Fri·May 25, 2018Friday·May 25, 2018

1. 01*

   Diffractive electron-nucleus scattering and ancestry in branching random walks

   A. H. Mueller🇺🇸 · S. Munier🇫🇷

   We point out an analogy between diffractive electron-nucleus scattering events, and realizations of one-dimensional branching random walks selected according to the height of the genealogical tree of the particles near their boundaries. This correspondence is made transparent in an event-by-event picture of diffraction emphasizing the statistical properties of gluon evolution, from which new quantitative predictions straightforwardly follow: we are able to determine the distribution of the total invariant mass produced diffractively, which is an interesting observable that can potentially be measured at a future electron-ion collider.

   hep-phcond-mat.dis-nncond-mat.stat-mechPRL(2018)·15 citations
2. 02*

   Sea quark Sivers distribution

   Hui Dong🇨🇳 · Du-xin Zhen · Jian Zhou🇨🇳

   We compute sea quark Sivers distribution within color glass condensate(CGC) framework. It has been found that up to the leading logarithm accuracy, the collinear twist-3 approach and the CGC calculation yield the same result for sea quark Sivers distribution in the dilute limit. We further verify that transverse momentum dependent factorization is consistent with CGC treatment at small $x$ for the case of transverse spin asymmetry in open charm quark production in semi-inclusive deeply inelastic scattering process in an overlap kinematical region.

   hep-phPLB(2019)·33 citations
3. 03*

   A potential scenario for the Majorana neutrino detection at future lepton colliders

   Yang Zhang🇨🇳 · Bin Zhang🇨🇳

   The existence of Majorana neutrinos must lead to lepton-number violating processes, and the Majorana nature of neutrinos can only be experimentally verified via lepton-number violating processes. We propose a new approach to search for Majorana neutrinos at future electron-positron colliders by exploiting this feature. We investigate the $\Delta L=2$ like-sign dilepton production and find that lepton colliders with different center-of-mass energies have comparative advantages in resonant production of a Majorana neutrino in either light neutrino mass range or heavy mass range. At the future Circular Electron-Positron Collider (CEPC), with 250 GeV center-of-mass energy and 5 ab${}^{-1}$ integrated luminosity, we find that there could be more significant sensitivity for resonant production of a Majorana neutrino in the mass range of 5-80 GeV than previous results at LEP2 or LHC. At the 1 TeV ILC with 1 ab${}^{-1}$ integrated luminosity, it has better sensitivity than the similar process at LHC while the neutrino mass is larger than 250 GeV.

   hep-phJHEP(2019)·14 citations
4. 04*

   About electrodynamics, standard model and the quantization of the electrical charge

   Renata Jora🇷🇴

   The quantization of the electrical charge in the electrodynamics and of the hypercharge in the standard model are imposed in the theory based not on theoretical arguments but on the experimental observations. In this paper we propose a quantum consistency condition in a theory where Ward identities are respected that requires the quantization of the charge within the framework of the theory without external impositions. This refers to the renormalization conditions in the background gauge field method such that to ensure a correct mathematical correspondence between the bare partition function and the renormalized one. Applied to the standard model of elementary particles our criterion together with the anomaly cancellation condition leads to the correct hypercharge assignment of all standard model fermions.

