本研究全面分析$\u0001mathcal{Z}_{\ m N} \ imes \u0001mathcal{Z}_{\ m M}$味对称性味子的味现象学与多代对撞机探测潜力，明确不同质量、对称情形下的探测范围与约束。
摘要：
我们针对$\u0001mathcal{Z}_{\ m N} \ imes \u0001mathcal{Z}_{\ m M}$味对称性的味子（flavon）的味现象学与对撞机特征展开全面研究，涵盖软对称性破缺情形与一种新的对称性守恒机制，研究场景包括高亮度LHC、高能量LHC以及一台100 TeV强子对撞机。夸克与轻子可观测物的味物理对$\u0001mathcal{Z}_{\ m N} \ imes \u0001mathcal{Z}_{\ m M}$味对称性的味子参数空间施加了不同的约束。在对撞机层面，对于$\u0001mathcal{Z}_{\ m 8} \ imes \u0001mathcal{Z}_{\ m 22}$味对称性，衰变过程$t \ ightarrow c a$可被高亮度LHC、高能量LHC以及100 TeV强子对撞机探测。对于软对称性破缺情形下的重味子，在100 TeV对撞机上可利用遍举产生特征探测所有$\u0001mathcal{Z}_{\ m N} \ imes \u0001mathcal{Z}_{\ m M}$味对称性的味子。在软对称性破缺的低质量情形下，所有$\u0001mathcal{Z}_{\ m N} \ imes \u0001mathcal{Z}_{\ m M}$味对称性的味子都可在高能量LHC与100 TeV对撞机上被探测。双味子产生仅在轻味子情形下处于高亮度LHC、高能量LHC以及100 TeV对撞机的可达范围内。14 TeV高亮度LHC仅能通过少数特定的遍举特征探测$\u0001mathcal{Z}_{\ m 2} \ imes \u0001mathcal{Z}_{\ m 5}$与$\u0001mathcal{Z}_{\ m 8} \ imes \u0001mathcal{Z}_{\ m 22}$味对称性。对称性守恒情形仍超出任何对撞机的探测能力。
英文摘要：
We conduct a comprehensive investigation into the flavour phenomenology and collider signatures of flavon of $\mathcal{Z}_{\rm N} \times \mathcal{Z}_{\rm M}$ flavour symmetries for the soft symmetry-breaking scenario and a new symmetry-conserving mechanism at the high-luminosity LHC, high energy LHC, and a 100 TeV hadron collider. The flavour physics of quark and leptonic observables places different bounds on the parameter space of flavons of $\mathcal{Z}_{\rm N} \times \mathcal{Z}_{\rm M}$ flavour symmetries. On the collider side, the decay $t \rightarrow c a$ can be probed by the high-luminosity LHC, high energy LHC, and a 100 TeV hadron collider for the $\mathcal{Z}_{\rm 8} \times \mathcal{Z}_{\rm 22}$ flavour symmetry. The inclusive production signatures can be used to probe the flavon of all the $\mathcal{Z}_{\rm N} \times \mathcal{Z}_{\rm M} $ flavour symmetries for the soft symmetry-breaking scenario for a heavy flavon at a 100 TeV collider. Flavons of all the $\mathcal{Z}_{\rm N} \times \mathcal{Z}_{\rm M} $ flavour symmetries can be probed at high energy LHC and a 100 TeV collider for a low mass in the case of soft symmetry-breaking. The di-flavon production is within reach of the high-luminosity LHC, high energy LHC, and a 100 TeV collider only for a light flavon. The 14 TeV high-luminosity LHC can probe only the $\mathcal{Z}_{\rm 2} \times \mathcal{Z}_{\rm 5}$ and $\mathcal{Z}_{\rm 8} \times \mathcal{Z}_{\rm 22}$ flavour symmetries for a few specific inclusive signatures. The symmetry-conserving scenario remains beyond the detection capabilities of any collider.
