Mon·Jun 5, 2017Monday·June 5, 2017

1. 01*

   Exotics: Heavy Pentaquarks and Tetraquarks

   Ahmed Ali🇩🇪 · Jens Sören Lange🇩🇪 · Sheldon Stone🇺🇸

   For many decades after the invention of the quark model in 1964 there was no evidence that hadrons are formed from anything other than the simplest pairings of quarks and antiquarks, mesons being formed of a quark-antiquark pair and baryons from three quarks. In the last decade, however, in an explosion of data from both $e^{+}{e}^{-}$ and hadron colliders, there are many recently observed states that do not fit into this picture. These new particles are called generically "exotics". They can be either mesons or baryons. Remarkably, they all decay into at least one meson formed of either a $c\overline{c}$ or $b\overline{b}$ pair. In this review, after the introduction, we explore each of these new discoveries in detail first from an experimental point of view, then subsequently give a theoretical discussion. These exotics can be explained if the new mesons contain two-quarks and two-antiquarks (tetraquarks), while the baryons contain four-quarks plus an antiquark (pentquarks). The theoretical explanations for these states take three divergent tracks: tightly bound objects, just as in the case of normal hadrons, but with more constituents, or loosely bound "molecules" similar to the deuteron, but formed from two mesons, or a meson or baryon, or more wistfully, they are not multiquark states but appear due to kinematic effects caused by different rescatterings of virtual particles; most of these models have all been post-dictions. Both the tightly and loosely bound models predict the masses and related quantum numbers of new, as yet undiscovered states. Thus, future experimental discoveries are needed along with theoretical advances to elucidate the structure of these new exotic states.

   hep-phhep-exPPNP(2017)·686 citations
2. 02*

   Hadronic Higgs boson decay at order ${\alpha }_s^4$ and ${\alpha }_s^5$

   Joshua Davies🇩🇪 · Matthias Steinhauser🇩🇪 · David Wellmann🇩🇪

   We compute corrections to the decay of the Standard Model Higgs boson to hadrons, to the fourth order in the strong coupling constant ${\alpha }_s$. We use an effective theory in which the Higgs boson couples directly to bottom quarks and to gluons, via top quark--mediated effective couplings. Numerically, our results are of a comparable size to the previously-known "massless" contributions and complete the order ${\alpha }_s^4$ corrections to the hadronic decay of the Higgs boson. In these proceedings we also provide an independent cross check of the gluonic Higgs boson decay at order ${\alpha }_s^5$.

   hep-phPoS(2018)·10 citations
3. 03*

   (Higgs) vacuum decay during inflation

   Aris Joti🇬🇷 · Aris Katsis🇬🇷 · Dimitris Loupas🇬🇷 · Alberto Salvio🇨🇭 · Alessandro Strumia🇨🇭 · Nikolaos Tetradis🇬🇷 · Alfredo Urbano🇨🇭

   We develop the formalism for computing gravitational corrections to vacuum decay from de Sitter space as a sub-Planckian perturbative expansion. Non-minimal coupling to gravity can be encoded in an effective potential. The Coleman bounce continuously deforms into the Hawking-Moss bounce, until they coincide for a critical value of the Hubble constant. As an application, we reconsider the decay of the electroweak Higgs vacuum during inflation. Our vacuum decay computation reproduces and improves bounds on the maximal inflationary Hubble scale previously computed through statistical techniques.

   hep-phgr-qchep-thJHEP(2017)·66 citations
4. 04*

   Multi-flavor effects in Stimulated Transitions of Neutrinos

   Y. Yang🇨🇳 · J. P. Kneller🇺🇸 · K. M. Perkins🇺🇸

   A neutrino subject to an external, time-dependent perturbing potential can be forced to make transitions between its flavor states. A neutrino with three (or more) flavors can exhibit phenomena that cannot occur if the neutrino had just two. We present an approximate analytic solution for the temporal evolution of a multi-flavor neutrino in response to an arbitrary perturbing Hamiltonian that has been decomposed into its Fourier modes. We impose no restriction upon the number of flavors nor upon the structure of the perturbing Hamiltonian, the number of Fourier modes, their amplitude or their frequencies. We apply the theory to study three-flavor neutrino transformation due to perturbations built from two and three Fourier modes. For the case of two Fourier modes we observe the equivalent of "induced transparency" from quantum optics whereby transitions between a given pair of states are suppressed due to the presence of a resonant mode between another pair. When we add a third Fourier mode we find a new effect whereby the third mode can manipulate the transition probabilities of the two mode case so as to force complete transparency or, alternatively, restore "opacity" meaning the perturbative potential regains its ability to induce neutrino transitions. In both applications we demonstrate how the analytic solutions are able to match the amplitude and wavenumber of the numerical results to within a few percent.

   hep-phastro-ph.HE1 citation
5. 05*

   Critical point in the phase diagram of primordial quark-gluon matter from black hole physics

   Renato Critelli (1)🇧🇷 · Jorge Noronha (1)🇧🇷 · Jacquelyn Noronha-Hostler (2,3)🇺🇸 · Israel Portillo (3)🇺🇸 · Claudia Ratti (3)🇺🇸 · Romulo Rougemont (4) ((1) Sao Paulo U., (2) Rutgers U., (3) Houston U., (4) IIP, Brazil)🇧🇷

   Strongly interacting matter undergoes a crossover phase transition at high temperatures $T\sim 10^{12}$ K and zero net-baryon density. A fundamental question in the theory of strong interactions, Quantum Chromodynamics (QCD), is whether a hot and dense system of quarks and gluons displays critical phenomena when doped with more quarks than antiquarks, where net-baryon number fluctuations diverge. Recent lattice QCD work indicates that such a critical point can only occur in the baryon dense regime of the theory, which defies a description from first principles calculations. Here we use the holographic gauge/gravity correspondence to map the fluctuations of baryon charge in the dense quark-gluon liquid onto a numerically tractable gravitational problem involving the charge fluctuations of holographic black holes. This approach quantitatively reproduces ab initio results for the lowest order moments of the baryon fluctuations and makes predictions for the higher order baryon susceptibilities and also for the location of the critical point, which is found to be within the reach of heavy ion collision experiments.

   ↳ nucl-thhep-lathep-phhep-th+1PRD(2017)·197 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.