the constraints from astrophysical observations and the GW170817 event. The model features strong direct Urca processes for the stars above 1.91 M⊙. Our results show a very good agreement with the available cooling data, including observational data of the compact object in the center of the Cassiopeia A (Cas A), even without introducing nuclear pairing. The rapid cooling rate of the Cas A can be also reproduced by a 1.66 M⊙ star with an atmosphere of light elements, high‐mass 1.955 − 1.96 M⊙ stars with paired and unpaired matter, as well as by a 1.91 M⊙ star with inclusion of neutron and proton pairings in the singlet channel.

Backbending Phenomena in Even–Even $${}^{\boldsymbol{162{-}172}}$$Hf Isotopes

This study probes the backbending phenomena in even–even $${}^{162{-}172}$$ Hf isotopes. Experimental ground-state rotational energies up to $$J^{\pi}=36^{+}$$ states were used to calculate the variation of the moment of inertia against the square of rotational angular frequency. The result shows that the calculated values of the moment of inertia for heavy mass isotopes; $${}^{170}$$ Hf and $${}^{172}$$ Hf, increase progressively over an increasing square of angular frequency. However, the $${}^{162}$$ Hf, $${}^{164}$$ Hf, $${}^{166}$$ Hf, and $${}^{168}$$ Hf isotopes exhibit a sharp bending with an $$S$$ -shaped curve. While $$J^{(1)}$$ the kinematical moment of inertia maintains the backbending shapes in these nuclei, the dynamical moment of inertia $$J^{(2)}$$ shows significant responses to the changes in $$J^{(1)}$$ and $$\omega_{\mathrm{rot}}$$ , giving each of these isotopes a unique signature. These backbending shapes, $$J^{(1)}$$ increasing, and the fluctuations in $$J^{(2)}$$ may be due to a rapid quasiparticle alignment in the considered Hf nuclei. The closeness of the crossing frequency between the first and second bands is also investigated, we propose that the second band crossing is due to the alignment of a pair of protons (proton-pair alignment).

Cooperative origin of proton pair diffusivity in yttrium substituted barium zirconate

Proton conduction is an important property for fuel cell electrolytes. The search for molecular details on proton transport is an ongoing quest. Here, we show that in hydrated yttrium doped barium zirconate using X-ray and neutron diffraction that protons tend to localize near the dopant yttrium as a conjugated superstructure. The proton jump time measured using quasi-elastic neutron scattering follows the Holstein-Samgin polaron model, revealing that proton hopping is weakly coupled to the high-frequency O-H stretching motion, but strongly coupled to low-frequency lattice phonons. The ratio of the proton polaron effective mass, m*, and the proton mass is m*/m = 2, when coupled to the Zr-O stretching mode, giving experimental evidence of proton pairing in perovskites, as a result of proton-phonon coupling. Possible pathways of a proton pair are provided through Nudge Elastic Band calculations. The pairing of protons, when jumping, is discussed in context of a cooperative protonic charge transport process.

Inclusion complexes of tricyclic drugs and β-cyclodextrin: Inherent chirality and dynamic behaviour.

Amitriptyline (AMT) and cyclobenzaprine (CBZ) are tricyclic drugs used as antidepressant and muscle relaxant, respectively. They show inherently chirality, i.e. they are chiral due to the lack of any symmetry element. As they are used as racemic mixture, diastereomeric inclusion complexes are formed via encapsulation in homochiral βCD. In this work we show that a suitable combination of NMR methods easily provides details on the chiral recognition, geometry of complexation, rotational dynamics and spatial proximity of selected atom pairs. In particular, we show that 13C NMR can be used to unambiguously assess chiral recognition, demonstrating a higher performance over 1H NMR. The mole fraction of the bound drug and the association constant can be worked out through diffusion experiments, whereas the combination of non-selective, selective and bi-selective relaxation spectra gave insights into the rotational motion of the complexed drug and the spatial proximity of selected proton pairs. The toolkit here proposed provides a thorough characterization of CD/drug inclusion complexes from a physicochemical point of view. This can constructively complement the conventional pharmacological and pharmacokinetic experiments, and can shed light on the understanding of CD/drug formulations.

Nuclear Pairing Gaps and Neutron Star Cooling

We study the cooling of isolated neutron stars with particular regard to the importance of nuclear pairing gaps. A microscopic nuclear equation of state derived in the Brueckner-Hartree-Fock approach is used together with compatible neutron and proton pairing gaps. We then study the effect of modifying the gaps on the final deduced neutron star mass distributions. We find that a consistent description of all current cooling data can be achieved and a reasonable neutron star mass distribution can be predicted employing the (slightly reduced by about 40%) proton 1S0 Bardeen-Cooper-Schrieffer (BCS) gaps and no neutron 3P2 pairing.

