Fri·Jan 13, 2017Friday·January 13, 2017

1. 01*

   Dark Photons from Captured Inelastic Dark Matter Annihilation: Charged Particle Signatures

   Jordan Smolinsky🇺🇸 · Philip Tanedo🇺🇸

   The dark sector may contain a dark photon that kinetically mixes with the Standard Model photon, allowing dark matter to interact weakly with normal matter. In previous work we analyzed the implications of this scenario for dark matter capture by the Sun. Dark matter will gather in the core of the Sun and annihilate to dark photons. These dark photons travel outwards from the center of the Sun and may decay to produce positrons that can be detected by the Alpha Magnetic Spectrometer (AMS-02) on the ISS. We found that the dark photon parameter space accessible to this analysis is largely constrained by strong limits on the spin-independent WIMP-nucleon cross section from direct detection experiments. In this paper we build upon previous work by considering the case where the dark sector contains two species of Dirac fermion that are nearly degenerate in mass and couple inelastically to the dark photon. We find that for small values of the mass splitting $\Delta \sim 100\text{keV}$, the predicted positron signal at AMS-02 remains largely unchanged from the previously considered elastic case while constraints from direct detection are relaxed, leaving a region of parameter space with dark matter mass $100\text{GeV}\lesssim m_X\lesssim 10\text{TeV}$, dark photon mass $1\text{MeV}\lesssim m_{A^{\prime }}\lesssim 100\text{MeV}$, and kinetic mixing parameter $10^{-9}\lesssim \epsilon \lesssim 10^{-8}$ that is untouched by supernova observations and fixed target experiments but where an inelastic dark sector may still be discovered using existing AMS-02 data.

   hep-phastro-ph.COastro-ph.HEhep-exPRD(2017)·36 citations
2. 02*

   Interference Between Light and Heavy Neutrinos for $0\nu \beta \beta$ Decay in the Left-Right Symmetric Model

   Fahim Ahmed🇺🇸 · Andrei Neacsu🇺🇸 · Mihai Horoi🇺🇸

   Neutrinoless double-beta decay is proposed as an important low energy phenomenon that could test beyond the Standard Model physics. There are several potentially competing beyond the Standard Model mechanisms that can induce the process. It thus becomes important to disentangle the different processes. In the present study we consider the interference effect between the light left-handed and heavy right-handed Majorana neutrino exchange mechanisms. The decay rate, and consequently, the phase-space factors for the interference term are derived, based on the left-right symmetric model. The numerical values for the interference phase-space factors for several nuclides are calculated, taking into consideration the relativistic Coulomb distortion of the electron wave function and finite-size of the nucleus. The variation of the interference effect with the Q-value of the process is studied.

   hep-phnucl-thPLB(2017)·15 citations
3. 03*

   Search for a hidden strange baryon-meson bound state from $\varphi$ production in a nuclear medium

   Haiyan Gao🇺🇸 · Hongxia Huang🇨🇳 · Tianbo Liu🇺🇸 · Jialun Ping🇨🇳 · Fan Wang🇨🇳 · Zhiwen Zhao🇺🇸

   We investigate the hidden strange light baryon-meson system. With the resonating-group method, two bound states, ${\eta }^{\prime }-N$ and $\varphi -N$, are found in the quark delocalization color screening model. Focusing on the $\varphi -N$ bound state around 1950\,MeV, we obtain the total decay width of about 4\,MeV by calculating the phase shifts in the resonance scattering processes. To study the feasibility of an experimental search for the $\varphi -N$ bound state, we perform a Monte Carlo simulation of the bound state production with an electron beam and a gold target. In the simulation, we use the CLAS12 detector with the Forward Tagger and the BONUS12 detector in Hall B at Jefferson Lab. Both the signal and the background channels are estimated. We demonstrate that the signal events can be separated from the background with some momentum cuts. Therefore it is feasible to experimentally search for the $\varphi -N$ bound state through the near threshold $\varphi$ meson production from heavy nuclei.

