scholarly journals The challenge of monochromatization

2021 ◽  
Vol 137 (1) ◽  
Author(s):  
Angeles Faus-Golfe ◽  
Marco Alan Valdivia Garcia ◽  
Frank Zimmermann
Keyword(s):  
Yukawa Coupling ◽  
Collision Energy ◽  
Opposite Sign ◽  
Center Of Mass ◽  
Resonance Curve ◽  
Energy Spread ◽  
Interaction Point ◽  
Horizontal Dispersion ◽  
Self Consistent ◽  
Colliding Beams

AbstractThe FCC-ee could measure the electron Yukawa coupling in a dedicated run at $$\sim $$ ∼ 125 GeV collision energy, provided that the center-of-mass (CM) energy spread can be reduced by means of monochromatization, e.g., through introducing nonzero horizontal dispersion of opposite sign at the interaction point (IP), for the two colliding beams. If the IP dispersion is nonzero, beamstrahlung blows up the horizontal emittance, and self-consistent IP parameters need to be determined. Two configurations are being studied. The first uses crab cavities to establish effective head-on collisions. The second configuration maintains the standard FCC-ee crossing angle, which, together with the IP dispersion, introduces a correlation between the local collision energy and the longitudinal location inside the detector, thereby allowing for an integrated scan of the Higgs resonance curve. We compare both approaches.

THE STEREODYNAMICS STUDY OF THE C(3P) + OH (X2 Π) → CO(X1Σ+) + H(2S) REACTION

2010 ◽  
Vol 09 (05) ◽  
pp. 935-943 ◽  
Author(s):  
PENG SONG ◽  
YONG-HUA ZHU ◽  
JIAN-YONG LIU ◽  
FENG-CAI MA
Keyword(s):  
Angular Momentum ◽  
Cross Sections ◽  
Collision Energy ◽  
Energy Surface ◽  
Center Of Mass ◽  
Title Reaction ◽  
High Collision Energy ◽  
Dependency Relationship ◽  
Energy Dependency ◽  
Mass Frame

The stereodynamics of the title reaction on the ground electronic state X2A' potential energy surface (PES)1 has been studied using the quasiclassical trajectory (QCT) method. The commonly used polarization-dependent differential cross-sections (PDDCSs) of the product and the angular momentum alignment distribution, P(θr) and P(Φr), are generated in the center-of-mass frame using QCT method to gain insight of the alignment and orientation of the product molecules. Influence of collision energy on the stereodynamics is shown and discussed. The results reveal that the distribution of P(θr) and P(Φr) is sensitive to collision energy. The PDDCSs exhibit different collision energy dependency relationship at low and high collision energy ranges.

RECOMBINATION OF OPPOSITELY CHARGED AQUEOUS CLUSTER IONS USING ELECTROSTATICALLY MERGED ION BEAMS

1996 ◽  
Vol 03 (01) ◽  
pp. 655-660 ◽  
Author(s):  
B. PLASTRIDGE ◽  
K.A. COWEN ◽  
D.A. WOOD ◽  
M.H. COHEN ◽  
J.V. COE
Keyword(s):  
Rate Constants ◽  
Cluster Size ◽  
Collision Energy ◽  
Relative Rate ◽  
Center Of Mass ◽  
Cluster Ions ◽  
Charged Cluster ◽  
Relative Rate Constants ◽  
Oppositely Charged ◽  
Electrostatic Quadrupole

A new method for studying cluster-cluster interactions is introduced which involves merging mass-selected beams of oppositely charged cluster ions with an electrostatic quadrupole deflector. Recombination is monitored by measuring the rate of fast neutral production. Relative rate constants have been measured for the reaction of H 3O+( H 2 O )n+ OH −( H 2 O )m as a function of cluster size (m=n=0–3), which display a pronounced enhancement with clustering. Relative rate constants have also been measured as a function of center-of-mass collision energy for a heavily clustered reaction (n=3, m=3) and a lightly clustered reaction (n=1, m=0) revealing that clustering produces a dramatic change in the reaction mechanism.

scholarly journals Possible signals of two QCD phase transitions at NICA-FAIR energies

2019 ◽  
Vol 204 ◽  
pp. 03001 ◽  
Author(s):  
K. A. Bugaev ◽  
A. I. Ivanytskyi ◽  
V. V. Sagun ◽  
B. E. Grinyuk ◽  
D. O. Savchenko ◽  
...  
Keyword(s):  
Phase Diagram ◽  
Phase Transitions ◽  
Collision Energy ◽  
Center Of Mass ◽  
Solvable Model ◽  
Exactly Solvable Model ◽  
Qcd Phase Diagram ◽  
Exactly Solvable ◽  
Experimental Findings ◽  
Chemical Freeze

The chemical freeze-out irregularities found with the most advanced hadron resonance gas model and possible signals of two QCD phase transitions are discussed. We have found that the center-of-mass collision energy range of tricritical endpoint of QCD phase diagram is [9; 9.2] GeV which is consistent both with the QCD inspired exactly solvable model and experimental findings.

