Fri·May 18, 2018Friday·May 18, 2018

1. 01*

   Two-loop corrections to false vacuum decay in scalar field theory

   M.A. Bezuglov🇷🇺 · A.I. Onishchenko🇷🇺

   We consider radiative corrections to false vacuum decay in a four-dimensional scalar field theory with cubic and quartic potential. Using planar thin wall approximation we were able to get analytical expression for the decay rate up to two loop order. The results obtained employ dimensional regularization and $\overline{MS}$ renormalization scheme.

   hep-phhep-thquant-phPLB(2019)·17 citations
2. 02*

   Octet and decuplet contribution to the proton self energy

   Hazhar Ghaderi🇸🇪

   Within the hadronic language of Chiral Perturbation Theory we present the full leading-order octet-baryon$-$meson and decuplet-baryon$-$meson contribution to the proton self energy and thus to its wave function renormalization factor $Z$. By Fock-expanding the physical proton state into its bare and hadron-cloud part, we show how each individual baryon-meson probability depend on the average momenta of the particles in the fluctuation. We present how the results depend on the choice of the form factor involved in the regularization (Gaussian or Besselian) and how they depend on the cut-off parameter. We also show how the results vary with respect to a variation of the decuplet coupling constant $h_A$. The momentum distributions of the fluctuations are given and the fluctuations' relative probabilities are presented. We show that for reasonable values of the cut-off parameter, the Delta-pion fluctuation is of the same strength as the nucleon-pion fluctuation.

   hep-ph2 citations
3. 03*

   The Photophobic ALP

   Nathaniel Craig🇺🇸 · Anson Hook🇺🇸 · Skyler Kasko🇺🇸

   We explore models and phenomenology of a photophobic axion-like particle (ALP), an axion whose coupling to photons is maximally suppressed without fine-tuning of the underlying parameters. We demonstrate that photophobia can be a natural UV property of ALP models and determine the irreducible coupling of photophobic ALPs to photons induced by violations of the axion shift symmetry. The signatures of photophobic axions are radically different from those of typical ALPs and are of particular interest for collider-based experiments, for which Standard Model triboson measurements provide a significant probe at higher masses. A variety of terrestrial and astrophysical measurements constrain the parameter space of photophobic ALPs, though bounds are typically much weaker compared to typical ALPs. We discuss implications for particle production relaxion models based on photophobic ALPs, finding that they are in mild tension with existing experimental constraints.

   hep-phJHEP(2018)·120 citations
4. 04*

   Analysis of the $b_1$ meson decay in local tensor bilinear representation

   Kie Sang Jeong🇰🇷 · Su Houng Lee🇰🇷 · Yongseok Oh🇰🇷

   We explore the validity of vector meson dominance in the radiative decay of the $b_1(1235)$ meson. In order to explain the violation of the vector meson dominance hypothesis in this decay process, we investigate a model where the $b_1$ meson strongly couples with the local current in tensor bilinear representation. The tensor representation is investigated in the framework of the operator product expansion and we found a low energy decay process that does not follow the usual vector meson dominance hypothesis. The $\omega$-like intermediate meson state of quantum numbers $I^G(J^{PC})=0^{-}(1^{--})$ is found to have a nontrivial role in the decay process of the $b_1$ meson. The spectral structure of the $\omega$-like state is found to be close to a $\pi$-$\rho$ hybrid state, which provides a mechanism that evades the usual vector meson dominance hypothesis. Precise measurements of various decay channels of the $b_1$ meson are, therefore, required to unravel the internal structure of axial vector mesons.

   hep-phhep-exnucl-thJHEP(2018)·7 citations
5. 05*

   Form factors for semileptonic $B_c$ decays into ${\eta }^{{(}^{\prime })}$ and Glueball