   hep-phhep-exnucl-exnucl-thPRC(2017)·42 citations
4. 04*

   Study of the excited $1^{-}$ charm and charm-strange mesons

   Qiang Li🇨🇳 · Yue Jiang🇨🇳 · Tianhong Wang🇨🇳 · Han Yuan🇨🇳 · Guo-Li Wang🇨🇳 · Chao-Hsi Chang🇨🇳

   We give a systematical study on the recently reported excited charm and charm-strange mesons with potential $1^{-}$ spin-parity, including the $D_{s1}^{\ast }(2700{)}^{+}$, $D_{s1}^{\ast }(2860{)}^{+}$, $D^{\ast }(2600{)}^0$, $D^{\ast }(2650{)}^0$, $D_1^{\ast }(2680{)}^0$ and $D_1^{\ast }(2760{)}^0$. The main strong decay properties are obtained by the framework of Bethe-Salpeter (BS) methods. Our results reveal that the two $1^{-}$ charm-strange mesons can be well described by the further $2^3{S}_1$-$1^3{D}_1$ mixing scheme with a mixing angle of $8.7_{-3.2}^{+3.9}$ degrees. The predicted decay ratio $\frac{\mathcal{B}(D^{\ast }K)}{\mathcal{B}(DK)}$ for $D_{s1}^{\ast }(2860)$ is $0.62_{-0.12}^{+0.22}$.~$D^{\ast }(2600{)}^0$ can also be explained as the $2^3{S}_1$ predominant state with a mixing angle of $-(7.5_{-3.3}^{+4.0})$ degrees. Considering the mass range, $D^{\ast }(2650{)}^0$ and $D_1^{\ast }(2680{)}^0$ are more likely to be the $2^3{S}_1$ predominant states, although the total widths under both the $2^3{S}_1$ and $1^3{D}_1$ assignments have no great conflict with the current experimental data. The calculated width for LHCb $D_1^{\ast }(2760{)}^0$ seems about 100 \si{MeV} larger than experimental measurement if taking it as $1^3{D}_1$ or $1^3{D}_1$ dominant state $c\bar{u}$. The comparisons with other calculations and several important decay ratios are also present. For the identification of these $1^{-}$ charm mesons, further experimental information, such as $\frac{\mathcal{B}(D\pi )}{\mathcal{B}(D^{\ast }\pi )}$ are necessary.

   hep-phhep-exEPJC(2017)·13 citations
5. 05*

   Doubly-Heavy Baryon Weak Decays: ${\Xi }_{bc}^0\to p{K}^{-}$ and ${\Xi }_{cc}^{+}\to {\Sigma }_c^{++}(2520)K^{-}$

   Run-Hui Li🇨🇳 · Cai-Dian Lü🇨🇳 · Wei Wang🇨🇳 · Fu-Sheng Yu🇨🇳 · Zhi-Tian Zou🇨🇳

   Doubly-heavy baryons, with two heavy and one light quarks, are expected to exist in QCD and their masses have been predicted in the quark model. However their existence is not well established so far in experiment. In this work, we explore the possibility of searching for ${\Xi }_{bc}$ and ${\Xi }_{cc}^{+}$ in the $W$-exchange processes, ${\Xi }_{bc}^0\to p{K}^{-}$ and ${\Xi }_{cc}^{+}\to {\Sigma }_c^{++}(2520)K^{-}$. On the basis of perturbative calculations, we estimate the branching ratio of the first decay as $\mathcal{B}\mathcal{R}({\Xi }_{bc}^0\to p^{+}{K}^{-})\approx 3.21\times {\mathcal{R}}_f^2\times {\mathcal{R}}_{\tau }\times 10^{-7}$, where ${\mathcal{R}}_f$ (${\mathcal{R}}_{\tau }$) are the ratios of the decay constants (lifetimes) of ${\Xi }_{bc}^0$ and ${\Lambda }_b^0$. The branching ratio of ${\Xi }_{cc}^{+}\to {\Sigma }_c^{++}(2520)K^{-}$ is related to that of ${\Lambda }_c^{+}\to {\Delta }^{++}{K}^{-}$, and thereby a conjectured topology analysis leads to the range for the branching ratio as: $\mathcal{B}\mathcal{R}({\Xi }_{cc}^{+}\to {\Sigma }_c^{++}(2520)K^{-})\in \left[0.36\%,1.80\%\right]$. The decay ${\Xi }_{cc}^{+}\to {\Sigma }_c^{++}(2520)K^{-}$ would be reconstructed in the ${\Lambda }_c^{+}{K}^{-}{\pi }^{+}$ final state which is easy to access even at a hadron collider. Based on the two facts that abundant heavy quarks can be produced at a hadron collider like LHC, and the branching ratios of ${\Xi }_{bc}^0\to p{K}^{-}$ and ${\Xi }_{cc}^{+}\to {\Sigma }_c^{++}(2520)K^{-}$ are sizable, we urge our experimental colleagues to perform a search at LHCb. This will presumably lead to the discovery of the ${\Xi }_{bc}$ and ${\Xi }_{cc}^{+}$ , and precision measurements of the branching ratios in the future are helpful to investigate their decay mechanism.