Flavor symmetries are useful to realize fermion flavor structures in the standard model. In particular, discrete $A_4$ symmetry is used to realize lepton flavor structures, and some scalars which are called flavon are introduced to break this symmetry. In many models, flavons are assumed to be much heavier than the electroweak scale. However, our previous work showed that flavon mass around 100 GeV is allowed by experimental constraints in the $A_4$ symmetric model with residual $Z_3$ symmetry. In this paper, we discuss collider search of such a light flavon $φ_T$. We find that an electron - p…
The next generation of experiments in particle physics will for the first time systematically test flavor physics models based on flavon fields. Starting from the current quark-flavor constrains on such models we show how the new generation of lepton flavor experiments will dominate indirect searches in the coming decades. A future 100 TeV hadron collider will then be the first experiment to probe flavons as propagating degrees of freedom. Our estimate of the collider reach relies on a proper treatment of backgrounds and detector effects. Complementary searches for indirect effects in lepton f…
We present a study of the flavor changing decays $ϕ\to tc$ ($ϕ=H_F,\,A_F$) of the $CP$-even and $CP$-odd scalar flavons at the large hadron collider and its next stage, the high-luminosity large hadron collider. The theoretical framework is an extension of the standard model that incorporates an extra complex singlet and invokes the Froggatt-Nielsen mechanism with an Abelian flavor symmetry. The projected exclusion and discovery regions in terms of the model parameters are reported. We find that $A_F$ could be detected at the LHC by considering a reasonable scenario of the model parameter spac…
The search for Flavons with a mass of $\mathcal{O}$(1) TeV at current and future colliders might probe low-scale flavor models. We are interested in the simplest model that invokes the Froggatt-Nielsen (FN) mechanism with an Abelian flavor symmetry, which includes a Higgs doublet and a FN complex singlet. Assuming a CP conserving scalar potential, there are a $CP$-even $H_F$ and a $CP$-odd $A_F$ Flavons with lepton flavor violating (LFV) couplings. The former can mix with the standard-model-like Higgs boson, thereby inducing tree-level LFV Higgs interactions that may be at the reach of the LHC…
We consider a composite Higgs model based on the $SU(6)/Sp(6)$ coset, where an $U(1)$ subgroup of $Sp(6)$ is identified as the flavor symmetry. A complex scalar field $s$, which is a pseudo-Nambu-Goldstone boson of the broken symmetry, carries a flavor charge and plays the role of a flavon field. The $U(1)_F$ flavor symmetry is then broken by a VEV of the flavon field, which leads to a small parameter and generates the mass hierarchy between the top and bottom quarks. A light flavon below the TeV scale can be naturally introduced, which provides a fully testable model for the origin of flavor …
More often than not, models of flavor symmetry rely on the use of nonrenormalizable operators (in the guise of flavons) to accomplish the phenomenologically successful tribimaximal mixing of neutrinos. We show instead how a simple renormalizable two-parameter neutrino mass model of tribimaximal mixing can be constructed with the non-Abelian discrete symmetry T_7 and the gauging of B-L. This is also achieved without the addition of auxiliary symmetries and particles present in almost all other proposals. Most importantly, it is verifiable at the Large Hadron Collider.
We establish the possibility of having a pseudo-Nambu-Goldstone boson (pNGB) Dark Matter (DM) candidate in the inspired Froggatt-Nielsen Singlet Model (iFNSM) wherein a direct connection exists between the DM mass and new flavon symmetry-breaking scale. We find a considerable allowed region of parameter space for the ensuing pseudoscalar DM, which is dependent upon the flavon Vacuum Expectation Value (VEV) and Yukawa couplings, over which it may be possible to explain the fermion mass hierarchy. Finally, we choose a Benchmark Point (BP) and perform detailed collider analyses to probe this DM s…
In multiscale and topcolor-assisted models of walking technicolor, relatively light spin-one technihadrons $ρ_T$ and $ω_T$ exist and are expected to decay as $ρ_T \to W π_T, Z π_T$ and $ω_T \to γπ_T$. For $M_{ρ_T} \simeq 200 GeV$ and $M_{π_T} \simeq 100 GeV$, these processes have cross sections in the picobarn range in $\bar p p$ colisions at the Tevatron and about 10 times larger at the Large Hadron Collider. We demonstrate their detectability with simulations appropriate to Run II conditions at the Tevatron.
