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High Energy Physics - Phenomenology (hep-ph)

Fri, 21 Apr 2023

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1.Hunting scalar partners of the Higgs boson at the LHC

Authors:Werner Porod

Abstract: Composite Higgs models with a fermionic ultraviolet completion predict in general additional pseudo Nambu Goldstone bosons beside the Higgs multiplet. In this contribution we discuss their LHC signatures and present first bounds in simplified models which can also be applied to generic models like multi-Higgs models. We then demonstrate how these can be combined taking a concrete model based on the SU(5)/SO(5) coset as an example. We use this to show how a proper combination of different channels can lead to an improved bound compared to a single channel analysis.

2.eHIJING: an Event Generator for Jet Tomography in Electron-Ion Collisions

Authors:Weiyao Ke, Yuan-Yuan Zhang, Hongxi Xing, Xin-Nian Wang

Abstract: We develop the first event generator, the electron-Heavy-Ion-Jet-Interaction-Generator (eHIJING), for the jet tomography study of electron-ion collisions. In this generator, energetic jet partons produced from the initial hard scattering undergo multiple collisions with the nuclear remnants with a collision rate that is proportional to the transverse-momentum-dependent (TMD) gluon densities in the nucleus. Medium-modified QCD parton splittings within the higher-twist and generalized higher-twist framework are utilized to simulate parton showering in the nuclear medium that takes into account the non-Abelian Landau-Pomeranchuck-Midgal interference in gluon radiation induced by multiple scatterings. The TMD gluon distribution inside the nucleus is given by a simple model inspired by the physics of gluon saturation. Employing eHIJING, we revisit hadron production in semi-inclusive deep inelastic scattering (SIDIS) as measured by EMC, HERMES as well as recent CLAS experiments. eHIJING with both the higher-twist and generalized higher-twist framework gives reasonably good descriptions of these experimental data. Predictions for experiments at the future electron-ion colliders are also provided. It is demonstrated that future measurements of the transverse momentum broadening of single hadron spectra can be used to map out the two dimensional kinematic ($Q^2, x_B$) dependence the jet transport parameter $\hat{q}$ in cold nuclear matter.

3.Running anomalous dimensions in holographic QCD: from the proton to the sexaquark

Authors:Nick Evans, Matthew Ward

Abstract: In holographic models of QCD, the running of the anomalous dimension of the quark bilinear operator leads to chiral symmetry breaking when gamma=1 and the Breitenlohner-Freedman bound is violated. In that case, the running drives the sigma meson mass tachyonic inducing the chiral symmetry breaking. Here we include the running anomalous dimension in the computation of the spectrum of bound states associated with other operators made of light quarks, such as the nucleon and exotic sexaquark states. We show that including the one loop gauge theory running can have substantial effects on the predictions. For example, the nucleon mass to rho mass ratio is improved and lies much closer to the observed value. A similar result is obtained for the Lambda and Xi baryons when strange quarks are included. A uuddss sexaquark state with a low enough mass to make it stable can be achieved, but this depends on the input assumptions about the running dimension.

4.Effects of clustered nuclear geometry on the anisotropic flow in O--O collisions at the LHC within a multiphase transport model framework

Authors:Debadatta Behera, Suraj Prasad, Neelkamal Mallick, Raghunath Sahoo

Abstract: To understand the true origin of flow-like signatures and applicability of hydrodynamics in small collision systems, effects of soft QCD dynamics, the sensitivity of jet-like correlations, and non-equilibrium effects, efforts are being made to perform \textit{p}--O and O--O collisions at the LHC and RHIC energies. It is equally interesting to look into the possible signatures of an $\alpha$--clustered nuclear geometry in $^{16}$O--$^{16}$O collisions by studying the initial-state effects on the final-state observables. In this work, within a multiphase transport model, we implement an $\alpha$--cluster tetrahedral density profile in the Oxygen nucleus along with the default Woods-Saxon density profile. We study the eccentricity ($\epsilon_2$), triangularity ($\epsilon_3$), normalized symmetric cumulants (NCS(2,3)), elliptic flow ($v_2$), and triangular flow ($v_3$) in $^{16}$O--$^{16}$O collisions at $\sqrt{s_{\rm NN}} = 7~$TeV. The constituent quark number scaling of the elliptic flow is also reported. For the most central collisions, enhanced effects in $\langle \epsilon_3 \rangle/ \langle \epsilon_2 \rangle$ and $\langle v_3 \rangle/ \langle v_2 \rangle$ with a negative value of NSC(2,3), and an away-side broadening in the two-particle azimuthal correlation function ($C(\Delta \phi)$) of the identified particles are observed in the presence of an $\alpha$--clustered geometry.

