我们在窄Upperdom（3S）共振的辐射衰变中寻找轻希格斯玻色子（A0）的证据：Upperdom（3S）-> gamma A0，其中A0 ->不可见或A0 -> mu+mu-。这样的物体出现在标准模型的扩展中，在标准模型中，一个轻的CP奇希格斯玻色子玻色子自然地与b夸克强烈耦合。我们在PEP II B工厂的BaBar合作收集的1.22亿个Uppermons（3S）衰变样本中没有发现这种过程的证据，并将90%的C.L.相应分支级分的产物的上限。我们还对最近发现的eta_b介子的双μ子分支分数作了限制。
英文摘要：
We search for evidence of a light Higgs boson (A0) in the radiative decays of the narrow Upsilon(3S) resonance: Upsilon(3S) -> gamma A0, where A0 -> invisible or A0 -> mu+mu-. Such an object appears in extensions of the Standard Model, where a light CP-odd Higgs boson naturally couples strongly to b-quarks. We find no evidence for such processes in a sample of 122 million Upsilon(3S) decays collected by the BaBar collaboration at the PEP II B-factory, and set 90% C.L. upper limits on the product of the corresponding branching fractions. We also set a limit on the di-muon branching fraction of the recently discovered eta_b meson.
We report searches for a new muonic dark force mediated by a gauge boson ($Z'$) coupling only to the second and third lepton families. The existence of the $Z'$ boson is probed in $e^+e^- \to μ^+μ^- Z'$, $Z' \to μ^+ μ^-$ events, with an analysis based on the full data sample collected with the BABAR detector at the PEP-II $e^+e^-$ collider. No significant signal is observed. Limits on dark-sector coupling constants are derived; these improve upon current bounds, and further constrain the allowed parameter space.
Many models of physics beyond Standard Model predict the existence of light Higgs states, dark photons, and new gauge bosons mediating interactions between dark sectors and the Standard Model. Using a full data sample collected with the BABAR detector at the PEP-II $e^+e^-$ collider, we report searches for a light non-Standard Model Higgs boson, dark photon, and a new muonic dark force mediated by a gauge boson ($Z'$) coupling only to the second and third lepton families. Our results significantly improve upon the current bounds and further constrain the remaining region of the allowed paramet…
We present some recent measurements performed using 514 fb-1 of $e^+e^-$ collisions collected with the BaBar detector at the PEP-II asymmetric collider at SLAC. First we present a study of the decay tau -> K K_S nu, we measure the branching fraction B(tau -> K K_S nu), the mass spectrum of the K K_S system and obtain the spectral function. Our results are in agreement with and improve previous measurements. We then report a search for a dark boson A' produced in the reaction e+e- -> gamma A' in invisible final states A' -> chi anti-chi . We find no evidence for such processes and set 90% confi…
Many models of physics beyond the Standard Model predict the existence of new Abelian forces with new gauge bosons mediating interactions between "dark sectors" and the Standard Model. We report a search for a dark boson Z' coupling only to the second and third generations of leptons in the reaction e+e- -> mu+mu- Z', Z' -> mu+mu- using 514 fb-1 of data collected by the BABAR experiment. No significant signal is observed for Z' masses in the range 0.212 - 10 GeV. Limits on the coupling parameter g' as low as 7x10^-4 are derived, leading to improvements in the bounds compared to those previousl…
A search for the production of a single top quark in association with a Higgs boson is performed using the decay $\text{H} \to \text{b} \bar{\text{b}}$. The rate of this Higgs production mode is particularly sensitive to the relative sign of the Higgs boson couplings to fermions and bosons. The 2015 pp collisions data at a center-of-mass energy of 13 TeV are analyzed. This poster focuses on the discrimination between signal and background events. Upper limits, determined in the two-dimensional plane spanned by the coupling modifiers of the Higgs boson to top quarks and to vector bosons, are pr…
Searches for exotic decays of the 125 GeV Higgs boson performed with data collected by the CMS experiment are presented. Three classes of searches are detailed: searches for invisible decays of the Higgs boson, searches for lepton flavor violating Higgs decays, and searches for decays to the Higgs boson to light pseudoscalars decaying to SM particle pairs. These analyses are based on data collected at center-of-mass energies of 8 and 13 TeV.
