Re: ratios 3.04

From: Dieter Rohrich (dieter@fi.uib.no)
Date: Mon Jul 08 2002 - 04:32:29 EDT

  • Next message: Zbigniew Majka: "Re: version 3.04"

    Dear Jens Jorgen,
    
    since none of my major comments have been taken into account in the new
    version, I have to repeat them again and I am serious about them.
    The following comments are not cosmetical. The main message of our paper
    is fig. 3, so we should make sure that the data points are solid and
    errors are understood instead of getting lost in cracker-barrel philosophy
    about equilibrium and plateaus. I do not agree with you that the current
    version can be published, because some statements we make are ridiculous
    and only show our ignorance. 
    
    
    1. Nuclear transparencey and Bjorken scenario:
    
    Nuclear transparency will be discussed in length in our stopping paper 
    (and that's the appropriate place to do it), and
    plateaus we have discussed in our dn/deta publications.
    
    This paper is about particle ratios as a function of rapidity,
    which are an input to statistical models of particle
    production/hadronization and an essential constraint on dynamical models 
    and whether the ratios are sensitive to the partonic phase. 
    
    The Bjorken scenario can be mentioned in the text, but
    NOT in the abstract and NOT in the summary because it is irrelevant.
    
    
    2. Statistical models and their thermal interpretation:
    
    We are violating all basic assumptions of statistical models
    when plotting thermal predictions on top of fig.4, i.e. we are treating
    the ratios at different rapidities as completely independent
    systems. OK, we can do this and we should, but drawing conclusions like 
    u_s = 1/4 x u_q is ridiculous. And the statements about chemical (and even
    local) equilibrium show that we have missed the scientific discussion
    about equilibration vs dynamics during the last 3 years.
    The conclusion I would draw from Fig.4 (the fact that statistical models
    predict the observed ratios) is that a thermal interpretation of these
    models is questionable - in contrast to the equilibrium idea.
    
    
    Here the comments in detail:
     
    Abstract
    
    second sentence:
    remove "and consistent with significant significant nuclear transparency"
     
    third sentence:
    remove "locally equilibrated sources and a"
    If we use statistical models AND interprete the parameters as T and 
    mu_b, we implicitely assume chemical equilibrium. 
    One can NOT deduce chemical equilibrium from the fact that statistical
    models describe the measured ratios. Omit this sentence.
    
    Page 1:
    
    4. para.:
    insert "net" into "This behaviour supports ..... of a nearly 
    NET baryon-free zone at ...." 
    
    
    Page 4:
    
    first column, 1. para., last s.:
    remove "This is consistent with the onset of the boost invariant
    plateau around midrapidity proposed by Bjorken."
    
    1. col., 2. para., first s.:
    The statement "The measured set of particle ratios as a function of
    rapidity also lends itself to an analysis in terms of a model ..."
    Wrong. Midrapidity ratios or 4pi ratios are input to thermal models.
    These models have no concept about rapidity.
    Remove "as a function of rapidity". 
    
    
    Fig.4:
    replace "shows the relation K-/K+ = (pbar/p)**(1/4)" 
    with "shows a fit to the relation K-/K+ = (pbar/p)**alpha; alpha = 0.24".
    We have no physics argument for the (1/4) relation.
    
    
    second column, second para.:
    replace "can be expressed by a power law ..."
    with
    "can be fitted to a power law  K-/K+ = (pbar/p)**alpha; alpha = 0.24"
    See comment above. A fit to a (1/4) power law without a physics
    motivation is useless.
    Remove "Comparison if the two relations gives u_s = 1/4 x u_q".
    
    
    Page 5
    
    1. para., 1. s.:
    This statement is wrong:
    "Within the framework of the statistcal model,
    Fig. 4 suggests, that the particle source corresponding to the
    different rapidity regions sampled in our experiments are all in local
    chemical equilibrium with strangeness conservation"
    No. By plotting the statistical model on top of our data and by 
    chosing a thermal interpretation of the parameters we assume
    the above. Rephrase the sentence. Again, from the fact that statistical
    models describe the measured ratios, one can NOT deduce chemical
    equilibrium.
    
    second para.:
    remove "suggesting the existence of a boost invariant midrapidity
    plateau dominated by particle production from the color field."
    We have no evidence for e.g. boost invariance, and we do not measure
    particle ratios to discover/prove/disprove boost invariant plateaus.
    



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