rpp2010-rev-eta1440 - – 1– THE (1405 (1475 f 1(1420...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: – 1– THE η (1405), η (1475), f 1 (1420), AND f 1 (1510) Revised February 2010 by C. Amsler (Z¨urich) and A. Masoni (INFN Cagliari). The first observation of the η (1440) was made in p p anni- hilation at rest into η (1440) π + π − , η (1440) → K Kπ [1]. This state was reported to decay through a (980) π and K ∗ (892) K with roughly equal contributions. The η (1440) was also ob- served in radiative J/ψ (1 S ) decay into K Kπ [2–4] and γρ [5]. There is now evidence for the existence of two pseudoscalars in this mass region, the η (1405) and η (1475). The former decays mainly through a (980) π (or direct K Kπ ) and the latter mainly to K ∗ (892) K . The simultaneous observation of two pseudoscalars is re- ported in three production mechanisms: π − p [6,7]; radiative J/ψ (1 S ) decay [8,9]; and pp annihilation at rest [11–14]. All of them give values for the masses, widths, and decay modes in reasonable agreement. However, Ref. [9] favors a state decay- ing into K ∗ (892) K at a lower mass than the state decaying into a (980) π , although agreement with MARK-III is not excluded. In J/ψ (1 S ) radiative decay, the η (1405) decays into K Kπ through a (980) π , and hence a signal is also expected in the ηππ mass spectrum. This was indeed observed by MARK III in ηπ + π − [15], which reports a mass of 1400 MeV, in line with the existence of the η (1405) decaying into a (980) π . BES [10] reports an enhancement in K + K − π around 1.44 GeV in J/ψ (1 S ) decay, recoiling against an ω (but not a φ ) without re- solving the presence of two states nor performing a spin-parity analysis, due to low statistics. This state could also be the f 1 (1420) (see below). The η (1405) is also observed in pp annihilation at rest into ηπ + π − π π , where it decays into ηππ [16]. The intermedi- ate a (980) π accounts for roughly half of the ηππ signal, in agreement with MARK III [15] and DM2 [4]. The η (1295) has been observed by four π − p experiments [7,17–19], and evidence is reported in pp annihilation [23–25]. In J/ψ (1 S ) radiative decay, an η (1295) signal is evident in the − + ηππ wave of the DM2 data [9]. Also BaBar [20] reports evidence for a signal around 1295 MeV in B decays into ηππK . CITATION: K. Nakamura et al. (Particle Data Group), JPG 37 , 075021 (2010) (URL: http://pdg.lbl.gov) July 30, 2010 14:34 – 2– However, the existence of the η (1295) is questioned in Refs. [21] and [22]. The authors claim a single pseudoscalar meson in the 1400 MeV region. This conclusion is based on properties of the wave functions in the 3 P model (and on an unpublished analysis of the annihilation ¯ pp → 4 πη ). The pseudoscalar signal around 1400 MeV is then attributed to the first radial excitation of the η ....
View Full Document

This note was uploaded on 06/07/2011 for the course PHYS 4132 taught by Professor Kutter during the Spring '11 term at University of Florida.

Page1 / 6

rpp2010-rev-eta1440 - – 1– THE (1405 (1475 f 1(1420...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online