分类: 物理学 >> 基本粒子与场物理学 提交时间: 2020-11-02
摘要: In this note, we investigate the anomalies in field theories. The results of the anomalies through Feynman diagrams calculation are multi-valued function. These single-valued branches of multi-valued function are related to the bound states of neutral pseudoscalar mesons. Adding these bound state contributions, we obtain a new anomaly free condition that all the external particles are on-shell and find the non-perturbative mass spectrum of neutral pseudoscalar mesons. We also discuss the anomaly in 2 dimensional QFT.
分类: 物理学 >> 普通物理:统计和量子力学,量子信息等 提交时间: 2023-02-17
摘要: The paper proposes a statistical fields theory of quantum reference frame underlying the Perelman's analogies between his formalism of the Ricci flow and the thermodynamics. The theory is based on a $d=4-\epsilon$ quantum non-linear sigma model (NLSM), interpreted as a quantum reference frame system which a to-be-studied quantum system is relative to.The statistic physics and thermodynamics of the quantum frame fields is studied by the density matrix of them obtained by the Gaussian approximation quantization. The induced Ricci flow of the frame fields and the Ricci-DeTurck flow of the frame fields associated with the density matrix is deduced. In this framework, the diffeomorphism anomaly of the theory has deep thermodynamic interpretation. The trace anomaly is related to a Shannon entropy in terms of the density matrix, which monotonically flows and achieves its maximal value at the flow limit,called the Gradient Shrinking Ricci Soliton (GSRS). A relative Shannon entropy w.r.t. the maximal entropy gives a statistical interpretation to Perelman's partition function, which is also monotonic and giving an analogous H-theorem to the statistical frame fields system. We find that a temporal static 3-space of the GSRS spacetime is in a thermal equilibrium state, and Perelman's analogies between his formalism and the thermodynamics of the frame fields in equilibrium can be explicitly given in the framework. As a possible underlying microscopic theory of the gravitational system, the theory is also applied to understand the thermodynamics of the Schwarzschild black hole. The cosmological constant in the effective theory of gravity at cosmic scale is also briefly given.
分类: 物理学 >> 核物理学 提交时间: 2016-09-10
摘要: We extract the e+e−→π+π− cross section in the energy range between 600 and 900 MeV, exploiting the method of initial state radiation. A data set with an integrated luminosity of 2.93 fb−1 taken at a center-of-mass energy of 3.773 GeV with the BESIII detector at the BEPCII collider is used. The cross section is measured with a systematic uncertainty of 0.9%. We extract the pion form factor |Fπ|2 as well as the contribution of the measured cross section to the leading order hadronic vacuum polarization contribution to (g−2)μ. We find this value to be aππ,LOμ(600−900MeV)=(368.2±2.5stat±3.3sys)⋅10−10.
分类: 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: We propose to interpret the 750 GeV diphoton excess in deflected anomaly mediation supersymmetry breaking scenarios, which can naturally predict couplings be- tween a singlet field and vector-like messengers. The CP-even scalar component (S) of the singlet field can serve as the 750 GeV resonance. The messenger scale, which is of order the gravitino scale, can be as light as Fφ ∼ O(10) TeV when the messenger species NF and the deflection parameter d are moderately large. Such messengers can induce the large loop decay process S → γγ. Our results show that such a scenario can successfully accommo- date the 125 GeV Higgs boson, the 750 GeV diphoton excess and the muon g − 2 without conflicting with the LHC constraints. We also comment on the possible explanations in the gauge mediation supersymmetry breaking scenario.
分类: 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: In order to explain the Tevatron anomaly of the top quark forward-backward asymmetry AtFBAFBtA_{FB}^t in the left-right twin Higgs model, we choose to give up the lightest neutral particle of h^h^\hat{h} field as a stable dark matter candidate. Then a new
分类: 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: We propose a deflected anomaly mediation scenario from SUSY QCD which can lead to both positive and negative deflection parameters (there is a smooth transition between these two deflection parameter regions by adjusting certain couplings). Such a scenario can naturally give a SUSY spectrum in which all the colored sparticles are heavy while the sleptons are light. As a result, the discrepancy between the Brookheaven gμ − 2 experiment and LHC data can be reconciled in this scenario. We also find that the parameter space for explaining the gμ − 2 anomaly at 1σ level can be fully covered by the future LUX-ZEPLIN 7.2 Ton experiment.
分类: 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-27
摘要: A radiative natural SUSY spectrum are proposed in the deflected anomaly mediation scenario with general messenger-matter interactions. Due to the contributions from the new interactions, positive slepton masses as well as a large |Att_{t} | term can natur
分类: 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: From generalized gravity mediation we build a SUGRA scenario in which the gluino is much heavier than the electroweak gauginos at the GUT scale. We find that such a non-universal gaugino scenario with very heavy gluino at the GUT scale can be naturally ob
分类: 分类: 物理学 >> 基本粒子与场物理学 提交时间: 2016-12-28
摘要: The Zbb coupling determined from the Z-pole measurements at LEP/SLD shows an about 3-sigma deviation from the SM prediction, which would signal the presence of new physics in association with the Zbb coupling. In this work we give a comprehensive study fo