Tue·Apr 18, 2017Tuesday·April 18, 2017

1. 01*

   DsixTools: The Standard Model Effective Field Theory Toolkit

   Alejandro Celis🇩🇪 · Javier Fuentes-Martin🇪🇸 · Avelino Vicente🇪🇸 · Javier Virto🇨🇭

   We present DsixTools, a Mathematica package for the handling of the dimension-six Standard Model Effective Field Theory. Among other features, DsixTools allows the user to perform the full one-loop Renormalization Group Evolution of the Wilson coefficients in the Warsaw basis. This is achieved thanks to the SMEFTrunner module, which implements the full one-loop anomalous dimension matrix previously derived in the literature. In addition, DsixTools also contains modules devoted to the matching to the $\Delta B=\Delta S=1,2$ and $\Delta B=\Delta C=1$ operators of the Weak Effective Theory at the electroweak scale and their QCD and QED Renormalization Group Evolution below the electroweak scale.

   hep-phEPJC(2017)·193 citations
2. 02*

   Axion-like particle assisted strongly interacting massive particle

   Ayuki Kamada🇰🇷 · Hyungjin Kim🇰🇷 · Toyokazu Sekiguchi🇰🇷

   We propose a new realization of strongly interacting massive particles (SIMP) as self-interacting dark matter, where SIMPs couple to the Standard Model sector through an axion-like particle. Our model gets over major obstacles accompanying the original SIMP model, such as a missing mechanism of kinetically equilibrating SIMPs with the SM plasma as well as marginal perturbativity of the chiral Lagrangian density. Remarkably, the parameter region realizing ${\sigma }_{\mathrm{self}}/m_{\mathrm{DM}}\simeq 0.1\text{–}1{\mathrm{cm}}^2/\mathrm{g}$ is within the reach of future beam dump experiments such as the Search for Hidden Particles (SHiP) experiment.

   hep-phastro-ph.COPRD(2017)·28 citations
3. 03*

   CP asymmetries in $D\to P{P}^{\prime }$ decays

   Ulrich Nierste🇩🇪 · Stefan Schacht🇮🇹

   This talk addresses two topics related to CP asymmetries in $D$ meson decays to two pseudoscalar mesons. First I discuss how new physics can be distinguished from the Standard Model through two sum rules relating three direct CP asymmetries each, using the sum rule correlating $D^0\to K^{+}{K}^{-}$, $D^0\to {\pi }^{+}{\pi }^{-}$, and $D^0\to {\pi }^0{\pi }^0$ for illustration. The other sum rule involves $a_{CP}^{\mathrm{dir}}(D^{+}\to {\bar{K}}^0{K}^{+})$, $a_{CP}^{\mathrm{dir}}(D_s^{+}\to K^0{\pi }^{+})$, and $a_{CP}^{\mathrm{dir}}(D_s^{+}\to K^{+}{\pi }^0)$. The second topic is the direct CP asymmetry in the decay $D^0\to K_S{K}_S$, which is expected to be large in the Standard Model for two reasons: Flavor-SU(3) symmetry suppresses the tree amplitude which enhances the crucial "penguin-to-tree" ratio and the "penguin" amplitude is dominated by the tree-level $W$ boson exchange between $c$ and $u$ quarks. We find that $|a_{CP}^{\mathrm{dir}}(D^0\to K_S{K}_S)|$ can be as large as $1.1\%$ in the Standard Model. We advocate $D^0\to K_S{K}_S$ as a discovery channel for charm CP violation.

   hep-phPoS(2016)·4 citations
4. 04*

   Structure of virtual photon polarization in ultrarelativistic heavy-ion collisions

   Gordon Baym🇺🇸 · Tetsuo Hatsuda🇯🇵 · Michael Strickland🇺🇸

   Anisotropy in heavy-ion collisions leads to polarization of both direct and virtual photons, the latter detected via internal conversion to dileptons pairs. Thus measurement of photon polarization probes the anisotropy at all stages of collisions. In order to characterize the polarization of virtual photons, we derive here the general structure of the photon polarization operator, rho^(mu nu), in an anisotropic medium, in terms of the four spectral functions, two transverse and one longitudinal, as usual, plus a new spectral function that reflects anisotropy in asymmetric collisions; and derive the local production rate of dilepton pairs in terms of these four functions.

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

   Penguin pollution in $\beta$ and ${\beta }_s$

   Ulrich Nierste🇩🇪

   The mixing-induced CP asymmetries in $B_d\to J/\psi K_S$ and $B_s\to J/\psi \varphi$ are essential to detect or constrain new physics in the $B_d-\overline{B}{}_d$ and $B_s-\overline{B}{}_s$ mixing amplitudes, respectively. To this end one must control the penguin contributions to the decay amplitudes, which affect the extraction of fundamental CP phases from the measured CP asymmetries. Although the "penguin pollution" is doubly Cabibbo-suppressed, it could compete in size with current experimental errors. In this talk I present a calculation of the penguin contributions treating QCD effects with soft-collinear factorisation and compare method and results with the alternative approach employing flavour-SU(3) symmetry. As a novel feature, I present results for the penguin pollution in $b\to c\overline{c}d$ modes.

   hep-phPoS(2017)·2 citations
6. 06*

   Nucleon resonances in $\gamma p\to K^{\ast +}\Lambda$

   A. C. Wang🇨🇳 · W. L. Wang🇨🇳 · F. Huang🇨🇳 · H. Haberzettl🇺🇸 · K. Nakayama🇺🇸

   The high-precision cross-section data for the reaction $\gamma p\to K^{\ast +}\Lambda$ reported by the CLAS Collaboration at the Thomas Jefferson National Accelerator Facility have been analyzed based on an effective Lagrangian approach in the tree-level approximation. Apart from the $t$-channel $K$, $\kappa$, $K^{\ast }$ exchanges, the $s$-channel nucleon ($N$) exchange, the $u$-channel $\Lambda$, $\Sigma$, ${\Sigma }^{\ast }(1385)$ exchanges, and the generalized contact term, the contributions from the near-threshold nucleon resonances in the $s$-channel are also taken into account in constructing the reaction amplitude. It is found that, to achieve a satisfactory description of the differential cross section data, at least two nucleon resonances should be included. By including the $N(2060){5/2}^{-}$ resonance, which is responsible for the shape of the angular distribution near the $K^{\ast }\Lambda$ threshold, and one of the $N(2000){5/2}^{+}$, $N(2040){3/2}^{+}$, $N(2100){1/2}^{+}$, $N(2120){3/2}^{-}$ and $N(2190){7/2}^{-}$ resonances, one can describe the cross-section data quite well, with the fitted resonance masses and widths compatible with those advocated by the Particle Data Group. The resulted predictions of the beam, target, and recoil asymmetries are found to be quite different from various fits, indicating the necessity of the spin observable data for $\gamma p\to K^{\ast +}\Lambda$ to further pin down the resonance contents and associated parameters in this reaction.

   hep-phPRC(2017)·41 citations
7. 07*

   A Unified Description for Comprehensive Sets of Jet Energy Loss Observables with CUJET3

