Search for a low-mass Higgs boson (A0A^0) at BABAR

The BABAR Collaboration has performed three searches for a light Higgs boson, $A^0$, in radiative Upsilon ($\Upsilon$) decays: $\Upsilon(3S)\to\gamma A^0$, $A^0\to\tau^+\tau^-$; $\Upsilon(nS)\to\gamma A^0$, $A^0\to\mu^+\mu^-$ ($n=2,3$); and $\Upsilon(3S)\to\gamma A^0$, $A^0\to$ invisible. Such a Higgs boson ($A^0$) appears in the Next-to-Minimal Supersymmetric extensions of the Standard Model, where a light CP-odd Higgs boson couples strongly to $b$-quarks. The searches are based on data samples that consist of $122\times 10^6$ $\Upsilon(3S)$ and $99\times 10^6$ $\Upsilon(2S)$ decays, collected by the BABAR detector at the SLAC National Accelerator Laboratory. The searches reveal no evidence for an $A^0$, and product of branching fractions upper limits, at 90% C.L., of $(1.5-16)\times 10^{-5}$, $(0.44-44)\times 10^{-6}$, and $(0.7-31)\times 10^{-6}$ were obtained for these searches, respectively. Also, we set the upper limits ${\mathcal {B}}(\eta_b\to\tau^+\tau^-)<8$ and ${\mathcal {B}}(\eta_b\to\mu^+\mu^-)<0.9$.Comment: To appear in the proceedings of the 2009 Europhysics Conference on High Energy Physics, July 16-22, 2009, Krakow, Polan

Studies of charmonium-like states at BABAR

Several charmonium-like states above $D\bar{D}$ threshold have been discovered at the Belle and BABAR B-factories. Some of these states are produced via Initial State Radiation (e.g. Y(4260) and Y(4350)), and some are observed in B-meson decays (e.g. X(3872), and Y(3940)). The Belle observations of the enhancements in the $\psi(2S)\pi^-$ and $\chi_{c1}\pi^-$, i.e. the Z(4430)-, Z_1(4050)-, and Z_2(4250)-, have generated a great deal of interest, because such states must have minimum quark content $(c\bar{c}d\bar{u})$, i.e. these are candidate four-quark state. The BABAR Collaboration does not confirm the existinence of the $Z(4430)^-$.Comment: To appear in the proceedings of the 2009 Europhysics Conference on High Energy Physics, July 16-22, 2009, Krakow, Polan

Evidence for a narrow baryonic state decaying to K0Sp and KOSp in deep inelastic scattering at HERA

A resonance search has been made in the K0Sp and KOSp invariant-mass spectrum measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb−1. The search was performed in the central rapidity region of inclusive deep inelastic scattering at an ep centre-of-mass energy of 300–318 GeV for exchanged photon virtuality, Q2, above 1 GeV2. Recent results from fixed-target experiments give evidence for a narrow baryon resonance decaying to K+n and K0Sp, interpreted as a pentaquark. The results presented here support the existence of such state, with a mass of 1521.5±1.5(stat.)+2.8−1.7(syst.) MeV and a Gaussian width consistent with the experimental resolution of 2 MeV. The signal is visible at high Q2 and, for Q2>20 GeV2, contains 221±48 events. The probability of a similar signal anywhere in the range 1500–1560 MeV arising from fluctuations of the background is below 6×10−5

Search for Low-Mass Dark-Sector Higgs Bosons

Recent astrophysical and terrestrial experiments have motivated the proposal of a dark sector with GeV-scale gauge boson force carriers and new Higgs bosons. We present a search for a dark Higgs boson using 516  fb^(-1) of data collected with the BABAR detector. We do not observe a significant signal and we set 90% confidence level upper limits on the product of the standard model-dark-sector mixing angle and the dark-sector coupling constant