Thu·Aug 24, 2017Thursday·August 24, 2017

1. 01*

   General Mass Insertion Expansion in Flavor Physics

   Janusz Rosiek🇵🇱

   Calculating amplitudes for the flavor changing transitions in terms of the off-diagonal elements of mass matrices, so called "Mass Insertions" (MI) in the theory defined in "gauge basis" (before mass matrix diagonalization) is the common technique in analyzing the flavor structure of the New Physics models. I present a general method allowing to expand any QFT amplitude calculated in the mass-eigenstates (physical) basis into series in MI's, to any required order. The technique is purely algebraic, translating an amplitude written in the mass eigenbasis into MI series without performing diagrammatic calculations in the gauge basis. It can be applied for all types of mass matrices - either Hermitian (scalar or vector), general complex (Dirac fermions) or complex symmetric (Majorana fermions). Proposed expansion has been also automatized in the form of publicly available specialized Mathematica package, MassToMI, which features I illustrate with the example of the Higgs boson decays in the MSSM.

   hep-ph2 citations
2. 02*

   Wrong sign Yukawa coupling of the 2HDM plus a singlet scalar dark matter confronted with dark matter and Higgs data

   Lei Wang🇨🇳 · Rongle Shi🇨🇳 · Xiao-Fang Han🇨🇳

   In the framework of type-II two-Higgs-doublet model with a scalar dark matter ($S$), we examine the wrong sign Yukawa coupling of the 125 GeV Higgs which is the only portal between the dark matter and SM sectors. After imposing the constraints from the Higgs searches at the LHC and dark matter experiments, we obtain some interesting observables: (i) The theory, oblique parameters, and the Higgs searches at the LHC can impose stringent constraints on $\tan \beta$ in the case of the wrong sign Yukawa coupling of the 125 GeV Higgs. For example, for $m_H=600$ GeV and 140 GeV $<m_A<200$ GeV, $\tan \beta$ is required to be in the range of 4.2 and 5.7. (ii) Due to the contribution of $SS\to AA$ annihilation channel to the relic density, the dark matter coupling with the 125 GeV Higgs can be sizably suppressed. However, the $SS\to AA$ channel can not solve the tension between the relic density and the signal data of 125 GeV Higgs for $m_S<50$ GeV. (iii) The limits of XENON1T (2017) and PandaX-II (2017) exclude most of samples in the ranges of 65 GeV $<m_S<$ 78 GeV, $0.8<f^n/f^p<1$, and $y_d/y_u>-0.82$. (iv) The Fermi-LAT limits exclude most of samples in the range of 62.5 GeV $<m_S<65$ GeV, including the samples with $f^n/f^p\sim -0.7$.

   hep-phPRD(2017)·18 citations
3. 03*

   $D{D}^{\ast }$ potentials in chiral perturbation theory and possible molecular states

   Hao Xu🇨🇳 · Bo Wang🇨🇳 · Zhan-Wei Liu🇨🇳 · Xiang Liu🇨🇳

   The $D{D}^{\ast }$ potentials are studied within the framework of heavy meson chiral effective field theory. We obtain the effective potentials of the $D{D}^{\ast }$ system up to $O({ϵ}^2)$ at the one-loop level. In addition to the one-pion exchange contribution, the contact and two-pion exchange interactions are also investigated in detail. Furthermore, we search for the possible molecular states by solving the Schrödinger equation with the potentials. We notice that the contact and two-pion exchange potentials are numerically non-negligible and important for the existence of a bound state. In our results, no bound state is found in the $I=1$ channel within a wide range of cutoff parameter, while there exists a bound state in the $I=0$ channel as the cutoff is near $m_{\rho }$ in our approach.

   hep-phhep-exhep-latnucl-thPRD(2019)·73 citations
4. 04*

   Interplay between chiral symmetry breaking and the QCD Kondo effect

   Kei Suzuki🇯🇵 · Shigehiro Yasui🇯🇵 · Kazunori Itakura🇯🇵

   We investigate the interplay between the (light-light quark) chiral condensate and heavy-light quark condensate induced by the QCD Kondo effect, which is described by an effective Lagrangian with four-point interactions and the mean-field approximation. We find that the appearance of Kondo condensates decreases the critical chemical potential of the chiral condensate. In the region near the critical chemical potential, a coexistence phase with two kinds of condensates can appear. The behavior of such an interplay at finite temperature and with nonzero current light-quark mass is also discussed.

   hep-phnucl-thPRD(2017)·19 citations
5. 05*

   Next-to-leading-order electroweak corrections to the production of three charged leptons plus missing energy at the LHC