   hep-phInt.J.Mod.Phys.A(2018)·2 citations
5. 05*

   Charged Lepton Mass Relations in a SUSY Scenario

   Yoshio Koide🇯🇵 · Toshifumi Yamashita🇯🇵

   The observed charged lepton masses satisfy the relations $K\equiv (m_e+m_{\mu }+m_{\tau })/(\sqrt{m_e}+\sqrt{m_{\mu }}+\sqrt{m_{\tau }}{)}^2=2/3$ and $\kappa \equiv \sqrt{m_e{m}_{\mu }{m}_{\tau }}/(\sqrt{m_e}+\sqrt{m_{\mu }}+\sqrt{m_{\tau }}{)}^3=1/486$ with great accuracy. These parameters are given as $K=(\mathrm{Tr}[\Phi \Phi ])/(\mathrm{Tr}[\Phi ]{)}^2$ and $\kappa =\det \Phi /(\mathrm{Tr}[\Phi ]{)}^3$ if the charged lepton masses $m_{ei}$ are given by $m_{ei}\propto {\sum }_k{\Phi }_i^k{\Phi }_k^i$ where $\Phi$ is a U(3)-family nonet scalar. Simple scalar potential forms to realize the relations have been already proposed in non-supersymmetric scenarios, but the potential forms are not stable against the renormalization group effects. In this paper, we examine supersymmetric scenarios and find that the parameters $K$ and $\kappa$ are made stable against the effects in a very nontrivial way, even though the superpotential itself (in the canonical basis) suffers the usual corrections. We also show possible simple superpotential forms for the relations.

   hep-phPLB(2018)·4 citations
6. 06*

   Study of $CP$ Violations in $B^{-}\to K^{-}{\pi }^{+}{\pi }^{-}$ and $B^{-}\to K^{-}{f}_0(500)$ decays in the QCD factorization approach

   Jing-Juan Qi🇨🇳 · Zhen-Yang Wang🇨🇳 · Zhen-Hua Zhang🇨🇳 · Jing Xu🇨🇳 · Xin-Heng Guo🇨🇳

   Within the QCD factorization approach, we study the $CP$ violations in $B^{-}\to K^{-}{\pi }^{+}{\pi }^{-}$ and $B^{-}\to K^{-}{f}_0(500)$ decays. We find the experimental data of the localized $CP$ asymmetry in $B^{-}\to K^{-}{\pi }^{+}{\pi }^{-}$ decays in the region $m_{K^{-}{\pi }^{+}}^2<15$ ${\mathrm{GeV}}^2$ and $0.08<m_{{\pi }^{+}{\pi }^{-}}^2<0.66$ ${\mathrm{GeV}}^2$ can be explained by the interference of two intermediate resonances, ${\rho }^0(770)$ and $f_0(500)$ when the parameters in our interference model are in the allowed ranges, i.e. the relative strong phase $\delta \in [0,1.745]\cup [3.578,6.266]$ and the end-point divergence parameters ${\rho }_S\in [2.790,5.290]$ and ${\varphi }_S\in [1.518,5.183]$. With the obtained allowed ranges for ${\rho }_S$ and ${\varphi }_S$, we obtain the predictions for the $CP$ asymmetry parameter $A_{CP}\in [-0.259,0.006]$ and the branching fraction $\mathcal{B}\in [0.585,3.230]\times 10^{-5}$ for $B^{-}\to K^{-}{f}_0(500)$ decay modes.

   hep-phEPJC(2018)·9 citations
7. 07*

   Electric dipole moments and dark matter in a CP violating MSSM

   Tomohiro Abe🇯🇵 · Naoya Omoto🇯🇵 · Osamu Seto🇯🇵 · Tetsuo Shindou🇯🇵

   We investigate electric dipole moments (EDMs) in a CP-violating minimal supersymmetric standard model with the Bino-like neutralino dark matter (DM) annihilating through the heavy Higgs funnel. Motivated by the current experimental results, in particular, the measured mass of the standard model-like Higgs boson, we consider a mass spectrum with stop masses of about 10 TeV. For the other sfermions, we consider masses of about 100 TeV. We show that CP-violating phases of the order of ten degrees in gaugino and Higgsino mass parameters are consistent with the current bound by EDMs of the electron, the neutron, and the mercury. They are within the reach of future experiments. We also show that effects of CP-violating phases induce a difference in DM-nucleon scattering cross section by a factor.

   hep-phPRD(2018)·12 citations
8. 08*

   Magnetic moments of the spin-$\frac{3}{2}$ singly heavy baryons

   Lu Meng🇨🇳 · Guang-Juan Wang🇨🇳 · Chang-Zhi Leng🇨🇳 · Zhan-Wei Liu🇨🇳 · Shi-Lin Zhu🇨🇳