We discuss a general two-Higgs-doublet model with CP violation in the Higgs sector. In general, the three neutral Higgs fields of the model all mix and the resulting physical Higgs bosons have no definite CP properties. We derive a new sum rule relating Yukawa and Higgs-Z couplings which implies that a neutral Higgs boson cannot escape detection at an e^+e^- collider if it is kinematically accessible in Z+Higgs, $b\anti b+$Higgs and $t\anti t+$Higgs production, irrespective of the mixing angles and the masses of the other neutral Higgs bosons. We also discuss modifications of the sum rules and…
The long-standing muon g-2 anomaly can be explained by heavy new physics particles through chirally enhanced contributions. It has been recently proposed that a muon collider running at center-of-mass energies of several TeV could test these new physics scenarios in a model-independent way, through the study of high-energy processes such as mu+ mu- --> h gamma. In this work, we validate these findings, based on effective field theories, by considering selected renormalizable simplified models and by computing this one-loop process in full generality. Furthermore, we explore the interplay of di…
A signal of two leptons and missing energy is challenging to analyze at the Large Hadron Collider (LHC) since it offers only few kinematical handles. This signature generally arises from pair production of heavy charged particles which each decay into a lepton and a weakly interacting stable particle. Here this class of processes is analyzed with minimal model assumptions by considering all possible combinations of spin 0, 1/2 or 1, and of weak iso-singlets, -doublets or -triplets for the new particles. Adding to existing work on mass and spin measurements, two new variables for spin determina…
Direct detection of and LHC search for the singlet fermion dark matter (SFDM) model with Higgs portal interaction are considered in a renormalizable model where the full Standard Model (SM) gauge symmetry is imposed by introducing a singlet scalar messenger. In this model, direct detection is described by an effective operator m_q \bar{q} q \barχ χas usual, but the full amplitude for monojet + \not E_T involves two intermediate scalar propagators, which cannot be seen within the effective field theory (EFT) or in the simplified model without the full SM gauge symmetry. We derive the collider b…
In the context of high-energy physics, a reliable description of the parton-level kinematics plays a crucial role for understanding the internal structure of hadrons and improving the precision of the calculations. Here, we study the production of one hadron and a direct photon, including up to Next-to-Leading Order Quantum Chromodynamics and Leading-Order Quantum Electrodynamics corrections. Using a code based on Monte-Carlo integration, we simulate the collisions and analyze the events to determine the correlations among measurable and partonic quantities. Then, we use these results to feed …
In this paper we propose a new strategy, based on anomaly detection methods, to search for new physics phenomena at colliders independently of the details of such new events. For this purpose, machine learning techniques are trained using Standard Model events, with the corresponding outputs being sensitive to physics beyond it. We explore three novel AD methods in HEP: Isolation Forest, Histogram Based Outlier Detection, and Deep Support Vector Data Description; alongside the most customary Autoencoder. In order to evaluate the sensitivity of the proposed approach, predictions from specific n…
In this work, we derive lower mass bounds on the Z' gauge boson based on the dilepton data from LHC with 13 TeV of center-of-mass energy, and forecast the sensitivity of the High-Luminosity-LHC with $L=3000 fb^{-1}$, the High-Energy LHC with $\sqrt{s}=27$ TeV, and also at the Future Circular Collider with $\sqrt{s}=100$ TeV. We take into account the presence of exotic and invisible decays of the Z' gauge boson to find a more conservative and robust limit, different from previous studies. We investigate the impact of these new decays channels for several benchmark models in the scope of two dif…
We study a realistic top-down M-theory compactification with low-scale effective Supersymmetry, consistent with phenomenological constraints. A combination of top-down and generic phenomenological constraints fix the spectrum. The gluino mass is predicted to be about 1.5 TeV. Three and only three superpartner channels, $\tilde{g} \tilde{g}$, $χ_2^0 χ_1^\pm$ and $χ_1^+ χ_1^-$ (where $χ_2^0, χ_1^\pm$ are Wino-like), are expected to be observable at LHC-14. We also investigate the prospects of finding heavy squarks and Higgsinos at future colliders. Gluino-stop-top, gluino-sbottom-bottom associat…
We survey techniques for finding a CP-odd Higgs boson, A, at the Linear Collider that do not depend upon the presence of other light Higgs bosons. The potential reach in $[m_A,\tanβ]$ parameter space for various production/discovery modes is evaluated and regions where discovery might not be possible at a given $\sqrt{s}$ are delineated. We give, for the first time, results for $\epem\to ν\antiνA$ one-loop $W$ boson fusion production.