   Benedikt Biedermann🇩🇪 · Ansgar Denner🇩🇪 · Lars Hofer🇪🇸

   The production of a neutral and a charged vector boson with subsequent decays into three charged leptons and a neutrino is a very important process for precision tests of the Standard Model of elementary particles and in searches for anomalous triple-gauge-boson couplings. In this article, the first computation of next-to-leading-order electroweak corrections to the production of the four-lepton final states ${\mu }^{+}{\mu }^{-}{e}^{+}{\nu }_e$, ${\mu }^{+}{\mu }^{-}{e}^{-}{\bar{\nu }}_e$, ${\mu }^{+}{\mu }^{-}{\mu }^{+}{\nu }_{\mu }$, and ${\mu }^{+}{\mu }^{-}{\mu }^{-}{\bar{\nu }}_{\mu }$ at the Large Hadron Collider is presented. We use the complete matrix elements at leading and next-to-leading order, including all off-shell effects of intermediate massive vector bosons and virtual photons. The relative electroweak corrections to the fiducial cross sections from quark-induced partonic processes vary between $-3\%$ and $-6\%$, depending significantly on the event selection. At the level of differential distributions, we observe large negative corrections of up to $-30\%$ in the high-energy tails of distributions originating from electroweak Sudakov logarithms. Photon-induced contributions at next-to-leading order raise the leading-order fiducial cross section by $+2\%$. Interference effects in final states with equal-flavour leptons are at the permille level for the fiducial cross section, but can lead to sizeable effects in off-shell sensitive phase-space regions.

   hep-phhep-exJHEP(2017)·47 citations
6. 06*

   Disentangling the role of the $Y(4260)$ in $e^{+}{e}^{-}\to D^{\ast }{\bar{D}}^{\ast }$ and $D_s^{\ast }{\bar{D}}_s^{\ast }$ via line shape studies

   Si-Run Xue🇨🇳 · Hao-Jie Jing🇨🇳 · Feng-Kun Guo🇨🇳 · Qiang Zhao🇨🇳

   Whether the $Y(4260)$ can couple to open charm channels has been a crucial issue for understanding its nature. The available experimental data suggest that the cross section line shapes of exclusive processes in $e^{+}{e}^{-}$ annihilations have nontrivial structures around the mass region of the $Y(4260)$. As part of a series of studies of the $Y(4260)$ as mainly a $\bar{D}{D}_1(2420)+c.c.$ molecular state, we show that the partial widths of the $Y(4260)$ to the two-body open charm channels of $e^{+}{e}^{-}\to D^{\ast }{\bar{D}}^{\ast }$ and $D_s^{\ast }{\bar{D}}_s^{\ast }$ are much smaller than that to $\bar{D}{D}^{\ast }\pi +c.c.$. The line shapes measured by the Belle Collaboration for these two channels can be well described by the vector charmonium states $\psi (4040)$, $\psi (4160)$ and $\psi (4415)$ together with the $Y(4260)$. It turns out that the interference of the $Y(4260)$ with the other charmonia produces a dip around 4.22~GeV in the $e^{+}{e}^{-}\to D^{\ast }{\bar{D}}^{\ast }$ cross section line shape. The data also show an evidence for the strong coupling of the $Y(4260)$ to the $D{\bar{D}}_1(2420)$, in line with the expectation in the hadronic molecular scenario for the $Y(4260)$.

   hep-phhep-exnucl-exnucl-thPLB(2018)·23 citations
7. 07*

   Associated production of $Z$ bosons and $b$-jets at the LHC in the combined $k_T$ + collinear QCD factorization approach

   S.P. Baranov🇷🇺 · H. Jung🇩🇪 · A.V. Lipatov🇷🇺 · M.A. Malyshev🇷🇺

   We consider the production of $Z$ bosons associated with beauty quarks at the LHC using a combined $k_T$ + collinear QCD factorization approach, that interpolates between small $x$ and large $x$ physics. Our consideration is based on the off-shell gluon-gluon fusion subprocess $g^{\ast }{g}^{\ast }\to ZQ\bar{Q}$ at the leading order $\mathcal{O}(\alpha {\alpha }_s^2)$ (where the $Z$ boson further decays into a lepton pair), calculated in the $k_T$-factorization approach, and several subleading $\mathcal{O}(\alpha {\alpha }_s^2)$ and $\mathcal{O}(\alpha {\alpha }_s^3)$ subprocesses involving quark-antiquark and quark-gluon interactions, taken into account in conventional (collinear) QCD factorization. The contributions from double parton scattering are discussed as well. The transverse momentum dependent (or unintegrated) gluon densities in a proton are derived from Catani-Ciafaloni-Fiorani-Marchesini (CCFM) evolution equation. We achieve reasonably good agreement with the latest data taken by CMS and ATLAS Collaborations. The comparison of our results with next-to-leading-order pQCD predictions, obtained in the collinear QCD factorization, is presented. We discuss the uncertainties of our calculations and demonstrate the importance of subleading quark involving contributions in describing the LHC data in the whole kinematic region.