   We calculate the magnetic moments of spin-$\frac{3}{2}$ singly charmed baryons in the heavy baryon chiral perturbation theory (HBChPT). The analytical expressions are given up to $\mathcal{O}(p^3)$. The heavy quark symmetry is used to reduce the number of low energy constants (LECs). With the lattice QCD simulation data as the magnetic moments of the charmed baryons, the numerical results are given up to $\mathcal{O}(p^3)$ in three scenarios. In the first scenario, we use the results in the quark model as the leading order input. In the second scenario, we use the heavy quark symmetry and neglect the contribution of heavy quark. In the third scenario, the heavy quark contribution is considered on the basis of the scenario II and the magnetic moments of singly bottom baryons are given as a by-product.

   hep-phhep-exhep-latnucl-thPRD(2018)·24 citations
9. 09*

   Multi-period structure of electro-weak phase transition in the 3-3-1-1 model

   Vo Quoc Phong🇻🇳 · N. T. Tuong🇻🇳 · N. C. Thao🇻🇳 · H. N. Long🇻🇳

   The electroweak phase transition (EWPT) is considered in the framework of 3-3-1-1 model for Dark Matter. The phase structure within three or two periods is approximated for the theory with many vacuum expectation values (VEVs) at TeV and Electroweak scales. In the mentioned model, there are two pictures. The first picture containing two periods of EWPT, has a transition $SU(3)\to SU(2)$ at 6 TeV scale and another is $SU(2)\to U(1)$ transition which is the like-standard model EWPT. The second picture is an EWPT structure containing three periods, in which two first periods are similar to those of the first picture and another one is the symmetry breaking process of $U(1{)}_N$ subgroup. Our study leads to the conclusion that EWPTs are the first order phase transitions when new bosons are triggers and their masses are within range of some TeVs. Especially, in two pictures, the maximum strength of the $SU(2)\to U(1)$ phase transition is equal to 2.12 so this EWPT is not strong. Moreover, neutral fermions, which are candidates for Dark Matter and obey the Fermi-Dirac distribution, can be a negative trigger for EWPT. However, they do not make lose the first-order EWPT at TeV scale. Furthermore, in order to be the strong first-order EWPT at TeV scale, the symmetry breaking processes must produce more bosons than fermions or the mass of bosons must be much larger than that of fermions.

   hep-phPRD(2019)·9 citations
10. 10*

    Axion mass in the case of post-inflationary Peccei-Quinn symmetry breaking

    Andreas Ringwald🇩🇪

    The axion not only solves the strong CP puzzle, but it also may be the main constituent of cold dark matter. We review the axion dark matter predictions for the case that the Peccei-Quinn symmetry is restored after inflation.

    hep-phastro-ph.COhep-ex6 citations
11. 11*

    On quartic colour factors in splitting functions and the gluon cusp anomalous dimension

    S. Moch (Hamburg U., Inst. Theor. Phys. II)🇩🇪 · B. Ruijl (Zurich, ETH)🇨🇭 · T. Ueda (Seikei U.)🇯🇵 · J.A.M. Vermaseren (NIKHEF, Amsterdam)🇳🇱 · A. Vogt (Liverpool U., Dept. Math.)🇬🇧

    We have computed the contributions of the quartic Casimir invariants to the four-loop anomalous dimensions of twist-2 spin-N operators at N =< 16. The results provide new information on the structure of the next-to-next-to-next-to-leading order (N^3LO) splitting functions P_{ik}^(3)(x) for the evolution of parton distributions, and facilitate approximate expressions which include the quartic-Casimir contributions to the (light-like) gluon cusp anomalous dimension. These quantities turn out to be closely related, by a generalization of the lower-order `Casimir scaling', to the corresponding quark results. Using these findings, we present an approximate result for the four-loop gluon cusp anomalous dimension in QCD which is sufficient for phenomenological applications.

    hep-phPLB(2018)·166 citations
12. 12*

    Gauge Properties of Hadronic Structure of Nucleon in Neutron Radiative Beta Decay to Order O(alpha/pi) in Standard V - A Effective Theory with QED and Linear Sigma Model of Strong Low--Energy Interactions

