pp elastic scattering at LHC energies

Kohara, Anderson Kendi; Ferreira, E.; Kodama, Takeshi

doi:10.1140/epjc/s10052-014-3175-x

Cited by 49 publications

(122 citation statements)

References 38 publications

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“…This constraint has been confirmed in previous analyses at LHC and lower energies [7,8], with the conclusion that the position of the first zero of the real part behaves like |t R | = A + 1/(c 0 + c 1 log s + c 2 log 2 s).…”

Section: Lhc Experiments In Elastic Pp Scatteringsupporting

confidence: 79%

“…Assuming σ ∼ log 2 s at high energies, dispersion relations give ρ ∼ π/ log s, and we know that the position of the first real zero [8] behaves like |t R | A + 1/(c 0 + c 1 log s + c 2 log 2 s). From Eq.…”

Section: Discussionmentioning

confidence: 98%

“…• (I) all six parameters are free; • (II) fixing ρ at 0.14, as suggested by dispersion relations; • (III) fixing μ I from the expected positions of imaginary zero [7,8] and dip in dσ/dt; • (IV) fixing simultaneously ρ and μ I at the above values.…”

Section: Discussionmentioning

confidence: 99%

“…According to analyses and models of pp and pp scattering at high energies [7][8][9][10][11][12][13][14][15][16], including full-t ranges, the imaginary part has a zero near the marked dip observed in dσ/dt at about 0.4-0.6 GeV 2 , while the real part starts positive at t = 0, has a zero for small |t| (Martin's theorem), and a second zero after the dip. The descriptions of the models differ for higher |t| about the position of this second real zero and about the existence of further imaginary or real zeros.…”

Section: Lhc Experiments In Elastic Pp Scatteringmentioning

confidence: 99%

“…With Condition (III) we fix μ I according with the expected positions of the imaginary zero and dip in dσ/dt [7,8], and let ρ free. This is successful, as ρ results about the same or improved with respect to Condition (I) (all parameters free), except for A7, as expected.…”

Section: Summary Of the Analysismentioning

confidence: 99%

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Elastic amplitudes studied with the LHC measurements at 7 and 8 TeV

et al. 2017

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Recent measurements of the differential cross sections in the forward region of pp elastic scattering at 7 and 8 TeV show the precise form of the t dependence. We present a detailed analysis of these measurements including the structures of the real and imaginary parts of the scattering amplitude. A good description is achieved, confirming in all experiments the existence of a zero in the real part in the forward region close to the origin, in agreement with the prediction of a theorem by Martin, with an important role in the observed form of dσ/dt. A universal value for the position of this zero and regularity in other features of the amplitudes are found, leading to quantitative predictions for the forward elastic scattering at 13 TeV. LHC experiments in elastic pp scatteringWith an enormous gap in the center-of-mass energy with respect to previous data in pp and pp scattering, the Totem and Atlas experimental groups at LHC have recently measured dσ/dt in the forward t ranges at √ s = 7 and 8 TeV [1][2][3][4][5]. These measurements offer a unique opportunity to investigate the behavior of p-p collisions at the highest energies reached in laboratory. A detailed and precise analysis of these data can establish a precious milestone for the understanding of the high energy behavior of p-p interactions. The datasets and their t ranges are listed in Table 1, where we use the obvious notation T7, T8, A7, A8 to specify Totem (T) and Atlas (A) Collaborations and center-of-mass energies 7 and 8 TeV.In order to build a bridge towards theoretical models aiming at the understanding of the dynamics, it is important that the analysis of these LHC data be made with identification of the structures of the individual parts of the complex scattering amplitude. The disentanglement of the two terms in the a e-mail: kendi@if.ufrj.br observed modulus dσ/dt is the crucial task. At each energy, parameterizations must search to exhibit clearly the properties of magnitudes, signs, slopes and zeros of the real and imaginary parts. External support, as dispersion relations and connections with analyses at other energies, gives important clues. The intervention of the electromagnetic interactions must be treated coherently with a proposed analytical form for the nuclear part, and account must be taken of phase of the Coulomb-Nuclear Interference (CNI), which is calculated in Appendix A.In the present work we perform a detailed examination of the data trying to satisfy these requirements. Each part of the amplitude is written with an exponential factor with a slope, multiplying a linear term in t, thus with three parameters. These analytical forms are sufficient to describe the properties of the nuclear parts. The six parameters for each dataset are studied using fits to data with appropriate statistical control. Correlations are studied, and resulting values are proposed for each dataset. Good description of the measurements is obtained, with details in the shape of the forward diffractive peak, exhibiting the zero of the real par...

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Section: Lhc Experiments In Elastic Pp Scatteringsupporting

confidence: 79%

Section: Discussionmentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Lhc Experiments In Elastic Pp Scatteringmentioning

confidence: 99%

Section: Summary Of the Analysismentioning

confidence: 99%

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Elastic amplitudes studied with the LHC measurements at 7 and 8 TeV

et al. 2017

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Exploring central opacity and asymptotic scenarios in elastic hadron scattering

Fagundes¹,

Menon²,

Silva³

2016

Nuclear Physics A

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In the absence of a global description of the experimental data on elastic and soft diffractive scattering from the first principles of QCD, model-independent analyses may provide useful phenomenological insights for the development of the theory in the soft sector. With that in mind, we present an empirical study on the energy dependence of the ratio X between the elastic and total cross sections; a quantity related to the evolution of the hadronic central opacity. The dataset comprises all the experimental information available on proton-proton and antiproton-proton scattering in the c.m energy interval 5 GeV -8 TeV. Generalizing previous works, we discuss four model-independent analytical parameterizations for X, consisting of sigmoid functions composed with elementary functions of the energy and three distinct asymptotic scenarios: either the standard black disk limit or scenarios above or below that limit. Our two main conclusions are the following: (1) although consistent with the experimental data, the black disk does not represent an unique solution; (2) the data reductions favor a semi-transparent scenario, with asymptotic average value for the ratioX = 0.30 ± 0.12. In this case, within the uncertainty, the asymptotic regime may already be reached around 1000 TeV. We present a comparative study of the two scenarios, including predictions for the inelastic channel (diffraction dissociation) and the ratio associated with the total cross-section and the elastic slope. Details on the selection of our empirical ansatz for X and physical aspects related to a change of curvature in this quantity at 80 -100 GeV, indicating the beginning of a saturation effect, are also presented and discussed.

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Comments on high-energy total cross sections in QCD

Giordano

Meggiolaro

2015

Physics Letters B

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We discuss how hadronic total cross sections at high energy depend on the\ud details of QCD, namely on the number of colours $N_c$ and the quark masses. We\ud find that while a "Froissart"-type behaviour $\sigma_{\rm tot}\sim B\log^2s$ is\ud rather general, relying only on the presence of higher-spin stable particles in\ud the spectrum, the value of $B$ depends quite strongly on the quark masses.\ud Moreover, we argue that $B$ is of order ${\cal O}(N_c^0)$ at large $N_c$, and\ud we discuss a bound for $B$ which does not become singular in the $N_f=2$ chiral\ud limit, unlike the Froissart-Lukaszuk-Martin bound

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pp elastic scattering at LHC energies

Cited by 49 publications

References 38 publications

Elastic amplitudes studied with the LHC measurements at 7 and 8 TeV

Elastic amplitudes studied with the LHC measurements at 7 and 8 TeV

Exploring central opacity and asymptotic scenarios in elastic hadron scattering

Comments on high-energy total cross sections in QCD

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