We report the measurements of K^*0 meson at midrapidity (|y|< 1.0) in Au+Au collisions at  √s_NN = 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV from the STAR experiment at the RHIC beam energy scan (BES) program. The transverse momentum (p_T) spectra, yield (dN/dy) and average transverse momentum (<p_T>) of K^*0  are presented as functions of collision centrality and beam energy. The K^*0/K yield ratio are presented for different collision centralities and beam energies. The K^*0/K ratio in heavy ion collisions are observed to be smaller than the same in e+e and p+p collisions. The K^*0/K ratio follow similar centrality dependent trend observed by previous RHIC and LHC measurements. The data favor the scenario of dominance of hadronic re-scattering over regeneration in between kinetic and chemical freeze-out at BES energies.

Summary:

Proposed Figures::

Fig 1: Κπ invariant mass distribution for central  and peripheral in Au+Au collisions at √s_NN  = 19.6 and 39 GeV. The solid line indicate the Breit Wigner fit and the dashed line represent the residual background.

Fig 2:  K^*0 reconstruction efficiency x acceptance as functions p_T in Au+Au collisions for different centralities for  √s_NN = 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV. 

Fig 3: K^*0  p_T spectra at midrapidity (|y|<1.0) in Au+Au collisions at  √s_NN = 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV for different centralities. The solid line indicate the Tsallis fit and the dashed line represent the extrapolation to low p_T.

Fig 4: The midrapidity yields (dN/dy) of K^*0  as functions of number of participating nucleons (<N_part>) in Au+Au collisions at  √s_NN = 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV.

Fig 5: The midrapidity mean p_T (< p_T >) of K^*0  as function of number of participating nucleons (<N_part>) in Au+Au collisions at   √s_NN= 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV.

Fig: 6: The midrapidity mean p_T (< p_T >) of π, Κ, p and K^*0  as function of number of participating nucleons (<N_part>) in Au+Au collisions at  √s_NN = 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV.

Fig 7: The K*⁰/K  ratio as function of (dN_ch/dη)^1/3 in Au+Au collisions at  √sNN = 7.7, 11.5, 14.5, 19.6, 27 and 39 GeV. The results are compared to previous measurements from STAR and ALICE.

Fig 8: The K*⁰/K  ratio as functions of beam energy in e+e, p+p, d+A, p+A and central A+A collisions. The dashed line indicate the fit to e+e and p+p data. 

Figure pdf files:
https://drupal.star.bnl.gov/STAR/blog/aswini96/K0besIpaperdraftplots

PWGC preview presentation :: KStar_spectra_8Oct_2021.pdf

Notes from PWGC: https://drupal.star.bnl.gov/STAR/event/2021/10/08/star-pwgc-meeting#comment-2070

Response to PWGC comments: KStar_spectra_PWGC_suggestions_25Oct2021.pdf

Analysis Note:
STAR Note:  psn0784
version-0 [kstar_note_pwg_review_ver0.pdf]

Paper Draft:
version-4:[kstar_draft_CollabReview_ver1.pdf] [Released for collaboration review]
version-3 [kstar_draft_GPC_ver3.pdf] 
version-2 [kstar_draft_GPC_ver2.pdf]
version-1 [kstar_draft_GPC_ver1.pdf]
version-0 [kstar_draft_pwg_review_ver0.pdf]

Analysis Code: [/gpfs01/star/pwg/aswini96/Code_QA_Kstar_BES_1/]
CVS: https://www.star.bnl.gov/cgi-bin/protected/viewvc.cgi/cvsroot/offline/paper/psn0784/

GPC Discussions:

1. Round-1-Comments and responses:
2. GPC meeting minutes: https://drupal.star.bnl.gov/STAR/blog/zbtang/minutes-GPC331-BES-K-1st-zoom-meeting 
3. Cross-checks:
    m2 fitting at the highest pT bin: https://drupal.star.bnl.gov/STAR/system/files/kaon_last_pt.pdf
    ZDCx dependence of tof-match efficiency: 
    https://drupal.star.bnl.gov/STAR/system/files/19gev_pion_tofmatch_pion.pdf
    https://drupal.star.bnl.gov/STAR/system/files/19gev_pion_tofmatch_kaon.pdf

4. Round-2- Comments from Richard Witt: kstar_draft_GPC_ver1_RWitt_Comments.pdf
    Comments and responses (Google doc)
    Response to GPC:
    Reply: https://drupal.star.bnl.gov/STAR/system/files/Response_to_GPC_Comments_round2.pdf
    Paper draft: https://drupal.star.bnl.gov/STAR/system/files/kstar_draft_GPC_ver2.pdf
    AN: https://drupal.star.bnl.gov/STAR/system/files/Analysis_Note_Kstar_ver2.pdf

Supporting documents::

QM 2017:

https://www.star.bnl.gov/protected/bulkcorr/subhash/rsn/ppts/Kstar_BES_2017_LFS.pdf
https://www.star.bnl.gov/protected/bulkcorr/subhash/rsn/ppts/Kstar_BES_2017_BulkCorr.pdf
https://www.star.bnl.gov/protected/bulkcorr/subhash/rsn/qm2017/QM17_poster_Subhash_ver8.pdf

Resonance workshop Bergamo:
https://drupal.star.bnl.gov/STAR/system/files/resonance_bergamo_ver6.pdf

SQM 2019:
https://drupal.star.bnl.gov/STAR/system/files/sqm2019_ver5.pdf
https://drupal.star.bnl.gov/STAR/system/files/draft_7.pdf

LFSUPC:
STARCollaborationMeeting_Aswini.pdf
https://drupal.star.bnl.gov/STAR/system/files/KStar_spectra_Aug20_2021_0.pdf
https://drupal.star.bnl.gov/STAR/system/files/slide2_0.pdf
https://drupal.star.bnl.gov/STAR/system/files/slide1.pdf
https://drupal.star.bnl.gov/STAR/system/files/slide_0.pdf