    A. N. Ivanov🇦🇹 · R. Höllwieser🇦🇹 · N. I. Troitskaya🇦🇹 · M. Wellenzohn🇦🇹 · Ya. A. Berdnikov🇷🇺

    Within the standard V - A theory of weak interactions, Quantum Electrodynamics (QED) and the linear sigma-model (LsM) of strong low-energy hadronic interactions we analyse gauge properties of hadronic structure of the neutron and proton in the neutron radiative beta-decay. We show that the Feynman diagrams, describing contributions of hadronic structure to the amplitude of the neutron radiative beta-decay in the tree-approximation for strong low-energy interactions in the LsM, are gauge invariant. In turn, the complete set of Feynman diagrams, describing the contributions of hadron-photon interactions in the one-hadron-loop approximation, is not gauge invariant. In the infinite limit of the scalar sigma-meson, reproducing the current algebra results (Weinberg, Phys. Rev. Lett. 18, 188 (1967)), and to leading order in the large nucleon mass expansion the Feynman diagrams, violating gauge invariance, do not contribute to the amplitude of the neutron radiative beta-decay in agreement with Sirlin's analysis of strong low-energy interactions in neutron beta decays. We assert that the problem of appearance of gauge non-invariant Feynman diagrams of hadronic structure of the neutron and proton is related to the following. The vertex of the effective V-A weak interactions does not belong to the combined quantum field theory including the LsM and QED. We argue that gauge invariant set of Feynman diagrams of hadrons, coupled to real and virtual photons in neutron beta decays, can be obtained within the combined quantum field theory including the Standard Electroweak Model (SEM) and the LsM, where the effective V-A vertex of weak interactions is a result of the W^- - electroweak boson exchange.

    hep-phgr-qcnucl-exInt.J.Mod.Phys.A(2018)·8 citations
13. 13*

    Consistent Conformal Extensions of the Standard Model

    Florian Loebbert🇩🇪 · Julian Miczajka🇩🇪 · Jan Plefka🇩🇪

    The question of whether classically conformal modifications of the standard model are consistent with experimental obervations has recently been subject to renewed interest. The method of Gildener and Weinberg provides a natural framework for the study of the effective potential of the resulting multi-scalar standard model extensions. This approach relies on the assumption of the ordinary loop hierarchy ${\lambda }_{\text{s}}\sim g_{\text{g}}^2$ of scalar and gauge couplings. On the other hand, Andreassen, Frost and Schwartz recently argued that in the (single-scalar) standard model, gauge invariant results require the consistent scaling ${\lambda }_{\text{s}}\sim g_{\text{g}}^4$. In the present paper we contrast these two hierarchy assumptions and illustrate the differences in the phenomenological predictions of minimal conformal extensions of the standard model.

    hep-phhep-thPRD(2019)·19 citations
14. 14*

    Effects of the ghost sector in gluon mass dynamics

    A. C. Aguilar🇧🇷 · C. T. Figueiredo🇧🇷

    In this work, we investigate the effects of the ghost sector on the dynamical mass generation for the gauge boson of a pure Yang-Mills theory. The generation of a dynamical mass for the gluon is realized by the Schwinger mechanism, which is triggered by the existence of longitudinally coupled massless poles in the fundamental vertices of the theory. The appearance of such poles occurs by purely dynamical reasons and is governed by a set of Bethe-Salpeter equations. In previous studies, only the presence of massless poles in the background-gauge three-gluon vertex was considered. Here, we include the possibility for such poles to appear also in the corresponding ghost-gluon vertex. Then, we solve the resulting Bethe-Salpeter system, which reveals that the contribution associated with the poles of the ghost-gluon vertex is suppressed with respect to those originating from the three-gluon vertex.

    hep-ph0 citations
15. 15*

    Quarkonium radiative decays from the hadronic Paschen-Back effect

    Sachio Iwasaki🇯🇵 · Kei Suzuki🇯🇵

    We study the radiative (E1 and M1) decays of P-wave quarkonia in a strong magnetic field based on the Lagrangian of potential nonrelativistic QCD. To investigate their properties, we implement a polarized wave function basis justified in the Paschen-Back limit. In a magnetic field stronger than the spin-orbit coupling, the wave functions of the P-wave quarkonia are drastically deformed by the Hadronic Paschen-Back effect. Such deformation leads to the anisotropy of the direction of decays from the P-wave quarkonia. The analytic formulas for the radiative decay widths in the nonrelativistic limit are shown, and the qualitative decay properties are discussed.