   Shuzhe Shi🇺🇸 · Jiechen Xu🇺🇸 · Jinfeng Liao🇺🇸 · Miklos Gyulassy🇺🇸

   Jet energy loss in heavy ion collisions, as quantified by the traditional observable of high $p_T$ hadron's nuclear modification factor $R_{AA}$, provides highly informative "imaging" of the hot medium created in heavy ion collisions. There are now comprehensive sets of available data, from average suppression to azimuthal anisotropy, from light to heavy flavors, from RHIC 200GeV to LHC 2.76TeV as well as 5.02TeV collisions. A unified description of such comprehensive data presents a stringent vetting of any viable model for jet quenching phenomenology. In this contribution we report such a systematic and successful test of CUJET3, a jet energy loss simulation framework built upon a nonperturbative microscopic model for the hot medium as a semi-quark-gluon-monopole plasma (sQGMP) which integrates two essential elements of confinement, i.e. the Polyakov-loop suppression of quarks/gluons and emergent magnetic monopoles.

   hep-phnucl-exnucl-thNPA(2017)·9 citations
8. 08*

   Weak quasielastic electroproduction of hyperons with polarization observables

   F. Akbar🇮🇳 · M. Sajjad Athar🇮🇳 · A. Fatima🇮🇳 · S. K. Singh🇮🇳

   With the availability of high luminosity electron beam at the accelerators, there is now the possibility of studying weak quasielastic hyperon production off the proton, i.e. $e^{-}p\to {\nu }_{e}Y(Y=\Lambda ,{\Sigma }^0)$, which will enable the determination of the nucleon-hyperon vector and axial-vector transition form factors at high $Q^2$ in the strangeness sector and provide test of the Cabibbo model, G-invariance, CVC, PCAC hypotheses and SU(3) symmetry. In this work, we have studied the total cross section, differential cross section as well as the longitudinal and perpendicular components of polarization of the final hyperons ($\Lambda$ and ${\Sigma }^0$ produced in these reactions) and presented numerical results for these observables and their sensitivity to the transition form factors.

   hep-phEPJA(2017)·17 citations
9. 09*

   Spontaneous Spin Polarization due to Tensor Selfenergies in Quark Matter

   Tomoyuki Maruyama🇯🇵 · Toshitaka Tatsumi🇯🇵

   We study the magnetic properties of quark matter in the NJL model with the tensor interaction. The spin-polarized phase given by the tensor interaction remains even when the quark mass is zero, while the phase given by the axial vector interaction disappears. There are two kinds of spin-polarized phases: one appears in the chiral-broken phase, and the other appears in the chiral-restored phase where the quark mass is zero. The latter phase can appear independently of the strength of the tensor interaction.

   hep-phnucl-thPRD(2017)·9 citations
10. 10*

    Search for a compressed supersymmetric spectrum with a light Gravitino

    Juhi Dutta🇮🇳 · Partha Konar🇮🇳 · Subhadeep Mondal🇮🇳 · Biswarup Mukhopadhyaya🇮🇳 · Santosh Kumar Rai🇮🇳

    Presence of the light gravitino as dark matter candidate in a supersymmetric (SUSY) model opens up interesting collider signatures consisting of one or more hard photons together with multiple jets and missing transverse energy from the cascade decay. We investigate such signals at the 13 TeV LHC in presence of compressed SUSY spectra, consistent with the Higgs mass as well as collider and dark matter constraints. We analyse and compare the discovery potential in different benchmark scenarios consisting of both compressed and uncompressed SUSY spectra, considering different levels of compression and intermediate decay modes. Our conclusion is that compressed spectra upto 2.5 TeV are likely to be probed even before the high luminosity run of LHC. Kinematic variables are also suggested, which offer distinction between compressed and uncompressed spectra yielding similar event rates for photons + multi-jets + $E{/}_T$.

    hep-phhep-exJHEP(2017)·15 citations
11. 11*

    Fermion Dark Matter in Gauge-Higgs Unification

    Nobuhito Maru🇯🇵 · Takashi Miyaji🇯🇵 · Nobuchika Okada🇺🇸 · Satomi Okada🇯🇵

    We propose a Majorana fermion dark matter in the context of a simple gauge-Higgs Unification (GHU) scenario based on the gauge group $SU(3)$ x $U(1{)}^{\prime }$ in 5-dimensional Minkowski space with a compactification of the 5th dimension on $S^1/Z_2$ orbifold. The dark matter particle is identified with the lightest mode in $SU(3)$ triplet fermions additionally introduced in the 5-dimensional bulk. We find an allowed parameter region for the dark matter mass around a half of the Standard Model Higgs boson mass, which is consistent with the observed dark matter density and the constraint from the LUX 2016 result for the direct dark matter search. The entire allowed region will be covered by, for example, the LUX-ZEPLIN dark matter experiment in the near future. We also show that in the presence of the bulk $SU(3)$ triplet fermions the 125 GeV Higgs boson mass is reproduced through the renormalization group evolution of Higgs quartic coupling with the compactification scale of around $10^8$ GeV.

    hep-phhep-thJHEP(2017)·20 citations
12. 12*

    Inception of Self-Interacting Dark Matter with Dark Charge Conjugation Symmetry

    Ernest Ma (UC Riverside)🇺🇸

    A new understanding of the stability of self-interacting dark matter is pointed out, based on the simplest spontaneously broken Abelian $U(1)$ gauge model with one complex scalar and one Dirac fermion. The key is the imposition of dark charge conjugation symmetry. It allows the possible existence of two stable particles: the Dirac fermion and the vector gauge boson which acts as a light mediator for the former's self-interaction. Since this light mediator does not decay, it avoids the strong cosmological constraints recently obtained for all such models where the light mediator decays into standard-model particles.

    hep-phastro-ph.COPLB(2017)·33 citations
13. 13*

    Stau Coannihilation, Compressed Spectrum and SUSY Discovery at the LHC

    Amin Aboubrahim🇺🇸 · Pran Nath🇺🇸 · Andrew B. Spisak🇺🇸

    The lack of observation of supersymmetry thus far implies that the weak supersymmetry scale is larger than what was thought before the LHC era. This observation is strengthened by the Higgs boson mass measurement at $\sim 125$ GeV which within supersymmetric models implies a large loop correction and a weak supersymmetry scale lying in the several TeV region. In addition if neutralino is the dark matter, its relic density puts further constraints on models often requiring coannihilation to reduce the neutralino relic density to be consistent with experimental observation. The coannihilation in turn implies that the mass gap between the LSP and the NLSP will be small leading to softer final states and making the observation of supersymmetry challenging. In this work we investigate stau coannihilation models within supergravity grand unified models and the potential of discovery of such models at the LHC in the post Higgs boson discovery era. We utilize a variety of signal regions to optimize the discovery of supersymmetry in the stau coannihilation region. In the analysis presented we impose the relic density constraint as well as the constraint of the Higgs boson mass. The range of sparticle masses discoverable up to the optimal integrated luminosity of the HL-LHC is investigated. It is found that the mass difference between the stau and the neutralino does not exceed $\sim 20$ GeV over the entire mass range of the models explored. Thus the discovery of a supersymmetric signal arising from the stau coannihilation region will also provide a measurement of the neutralino mass. The direct detection of neutralino dark matter is analyzed within the class of stau coannihilation models investigated. The analysis is extended to include multi-particle coannihilation where stau along with chargino and the second neutralino enter in the stau coannihilation process.

