Thu·Mar 3, 2016Thursday·March 3, 2016

1. 01*

   Generalizations of polylogarithms for Feynman integrals

   Christian Bogner🇩🇪

   In this talk, we discuss recent progress in the application of generalizations of polylogarithms in the symbolic computation of multi-loop integrals. We briefly review the Maple program MPL which supports a certain approach for the computation of Feynman integrals in terms of multiple polylogarithms. Furthermore we discuss elliptic generalizations of polylogarithms which have shown to be useful in the computation of the massive two-loop sunrise integral.

   hep-phhep-thJ.Phys.Conf.Ser.(2016)·5 citations
2. 02*

   Chern-Simons diffusion rate across different phase transitions

   Romulo Rougemont🇧🇷 · Stefano Ivo Finazzo🇧🇷

   We investigate how the dimensionless ratio given by the Chern-Simons diffusion rate ${\Gamma }_{\text{CS}}$ divided by the product of the entropy density $s$ and temperature $T$ behaves across different kinds of phase transitions in the class of bottom-up non-conformal Einstein-dilaton holographic models originally proposed by Gubser and Nellore. By tuning the dilaton potential, one is able to holographically mimic a first order, a second order, or a crossover transition. In a first order phase transition, ${\Gamma }_{\text{CS}}/sT$ jumps at the critical temperature (as previously found in the holographic literature), while in a second order phase transition it develops an infinite slope. On the other hand, in a crossover, ${\Gamma }_{\text{CS}}/sT$ behaves smoothly, although displaying a fast variation around the pseudo-critical temperature. In all the cases, ${\Gamma }_{\text{CS}}/sT$ increases with decreasing $T$. The behavior of the Chern-Simons diffusion rate across different phase transitions is expected to play a relevant role for the chiral magnetic effect around the QCD critical end point, which is a second order phase transition point connecting a crossover band to a line of first order phase transition. Our findings in the present work add to the literature the first predictions for the Chern-Simons diffusion rate across second order and crossover transitions in strongly coupled non-conformal, non-Abelian gauge theories.

   hep-phhep-lathep-thnucl-thPRD(2016)·4 citations
3. 03*

   Strong decay mode $J/\psi p$ of hidden charm pentaquark states $P_c^{+}(4380)$ and $P_c^{+}(4450)$ in ${\Sigma }_c{\bar{D}}^{\ast }$ molecular scenario

   Qi-Fang Lü🇨🇳 · Yu-Bing Dong🇨🇳

   We study the strong decay channels $P_c^{+}(4380)\to J/\psi p$ and $P_c^{+}(4450)\to J/\psi p$ under ${\Sigma }_c{\bar{D}}^{\ast }$ molecular state ansatz. With various spin-parity assignments, the partial decay widths of $J/\psi p$ final state are calculated. Our results show that all the $P$ wave ${\Sigma }_c{\bar{D}}^{\ast }$ assignments are excluded, while $S$ wave ${\Sigma }_c{\bar{D}}^{\ast }$ pictures for $P_c(4380)$ and $P_c(4450)$ are both allowed by present experimental data. The $J^P=3/2^{-}$ ${\Sigma }_c^{\ast }\bar{D}$ and ${\Sigma }_c^{\ast }{\bar{D}}^{\ast }$ molecules are also discussed in the heavy quark limit, and find that the ${\Sigma }_c^{\ast }\bar{D}$ system for $P_c(4380)$ is possible. More experimental information on spin-parities and partial decay widths and theoretical investigations on other decay modes are needed to clarify the nature of the two $P_c$ states.

   hep-phhep-exnucl-thPRD(2016)·82 citations
4. 04*

   CP violation in the extension of SM with a complex singlet scalar and vector quarks

   Neda Darvishi🇵🇱 · Maria Krawczyk🇵🇱

   We consider the simplest extension of the SM with a complex singlet and a pair of heavy doublet vector quarks, the so-called cSMCS model. In this model, the CP violation can emerge spontaneously as a consequence of the time-dependent phase of the complex singlet vacuum expectation value and the mass mixing of the SM and heavy vector quarks. In our model, the CP-violating time-dependent phase depends on the Higgs field within the bubble-wall via the Higgs-singlet coupling that can directly explain the observed baryon-to-entropy ratio $\sim 9\times 10^{-11}$. Additionally, as a result of the mixing between vector quarks and SM quarks, the tree level Flavour Changing Neutral Currents and the charged-current decay channels $t^{\prime }\to Wb,Zt,h_{i}t$ and $b^{\prime }\to Wt,Zb,h_{i}b$ would arise that are well constrained by experimental data. We investigate the implications of these constraints on the total cross-section for the production of heavy vector quark pairs via $pp\to t^{\prime }\overline{t^{\prime }}$ and $pp\to b^{\prime }\overline{b^{\prime }}$ channels and obtain the bounds on the heavy quark masses for this model. Accordingly, we show the contribution of these heavy quarks in the Higgs bosons signal strength, ${\mathcal{R}}_{\gamma \gamma }$, as well as corrections to the gauge boson propagators.