   hep-phhep-exPLB(2017)·52 citations
6. 06*

   Quasi-real photon contribution to $A_N$ in $\ell p^{\uparrow }\to \pi$ X within a TMD approach

   Umberto D'Alesio🇮🇹 · Carlo Flore🇮🇹 · Francesco Murgia🇮🇹

   Within a TMD approach we discuss the impact of quasi-real (Weizsäcker-Williams) photon contribution to the transverse single-spin asymmetry, $A_N$, for the inclusive process $\ell p^{\uparrow }\to \pi X$. This study extends a previous one where only the leading-order contribution was taken into account. Predictions are obtained adopting the Sivers and transversity distributions and the Collins fragmentation functions as extracted from fits to the azimuthal asymmetries measured in semi-inclusive deep inelastic scattering and $e^{+}{e}^{-}$ annihilation processes. The description of the available data is very good, showing a clear general improvement with respect to the previous analysis (already quite promising). This result represents a further step towards a unified TMD treatment of SSAs in $\ell p^{\uparrow }\to {\ell }^{\prime }hX$ and $\ell p^{\uparrow }\to hX$ processes.

   hep-phPoS(2017)·2 citations
7. 07*

   Transverse Energy per Charged Particle in Heavy-Ion Collisions: Role of Collective Flow

   Swatantra Kumar Tiwari🇮🇳 · Raghunath Sahoo🇮🇳

   The ratio of (pseudo)rapidity density of transverse energy and the (pseudo)rapidity density of charged particles, which is a measure of the mean transverse energy per particle, is an important observable in high energy heavy-ion collisions, which reveals about the mechanism of particle production and the freeze-out criteria. Its collision energy and centrality dependence is exactly like the chemical freeze-out temperature till top RHIC energy. The LHC measurement at $\sqrt{s_{NN}}$ = 2.76 TeV brings up new challenges to rule out the mechanisms of gluon saturation or non-equilibrium phenomena being prevalent at high energies, which could contribute to the above observable. The Statistical Hadron Gas Model (SHGM) with a static fireball approximation has been successful in describing both the centrality and energy dependence till top RHIC energies. However, the SHGM predictions for higher energies are highly underestimated by the LHC data. In order to understand this, we have incorporated radial flow effect in an excluded volume SHGM. The hard-core radius of baryons at lower collision energies plays an important role in the description of a hadronic system. In view of this, in order to make a complete energy dependence study from FAIR to LHC energies, we have considered an excluded volume SHGM. Our studies suggest that the collective flow plays an important role in describing $E_T/N_{ch}$ and it could be one of the possible parameters to explain the jump observed in $E_T/N_{ch}$ from RHIC to LHC energies. Predictions for the LHC measurements at $\sqrt{s_{NN}}$ = 5.02 TeV are given.

   hep-phhep-exhep-thnucl-ex+1EPJA(2018)·5 citations
8. 08*

   The chiral anomaly, Berry's phase and chiral kinetic theory, from world-lines in quantum field theory