Molecular Dynamics Simulations of Hypervelocity Buckminsterfullerene Collisions

1994 ◽  
Vol 359 ◽  
Author(s):  
D.H. Robertson ◽  
D.W. Brenner ◽  
C.T. White
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Collision Energy ◽  
Center Of Mass ◽  
High Energy ◽  
Translational Energy ◽  
Inelastic Behavior ◽  
Fusion Probability ◽  
High Energy Collisions ◽  
Dynamics Simulations

ABSTRACTMolecular dynamics simulations of high-energy collisions between various combinations of C60 and C70 fullerenes were performed to calculate the threshold for molecular fusion of these clusters as a function of the center-of-mass collision energy. For collision energies below 90 eV, only non-reacting collisions occurred with no observation of any fusion. However, at higher collision energies molecular fusion of the colliding clusters was observed with the fusion probability approaching 1 by 160 eV collision energy. The non-fusing, rebounding collisions showed deeply inelastic behavior with the loss of translational energy to internal energy varying from 50 to 70 percent.

Center of mass energy for charged particles in regular black holes

2014 ◽  
Vol 92 (6) ◽  
pp. 497-503 ◽  
Author(s):  
M. Sharif ◽  
Nida Haider
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Collision Energy ◽  
Center Of Mass ◽  
Charged Particles ◽  
Charge Ratio ◽  
Regular Space ◽  
Mass Energy ◽  
Regular Black Hole ◽  
Center Of Mass Energy

This paper is devoted to study the acceleration and collision of charged particles in a general regular space–time. Using angular momentum, energy, and components of four-velocity, we explore the effect of charged particles on the center of mass energy. It is found that the collision energy of charged particles (independent of both singularity as well as horizon) is greater than that of uncharged particles. This depends not only on the mass to charge ratio of the black hole but also on the charge of the particle. Finally, we evaluate the collision energy of charged particles for a regular black hole, a particular example.

scholarly journals Azimuthally Integrated HBT Parameters for Charged Pions in Nucleus-Nucleus Interactions versus Collision Energy

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
V. A. Okorokov
Keyword(s):  
Energy Dependence ◽  
Reasonable Agreement ◽  
Collision Energy ◽  
Center Of Mass ◽  
Nucleon Nucleon ◽  
Emission Region ◽  
Smooth Approximation ◽  
Nuclear Collisions ◽  
Charged Pions ◽  
Measurement Uncertainties

The energy dependence of spatiotemporal characteristics of particle emission region is studied for charged pions produced in nuclear collisions. No dramatic change is observed for the HBT parameters with increasing of the center-of-mass (c.m.) energy per nucleon-nucleon pair,sNN, forsNNof a few GeV to a few TeV. The emission duration is obtained to be almost independent of the c.m. energy within the measurement uncertainties. The analytic function is suggested for a smooth approximation of the energy dependence of the main HBT parameters. The fits demonstrate reasonable agreement with the experimental data. Predictions are made for future LHC and FCC experiments.

scholarly journals Separate freeze-out of strange particles and the quark-hadron phase transition

2018 ◽  
Vol 182 ◽  
pp. 02057
Author(s):  
K. Bugaev ◽  
V. Sagun ◽  
A. Ivanytskyi ◽  
E. Nikonov ◽  
J. Cleymans ◽  
...  
Keyword(s):  
Collision Energy ◽  
Center Of Mass ◽  
Suppression Factor ◽  
Hadron Phase ◽  
Hadron Multiplicity ◽  
Strange Particles ◽  
The One ◽  
Baryonic Charge ◽  
Chemical Freeze ◽  
Freeze Out

The scenario of the independent chemical freeze-outs for strange and nonstrange particles is discussed. Within such a scenario an apparent in-equilibrium of strangeness is naturally explained by a separation of chemical freeze-out of strange hadrons from the one of non-strange hadrons, which, nevertheless, are connected by the conservation laws of entropy, baryonic charge and third isospin projection. An interplay between the separate freeze-out of strangeness and its residual non-equilibrium is studied within an elaborate version of the hadron resonance gas model. The developed model enables us to perform a high-quality fit of the hadron multiplicity ratios measured at AGS, SPS and RHIC with an overall fit quality ϰ2/dof = 0:93. A special attention is paid to a description of the Strangeness Horn and to the well-known problem of selective suppression of Δ- and ж hyperons. It is remarkable that for all collision energies the strangeness suppression factor γs is about 1 within the error bars. The only exception is found in the vicinity of the center-of-mass collision energy 7.6 GeV, at which a residual enhancement of strangeness of about 20 % is observed.

