Thu·Sep 7, 2017Thursday·September 7, 2017

1. 01*

   Enhancement of the Dark Matter Abundance Before Reheating: Applications to Gravitino Dark Matter

   Marcos A. G. Garcia🇺🇸 · Yann Mambrini🇫🇷 · Keith A. Olive🇺🇸 · Marco Peloso🇺🇸

   In the first stages of inflationary reheating, the temperature of the radiation produced by inflaton decays is typically higher than the commonly defined reheating temperature $T_{RH}\sim ({\Gamma }_{\varphi }{M}_P{)}^{1/2}$ where ${\Gamma }_{\varphi }$ is the inflaton decay rate. We consider the effect of particle production at temperatures at or near the maximum temperature attained during reheating. We show that the impact of this early production on the final particle abundance depends strongly on the temperature dependence of the production cross section. For $⟨\sigma v⟩\sim T^n/M^{n+2}$, and for $n<6$, any particle produced at $T_{\max }$ is diluted by the later generation of entropy near $T_{RH}$. This applies to cases such as gravitino production in low scale supersymmetric models ($n=0$) or NETDM models of dark matter ($n=2$). However, for $n\ge 6$ the net abundance of particles produced during reheating is enhanced by over an order of magnitude, dominating over the dilution effect. This applies, for instance to gravitino production in high scale supersymmetry models where $n=6$.

   hep-phastro-ph.COPRD(2017)·124 citations
2. 02*

   A First Step Towards Effectively Nonperturbative Scattering Amplitudes in the Perturbative Regime

   Neil Christensen🇺🇸 · Joshua Henderson🇺🇸 · Santiago Pinto🇺🇸 · Cory Russ🇺🇸

   We propose an effectively nonperturbative approach to calculating scattering amplitudes in the perturbative regime. We do this in a discretized momentum space by using the QSE method to calculate all the contributions (to all orders in perturbation theory) to the scattering eigenstates that are above a precision cutoff. We then calculate the scattering amplitude by directly taking the inner product between these eigenstates. In the current work we have analyzed this procedure for a $\lambda {\varphi }^4$ theory in one spatial dimension and compared our results with perturbation theory obtaining favorable results suggestive that further research in this direction might be worthwhile. In particular, we show that the efficiency of our method scales much better than second- and higher-order perturbation theory as the momentum lattice spacing decreases and as the eigenstate energy increases.

   hep-phJ.Phys.Comm.(2018)·0 citations
3. 03*

   Traveling Waves in the Euler-Heisenberg Electrodynamics

   A. Bermudez Manjarres🇨🇴 · Marek Nowakowski🇨🇴

   We examine the possibility of travelling wave solutions within the nonlinear Euler-Heisenberg electrodynamics. Since this theory resembles in its form the electrodynamics in matter, it is a priori not clear if there exist travelling wave solutions with a new dispersion relation for $\omega (k)$ or if the Euler-Heisenberg theory stringently imposes $\omega =k$ for any arbitrary ansatz $\mathbf{E}(\xi )$ and $\mathbf{B}(\xi )$ with $\xi \equiv \mathbf{k}\cdot \mathbf{r}-\omega t$. We show that the latter scheme applies for the Euler-Heisenberg theory, but point out the possibility of new solutions with $\omega \ne k$ if we go beyond the Euler-Heisenberg theory, allowing strong fields. In case of the Euler-Heisenberg theory the quantum mechanical effect of the travelling wave solutions remains in $\hslash$ corrections to the energy density and the Poynting vector.

   hep-phmath-phmath.MPPRA(2017)·6 citations
4. 04*

   Constraints on Mirror Models of Dark Matter from Observable Neutron-Mirror Neutron Oscillation