   Ruilin Zhu🇨🇳 · Yan Ma🇨🇳 · Xin-Ling Han🇨🇳 · Zhen-Jun Xiao🇨🇳

   We calculated the form factors of $B_c$ transitions into ${\eta }^{{(}^{\prime })}$ meson and pseudoscalar Glueball, where the $B_c$ meson is a bound state of two different heavy flavors and is treated as a nonrelativistic state, while the mesons ${\eta }^{{(}^{\prime })}$ and Glueball are treated as light-cone objects since their masses are smaller enough compared to the transition momentum scale. The mechanism of two gluon scattering into ${\eta }^{{(}^{\prime })}$ dominated the form factors of $B_c$ decays into ${\eta }^{{(}^{\prime })}$. We considered the $\eta -{\eta }^{\prime }-$Glueball mixing effect, and then obtained their influences on the form factors. The form factors of $B_c$ transitions into ${\eta }^{{(}^{\prime })}$ and pseudoscalar Glueball in the maximum momentum recoil point were obtained as follows: $f_{0,+}^{\eta }(q^2=0)=1.38_{-0.02}^{+0.00}\times 10^{-3}$,$f_{0,+}^{{\eta }^{\prime }}(q^2=0)=0.89_{-0.10}^{+0.11}\times 10^{-2}$ and $f_{0,+}^G(q^2=0)=0.44_{-0.05}^{+0.13}\times 10^{-2}$. Also phenomenological discussions for semileptonic $B_c\to {\eta }^{{(}^{\prime })}+\ell +{\bar{\nu }}_{\ell }$, $B_c\to G(0^{-+})+\ell +{\bar{\nu }}_{\ell }$ and $D_s\to \eta +\ell +{\bar{\nu }}_{\ell }$ decays are given.

   hep-phhep-exPRD(2018)·4 citations
6. 06*

   Forces inside hadrons: pressure, surface tension, mechanical radius, and all that

   Maxim V. Polyakov🇷🇺 · Peter Schweitzer🇺🇸

   The physics related to the form factors of the energy momentum tensor spans a wide spectrum of problems, and includes gravitational physics, hard exclusive reactions, hadronic decays of heavy quarkonia, and the physics of exotic hadrons described as hadroquarkonia. It also provides access to the "last global unknown property:" the D-term. We review the physics associated with the form factors of the energy-momentum tensor and the D-term, their interpretations in terms of mechanical properties, their applications, and the current experimental status.

   hep-phInt.J.Mod.Phys.A(2018)·509 citations
7. 07*

   Interpolating Quantum Electrodynamics between Instant and Front Forms

   Chueng-Ryong Ji🇺🇸 · Ziyue Li🇺🇸 · Bailing Ma🇺🇸 · Alfredo Takashi Suzuki🇧🇷

   The instant form and the front form of relativistic dynamics proposed by Dirac in 1949 can be linked by an interpolation angle parameter $\delta$ spanning between the instant form dynamics (IFD) at $\delta =0$ and the front form dynamics which is now known as the light-front dynamics (LFD) at $\delta =\pi /4$. We present the formal derivation of the interpolating quantum electrodynamics (QED) in the canonical field theory approach and discuss the constraint fermion degree of freedom which appears uniquely in the LFD. The constraint component of the fermion degrees of freedom in LFD results in the instantaneous contribution to the fermion propagator, which is genuinely distinguished from the ordinary equal-time forward and backward propagation of relativistic fermion degrees of freedom. As discussed in our previous work, the helicity of the on-mass-shell fermion spinors in LFD is also distinguished from the ordinary Jacob-Wick helicity in the IFD with respect to whether the helicity depends on the reference frame or not. To exemplify the characteristic difference of the fermion propagator between IFD and LFD, we compute the helicity amplitudes of typical QED processes such as $e^{+}{e}^{-}\to \gamma \gamma$ and $e\gamma \to e\gamma$ and present the whole landscape of the scattering amplitudes in terms of the frame dependence or the scattering angle dependence with respect to the interpolating angle dependence. Our analysis clarifies any conceivable confusion in the prevailing notion of the equivalence between the infinite momentum frame approach and the LFD.

   hep-phhep-thPRD(2018)·13 citations
8. 08*

   W boson polarization as a measure of gauge-Higgs anomalous couplings at the LHC

   Kumar Rao🇮🇳 · Saurabh Rindani🇮🇳

   We show how the $W$ boson polarization in the process of associated $W^{\pm }H$ production at the Large Hadron Collider (LHC) can be used to constrain anomalous $WWH$ couplings. We first calculate the spin density matrix for the $W$ to linear order in the anomalous couplings, which are assumed to be small. We then evaluate angular asymmetries in the decay distributions of leptons produced in the decay of the $W$ and show how they can be used to measure the individual elements of the polarization tensor. We estimate the limits that can be placed on the anomalous $WWH$ couplings at a future run of the LHC.

   hep-phNPB(2019)·10 citations
9. 09*

   Differential decay rates of CP-even and CP-odd Higgs bosons to top and bottom quarks at NNLO QCD