   hep-phNPB(2021)·17 citations
5. 05*

   Search for anomalous couplings via single top quark production in association with a photon at LHC

   Yu-Chen Guo🇨🇳 · Chong-Xing Yue🇨🇳 · Shuo Yang🇨🇳

   Considering the experimental constraints given by CMS collaboration at $\sqrt{s}=8$ TeV on the strength of top quark flavour-changing neutral-current (FCNC) couplings $tq\gamma$ and $tqg$, we investigate the production of top quark in association with a photon and carry out a full simulation for the signals $\ell \nu b\gamma$ and $jjb\gamma$ at 14 TeV LHC. In our numerical analysis, the contributions of single top production with a photon radiation off the top decay products are also included. The discovery potential for anomalous couplings $tq\gamma$ and $tqg$ with an integrated luminosity of 100 fb${}^{-1}$ are examined in detail.

   hep-phEPJC(2016)·19 citations
6. 06*

   Probing Neutrino Mass Hierarchy by Comparing the Charged-Current and Neutral-Current Interaction Rates of Supernova Neutrinos

   Kwang-Chang Lai🇹🇼 · Fei-Fan Lee🇹🇼 · Feng-Shiuh Lee🇹🇼 · Guey-Lin Lin🇹🇼 · Tsung-Che Liu🇹🇼 · Yi Yang🇹🇼

   The neutrino mass hierarchy is one of the neutrino fundamental properties yet to be determined. We introduce a method to determine neutrino mass hierarchy by comparing the interaction rate of neutral current (NC) interactions, $\nu (\hat{\nu })+p\to \nu (\hat{\nu })+p$, and inverse beta decays (IBD), ${\bar{\nu }}_e+p\to n+e^{+}$, of supernova neutrinos in scintillation detectors. Neutrino flavor conversions inside the supernova are sensitive to neutrino mass hierarchy. Due to Mikheyev-Smirnov-Wolfenstein effects, the full swapping of ${\bar{\nu }}_e$ flux with the ${\bar{\nu }}_x$ ($x=\mu ,\tau$) one occurs in the inverted hierarchy, while such a swapping does not occur in the normal hierarchy. As a result, more high energy IBD events occur in the detector for the inverted hierarchy than the high energy IBD events in the normal hierarchy. By comparing IBD interaction rate with the mass hierarchy independent NC interaction rate, one can determine the neutrino mass hierarchy.

   hep-phastro-ph.HEJCAP(2016)·10 citations
7. 07*

   Could the observation of $X(5568)$ be resulted by the near threshold rescattering effects?

   Xiao-Hai Liu🇯🇵 · Gang Li🇨🇳

   We investigate the invariant mass distributions of $B_s\pi$ via different rescattering processes. Because the triangle singularity (TS) could be present for a very broad incident energy region, it can be expected that the TS peaks may simulate the resonance-like bump $X(5568)$ observed by the D0 collaboration. The highly process-dependent characteristic of TS mechanism offers a criterion to distinguish it from other dynamic mechanisms.

   hep-phEPJC(2016)·57 citations
8. 08*

   Higgs mass and unified gauge coupling in the NMSSM with Vector Matter

   Riccardo Barbieri🇮🇹 · Dario Buttazzo🇨🇭 · Lawrence J. Hall🇺🇸 · David Marzocca🇨🇭

   We consider the NMSSM extended to include one vector-like family of quarks and leptons. If (some of) these vector-like matter particles, as the Higgs doublets, have Yukawa couplings to the singlet S that exceed unity at about the same scale $\Lambda \lesssim 10^3$ TeV, this gives the order 40 % enhancement of the tree level Higgs boson mass required in the MSSM to reach 125 GeV. It is conceivable that the Yukawa couplings to the singlet S, although naively blowing up close to $\Lambda$, will not spoil gauge coupling unification. In such a case the unified coupling ${\alpha }_X$ could be interestingly led to a value not far from unity, thus providing a possible explanation for the number of generations. The characteristic signal is an enhanced resonant production of neutral spin zero particles at LHC, that could even explain the putative diphoton resonance hinted by the recent LHC data at 750 GeV.