   Rabindra N. Mohapatra🇺🇸 · Shmuel Nussinov🇮🇱

   The process of neutron-mirror neutron oscillation, motivated by symmetric mirror dark matter models, is governed by two parameters: $n-n^{\prime }$ mixing parameter $\delta$ and $n-n^{\prime }$ mass splitting $\Delta$. For neutron mirror neutron oscillation to be observable, the splitting between their masses $\Delta$ must be small and current experiments lead to $\delta \le 2\times 10^{-27}$ GeV and$\Delta \le 10^{-24}$ GeV. We show that in mirror universe models where this process is observable, this small mass splitting constrains the way that one must implement asymmetric inflation to satisfy the limits of Big Bang Nucleosynthesis on the number of effective light degrees of freedom. In particular we find that if asymmetric inflation is implemented by inflaton decay to color or electroweak charged particles, the oscillation is unobservable. Also if one uses SM singlet fields for this purpose, they must be weakly coupled to the SM fields.

   hep-phPLB(2018)·26 citations
5. 05*

   Gluonic Distribution in the Constituent Quark and Nucleon Induced by the Instantons

   Baiyang Zhang🇨🇳 · Nikolai Kochelev🇷🇺 · Hee-Jung Lee🇰🇷 · Pengming Zhang🇨🇳

   Instanton effects can give large contribution to strong interacting processes, especially at the energy scale where perturbative QCD is no longer valid. However instanton contribution to the gluon contribution in constituent quark and nucleon has never been calculated before. Based on both the constituent quark picture and the instanton model for QCD vacuum, we calculate the unpolarized and polarized gluon distributions in the constituent quark and in the nucleon for the first time. We find that the pion field plays an important role in producing both the unpolarized and the polarized gluon distributions.

   hep-phPhys.Part.Nucl.Lett.(2018)·0 citations
6. 06*

   Unitarity Analyses of $\pi N$ Elastic Scattering Amplitudes

   Yu-Fei Wang🇨🇳

   The pion - nucleon scattering phase shifts in $s$ and $p$ waves are analyzed using PKU unitarization approach that can separate the phase shifts into different contributions from poles and branch cuts. It is found that in $S_{11}$ and $P_{11}$ channels, there exist large and positive missing contributions when one compares the phase shift from known resonances plus branch cuts with the experimental data, which indicates that those two channels may contain sizable effects from $N^{\ast }(1535)$ and $N^{\ast }(1440)$ shadow poles. Those results are obtained using tree level results of the $\pi N$ amplitude.

   hep-phnucl-thPhys.Part.Nucl.Lett.(2018)·0 citations
7. 07*

   Top Quark Rare Decays via Loop-Induced FCNC Interactions in Extended Mirror Fermion Model

   P. Q. Hung🇺🇸 · Yu-Xiang Lin🇹🇼 · Chrisna Setyo Nugroho🇹🇼 · Tzu-Chiang Yuan🇹🇼

   Flavor changing neutral current (FCNC) interactions for a top quark $t$ decays into $Xq$ with $X$ represents a neutral gauge or Higgs boson, and $q$ a up- or charm-quark are highly suppressed in the Standard Model (SM) due to the Glashow-Iliopoulos-Miami mechanism. Whilst current limits on the branching ratios of these processes have been established at the order of $10^{-4}$ from the Large Hadron Collider experiments, SM predictions are at least nine orders of magnitude below. In this work, we study some of these FCNC processes in the context of an extended mirror fermion model, originally proposed to implement the electroweak scale seesaw mechanism for non-sterile right-handed neutrinos. We show that one can probe the process $t\to Zc$ for a wide range of parameter space with branching ratios varying from $10^{-6}$ to $10^{-8}$, comparable with various new physics models including the general two Higgs doublet model with or without flavor violations at tree level, minimal supersymmetric standard model with or without $R$-parity, and extra dimension model.