    hep-phhep-exPRD(2017)·27 citations
14. 14*

    Heavy flavor production in high-energy $pp$ collisions: color dipole description

    Victor P. Goncalves🇧🇷 · Boris Kopeliovich🇨🇱 · Jan Nemchik🇨🇿 · Roman Pasechnik🇸🇪 · Irina Potashnikova🇨🇱

    We present a detailed study of open heavy flavor production in high-energy $pp$ collisions at the LHC in the color dipole framework. The transverse momentum distributions of produced $b$-jets, accounting for the jet energy loss, as well as produced open charm $D$ and bottom $B$ mesons in distinct rapidity intervals relevant for LHC measurements are computed. The dipole model results for the differential $b$-jet production cross section are compared to the recent ATLAS and CMS data while the results for $D$ and $B$ mesons production cross sections -- to the corresponding LHCb data. Several models for the phenomenological dipole cross section have been employed to estimate theoretical uncertainties of the dipole model predictions. We demonstrate that the primordial transverse momentum distribution of the projectile gluon significantly affects the meson spectra at low transverse momenta and contributes to the largest uncertainty of the dipole model predictions.

    hep-phPRD(2017)·25 citations
15. 15*

    CP Asymmetries in Strange Baryon Decays

    I. I. Bigi🇺🇸 · Xian-Wei Kang🇹🇼 · Hai-Bo Li🇨🇳

    While indirect & direct CP violations (CPV) had been established in the decays of strange & beauty mesons, none have been done for baryons. There are different "roads" for finding CP asymmetries in the decays of strange baryons; they are highly non-trivial ones. The HyperCP Collaboration had probed CPV in the decays of single $\Xi$ & $\Lambda$ [Phys.Rev.Lett 93 (2004) 262001]. We talk about future lessons from $e^{+}{e}^{-}$ collisions at BESIII/BEPCII: probing decays of pairs of strange baryons, namely $\Lambda$, $\Sigma$ & $\Xi$. Realistic goals are to learn about non-perturbative QCD. One can hope to find CPV in the decays of strange baryons; one can also dream to find impact of New Dynamics (ND). We point out that a new important era starts with the BESIII/BEPCII data accumulated by the end of 2018.

    hep-phhep-exCPC(2018)·29 citations
16. 16*

    Nonstandard interactions in solar neutrino oscillations with Hyper-Kamiokande and JUNO

    Jiajun Liao🇺🇸 · Danny Marfatia🇺🇸 · Kerry Whisnant🇺🇸

    Measurements of the solar neutrino mass-squared difference from KamLAND and solar neutrino data are somewhat discrepant, perhaps due to nonstandard neutrino interactions in matter. We show that the zenith angle distribution of solar neutrinos at Hyper-Kamiokande and the energy spectrum of reactor antineutrinos at JUNO can conclusively confirm the discrepancy and detect new neutrino interactions.

    hep-phastro-ph.SRhep-exnucl-exPLB(2017)·40 citations
17. 17*

    An analytic solution to the spin flavor precession for solar Majorana neutrinos in the case of three neutrino generations

    Deniz Yilmaz🇹🇷

    The spin flavor precession (SFP) is investigated in the three neutrino generation case assuming that the neutrinos are Majorana type. Approximate analytical formulas including all transition magnetic moments are provided for the electron neutrino survival probability and electron neutrino -> electron anti-neutrino transition probability in the SFP framework. The accuracy of the formulas is checked out for two different magnetic field profiles in the Sun.

    hep-phTurk.J.Phys.(2018)·2 citations
18. 18*

    Study of parameter degeneracy and hierarchy sensitivity of NO$\nu$A in presence of sterile neutrino

    Monojit Ghosh🇯🇵 · Shivani Gupta🇦🇺 · Zachary M. Matthews🇦🇺 · Pankaj Sharma🇦🇺 · Anthony G. Williams🇦🇺

    The first hint of the neutrino mass hierarchy is believed to come from the long-baseline experiment NO$\nu$A. Recent results from the NO$\nu$A shows a mild preference towards the CP phase ${\delta }_{13}=-90^{\circ }$ and normal hierarchy. Fortunately this is the favorable area of the parameter space which does not suffer from the hierarchy-${\delta }_{13}$ degeneracy and thus NO$\nu$A can have good hierarchy sensitivity for this true combination of hierarchy and ${\delta }_{13}$. Apart from the hierarchy-${\delta }_{13}$ degeneracy there is also the octant-${\delta }_{13}$ degeneracy. But this does not affect the favorable parameter space of NO$\nu$A as this degeneracy can be resolved with a balanced neutrino and antineutrino run. However, ff we consider the existence of a light sterile neutrino then there may be additional degeneracies which can spoil the hierarchy sensitivity of NO$\nu$A even in the favorable parameter space. In the present work we find that apart from the degeneracies mentioned above, there are additional hierarchy and octant degeneracies that appear with the new phase ${\delta }_{14}$ in the presence of a light sterile neutrino in the eV scale. In contrast to the hierarchy and octant degeneracies appearing with ${\delta }_{13}$, the parameter space for hierarchy-${\delta }_{14}$ degeneracy is different in neutrinos and antineutrinos though the octant-${\delta }_{14}$ degeneracy behaves similarly in neutrinos and antineutrinos. We study the effect of these degeneracies on the hierarchy sensitivity of NO$\nu$A for the true normal hierarchy.

    hep-phPRD(2017)·23 citations
19. 19*

    In-Medium Bottomonium Production in Heavy-Ion Collisions

    Xiaojian Du🇺🇸 · Min He🇨🇳 · Ralf Rapp🇺🇸

    We study bottomonium production in heavy-ion collisions using a transport model which utilizes kinetic-rate and Boltzmann equations to calculate the energy, centrality and transverse-momentum ($p_T$) dependence of the yields. Both gluo-dissociation and inelastic parton-induced break-up including interference effects are improved over previous work by using in-medium binding energies from a thermodynamic $T$-matrix approach. A coalescence model with bottom-quark spectra from Langevin simulations is implemented to account for thermal off-equilibrium effects in the $p_T$-spectra of the regeneration contribution. We also update the equation of state for the bulk medium by extracting it from lattice-QCD results. A systematic analysis of bottomonium observables is conducted in comparison to RHIC and LHC data. In particular, the off-equilibrium bottom-quark spectra are found to play an important role in the bottomonium $p_T$ spectra.

    hep-phnucl-thNPA(2017)·10 citations
20. 20*

    The Standard Model Gauge Symmetry from Higher-Rank Unified Groups in Grand Gauge-Higgs Unification Models

    Kentaro Kojima🇯🇵 · Kazunori Takenaga🇯🇵 · Toshifumi Yamashita🇯🇵

    We study grand unified models in the five-dimensional space-time where the extra dimension is compactified on $S^1/Z_2$. The spontaneous breaking of unified gauge symmetries is achieved via vacuum expectation values of the extra-dimensional components of gauge fields. We derive one-loop effective potentials for the zero modes of the gauge fields in SU(7), SU(8), SO(10), and $E_6$ models. In each model, the rank of the residual gauge symmetry that respects the boundary condition imposed at the orbifold fixed points is higher than that of the standard model. We verify that the residual symmetry is broken to the standard model gauge symmetry at the global minima of the effective potential for certain sets of bulk fermion fields in each model.