Sequences of single-particle energy levels of even–even SHN with Z = 116−132 based on α-decay systematics

The [Formula: see text]-decay half-lives, [Formula: see text], for five heavy and nine superheavy even–even nuclei with [Formula: see text] and [Formula: see text], respectively, have been calculated within the density-dependent cluster model. The [Formula: see text]-nucleus potential was derived by employing the double-folding model with a realistic [Formula: see text] interaction whose exchange part has a finite-range. We considered several isotopes for each [Formula: see text]-value. The behavior of [Formula: see text] against the neutron number variation for different isotopes of each element is investigated. We found a clear similarity in the behavior of [Formula: see text] for the isotopes of a number of successive elements. The proton pair in the emitted [Formula: see text] particle, for these elements, comes from the same proton energy level. Also, the behavior of [Formula: see text] with the parent neutron number, for different isotopes of an element, was found to be governed by the existence of neutron magic number or neutron-level closure. The possibility to correlate the behavior of [Formula: see text] for several isotopes of a specific element with the proton and neutron energy levels of this element is investigated. Moreover, the behavior of [Formula: see text] when adding successive proton pairs to fill the energy level at different neutron numbers is studied. This work can be considered as a significant step forward to correlate the behavior of [Formula: see text] with the energy levels.

Realistic analytical approach for α decay and clustering

We approximate the realistic $\ensuremath{\alpha}$-core nuclear interaction between the inner turning point and Coulomb barrier, derived within the double folding procedure, by a parabolic dependence. It turns out that the corresponding harmonic oscillator frequency is concentrated in a narrow interval around $\ensuremath{\hbar}{\ensuremath{\omega}}_{1}\ensuremath{\approx}$ 9 MeV for all analyzed transitions from even-even and odd-mass $\ensuremath{\alpha}$ emitters. The penetrability through the nuclear barrier has an exponential dependence on the ratio between the fragmentation potential and this harmonic oscillator frequency. On the other hand, the Coulomb penetrability has the standard dependence on the Coulomb parameter. Our analysis revealed that the reduced width, extracted by using the nuclear plus Coulomb penetrability factors, exponentially decreases versus the number of $\ensuremath{\alpha}$ clusters along all analyzed $\ensuremath{\alpha}$ lines, except one region where it increases by approaching the neutron magic number ${N}_{\mathrm{mag}}=126$. In that case, the number of valence proton pairs is much smaller than the number of valence neutron pairs. The reduced width exponentially depends on the magic neutron-proton asymmetry above doubly magic nuclei. These dependencies allow us to propose a systematics for reduced widths in terms of the quartet number and magic asymmetry evaluated above the closest doubly magic nuclei.

Measurement of the transverse momentum distribution of Drell\u2013Yan lepton pairs in proton\u2013proton collisions at sqrt{s}=13,TeV with the ATLAS detector

This paper describes precision measurements of the transverse momentum p_mathrm {T}^{ell ell } (ell =e,mu ) and of the angular variable phi ^{*}_{eta } distributions of Drell–Yan lepton pairs in a mass range of 66–116 GeV. The analysis uses data from 36.1 fb^{-1} of proton–proton collisions at a centre-of-mass energy of sqrt{s}=13,TeV collected by the ATLAS experiment at the LHC in 2015 and 2016. Measurements in electron-pair and muon-pair final states are performed in the same fiducial volumes, corrected for detector effects, and combined. Compared to previous measurements in proton–proton collisions at sqrt{s}=7 and 8,TeV, these new measurements probe perturbative QCD at a higher centre-of-mass energy with a different composition of initial states. They reach a precision of 0.2% for the normalized spectra at low values of p_mathrm {T}^{ell ell }. The data are compared with different QCD predictions, where it is found that predictions based on resummation approaches can describe the full spectrum within uncertainties.

Investigation of some nuclear structure properties of213Bi,201Tl,188Re,186Re,133Xe,131I,125I,123I,111In,94Tc,90Y,67Ga,67Cu,62Cu,61Cu,55Co, and48Vnuclei used in SPECT in axial deformation

The present work mainly purposed to investigate significant nuclear structure properties nuclei used in single photon emission computed tomography (SPECT), in addition to ground state nuclear properties such as the binding energy per particle, the root mean square (rms) charge, and proton and neutron radii. Besides, we calculated the neutron skin thicknesses (NST), the proton, neutron quadrupole moments ($Q_{P}, Q_{N})$, quadrupole deformation parameter ($\beta_{2})$, and the proton and neutron pairing energies ($P_{P}, P_{N})$ to determine shapes and deformations of SPECT nuclei including odd-odd or odd-even/even-odd nuclei in axial symmetry for Skyrme and Gogny interactions. To analyze the accuracy of the calculated results, the calculated results were compared with available experimental and the theoretical finite-range liquid-drop model (FRDM), and discussed for 12 different force interactions. Notably, the results provide thorough nuclear data to the literature for deformed nuclei of SPECT.