In this paper, we study radiative decays of X_b, the counterpart of the famous X(3872) in the bottomonium-sector as a candidate for meson-meson molecule, into the γΥ(nS) (n=1, 2, 3). Since it is likely that the X_b is below the B\bar B^* threshold and the mass difference between the neutral and charged bottom meson is small compared to the binding energy of the X_b, the isospin violating decay mode X_b\to Υ(nS)π^+π^- would be greatly suppressed. This will promote the importance of the radiative decays. We use the effective Lagrangian based on the heavy quark symmetry to explore the rescattering mechanism and calculate the partial widths. Our results show that the partial widths into γΥ(nS) are about 1 keV, and thus the branching fractions may be sizeable, considering the fact the total width may also be smaller than a few MeV like the X(3872). These radiative decay modes are of great importance in the experimental search for the X_b particularly at hadron collider. An observation of the X_b will provide a deeper insight into the exotic hadron spectroscopy and is helpful to unravel the nature of the states connected by the heavy quark symmetry.
We propose a new experiment to search for a time-reversal (T) symmetry breaking process in muon decay and the Majoranality of the neutrinos. In the presence of V+A interactions, the Majoranality appears as a T-violating term in the muon decay width as shown by Doi et al, while in the Standard Model such a T-violating term is negligibly small. The presences of V+A interactions and the corresponding heavy right-handed Majorana neutrinos give us an important clue to solve two major issues in particle physics, the deficit of baryon asymmetry in the universe and the Majoranality of neutrinos. In th…
Hunting physics beyond the standard model with unusual $W^\pm$ and $Z$ decays
在扩展的超对称模型的框架内，$W^\pm$和$Z$玻色子的非标准壳层衰变是可能的，即，与最小超对称标准模型相比，具有单重态和/或新的耦合。这些模式通常出现在参数空间中具有轻单态标量、伪标量和中性伴子的区域。在这封信中，我们强调这些状态如何导致新的信号在对撞机从$Z$ -或$W^\pm$ -玻色子衰变与提示或位移的多轻子/τ喷流/喷流/光子在最终状态。这些新的模式将提供新物理学的明显证据，即使直接搜索仍然不成功。我们讨论了探测这些新的信号使用现有的大型强子对撞机运行I数据集的可能性。我们也解决了同样的情况下，大型强子对撞机运行-II，以及为未来的对撞机。我们用“$μ$ from $ν$“超对称标准模型来解释我们的观测，其中三代右手中微子超场被用来解决最小超对称标准模型的缺点。我们还扩展了我们的讨论的其他变种的超对称模型，可以容纳类似的签名。
In the present work, we investigate the productions of the molecular states composed of $D^{(*)}_s \bar{D}^{(*)}$ and $D^{(*)}_s \bar{D}^{(*)}_s$ in the $B$ and $B_s$ decays by using an effective Lagrangian approach. The branching ratios in terms of the model parameter $α$ and the binding energy $ΔE$ are estimated. Our estimations indicate that the branching fractions are of the order of $10^{-4}$ and the relative ratios are very weakly dependent on the model parameter $α$ and the binding energy $ΔE$. The predicted ratios are helpful for searching the hidden-charm molecular states with strange…
The assumption that strongly interacting sparticles will decay directly to the LSP plus jets breaks down in situations where those decays are Yukawa suppressed. That occurs when producing the first two generations of squarks and when, at the same time, there are several electroweakinos lighter than those squarks. In this paper we analyze the signal of pair production of squarks that subsequently decay to an intermediate neutralino ($\tildeχ_3^0$) plus jets. The neutralino will then decay to the LSP (mainly higgsino) and a Higgs. We have simulated the events and designed a discovery strategy ba…
在最小超对称标准模型中，当参数tan β很大时，B物理对希格斯玻色子的影响很敏感。我简要地总结了B -> mu+ mu-和B -> tau nu在寻找新的希格斯效应中的作用，并提出了关于衰变B -> D tau nu的新结果：利用形状因子的解析性质，人们可以预测比率R=Br（B-> D tau nu）/Br（B -> D l nu），l=e，mu，具有小的强子不确定性。在标准模型中，如果使用重风味平均组的矢量形状因子，则发现R= 0.31 +/- 0.02，Br（B^- -> D^0 tau^-抗-nu）=（0.71 +/- 0.09）%和Br（抗-B ^0 -> D^+ tau^-抗-nu）=（0.66 +/- 0.08）%。B -> D τ nu与B -> τ nu在寻找带电希格斯玻色子玻色子效应方面具有竞争力。对后者特别敏感的是衰变链anti-B -> D anti-nu tau^-[-> pi-nu]中的微分分布。
We show the reinterpretation of existing searches for exotic decays of the Standard Model (SM)-like Higgs, $H \to aa (hh)$, in various final states, in the framework of the 2-Higgs Doublet Model (2HDM) Type-I. We then explore a new search for such light Higgses, $a$ and $h$, at the Large Hadron Collider (LHC) Run 3 for an integrated luminosity of 300 $\text{fb}^{-1}$. After performing a scan over the model parameters, we found that the inverted scenario of Type-I offers a new promising signal in the form of the following cascade decays: $H \to Z^{*}a \to Z^{*}Z^{*}h \to b\overline{b} μ^- μ^+ j…