   Niklas Mueller🇩🇪 · Raju Venugopalan🇺🇸

   We outline a novel chiral kinetic theory framework for systematic computations of the Chiral Magnetic Effect (CME) in ultrarelativistic heavy-ion collisions. The real part of the fermion determinant in the QCD effective action is expressed as a supersymmetric world-line action of spinning, colored, Grassmanian point particles in background gauge fields, with equations of motion that are covariant generalizations of the Bargmann-Michel-Telegdi and Wong equations. Berry's phase is obtained in a consistent non-relativistic adiabatic limit. The chiral anomaly, in contrast, arises from the phase of the fermion determinant; its topological properties are therefore distinct from those of the Berry phase. We show that the imaginary contribution to the fermion determinant too can be expressed as a point particle world-line path integral and derive the corresponding anomalous axial vector current. Our results can be used to derive a covariant relativistic chiral kinetic theory including the effects of topological fluctuations that has overlap with classical-statistical simulations of the CME at early times and anomalous hydrodynamics at late times.

   hep-phhep-thnucl-thPRD(2018)·97 citations
9. 09*

   $t_{L,R}$ inclusive distributions as tests of top compositeness

   Fernand M. Renard🇫🇷

   We consider the inclusive top quark distributions in $e^{+}{e}^{-}\to t_{L,R}+\mathrm{anything}$. We analyze the modifications of the basic SM contributions which would result from $t_R$ compositeness for example from the presence of form factors in the $t_R$ couplings and of an effective top mass $m_t(s)$. We also look at parton like contributions representing additional new particle production related to $t_R$ constituents. One observes a large sensitivity of the $t_R$ inclusive distribution to these various effects with specific shapes differing from those of the $t_L$ distribution and we show that these effects may even be also observable in the unpolarized top case.

   hep-ph3 citations
10. 10*

    Excited muon searches at the FCC based muon-hadron colliders

    A. Caliskan🇹🇷 · S.O. Kara🇹🇷 · A. Ozansoy🇹🇷

    We study the excited muon production at the FCC based muon-hadron colliders. We give the excited muon decay widths and production cross section. We deal with the $\mu p\to {\mu }^{\star }q\to \mu \gamma q$ process and we plot the transverse momentum, rapidity and invariant mass distributions of final state particles to get the discovery cuts. By using discovery cuts, we get the mass limits for excited muons. It is shown that the discovery limits on the mass of ${\mu }^{\star }$ are 2.2 TeV, 5.9 TeV and 7.5 TeV for $\mu 63$-FCC, $\mu 750$-FCC and $\mu 1500$-FCC, respectively.

    hep-phAdv.High Energy Phys.(2017)·17 citations
11. 11*

    Axion astronomy with microwave cavity experiments

    Ciaran A. J. O'Hare🇬🇧 · Anne M. Green🇬🇧

    Terrestrial searches for the conversion of dark matter axions or axion-like particles into photons inside magnetic fields are sensitive to the phase space structure of the local Milky Way halo. We simulate signals in a hypothetical future experiment based on the Axion Dark Matter eXperiment (ADMX) that could be performed once the axion has been detected and a frequency range containing the axion mass has been identified. We develop a statistical analysis to extract astrophysical parameters, such as the halo velocity dispersion and laboratory velocity, from such data and find that with only a few days integration time a level of precision can be reached matching that of astronomical observations. For longer experiments lasting up to a year in duration we find that exploiting the modulation of the power spectrum in time allows accurate measurements of the Solar peculiar velocity with an accuracy that would improve upon astronomical observations. We also simulate signals based on results from N-body simulations and find that finer substructure in the form of tidal streams would show up prominently in future data, even if only a subdominant contribution to the local dark matter distribution. In these cases it would be possible to reconstruct all the properties of a dark matter stream using the time and frequency dependence of the signal. Finally we consider the detection prospects for a network of streams from tidally disrupted axion miniclusters. These features appear much more prominently in the resolved spectrum than suggested by calculations based on a scan over a range of resonant frequencies, making the detection of axion minicluster streams more viable than previously thought. These results confirm that haloscope experiments in a post-discovery era are able to perform "axion astronomy".