   hep-phJHEP(2016)·21 citations
9. 09*

   Cool quark matter

   Aleksi Kurkela🇨🇭 · Aleksi Vuorinen🇫🇮

   We generalize the state-of-the-art perturbative Equation of State of cold quark matter to nonzero temperatures, needed in the description of neutron star mergers and core collapse processes. The new result is accurate to order g^5 in the gauge coupling, and is based on a novel framework for dealing with the infrared sensitive soft field modes of the theory. The zero Matsubara mode sector is treated using a dimensionally reduced effective theory, while the soft non-zero modes are resummed using the Hard Thermal Loop approximation. This combination of known effective descriptions offers unprecedented access to small but nonzero temperatures, both in and out of beta equilibrium.

   hep-phastro-ph.HEnucl-thPRL(2016)·126 citations
10. 10*

    Non-Abelian Monopoles as the Origin of Dark Matter

    H. Falomir🇦🇷 · J. Gamboa🇨🇱 · F. Mendez🇨🇱

    We suggest that dark matter may be partially constituted by a dilute 't Hooft-Polyakov monopoles gas. We reach this conclusion by using the Georgi-Glashow model coupled to a dual kinetic mixing term $F\tilde{\mathcal{G}}$ where $F$ is the electromagnetic field and $\mathcal{G}$ the 't Hooft tensor. We show that these monopoles carry both (Maxwell) electric and (Georgi-Glashow) magnetic charges and the electric charge quantization condition is modified in terms of a dimensionless real parameter. This parameter could be determined from milli-charged particle experiments.

    ↳ hep-thhep-phMod.Phys.Lett.A(2016)·2 citations
11. 11*

    Did LIGO detect dark matter?

    Simeon Bird🇺🇸 · Ilias Cholis🇺🇸 · Julian B. Muñoz🇺🇸 · Yacine Ali-Haïmoud🇺🇸 · Marc Kamionkowski🇺🇸 · Ely D. Kovetz🇺🇸 · Alvise Raccanelli🇺🇸 · Adam G. Riess🇺🇸

    We consider the possibility that the black-hole (BH) binary detected by LIGO may be a signature of dark matter. Interestingly enough, there remains a window for masses $20M_{\odot }\lesssim M_{\mathrm{bh}}\lesssim 100M_{\odot }$ where primordial black holes (PBHs) may constitute the dark matter. If two BHs in a galactic halo pass sufficiently close, they radiate enough energy in gravitational waves to become gravitationally bound. The bound BHs will rapidly spiral inward due to emission of gravitational radiation and ultimately merge. Uncertainties in the rate for such events arise from our imprecise knowledge of the phase-space structure of galactic halos on the smallest scales. Still, reasonable estimates span a range that overlaps the $2-53$ Gpc${}^{-3}$ yr${}^{-1}$ rate estimated from GW150914, thus raising the possibility that LIGO has detected PBH dark matter. PBH mergers are likely to be distributed spatially more like dark matter than luminous matter and have no optical nor neutrino counterparts. They may be distinguished from mergers of BHs from more traditional astrophysical sources through the observed mass spectrum, their high ellipticities, or their stochastic gravitational wave background. Next generation experiments will be invaluable in performing these tests.

    ↳ astro-ph.COhep-phPRL(2016)·1395 citations
12. 12*

    The interplay of the sign problem and the infinite volume limit: gauge theories with a theta term

    Yiming Cai🇺🇸 · Thomas Cohen🇺🇸 · Ari Goldbloom-Helzner🇺🇸 · Brian McPeak🇺🇸

    QCD and related gauge theories have a sign problem when a $\theta$-term is included; this complicates the extraction of physical information from Euclidean space calculations as one would do in lattice studies. The sign problem arises in this system because the partition function for configurations with fixed topological charge $Q$, ${\mathcal{Z}}_Q$, are summed weighted by $\exp (iQ\theta )$ to obtain the partition function for fixed $\theta$, $\mathcal{Z}(\theta )$. The sign problem gets exponentially worse numerically as the space-time volume is increased. Here it is shown that apart from the practical numerical issues associated with large volumes, there are some interesting issues of principle. A key quantity is the energy density as a function of $\theta$, $\epsilon (\theta )=-\log \left(\mathcal{Z}(\theta )\right)/V$. This is expected to be well defined in the large 4-volume limit. Similarly, one expects the energy density for a fixed topological density $\tilde{\epsilon }(Q/V)=-\log \left({\mathcal{Z}}_Q\right)/V$ to be well defined in the limit of large 4-volumes. Intuitively, one might expect that if one had the infinite volume expression for $\tilde{\epsilon }(Q/V)$ to arbitrary accuracy, that one could reconstruct $\epsilon (\theta )$ by directly summing over the topological sectors of the partition function. We show here that there are circumstances where this is not the case. In particular, this occurs in regions where the curvature of $\epsilon (\theta )$ is negative.

