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Test of the Universal Rise of Total Cross Sections at Super-high Energies and LHC

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### Test of the Universal Rise of Total Cross Sections atSuper-high Energies and LHC

Keiji IGI

RIKEN, Japan

August 10, 2007

Summer Institute 2007, Fuji-Yoshida

In collaboration with Muneyuki ISHIDA

K.Igi and M.Ishida: hep-ph/0703038(to be published in Euro.Phys. J. C)

Phys.Rev.D66 (2002) 034023; Phys.Lett. B 622 (2005) 286; Prg.Theor.Phys. 116 (2006) 1097

Introduction

- As is well-known as Froissart-Martin unitarity bound, Increase of tot. cross section σtot is

at most log2ν:

- However, before 2002, it was not known whether this increase is described by logνor log2ν in πp scattering.
- Therefore we have proposed to use rich inf. of σtot(πp) in accel. energy reg. through FESR.

log2ν preferred

- This preference has also been confirmed by Block,Halzen’04,’05.

For , we searched for the simultaneous best fit of

and up to some energy(e.g.,ISR) in terms of high-energy parameters constrained by FESR.

- We then predicted and in the LHC and high-energy cosmic-ray regions.

It is very important to notice that energy range of predcted

several orders of mag. larger than energy region of input.

p=70GeV|

|ISR (p=2100GeV)

| LHC(ECM=14TeV)

(c) : High energy region

(a) : All region

Fig.1. Predictions for and

The fit is done for data up to ISR

as shown by the arrow.

| LHC(ECM=14TeV)

(d)

Universal rise of σtot?

Statement :

Rise of σtot at super-high energies is universal

by COMPETE collab.,that is,

the coefficient B in front of log2(s/s0) term is universal

for all processes with N and γ targets

(by COMPETE collab.)

Assuming universal B,σtot is fitted by log2ν for various processes:

pp, Σ-p, πp, Kp, γp

ν: energy in lab.system

Result in PDG’06 by COMPETE

B is taken to be universal from the beginning.

σπN～ σNN～・・・assumed at super-high energies!

Analysis guided strongly by theory !

Particle Data Group 2006

- stated that models with asymp. terms works much better than models with or

was confirmed by [Igi,Ishida’02,’05],

[Block,Halzen’04,’05].

- “Boththese refs., however, questioned the statement (by [COMPETE Collab.]) on the universality of the coeff. of the log2(s/s0).The two refs. give different predictions at superhigh energies:

σπN > σNN [Igi,Ishida’02,’05]

σπN～ 2/3 σNN [Block,Halzen’04,’05]”

Purpose of my talk

is to investigate the value of

Bfor pp, pp, π±p, K±p

in order to test the universality of B

(the coeff. of log2(s/s0) terms)

with no theoretical bias.

The σtot and ρ ratio(Re f/Im f) are fitted simultaneously, using FESR as a constraint.

ー

FESR

- We have obtainedFESR in the spirit of P’ sum rule:

1962

unphysical regions

This gives directly a constraint for πp scattering:

For pp, Kp scatterings, problem of unphysical region. Considering N=N1 and N=N2, taking the difference,

between these two relations, we obtain

FESR

- Integral of cross sections are estimated with sufficient accuracy (less than 1%).
- We regard these rels. as exact constraints between high energy parameters:

βP’, c0, c1, c2

The general approach

- The σtot (k > 20GeV) and ρ(k > 5GeV) are fitted simultly. for resp. processes:

- High-energy params. c2,c1,c0,βP’,βV are treated as process-dependent.(F(+)(0) : additional param.)
- FESR used as a constraint βP’=βP’(c2,c1,c0)
- # of fitting params. is 5 for resp. processes.
- COMPETEB = (4π / m2 ) c2 ; m = Mp, μ, mK
- Check the universality of B parameter.

The χ2 in the best fit

- ρ(pp) Fajardo80, Belletini65 removed.
- ρ(π-p) Apokin76,75,78 removed.
- Reduced χ2 less than unity both for total χ2 and respective χ2.

Fits are successful .

The values of B parameters(mb)

Bpp is somewhat smaller than Bπp, but consistent within two standard deviation. Cons.with BKp(large error).

Conclusions

- Present experimental data are consistent with the universality of B, that is, the universal rise of the σtot in super-high energies.
- Especially, σπＮ～2/3 σＮＮ[Block,Halzen’05], which seems natural from quark model, is disfavoured.

Comparison with Other Groups

- Our Bpp=0.289(23)mb (αP’=0.5 case) is consistent with B=0.308(10) by COMPETE, obtained by assuming universality.
- Our Bpp is also consistent with

0.2817(64) or 0.2792(59)mb byBlock,Halzen, 0.263(23), 0.249(40)sys(23)stat byIgi,Ishida’06,’05

- Our Bpp is located between the results by COMPETE’02 and Block,Halzen’05.

Our Prediction at LHC(14TeV)

- consistent with our previous predictions:

σtot =107.1±2.6mb, ρ=0.127±0.004 in’06

σtot=106.3±5.1syst±2.4statmb,

ρ=0.126±0.007syst±0.004stat , in ‘05

- Located between predictions by other two groups: COMPETE’02 and Block,Halzen’05

Our pred.contradicts with Donnachie-L. σ=127mb

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