   Werner Bernreuther🇩🇪 · Long Chen🇩🇪 · Zong-Guo Si🇨🇳

   We consider the decay of a neutral Higgs boson of arbitrary CP nature to a massive quark antiquark pair at next-to-next-to-leading order in perturbative QCD. Our analysis is made at the differential level using the antenna subtraction framework. We apply our general set-up to the decays of a CP-even and CP-odd heavy Higgs boson to a top-quark top-antiquark pair and to the decay of the 125 GeV Higgs boson to a massive bottom-quark bottom-antiquark pair. In the latter case we calculate, in particular, the two-jet, three-jet, and four-jet decay rates and, for two-jet events, the energy distribution of the leading jet.

   hep-phhep-exJHEP(2018)·57 citations
10. 10*

    Utilising $B\to \pi K$ Decays at the High-Precision Frontier

    Robert Fleischer🇳🇱 · Ruben Jaarsma🇳🇱 · Eleftheria Malami🇳🇱 · K. Keri Vos🇩🇪

    For about twenty years, $B\to \pi K$ decays are in the focus of $B$-decay studies. We show that a correlation between the CP asymmetries of $B_d^0\to {\pi }^0{K}_{\mathrm{S}}$ reveals a tension with the Standard Model. Should it be due to New Physics, a modified electroweak penguin sector provides particularly interesting possibilities. We present a new method to determine the electroweak penguin parameters, which uses an isospin relation and requires only minimal $SU(3)$ input. We apply it to the current data for $B\to \pi K$ decays and discuss the prospects for utilizing CP violation in $B_d^0\to {\pi }^0{K}_{\mathrm{S}}$. The strategy has the exciting potential to establish New Physics in the electroweak penguin sector in the high-precision era of $B$-physics.

    hep-phhep-ex3 citations
11. 11*

    The large-Nc masses of light scalar mesons from QCD sum rules for linear radial spectrum

    S. S. Afonin🇷🇺 · T. D. Solomko🇷🇺

    We discuss a calculation of large-Nc masses of light scalar mesons from the QCD sum rules. Two methods based on the use of linear radial Regge trajectories are presented. We put a special emphasis on the appearance of pole near 0.5 GeV in the scalar isoscalar channel which emerges in both methods and presumably corresponds to the scalar sigma-meson.

    hep-phActa Phys.Polon.Supp.(2018)·2 citations
12. 12*

    Possible Molecular Pentaquark States with Different Spin and Quark Configurations

    K. Azizi🇹🇷 · Y. Sarac🇹🇷 · H. Sundu🇹🇷

    We investigate three possible pentaquark candidates, one of which contains a single charm quark and the other two contain triple charm quarks in their substructure. To this end we apply QCD sum rule method and take into account both the positive and negative parity states corresponding to each possible pentaquark channel having spin $3/2$ or $1/2$. Insisting on the importance of identification of the members of pentaquark family we obtain their spectroscopic parameters such as masses and residues. These parameters are the main inputs in the searches for their electromagnetic, strong and weak interactions.

    hep-phhep-exhep-latPRD(2018)·25 citations
13. 13*

    $B$ anomalies: From warped models to colliders

    Abhishek M. Iyer🇮🇹

    We address the anomalies in the semi leptonic decays of $B$ mesons in a warped custodial framework. Two possible solutions of lepton non-universality are discussed: A) The muon singlets couple non-universally to NP and B) The non-universality is in the coupling of lepton doublets. Both these scenarios are characterized by different predictions for rare Kaon decays. An essential feature of these scenarios is that the electron contribution to the Wilson coefficients (WC) is non-vanishing, thereby offering possibilities for different patterns of solutions. Beginning with a generic $Z^{\prime }$ model, we demonstrate how the observation of the ratio $N_{\mu \mu }/N_{ee}$ can be mapped to a given pattern of WC which satisfy the anomalies.