    ↳ hep-lathep-phhep-thnucl-thPRD(2016)·3 citations
13. 13*

    Open Heavy Flavor in QCD Matter and in Nuclear Collisions

    Francesco Prino🇮🇹 · Ralf Rapp🇺🇸

    We review the experimental and theoretical status of open heavy-flavor (HF) production in high-energy nuclear collisions at RHIC and LHC. We first overview the theoretical concepts and pertinent calculations of HF transport in QCD matter, including perturbative and non-perturbative approaches in the quark-gluon plasma, effective models in hadronic matter, as well as implementations of heavy-quark (HQ) hadronization. This is followed by a brief discussion of bulk evolution models for heavy-ion collisions and initial conditions for the HQ distributions which are needed to calculate HF spectra in comparison to observables. We then turn to a discussion of experimental data that have been collected to date at RHIC and LHC, specifically for the nuclear suppression factor and elliptic flow of semileptonic HF decays, D mesons, non-prompt $J/\psi$ from B-meson decays, and b-jets. Model comparisons to HF data are conducted with regards to extracting the magnitude, temperature and momentum-dependence of HF transport coefficients from experiment.

    ↳ nucl-exhep-exhep-phnucl-thJ.Phys.G(2016)·221 citations
14. 14*

    Superplot: a graphical interface for plotting and analysing MultiNest output

    Andrew Fowlie🇦🇺 · Michael Hugh Bardsley

    We present an application, Superplot, for calculating and plotting statistical quantities relevant to parameter inference from a "chain" of samples drawn from a parameter space, produced by e.g. MultiNest. A simple graphical interface allows one to browse a chain of many variables quickly, and make publication quality plots of, inter alia, one- and two-dimensional profile likelihood, posterior pdf (with kernel density estimation), confidence intervals and credible regions. In this short manual, we document installation and basic usage, and define all statistical quantities and conventions. The code is fully compatible with Linux, Windows and Mac OSX. Furthermore, if preferred, all functionality is available through the command line rather than a graphical interface.

    ↳ physics.data-anastro-ph.IMhep-phEur.Phys.J.Plus(2016)·38 citations
15. 15*

    MHz Gravitational Waves from Short-term Anisotropic Inflation

    Asuka Ito🇯🇵 · Jiro Soda🇯🇵

    We reveal the universality of short-term anisotropic inflation. As a demonstration, we study inflation with an exponential type gauge kinetic function which is ubiquitous in models obtained by dimensional reduction from higher dimensional fundamental theory. It turns out that an anisotropic inflation universally takes place in the later stage of conventional inflation. Remarkably, we find that primordial gravitational waves with a peak amplitude around $10^{-26}$ ~ $10^{-27}$ are copiously produced in high-frequency bands 10MHz~100MHz. If we could detect such gravitational waves in future, we would be able to probe higher dimensional fundamental theory.

    ↳ hep-thastro-ph.COgr-qchep-phJCAP(2016)·51 citations
16. 16*

    Electric-Field-Induced Spin Resonance in Antiferromagnetic Insulators: Inverse Process of the Dynamical Chiral Magnetic Effect

    Akihiko Sekine🇯🇵 · Takahiro Chiba🇯🇵

    We propose a realization of the electric-field-induced antiferromagnetic resonance. We consider three-dimensional antiferromagnetic insulators with spin-orbit coupling characterized by the existence of a topological term called the $\theta$ term. By solving the Landau-Lifshitz-Gilbert equation in the presence of the $\theta$ term, we show that, in contrast to conventional methods using ac magnetic fields, the antiferromagnetic resonance state is realized by ac electric fields along with static magnetic fields. This mechanism can be understood as the inverse process of the dynamical chiral magnetic effect, an alternating current generation by magnetic fields. In other words, we propose a way to electrically induce the dynamical axion field in condensed matter. We discuss a possible experiment to observe our proposal, which utilizes the spin pumping from the antiferromagnetic insulator into a heavy metal contact.

