Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session T10: Field Theory IIRecordings Available
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Sponsoring Units: DPF Chair: Yannick Meurice, University of Iowa Room: Lyceum |
Monday, April 11, 2022 3:45PM - 3:57PM |
T10.00001: A Stable Sexaquark: Overview and Discovery Strategies Glennys R Farrar The neutral, flavor singlet scalar uuddss bound state – the sexaquark, S – may have a low enough mass to be stable or extremely long-lived. Here we review mass estimates and production expectations and show that laboratory experiments to date do not rule out such a long-lived state. An S with mass below 2054 MeV is either absolutely stable or has a lifetime greater than the age of the Universe. Detection of a stable S in accelerator experiments is very challenging. An examination of the experimental literature shows that such an effectively stable state would have escaped detection. The strongest laboratory constraint on a long-lived S comes from the lower-bound on its formation time in a doubly-strange hypernucleus; this constraint is, however, not stringent enough to exclude a stable S. We develop strategies to discover it. A stable S would be an attractive dark matter candidate. Relevant astrophysical and cosmological observations, which show that sexaquark dark matter (SDM) is consistent with all current knowledge, are briefly reviewed. |
Monday, April 11, 2022 3:57PM - 4:09PM |
T10.00002: Exploring phase behavior of the MDCDW condensate in dense quark matter with a magnetic field: Where astrophysics meets QCD Will Gyory, Vivian F Incera The problem of predicting states of quark matter and describing their properties at various temperatures and densities—known as mapping the QCD phase diagram—has been a major goal of theoretical and experimental research in recent years. The region of low temperatures and intermediate densities is of particular interest to astrophysics because these conditions are realized in the interiors of neutron stars. I will discuss a candidate state of matter that may arise in such environments, known as the magnetic dual chiral density wave (MDCDW), which is characterized by a spatially oscillating chiral condensate. Using a generalized Ginzburg-Landau expansion to explore the condensate’s phase behavior, we found that the presence of a magnetic field enhances the stability against thermal fluctuations and extends the parameter space in which the condensate is energetically favored. At sufficiently strong magnetic fields and within a range of low temperatures compatible with neutron star conditions, MDCDW remains favored over the symmetric ground state at all densities. Future research on this phase may reveal deep insights on the behavior of matter under these extreme conditions, paving the way for new collaborations between nuclear physics and multi-messenger astronomy. |
Monday, April 11, 2022 4:09PM - 4:21PM |
T10.00003: Meson-Glueball Mixing and Other Back-Reaction Effects in the Sakai-Sugimoto Model of AdS/QCD Nelia Mann, Sophia Domokos Top-down holographic QCD models often work in the probe approximation (also known as the quenched approximation), assuming that the number of colors is much greater than the number of flavors. Going beyond this approximation is essential to a fuller understanding of holography and more accurate phenomenological predictions. Even as multiple works venture to study particle mass spectra with some back-reaction effects included, meson-glueball mixing is a key effect in the quadratic order Lagrangian that has so far been largely neglected in the literature -- and aligns with phenomenological hypotheses that many low-lying meson states are in fact part glueball. In this talk, we describe the mixing between vector glueballs and scalar mesons arising from the DBI action in the Sakai-Sugimoto model of holographic QCD, and show that this mixing must be treated as a part of the back-reaction of the D8-branes onto the background geometry. Including this back-reaction with the simplification that it is ``smeared out'' over the compact transverse direction, we analyze first order corrections to the mass spectra of both the vector and scalar particles. We show that while the vector glueball masses are unaffected by the explicit mixing, this effect is the most significant back-reaction correction to the masses of low-lying scalar mesons. |
Monday, April 11, 2022 4:21PM - 4:33PM |
