Tue·May 30, 2017Tuesday·May 30, 2017

1. 01*

   Probing the Pseudoscalar portal to Dark Matter via $\bar{b}bZ(\to \ell \ell )+E_T/$: From the LHC to the Galactic Centre Excess

   Patrick Tunney🇬🇧 · Jose Miguel No🇬🇧 · Malcolm Fairbairn🇬🇧

   We propose a new search for Dark Matter at the LHC, characteristic of scenarios beyond the Standard Model with a pseudoscalar portal between the visible and dark sectors. This search, leading to a $\bar{b}bZ(\to \ell \ell )+E_T/$ final state, reaches large regions of parameter space not probed by Dark Matter searches via multi-jet $+E_T/$, searches for new scalars and flavour bounds. We show that this search could be used to test the Dark Matter origin of the gamma ray Galactic Centre excess with LHC Run 2 data.

   hep-phPRD(2017)·59 citations
2. 02*

   Clockwork Dark Matter

   Daniele Teresi🇧🇪

   I give a pedagogical discussion of thermal dark matter (DM) within the clockwork mechanism. The clockwork mechanism, which is a natural way to generate small numbers starting from order-one couplings, allows to have a long-lived, but unstable, DM particle that nevertheless has O(1) couplings with electroweak- or TeV-scale states. Remarkably, DM decays on time scales much longer than the age of the Universe and has at the same time sizeable couplings with light states, which therefore allow to produce it thermally within the WIMP paradigm. These new particles with large couplings can be searched for at current or future colliders. I also briefly comment on how this setup can minimally emerge from the deconstruction of an extra dimension in flat spacetime.

   hep-ph9 citations
3. 03*

   Universal Landau Pole and Physics below the 100 TeV Scale

   Christopher D. Carone🇺🇸 · Shikha Chaurasia🇺🇸 · John C. Donahue🇺🇸

   We reconsider the possibility that all standard model gauge couplings blow up at a common scale in the ultraviolet. The simplest implementation of this idea assumes supersymmetry and the addition of a single vector-like generation of matter fields around the TeV scale. We provide an up-to-date numerical study of this scenario and show that either the scale of the additional matter or the scale of supersymmetry breaking falls below potentially relevant LHC bounds. We then consider minimal extensions of the extra matter sector that raise its scale above the reach of the LHC, to determine whether there are cases that might be probed at a 100 TeV collider. We also consider the possibility that the heavy matter sector involves new gauge groups constrained by the same ultraviolet boundary condition, which in some cases can provide an explanation for the multiplicity of heavy states. We comment on the relevance of this framework to theories with dark and visible sectors.

   hep-phPRD(2017)·1 citation
4. 04*

   Exploring the Quark Flavour Puzzle within the 3 Higgs Model

   Nuno Rosa Agostinho🇪🇸 · David Emmanuel-Costa🇵🇹 · J.I. Silva-Marcos🇵🇹

   We extend the standard model with two extra Higgs doublets. Making use of a symmetry principle, we present flavour symmetries based on cycle groups $Z_N$ that oblige each Higgs doublet to contribute to the mass of only one generation, thus accommodating the quark mass hierarchy. We systematically search for all charge configurations that naturally lead to the alignment in flavour space of the quark sectors, resulting in a CKM matrix near to the identity, determined by the quark mass hierarchy, and with the correct overall phenomenological features. The minimal realisation is by the group $Z_7$. We show that only a limited number of solutions exist, and that any accidental global symmetry that may occur together with the discrete symmetry is necessarily anomalous. A phenomenological study of each class of solutions concerning predictions to the flavour changing neutral current (FCNC) phenomena is also performed: for some solutions, it is possible to obtain realistic quark masses and mixing, while the flavour violating neutral Higgs are sufficient lighter to be accessible at LHC.

   hep-phPRD(2017)·7 citations
5. 05*

   Directional Detection of Dark Matter using Spectroscopy of Crystal Defects

   Surjeet Rajendran🇺🇸 · Nicholas Zobrist🇺🇸 · Alexander O. Sushkov🇺🇸 · Ronald Walsworth🇺🇸 · Mikhail Lukin🇺🇸

   We propose a method to identify the direction of an incident Weakly Interacting Massive Particle (WIMP) via induced nuclear recoil. Our method is based on spectroscopic interrogation of quantum defects in macroscopic solid-state crystals . When a WIMP scatters in a crystal, the induced nuclear recoil creates a tell-tale damage cluster, localized to within about 50 nm, with an orientation to the damage trail that correlates well with the direction of the recoil and hence the incoming WIMP. This damage cluster induces strain in the crystal, shifting the energy levels of nearby quantum defects. These level shifts can be measured optically (or through paramagnetic resonance) making it possible to detect the strain environment around the defect in a solid sample. As a specific example, we consider nitrogen vacancy centers in diamond, for which high defect densities and nanoscale localization of individual defects have been demonstrated. To localize the millimeter-scale region of a nuclear recoil within the crystal due to a potential dark matter event, we can use conventional WIMP detection techniques such as the collection of ionization/scintillation. Once an event is identified, the quantum defects in the vicinity of the event can be interrogated to map the strain environment, thus determining the direction of the recoil. In principle, this approach should be able to identify the recoil direction with an efficiency greater than 70% at a false positive rate less than 5% for 10 keV recoil energies. If successful, this method would allow for directional detection of WIMP-induced nuclear recoils at solid state densities, enabling probes of WIMP parameter space below the solar neutrino floor. This technique could also potentially be applied to identify the direction of particles such as neutrons whose low scattering cross-section requires detectors with a large target mass.

