Electro not-so-weak interactions

Electro not-so-weak interactions Paolo Ciafaloni INFN – Sezione di Lecce

In this talk • What is the asymptotic behaviour of cross sections • What is the relevance for LHC, LC? E>>Mw,Mz,mt~M~100 GeV Standard Model of EW int. Only relevant scale for the process

How the story begins on a day of last century......

RGE 1 loop • Why not RGE-driven? • ∆σ≈10 %@ TeV  higher orders • LEP: leading terms in mtⁿ, (log E)ⁿ

P. Ciafaloni, D. Comelli ‘98 At high energies Z,W similar to g,  k p p+k • Singularity for k →0, k~ p  log2μ(EW: μ→ M) • Asymptotic behaviour dictated by IR (not UV) • Emission probability ~ log2(E/M) (non )

Asymptotic expansion IR UV LHC, LC LEP n loops: LL NLL NNLL • Unusual situation! QED, QCD (α log)ⁿ • Dependence on IR cutoff M for any E

2 fermions→2 fermions B. Jantzen V.A. Smirnov hep-ph/0603133 LC 2 loops SU(2)

S. Moretti, M. Nolten, D. Ross, hep-ph/0603083 LHC

Inclusive observables “hard”: E > 1 TeV P P 2 j + X W,Z X “soft”: 100 GeV < E << 1 TeV

BN: “IR safe” observables do not exist! QED BN: EW BN: all observables, even including W, Z emission depend on P. Ciafaloni M. Ciafaloni D. Comelli

Noncancellation mechanism n • QCD confines  color average infrared safe ! • EW: average over e ,  senseless • Symmetry breaking BN M. Ciafaloni, P. Ciafaloni, D. Comelli 2000-2005

LC E asymptotically

P. Ciafaloni M. Ciafaloni D. Comelli ‘05 A 1 TeV 14 %8 %

U. Baur (2006)

as a function of “inclusivity” x

Heavy quarks production P. Ciafaloni, D. Comelli ’06

Conclusions Why don’t we begin taking seriously into account weak gauge bosons emissions at ILC, LHC?

Conclusions • High energy EW dominated by log^2(E) of IR origin • W,Z emission HAVE to be considered for ILC but also for LHC • Final prediction (sign) very much dependent on observable definition

Precisione < 1%  higher orders 1 loop, leading 2 loops, risommazioni  predizioni sotto controllo Precisione inferiore Non necessariamente dominato da QCD Osservabili inclusive  effetti spettacolari Correzioni elettrodeboli alla scala del TeV - Dominate da struttura IR, non UV - O(20 %) a 1 TeV LC LHC

Electro not-so-weak interactions

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