    hep-phJHEP(2017)·30 citations
21. 21*

    Light exotic Higgs bosons at the LHC

    Shoaib Munir🇰🇷

    Most models of new physics contain extended Higgs sectors with multiple Higgs bosons. The observation of an additional Higgs boson, besides the $\sim 125$ GeV `$h_{\mathrm{obs}}$', will thus serve as an irrefutable evidence of physics beyond the Standard Model (SM). However, even when fairly light, these additional Higgs bosons may have escaped detection at the Large Electron-Positron collider, the Tevatron and the Large Hadron Collider (LHC) hitherto, owing to their highly reduced couplings to the SM particles. Therefore, in addition to the searches based on the conventional production processes of these Higgs bosons, such as gluon or vector boson fusion, possible new search modes need to be exploited at collider experiments in order to establish their signatures. We investigate here the phenomenology of pseudoscalars, with masses ranging from $\mathcal{O}$(1) GeV to about 150 GeV, in the Next-to-Minimal Supersymmetric SM and the Type-I 2-Higgs Doublet Model in some such atypical search channels at the LHC Run-II.

    hep-phJ.Phys.Conf.Ser.(2017)·0 citations
22. 22*

    A U(1) non-universal anomaly-free model with three Higgs doublets and one singlet scalar field

    S. F. Mantilla🇨🇴 · R. Martinez🇨🇴

    The flavor problem, neutrino physics and the fermion mass hierarchy are important motivations to extend the Standard Model into the TeV scale. A new family non-universal extension is presented with three Higgs doublets, one Higgs singlet and one scalar dark matter candidate. Exotic fermions are included in order to cancel chiral anomalies and to allow family non-universal ${\mathrm{U}(1)}_X$ charges. By implementing an additional ${\mathbb{Z}}_2$ symmetry the Yukawa coupling terms are suited in such a way that the fermion mass hierarchy is obtained without fine-tuning. The neutrino sector include Majorana fermions to implement inverse see-saw mechanism. The effective mass matrix for SM neutrinos is fitted to current neutrino oscillation data to check the consistency of the model with experimental evidence, obtaining that the normal-ordering scheme is preferred over the inverse ones and the values of the neutrino Yukawa coupling constants are shown. Finally, the $h\to \tau \mu$ lepton-flavor-violation process is addressed with the rotation matrices of the CP-even scalars, left- and right-handed charged leptons, yielding definite regions where the model is consistent with CMS reports of $\mathrm{BR}(h\to \tau \mu )$. Keywords: Flavor Problem, Neutrino Physics, Extended Scalar Sectors, Beyond Standard Model, Fermion masses, Inverse See-Saw Mechanism, LFV.

    hep-phPRD(2017)·10 citations
23. 23*

    Single spin asymmetries in forward p-p/A collisions revisited: the role of color entanglement

    Jian Zhou🇨🇳

    We calculate the single transverse spin asymmetries(SSA) for forward inclusive particle production in pp and pA collisions using a hybrid approach. It is shown that the Sivers type contribution to the SSA drops out due to color entanglement effect, whereas the fragmentation contribution to the spin asymmetry is not affected by color entanglement effect. This finding offers a natural solution for the sign mismatch problem.

    hep-phnucl-exPRD(2017)·9 citations
24. 24*

    Charmed Baryon ${\Lambda }_c$ in Nuclear Matter

    Keisuke Ohtani🇯🇵 · Ken-ji Araki🇯🇵 · Makoto Oka🇯🇵

    Density dependences of the mass and self-energies of ${\Lambda }_c$ in nulear matter are studied in the parity projected QCD sum rule. Effects of nuclear matter are taken into account through the quark and gluon condensates. It is found that the four-quark condensates give dominant contributions. As the density dependences of the four-quark condensates are not known well, we examine two hypotheses. One is based on the factorization hypothesis (F-type) and the other is derived from the perturbative chiral quark model (QM-type). The F-type strongly depends on density, while the QM-type gives a weaker dependence. It is found that, for the F-type dependence, the energy of ${\Lambda }_c$ increases as the density of nuclear matter grows, that is, ${\Lambda }_c$ feels repulsion. On the other hand, the QM-type predicts a weak attraction ($\sim 20$ MeV at the normal nuclear density) for ${\Lambda }_c$ in nuclear matter. We carry out a similar analysis of the $\Lambda$ hyperon and find that the F-type density dependence is too strong to explain the observed binding energy of $\Lambda$ in nuclei. Thus we conclude that the weak density dependence of the four-quark condensate is more realistic. The scalar and vector self-energies of ${\Lambda }_c$ for the QM-type dependence are found to be much smaller than those of the light baryons.

    hep-phnucl-thPRC(2017)·12 citations
25. 25*

    Physics Opportunities for Vector-Boson Scattering at a Future 100 TeV Hadron Collider

    B. Jager🇩🇪 · L. Salfelder🇩🇪 · M. Worek🇩🇪 · D. Zeppenfeld🇩🇪

    Vector-boson scattering (VBS) processes provide particularly promising means for probing the mechanism of electroweak symmetry breaking and to search for new physics in the weak sector. In the environment of a future proton-proton collider operating at a center-of-mass energy of 100 TeV, unprecedented opportunities arise for the investigation of this important class of reactions. We highlight the prominent features of VBS processes in this energy regime and discuss how the VBS signal can be isolated in the presence of a priori large QCD backgrounds. We find excellent opportunities for the analysis of VBS reactions in a kinematic range that is inaccessible to present colliders.

    hep-phhep-exPRD(2017)·14 citations
26. 26*

    Interpretation of the new ${\Omega }_c^0$ states via their mass and width

    S. S. Agaev🇦🇿 · K. Azizi🇹🇷 · H. Sundu🇹🇷

    The mass and pole residue of the ground and first radially excited ${\Omega }_c^0$ states with spin-parities $J^P=1/2^{+},3/2^{+}$, as well as P-wave ${\Omega }_c^0$ with $J^P=1/2^{-},3/2^{-}$ are calculated by means of the two-point QCD sum rules. The strong decays of ${\Omega }_c^0$ baryons are also studied and width of these decay channels are computed. The relevant computations are performed in the context of the full QCD sum rules on the light-cone. Obtained results for the masses and widths are confronted with recent experimental data of LHCb Collaboration, which allow us to interpret ${\Omega }_c(3000{)}^0$, ${\Omega }_c(3050{)}^0$, and ${\Omega }_c(3119{)}^0$ as the excited $css$ baryons with the quantum numbers $(1P,1/2^{-})$, $(1P,3/2^{-})$, and $(2S,3/2^{+})$, respectively. The $(2S,1/2^{+})$ state can be assigned either to ${\Omega }_c(3066{)}^0$ state or ${\Omega }_c(3090{)}^0$ excited baryon.

    hep-phhep-exhep-latEPJC(2017)·77 citations
27. 27*

    Non-Abelian Vector Boson Dark Matter, its Unified Route and signatures at the LHC

    Basabendu Barman🇮🇳 · Subhaditya Bhattacharya🇮🇳 · Sunando Kumar Patra (IIT Guwahati)🇮🇳 · Joydeep Chakrabortty (IIT Kanpur)🇮🇳