   hep-phquant-phPRD(2017)·88 citations
6. 06*

   Quark mass function in Minkowski space

   Hidekazu Tanaka🇯🇵 · Shuji Sasagawa🇯🇵

   We investigate the properties of quark mass functions in quantum chromodynamics calculated by the Schwinger-Dyson equation in the strong coupling region, in which the loop integration is performed in Minkowski space. The calculated results are compared with those obtained by integration in Euclidean space.

   hep-phPTEP(2017)·5 citations
7. 07*

   Charmless Two-Body B Meson Decays In Factorization Assisted Topological Amplitude Approach

   Cai-Dian Lu🇨🇳 · Si-Hong Zhou🇨🇳

   We analyze charmless two-body non-leptonic $B$ decays under the framework of factorization assisted topological amplitude approach. Unlike the conventional flavor diagram approach, we consider flavor $SU(3)$ breaking effect assisted by factorization hypothesis for topological diagram amplitudes of different decay modes, by factorizing out the corresponding decay constants and form factors. The non-perturbative parameters of topology diagram magnitudes $\chi$ and strong phase $\varphi$ are universal that can be extracted by ${\chi }^2$ fit from current abundant experimental data of charmless $B$ decays. The number of free parameters and the ${\chi }^2$ per degree of freedom are both reduced comparing with previous analysis. With these best fitted parameters, we predict branching fractions and $CP$ asymmetry parameters of nearly 100 $B_{u,d}$ and $B_s$ decay modes. The long-standing $\pi \pi$ and $\pi K$-$CP$ puzzles are solved simultaneously.

   hep-ph0 citations
8. 08*

   Bulk viscosity of two-flavor quark matter from the Kubo formalism

   Arus Harutyunyan (ITP, Frankfurt)🇩🇪 · Armen Sedrakian (FIAS)🇩🇪

   We study the bulk viscosity of quark matter in the strong coupling regime within the two-flavor Nambu--Jona-Lasinio model. The dispersive effects that lead to non-zero bulk viscosity arise from quark-meson fluctuations above the Mott transition temperature, where meson decay into two quarks is kinematically allowed. We adopt the Kubo-Zubarev formalism and compute the equilibrium imaginary-time correlation function for pressure in the $O(1/N_c)$ power counting scheme. The bulk viscosity of matter is expressed in terms of the Lorentz components of the quark spectral function and includes multi-loop contributions which arise via re-summation of infinite geometrical series of loop diagrams. We show that the multi-loop contributions dominate the single-loop contribution close to the Mott line, whereas at high temperatures the one-loop contribution is dominant. The multi-loop bulk viscosity dominates the shear viscosity close to the Mott temperature by factors 5 to 20, but with increasing temperature the shear viscosity becomes the dominant dissipation mechanism of stresses as the one-loop contribution becomes the main source of bulk viscosity.

   hep-phastro-ph.HEastro-ph.SRnucl-thPRD(2017)·13 citations
9. 09*

   Four-fermion interactions and the chiral symmetry breaking in an external magnetic field

   Wei-jie Fu🇨🇳 · Yu-xin Liu🇨🇳

   We investigate the chiral symmetry and its spontaneous breaking at finite temperature and in an external magnetic field with four-fermion interactions of different channels. Quantum and thermal fluctuations are included within the functional renormalization group approach, and properties of the set of flow equations for different couplings, such as its fixed points, are discussed. It is found that external parameters, e.g. the temperature and the external magnetic field and so on, do not change the structure of the renormalization group flows for the couplings. The flow strength is found to be significantly dependent on the route and direction in the plane of couplings of different channels. Therefore, the critical temperature for the chiral phase transition shows a pronounced dependence on the direction as well. Given fixed initial ultraviolet couplings, the critical temperature increases with the increasing magnetic field, viz., the magnetic catalysis is observed with initial couplings fixed.

   hep-phPRD(2017)·16 citations
10. 10*

    Nuclear dependence of $R=\frac{{\sigma }_L}{{\sigma }_T}$ and Callan-Gross relation in nuclei