We show that a class of parity based solutions to the strong CP problem predicts new colored particles with mass at the TeV scale, due to constraints from Planck suppressed operators. The new particles are copies of the Standard Model quarks and leptons. The new quarks can be produced at the LHC and are either collider stable or decay into Standard Model quarks through a Higgs, a W or a Z boson. We discuss some simple but generic predictions of the models for the LHC and find signatures not related to the traditional solutions of the hierarchy problem. We thus provide alternative motivation fo…
With increasing energy and luminosity available at the Large Hadron collider (LHC), we get a chance to take a pure bottom-up approach solely based on data. This will extend the scope of our understanding about Nature without relying on theoretical prejudices. The required computing resource, however, will increase exponentially with data size and complexities of events if one uses algorithms based on a classical computer. In this letter we propose a simple and well motivated method with a quantum annealer to identify an event-topology, a diagram to describe the history of particles produced at…
We investigate the effect of QCD resummation to kinematical correlations in the Higgs boson plus high transverse momentum (Pt) jet events produced at hadron colliders. We show that at the complete one-loop order, the Collins-Soper-Sterman resummation formalism can be applied to derive the Sudakov form factor, which is found to be independent of jet-finding algorithm. We compare the singular behavior of resummation calculation to fixed order prediction in the case that Higgs boson and high Pt jet are produced nearly back-to-back in their transverse momenta, and find a perfect agreement. The phe…
High-multiplicity proton-proton (pp) collisions at the Large Hadron Collider (LHC) energies have created a new domain of research to look for a possible formation of quark-gluon plasma in these events. In this paper, we estimate various thermal properties of the matter formed in pp collisions at the LHC energies, such as mean free path, isobaric expansivity, thermal pressure, and heat capacity using a thermodynamically consistent Tsallis distribution function. Particle species-dependent mean free path and isobaric expansivity are studied as functions of final state charged particle multiplicit…
High-energy data has been accumulating over the last ten years, and it should not be ignored when making decisions about the future experimental program. In particular, we argue that the electroweak data collected at LEP, SLC and Tevatron indicate a light scalar particle with mass less than 500 GeV. This result is based on considering a wide variety of theories including the Standard Model, supersymmetry, large extra dimensions, and composite models. We argue that a high luminosity, 600 GeV e+e- collider would then be the natural choice to feel confident about finding and studying states conne…
As the 125 GeV Higgs becomes disfavored as a portal to the dark sector, one is motivated to look beyond the SM-Higgs sector, into extended scalar-mediated portal mechanisms. In this work we consider one interesting possibility of such extended scalar sector, namely Type X two Higgs doublet with a scalar singlet dark matter. This model with the advantage of light pseudoscalars also provides the explanation for the observed anomalous magnetic moment of muon. The dark matter phenomenology of this model is unique from the other types of two Higgs doublet models. Therefore, it is quite intriguing t…
We analyze the potential of the Fermilab Tevatron and CERN Large Hadron Collider (LHC) to study anomalous quartic vector--boson interactions (photon photon Z Z) and (photon photon W+ W-). Working in the framework of SU(2)_L X U(1)_Y chiral Lagrangians, we study the production of photons pairs accompanied by (e+e-), (e nu), and jet pairs to impose bounds on these new couplings, taking into account the unitarity constraints. We compare our findings with the indirect limits coming from precision electroweak measurements as well as with presently available direct searches at LEPII. We show that th…
ATLAS and CMS have discovered a Standard Model Higgs-like particle. One of the main discovery channels is the Higgs decay to two photons, which, at the moment, seems to be considerably enhanced over the Standard Model expectation. Models with additional charged matter coupling to the Higgs sector can enhance or decrease the Higgs to two photons branching ratio. We take this as motivation to confront the so-called Georgi-Machacek model of Higgs triplets with the results of recent searches for a SM Higgs boson performed at the LHC. We also investigate the model in regions of the allowed paramete…
The current 7 TeV run of the LHC experiment shall be able to probe gluino and squark masses up to values larger than 1 TeV. Assuming that hints for SUSY are found in the jets plus missing energy channel by the end of a 5 fb$^{-1}$ run, we explore the flavour constraints on three models with a CMSSM-like spectrum: the CMSSM itself, a Seesaw extension of the CMSSM, and Flavoured CMSSM. In particular, we focus on decays that might have been measured by the time the run is concluded, such as $B_s\toμμ$ and $μ\to eγ$. We also analyse constraints imposed by neutral meson bounds and electric dipole m…