    ↳ astro-ph.COhep-phPRD(2017)·92 citations
12. 12*

    Cold dark matter plus not-so-clumpy dark relics

    Roberta Diamanti🇳🇱 · Shin'ichiro Ando (GRAPPA, U. of Amsterdam)🇳🇱 · Stefano Gariazzo🇪🇸 · Olga Mena (IFIC, U. of Valencia)🇪🇸 · Christoph Weniger (GRAPPA, U. of Amsterdam)🇳🇱

    Various particle physics models suggest that, besides the (nearly) cold dark matter that accounts for current observations, additional but sub-dominant dark relics might exist. These could be warm, hot, or even contribute as dark radiation. We present here a comprehensive study of two-component dark matter scenarios, where the first component is assumed to be cold, and the second is a non-cold thermal relic. Considering the cases where the non-cold dark matter species could be either a fermion or a boson, we derive consistent upper limits on the non-cold dark relic energy density for a very large range of velocity dispersions, covering the entire range from dark radiation to cold dark matter. To this end, we employ the latest Planck Cosmic Microwave Background data, the recent BOSS DR11 and other Baryon Acoustic Oscillation measurements, and also constraints on the number of Milky Way satellites, the latter of which provides a measure of the suppression of the matter power spectrum at the smallest scales due to the free-streaming of the non-cold dark matter component. We present the results on the fraction $f_{\mathrm{ncdm}}$ of non-cold dark matter with respect to the total dark matter for different ranges of the non-cold dark matter masses. We find that the 2$\sigma$ limits for non-cold dark matter particles with masses in the range 1--10 keV are $f_{\mathrm{ncdm}}\le 0.29$ (0.23) for fermions (bosons), and for masses in the 10--100 keV range they are $f_{\mathrm{ncdm}}\le 0.43$ (0.45), respectively.

    ↳ astro-ph.COhep-phJCAP(2017)·52 citations
13. 13*

    Hyperon threshold and stellar radii

    Luiz L. Lopes🇧🇷 · Debora P. Menezes🇧🇷

    We study how the $\Lambda$ hyperon threshold influences the radius of the canonical $1.4M_{\odot }$ neutron star in the light of the measurements found in the recent literature. We show that the onset of a new degree of freedom not only causes the well known reduction of the maximum mass, but also compacts the neutron stars with high central density. With the help of the strange mesons $\varphi$ and ${\sigma }^{\ast }$, we show that it is possible to simulate very compact neutron stars keeping realistic hyperon potentials, $U_{\Lambda }(n_0)=-28$ MeV and $U_{\Lambda }^{\Lambda }(n_0/5)$ in agreement with recents measurements. In the end we generalize these results showing that the onset of a yet not known dark matter particle with mass of 1.04 GeV is able to produce simultaneously a 2 $M_{\odot }$ neutron star and a canonical one with a radius of only 11.62 km.

    ↳ nucl-thastro-ph.HEhep-phJCAP(2018)·22 citations
14. 14*

    Symmetry restoration at high-temperature in two-color and two-flavor lattice gauge theories

    Jong-Wan Lee🇰🇷 · Biagio Lucini🇬🇧 · Maurizio Piai🇬🇧

    We consider the $SU(2)$ gauge theory with $N_f=2$ flavors of Dirac fundamental fermions. We study the high-temperature behavior of the spectra of mesons, discretizing the theory on anisotropic lattices, and measuring the two-point correlation functions in the temporal direction as well as screening masses in various channels. We identify the (pseudo-)critical temperature as the temperature at which the susceptibility associated with the Polyakov loop has a maximum. At high temperature both the spin-1 and spin-0 sectors of the light meson spectra exhibit enhanced symmetry properties, indicating the restoration of both the global $SU(4)$ and the axial $U(1{)}_A$ symmetries of the model.