   hep-phEPJC(2017)·19 citations
8. 08*

   Running of the Spectrum of Cosmological Perturbations in String Gas Cosmology

   Robert Brandenberger🇨🇦 · Guilherme Franzmann🇨🇦 · Qiuyue Liang (McGill)🇨🇳

   We compute the running of the spectrum of cosmological perturbations in String Gas Cosmology, making use of a smooth parametrization of the transition between the early Hagedorn phase and the later radiation phase. We find that the running has the same sign as in simple models of single scalar field inflation. Its magnitude is proportional to $(1-n_s)$ ($n_s$ being the slope index of the spectrum), and it is thus parametrically larger than for inflationary cosmology, where it is proportional to $(1-n_s{)}^2$.

   ↳ hep-thastro-ph.COgr-qchep-phPRD(2017)·11 citations
9. 09*

   Remarks on the empirical accuracy of the optical superposition principle [Engl. transl. of Zh. Russk. Fiz.-Khim. Obshch., Ch. Fiz. 60(1928)555]

   S. I. Vavilov (Institute of Biological Physics, Moscow)🇸🇺

   English translation of a Russian article from 1928. Translator's abstract: The article presents general considerations on the validity of the superposition principle for light in vacuo from out a quantum theoretic point of view. It contains a report on an optical experiment designed to detect the phenomenon of photon-photon scattering. To understand the negative result of the performed experiment, a consideration of the solar corona is undertaken in order to derive an empirical upper limit on the photon-photon scattering rate. Source details: S. I. Vavilov: Zamechaniya ob empiricheskoi tochnosti opticheskogo printsipa superpozitsii. Zhurnal Russkogo Fiziko-Khimicheskogo Obshchestva pri Leningradskom Universitete, Chast' Fizicheskaya [Journal of the Russian Physico-Chemical Society at Leningrad University, Physical Part], Vol. LX (1928) No. 6, pp. 555-563.

   ↳ physics.hist-phhep-phquant-phZh.Russk.Fiz.Khim.Obshch.Ch.Fiz.(1928)·25 citations
10. 10*

    Dark Matter Results From 54-Ton-Day Exposure of PandaX-II Experiment

    PandaX-II Collaboration: Xiangyi Cui🇨🇳 · Abdusalam Abdukerim🇨🇳 · Wei Chen🇨🇳 · Xun Chen🇨🇳 · Yunhua Chen🇨🇳 · Binbin Dong🇨🇳 · Deqing Fang🇨🇳 · Changbo Fu🇨🇳 · Karl Giboni🇨🇳 · Franco Giuliani🇨🇳 · Linhui Gu🇨🇳 · Yikun Gu🇨🇳 and 44 other authors

    We report a new search of weakly interacting massive particles (WIMPs) using the combined low background data sets in 2016 and 2017 from the PandaX-II experiment in China. The latest data set contains a new exposure of 77.1 live day, with the background reduced to a level of 0.8$\times 10^{-3}$ evt/kg/day, improved by a factor of 2.5 in comparison to the previous run in 2016. No excess events were found above the expected background. With a total exposure of 5.4$\times 10^4$ kg day, the most stringent upper limit on spin-independent WIMP-nucleon cross section was set for a WIMP with mass larger than 100 GeV/c${}^2$, with the lowest exclusion at 8.6$\times 10^{-47}$ cm${}^2$ at 40 GeV/c${}^2$.

    ↳ astro-ph.COhep-exhep-phphysics.ins-detPRL(2017)·1229 citations
11. 11*

    The Viability of Phantom Dark Energy: A Brief Review

    Kevin J. Ludwick🇺🇸

    In this brief review, we examine the theoretical consistency and viability of phantom dark energy. Almost all data sets from cosmological probes are compatible with dark energy of the phantom variety (i.e., equation-of-state parameter $w<-1$) and may even favor evolving dark energy, and since we expect every physical entity to have some kind of field description, we set out to examine the case for phantom dark energy as a field theory. We discuss the many attempts at frameworks that may mitigate and eliminate theoretical pathologies associated with phantom dark energy. We also examine frameworks that provide an apparent measurement $w<-1$ while avoiding the need for a phantom field theory.