    F. Zaidi🇮🇳 · H. Haider🇮🇳 · M. Sajjad Athar🇮🇳 · S. K. Singh🇮🇳 · I. Ruiz Simo🇪🇸

    The electromagnetic nuclear structure functions $F_{1A}(x,Q^2)$, $F_{2A}(x,Q^2)$ and $F_{LA}(x,Q^2)$ have been calculated using a microscopic model of nucleus to study the nuclear medium effects on the ratio $R_A(x,Q^2)=\frac{{\sigma }_{LA}(x,Q^2)}{{\sigma }_{TA}(x,Q^2)}=\frac{F_{LA}(x,Q^2)}{2x{F}_{1A}(x,Q^2)}$ and the Callan-Gross relation(CGR) in nuclei. The nuclear medium effects due to the Fermi motion, binding energy, nucleon correlations, mesonic contribution and shadowing have been taken into account. The theoretical results for the nuclear dependence of $R_A(x,Q^2)$ and its impact on CGR have been presented and compared with the available experimental data on the various nuclear targets. The predictions have been made for $R_A(x,Q^2)$ in the kinematic region of $x$ and $Q^2$ for some nuclei relevant for the future experiments to be performed at the JLab.

    hep-phnucl-th3 citations
11. 11*

    Dual meson condensates in the Polyakov-loop extended linear sigma model

    Zhao Zhang🇨🇳 · Haipeng Lu🇨🇳

    Dual meson condensates as possible order parameters for deconfinement are investigated in a Polyakov-loop enhanced linear sigma model of QCD at both zero and finite isospin chemical potential ${\mu }_I$. We find that the rapid rise of the dual sigma condensate (corresponding to the dressed Polyakov-loop) with $T$ is driven by the chiral transition, no matter whether the Polyakov-loop dynamics is included or not. For ${\mu }_I>m_{\pi }/2$, the dual sigma condensate shows abnormal thermal behavior which even decreases with $T$ below the melting temperature $T_c^{I_3}$ of pion superfluidity; On the other hand, even the dual pion condensate always increases with $T$, its maximum slope locates exactly at $T_c^{I_3}$ rather than the deconfinement temperature $T_c^P$ determined by the Polyakov-loop. All these are qualitatively consistent with the previous results obtained in the Nambu-Jona-Lasinio type models. The dual vector meson condensate for ${\mu }_I>m_{\pi }/2$ is also calculated. This quantity is more sensitive to the chiral transition when taking into account the Dirac-sea contribution. Our study further suggests that it should be cautious to use dual observables to indicate the deconfinement transition, especially in QCD models.

    hep-phPRD(2021)·4 citations
12. 12*

    Where have all the large Representations gone?

    J. Lorenzo Diaz-Cruz🇲🇽

    Gauge theories describe the interactions of the fundamental building blocks of nature with great success. The Standard Model achieves a partial unification of the electromagnetic and weak interactions, and it also acomodates the strong interactions. The known quarks and leptons appear in the fundamental representations (or singlets) of the SU(3)_cxSU(2)_L x U(1)_Y gauge symmetry. However, larger representations (EW triplets, color sextes, etc.) could also occur in principle. Bounds on such exotic states based on electroweak precision tests, unitarity, perturbativity and collider searches, indicate that they should be very heavy or may be non-existent. But why only small representations occur in nature? Several ideas that could give some light into this problem are discussed here, including the approach of Nielsen et al, as well as the possible compositeness of quarks and leptons. Then, we discuss the problem within the context of grand unified theories, where a principle of "minimal complexity" is proposed to restrict the size of large representations, when they are required to form unified multiplets.

    hep-ph0 citations
13. 13*

    Open-flavor charmed/bottom $sq\bar{q}\bar{Q}$ and $qq\bar{q}\bar{Q}$ tetraquark states

    Wei Chen🇨🇦 · Hua-Xing Chen🇨🇳 · Xiang Liu🇨🇳 · T. G. Steele🇨🇦 · Shi-Lin Zhu🇨🇳

    We provide comprehensive investigations for the mass spectrum of exotic open-flavor charmed/bottom $sq\bar{q}\bar{c}$, $qq\bar{q}\bar{c}$, $sq\bar{q}\bar{b}$, $qq\bar{q}\bar{b}$ tetraquark states with various spin-parity assignments $J^P=0^{+},1^{+},2^{+}$ and $0^{-},1^{-}$ in the framework of QCD sum rules. In the diquark configuration, we construct the diquark-antidiquark interpolating tetraquark currents using the color-antisymmetric scalar and axial-vector diquark fields. The stable mass sum rules are established in reasonable parameter working ranges, which are used to give reliable mass predictions for these tetraquark states. We obtain the mass spectra for the open-flavor charmed/bottom $sq\bar{q}\bar{c}$, $qq\bar{q}\bar{c}$, $sq\bar{q}\bar{b}$, $qq\bar{q}\bar{b}$ tetraquark states with various spin-parity quantum numbers. In addition, we suggest searching for exotic doubly-charged tetraquarks, such as $[sd][\bar{u}\bar{c}]\to D_s^{(\ast )-}{\pi }^{-}$ in future experiments at facilities such as BESIII, BelleII, PANDA, LHCb and CMS, etc.