The quest for the Higgs boson of the Standard Model, which was a cornerstone in the physics programme at particle colliders operating at the energy frontier for several decades, is the subject of this review. After reviewing the formulation of electroweak symmetry breaking via the Higgs mechanism within the Standard Model, the phenomenology of the Higgs boson at colliders and the theoretical and phenomenological constraints on the Standard Model Higgs sector are discussed. General remarks on experimental searches and the methodology of statistical interpretation are followed by a description o…
We study the diffusion of charm and beauty in the early stage of high energy nuclear collisions at RHIC and LHC energies, considering the interaction of these heavy quarks with the evolving Glasma by means of the Wong equations. In comparison with previous works, we add the longitudinal expansion as well as we estimate the effect of energy loss due to gluon radiation. We find that heavy quarks diffuse in the strong transverse color fields in the very early stage (0.2-0.3 fm/c) and this leads to a suppression at low $p_T$ and enhancement at intermediate low $p_T$. The shape of the observed nucl…
Operator Identification in Charged Lepton-Flavor Violation: Global EFT Analysis with RG Evolution, Polarization Observables, and Bayesian Model Discrimination at Future Colliders
Universidad Técnica Federico Santa María（弗雷德里克·萨马利亚技术大学）；Millennium Institute for Subatomic Physics at the High-Energy Frontier (SAPHIR)（高能前沿亚原子物理千年研究所（SAPHIR））
We revisit the potential of a Linear Collider concerning the study of lepton flavour violation, in view of new LHC bounds and of the (very) recent developments in lepton physics. Working in the framework of a type I supersymmetric seesaw, we evaluate the prospects of observing seesaw-induced lepton flavour violating final states of the type e μ+ missing energy, arising from e+ e- and e- e- collisions. In both cases we address the potential background from standard model and supersymmetric charged currents. We also explore the possibility of electron and positron beam polarisation. The statisti…
In this work we study the interactions of the $Z$ and $Z^{\prime}$ generated by kinetic mixing in a class of theories for physics beyond the standard model motivated by the dark matter problem, containing a spontaneously broken extra $U(1)_{d}$ gauge factor group in a hidden scenario and a Higgs sector respecting custodial symmetry. It is shown that custodial symmetry allows us to write the $Z$ and $Z^{\prime}$ couplings to standard model fermions in terms of the measured values of $α$, $G_{F}$, $M_{Z}$ and $M_{Z^{\prime}}$. Working at the loop level, we calculate the ratio $ρ_{0}=M^{2}_{W}/\h…
The existence of mirror partners of Standard-Model fermions offers a viable alternative to a fundamental BEH mechanism, with the coupling corresponding to the gauged mirror generation symmetry becoming naturally strong at energies around 1 TeV. The resulting non-perturbative processes produce dynamical katoptron masses which might range from 0.1 to 1.15 TeV in a way circumventing usual problems with the S parameter. Moreover, they create mirror mesons belonging in two main groups, with masses differing from each other approximately by a factor of six and which might range approximately from 0.…
We present preliminary results of the first convergent global fits of several minimal composite Higgs models. Our fits are performed using the differential evolution optimisation package $\texttt{Diver}$. A variety of physical constraints are taken into account, including a wide range of exclusion bounds on heavy resonance production from Run 2 of the LHC. As a by-product of the fits, we analyse the collider phenomenology of the lightest new up-type and down-type resonances in the viable regions of our models, finding some low-mass resonances that can be probed in future collider searches.
The high-multiplicity pp collisions at the Large Hadron Collider energies with various heavy-ion-like signatures have warranted a deeper understanding of the underlying physics and particle production mechanisms. It is a common practice to use experimental data on the hadronic transverse momentum ($p_T$) spectra to extract thermodynamical properties of the system formed in heavy ion and high multiplicity pp collisions. The non-availability of event topology dependent experimental data for pp collisions at $\sqrt{s}$ = 13 TeV on the spectra of non-strange and strange hadrons constrains us to us…
To have a better understanding of the matter formed in ultra-relativistic collisions, using the Color String Percolation Model (CSPM), we have estimated initial energy density, mean free path, squared speed of sound, shear viscosity to entropy density ratio ($η/s$), bulk viscosity to entropy density ratio and bulk modulus for $pp$, $p$-Pb, Xe-Xe and Pb-Pb collisions at the Large Hadron Collider (LHC). These observables are studied as a function of final state charged particle multiplicity density and initial state percolation temperature. The results from this work are compared with the result…
A pressing problem for supersymmetry (SUSY) phenomenologists is how to incorporate Large Hadron Collider search results into parameter fits designed to measure or constrain the SUSY parameters. Owing to the computational expense of fully simulating lots of points in a generic SUSY space to aid the calculation of the likelihoods, the limits published by experimental collaborations are frequently interpreted in slices of reduced parameter spaces. For example, both ATLAS and CMS have presented results in the Constrained Minimal Supersymmetric Model (CMSSM) by fixing two of four parameters, and ge…