    ↳ cond-mat.str-elcond-mat.mes-hallcond-mat.mtrl-scihep-lat+1PRB(2016)·10 citations
17. 17*

    Observational constraints and diagnostics for time-dependent dark energy models

    Deng Wang🇨🇳 · Xin-He Meng🇨🇳

    In this paper, we constrain four time-dependent dark energy (TDDE) models by using the Type Ia supernovae (SNe Ia), baryonic acoustic oscillations (BAO), observational Hubble parameter (OHD) data-sets as well as the single data point from the newest event GW150914. Subsequently, adopting the best fitting values of the model parameters, we apply the original statefinder, statefinder hierarchy, the growth rate of matter perturbations and $Om(z)$ diagnostics to distinguish the TDDE scenarios and the $\Lambda$CDM scenario from each other. We discover that all the TDDE models and $\Lambda$CDM model can be distinguished better at the present epoch by using the statefinder hierarchy than using the original statefinder, the growth rate of matter perturbations and $Om(z)$ diagnostics, especially, in the planes of $\{S_3^{(1)},S_4^{(1)}\}$, $\{S_3^{(2)},S_4^{(2)}\}$, $\{S_5^{(1)},S_5^{(2)}\}$ and $\{S_4^{(2)},S_5^{(2)}\}$.

    ↳ gr-qcastro-ph.COhep-ph4 citations
18. 18*

    Analysis on a Nambu--Jona-Lasinio Model of Dynamical Supersymmetry Breaking

    Yifan Cheng🇹🇼 · Yan-Min Dai🇹🇼 · Gaber Faisel🇹🇼 · Otto C. W. Kong🇹🇼

    This is a report on our newly proposed model of dynamical supersymmetry breaking with some details of the analysis involved. The model in the simplest version has only a chiral superfield (multiplet), with a strong four-superfield interaction in the Kähler potential that induces a real two-superfield composite with vacuum condensate. The latter has supersymmetry breaking parts, which we show to bear nontrivial solution following basically a standard nonperturbative analysis for a Nambu--Jona-Lasinio type model on a superfield setting. The real composite superfield has a spin one component but is otherwise quite unconventional. We discuss also the parallel analysis for the effective theory with the composite. Plausible vacuum solutions are illustrated and analyzed. The supersymmetry breaking solutions have generated soft mass(es) for the scalar avoiding the vanishing supertrace condition for the squared-masses of the superfield components. We also present some analysis of the resulted low energy effective theory with components of the composite become dynamical. The determinant of the fermionic modes is shown to be zero illustrating the presence of the expected Goldstino. The model gives the possibility of constructing a supersymmetric standard model with all (super)symmetry breaking masses generated dynamically and directly without the necessity of complicated hidden or mediating sectors.

    ↳ hep-thhep-ph2 citations
19. 19*

    Direct determinations of the nucleon and pion $\sigma$ terms at nearly physical quark masses

    Gunnar S. Bali🇩🇪 · Sara Collins🇩🇪 · Daniel Richtmann🇩🇪 · Andreas Schäfer🇩🇪 · Wolfgang Söldner🇩🇪 · André Sternbeck🇩🇪

    We present a high statistics study of the pion and nucleon light and strange quark sigma terms using $N_f=2$ dynamical non-perturbatively improved clover fermions with a range of pion masses down to $m_{\pi }\sim 150$ MeV and several volumes, $L{m}_{\pi }=3.4$ up to $6.7$, and lattice spacings, $a=0.06-0.08$ fm, enabling a study of finite volume and discretisation effects for $m_{\pi }\gtrsim 260$ MeV. Systematics are found to be reasonably under control. For the nucleon we obtain ${\sigma }_{\pi N}=35(6)$ MeV and ${\sigma }_s=35(12)$ MeV, or equivalently in terms of the quark fractions, $f_{T_u}=0.021(4)$, $f_{T_d}=0.016(4)$ and $f_{T_s}=0.037(13)$, where the errors include estimates of both the systematic and statistical uncertainties. These values, together with perturbative matching in the heavy quark limit, lead to $f_{T_c}=0.075(4)$, $f_{T_b}=0.072(2)$ and $f_{T_t}=0.070(1)$. In addition, through the use of the (inverse) Feynman-Hellmann theorem our results for ${\sigma }_{\pi N}$ are shown to be consistent with the nucleon masses determined in the analysis. For the pion we implement a method which greatly reduces excited state contamination to the scalar matrix elements from states travelling across the temporal boundary. This enables us to demonstrate the Gell-Mann-Oakes-Renner expectation ${\sigma }_{\pi }=m_{\pi }/2$ over our range of pion masses.

    ↳ hep-lathep-phPRD(2016)·119 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.