    hep-phPRD(2017)·42 citations
14. 14*

    Particle production in proton-nucleus collisions beyond leading order

    E. Iancu🇫🇷 · A.H. Mueller🇺🇸 · D.N. Triantafyllopoulos🇮🇹

    We describe the origin of, and the solution to, the negativity problem which occurs in the perturbative calculation of the cross-section for single-inclusive particle production in proton-nucleus collisions at next-to-leading-order.

    hep-phnucl-thNPA(2017)·0 citations
15. 15*

    Comment on "Disassembling the Clockwork Mechanism"

    Gian F. Giudice🇨🇭 · Matthew McCullough🇨🇭

    We respond to the criticism raised in the paper arXiv:1704.07831.

    hep-phhep-th49 citations
16. 16*

    $\mathcal{O}({\alpha }^3{\alpha }_s)$ Study on the yields and polarizations of $J/\psi ({\rm Y})$ within the framework of non-relativistic QCD via $\gamma \gamma \to J/\psi ({\rm Y})+\gamma +X$ at CEPC

    Zhan Sun🇨🇳 · Xiong Deng🇨🇳 · Hai Bing Fu🇨🇳

    Within the framework of the non-relativistic QCD (NRQCD), we make a systematical study of the yields and polarizations of $J/\psi$ and ${\rm Y}$ via $\gamma \gamma \to J/\psi ({\rm Y})+\gamma +X$ in photon-photon collisions at the Circular Electron Positron Collider (CEPC), up to $\mathcal{O}({\alpha }^3{\alpha }_s)$. We find that this process at CEPC is quite "clean", namely the direct photoproduction absolutely dominate over the single- and double- resolved processes, at least 2 orders of magnitude larger. It is found that the next-to-leading order (NLO) QCD corrections will significantly reduce the results due to that the virtual corrections to ${}^3{S}_1^1$ is large and negative. For $J/\psi$, as $p_t$ increases, the color octet (CO) processes will provide increasingly important contributions to the total NLO results. Moreover the inclusion of CO contributions will dramatically change the polarizations of $J/\psi$ from toally transverse to longitudinal, which can be regarded as a distinct signal for the CO mechanism. However, for the case of ${\rm Y}$, the effects of the CO processes are negligible, both for yields and polarizations. For $J/\psi$, the dependence of the yields on the value of the renormalization scale ${\mu }_r$ is moderate, while significant for the polarization. The impact of the variation of ${\mu }_{\lambda }$ is found to be relatively slight. As for the case of ${\rm Y}$, the uncertainties of ${\mu }_r$ and ${\mu }_{\lambda }$ just bring about negligible effects. The future measurements on this semi-inclusive photoproductions of $J/\psi ({\rm Y})+\gamma +X$, especially on the polarization parameters of $J/\psi$, will be a good laboratory for the study of heavy quarkonium production mechanism and helpful to clarify the problems of the $J/\psi$ polarization puzzle.

    hep-ph0 citations
17. 17*

    Precise predictions for dijet production at the LHC

    James Currie🇬🇧 · Aude Gehrmann-De Ridder🇨🇭 · Thomas Gehrmann🇨🇭 · E.W.N. Glover🇬🇧 · Alexander Huss🇨🇭 · Joao Pires🇩🇪

    We present the calculation of dijet production, doubly-differential in dijet mass, $m_{jj}$ and rapidity difference, $|y^{\ast }|$, at leading colour in all partonic channels at next-to-next-to-leading order (NNLO) in perturbative QCD. We consider the long-standing problems associated with scale choice for dijet production at next-to-leading order (NLO) and investigate the impact of including the NNLO contribution. We find that the NNLO theory provides reliable predictions, even when using scale choices which display pathological behaviour at NLO. We choose the dijet invariant mass as the theoretical scale on the grounds of perturbative convergence and residual scale variation and compare the predictions to the ATLAS 7 TeV 4.5 fb${}^{-1}$ data.

    hep-phhep-exPRL(2017)·158 citations
18. 18*

    Associated production of a Higgs boson decaying into bottom quarks at the LHC in full NNLO QCD

    Giancarlo Ferrera🇮🇹 · Gábor Somogyi🇭🇺 · Francesco Tramontano🇮🇹

    We consider the production of a Standard Model Higgs boson decaying to bottom quarks in association with a vector boson W/Z in hadron collisions. We present a fully exclusive calculation of QCD radiative corrections both for the production cross section and for the Higgs boson decay rate up to next-to-next-to-leading order (NNLO) accuracy. Our calculation also includes the leptonic decay of the vector boson with finite-width effects and spin correlations. We consider typical kinematical cuts applied in the experimental analyses at the Large Hadron Collider (LHC) and we find that the full NNLO QCD corrections significantly decrease the accepted cross section and have a substantial impact on the shape of distributions. We point out that these additional effects are essential to obtain precise theoretical predictions to be compared with the LHC data.