    Vector boson dark matter (DM) appears in $SU(2{)}_N$ extension ($N$ stands for neutral) of Standard Model (SM) where an additional global $U(1{)}_P$ symmetry is assumed and results in a generalized lepton number defined as: $L=P+T_{3N}$. Breaking of $U(1{)}_P$ leads to the breaking of $L$ to $(-1{)}^L$, thus stabilizing DM through modified $R=(-1{)}^{3B+L+2J}$. This model, already discussed in literature, offers several novel features to elaborate upon. For example, $t$-channel annihilation and dominant $s$-channel direct search, along with co-annihilation, helps the DM to evade stringent direct search bounds from LUX and XENON1T after satisfying relic density constraints. On the other hand, the exotic particles of the model can be produced at the Large Hadron Collider (LHC) yielding multilepton final states. Hadronically quiet four lepton signal with large missing energy, in specific, is shown to provide a smoking gun signature of such a framework. We study the details of $E(6)\to SM\otimes SU(2{)}_N$ breaking patterns (through D-parity odd/even cases) which yield important phenomenological consequences.

    hep-phJCAP(2017)·29 citations
28. 28*

    QCD-Electroweak First-Order Phase Transition in a Supercooled Universe

    Satoshi Iso🇯🇵 · Pasquale D. Serpico🇫🇷 · Kengo Shimada🇫🇷

    If the electroweak sector of the standard model is described by classically conformal dynamics, the early Universe evolution can be substantially altered. It is already known that---contrarily to the standard model case---a first order electroweak phase transition may occur. Here we show that, depending on the model parameters, a dramatically different scenario may happen: A first-order, six massless quark QCD phase transition occurs first, which then triggers the electroweak symmetry breaking. We derive the necessary conditions for this dynamics to occur, using the specific example of the classically conformal B-L model. In particular, relatively light weakly coupled particles are predicted, with implications for collider searches. This scenario is also potentially rich in cosmological consequences, such as renewed possibilities for electroweak baryogenesis, altered dark matter production, and gravitational wave production, as we briefly comment upon.

    hep-phastro-ph.COPRL(2017)·170 citations
29. 29*

    Right-handed neutrino dark matter in the classically conformal U(1)' extended Standard Model

    Satsuki Oda🇯🇵 · Nobuchika Okada🇺🇸 · Dai-suke Takahashi🇯🇵

    We consider the dark matter (DM) scenario in the context of the classically conformal U(1)' extended standard model (SM), with three right-handed neutrinos (RHNs) and the U(1)' Higgs field. The model is free from all the U(1)' gauge and gravitational anomalies in the presence of the three RHNs. We introduce a $Z_2$-parity in the model, under which an odd-parity is assigned to one RHN, while all the other particles is assigned to be $Z_2$-even, and hence the $Z_2$-odd RHN serves as a DM candidate. In this model, the U(1)' gauge symmetry is radiatively broken through the Coleman-Weinberg mechanism, by which the electroweak symmetry breaking is triggered. There are three free parameters in our model, the U(1)' charge of the SM Higgs doublet ($x_H$), the new U(1)' gauge coupling ($g_X$), and the U(1)' gauge boson ($Z^{\prime }$) mass ($m_{Z^{\prime }}$), which are severely constrained in order to solve the electroweak vacuum instability problem, and satisfy the LHC Run-2 bounds from the search for $Z^{\prime }$ boson resonance. In addition to these constraints, we investigate the RHN DM physics. Because of the nature of classical conformality, we find that a RHN DM pair mainly annihilates into the SM particles through the $Z^{\prime }$ boson exchange. This is the so-called $Z^{\prime }$-portal DM scenario. Combining the electroweak vacuum stability condition, the LHC Run-2 bounds, and the cosmological constraint from the observed DM relic density, we find that all constrains complementarily work to narrow down the allowed parameter regions, and, especially, exclude $m_{Z^{\prime }}\lesssim 3.5$ TeV. For the obtained allowed regions, we calculate the spin-independent cross section of the RHN DM with nucleons. We find that the resultant cross section well below the current experimental upper bounds.

    hep-phPRD(2017)·35 citations
30. 30*

    Patterns and partners for chiral symmetry restoration

    A. Gomez Nicola🇪🇸 · J. Ruiz de Elvira🇨🇭

    We present and analyze a new set of Ward Identities which shed light on the distinction between different patterns of chiral symmetry restoration in QCD, namely $O(4)$ vs $O(4)\times U(1{)}_A$. The degeneracy of chiral partners for all scalar and pseudoscalar meson nonet members are studied through their corresponding correlators. Around chiral symmetry degeneration of $O(4)$ partners, our analysis predicts that $U(1{)}_A$ partners are also degenerated. Our analysis also leads to $I=1/2$ scalar-pseudoscalar partner degeneration at exact chiral restoration, and supports ideal mixing between the $\eta$-${\eta }^{\prime }$ and the $f_0(500)$-$f_0(980)$ mesons at $O(4)\times U(1{)}_A$ restoration, with a possible range where the pseudoscalar mixing vanishes if the two transitions are well separated. We test our results with lattice data and provide further relevant observables regarding chiral and $U(1{)}_A$ restoration for future lattice and model analyses.

    hep-phhep-lathep-thnucl-thPRD(2018)·36 citations
31. 31*

    Bottomonium dissociation in a finite density plasma

    Nelson R. F. Braga🇧🇷 · Luiz F. Ferreira🇧🇷

    We present a holographic description of the thermal behavior of $b\bar{b}$ heavy vector mesons inside a plasma at finite temperature and density. The meson dissociation in the medium is represented by the decrease in the height of the spectral function peaks. In order to find a description for the evolution of the quasi-states with temperature and chemical potential it is crucial to use a model that is consistent with the decay constant behavior. The reason is that the height of a spectral function peak is related to the value of the zero temperature decay constant of the corresponding particle. AdS/QCD holographic models are in general not consistent with the observation that decay constants of heavy vector mesons decrease with radial excitation level. However, it was recently shown that using a soft wall background and calculating the correlation functions at a finite position of anti-de Sitter space, associated with an ultraviolet energy scale, it is possible to describe the observed behavior. Here we extend this proposal to the case of finite temperature $T$ and chemical potential $\mu$. A clear picture of the dissociation of bottomonium states as a function of $\mu$ and $T$ emerges from the spectral function. The energy scales where the change in chemical potential leads to changes in the thermal properties of the mesons is consistent with QCD expectations.

    hep-phhep-thPLB(2017)·34 citations
32. 32*

    Exposing the QCD Splitting Function with CMS Open Data

    Andrew Larkoski🇺🇸 · Simone Marzani🇺🇸 · Jesse Thaler🇺🇸 · Aashish Tripathee🇺🇸 · Wei Xue🇺🇸

    The splitting function is a universal property of quantum chromodynamics (QCD) which describes how energy is shared between partons. Despite its ubiquitous appearance in many QCD calculations, the splitting function cannot be measured directly since it always appears multiplied by a collinear singularity factor. Recently, however, a new jet substructure observable was introduced which asymptotes to the splitting function for sufficiently high jet energies. This provides a way to expose the splitting function through jet substructure measurements at the Large Hadron Collider. In this letter, we use public data released by the CMS experiment to study the 2-prong substructure of jets and test the 1 -> 2 splitting function of QCD. To our knowledge, this is the first ever physics analysis based on the CMS Open Data.

    hep-phhep-exPRL(2017)·76 citations
33. 33*

    Probing new light force-mediators by isotope shift spectroscopy

    Julian C. Berengut🇦🇺 · Dmitry Budker🇩🇪 · Cedric Delaunay🇫🇷 · Victor V. Flambaum🇦🇺 · Claudia Frugiuele🇮🇱 · Elina Fuchs🇮🇱 · Christophe Grojean🇩🇪 · Roni Harnik🇺🇸 · Roee Ozeri🇮🇱 · Gilad Perez🇮🇱 · Yotam Soreq🇺🇸

