Hi, Peter, Isn't the condition K^+ - K^- ~ Lambda - Lambda_bar at each rapidity coming from local strangeness conservation rather than chemical equilibrium ? If we assume strangeness is only carried by lambdas and kaons and conserved, s - s_bar = (K^- + Lambda) - (K^+ + Lambda_bar) = 0 K^+ - K^- = Lambda - Lambda_bar, which doesn't explicitly need chemical equilibrium. JH Peter Christiansen wrote: > Dear Michael, > > I have tried to play with these things from another angle once > (following chemical ideas of BRAHMS, you, and others) that might be > useful. If you would have chemical equilibration at each rapidity you > would expect: > K^+-K^- ~ Lambda - Lambda-bar > > If I look at NA49 data this does not seem so bad an estimate, see > attached plot (there is one of the data sets where the centralities are > not the same for Ks and Lambdas as I remember). > > It might not help you to get p/Lambda (or the pT dependence - I think > Flemming has done some work on this), but it might give some cross > check:-) > > Cheers, > Peter > > On Wed, 2009-08-12 at 17:15 -0500, Michael Murray wrote: > >> Dear Casper, >> BRAHMS has found that the strange chemical >> potential m_s = 0.28 +- 0.04 * m_q >> Since lambda is like a proton that has an up quark changed to a >> strange quark then lambda/p is proportional to exp (mu_s - mu_q) = >> exp (0.72 mu_q) or (pbar/p)**0.12 >> >> Given the change of pbar/p from 0.75 to 0.23 from y=0 to y=3.1 I find >> that the lambda/proton ratio should decrease by a factor of 0.86+-0.02 >> >> The antilambda/antiproton ratio should INCREASE by this factor. >> >> This seems like a reasonable estimate for the overall change in the >> ratio. I will work on the Pt dependence next. >> Michael >> >> >> >> _______________________________________________ >> Brahms-l mailing list >> Brahms-l_at_lists.bnl.gov >> https://lists.bnl.gov/mailman/listinfo/brahms-l >> >> >> >> ------------------------------------------------------------------------ >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> Brahms-l mailing list >> Brahms-l_at_lists.bnl.gov >> https://lists.bnl.gov/mailman/listinfo/brahms-l >> _______________________________________________ Brahms-l mailing list Brahms-l_at_lists.bnl.gov https://lists.bnl.gov/mailman/listinfo/brahms-lReceived on Thu Aug 13 2009 - 12:50:05 EDT
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