T10.00004: Effect of Electromagnetic Fields on Deformed AdS5 Models Davoud Masoumi, Leila Shahkarami, Farid Charmchi Many studies have investigated the vast aspects of the Schwinger effect by using gauge/gravity duality; however, the Schwinger effect in QCD-like gauge theories, especially where both electric and magnetic fields are simultaneously present, still need to be scrutinized. We use a deformed AdS5 background metric for the gravity side of AdS/QCD correspondence since the potential of heavy quarks produced by this background metric agrees with experimental data. We utilize both potential analysis and calculation of the pair-production rate Γ to study the response of the QCD-like gauge theory to an external electromagnetic field and show that the two approaches agree. We identify critical electric fields ES and EC as lower and upper bounds of a range in which pair production can occur only by tunneling through a potential barrier. Below ES, the potential barrier is insurmountable, and pair production cannot happen. Above EC, there is no potential barrier to restrict the pair production. In addition, we find that a magnetic field perpendicular to the electric field suppresses Γ and increases ES. In contrast, a pure parallel magnetic field does not affect the system's response to an external electric field, but it enhances Γ when a perpendicular magnetic field is also present. |
Monday, April 11, 2022 4:33PM - 4:45PM |
T10.00005: Resurgence as a new tool for computing inclusive hadronic observables in Quantum Chromodynamics Juan Carlos Vasquez Carmona, Alessio Maiezza We study the QCD Adler function in the energy region ≈0.7−2.5 GeV, in which the non-perturbative effects become dominant. Our analysis is a renormalon-based evaluation using transseries within the resurgence of the Renormalization-Group-Equation and does not require the Operator-Product-Expansion. |
Monday, April 11, 2022 4:45PM - 4:57PM |
T10.00006: A cosmologically consistent millicharged dark matter solution to the EDGES anomaly Amin Abou Ibrahim, Pran Nath Analysis of EDGES data shows an absorption signal of the redshifted 21-cm line of atomic hydrogen at z∼17 which is stronger than expected from the standard ΛCDM model at a 3.8σ deviation. We present a particle physics model for the baryon cooling where a fraction of the dark matter resides in the hidden sector with a U(1) gauge symmetry and a Stueckelberg mechanism operates mixing the visible and the hidden sectors with the hidden sector consisting of dark Dirac fermions and dark photons. The Stueckelberg mass mixing mechanism automatically generates a millicharge for the hidden sector dark fermions providing a theoretical basis for using millicharged dark matter to produce the desired cooling of baryons seen by EDGES by scattering from millicharged dark matter. We compute the relic density of the millicharged dark matter by solving a set of coupled equations for the dark fermion and dark photon yields and for the temperature ratio of the hidden sector and the visible sector heat baths. For the analysis of baryon cooling, we analyze the evolution equations for the temperatures of baryons and millicharged dark matter as a function of the redshift. We exhibit regions of the parameter space which allow consistency with the EDGES data. We note that the Stueckelberg mechanism arises naturally in strings and the existence of a millicharge would point to its string origin. |
Monday, April 11, 2022 4:57PM - 5:09PM |
T10.00007: Limits on Excess Neutron Number Production in a Pb-Target at 583 m.w.e. Underground Haichuan Cao, David S Koltick New physics processes, initiated by cosmic rays or though dark matter interactions may be observable by excess neutron number production within the neutron number spectrum measured using high-A nuclear targets. For this purpose, data has been collected and analyzed using the NMDS-II detector located at a depth of 220 m below sea-level, or 583 m.w.e. at the Center for Underground Physics in Pyhasalmi, CUPP, in Finland. The detector consists of a 30 cm, 305kg cubic lead target, instrumented with 60, He-3 neutron counters and a two-layer Geiger Counter system for the detection of muons. |
Monday, April 11, 2022 5:09PM - 5:21PM |
T10.00008: Geological quartz as a detector for ultra-heavy dark matter Reza Ebadi, Anubhav Mathur, Erwin Tanin, Nicholas Tailby, Mason C Marshall, Aakash Ravi, Raisa Trubko, Roger Fu, David F Phillips, Surjeet Rajendran, Ronald L Walsworth Despite extensive searches with ever-improving exclusion bounds, no dark matter candidate has yet been observed. This motivates searches for a wider range of possible dark sectors. Self-interactions within the dark sector could clump dark matter into heavy composite states with low number density, leading to a highly suppressed event rate for existing direct detection experiments. On the other hand, the large interaction cross section of such ultra-heavy dark matter results in a distinctive and compelling signature: macroscopically long, straight damage tracks as the composite dark matter passes through, and continuously scatters off, the surrounding matter. We propose using geologically old quartz samples as detectors for ultra-heavy dark matter. The advantage of this search strategy is two-fold: the age of the sample provides a large exposure time, and thus compensates for the ultra-heavy dark matter's low number density; and the unique geometry of the damage track serves as a high-fidelity background rejection tool. We present a high-resolution robust readout method based on electron microscopy, as well as a first characterization of the most favorable geological samples as detectors. We also demonstrate the reach of this search strategy in a simple QCD-like model of the dark sector. |
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