    hep-phhep-exnucl-exnucl-thPRD(2018)·13 citations
16. 16*

    Uncertainties in WIMP Dark Matter Scattering Revisited

    John Ellis🇬🇧 · Natsumi Nagata🇯🇵 · Keith A. Olive🇺🇸

    We revisit the uncertainties in the calculation of spin-independent scattering matrix elements for the scattering of WIMP dark matter particles on nuclear matter. In addition to discussing the uncertainties due to limitations in our knowledge of the nucleonic matrix elements of the light quark scalar densities < N |{\bar u} u, {\bar d} d, {\bar s} s| N>, we also discuss the importances of heavy quark scalar densities < N |{\bar c} c, {\bar b} b, {\bar t} t| N >, and comment on uncertainties in quark mass ratios. We analyze estimates of the light-quark densities made over the past decade using lattice calculations and/or phenomenological inputs. We find an uncertainty in the combination < N |{\bar u} u + {\bar d} d | N > that is larger than has been assumed in some phenomenological analyses, and a range of < N |{\bar s} s| N > that is smaller but compatible with earlier estimates. We also analyze the importance of the {\cal O}(\alpha_s^3) calculations of the heavy-quark matrix elements that are now available, which provide an important refinement of the calculation of the spin-independent scattering cross section. We use for illustration a benchmark CMSSM point in the focus-point region that is compatible with the limits from LHC and other searches.

    hep-phastro-ph.COhep-exEPJC(2018)·88 citations
17. 17*

    Hexapod Coloron at the LHC

    Yang Bai🇺🇸 · Sida Lu🇺🇸 · Qian-Fei Xiang🇨🇳

    Instead of the usual dijet decay, the coloron may mainly decay into its own "Higgs bosons", which subsequently decay into many jets. This is a general feature of the renormalizable coloron model, where the corresponding "Higgs bosons" are a color-octet $\Theta$ and a color-singlet ${\varphi }_I$. In this paper, we perform a detailed collider study for the signature of $pp\to G^{\prime }\to (\Theta \to gg)({\varphi }_I\to ggq\bar{q})$ with the coloron $G^{\prime }$ as a six-jet resonance. For a light ${\varphi }_I$ below around 0.5 TeV, it may be boosted and behave as a four-prong fat jet. We also develop a jet-substructure-based search strategy to cover this boosted ${\varphi }_I$ case. Independent of whether ${\varphi }_I$ is boosted or not, the 13 TeV LHC with 100 fb${}^{-1}$ has great discovery potential for a coloron with the mass sensitivity up to 5 TeV.

    hep-phhep-exJHEP(2018)·5 citations
18. 18*

    Quantum Decoherence Effects in Neutrino Oscillations at DUNE

    G. Balieiro Gomes🇧🇷 · D. V. Forero🇧🇷 · M. M. Guzzo🇧🇷 · P. C. de Holanda🇧🇷 · R. L. N. Oliveira🇧🇷

    In this work we analyze quantum decoherence in neutrino oscillations considering the Open Quantum System framework and oscillations through matter for three neutrino families. Taking DUNE as a case study we performed sensitivity analyses for two neutrino flux configurations finding limits for the decoherence parameters. We also offer a physical interpretation for a new peak which arises at the ${\nu }_e$ appearance probability with decoherence. The best sensitivity regions found for the decoherence parameters are ${\Gamma }_{21}\le 1.2\times 10^{-23}\text{GeV}$ and ${\Gamma }_{32}\le 7.7\times 10^{-25}\text{GeV}$ at $90\%$ C. L.