    In this Letter we explore the potential of probing new light force-carriers, with spin-independent couplings to the electron and the neutron, using precision isotope shift spectroscopy. We develop a formalism to interpret linear King plots as bounds on new physics with minimal theory inputs. We focus only on bounding the new physics contributions that can be calculated independently of the Standard Model nuclear effects. We apply our method to existing Ca+ data and project its sensitivity to possibly existing new bosons using narrow transitions in other atoms and ions (specifically, Sr and Yb). Future measurements are expected to improve the relative precision by five orders of magnitude, and can potentially lead to an unprecedented sensitivity for bosons within the 10 keV to 10 MeV mass range.

    hep-phphysics.atm-clusquant-phPRL(2018)·175 citations
34. 34*

    Revealing the collision energy dependence of $\eta /s$ in RHIC-BES Au+Au collisions using Bayesian statistics

    Jussi Auvinen🇺🇸 · Iurii Karpenko🇮🇹 · Jonah E. Bernhard🇺🇸 · Steffen A. Bass🇺🇸

    We investigate the collision energy dependence of $\eta /s$ in a transport + viscous hydrodynamics hybrid model. A Bayesian analysis is performed on RHIC beam energy scan data for $Au+Au$ collisions at $\sqrt{s_{NN}}=19.6,39,$ and $62.4$ GeV. The resulting posterior probability distributions for the model parameters show a preference for a larger value of $\eta /s$ at $19.6$ GeV compared to $62.4$ GeV, indicating dependence on baryon chemical potential ${\mu }_B$.

    ↳ nucl-thhep-phNPA(2017)·10 citations
35. 35*

    Event-by-event $v_n$ correlations of soft hadrons and heavy mesons in heavy ion collisions

    Caio A. G. Prado🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸 · Roland Katz🇧🇷 · Jorge Noronha🇧🇷 · Marcelo G. Munhoz🇧🇷 · Alexandre A. P. Suaide🇧🇷

    Combining event-by-event hydrodynamics with heavy quark energy loss we compute correlations between the heavy and soft sectors for elliptic and triangular flow harmonics $v_2$ and $v_3$ of D${}^0$ mesons in PbPb collisions at $2.76$ TeV and $5.02$ TeV. Our results indicate that $v_3$ is strongly influenced by the fragmentation temperature and that it builds up later than $v_2$ during the evolution of the system.

    ↳ nucl-thhep-phnucl-exNPA(2017)·2 citations
36. 36*

    Charged black holes in a generalized scalar-tensor gravity model

    Yves Brihaye (Uni Mons, Belgium)🇧🇪 · Betti Hartmann (IFSC/USP, Brazil)🇧🇷

    We study 4-dimensional charged and static black holes in a generalized scalar-tensor gravity model, in which a shift symmetry for the scalar field exists. For vanishing scalar field the solution corresponds to the Reissner-Nordström (RN) solution, while solutions of the full scalar-gravity model have to be constructed numerically. We demonstrate that these black holes support galilean scalar hair up to a maximal value of the scalar-tensor coupling that depends on the value of the charge and can be up to roughly twice as large as that for uncharged solutions. The Hawking temperature $T_{\mathrm{H}}$ of the hairy black holes at maximal scalar-tensor coupling decreases continuously with the increase of the charge and reaches $T_{\mathrm{H}}=0$ for the highest possible charge that these solutions can carry. However, in this limit, the scalar-tensor coupling needs to vanish. The limiting solution hence corresponds to the extremal RN solution, which does not support regular galilaen scalar hair due to its AdS${}_2\times S^2$ near-horizon geometry.

    ↳ gr-qchep-phhep-thPLB(2017)·2 citations
37. 37*

    Bulk viscous effects on flow and dilepton radiation in a hybrid approach

    Gojko Vujanovic🇺🇸 · Jean-François Paquet🇺🇸 · Sangwook Ryu🇩🇪 · Chun Shen🇺🇸 · Gabriel S. Denicol🇧🇷 · Sangyong Jeon🇨🇦 · Charles Gale🇨🇦 · Ulrich Heinz🇺🇸

    Starting from IP-Glasma initial conditions, we investigate the effects of bulk pressure on low mass dilepton production at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC) energies. Though thermal dilepton $v_2$ is affected by the presence of both bulk and shear viscosity, whether or not these effects can be measured depends on the dilepton "cocktail" contribution to the the low mass dilepton $v_2$. Combining the thermal and "cocktail" dileptons, the effects of bulk viscosity on total dilepton $v_2$ is investigated.

    ↳ nucl-thhep-phnucl-exNPA(2017)·6 citations
38. 38*

    Ultra-peripheral collisions and hadronic structure

    Spencer R. Klein🇺🇸

    Ultra-peripheral collisions are the energy frontier for photon-mediated interactions, reaching, at the Large Hadron Collider (LHC), $\gamma -p$ center of mass energies five to ten times higher than at HERA and reaching $\gamma \gamma$ energies higher than at LEP. Photoproduction of heavy quarkonium and dijets in $pp$ and $pA$ collisions probes the gluon distribution in protons at Bjorken-$x$ values down to $3\times 10^{-6}$, far smaller than can be otherwise studied. In $AA$ collisions, these reactions probe the gluon distributions in heavy ions, down to $x$ values of a few $10^{-5}$. Although more theoretical work is needed to nail down all of the uncertainties, inclusion of these data in current parton distribution function fits would greatly improve the accuracy of the gluon distributions at low Bjorken-$x$ and low/moderate $Q^2$. High-statistics ${\rho }^0$ data probe the spatial distribution of the interaction sites; the site distribution is given by the Fourier transform of $d\sigma /dt$. After introducing UPCs, this review presents recent measurements of dilepton production and light-by-light scattering and recent data on proton and heavy nuclei structure, emphasizing results presented at Quark Matter 2017 (QM2017).

    ↳ nucl-exhep-exhep-phNPA(2017)·29 citations
39. 39*

    Nonlinear QED effects in X-ray emission of pulsars

    Soroush Shakeri🇮🇷 · Mansour Haghighat🇮🇷 · She-Sheng Xue🇮🇹

    In the presence of strong magnetic fields near pulsars, the QED vacuum becomes a birefringent medium due to nonlinear QED interactions. Here, we explore the impact of the effective photon-photon interaction on the polarization evolution of photons propagating through the magnetized QED vacuum of a pulsar. We solve the quantum Boltzmann equation within the framework of the Euler-Heisenberg Lagrangian to find the evolution of the Stokes parameters. We find that linearly polarized X-ray photons propagating outward in the magnetosphere of a rotating neutron star can acquire high values for the circular polarization parameter. Meanwhile, it is shown that the polarization characteristics of photons besides photon energy depend strongly on parameters of the pulsars such as magnetic field strength, inclination angle and rotational period. Our results are clear predictions of QED vacuum polarization effects in the near vicinity of magnetic stars which can be tested with the upcoming X-ray polarimetric observations.