    hep-phhep-ex1 citation
14. 14*

    Decay behavior of the strange and beauty partners of $P_c$ hadronic molecules

    Yong-Hui Lin🇨🇳 · Chao-Wei Shen🇨🇳 · Bing-Song Zou🇨🇳

    We extend our previous study on the decay behavior of $P_c$ hadronic molecules to their strange and beauty partners. While $P_c(4380)$ and $P_c(4450)$ locate just below the $\bar{D}{\Sigma }_c^{\ast }$ and ${\bar{D}}^{\ast }{\Sigma }_c$ thresholds, respectively, their proposed strange partners $N(1875)$ and $N(2080)$ sit just below the $K{\Sigma }^{\ast }$ and $K^{\ast }\Sigma$ thresholds, respectively. Using the effective Lagrangian approach as the same as for the study of $P_c$ hadronic molecular states and with the couplings determined by the $\mathrm{SU}(3)$ flavor symmetry, the decay patterns of $N(1875)$ and $N(2080)$ are obtained assuming them to be the $S$-wave $K{\Sigma }^{\ast }$ and $K^{\ast }\Sigma$ molecules, respectively. It is found that the measured decay properties of $N(1875)$ and $N(2080)$ are reproduced well. Our results suggest that both $N(1875)$ and $N(2080)$ can be ascribed as the hadronic molecular pentaquark states in the hidden strangeness sector with quantum number $I(J^P)=1/2({3/2}^{-})$. Further checks on their hadronic molecule nature by various experiments are proposed. With the same approach, we also give our predictions for the decay behavior of the possible beauty partners of the $P_c$ hadronic molecular states. The $B^{\ast }{\Lambda }_b$ is found to be the largest decay mode for both $B{\Sigma }_b^{\ast }$ and $B^{\ast }{\Sigma }_b$ hadronic molecules, hence can be used to look for the hidden beauty pentaquark states in forthcoming experiments.

    hep-phnucl-thNPA(2018)·41 citations
15. 15*

    Composite Asymmetric Dark Matter with a Dark Photon Portal

    Masahiro Ibe🇯🇵 · Ayuki Kamada🇰🇷 · Shin Kobayashi🇯🇵 · Wakutaka Nakano🇯🇵

    Asymmetric dark matter (ADM) is an attractive framework relating the observed baryon asymmetry of the Universe to the dark matter density. A composite particle in a new strong dynamics is a promising candidate for ADM as the strong dynamics naturally explains the ADM mass in the GeV range. Its large annihilation cross section due to the strong dynamics leaves the asymmetric component to be dominant over the symmetric component. In such composite ADM scenarios, the dark sector has a relatively large entropy density in the early Universe. The large dark sector entropy results in the overclosure of the Universe or at best contradicts with the observations of the cosmic microwave background and the successful Big-Bang Nucleosynthesis. Thus, composite ADM models generically require some portal to transfer the entropy of the dark sector into the Standard Model sector. In this paper, we consider a dark photon portal with a mass in the sub-GeV range and kinetic mixing with the Standard Model photon. We investigate the viable parameter space of the dark photon in detail, which can find broad applications to dark photon portal models. We also provide a simple working example of composite ADM with a dark photon portal. Our model is compatible with thermal leptogenesis and $B-L$ symmetry. By taking into account the derived constraints, we show that the parameter space is largely tested by direct detection experiments.

    hep-phJHEP(2018)·54 citations
16. 16*

    A UV Complete Framework of Freeze-in Massive Particle Dark Matter

    Anirban Biswas🇮🇳 · Debasish Borah🇮🇳 · Arnab Dasgupta🇰🇷

    We propose a way to generate tiny couplings of freeze-in massive particle dark matter with the Standard Model particles dynamically by considering an extension of the electroweak gauge symmetry. The dark matter is considered to be a singlet under this extended gauge symmetry which we have assumed to be the one in a very widely studied scenario called left-right symmetric model. Several heavy particles, that can be thermally inaccessible in the early Universe due to their masses being greater than the reheat temperature after inflation, can play the role of portals between dark matter and Standard Model particles through one loop couplings. Due to the loop suppression, one can generate the required non-thermal dark matter couplings without any need of highly fine tuned Yukawa couplings beyond that of electron Yukawa with the Standard Model like Higgs boson. We show that generic values of Yukawa couplings as large as $\mathcal{O}(0.01)$ to $\mathcal{O}(1)$ can keep the dark matter out of thermal equilibrium in the early Universe and produce the correct relic abundance later through the freeze-in mechanism. Though the radiative couplings of dark matter are tiny as required by the freeze-in scenario, the associated rich particle sector of the model can be probed at ongoing and near future experiments. The allowed values of dark matter mass can remain in a wide range from keV to TeV order keeping the possibilities of warm and cold dark matter equally possible.

    hep-phPRD(2019)·46 citations
17. 17*

    Flavour Dynamics and Violations of the CP Symmetry

    Antonio Pich🇪🇸

    An overview of flavour physics and CP-violating phenomena is presented. The Standard Model quark-mixing mechanism is discussed in detail and its many successful experimental tests are summarized. Flavour-changing transitions put very stringent constraints on new-physics scenarios beyond the Standard Model framework. Special attention is given to the empirical evidences of CP violation and their important role in our understanding of flavour dynamics. The current status of the so-called flavour anomalies is also reviewed.

    hep-phhep-exCERN Yellow Rep.School Proc.(2018)·7 citations
18. 18*

    Stripping a supermultiplet of all but one scalar: a microscopic view

    Karim Benakli🇫🇷 · Yifan Chen🇫🇷

    We explain how a single scalar degree of freedom can be obtained from projecting out all the other components of a chiral superfield using simple operators in the microscopic theory. We use the Fayet-Iliopoulos model as an example of the origin for the necessary supersymmetry breaking. We also comment on one peculiar aspect where non-linear realisation can be useful: the freeze-in scenario for gravitino dark matter.