    ↳ hep-lathep-phhep-thJHEP(2017)·36 citations
15. 15*

    Enhanced effect of CP-violating nuclear magnetic quadrupole moment in HfF${}^{+}$ molecule

    L.V. Skripnikov🇷🇺 · A.V. Titov🇷🇺 · V.V. Flambaum🇦🇺

    HfF${}^{+}$ cation is a very promising system to search for the electron electric dipole moment (EDM), and corresponding experiment is carried out by E. Cornell group. Here we theoretically investigate the cation to search for another T,P-odd effect -- the nuclear magnetic quadrpole moment (MQM) interaction with electrons. We report the first accurate ab initio relativistic electronic structure calculations of the molecular parameter $W_M$=0.494 $\frac{10^{33}\mathrm{Hz}}{e{\mathrm{cm}}^2}$ that is required to interpret the experimental data in terms of the MQM of Hf nucleus. For this we have implemented and applied the combined Dirac-Coulomb(-Gaunt) and relativistic effective core potential approaches to treat electron correlation effects from all of the electrons and to take into account high-order correlation effects using the coupled cluster method with single, double, triple and noniterative quadruple cluster amplitudes, CCSDT(Q). We discuss interpretation of the MQM effect in terms of the strength constants of T,P-odd nuclear forces, proton and neutron EDM, QCD parameter $\theta$ and quark chromo-EDM.

    ↳ physics.atom-phhep-phnucl-thphysics.chem-phPRA(2017)·35 citations
16. 16*

    Direct Probe of Dark Energy through Gravitational Lensing Effect

    Hong-Jian He🇨🇳 · Zhen Zhang🇨🇳

    We show that gravitational lensing can provide a direct method to probe the nature of dark energy at astrophysical scales. For lensing system as an isolated astrophysical object, we derive the dark energy contribution to gravitational potential as a repulsive power-law term, containing a generic equation of state parameter $w$. We find that it generates $w$-dependent and position-dependent modification to the conventional light orbital equation of $w=-1$. With post-Newtonian approximation, we compute its direct effect for an isolated lensing system at astrophysical scales and find that the dark energy force can deflect the path of incident light rays. We demonstrate that the dark-energy-induced deflection angle $\Delta {\alpha }_{DE}^{}\propto M^{(1+\frac{1}{3w})}$ (with $1+\frac{1}{3w}>0$), which increases with the lensing mass $M$ and consistently approaches zero in the limit $M\to 0$. This effect is distinctive because dark energy tends to diffuse the rays and generates concave lensing effect. This is in contrast to the conventional convex lensing effect caused by both visible and dark matter. Measuring such concave lensing effect can directly probe the existence and nature of dark energy. We estimate this effect and show that the current gravitational lensing experiments are sensitive to the direct probe of dark energy at astrophysical scales. For the special case $w=-1$, our independent study favors the previous works that the cosmological constant can affect light bending, although our prediction qualitatively and quantitatively differ from the literature, including our consistent realization of $\Delta {\alpha }_{DE}\to 0$ (under $M\to 0$) at the leading order.

    ↳ astro-ph.COastro-ph.GAgr-qchep-phJCAP(2017)·45 citations
17. 17*

    Towards Searching for Entangled Photons in the CMB Sky

    Jiunn-Wei Chen🇹🇼 · Shou-Huang Dai🇹🇼 · Debaprasad Maity🇮🇳 · Sichun Sun🇹🇼 · Yun-Long Zhang🇰🇷

    We explore the possibility of detecting entangled photon pairs from cosmic microwave background or other cosmological sources coming from two patches of the sky. The measurements use two detectors with different photon polarizer directions. When two photon sources are separated by a large angle relative to the earth, such that each detector has only one photon source in its field of view, a null test of unentangled photons can be performed. The deviation from this unentangled background is, in principle, the signature of photon entanglement. To confirm whether the deviation is consistent with entangled photons, we derive a photon polarization correlation to compare with, similar to that in a Bell inequality measurement. However, since photon coincidence measurement cannot be used to discriminate unentangled cosmic photons, it is unlikely that the correlation expectation value alone can violate Bell inequality to provide the signature for entanglement.

    ↳ quant-phastro-ph.COhep-phhep-thPRD(2019)·17 citations
18. 18*

    Supergravity and its Legacy

    S. Ferrara🇨🇭

    A personal recollection of events that preceded the construction of Supergravity and of some subsequent developments.

    ↳ physics.hist-phgr-qchep-phhep-thSubnucl.Ser.(2019)·0 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.