    hep-phhep-exPRD(2019)·57 citations
19. 19*

    Implications of a Dark Matter-Neutrino Coupling at Hyper-Kamiokande

    Andres Olivares-Del Campo🇬🇧 · Sergio Palomares-Ruiz🇪🇸 · Silvia Pascoli🇬🇧

    Dark matter and neutrinos provide the two most compelling pieces of evidence for new physics beyond the Standard Model of Particle Physics but they are often treated as two different sectors. In this paper, we consider how neutrino observables can be used to constrain the parameter space of different models where active neutrinos interact with DM via mediators of different spins. We study for the first time the sensitivity of the Hyper-Kamiokande detector to neutrinos produced from MeV Dark Matter annihilation. In particular, we find that thermally produced DM candidates with masses between 15-30 MeV could be fully excluded.

    hep-ph28 citations
20. 20*

    The $a_0(980)$ physics in semileptonic $D^0$ and $D^{+}$ decays

    N.N. Achasov🇷🇺 · A.V. Kiselev🇷🇺

    The decays $D^0\to d\bar{u}{e}^{+}\nu \to a_0^{-}(980)e^{+}\nu \to {\pi }^{-}\eta e^{+}\nu$ and $D^{+}\to d\bar{d}{e}^{+}\nu \to a_0^0(980)e^{+}\nu \to {\pi }^0\eta e^{+}\nu$ (and the charge conjugated ones) is the direct probe of the two-quark components in the $a_0^{\pm }(980)$ and $a_0^0(980)$ wave functions. Recent BESIII experiment is the first step in experimental study of these decays. We present a possible variant of $\eta \pi$ invariant mass distribution when $a_0(980)$ has no $q\bar{q}$ component at all.

    hep-phhep-exnucl-thPRD(2018)·14 citations
21. 21*

    Formation of topological vortices during superfluid transition in a rotating vessel

    Shreyansh S. Dave🇮🇳 · Ajit M. Srivastava🇮🇳

    Formation of topological defects during symmetry breaking phase transitions via the {\it Kibble mechanism} is extensively used in systems ranging from condensed matter physics to the early stages of the universe. Kibble mechanism uses topological arguments and predicts equal probabilities for the formation of defects and anti-defects. Certain situations, however, require a net bias in the production of defects (or antidefects) during the transition, for example, superfluid transition in a rotating vessel, or flux tubes formation in a superconducting transition in the presence of external magnetic field. In this paper we present a modified Kibble mechanism for a specific system, ${}^4$He superfluid transition in a rotating vessel, which can produce the required bias of vortices over antivortices. Our results make distinctive predictions which can be tested in superfluid ${}^4$He experiments. These results also have important implications for superfluid phase transitions in rotating neutron stars and also for any superfluid phases of QCD arising in the non-central low energy heavy-ion collision experiment due to an overall rotation.

    ↳ cond-mat.otherastro-ph.COhep-phhep-th+1EPL(2019)·2 citations
22. 22*

    The Stern-Gerlach Experiment and the Electron Spin

    Sandip Pakvasa (University of Hawaii)🇺🇸

    The full story of the Stern-Gerlach experiment and its reception, interpretation and final understanding has many unexpected surprises. Here, we review the history and the context of the proposal, the experiment, and the subsequent story of the aftermath. We also discuss the story of the possible Stern-Gerlach experiment for free electrons etc. Finally, we comment on the remarkable career of Otto Stern.

    ↳ physics.hist-phhep-ph2 citations
23. 23*

    Bruno Touschek and AdA: from Frascati to Orsay. In memory of Bruno Touschek, who passed away 40 years ago, on May 25th, 1978

    Luisa Bonolis🇩🇪 · Giulia Pancheri🇮🇹

    The first electron-positron collisions in a laboratory were observed in 1963-1964 at the Laboratoire de l'Accélérateur Linéaire d'Orsay, in France, with the storage ring AdA, which had been constructed in the Italian National Laboratories of Frascati in 1960, under the guidance of Bruno Touschek. The making of the collaboration between the two laboratories included visits between Orsay and Frascati, letters between Rome and Paris, and culminated with AdA leaving Frascati on July 4th, 1962 to cross the Alps on a truck, with the doughnut degassed to $10^{-9}$mmHg through pumps powered by sets of heavy batteries. This epoch-making trip and the exchanges which preceded it are described through unpublished documents and interviews with some of its protagonists, Carlo Bernardini, Francois Lacoste, Jacques Haïssinski, Maurice Lévy.