scholarly journals Chemical Potentials of Light Flavor Quarks from Yield Ratios of Negative to Positive Particles in Au+Au Collisions at RHIC

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ya-Qin Gao ◽  
Hai-Ling Lao ◽  
Fu-Hu Liu
Keyword(s):  
Transverse Momentum ◽  
Collision Energy ◽  
Center Of Mass ◽  
Star Collaboration ◽  
Strange Quarks ◽  
Center Of Mass Energy ◽  
Chemical Potentials ◽  
Momentum Spectra ◽  
200 Gev ◽  
Transverse Momentum Spectra

The transverse momentum spectra of π-, π+, K-, K+, p¯, and p produced in Au+Au collisions at center-of-mass energy sNN=7.7, 11.5, 19.6, 27, 39, 62.4, 130, and 200 GeV are analyzed in the framework of a multisource thermal model. The experimental data measured at midrapidity by the STAR Collaboration are fitted by the (two-component) standard distribution. The effective temperature of emission source increases obviously with the increase of the particle mass and the collision energy. At different collision energies, the chemical potentials of up, down, and strange quarks are obtained from the antiparticle to particle yield ratios in given transverse momentum ranges available in experiments. With the increase of logarithmic collision energy, the chemical potentials of light flavor quarks decrease exponentially.

QUASICLASSICAL TRAJECTORY STUDY OF STEREODYNAMICS FOR THE REACTIONS Li+HF/DF/TF

2013 ◽  
Vol 12 (03) ◽  
pp. 1350008
Author(s):  
JIE CHENG ◽  
XIAN-FANG YUE
Keyword(s):  
Angular Momentum ◽  
Cross Sections ◽  
Collision Energy ◽  
Energy Surface ◽  
Center Of Mass ◽  
Angular Distributions ◽  
Direct Reaction ◽  
Generalized Polarization ◽  
State 1 ◽  
Rotational Angular Momentum

Stereodynamics of the reaction Li + HF (v = 0,j = 0) → LiF + H and its isotopic variants on the ground electronic state (12A′) potential energy surface (PES) are studied by employing the quasiclassical trajectory (QCT) method. At a collision energy of 2.2 kcal/mol, product rotational angular momentum distributions, P(θr) and P(ϕr), are calculated in the center-of-mass (CM) frame. The results demonstrate that the product rotational angular momentum j′ is not only aligned along the direction perpendicular to the reagent relative velocity vector k, but also oriented along the negative y-axis. The four generalized polarization-dependent differential cross sections (PDDCSs) are also computed. The PDDCS00 distribution shows a sideways scattering for the reaction Li + HF and a strongly backward scattering for the reaction Li + DF . However, it displays both the forward and backward scatterings for the reaction Li + TF . These features demonstrate that the Li + HF and Li + DF reactions proceed predominantly through the direct reaction mechanism. However, the Li + TF reaction undergoes both the direct and indirect reaction mechanisms. The PDDCS21- distribution indicates that the product angular distributions are anisotropic.

scholarly journals THE EFFECT OF SPATIAL CURVATURE ON CLASSICAL AND QUANTUM STRINGS

1996 ◽  
Vol 11 (21) ◽  
pp. 4005-4030 ◽  
Author(s):  
A.L. LARSEN ◽  
N. SÁNCHEZ
Keyword(s):  
Center Of Mass ◽  
Elliptic Functions ◽  
Space Time ◽  
Einstein Equations ◽  
Back Reaction ◽  
Level Spacing ◽  
Spatial Curvature ◽  
Curvature Index ◽  
Self Consistent ◽  
Consistent Solution

We study the effects of spatial curvature on classical and quantum string dynamics. We find the general solution of the circular string motion in static Robertson–Walker space-times with closed or open sections. This is given closely and completely in terms of elliptic functions. The physical properties, string length, energy and pressure are computed and analyzed. We find the back-reaction effect of these strings on the space-time: the self-consistent solution to the Einstein equations is a spatially closed (K>0) space-time with a selected value of the curvature index K (the scale factor is normalized to unity). No self-consistent solutions with K≤0 exist. We semiclassically quantize the circular strings and find the mass m in each case. For K>0, the very massive strings, oscillating on the full hypersphere, have m2~Kn2(n∈N0)independent of α' and the level spacing grows with n, while the strings oscillating on one hemisphere (without crossing the equator) have m2α′~n and a finite number of states N~1/Kα′. For K<0, there are infinitely many string states with masses m log m ~ n, i.e. the level spacing grows slower than n. The stationary string solutions as well as the generic string fluctuations around the center of mass are also found and analyzed in closed form.

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