    hep-phPLB(2018)·89 citations
19. 19*

    Quantum Forces from Dark Matter and Where to Find Them

    Sylvain Fichet🇧🇷

    We observe that sub-GeV Dark Matter (DM) induces Casimir-Polder forces between nucleons, that can be accessed by experiments from nuclear to molecular scales. We calculate the nucleon-nucleon potentials arising in the DM effective theory and note that their main features are fixed by dimensional analysis and the optical theorem. Molecular spectroscopy and neutron scattering turn out be DM search experiments, and are found to be complementary to nucleon-based DM direct detection. Existing data set limits on DM with mass up to $\sim 3-50$ MeV and with effective interaction up to the $O(10-100)$ MeV scale, constraining a region typically difficult to reach for other experiments.

    hep-phPRL(2018)·82 citations
20. 20*

    Exploring GeV-scale Majorana neutrinos in lepton-number-violating ${\Lambda }_b^0$ baryon decays

    Jhovanny Mejia-Guisao🇲🇽 · Diego Milanes🇨🇴 · Nestor Quintero🇨🇴 · Jose D. Ruiz-Alvarez🇨🇴

    In this work, the lepton-number-violating processes in $|\Delta L|=2$ decays of ${\Lambda }_b^0$ baryon, ${\Lambda }_b^0\to p{\pi }^{+}{\mu }^{-}{\mu }^{-}$ and ${\Lambda }_b^0\to {\Lambda }_c^{+}{\pi }^{+}{\mu }^{-}{\mu }^{-}$, are investigated for the first time, via an intermediate on-shell Majorana neutrino $N$ with a mass in the GeV scale. We explore the experimental sensitivity of these dimuon channels at the LHCb and CMS experiments, in which heavy neutrino lifetimes in the accessible ranges of ${\tau }_N=[1,100,1000]$ ps are considered. For a integrated luminosity collected of 10 and 50 fb${}^{-1}$ at the LHCb and 30, 300 and 3000 fb${}^{-1}$ at the CMS, we found significant sensitivity on branching fractions of the order $\mathrm{BR}({\Lambda }_b^0\to p{\pi }^{+}{\mu }^{-}{\mu }^{-})\lesssim \mathcal{O}(10^{-9}-10^{-8})$ and $\mathrm{BR}({\Lambda }_b^0\to {\Lambda }_c^{+}{\pi }^{+}{\mu }^{-}{\mu }^{-})\lesssim \mathcal{O}(10^{-8}-10^{-7})$. Exclusion regions on the parameter space ($m_N,|V_{\mu N}{|}^2$) associated with the heavy neutrino are presented and compared with those from $K^{-}\to {\pi }^{+}{\mu }^{-}{\mu }^{-}$ (NA48/2) and $B^{-}\to {\pi }^{+}{\mu }^{-}{\mu }^{-}$ (LHCb) as well as by different search strategies such as NA3, CHARMII, NuTeV, Belle, and DELPHI.

    hep-phPRD(2017)·21 citations
21. 21*

    The nuclear configurational entropy impact parameter dependence in the Color-Glass Condensate

    Gayane Karapetyan🇧🇷

    The impact parameter (b) dependence on the saturation scale, in the framework of the Color Glass Condensate (b-CGC) dipole model, is investigated from the configurational point of view. During the calculations and analysis of the quantum nuclear states, the critical points of stability in the configurational entropy setup are computed, matching the experimental parameters that define the onset of the quantum regime in the b-CGC in the literature with very good accuracy. This new approach is crucial and important for understanding the stability of quantum systems in study of deep inelastic scattering processes.

    hep-phnucl-thEPL(2017)·38 citations
22. 22*

    Constraining Dwarf Spheroidal Dark Matter Halos With The Galactic Center Excess

    Jeremie Choquette🇨🇦

    If the gamma-ray excess from the galactic center reported by Fermi-LAT is a signal from annihilating dark matter, one must question why a similar excess has not been observed in dwarf spheroidal galaxies. We use this observation to place constraints on the density profile of dwarf spheroidal galaxies under the assumption that the galactic center excess is in fact a signal from annihilating dark matter. We place constraints on the generalized NFW parameter $\gamma$ and the Einasto profile parameter $\alpha$ which control the logarithmic slope of the inner regions of the halo's density profile. We determine that under these assumptions the galactic center excess is inconsistent with the standard NFW profile (and other `cuspy' profiles) for dwarf spheroidal galaxies , but is consistent with observations of cored dwarf galaxy profiles. Specifically, we find that dwarf spheroidal profiles must be less cuspy than that of the Milky Way. Models of dark matter which self-interacts through a light mediator can achieve this.

    ↳ astro-ph.COastro-ph.HEhep-phPRD(2018)·5 citations
23. 23*

    Supersymmetry in a dynamical M-brane background

    Kengo Maeda🇯🇵 · Kunihito Uzawa🇯🇵

    The supersymmetry arises in certain theories of fermions coupled to gauge fields and gravity in a spacetime of 11 dimensions. The dynamical brane background has mainly been studied for the class of purely bosonic solutions only, but recent developments involving a time-dependent brane solution have made it clear that one can get more information by asking what happens on supersymmetric systems. In this paper, we construct an exact supersymmetric solution of a dynamical M-brane background in the 11-dimensional supergravity and investigate supersymmetry breaking, the geometric features near the singularity and the black hole horizon.