A search for the standard model Higgs boson produced in association with a W or a Z boson and decaying a pair of $τ$ leptons is performed. A data sample of proton-proton collisions collected at $\sqrt{s} =$ 13 TeV by the CMS experiment at the CERN LHC is used, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. The signal strength is measured relative to the expectation for the standard model Higgs boson, yielding $μ=$ 2.5 $^{+1.4} _{-1.3}$. These results are combined with earlier CMS measurements targeting Higgs boson decays to a pair of $τ$ leptons, performed with the same data set …
Searches for Higgs Boson(s) at the Upgraded Tevatron
我们总结了希格斯玻色子玻色子搜索的状态在升级后的费米实验室Tevatron进行的DO和CDF合作。我们报告了三种类型的搜索，即1）标准模型希格斯玻色子的搜索（p \bar{p} --> H，WH或ZH，其中H --> WW* 和/或H --> b \bar{b}），2）使用p \bar{p} --> hb \bar{b}--> b \bar{b} b \bar{b}和p \bar{p} --> hX --> tau tau X来搜索最小超对称希格斯玻色子，3）寻找双电荷希格斯玻色子。
A search is performed for a pseudoscalar Higgs boson, A, decaying into a 125 GeV Higgs boson h and a Z boson. The h boson is specifically targeted in its decay into a pair of tau leptons, while the Z boson decays into a pair of electrons or muons. A data sample of proton-proton collisions collected by the CMS experiment at the LHC at $\sqrt{s} =$ 13 TeV is used, corresponding to an integrated luminosity of 35.9 fb$^{-1}$. No excess above the standard model background expectations is observed in data. A model-independent upper limit is set on the product of the gluon fusion production cross sec…
Measurements of the Higgs boson production and decay performed at the Large Hadron Collider by the ATLAS and CMS experiments are reviewed. These measurements are based on proton-proton collision data at $\sqrt{s}$=~13~TeV, corresponding to integrated luminosities ranging from 35 to 80~fb$^{-1}$. With these datasets, the associated production of the Higgs boson with a $t\bar{t}$ pair is observed and the decay of the Higgs boson to $b\bar{b}$ pairs is established. Measurements involving leptonic and bosonic final states are described. The combined constraints on the Higgs boson coupling properti…
Lepton flavor universality can be tested through the ratio of semileptonic $B$ meson decays and leptonic $Υ$ meson decays, with $Υ\equiv Υ(nS)$ ($n=1,2,3$). For the charged-current transitions $b \to cτ\barν_τ$, discrepancies between the experiment and the Standard Model (SM) have been observed in recent years by different flavor facilities such as BABAR, Belle, and LHCb. While for the neutral-current transitions $b \bar{b} \to τ\barτ$, the BABAR experiment reported recently a new measurement of leptonic decay ratio $R_{Υ(3S)} = {\rm BR}(Υ(3S) \to τ^+τ^-)/{\rm BR}(Υ(3S) \to μ^+μ^-)$, showing a…
The presence of charged Higgs bosons is a generic prediction of multiplet extensions of the Standard Model (SM) Higgs sector. Focusing on the Two-Higgs-Doublet-Model (2HDM), we discuss the charged Higgs boson collider phenomenology in the theoretically and experimentally viable parameter space. While almost all existing experimental searches at the LHC target the fermionic decays of charged Higgs bosons, we point out that the bosonic decay channels -- especially the decay into a non-SM-like Higgs boson and a $W$ boson -- often dominate over the fermionic channels. Moreover, we revisit two genu…
More than one Higgs boson may be present near the currently discovered Higgs mass, which can not be properly resolved due to the limitations in the intrinsic energy resolution at the Large Hadron Collider. We investigated the scenarios where two $CP$-even Higgs bosons are degenerate in mass. To correctly predict the Higgs signatures, quantum interference effects between the two Higgs bosons must be taken into account, which, however, has been often neglected in the literature. We carried out a global analysis including the interference effects for a variety of Higgs searching channels at the L…
Higgs Bosons produced via gluon-gluon fusion (ggF) with large transverse momentum ($p_T$) are sensitive probes of physics beyond the Standard Model. However, high $p_T$ Higgs Boson production is contaminated by a diversity of production modes other than ggF: vector boson fusion, production of a Higgs boson in association with a vector boson, and production of a Higgs boson with a top-quark pair. Combining jet substructure and event information with modern machine learning, we demonstrate the ability to focus on particular production modes. These tools hold great discovery potential for boosted…
In models with extended Higgs sector and additional matter fields, the decay modes of heavy Higgs bosons can be dominated by cascade decays through the new fermions rendering present search strategies ineffective. We investigate new decay topologies of heavy neutral Higgses in two Higgs doublet model with vectorlike leptons. We also discuss constraints from existing searches and discovery prospects. Among the most interesting signatures are monojet, mono Z, mono Higgs, and Z and Higgs bosons produced with a pair of charged leptons.
We interpret the potential observation of the 750 GeV di-photon resonance at the LHC in models, in which an $SU(2)$ isospin-singlet scalar boson mixes with the Standard Model (SM) Higgs boson through an angle $α$. Allowing the singlet scalar boson to have renormalizable couplings to vector-like leptons and quarks and introducing sizable decay width of the 750 GeV di-photon resonance into non-SM particles such as dark matters, we can explain the large production cross section $σ(H_2) \times B(H_2 \to γγ)$ as well as the apparent large total width of the boson without conflicts from the results …
Since the discovery of the Higgs boson in the year 2012, the CMS experiment continuously makes use of a variety of final states to measure the properties of the Higgs boson, as well as to search for it in final states where the discovery could not yet be established. This article concentrates on Higgs searches in fermionic final states including a search for the Standard Model Higgs boson in the $H \rightarrow b\overline{b}$ channel. Furthermore, three different searches for Higgs bosons beyond the Standard Model are presented. These comprise two searches for heavy neutral Higgs bosons and one…
在自然界的超对称理论中，希格斯玻色子的希格斯诺费米子超伴子可以作为最轻的标准模型超伴子出现，这取决于希格斯和超对称破缺扇区之间的耦合。在这封信中，希格斯诺对的生产和衰变的戈德斯通费米子的超对称性破缺和希格斯玻色子，h，或规范玻色子，Z或$γ$被认为是。相对干净的双玻色子终态，hh、$h γ$、hZ、$Z γ$或ZZ，具有大量丢失的能量结果。后者的渠道提供了新的发现模式的超对称性在高能对撞机，因为事件与Z玻色子通常被拒绝在超对称性搜索。此外，具有真实希格斯玻色子玻色子的最终态可能为在费米实验室Tevatron Run II上发现和研究希格斯信号提供有效的渠道。
