Holographic models that consider classical vector fields in a 5-d background provide effective descriptions for heavy vector meson spectra. This is true both in vacuum and a thermal medium, such as quark gluon plasma. However, the manner in which these phenomenological models work is unclear. In particular, what is the role of the fifth dimension, and what is the relation between the holographic 5-d background and physical (4-d) heavy mesons? Hadrons, in contrast to leptons, are composite particles with some internal structure that depends on the energy at which they are observed. In this study, a static meson is represented by a heavy quark-antiquark pair with an interaction described by a Nambu Goto string existing in the same 5-d background that provides field solutions leading to masses and decay constants of charmonium states. The resulting interaction potential is linear for large distances, with a string tension consistent with the effective Cornell potential. Introducing temperature $\textit{T}$ in the background, it is found for the $J/\psi$ case that there is a deconfining transition at some critical value of $\textit{T}$. The obtained results indicate that the 5-d background effectively represents the internal structure of the (static) charmonium (quasi) states.

Brazil

Nelson R.F. Braga

Yan F. Ferreira

William S. Cunha

Holography and the internal structure of charmonium * The authors are partially supported by CNPq — Conselho Nacional de Desenvolvimento Científico e Tecnologico, by FAPERJ — Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro and by Coordenação de Aperfeiçoamento de Pessoal de Nível Superior — Brasil (CAPES), Finance Code 001

<p>Millicharged particles, proposed by various extensions of the standard model, can be created in pairs by high-energy photons within nuclear reactors and can interact electromagnetically with electrons in matter. Recently, the existence of a plasmon peak in the interaction cross section with silicon in the eV range was highlighted as a promising approach to enhance low-energy sensitivities. The CONNIE and Atucha-II reactor neutrino experiments utilize Skipper-CCD sensors, which enable the detection of interactions in the eV range. We present world-leading limits on the charge of millicharged particles within a mass range spanning 6 orders of magnitude, derived through a comprehensive analysis and the combination of data from both experiments.</p>

Mexico

Alexis A. Aguilar-Arevalo

Juan Carlos D’Olivo

Youssef Sarkis

Argentina

Nicolas Avalos

Xavier Bertou

Pablo Bellino

Carla Bonifazi

United States

Ana Botti

Gustavo Cancelo

Juan Estrada

Richard Ford

Kevin Kuk

Andrew Lathrop

Javier Tiffenberg

Austria

Mariano Cababié

Brenda A. Cervantes-Vergara

Paraguay

Claudio Chavez

Fernando Chierchie

David Delgado

Eliana Depaoli

João dos Anjos

Herman P. Lima

Guillermo Fernandez Moroni

Aldo R. Fernandes Neto

Switzerland

Ben Kilminster

Patrick Lemos

Katherine Maslova

Irina Nasteva

Ana Carolina Oliveira

Pedro Ventura

Martin Makler

Agustina Magnoni

Franciole Marinho

Jorge Molina

Diego Stalder

Santiago Perez

Dario Rodrigues

Laura Paulucci

Ivan Sidelnik

Miguel Sofo Haro

Search for Reactor-Produced Millicharged Particles with Skipper-CCDs at the CONNIE and Atucha-II Experiments

We study the basic integral equation in Lindhard’s theory describing the energy given to atomic motion by nuclear recoils in a pure material when the atomic binding energy is taken into account. The numerical solution, which depends only on the slope of the velocity-proportional electronic stopping power and the binding energy, leads to an estimation of the ionization efficiency which is in good agreement with the available experimental measurements for Si and Ge. In this model, the quenching factor for nuclear recoils features a cutoff at an energy equal to twice the assumed binding energy. We argue that the model is a reasonable approximation for Ge even for energies close to the cutoff, while for Si is valid up to recoil energies greater than <math><mo>∼</mo><mn>500</mn><mtext> </mtext><mtext> </mtext><mi>eV</mi></math>.

Y. Sarkis

Alexis Aguilar-Arevalo

Study of the ionization efficiency for nuclear recoils in pure crystals

The constituent quark model is used to compute the ground and excited state masses of QQQbaryons containing either c or bquarks. The quark model parameters previously used to describe the properties of charmonium and bottomonium states were used in this analysis. The non-relativistic three-body bound state problem is solved by means of the Gaussian expansion method which provides sufficient accuracy and simplifies the subsequent evaluation of the matrix elements. Several low-lying states with quantum numbers 
					 and 
					 are reported. We compare the results with those obtained by the other theoretical formalisms. There is a general agreement for the mass of the ground state in each sector of triply heavy baryons. However, the situation is more puzzling for the excited states, and appropriate comments about the most relevant features of our comparison are given.
				

China

Gang Yang

Jialun Ping

Spain

Pablo G. Ortega

Jorge Segovia

Triply heavy baryons in the constituent quark model Supported by China Postdoctoral Science Foundation (2019M650617), National Natural Science Foundation of China (11535005, 11775118), and by Spanish Ministerio de Economía, Industria y Competitividad under contractsno. FPA2017-86380-P and FPA2016-77177-C2-2-P. P.G.O. acknowledges the financial support from Spanish MINECO's Juan de la Cierva-Incorporación programme, Grant Agreement No. IJCI-2016-28525.