    ↳ hep-thgr-qchep-phPRD(2017)·3 citations
24. 24*

    Observational Constraints on the Primordial Curvature Power Spectrum

    Razieh Emami (Hong Kong U. Sci. Tech)🇨🇳 · George Smoot (Hong Kong U. Sci. Tech. and APC, Paris and LBL, Berkeley and Paris Cent. Cosmol. Phys.)🇨🇳

    CMB observations provide a precise measurement of the primordial power spectrum on large scales, corresponding to wavenumbers $10^{-3}$ Mpc${}^{-1}$ < k < 0.1 Mpc${}^{-1}$, [1-8]. Luminous red galaxies and galaxy clusters probe the matter power spectrum on overlapping scales (0.02 Mpc${}^{-1}$ < k < 0.7 Mpc${}^{-1}$ [9-18]), while the Lyman-alpha forest reaches slightly smaller scales (0.3 Mpc${}^{-1}<k<3$ Mpc${}^{-1}$; [19]). These observations indicate that the primordial power spectrum is nearly scale-invariant with amplitude close to $2\times 10^{-9}$, [5, 20-25]. They also strongly support Inflation and motivate us to obtain constraints reaching to smaller scales on the primordial curvature power spectrum and by implication on Inflation. One could obtain limits to much higher values of $k<10^5$ Mpc${}^{-1}$ and with less sensitivity even higher to $k<10^{19}-10^{23}$ Mpc${}^{-1}$ using limits from CMB spectral distortions(SD)and on ultracompact minihalo objects(UCMHs)and Primordial Black Holes(PBHs). In this paper, we revisit and collect all the known constraints on both PBHs and UCMHs. We show that unless one uses SD, PBHs give us very relaxed bounds on the primordial curvature perturbations. UCMHs are very informative over a reasonable $k$ range($3<k<10^6$ Mpc${}^{-1}$)and lead to significant upper-bounds on the curvature spectrum. We review the conditions under which the tighter constraints on the UCMHs could imply extremely strong bounds on the fraction of Dark Matter that could be PBHs. Failure to satisfy these conditions would lead to over production of the UCMHs, which is inconsistent with the observations. Therefore, we can almost rule out PBH within their overlap scales with the UCMHs. We consider the UCMH bounds from experiments such as $\gamma$-rays, Neutrinos, Reionization, pulsar-timing and SD. We show that they lead to comparable results independent of the form of DM.

    ↳ astro-ph.COastro-ph.HEgr-qchep-ph+1JCAP(2018)·37 citations
25. 25*

    Chiral magnetic effect of light

    Tomoya Hayata🇯🇵

    We study a photonic analog of the chiral magnetic (vortical) effect. We discuss that the vector component of magnetoelectric tensors plays a role of "vector potential," and its rotation is understood as "magnetic field" of a light. Using the geometrical optics approximation, we show that "magnetic fields" cause an anomalous shift of a wave packet of a light through an interplay with the Berry curvature of photons. The mechanism is the same as that of the chiral magnetic (vortical) effect of a chiral fermion, so that we term the anomalous shift "chiral magnetic effect of a light." We further study the chiral magnetic effect of a light beyond geometric optics by directly solving the transmission problem of a wave packet at a surface of a magnetoelectric material. We show that the experimental signal of the chiral magnetic effect of a light is the nonvanishing of transverse displacements for the beam normally incident to a magnetoelectric material.

    ↳ physics.opticscond-mat.mes-hallhep-phhep-thPRB(2018)·6 citations
26. 26*

    Thermal Sunyaev-Zel'dovich effect in the intergalactic medium with primordial magnetic fields

    Teppei Minoda🇯🇵 · Kenji Hasegawa🇯🇵 · Hiroyuki Tashiro🇯🇵 · Kiyotomo Ichiki🇯🇵 · Naoshi Sugiyama🇯🇵

    The presence of ubiquitous magnetic fields in the universe is suggested from observations of radiation and cosmic ray from galaxies or the intergalactic medium (IGM). One possible origin of cosmic magnetic fields is the magnetogenesis in the primordial universe. Such magnetic fields are called primordial magnetic fields (PMFs), and are considered to affect the evolution of matter density fluctuations and the thermal history of the IGM gas. Hence the information of PMFs is expected to be imprinted on the anisotropies of the cosmic microwave background (CMB) through the thermal Sunyaev-Zel'dovich (tSZ) effect in the IGM. In this study, given an initial power spectrum of PMFs as $P(k)\propto B_{1Mpc}^2{k}^{n_B}$, we calculate dynamical and thermal evolutions of the IGM under the influence of PMFs, and compute the resultant angular power spectrum of the Compton $y$-parameter on the sky. As a result, we find that two physical processes driven by PMFs dominantly determine the power spectrum of the Compton $y$-parameter; (i) the heating due to the ambipolar diffusion effectively works to increase the temperature and the ionization fraction, and (ii) the Lorentz force drastically enhances the density contrast just after the recombination epoch. These facts result in making the tSZ angular power spectrum induced by the PMFs more remarkable at $\ell >10^4$ than that by galaxy clusters even with $B_{1Mpc}=0.1$ nG and $n_B=-1.0$ because the contribution from galaxy clusters decreases with increasing $\ell$. The measurement of the tSZ angular power spectrum on high $\ell$ modes can provide the stringent constraint on PMFs.