    ↳ astro-ph.HEhep-phJCAP(2017)·14 citations
40. 40*

    Four dimensional ambitwistor strings and form factors of local and Wilson line operators

    L.V.Bork🇷🇺 · A.I.Onishchenko🇷🇺

    We consider the description of form factors of local and Wilson line operators (reggeon amplitudes) in N=4 SYM within the framework of four dimensional ambitwistor string theory. We present the explicit expressions for string composite operators corresponding to stress-tensor operator supermultiplet and Wilson line operator insertion. It is shown, that corresponding tree-level string correlation functions correctly reproduce previously obtained Grassmannian integral representations. As by product we derive four dimensional tree-level scattering equations representations for the mentioned form factors and formulate a simple gluing procedure used to relate operator form factors with on-shell amplitudes.

    ↳ hep-thhep-phPRD(2018)·16 citations
41. 41*

    Constraints on inflation revisited: An analysis including the latest local measurement of the Hubble constant

    Rui-Yun Guo🇨🇳 · Xin Zhang🇨🇳

    We revisit the constraints on inflation models by using the current cosmological observations involving the latest local measurement of the Hubble constant ($H_0=73.00\pm 1.75$ km s ${}^{-1}$ Mpc${}^{-1}$). We constrain the primordial power spectra of both scalar and tensor perturbations with the observational data including the Planck 2015 CMB full data, the BICEP2 and Keck Array CMB B-mode data, the BAO data, and the direct measurement of $H_0$. In order to relieve the tension between the local determination of the Hubble constant and the other astrophysical observations, we consider the additional parameter $N_{\mathrm{eff}}$ in the cosmological model. We find that, for the $\Lambda$CDM+$r$+$N_{\mathrm{eff}}$ model, the scale invariance is only excluded at the 3.3$\sigma$ level, and $\Delta N_{\mathrm{eff}}>0$ is favored at the 1.6$\sigma$ level. Comparing the obtained 1$\sigma$ and 2$\sigma$ contours of $(n_s,r)$ with the theoretical predictions of selected inflation models, we find that both the convex and concave potentials are favored at 2$\sigma$ level, the natural inflation model is excluded at more than 2$\sigma$ level, the Starobinsky $R^2$ inflation model is only favored at around 2$\sigma$ level, and the spontaneously broken SUSY inflation model is now the most favored model.

    ↳ astro-ph.COgr-qchep-phhep-thEPJC(2017)·30 citations
42. 42*

    Superradiant Instability and Backreaction of Massive Vector Fields around Kerr Black Holes

    William E. East🇨🇦 · Frans Pretorius🇺🇸

    We study the growth and saturation of the superradiant instability of a complex, massive vector (Proca) field as it extracts energy and angular momentum from a spinning black hole, using numerical solutions of the full Einstein-Proca equations. We concentrate on a rapidly spinning black hole ($a=0.99$) and the dominant $m=1$ azimuthal mode of the Proca field, with real and imaginary components of the field chosen to yield an axisymmetric stress-energy tensor and, hence, spacetime. We find that in excess of $9\%$ of the black hole's mass can be transferred into the field. In all cases studied, the superradiant instability smoothly saturates when the black hole's horizon frequency decreases to match the frequency of the Proca cloud that spontaneously forms around the black hole.

    ↳ gr-qcastro-ph.HEhep-phPRL(2017)·360 citations
43. 43*

    Thermal Schwinger pair production at arbitrary coupling

    Oliver Gould🇬🇧 · Arttu Rajantie🇬🇧

    We calculate the rate of thermal Schwinger pair production at arbitrary coupling in weak external fields. Our calculations are valid independently of many properties of the charged particles produced, in particular their spin and whether they are electric or magnetic. Using the worldline formalism, we calculate the logarithm of the rate to leading order in the weak external field and to all orders in virtual photon exchange, taking us beyond the perturbative expansion about the leading order, weak coupling result.

    ↳ hep-thhep-phPRD(2017)·83 citations
44. 44*

    Jet Measurements with Neutral and Di-jet Triggers in Central Au+Au Collisions at $\sqrt{s_{NN}}$ = 200 GeV with STAR

    Nihar Ranjan Sahoo (for the STAR Collaboration)🇺🇸

    We present two measurements related to jet production in p+p and central Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. Firstly, a study of semi-inclusive charged recoil jets coincident with high-${\mathrm{p}}_{\mathrm{T}}$ direct-photon and neutral pions, and secondly, the hadron correlations with respect to reconstructed di-jet triggers. Indication of medium effects is observed by comparing $\gamma$+jet and ${\pi }^0$+jet measurements. The di-jet+hadron study shows signs that the medium-induced modifications of an imbalanced set of di-jets with "hard cores" primarily affect the recoil jet.

    ↳ nucl-exhep-exhep-phnucl-thNPA(2017)·1 citation
45. 45*

    Maximal Supersymmetry and B-Mode Targets

    Renata Kallosh🇺🇸 · Andrei Linde🇺🇸 · Timm Wrase🇦🇹 · Yusuke Yamada🇺🇸

    Extending the work of Ferrara and one of the authors, we present dynamical cosmological models of $\alpha$-attractors with plateau potentials for $3\alpha =1,2,3,4,5,6,7$. These models are motivated by geometric properties of maximally supersymmetric theories: M-theory, superstring theory, and maximal $N=8$ supergravity. After a consistent truncation of maximal to minimal supersymmetry in a seven-disk geometry, we perform a two-step procedure: 1) we introduce a superpotential, which stabilizes the moduli of the seven-disk geometry in a supersymmetric minimum, 2) we add a cosmological sector with a nilpotent stabilizer, which breaks supersymmetry spontaneously and leads to a desirable class of cosmological attractor models. These models with $n_s$ consistent with observational data, and with tensor-to-scalar ratio $r\approx 10^{-2}-10^{-3}$, provide natural targets for future B-mode searches. We relate the issue of stability of inflationary trajectories in these models to tessellations of a hyperbolic geometry.

    ↳ hep-thastro-ph.COgr-qchep-phJHEP(2017)·69 citations
46. 46*

    Supersymmetry preserving and breaking degenerate vacua, and radiative moduli stabilization

    Tatsuo Kobayashi🇯🇵 · Naoya Omoto🇯🇵 · Hajime Otsuka🇯🇵 · Takuya H. Tatsuishi🇯🇵

    We propose a new type of moduli stabilization scenario where the supersymmetric and supersymmetry-breaking minima are degenerate at the leading level. The inclusion of the loop-corrections originating from the matter fields resolves this degeneracy of vacua. Light axions are predicted in one of our models.

    ↳ hep-thhep-phPRD(2017)·4 citations
47. 47*

    Topology in the SU(N_f) chiral symmetry restored phase of unquenched QCD and axion cosmology II

    Vicente Azcoiti🇪🇸

    We investigate the physical consequences of the survival of the effects of the U(1)_A anomaly in the chiral symmetric phase of QCD, and show that the free energy density is a singular function of the quark mass m, in the chiral limit, and that the $\sigma$ and $\bar{\pi }$ susceptibilities diverge in this limit at any $T\ge T_c$. We also show that the difference between the $\bar{\pi }$ and $\bar{\delta }$ susceptibilities diverges in the chiral limit at any $T\ge T_c$, a result which seems to be excluded by recent results of Tomiya et al. from numerical simulations of two-flavor QCD. We also discuss on the generalization of these results to the $N_f\ge 3$ model.