    ↳ physics.hist-phhep-exhep-ph11 citations
24. 24*

    On BPS World Volume, RR Couplings and their ${\alpha }^{\prime }$ Corrections in type IIB

    Ehsan Hatefi🇮🇹

    We compute the asymmetric and symmetric correlation functions of a four point amplitude of a gauge field, a scalar field and a closed string Ramond-Ramond (RR) for different non-vanishing BPS branes. All world volume, Taylor and pull-back couplings and their all order ${\alpha }^{\prime }$ corrections have also been explored. Due to various symmetry structures, different restricted BPS Bianchi identities have also been constructed. The prescription of exploring all the corrections of two closed string RR couplings in type IIB is given. We obtain the closed form of the entire S-matrix elements of two closed string RR and a gauge field on the world volume of BPS branes in type IIB. All the correlation functions of $<V_{A^0(x_1)}{V}_{C^{-1}(z_1,{\bar{z}}_1)}{V}_{C^{-1}(z_2,{\bar{z}}_2)}>$ are also revealed accordingly. The algebraic forms for the most general case of the integrations $\int d^{2}z|z-i{|}^a|z+i{|}^b(z-\bar{z}{)}^c(z+\bar{z}{)}^d$ on upper half plane are derived in terms of Pochhammer and some analytic functions. Lastly, we generate various singularity structures in both effective field theory and IIB string theory, producing different contact interactions as well as their ${\alpha }^{\prime }$ higher derivative corrections.

    ↳ hep-thgr-qchep-phAdv.High Energy Phys.(2020)·1 citation
25. 25*

    Primordial Black Holes from $\alpha$-attractors

    Ioannis Dalianis🇬🇷 · Alex Kehagias🇬🇷 · George Tringas🇬🇷

    We consider primordial black hole (PBH) production in inflationary $\alpha$-attractors. We discuss two classes of models, namely models with a minimal polynomial superpotential as well as modulated chaotic ones that admit PBHs. We find that a significant amplification of the curvature power spectrum ${\mathcal{P}}_{\mathcal{R}}$ can be realized in this class of models with a moderate tuning of the potential parameters. We consistently examine the PBH formation during radiation and additionally during reheating eras where the background pressure is negligible. It is shown that basic features of the curvature power spectrum are explicitly related with the postinflationary cosmic evolution and that the PBH mass and abundance expressions are accordingly modified. PBHs in the mass range $10^{-16}-10^{-14}{M}_{\odot }$ can form with a cosmologically relevant abundance for a power spectrum peak ${\mathcal{P}}_{\mathcal{R}}\sim 10^{-2}$ and large reheating temperature and, furthermore, for a moderate peak ${\mathcal{P}}_{\mathcal{R}}\sim 10^{-5}$ and reheating temperature $T_{\text{rh}}\sim 10^7$ GeV, characteristic of the position of the power spectrum peak. Regarding the CMB observables, the $\alpha$-attractor models utilized here to generate PBH in the low-mass region predict in general a smaller $n_s$ and larger $r$ and ${\alpha }_s$ parameter values compared to the conventional inflationary $\alpha$-attractor models.

    ↳ astro-ph.COgr-qchep-phhep-thJCAP(2019)·241 citations
26. 26*

    Holography of Low-Centrality Heavy Ion Collisions

    Brett McInnes🇸🇬

    Large vorticities in the Quark-Gluon Plasma produced in peripheral collisions studied by the STAR collaboration at the RHIC facility have been deduced from observations of polarizations of $\Lambda$ and $\overline{\Lambda }$ hyperons. Recently, the STAR collaboration has reported on the dependence of these polarizations on centrality, at impact energy 200 GeV and relatively large centralities $\mathcal{C}\ge 20\%$. The polarizations increase slowly with centrality, up to perhaps $\mathcal{C}=60-70\%$. Here we use a holographic model of the vortical QGP to make predictions regarding these polarizations for smaller centralities, ranging from $5-20\%$. The model predicts that as one moves downwards from $20\%$, $\Lambda /\overline{\Lambda }$ polarizations at first decrease but then \emph{increase} sharply, in a characteristic pattern which should be readily detected if collisions can be studied at impact energies below 200 GeV and centrality as low as $5-10\%$. The effect should be most evident at moderate impact energies below 200 GeV, so we give predictions for impact energy 27 GeV.