    ↳ astro-ph.COastro-ph.GAhep-phPRD(2017)·20 citations
27. 27*

    Gluo-dissociation of Heavy Quarkonium in the Quark-Gluon Plasma Revisited

    Shile Chen🇨🇳 · Min He🇨🇳

    Using an effective Hamiltonian derived from the QCD multipole expansion, we calculate the cross sections of gluo-dissociation of heavy quarkonia in the quark-gluon plasma, by including both the chromo-electric dipole ($E_1$) as well as the chromo-magnetic dipole ($M_1$) transition mechanisms. While the former allows to reproduce the results from operator-product-expansion calculations in the Coulomb approximation, the latter as a novel contribution is shown to be significant at low energies close to the threshold. Using thus obtained cross sections, we further carry out a full calculation of the gluo-dissociation rates for various charmonia and bottomonia within a non-relativitic in-medium potential model. The $M_1$ contribution turns out to be most prominent for the $J/\psi$ and accounts for $\sim 10\%-25\%$ of the total ($E1+M1$) dissociation rate at temperatures close to the transition temperature.

    ↳ nucl-thhep-phPRC(2017)·19 citations
28. 28*

    The analytic structure and the transcendental weight of the BFKL ladder at NLL accuracy

    Vittorio Del Duca🇨🇭 · Claude Duhr🇨🇭 · Robin Marzucca🇧🇪 · Bram Verbeek🇧🇪

    We study some analytic properties of the BFKL ladder at next-to-leading logarithmic accuracy (NLLA). We use a procedure by Chirilli and Kovchegov to construct the NLO eigenfunctions, and we show that the BFKL ladder can be evaluated order by order in the coupling in terms of certain generalised single-valued multiple polylogarithms recently introduced by Schnetz. We develop techniques to evaluate the BFKL ladder at any loop order, and we present explicit results up to five loops. Using the freedom in defining the matter content of the NLO BFKL eigenvalue, we obtain conditions for the BFKL ladder in momentum space at NLLA to have maximal transcendental weight. We observe that, unlike in moment space, the result in momentum space in N = 4 SYM is not identical to the maximal weight part of QCD, and moreover that there is no gauge theory with this property. We classify the theories for which the BFKL ladder at NLLA has maximal weight in terms of their field content, and we find that these theories are highly constrained: there are precisely four classes of theories with this property involving only fundamental and adjoint matter, all of which have a vanishing one-loop beta function and a matter content that fits into supersymmetric multiplets. Our findings indicate that theories which have maximal weight are highly constrained and point to the possibility that there is a connection between maximal transcendental weight and superconformal symmetry.

    ↳ hep-thhep-phJHEP(2017)·31 citations
29. 29*

    Landau levels in QCD

    F. Bruckmann🇩🇪 · G. Endrodi🇩🇪 · M. Giordano🇭🇺 · S. D. Katz🇭🇺 · T. G. Kovacs🇭🇺 · F. Pittler🇭🇺 · J. Wellnhofer🇩🇪

    We present first evidence for the Landau level structure of Dirac eigenmodes in full QCD for nonzero background magnetic fields, based on first principles lattice simulations using staggered quarks. Our approach involves the identification of the lowest Landau level modes in two dimensions, where topological arguments ensure a clear separation of these modes from energetically higher states, and an expansion of the full four-dimensional modes in the basis of these two-dimensional states. We evaluate various fermionic observables including the quark condensate and the spin polarization in this basis to find how much the lowest Landau level contributes to them. The results allow for a deeper insight into the dynamics of quarks and gluons in background magnetic fields and may be directly compared to low-energy models of QCD employing the lowest Landau level approximation.

    ↳ hep-lathep-phhep-thnucl-thPRD(2017)·61 citations
30. 30*

    Second moment of the pion distribution amplitude with the momentum smearing technique

    RQCD Collaboration: G. S. Bali (1 and 2)🇩🇪 · V. M. Braun (1)🇩🇪 · M. Göckeler (1)🇩🇪 · M. Gruber (1)🇩🇪 · F. Hutzler (1)🇩🇪 · P. Korcyl (1 and 3)🇩🇪 · B. Lang (1)🇩🇪 · A. Schäfer (1) ((1) Universität Regensburg, (2) Tata Institute of Fundamental Research, (3) Jagiellonian University)🇩🇪

    Using the second moment of the pion distribution amplitude as an example, we investigate whether lattice calculations of matrix elements of local operators involving covariant derivatives may benefit from the recently proposed momentum smearing technique for hadronic interpolators. Comparing the momentum smearing technique to the traditional Wuppertal smearing we find - at equal computational cost - a considerable reduction of the statistical errors. The present investigation was carried out using $N_f=2+1$ dynamical non-perturbatively order $a$ improved Wilson fermions on lattices of different volumes and pion masses down to 220 MeV.