5.Analysis and study of the hidden-charm pentaquark states based on magnetic moment and transition magnetic moment

Authors:Fei Guo, Hao-Song Li

Abstract: In this work, we calculate magnetic moments and transition magnetic moments of the $P^{N^{0}}_{\psi}$ states in molecular model, diquark-diquark-antiquark model and diquark-triquark model, whose isospin doublet state $P^{N^{+}}_{\psi}$ has been observed in the LHCb Collaboration in recent years. Our results show that in the diquark-diquark-antiquark model, the magnetic moments of $\lambda $ excitation state are usually larger than the magnetic moments of $\rho $ excitation state. We find some interesting proportional relationships between the expressions of transition magnetic moments. The results provide important insights for future experimental observation of $P^{N^{0}}_{\psi}$ states and help to distinguish their inner structures. With these efforts, our understanding of the properties for the hidden-charm pentaquark states will become more abundant.

6.Multi-skyrmion states in the Skyrme model with false vaccum potential

Authors:Jun-Shuai Wang, Yong-Liang Ma

Abstract: We study the multi-skyrmion states using a Skyrme model with false vacuum potential upto baryon number $B=8$ using the product ansatz. It is found that, both the false vacuum potential and true vacuum potential can yield cluster structure of the multi-skyrmion states. The effect of the explicit chiral breaking on the masses and the contour surfaces of the baryon number density of the multi-skyrmion states are analyzed.

7.Dilaton photoproduction in a magnetic dipole field of pulsars and magnetars

Authors:Mikhail Astashenkov

Abstract: According to Einstein-Maxwell-Dilaton theory, the dilaton field $\psi$ can be produced by electromagnetic fields with non-zero Maxwell invariant. So electromagnetic wave propagating in an external electromagnetic field is a typical source of dilaton radiation. For study dilaton photoproduction in astrophysical conditions it's interesting to consider plane elliptically polarized electromagnetic wave propagating in the electromagnetic field of magnetic dipole ${\bf m}$ of pulsars and magnetars. The dilation field equation is solved in case $|\psi| \ll 1$. The angular distribution dilaton radiation is studied in every point of space. It's shown that spectral composition of dilatons is similar to spectral composition of plane electromagnetic wave. Amount of dilaton energy radiated in time and all directions is greatest in condition $(B_1^2-B_2^2)(m_x^2-m_y^2)\geq 0,$ where $B_1$ and $B_2$ are electromagnetic wave amplitudes along the axes of polarization ellipse. This condition is valid for many neutron star systems.

8.CP asymmetry from resonance effect of B meson decay process with $π$ and K final states

Authors:Gang Lü, Xi-Liang Yuan, Na-Wang, Xin-Heng Guo

Abstract: We introduce the new resonance of $V\rightarrow K^{+}K^{-}$ $(V=\phi, \rho, \omega)$, which produces some new strong phase associated with vector meson resonance and thus can cause relatively large CP asymmetry at the range of interferences. There are the resonances of $\phi \rightarrow K^{+}K^{-}$, $\rho \rightarrow K^{+}K^{-}$ and $\omega \rightarrow K^{+}K^{-}$ due to the mixing of vector mesons $\phi$, $\rho$, $\omega$. We calculate the CP asymmetry from the decay modes of $B \rightarrow KK\pi(K)$. Meanwhile, the localised CP asymmetries are presented and some detailed analysis can be found. The CP asymmetry from the decay mode of ${B}^{-}\rightarrow \phi\pi^{-}\rightarrow K^{+}K^{-}\pi^{-}$ is also presented in our framework which is well consisted with LHC experiment. The introduced CP asymmetry can provide a favorable theoretical support for the experimental exploration in the future.

9.Inclusive production of fully-charmed tetraquarks at LHC

Authors:Feng Feng, Yingsheng Huang, Yu Jia, Wen-Long Sang, De-Shan Yang, Jia-Yue Zhang

Abstract: The $X(6900)$ resonance, originally discovered by the \texttt{LHCb} collaboration and later confirmed by both \texttt{ATLAS} and \texttt{CMS} experiments, has sparked broad interests in the fully-charmed tetraquark states. Relative to the mass spectra and decay properties of fully-heavy tetraquarks, our knowledge on their production mechanism is still rather limited. In this work we investigate the inclusive production of fully-charmed $S$-wave tetraquarks at \texttt{LHC} within the nonrelativistic QCD (NRQCD) factorization framework. The partonic cross sections are computed at lowest order in $\alpha_s$ and velocity, while the long-distance NRQCD matrix elements are estimated from phenomenological potential models. We predict the differential $p_T$ spectra of various fully-charmed $S$-wave tetraquarks at the \texttt{LHC}, and compare with the results predicted from the fragmentation mechanism at large $p_T$ end.