    ↳ hep-thhep-phPoS(2018)·0 citations
19. 19*

    Constraints on primordial black hole dark matter from Galactic center X-ray observations

    Andi Hektor🇪🇪 · Gert Hütsi🇪🇪 · Martti Raidal🇪🇪

    Surprisingly high masses of the black holes inferred from the LIGO & Virgo gravitational wave measurements have lead to speculations that the observed mergers might be due to $\mathcal{O}(10)M_{\odot }$ primordial black holes (PBHs). Furthermore, it has been suggested that the whole amount of dark matter (DM) might be in that exotic form. We investigate constraints on the PBH DM using NuSTAR Galactic center (GC) X-ray data. We used a robust Monte Carlo approach in conjunction with a radiatively inefficient PBH accretion model with commonly accepted model parameters. Compared to previous studies we allowed for multiple forms of DM density profiles. Most importantly, our study includes treatment of the gas turbulence, which significantly modifies the relative velocity between PBHs and gas. We show that inclusion of the effects of gas turbulence and the uncertainties related to the DM density profile reduces significantly the gas accretion onto PBHs compared to the claimed values in previous papers. It is highly improbable to obtain accreting PBHs brighter than the NuSTAR point source limit using observationally determined gas velocities. As such, one can safely conclude that GC X-ray observations cannot rule out $\mathcal{O}(10)M_{\odot }$ PBH DM.

    ↳ astro-ph.COhep-phAstron.Astrophys.(2018)·24 citations
20. 20*

    Search for gamma-ray emission from the nearby dwarf spheroidal galaxies with 9 years of Fermi-LAT data

    Shang Li🇨🇳 · Kai-Kai Duan🇨🇳 · Yun-Feng Liang🇨🇳 · Zi-Qing Xia🇨🇳 · Zhao-Qiang Shen🇨🇳 · Xiang Li🇨🇳 · Neng-Hui Liao🇨🇳 · Lei Feng🇨🇳 · Qiang Yuan🇨🇳 · Yi-Zhong Fan🇨🇳 · Jin Chang🇨🇳

    In this work, we search for $\gamma$-ray emission from the directions of some nearby Milky Way dwarf spheroidal galaxies (dSphs) and candidates with the publicly-available Pass 8 data of Fermi-LAT. Our sample includes 12 sources with the distances $<50$ kpc. Very weak $\gamma$-ray excesses ($\sim 2\sigma$) are found in some dSphs/candidates, consistent with that reported in the previous literature. Intriguingly, the peak test statistic (TS) value of the weak emission from the direction of Reticulum II rises continually. If interpreted as dark matter (DM) annihilation, the peak TS value is 13.5 for the annihilation channel of $\chi \chi \to {\tau }^{+}{\tau }^{-}$ and the DM mass of $m_{\chi }\sim 16$ GeV. The combination of all these nearby sources yields a more significant (with local significance $>4\sigma$) $\gamma$-ray signal.

    ↳ astro-ph.HEhep-phPRD(2018)·17 citations
21. 21*

    Chiral symmetry restoration by parity doubling and the structure of neutron stars

    Michał Marczenko🇵🇱 · David Blaschke🇵🇱 · Krzysztof Redlich🇵🇱 · Chihiro Sasaki🇵🇱

    We investigate the equation of state for a recently developed hybrid quark-meson-nucleon model under neutron star conditions of $\beta -$equilibrium and charge neutrality. The model has the characteristic feature that at increasing baryon density chiral symmetry is restored in a first order transition within the hadronic phase by lifting the mass splitting between chiral partner states, before quark deconfinement takes place. Most important for this study are the nucleon (neutron, proton) and $N(1535)$ states. We present three sets for the two free parameters which result in compact star mass-radius relations in accordance with modern constraints on the mass from PSR~J0437-4715 and on the compactness from GW170817. We also consider the threshold for the direct URCA process for which a new relationship is given and suggest as an additional constraint on the parameter choice of the model that this process shall become operative at best for stars with masses above the range for binary radio pulsars, $M>1.4M_{\odot }$.

    ↳ nucl-thastro-ph.HEhep-phPRD(2018)·69 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.