    ↳ hep-lathep-phPLB(2017)·42 citations
31. 31*

    Pentaquark states with hidden charm

    Roelof Bijker🇲🇽

    I develop an extension of the usual three-flavor quark model to four flavors (u, d, s and c), and discuss the classification of pentaquark states with hidden charm. This work is motivated by the recent observation of such states by the LHCb Collatoration at CERN.

    ↳ nucl-thhep-exhep-phnucl-exJ.Phys.Conf.Ser.(2017)·1 citation
32. 32*

    The decay width of stringy hadrons

    Jacob Sonnenschein🇮🇱 · Dorin Weissman🇮🇱

    In this paper we further develop a string model of hadrons by computing their strong decay widths and comparing them to experiment. The main decay mechanism is that of a string splitting into two strings. The corresponding total decay width behaves as $\Gamma =\frac{\pi }{2}ATL$ where $T$ and $L$ are the tension and length of the string and $A$ is a dimensionless universal constant. We show that this result holds for a bosonic string not only in the critical dimension. The partial width of a given decay mode is given by ${\Gamma }_i/\Gamma ={\Phi }_i\exp (-2\pi C{m}_{sep}^2/T)$ where ${\Phi }_i$ is a phase space factor, $m_{sep}$ is the mass of the "quark" and "antiquark" created at the splitting point, and $C$ is a dimensionless coefficient close to unity. Based on the spectra of hadrons we observe that their (modified) Regge trajectories are characterized by a negative intercept. This implies a repulsive Casimir force that gives the string a "zero point length". We fit the theoretical decay width to experimental data for mesons on the trajectories of $\rho$, $\omega$, $\pi$, $\eta$, $K^{\ast }$, $\varphi$, $D$, and $D_s^{\ast }$, and of the baryons $N$, $\Delta$, $\Lambda$, and $\Sigma$. We examine both the linearity in $L$ and the exponential suppression factor. The linearity was found to agree with the data well for mesons but less for baryons. The extracted coefficient for mesons $A=0.095\pm 0.015$ is indeed quite universal. The exponential suppression was applied to both strong and radiative decays. We discuss the relation with string fragmentation and jet formation. We extract the quark-diquark structure of baryons from their decays. A stringy mechanism for Zweig suppressed decays of quarkonia is proposed and is shown to reproduce the decay width of ${\rm Y}$ states. The dependence of the width on spin and flavor symmetry is discussed. We further apply this model to the decays of glueballs and exotic hadrons.

    ↳ hep-thhep-exhep-lathep-phNPB(2018)·17 citations
33. 33*

    Effective potential of the three-dimensional Ising model: the pseudo-$ϵ$ expansion study

    A.I.Sokolov🇷🇺 · A.Kudlis🇷🇺 · M.A.Nikitina🇷🇺

    The ratios $R_{2k}$ of renormalized coupling constants $g_{2k}$ that enter the effective potential and small-field equation of state acquire the universal values at criticality. They are calculated for the three-dimensional scalar $\lambda {\varphi }^4$ field theory (3D Ising model) within the pseudo-$ϵ$ expansion approach. Pseudo-$ϵ$ expansions for the critical values of $g_6$, $g_8$, $g_{10}$, $R_6=g_6/g_4^2$, $R_8=g_8/g_4^3$ and $R_{10}=g_{10}/g_4^4$ originating from the five-loop renormalization group (RG) series are derived. Pseudo-$ϵ$ expansions for the sextic coupling have rapidly diminishing coefficients, so addressing Padé approximants yields proper numerical results. Use of Padé--Borel--Leroy and conformal mapping resummation techniques further improves the accuracy leading to the values $R_6^{\ast }=1.6488$ and $R_6^{\ast }=1.6490$ which are in a brilliant agreement with the result of advanced lattice calculations. For the octic coupling the numerical structure of the pseudo-$ϵ$ expansions is less favorable. Nevertheless, the conform-Borel resummation gives $R_8^{\ast }=0.868$, the number being close to the lattice estimate $R_8^{\ast }=0.871$ and compatible with the result of 3D RG analysis $R_8^{\ast }=0.857$. Pseudo-$ϵ$ expansions for $R_{10}^{\ast }$ and $g_{10}^{\ast }$ are also found to have much smaller coefficients than those of the original RG series. They remain, however, fast growing and big enough to prevent obtaining fair numerical estimates.

    ↳ cond-mat.stat-mechhep-lathep-phhep-thNPB(2017)·4 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.