    ↳ hep-thgr-qchep-phInt.J.Mod.Phys.A(2019)·10 citations
27. 27*

    The cathode tube effect: heavy quarks probing the Glasma in p-Pb collisions

    Marco Ruggieri🇨🇳 · Santosh K. Das🇨🇳

    We study the propagation of charm quarks in the early stage of high energy proton-lead collision, considering the interaction of these quarks with the evolving Glasma by means of the Wong equations. Neglecting quantum fluctuations at the initial time the Glasma is made of longitudinal fields, but the dynamics leads to a quick formation of transverse fields; we estimate such a formation time as $\Delta t\approx 0.1$ fm/c which is of the same order of the formation time of heavy quark pairs $t_{\mathrm{formation}}\approx 1/(2m)$. Limiting ourselves to the simple case of a static longitudinal geometry, we find that heavy quarks are accelerated by the strong transverse color fields in the early stage and this leads to a tilting of the $c-$quarks spectrum towards higher $p_T$ states. This average acceleration can be understood in terms of drag and diffusion of $c-$quarks in a hot medium and appears to be similar to the one felt by the electrons ejected by the electron cannon in a cathode tube: we dub this effect as {\it cathode tube effect}. The tilting of the spectrum affects the nuclear modification factor, $R_{\mathrm{pPb}}$, suppressing this below one at low $p_T$ and making it larger than one at intermediate $p_T$. We compute $R_{\mathrm{pPb}}(p_T)$ after the evolution of charm quarks in the gluon fields and we find that its shape is in qualitative agreement with the measurements of the same quantity for $D-$mesons in proton-lead collisions.

    ↳ nucl-thhep-phnucl-exPRD(2018)·55 citations
28. 28*

    Brans-Dicke gravity: from Higgs physics to (dynamical) dark energy

    Joan Sola🇪🇸

    The Higgs mechanism is one of the central pieces of the Standard Model of electroweak interactions and thanks to it we can generate the masses of the elementary particles. Its fundamental origin is nonetheless unknown. Furthermore, in order to preserve renormalizability we have to break the gauge symmetry spontaneously, what leads to a huge induced cosmological constant incompatible with observations. It turns out that in the context of generalized Brans-Dicke theories of gravity the Higgs potential structure can be motivated from solutions of the field equations which carry harmless cosmological vacuum energy. In addition, the late time cosmic evolution effectively appears like an universe filled with mildly evolving dynamical dark energy mimicking quintessence or phantom dark energy.

    ↳ gr-qcastro-ph.COhep-phhep-thInt.J.Mod.Phys.D(2018)·34 citations
29. 29*

    Matter-antimatter asymmetry and other cosmological puzzles via running vacuum cosmologies

    J.A.S Lima🇧🇷 · Douglas Singleton🇺🇸

    Current astronomical observations are successfully explained by the present cosmological paradigm based on the concordance model (${\Lambda }_0$CDM + Inflation). However, such a scenario is composed of a heterogeneous mix of ingredients for describing the different stages of cosmological evolution. Particularly, it does not give an unified explanation connecting the early and late time accelerating inflationary regimes which are separated by many aeons. Other challenges to the concordance model include: a singularity at early times or the emergence of the Universe from the quantum gravity regime, the "graceful" exit from inflation to the standard radiation phase, as well as, the coincidence and cosmological constant problems. We show here that a simple running vacuum model or a time-dependent vacuum may provide insight to some of the above open questions (including a complete cosmic history), and also can explain the observed matter-antimatter asymmetry just after the initial deflationary period.

    ↳ gr-qchep-phhep-thInt.J.Mod.Phys.D(2018)·1 citation

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