   hep-phhep-exNPB(2018)·22 citations
8. 08*

   $A_4$ realization of Linear Seesaw and Neutrino Phenomenology

   M. Sruthilaya🇮🇳 · Rukmani Mohanta🇮🇳 · Sudhanwa Patra🇮🇳

   Motivated by the crucial role played by the discrete flavour symmetry groups in explaining the observed neutrino oscillation data, we consider the $A_4$ realization of linear seesaw by extending the standard model (SM) particle content with two types of right-handed neutrinos along with the flavon fields, and the SM symmetry with $A_4\times Z_4\times Z_2$ and a global symmetry $U(1{)}_X$ which is broken explicitly by the Higgs potential. We scrutinize whether this model can explain the recent results from neutrino oscillation experiments by searching for parameter space that can accommodate the observables such as the reactor mixing angle ${\theta }_{13}$, the CP violating phase ${\delta }_{CP}$, sum of active neutrino masses ${\Sigma }_i{m}_i$, solar and atmospheric mass squared differences, and the lepton number violating parameter called as effective Majorana mass parameter, in line with recent experimental results. We also discuss the scope of this model to explain the baryon asymmetry of the universe through Leptogenesis. We also investigate the possibility of probing the non-unitarity effect in this scenario, but it is found to be rather small.

   hep-phEPJC(2018)·31 citations
9. 09*

   Production and sequential decays of charmed hyperons

   Göran Fäldt🇸🇪

   We investigate production and decay of the ${\Lambda }_c^{+}$ hyperon. The production considered is through the $e^{+}{e}^{-}$ annihilation channel, $e^{+}{e}^{-}\to {\Lambda }_c^{+}{\bar{\Lambda }}_c^{-}$, with summation over the ${\bar{\Lambda }}_c^{-}$ anti-hyperon spin directions. It is in this situation that the ${\Lambda }_c^{+}$ decay chain is identified. Two kinds of sequential decays are studied. The first one is the doubly weak decay $B_1\to B_2{M}_2$, followed by $B_2\to B_3{M}_3$. The other one is the mixed weak-electromagnetic decay $B_1\to B_2{M}_2$, followed by $B_2\to B_3\gamma$. In both schemes $B$ denotes baryons and $M$ mesons. We should also mention that the initial state of the ${\Lambda }_c^{+}$ hyperon is polarized.

   hep-phPRD(2018)·16 citations
10. 10*

    Characterizing a benchmark scenario for heavy Higgs boson searches in the Georgi-Machacek model

    Heather E. Logan🇨🇦 · Mark B. Reimer (Carleton U.)🇨🇦

    The Georgi-Machacek model is used to motivate and interpret LHC searches for doubly- and singly-charged Higgs bosons decaying into vector boson pairs. In this paper we study the constraints on and phenomenology of the "H5plane" benchmark scenario in the Georgi-Machacek model, which has been proposed for use in these searches. We show that the entire H5plane benchmark is compatible with the LHC measurements of the 125 GeV Higgs boson couplings. We also point out that, over much of the H5plane benchmark, the lineshapes of the two CP-even neutral heavy Higgs bosons $H$ and $H_5^0$ will overlap and interfere when produced in vector boson fusion with decays to $W^{+}{W}^{-}$ or $ZZ$. Finally we compute the decay branching ratios of the additional heavy Higgs bosons within the H5plane benchmark to facilitate the development of search strategies for these additional particles.

    hep-phPRD(2017)·30 citations
11. 11*

    Charming Dark Matter

    Thomas Jubb🇬🇧 · Matthew Kirk🇬🇧 · Alexander Lenz🇬🇧

    We have considered a model of Dark Minimal Flavour Violation (DMFV), in which a triplet of dark matter particles couple to right-handed up-type quarks via a heavy colour-charged scalar mediator. By studying a large spectrum of possible constraints, and assessing the entire parameter space using a Markov Chain Monte Carlo (MCMC), we can place strong restrictions on the allowed parameter space for dark matter models of this type.