In perturbative QCD approach, based on the first order of isospin symmetry breaking, we study the direct $CP$ violation in the decay of $\bar{B}_s^0\toρ(ω)K^{*0}\to {π^+}{π^-}K^{*0}$. An interesting mechanism is applied to enlarge the $CP$ violating asymmetry involving the charge symmetry breaking between $ρ$ and $ω$. We find that the $CP$ violation is large by the $ρ-ω$ mixing mechanism when the invariant masses of the $π^+π^-$ pairs is in the vicinity of the $ω$ resonance. For the decay process of $\bar{B}^0_{s}\toρ(ω)K^{*0}\to{π^+}{π^-}K^{*0}$, the maximum $CP$ violation can reach $-59.12\%…
Vector-like top partner plays a central role in many new physics models which attempt to address the hierarchy problem. The top partner is conventionally assumed to decay to a quark and a SM boson. However, it is also possible that the top partner decays to a non-SM scalar and a top quark. Such an exotic decay channel can be the main decay channel of top partner, and thus provides new windows to search for top partner at the LHC. In this paper, with classical machine learning method Boosted Decision Tree (BDT), we perform a model independent study of the discovery potential of this new signatu…
We study the photon spectrum in the radiative decays of the charmonium $\frac{1}Γ\frac{dΓ(J/ψ\rightarrowγgg)}{dz}$ as an excellent scene for hunting the exotic mesons (hybrids $q\bar{q}g$ and glueballs $gg$) and an ideal frame for the theoretical and phenomenological investigations of the gluon nature in IR, by subtle estimation of its non-zero effective mass which seems required in Quark-Gluon Constituent Model (QGCM) for identifying the nature of these exotic species.
In 15 years of data taking the Pierre Auger Observatory has observed no events beyond $10^{11.3}$ GeV. This null result translates into an upper bound on the flux of ultrahigh-energy cosmic rays implying $J (> 10^{11.3}$ GeV) $< 3.6 \times 10^{-5}$ km$^{-2}$ sr$^{-1}$ yr$^{-1}$, at the 90\%C.L. We interpret this bound as a constraint on extreme-energy photons originating in the decay super-heavy dark matter (SHDM) particles clustered in the Galactic halo. Armed with this constraint we derive the strongest lower limit on the lifetime of hadronically decaying SHDM particles with masses in the ra…
We analyze decays of vectorlike quarks in extensions of the standard model and a two Higgs doublet model. We identify several typical patterns of branching ratios of the lightest new up-type quark, $t_4$, and down-type quark, $b_4$, depending on the structure of Yukawa couplings that mix the vectorlike and standard model quarks (we assume only mixing with the third generation) and also on their doublet or singlet nature. We find that decays into heavy neutral or charged Higgs bosons, when kinematically open, can easily dominate and even be close to 100\%: $b_4\to H b$ at medium to large $\tan …
A recent preliminary investigation based on Durgut's report at the American Physical Society site shows a structure at $18.4~ {\rm GeV}$ exists in the invariant mass distribution of $Υl^+l^- ~ (l = e,\, μ)$ at the LHC center-of-mass energy of $7$ and $8~ {\rm TeV}$. Its appearance attracts attention of theorists and experimentalists of high energy physics, because it might be a Higgs-like boson of $18.4~ {\rm GeV}$ which would serve as a signal of the new physics beyond the Standard Model. We have carried out computations on the corresponding quantities (production and decay rates) based on qu…
Hunting for new physics in $B$ meson $b \to u$ transitions: A fresh look with Belle II data
Istituto Nazionale di Fisica Nucleare, Sezione di Bari（意大利国家核物理研究所巴里分部）；Dipartimento Interateneo di Fisica ”Michelangelo Merlin”, Università degli Studi di Bari（巴里大学米开朗基罗·梅林联合物理系）
We perform a comprehensive global analysis in the Minimal Supersymmetric Standard Model (MSSM) as well as in the 2-Higgs Doublet Model (2HDM) of the production and decay mechanisms of charged Higgs bosons $(H^\pm)$ at the Large Hadron Collider (LHC). Starting from the most recent experimental results (SM-like Higgs boson signal strengths and search limits for new Higgs boson states obtained at Run-1 and -2 of the LHC and previous colliders), from (both direct and indirect) searches for Supersymmetric particles as well as from flavor observables (from both $e^+e^-$ factories and hadron collider…
At any epoch, particle physics must be open to completely unexpected discoveries, and that is reason enough to extend the reach of searches for ultra-high energy (UHE) photons. The observation of a population of photons with energies $E \gtrsim 100$ EeV would for example imply the existence of either a completely new physical phenomena, or particle acceleration mechanisms heretofore never seen or imagined. But as we outline in this Letter of Interest, there are also good arguments for super-heavy dark matter (SHDM) in a parameter range such that it could be discovered via its decays to, in par…