    ↳ astro-ph.COgr-qchep-phMod.Phys.Lett.A(2017)·101 citations
12. 12*

    Thermal entropy of a quark-antiquark pair above and below deconfinement from a dynamical holographic QCD model

    David Dudal🇧🇪 · Subhash Mahapatra🇧🇪

    We discuss the entropy carried by a quark-antiquark pair, in particular across the deconfinement transition. We therefore rely on a self-consistent solution to Einstein-Maxwell-dilaton gravity, capable of mimicking essential features of QCD. In particular we introduce a novel model that still captures well the QCD confinement and deconfinement phases, while allowing the introduction of a temperature in a phase which resembles the confined phase, this thanks to it being dual to a small black hole. We pay due attention to some subtleties of such model. We confirm the lattice picture of a strong build-up of thermal entropy towards the critical temperature T_c, both coming from below or above T_c. We also include a chemical potential, confirming this entropic picture and we consider its effect on the speed of sound. Moreover, the temperature dependent confinement phase from the holography side allows us to find a string tension that does not vanish at T_c, a finding also supported by lattice QCD.

    ↳ hep-thhep-lathep-phPRD(2017)·97 citations
13. 13*

    Cosmic viscosity as a remedy for tension between PLANCK and LSS data

    Sampurn Anand🇮🇳 · Prakrut Chaubal🇮🇳 · Arindam Mazumdar🇮🇳 · Subhendra Mohanty🇮🇳

    Measurements of ${\sigma }_8$ from large scale structure observations show a discordance with the extrapolated ${\sigma }_8$ from Planck CMB parameters using $\Lambda$CDM cosmology. Similar discordance is found in the value of $H_0$ and ${\Omega }_m$. In this paper, we show that the presence of viscosity in cold dark matter, shear or bulk or combination of both, can remove the above mentioned conflicts simultaneously. This indicates that the data from Planck CMB observation and different LSS observations prefer small but non-zero amount of viscosity in cold dark matter fluid.

    ↳ astro-ph.COhep-phJCAP(2017)·68 citations
14. 14*

    A Universal Constraint on the Infrared Behavior of the Ghost Propagator in QCD

    Fei Gao🇨🇳 · Can Tang🇨🇳 · Yu-xin Liu🇨🇳

    With proposing a unified description of the fields variation at the level of generating functional, we obtain a new identity for the quark-gluon interaction vertex based on gauge symmetry, which is similar to the Slavnov-Taylor Identities(STIs) based on the Becchi-Rouet-Stora-Tyutin transformation. With these identities, we find that in Landau gauge, the dressing function of the ghost propagator approaches to a constant as its momentum goes to zero, which provides a strong constraint on the infrared behaviour of ghost propagator.

    ↳ hep-thhep-phPLB(2017)·7 citations
15. 15*

    The double copy: gravity from gluons

    Chris D. White🇬🇧

    Three of the four fundamental forces in nature are described by so-called gauge theories, which include the effects of both relativity and quantum mechanics. Gravity, on the other hand, is described by General Relativity, and the lack of a well-behaved quantum theory - believed to be relevant at the centre of black holes, and at the Big Bang itself - remains a notorious unsolved problem. Recently a new correspondence, the double copy, has been discovered between scattering amplitudes (quantities related to the probability for particles to interact) in gravity, and their gauge theory counterparts. This has subsequently been extended to other quantities, providing gauge theory analogues of e.g. black holes. We here review current research on the double copy, and describe some possible applications.

    ↳ hep-thgr-qchep-phphysics.pop-phContemp.Phys.(2018)·29 citations
16. 16*

    High-Energy Neutrino Emission from Short Gamma-Ray Bursts: Prospects for Coincident Detection with Gravitational Waves

    Shigeo S. Kimura🇺🇸 · Kohta Murase🇺🇸 · Peter Mészáros🇺🇸 · Kenta Kiuchi🇯🇵

    We investigate current and future prospects for coincident detection of high-energy neutrinos and gravitational waves (GWs). Short gamma-ray bursts (SGRBs) are believed to originate from mergers of compact star binaries involving neutron stars. We estimate high-energy neutrino fluences from prompt emission, extended emission, X-ray flares, and plateau emission, and show that neutrino signals associated with the extended emission are the most promising. Assuming that the cosmic-ray loading factor is $\sim 10$ and the Lorentz factor distribution is lognormal, we calculate the probability of neutrino detection from extended emission by current and future neutrino detectors, and find that the quasi-simultaneous detection of high-energy neutrinos, gamma rays, and GWs is possible with future instruments or even with current instruments for nearby SGRBs having extended emission. We also discuss stacking analyses that will also be useful with future experiments such as IceCube-Gen2.

    ↳ astro-ph.HEgr-qchep-phApJL(2017)·155 citations
17. 17*

    Axion field induces exact symmetry

    P. Mitra🇮🇳

    While no regularization is consistent with the anomalous chiral symmetry which occurs for massless fermions, the artificial axion-induced symmetry for massive fermions is shown here to be consistent with a standard regularization, even in curved spacetime, so that it can be said to have no anomaly in gauge or gravitational fields. Implications for theta terms are pointed out.

    ↳ hep-thhep-phJ.Phys.Comm.(2017)·1 citation

* 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.