    hep-phJHEP(2017)·23 citations
12. 12*

    Constraining the parameter space of branon dark matter using white dwarf stars

    Grigoris Panotopoulos🇵🇹 · Ilidio Lopes🇵🇹

    In the present work we study the branon dark matter particles impact on compact objects, and we provide the first constraints of the parameter space using white dwarf stars. The branon dark matter model is characterized by two free parameters, namely the branon mass particle M and the brane tension factor $f$. The latter determines the strength of the interaction of branon dark matter particles with baryons. By considering a typical white dwarf star we were able to obtain constraints on branon dark matter and compare with current limits obtained by direct detection searches and dark matter abundance. In particular our results show that i) for heavy branons with a mass $M>10GeV$ white dwarfs fail to provide us with bounds better than current limits from DM direct detection searches, and ii) for light branons in the mass range $2keV<M<1GeV$, which cannot be probed neither with current dark matter experiments nor with the next generation of detectors, the dark matter abundance constrain determines $f$ as a function of $M$ in the range $0.1GeV<M<1GeV$ for the branon mass and $1GeV<f<5GeV$ for the brane tension factor. Furthermore, our findings indicate that the limits from white dwarfs are not stronger than the dark matter abundance constrain.

    hep-phPRD(2017)·4 citations
13. 13*

    Baryon magnetic moments: Symmetries and relations

    Assumpta Parreno🇪🇸 · Martin J. Savage🇺🇸 · Brian C. Tiburzi🇺🇸 · Jonas Wilhelm🇩🇪 · Emmanuel Chang🇺🇸 · William Detmold🇺🇸 · Kostas Orginos🇺🇸

    Magnetic moments of the octet baryons are computed using lattice QCD in background magnetic fields, including the first treatment of the magnetically coupled Sigma-Lambda system. Although the computations are performed for relatively large values of the up and down quark masses, we gain new insight into the symmetries and relations between magnetic moments by working at a three-flavor mass-symmetric point. While the spin-flavor symmetry in the large Nc limit of QCD is shared by the naive constituent quark model, we find instances where quark model predictions are considerably favored over those emerging in the large Nc limit. We suggest further calculations that would shed light on the curious patterns of baryon magnetic moments.

    ↳ hep-lathep-phnucl-thEPJ Web Conf.(2018)·3 citations
14. 14*

    Energy dependent forward B $\to$ $J/\psi$ measurements in p+p collisions at PHENIX

    Xuan Li (for the PHENIX Collaboration)🇺🇸

    The heavy flavor studies at RHIC help improve the knowledge of the bottom/charm quark production and can test Quantum Chromodynamics (QCD). Compared to the LHC/Tevatron, the RHIC heavy flavor production originates from different partonic sub-processes and has a complementary kinematic coverage. The PHENIX forward rapidity silicon vertex detector (FVTX) provides precise determination of the event vertex, tracking and the Distance of Closest Approach (DCA) of charged tracks. This detector allows direct access to the $B$ meson production via measurements of non-prompt $J/\psi \to {\mu }^{+}+{\mu }^{-}$ within $1.2<|y|<2.2$ rapidity in $p$+$p$ collisions at $\sqrt{s}=$ 510 and 200 GeV. Comparison among PHENIX measurements of the $B\to J/\psi$ fraction with integrated $J/\psi$ $p_T$ up to 5 GeV$/c$ and higher energy results at the Tevatron and the LHC presents a smooth center of mass energy dependence from 0.2 to 13 TeV in $p$+$p$ ($p$+$\bar{p}$) collisions. The Next-To-Leading order Perturbative QCD (NLO pQCD) calculations are in reasonable agreement with the extracted total $b\bar{b}$ cross section based on the $B\to J/\psi$ fraction measurements at PHENIX.