    ↳ hep-lathep-phhep-thnucl-thPRD(2017)·11 citations
48. 48*

    Properties and uses of factorial cumulants in relativistic heavy-ion collisions

    Masakiyo Kitazawa🇯🇵 · Xiaofeng Luo🇨🇳

    We discuss properties and applications of factorial cumulants of various particle numbers and for their mixed channels measured by the event-by-event analysis in relativistic heavy-ion collisions. After defining the factorial cumulants for systems with multi-particle species, their properties are elucidated. The uses of the factorial cumulants in the study of critical fluctuations are discussed. We point out that factorial cumulants play useful roles in understanding fluctuation observables when they have underlying physics approximately described by the binomial distribution. As examples, we suggest novel utilization methods of the factorial cumulants in the study of the momentum cut and rapidity window dependences of fluctuation observables.

    ↳ nucl-thhep-phnucl-exPRC(2017)·50 citations
49. 49*

    Sign Flip in the Casimir Force for Interacting Fermion Systems

    Antonino Flachi🇯🇵 · Muneto Nitta🇯🇵 · Satoshi Takada🇯🇵 · Ryosuke Yoshii🇯🇵

    In this work we consider a fermionic chain of finite length $\ell$. Fermions are allowed to interact and are forced to obey boundary conditions, thus altering the process of condensation. Our goal is to explore how this affects the quantum vacuum energy for this system. We approach this problem by using a self-consistent method and observe a nontrivial behavior in the Casimir force, displaying a switch from an attractive to a repulsive regime. This flip stems from the competition between the attractive contribution from the usual fermionic Casimir effect and a repulsive one coming from the condensate.

    ↳ hep-thcond-mat.supr-conhep-phquant-phPRL(2017)·38 citations
50. 50*

    The onset of fluid-dynamical behavior in relativistic kinetic theory

    Jorge Noronha (Sao Paulo U.)🇧🇷 · Gabriel S. Denicol (Niteroi, Fluminense U.)🇧🇷

    In this proceedings we discuss recent findings regarding the large order behavior of the Chapman-Enskog expansion in relativistic kinetic theory. It is shown that this series in powers of the Knudsen number has zero radius of convergence in the case of a Bjorken expanding fluid described by the Boltzmann equation in the relaxation time approximation. This divergence stems from the presence of non-hydrodynamic modes, which give non-perturbative contributions to the Knudsen series.

    ↳ nucl-thhep-phNPA(2017)·2 citations
51. 51*

    Mixed Harmonic Correlations: Hydrodynamics Predictions at RHIC using Experimental Analysis Techniques

    Fernando G. Gardim🇧🇷 · Frederique Grassi🇧🇷 · Matthew Luzum🇧🇷 · Jacquelyn Noronha-Hostler🇺🇸

    Correlations of different azimuthal flow harmonics $v_n$ and symmetry planes ${\Psi }_n$ can add constraints to theoretical models, and probe aspects of the system that are independent of the traditional single-harmonic measurements. Using NeXSPheRIO, a hydrodynamical model which has accurately reproduced a large set of single-harmonic correlations at RHIC, we make predictions of these new observables for 200 A GeV Au+Au Collisions, providing an important baseline for comparison to correlations of flow harmonics, which contain non-trivial information about the initial state. We also point out how to properly compare theoretical calculations to measurements using wide centrality bins and non-trivial event weighting.

    ↳ nucl-thhep-phnucl-exNPA(2017)·0 citations
52. 52*

    One-particle reducible contribution to the one-loop spinor propagator in a constant field

    Naser Ahmadiniaz🇰🇷 · Fiorenzo Bastianelli🇮🇹 · Olindo Corradini🇮🇹 · James P. Edwards🇲🇽 · Christian Schubert🇲🇽

    Extending work by Gies and Karbstein on the Euler-Heisenberg Lagrangian, it has recently been shown that the one-loop propagator of a charged scalar particle in a constant electromagnetic field has a one-particle reducible contribution in addition to the well-studied irreducible one. Here we further generalize this result to the spinor case, and find the same relation between the reducible term, the tree-level propagator and the one-loop Euler-Heisenberg Lagrangian as in the scalar case. Our demonstration uses a novel worldline path integral representation of the photon-dressed spinor propagator in a constant electromagnetic field background.

    ↳ hep-thastro-ph.HEhep-phNPB(2017)·42 citations
53. 53*

    Special Relativity from Soft Gravitons

    Mark P. Hertzberg🇺🇸 · McCullen Sandora🇺🇸

    We study all translationally and rotationally invariant local theories involving massless spin 2 and spin 1 particles that mediate long range forces, allowing for general energy relations and violation of boost invariance. Although gauge invariance is not a priori required to describe non Lorentz invariant theories, we first establish that locality requires `soft gauge invariance'. Then by taking the soft graviton limit in scattering amplitudes, we prove that in addition to the usual requirement of universal graviton couplings, the special relativistic energy-momentum relation is also required and must be exact. We contrast this to the case of theories with only spin $\le 1$ particles, where, although we can still derive charge conservation from locality, special relativity can be easily violated. We provide indications that the entire structure of relativity can be built up from spin 2 in this fashion.

    ↳ hep-thastro-ph.COgr-qchep-phPRD(2017)·11 citations
54. 54*

    A "nu" look at gravitational waves: The black hole birth rate from neutrinos combined with the merger rate from LIGO

    Jonathan H. Davis🇬🇧 · Malcolm Fairbairn🇬🇧

    We make projections for measuring the black hole birth rate from the diffuse supernova neutrino background (DSNB) by future neutrino experiments, and constrain the black hole merger fraction $ϵ$, when combined with information on the black hole merger rate from gravitational wave experiments such as LIGO. The DSNB originates from neutrinos emitted by all the supernovae in the Universe, and is expected to be made up of two components: neutrinos from neutron-star-forming supernovae, and a sub-dominant component at higher energies from black-hole-forming "unnovae". We perform a Markov Chain Monte Carlo analysis of simulated data of the DSNB in an experiment similar to Hyper-Kamiokande, focusing on this second component. Since all knowledge of the neutrino emission from unnovae comes from simulations of collapsing stars, we choose two sets of priors: one where the unnovae are well-understood and one where their neutrino emission is poorly known. By combining the black hole birth rate from the DSNB with projected measurements of the black hole merger rate from LIGO, we show that the fraction of black holes which lead to binary mergers observed today $ϵ$ could be constrained to be within the range $2\cdot 10^{-4}\le ϵ\le 3\cdot 10^{-2}$ at $3\sigma$ confidence, after ten years of running an experiment like Hyper-Kamiokande.

    ↳ astro-ph.HEhep-phJCAP(2017)·3 citations
55. 55*

    Chiral Vortical and Magnetic Effects in Anomalous Hydrodynamics

    Xingyu Guo🇨🇳 · Dmitri E. Kharzeev🇺🇸 · Xu-Guang Huang🇨🇳 · Wei-Tian Deng🇨🇳 · Yuji Hirono🇺🇸

    We employ a 3+1D anomalous hydrodynamics with initial condition generated by HIJING to simulate the chiral vortical effect and the chiral magnetic effect in heavy-ion collisions. This allows us to calculate the charge-dependent two-particle correlations with respect to the reaction plane at different collision energies and centralities. We then compare the computed results with the experimental data and give discussions on the possible background effects.

    ↳ nucl-thhep-phnucl-exNPA(2017)·11 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.