    ↳ nucl-exhep-exhep-phPoS(2018)·0 citations
15. 15*

    Electric fields at finite temperature

    A. Bermudez Manjarres🇨🇴 · N. G. Kelkar🇨🇴 · Marek Nowakowski🇨🇴

    Partial differential equations for the electric potential at finite temperature, taking into account the thermal Euler-Heisenberg contribution to the electromagnetic Lagrangian are derived. This complete temperature dependence introduces quantum corrections to several well known equations such as the Thomas-Fermi and the Poisson-Boltzmann equation. Our unified approach allows at the same time to derive other similar equations which take into account the effect of the surrounding heat bath on electric fields. We vary our approach by considering a neutral plasma as well as the screening caused by electrons only. The effects of changing the statistics from Fermi-Dirac to the Tsallis statistics and including the presence of a magnetic field are also investigated. Some useful applications of the above formalism are presented.

    ↳ nucl-thhep-phAnnals Phys.(2017)·5 citations
16. 16*

    Primordial gravitational waves amplification from causal fluids

    N. Miron Granese🇦🇷 · E. Calzetta🇦🇷

    We consider the evolution of the gravitational wave spectrum for super-Hubble modes in interaction with a relativistic fluid, which is regarded as an effective description of fluctuations in a light scalar minimally coupled field, during the earliest epoch of the radiation dominated era after the end of inflation. We obtain the initial conditions for gravitons and fluid from quantum fluctuations at the end of inflation, and assume instantaneous reheating. We model the fluid by using relativistic causal hydrodynamics. There are two dimensionful parameters, the relaxation time $\tau$ and temperature. In particular we study the interaction between gravitational waves and the non trivial tensor (spin 2) part of the fluid energy-momentum tensor. Our main result is that the new dimensionful parameter $\tau$ introduces a new relevant scale which distinguishes two kinds of super-Hubble modes. For modes with $H^{-1}<\lambda <\tau$ the fluid-graviton interaction increases the amplitude of the primordial gravitational wave spectrum at the electroweak transition by a factor of about $1.3$ with respect to the usual scale invariant spectrum.

    ↳ gr-qcastro-ph.COhep-phPRD(2018)·15 citations
17. 17*

    Scalar Fields, Hierarchical UV/IR Mixing and The Weak Gravity Conjecture

    Dieter Lust🇩🇪 · Eran Palti🇩🇪

    The Weak Gravity Conjecture (WGC) bounds the mass of a particle by its charge. It is expected that this bound can not be below the ultraviolet cut-off scale of the effective theory. Recently, an extension of the WGC was proposed in the presence of scalar fields. We show that this more general version can bound the mass of a particle to be arbitrarily far below the ultraviolet cut-off of the effective theory. It therefore manifests a form of hierarchical UV/IR mixing. This has possible implications for naturalness. We also present new evidence for the proposed contribution of scalar fields to the WGC by showing that it matches the results of dimensional reduction. In such a setup the UV/IR mixing is tied to the interaction between the WGC and non-local gauge operators.

    ↳ hep-thgr-qchep-phJHEP(2018)·84 citations
18. 18*

    Distribution law of the Dirac eigenmodes in QCD

    M. Catillo🇦🇹 · L. Ya. Glozman🇦🇹

    The near-zero modes of the Dirac operator are connected to spontaneous breaking of chiral symmetry in QCD (SBCS) via the Banks-Casher relation. At the same time the distribution of the near-zero modes is well described by the Random Matrix Theory (RMT) with the Gaussian Unitary Ensemble (GUE). Then it has become a standard lore that a randomness, as observed through distributions of the near-zero modes of the Dirac operator, is a consequence of SBCS. The higher-lying modes of the Dirac operator are not affected by SBCS and are sensitive to confinement physics and related $SU(2{)}_{CS}$ and $SU(2N_F)$ symmetries. We study the distribution of the near-zero and higher-lying eigenmodes of the overlap Dirac operator within $N_F=2$ dynamical simulations. We find that both the distributions of the near-zero and higher-lying modes are perfectly described by GUE of RMT. This means that randomness, while consistent with SBCS, is not a consequence of SBCS and is related to some more general property of QCD in confinement regime.

    ↳ hep-lathep-phhep-thInt.J.Mod.Phys.A(2018)·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.